当前位置：搜档网 › Characterization and remediation of soils contaminated with uranium

Characterization and remediation of soils contaminated with uranium

Journal of Hazardous Materials 163(2009)475–510

Contents lists available at ScienceDirect

Journal of Hazardous

Materials

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j h a z m a

Review

Characterization and remediation of soils contaminated with uranium

Maria Gavrilescu ?,Lucian Vasile Pavel,Igor Cretescu

Technical University Iasi,Faculty of Chemical Engineering and Environmental Protection,Department of Environmental Engineering and Management,71Mangeron Boulevard,700050Iasi,Romania

a r t i c l e i n f o Article history:

Received 1December 2007

Received in revised form 23July 2008Accepted 23July 2008

Available online 31July 2008Keywords:

Bioremediation Biosorption Bioreduction

Chemical extraction Electrokinetics Environment Polluted soil Remediation Uranium

a b s t r a c t

Environmental contamination caused by radionuclides,in particular by uranium and its decay products is a serious problem worldwide.The development of nuclear science and technology has led to increasing nuclear waste containing uranium being released and disposed in the environment.

The objective of this paper is to develop a better understanding of the techniques for the remediation of soils polluted with radionuclides (uranium in particular),considering:the chemical forms of uranium,including depleted uranium (DU)in soil and other environmental media,their characteristics and con-centrations,and some of the effects on environmental and human health;research issues concerning the remediation process,the bene?ts and results;a better understanding of the range of uses and situations for which each is most appropriate.

The paper addresses the main features of the following techniques for uranium remediation:natural attenuation,physical methods,chemical processes (chemical extraction methods from contaminated soils assisted by various suitable chelators (sodium bicarbonate,citric acid,two-stage acid leaching procedure),extraction using supercritical ?uids such as solvents,permeable reactive barriers),biological processes (biomineralization and microbial reduction,phytoremediation,biosorption),and electrokinetic meth-ods.In addition,factors affecting uranium removal from soils are furthermore reviewed including soil characteristics,pH and reagent concentration,retention time.

Contents 1.Radionuclides in soil (476)

Characteristics and concentrations of uranium in the environment...............................................................................4772.1.Uranium properties..........................................................................................................................4772.2.Depleted uranium ...........................................................................................................................4792.3.Chemical forms of uranium .................................................................................................................

4792.3.1.Uranium oxides ....................................................................................................................4822.3.2.Uranium hexa?uoride.............................................................................................................4822.3.3.Uranium tetra?uoride.............................................................................................................4822.3.4.Uranium metal.....................................................................................................................

4822.4.Uranium compounds toxicity ...............................................................................................................4823.

Methods and techniques for uranium removal.....................................................................................................4833.1.General description..........................................................................................................................4833.2.Natural attenuation .........................................................................................................................4903.3.Physical processes...........................................................................................................................4913.4.Chemical methods...........................................................................................................................

4913.4.1.Chemical extraction................................................................................................................4913.4.2.Permeable reactive barriers (PRBs)................................................................................................

4963.5.Biological methods..........................................................................................................................

4973.5.1.Background.........................................................................................................................4973.5.2.Biomineralization,formation of insoluble metal sulphides and phosphates.....................................................

498

?Corresponding author.Tel.:+40232278680x2137;fax:+40232271311.E-mail addresses:mgav@ch.tuiasi.ro ,mgav ro@https://www.sodocs.net/doc/299645309.html, (M.Gavrilescu).0304-3894/$–see front matter ?2008Elsevier B.V.All rights reserved.doi:10.1016/j.jhazmat.2008.07.103

476M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510

3.5.3.Phytoremediation (499)

3.5.4.Biosorption (500)

3.6.Electrokinetic methods (501)

4.Conclusions (503)

Acknowledgments (504)

References (504)

1.Radionuclides in soil

Radionuclides are found in the soil as a consequence of some pathways[1]:

?as a part of Earth’s layer(primordial radionuclides);?generated and deposited by cosmic ray interactions;

?as a result of anthropogenic activities.

Arti?cial radionuclides are also introduced into the environ-ment following nuclear power plant accidents or nuclear weapons tests,nuclear energy activities,scienti?c and other uses[2–5].In addition,soil may interact with low-level radioactive waste mate-rials that have been buried for disposal[6–9].Radionuclides can travel around the world on air streams.Their weight and weather determine their deposition to the ground.Also,the heavy rains can bring the radioactive particles to the ground[10].Soils pos-sess sorbent and complexing capacities which contribute to the immobilization of radionuclides from water in the underlying layers,after they were displaced from complexes or adsorption sites.

Radionuclides existing in soil can be dissolved in solution,or ion exchanged in reaction,complexed with soil organics or precipitate as pure or mixed solids.They can move into the water,air and the food supply.

The immobility of these radioactive elements in uppermost soil layers represents a problem for environment and human health, since they can be easily integrated in the food chain[2,11,12].A scheme for radionuclides movement in soil was proposed by Igwe et al.[7](Fig.1).Consequently,the major part of radionuclides released into the environment will?nally accumulate in either the upper layer of soils or interstitial system of sediments in aquatic systems.As a consequence,a risk for ecosystems,agro-systems and health could be induced.

In particular,uranium mining and milling have caused enor-mous damage to the environment by means of abandoned waste accumulation and improper disposal of the radioactive material, waste dump after uranium prospections,other workings,espe-cially in the last60years since the end of the Second World War. Large amounts of uranium-containing(both high-and low-level) waste are generated from activities such as fuel fabrication,fuel reprocessing,research and development(R&D).All these negative impacts in?uenced the quality of the environment and affected mainly surface and ground waters,soils and simultaneously pol-luted great areas of land and endangered the catchments of drinking water.Also,uranium generates an important issue against public perception on the risk that the environmental contamina-tion poses to the environmental and human health[14].Therefore, it is strongly evident that the contamination caused by uranium has severe negative biological effects on important groups of the soil food web[3].

The potential risk of uranium soil contamination is a global prob-lem as about every country can be affected by one or more activities mentioned above.Depleted,enriched and natural uranium con-tamination in soil and water has been identi?ed at many sites worldwide,so that measures for preventing their assimilation by plants should be considered a preliminary step towards the reme-diation of contaminated areas[2,13–17].For a long period of time uranium was leached commercially in a large number of deposits using different in situ technologies[18–20],either alkaline leaching using solutions containing carbonate and hydrocarbonate ions,or acid leaching[21,22].

The solubility of uranium in soil is dependent on several factors such as:pH,redox potential,temperature,soil texture,organic and inorganic compounds,moisture and microbial activity[23].Soluble forms can migrate with soil water,be uptaken by plants or aquatic organisms or volatilized[7].

Several years ago,all commercial-scale operations for uranium leaching were stopped due to a complex of different political,eco-nomical and environmental reasons[24].However,regardless of some preventive and remedial actions during the uranium recovery, many natural ecosystems were heavily polluted with radioactive elements,mainly through the seepage of acid drainage waters [25–27].Such waters are still a persistent environmental problem at many abandoned mine sites,while soils around the water?ow path are polluted with radioactive elements becoming unsuitable for agricultural use,so that soil remediation has to be considered [11,28].

Another problem is the contamination of soil and water with depleted uranium,which has increased public health concerns due to the chemical toxicity of DU at elevated dosages[29–33].For this reason,there is great interest in developing methods for U removal from contaminated

sources.

Fig.1.Radionuclide transformation processes in soil(k i—reaction rate)[7].

M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510477

Various methods for remediation of soils contaminated with radioactive elements are known but only few of them have been applied under?eld conditions.The excavation and transportation of the heavily polluted soils to speci?c depositories is still a common practice in most countries[34].

The aim of this article is to provide an overview on the main aspects concerning the presence of uranium in the environment, in particular in soil,as well as on techniques for remediation of polluted soil together with recent advances in the application of these processes to the detoxi?cation of uranium contamination. 2.Characteristics and concentrations of uranium in the environment

2.1.Uranium properties

Uranium can be characterized as a heavy,ductile and slightly paramagnetic metal,silver-white in color and pyrophoric when ?nely divided and in this form it can react with cold water [23,35,36].It is the?rst element,with the atomic number92, which was found by Henry Becquerel(in1896)to possess the prop-erty to be radioactive[37].As a naturally occurring element,it contributes to low levels of natural background radiation in the environment.Uranium is found in all rock types in varying,but usually small concentrations[12,38].Uranium is widely dispersed in the earth’s crust,rocks and soils at a level of about2–4ppm by weight[12,37,39].The natural concentration of uranium in the earth crust is about10?6g/g.Also,the uranium concentration in ocean water,plants,and animal organisms is around10?7g/g,as a result of the solubility of U(VI)compounds in water[40].

Volcanic eruption is another natural phenomenon that may increase the concentration of natural uranium in the soil.The redis-tribution of uranium and uranium progeny to both soil and water occurs often naturally in environmental circuit.

Uranium is in fact more abundant than gold,silver,mercury, antimony or cadmium,and more or less as common as tin,cobalt, lead,molybdenum and arsenic[4,41].It is an extremely dense metal (at19g/cm3,about twice as heavy per unit volume as lead),being the heaviest chemical element to be found in the nature.Natural uranium exists in three different forms(isotopes),all of which are radioactive[41,42].The two most abundant isotopes,uranium235 (0.72%)and uranium-238(99.27%),have radioactive half-lives of about7×108and4.4×109years,respectively[12,43].An impor-tant characteristic is its toxicity[4,37].

Uranium is found in virtually all rock and soil(being derived from erosion of the rocks),it is essentially everywhere in ground-Table2

Radioactive characteristics of natural uranium[51]

Characteristic Uranium series Actinium series

238234235

Nuclide half-life(years) 4.46×109245.5×103704×106 Natural abundance(%)99.27420.00540.7204

Type of emission Alpha Alpha Alpha

Decay energy(MeV) 4.270 4.859 4.679

%of?-activity0.01230.01270.0006

Total%of?-activity0.0256

water[43–45].Lower concentrations of uranium are found in basic rocks,while acidic rocks contain higher uranium concentrations [46,47].As Table1shows,the average radioactivity in soils is simi-lar to that in the rocks,usually bedrock,from which it derives[46]. The average radioactivity in soil of234U from Table1is0.6–1pCi/g. Since the activity of234U accounts for approximately one-half of the total activity in natural uranium,the value in Table1may be multiplied by two to obtain the total uranium radioactivity in soils (approximately1.2pCi/g)[46,47].However,there are wide varia-tions from the values presented in the table,particularly in areas where uranium minerals are more concentrated[4,37,51–55].

The mineralogy of uranium-containing minerals has been described by Frondel[48].In essentially all geological environ-ments,+4and+6are the most important oxidation states of uranium[49–51].The characteristics of naturally occurring ura-nium are shown in Table2.

Primordial uranium consists of three isotopes,238U and234U from the uranium series and235U from the actinium series.In nature,an imbalance between234U and238U may exist due to alpha particle withdraw from the decay of238U that increases the availability of234U for transport through geological processes.

Almost all uranium as found in nature is the isotope238U. It undergoes radioactive decay into a long series of13different radionuclides before?nally reaching a stable state in206Pb.These radionuclides emit alpha or beta radiation and some also emit gamma radiation of widely varying energies[4,37,55].The ratio of 234U to238U would be expected to be unity as long as the uranium stays locked inside undisturbed crustal rock in secular equilibrium with its progeny,but measurements show that the ratio is typically different than unity[55–57].This disequilibrium occurs when the rock is disturbed by chemical or physical changes involving water. These processes can change the uranium isotope ratios in air,soil and water.

Table1

Average radioactivity of uranium in several types of rocks and soils[46]

Material238U(pCi/g)Series equilibrium radioactivity

Total alpha emission Total beta emission Total gamma emission

Ingenious rocks

Basalt0.2–0.3 1.6–2.4 1.2–1.80.6–0.9

Ma?c0.2–0.3 1.6–2.4 1.2–1.80.6–0.9

Salic 1.3–1.610.4–12.87.8–9.6 3.9–4.8

Granite 1.08.0 6.0 3.0

Sedimentary rocks

Shale 1.08.0 6.0 3.0

Sandstones 1.08.0 6.0 3.0

Clean quartz0.2–0.3 1.6–2.4 1.2–1.80.6–0.9

Dirty quartz 1.08.0 6.0 3.0

Arkose0.3–0.7 2.4–5.6 1.8–4.20.9–2.1

Beach sands 1.08.0 6.0 3.0

Carbonate rocks0.7 5.6 4.2 2.7

Soils0.6 4.8 3.6 1.8

478M.Gavrilescu et al./Journal of Hazardous Materials 163(2009)475–510

Table 3

Normalized uranium ef?uent discharges from various activities involving uranium [58]

Uranium-238Curies per GWy(e)Atmospheric releases Minning –

Milling

1.8×10?2Mill tailings 1.9×10?5Conversion

2.0×10?3Enrichment 9.9×10?4Fabrication 2.0×10?5Liquid releases Conversion 2.2×10?2Enrichment 9.9×10?3Fabrication

9.9×10?3

The uranium present in the rocks and soil as a natural con-stituent represents natural background levels.Natural processes of wind and water erosion,dissolution,precipitation,and volcanic action acting on natural uranium in rock and soil redistribute far more uranium in the total environment than the industries in the nuclear fuel cycle.However,those industries may release large quantities of uranium in speci?c locations,mainly in the form of solids placed on tailings piles,followed by liquids released to tailings ponds and then airborne releases,both directly from the facilities and by wind erosion of the tailings piles [55–58](Table 3).A major localized source of enhanced natural uranium can result from mining and milling operations (Table 3).As part of nuclear fuel cycle,uranium conversion,uranium enrichment and fuel fab-rication facilities also release small amounts of uranium to the atmosphere [55–60](Table 3and Fig.2)

Contamination of the soil can occur either from deposition of uranium originally discharged into the atmosphere,or from waste products discharged directly into or on the ground (e.g.,water

containing uranium from either underground or open-pit mines).Examples of industrial activities that may result in soil deposition include uranium mining and milling,uranium processing,phos-phate mining,heavy metal mining,coal use and inappropriate waste disposal (Fig.2).

The contamination could be speci?c for various locations,depending on the contamination source and this lead to unam-biguous and signi?cant effort for conditioning,treatment,storage and safe disposal of nuclear waste at the repository [58].Available data on concentrations of uranium in different places con?rm these conclusions and reveals the fact that efforts have to be devoted for remediation and for public health preservation.Some American contaminated sites are relevant from this perspective [1,10,44,45,56,58](https://www.sodocs.net/doc/299645309.html,/toxpro?les/tp150-c5.pdf ;https://www.sodocs.net/doc/299645309.html,/superfund/sites/npl/nar1605.htm ):?concentrations of uranium in Louisiana soils ranged from 2.35to 3.98?g/g (average radioactivity 1.6–2.7pCi/g);

?uranium concentrations in phosphate rocks in north and central Florida ranged from 6.8to 124?g/g (4.5–83.4pCi/g);

?soil samples adjacent to Los Alamos,NM,taken during 1974–1977contained total uranium in the range of 0.1–5.1?g/g (0.067–3.4pCi/g),with a mean concentration of 2.4?g/g (1.6pCi/g);

?the concentrations of uranium in soils adjacent to the Hanford Fuel Fabrication Facility near Richland,WA,that were collected during 1978–1981ranged from 0.76to 4.6?g/g (0.51–3.1pCi/g),with a median

value of 1.8?g/g (1.2pCi/g);

?the control samples for the Hanford Fuel Fabrication Study contained uranium at concentrations of 0.32–1.128?g/g (0.21–0.86pCi/g),with a median value of 0.73?g/g (0.49pCi/g);?uranium in the soil of the Paducah Gaseous Diffusion Plant in Kentucky ranged from 4.9to 7.1?g/g (3.3–4.8pCi/g),whereas off-

Fig.2.Activities with impact on soil contamination with uranium and uranium compounds [55–60].

M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510479

site samples taken as far as12miles away contained uranium at levels of6.4–9.0?g/g(3.8–6.0pCi/g);

?soil monitoring data from the area surrounding the Feed Material Production Center at Fernald,OH,showed that the uranium con-centrations within an8km2area were between4.5and34?g/g (3–23pCi/g)compared to a mean of3.3?g/g(2.2pCi/g)for natu-ral background levels;

?uranium levels in surface soils at the Fernald site as high as50 times natural background levels.

2.2.Depleted uranium

Depleted uranium results as a byproduct during the process-ing of natural uranium,which makes it suitable for use as fuel in nuclear power plants or as a component in nuclear weapons[4,61]. Studies on the radiological and chemical properties of depleted uranium showed that they can be compared to those of natural uranium,which is all over present in soil.Natural uranium has the same chemotoxicity,but its radiotoxicity is60%higher[35,61]. Some studies revealed that the external exposure to radiation from depleted uranium is generally not major concern,so that depleted uranium is not a signi?cant health hazard if it is not taken into the body.Natural and depleted uranium is much more likely to be chemical than radiation hazardous[35,39,54,55,62,63].Some studies have however shown that exposure to intact depleted ura-nium weapons systems,both munitions and armor,pose very little risk from external radiation[39].Also,it was found that the234U that remains in depleted uranium emits a small amount of low-energy gamma radiation[32,35].Even if allowed to enter the body, depleted uranium,like natural uranium,has the potential for both chemical and radiological toxicity,with the two important target organs being the kidneys and the lungs[35,42,64].Some published data refer to the toxic effects of depleted uranium on reproduction and development,as well as on risk of leukemia and central nervous system[65–69].The relative contribution of each pathway to the total uptake into the body depends on the physical and chemical nature of the uranium,as well as the level and duration of exposure [32,53,70,71].

2.3.Chemical forms of uranium

Uranium can be found in soil as sorbed(both on soil parti-cles and pore water),complexed,precipitated and reduced forms, all of which have various impacts on its mobility and fate in the soil environment[72].It can exist in many chemical forms [4,37,54,55,61,69,73,74].

In nature,uranium is generally found as an oxide,such as in the olive-green-colored mineral pitchblende,which contains triu-ranium octaoxide(U3O8).In soil,uranium is typically in an oxidized form,and in water,it is usually present as a uranyl hydroxyl car-bonate complex[37,75,76].Uranium in ores can be extracted and chemically converted into uranium dioxide(UO2)or other chemical forms usable in industry.When re?ned,uranium is a silvery-white metal with very high density(being65%denser than lead).

Uranium dioxide(UO2)is the chemical form most often used for nuclear reactor fuel.Uranium–?uorine compounds are also com-mon in uranium processing,with uranium hexa?uoride(UF6)being the form used in the gaseous diffusion enrichment process.Ura-nium tetra?uoride(UF4)is frequently produced as an intermediate in the processing of uranium.As noted above,in its pure form, uranium is a silver-colored metal.Because several of these com-pounds might be used or produced during the conversion process,a brief description of the physical and chemical properties is provided below.

The mobility of uranium in soil and its vertical transport(leach-ing)to groundwater depend on properties of the soil such as pH,oxidation–reduction potential,concentration of complexing anions,porosity of the soil,soil particle size and sorption proper-ties,as well as the amount of water available[57,77].Retention of uranium by the soil may be due to adsorption,chemisorption,ion exchange or a combination of mechanisms[77].Any soil property that alters the sorption mechanism will also alter the mobility of uranium in the soil.

Complexation and redox reactions control the mobility of ura-nium in the environment[78].Uranium can exist in the+3,+4,+5 and+6oxidation states.In aqueous media only U(IV)and U(VI) are stable.The primary abiotic and biological processes that trans-form uranium in soil are oxidation–reduction reactions that convert U(VI)(soluble)to U(IV)(insoluble)[79].Further abiotic and bio-logical processes that can transform uranium in the environment are the reactions that form complexes with inorganic and organic ligands.

Some compounds,such as UCI4,decompose in aqueous media to the U(VI).In acid solution and in the body,the oxygen-containing cation UO22+,where uranium has the oxidation state VI,is the pre-dominant form.In general,hexavalent uranium compounds are the most soluble.

The reduction of U(VI)to U(IV)by abiotic and biotic processes, as well as its re-oxidation has received considerable attention because the oxidation state of uranium has a signi?cant effect on its mobility in the natural environment.Uranium exists in solution predominantly as UO22+and as soluble carbonate com-plexes(UO2)2CO3(OH)3?,UO2CO3?,UO2(CO3)22?,UO2(CO3)34?and possibly(UO2)3(CO3)66?[80–82].Between pH4.0and7.5, the pH range of most soils,U(VI)exists primarily in hydrolyzed forms.Uranium(VI),i.e.,uranyl,uranium will exist in the+6oxi-dation state under oxidizing to mildly reducing environments. Uranium(IV)is stable under reducing conditions and is considered relatively immobile because U(IV)forms sparingly soluble miner-als,such as uraninite(UO2).Dissolved U(III)easily oxidizes to U(IV) under most reducing conditions found in nature.The U(V)aqueous species(UO3+)readily disproportionates to U(IV)and U(VI).Under reducing conditions,the speciation of U(IV)is dominated by the neutral aqueous species U(OH)40(aq)at pH values greater than2 [83,84].

The estimates of the solubilities and the speciation of uranium (nature and concentration species)are predicted from thermody-namic data,taking into account the presence of inorganic ligands in the groundwaters studied,mainly[OH]?,[HCO3]?,[CO3]2?, [H2PO4]?[HPO4]2?,[PO4]3?,[SO4]2?(in case of disposal in rock-salt formation)and the properties of these waters(redox potential) [85].

Eh–pH-diagrams show the thermodynamic stability areas of dif-ferent species in an aqueous solution.Stability areas are presented as a function of pH and electrochemical potential https://www.sodocs.net/doc/299645309.html,ually the upper and lower stability limits of water are also shown in the diagrams with dotted lines.Traditionally these diagrams have been taken from different handbooks[Pourbaix Atlas Handbook]. In most handbooks these diagrams are available only for a limited number of temperatures,concentrations and element combina-tions[83,84,86,87].

The distribution of uranium species at25?C as a function of pH for both oxidizing and moderately reducing conditions is illustrated in Fig.3,which further emphasizes that hydrolysis species and car-bonate complexes are of primary importance.The major oxidation of U(IV)and U(V)as states of uranium is also apparent.

Uranium(IV)is very insoluble forming uraninite(UO2)or a mixed valence oxide phase like UO2.25or U02.33.Uranium(VI)is much more soluble and mobile.Uranium(VI)also forms soluble

480M.Gavrilescu et al./Journal of Hazardous Materials 163(2009)

475–510

Fig.3.Eh–pH and uranium species distributions as a function on pH for oxidizing and mildly reducing conditions (adapted upon [88,89]).

complexes with carbonate anions in natural waters.The aque-ous speciation of U(VI)in carbonate-containing waters at near neutral and basic higher pH values is dominated by a series of strong anionic aqueous carbonate complexes [e.g.,UO 2CO 30(aq),UO 2(CO3)22?and UO 2(CO 3)34?].Fig.3shows that the aque-ous complex [UO 2(CO 3)2]2?is the predominant form of uranium between pH 7and 8in an oxidized environment.Numerous inves-tigations of the adsorption of uranium on soils and minerals have shown that carbonate complexing appreciably reduces adsorption of uranium leading to its release from soils [90–93].Eh–pH dia-gram for uranium shows the presence of solid phase at low Eh and predominance of dissolved uranium carbonate complexes at high Eh values.The upper diagonal dashed line is the superior stability limit of water and represents oxidizing conditions,while the lower diagonal dashed line represents the inferior limit of water stability under reducing conditions.When Eh values are above 0.25V and pH between 7and 8,uranium will be in the oxidized valence state (VI).Also,when Eh values are higher than 0.25V (usually for pH ranging between 1and 5),uranium is in the valence state (VI),as uranyl ion [UO]2+.In alkaline medium,carbonate is the most sig-ni?cant ligand (in natural water)and the greater solubility of the U(VI)ion is in part due to its tendency to form anionic carbonate complexes [78,90–93].

The dependency of the speciation distribution on pH and carbon dioxide concentration in a closed system is shown in Fig.4.The formation of carbonate complexes can change the stability ?eld of U(VI).These U(VI)complexes may exist in alkaline conditions and high carbonate concentrations even in reducing conditions [94–96].

Uranyl hydroxy complexes such as UO 2(OH)+and (UO 2)3(OH)5+are also formed,but generally in smaller amounts except at high temperature or in carbonate-depleted alkaline water.In reducing water,the U(IV)hydrolysis leads to U(OH)40[83,84].The solubil-ity of reduced uranium is low and it has a strong tendency to hydrolyse,forming colloids,especially when environmental con-ditions change.High concentration of inorganic salts hinders the formation of colloids,while colloids already present may coagulate [95,97].

In dolomitic water Eh–pH diagram for uranium (0.01–0.5mg U/L)is more complicated due to the presence of calcium

M.Gavrilescu et al./Journal of Hazardous Materials 163(2009)475–510

481

Fig.4.The effect of pH and concentration of carbon dioxide (log C )on the speciation of uranium in ground water assumed as a closed system [94].

and magnesium ions,and other possible complex with sulfate [98–100].A diagram for a real dolomitic system is presented in Fig.5.

pH-drop below 6(under normal oxidizing conditions)might allow for uranium to stay in solution as [(UO 2)3OH]5+instead of precipitation as a carbonate [99,100].

In addition to dissolved carbonate,uranium can also form stable complexes with other naturally occurring inorganic and organic lig-ands such as phosphate complexes [UO 2HPO 40(aq)and UO 2PO 4?](Fig.6)[101].Complexes with sulfate (Fig.7)[102],?uoride

and

Fig.5.Eh–pH diagram for uranium (0.01–0.5mg U/L)in dolomitic water (adapted upon [100]

Fig.6.Calculated uranium speciation in the system UO 2–PO 4–CO 3–OH–H 2O at over-saturation at t =25?C [101].

possibly chloride are potentially important uranyl species where concentrations of these anions are high.However,their stability is considerably less than the carbonate and phosphate complexes [82]

Fig.7.Eh–pH diagram and uranium speciation in present of sulfates at t =25?C (concentrations of U-ions:0.01mg/L;concentrations of sulfate-ions:0.1mg/L)[102].

(1)UO 2+

;(2)U(SO 4)2+;(3)U 4+;(4)UO 2(SO 4)0;(5)U(SO 4)02;(6)UO 2;(7)UO 2(SO)2?;(8)UO 2(OH)2H 2O;(9)U 3O 8;(10)U 4O 9.

482M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510

Eh–pH diagram from Fig.7shows that,if the pH of uranium-bearing aqueous medium is increased,an insoluble uranate precipitate(namely“yellow cake”)is formed.Also,this diagram represents a useful guideline regarding the regions of pH and oxi-dation potential in which simple uranium oxide,ions in solutions and insoluble uranates exist[102].

Organic complexes may also be important to uranium aqueous chemistry,thereby increasing their solubility and mobility in soil. The uncomplexed uranyl ion has a greater tendency to form com-plexes with fulvic and humic acids than many other metals with a +2valence[103].In particular,the presence of organic substances and/or colloids in the groundwater increases the complexity of the system.Humic substances formed by the degradation of plants and animals constitute a heterogeneous category of compounds with a complex forming capacity due to the presence of carboxylic, hydroxy and phenolic groups[4].Dissolved humic substances (humic and fulvic acids)proved to be strong complexing agents for many trace metals in the environment,forming also stable com-plexes or chelates with radionuclides[104,105].These substances can be found as dissolved in surface waters as well as in ground-waters,in concentrations ranging from less than1mg(TOC)/L to more than100mg(TOC)/L.It has been shown that the binding of metals to humic acid apparently occurs at binding sites with rel-atively well-de?ned complex formation constants[104].Uranium mineral precipitation and co-precipitation processes may also be important during remediation for some environmental conditions, and several uranium(co)precipitates may form,depending on the geochemical conditions[106,107].Solubility processes may also be particularly important for the environmental behavior of U(VI) under oxidizing conditions in those soils that become partially sat-urated with water or completely dry,when the concentration of uranium in the residue pore?uids may exceed the solubility limits for U(VI)-containing[84].

2.3.1.Uranium oxides

The most common forms of uranium oxide are U3O8and UO2. Both oxide forms are solids with a low solubility in water and relatively stable over a wide range of environmental conditions [61,108].U3O8is the most stable form of uranium and is the form found in nature.The most common form of U3O8is yellow cake, a solid named for its characteristic color that is produced during the uranium mining and milling process.UO2is a solid ceramic material and is the form in which uranium is most commonly used as a nuclear reactor fuel[4].At ambient temperatures,UO2will gradually convert to U3O8.Uranium oxides are extremely stable in the environment and are thus generally considered the preferred chemical form for storage or disposal[61].

2.3.2.Uranium hexa?uoride

UF6is the chemical form of uranium,which is used during the uranium enrichment process[65].Within a reasonable range of temperature and pressure,it can be solid,liquid or gaseous[109]. At ambient conditions,UF6is a volatile,white,crystalline solid. Solid UF6is readily transformed into the gaseous or liquid states by the application of heat.All three phases–solid,liquid and gas –coexist at64?C(the triple point).Only the gaseous phase exists above230?C,the critical temperature,at which the critical pressure is4.61mPa.The vapor pressure above the solid reaches0.1mPa at 56?C,the sublimation temperature.

Solid UF6is a white,dense,crystalline material that resembles rock salt.UF6does not react with oxygen,nitrogen,carbon dioxide or dry air,but it does react with water or water vapor(including humidity in the air)[110].When UF6comes into contact with water, such as water vapor in the air,the UF6and water react,forming cor-rosive hydrogen?uoride(HF)and a uranium–?uoride compound called uranyl?uoride(UO2F2).For this reason,UF6is always han-dled in leak-tight containers and processing equipment.Although very convenient for processing,UF6is not considered a preferred form for long-term storage or disposal because of its relative insta-bility[61].

2.3.3.Uranium tetra?uoride

UF4is often called green salt because of its characteristic color.It is generally an intermediate in the conversion of UF6to U3O8,UO2 or uranium metal because it can be readily converted to any of these forms.UF4is a solid composed of agglomerating particles with a texture similar to baking soda.It is non-volatile,non-hydroscopic, but only slightly soluble in water[61].After exposure to water,UF4 slowly dissolves and undergoes hydrolysis,forming any of several possible uranium compounds and hydrogen?uoride[110].The time for hydrolysis can be lengthy.Although not as stable as the ura-nium oxides,several recent studies have indicated that UF4may be suitable for disposal.

2.3.4.Uranium metal

Uranium metal is heavy,silvery white,malleable,ductile and softer than steel.It is one of the most dense materials known (19g/cm3),being1.6times more dense than lead[37].Uranium metal is not as stable as U3O8or UO2because it is subject to surface oxidation.It blurs in air,with the oxide?lm preventing further oxi-dation of bulk metal at room temperature.Water attacks uranium metal slowly at room temperature and rapidly at higher tempera-tures.Uranium metal powder or chips will ignite spontaneously in air at ambient temperature[111].

Some characteristics of uranium compounds,most of them determinant for choosing the remediation technique,are summed up in Table4[4,37,61,71,112–117].

2.4.Uranium compounds toxicity

The toxic effects generated by uranium exposure are based on its chemical and radioactive characteristics.Toxicity is closely related to solubility,i.e.,the more soluble the uranium compound is,the more toxic it becomes[118].

The permissible levels for soluble compounds are based on chemical toxicity,whereas the permissible body level for insoluble compounds is based on radiotoxicity.

Several possible health effects are associated with human expo-sure to radiation from uranium.Because all uranium isotopes mainly emit alpha particles that have little penetrating ability,the main radiation hazard from uranium occurs when uranium com-pounds are ingested or inhaled[118–120].

The less water-soluble compounds(uranium trioxide,sodium diuranate,ammonium diuranate)were of moderate-to-low toxicity,while the insoluble compounds(uranium tetra?uo-ride,uranium dioxide,uranium peroxide,triuranium octaoxide) were primarily pulmonary toxicants.Soluble uranium com-pounds are toxic both when breathed or ingested.Generally, hexavalent uranium,which forms soluble compounds,is more likely to be a systemic toxicant than the less soluble tetrava-lent uranium[98].The most soluble uranium compounds are UF6,UO2(NO3)2,UO2Cl2,UO2F2and uranyl acetates,sulfates and carbonates.Some moderately soluble compounds are UF4, UO2,UO4,(NH4)2U2O7,UO3and uranyl nitrates.The rapid pas-sage of soluble uranium compounds through the body tends to allow relatively large amounts to be absorbed.Soluble ura-nium compounds may(also)be absorbed through the skin.The least soluble compounds are high-?red UO2,U3O8,and uranium hydrides and carbides.The high toxicity effect of insoluble com-pounds is largely due to lung irradiation by inhaled particles.This

M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510483

Table4

Physical characteristics of uranium compounds[61]

Compound Melting point(?C)Density(g/cm3)Properties

Crystal particle Bulk

UF6Uranium hexa?uoride64.1 4.68 4.6Soluble in water,decomposes to UO2F2high

chemically toxic

UF4Uranium tetra?uoride960±5 6.7 2.0–4.5Very slightly soluble in water at ambiental

temperature

UO2F2Uranyl?uoride Decomposes to U3O8at300 6.37～2.6Soluble in water at ambiental temperature

UO2Cl2Uranyl chloride Decomposes Decomposes in the presence of light,exhibits

?uorescence,highly toxic

U3O8Triuranium octaoxide Decomposes to UO2at13008.30 1.5–4.0Very stable,has a low solubility in water

UO2Uranium dioxide2878±2010.96 2.0–5.0Insoluble in water,highly toxic and

spontaneously?ammable,used in weapons in

place of lead in the Gulf War(also called

uranium oxide,uranitite)

UO3Uranium trioxide～200–6508.0 5.5–8.7Insoluble in water,poisonous,decomposes

when heated(also called uranyl oxide)

UO2(NO3)2·2H2O Uranium nitrate118(decomposes) 2.81Dissolves in water to form a weak solution of

nitric acid,the reaction is not hazardous,

oxidizing and highly toxic compound

Uranium metal113219.0519Insoluble

material is transferred from the lungs of animals quite slowly (https://www.sodocs.net/doc/299645309.html,/uranium/guide/ucompound/health/index. cfm).

Of the most important uranium compounds used industrially, UF6and UO2(NO3)2·6H20are the most toxic,whereas UO3is only moderately toxic,and UO2,U308and UF4are considered low in toxicity.

A variety of materials on radiation effects,obtained from animal experiments and studies in humans were published[3,119–121].As it has already highlighted above,from literature data it results that all uranium mixtures,natural,depleted or enriched,are considered chemical toxins that may result in nephrotoxic effects[3,122,123]. The majority of the uranium deposited in the kidney is removed with a biological halftime of6days and the remainder with a1500 d half-time.No permanent effects have been observed in any expo-sure case[3].

The presence of high levels of uranium(U)compounds in the human body has been reported to affect renal functions and,at very high concentrations,lead to kidney failure[124,125].The pri-mary pathways of U entrance into the human body are inhalation of contaminated dust or ingestion of contaminated water.The chem-ical toxicity of uranium as a heavy metal has raised public health concerns,especially in areas where contamination of local soils and groundwater from radioactive material has taken place.As a result, there is strong interest in remediation of uranium and depleted uranium laden areas[125].

3.Methods and techniques for uranium removal

3.1.General description

The objective of any remedial action is to reduce the risks to human health,environment and property to acceptable levels by removing or reducing the source of contamination or by blocking exposure pathways.Once the decision has been made that some remedial action is necessary,there are various potential options for achieving that objective[5,9,126,127].

Radionuclides and heavy metals are retained by soil in three ways[11,128,129]:

?adsorption onto the surface of mineral particles;?complexation by humic substances in organic particles;?precipitation reaction.

As was highlighted above,the mobility of uranium in soil is mainly controlled by complexation and redox reactions [78,130,131]:

?complexation leads to mobile species or precipitation of U-bearing minerals;

?redox reactions change the solubility between the two major oxi-dation states:U(IV)–U(VI):

o reduction of U(VI)to U(IV)immobilizes uranium;

o oxidation of U(IV)to U(VI)mobilizes uranium because of the dissolution of U(IV)bearing minerals.

These reactions are the basis for certain remediation tech-nologies,their combination determining the mobility and fate of uranium.Furthermore,the techniques and methods for uranium removal from soil are selected according to the type of contami-nants present,the behavior of the contaminants in the environment and the exposure pathways[5,9].For sites with mixed contamina-tion,it is often necessary to use several remediation technologies, sometimes in series,i.e.,treatment trains,to effectively address risk from the radioactive,chemical and physical hazards that could be present.In addition,sites may have contamination in different media[17].It is not uncommon,for example,to have also ground-water contamination on sites with extensive soil contamination,so that a range of technologies is needed for remediation of the various contamination problems[5,132].

There are three basic options for any intended remedial actions: monitored non-intervention,containment or removal,summarized in Table5and various techniques/technologies are associated,such as:

?separation;

?concentration and/or volume reduction;

?immobilization/sequestration.

In contrast with organic compounds,radionuclides in general and uranium in particular,cannot be commonly destroyed or degraded.

Each one of the above fundamental technical choices will direct decision makers to substantially different paths with regard to their subsequent choices,actions and potential results,making available signi?cantly different technological options for application,within a remediation program,which involves multidisciplinary environ-

488M.Gavrilescu et al./Journal of Hazardous Materials 163(2009)

475–510

Fig.8.Classi?cation of remediation techniques by function [133].

mental research on characterization,monitoring,modelling and technologies for remediation (Fig.8).

Any measurable remediation objective has to consider several factors,which could induce an impact on the decision making process have to be considered,like basic evaluation criteria that include engineering and non-engineering reasons for ensuring the achievability of the “cheaper,smarter and cleaner”soil remediation philosophy,such as [20,28,132,141–143]:?cleanup goals;

?form and concentration of pollutants;

?volume and physical/chemical properties of the polluted soils;?remediation effectiveness;

?designated use of the cleaned site;

?cost associated with the remediation program;

?occupational safety and health risks associated with the technol-ogy;

?potential secondary environmental impacts (collateral damage);?prior experience with the application of the technology;?sustainability of any necessary institutional control;?

socio-economic considerations.

Fig.9is a schematic representation of the relations between evaluation of remediation alternatives and remediation aims and options as a support for decisions making about implementation,so that the remediation performances be ful?lled.

The costs for implementing available technologies will vary sig-ni?cantly between sites because costs are in?uenced by a wide variety of factors.Fig.10represents the ranges of operating costs that have been observed for remediation of metals-contaminated soils by a number of techniques.

Remediation technologies available for treating uranium con-taminated soils and groundwater could be applied as either ex situ or in situ techniques [132,144–146].

In situ techniques are generally preferred because they cause less site disturbance,less contaminant exposure to the environ-mental professionals and public in the vicinity,and they are often less complicated and more economical [141–146].Also,because radionuclides are not destroyed,ex situ remediation requires sites for waste disposal,which have to meet special acceptance criteria and are limited [147].

A series of bench-scale studies were conducted to evaluate the in?uence of some factors affecting uranium removal from soils,such as soil characteristics,time,temperature,attrition scrubbing,pH and reagent concentrations,oxidizing and reducing chemical environments [143–145,148].

Soil characteristics affect the remediation process,since soil behaves as a complex sorbent.Uranium preferentially adheres to soil particles,with a soil concentration typically about 35times higher than that in the interstitial water.Concentration ratios are usually much higher for clay soils (e.g.,1600).The concentrations and distributions of uranium among particle size fractions of the soils vary signi?cantly,as is shown in Table 6.Data in Table 6are for particle size fractions of the some soils after wet sieving and sepa-ration of the clay fractions ?0.002mm diameter following methods according to some authors [148–150].

When mining soils are remediated,it is necessary to discern that uranium mining wastes comprise several types of waste [134]:?overburden (soil and rock that is covering a deposit of ore,such as uranium.It usually contains at least trace amounts of the ore plus radioactive decay products);

M.Gavrilescu et al./Journal of Hazardous Materials 163(2009)475–510

489

Fig.9.Remediation alternative evaluation in relation with aims and performance [adapted upon 139–143].

?unreclaimed,subeconomic ores (ores that have too little uranium to be pro?table,called “protores);

?“barren”rock (rock containing no ore);?drill cuttings.

The Eh–pH diagrams (Figs.3–7)indicate that sorption onto soil can be strongly in?uenced by the pH of the soil solution and,to a lesser extent,by the presence of calcium,suggesting speci?c chem-ical interactions between U(VI)and the soil matrix,so that the remediation process will depend on the same factors like

those

Fig.10.Estimated operating costs of some available remediation technologies for contaminated soils (https://www.sodocs.net/doc/299645309.html,/download/toolkity/metals.pdf ).

in?uencing uranium solubility [151,152].Therefore,soil remedia-tion techniques will be chosen considering sorption,complexation and redox reactions as the dominant mechanisms responsible for the reduction of mobility,toxicity or bioavailability of radionuclide contaminants [10,78,130,131,153,154].

The sorptive phases that could control U(VI)sorption onto the soil are the iron and manganese oxide coatings and the clay frac-tion.Speci?cally,hydroxyl groups on the oxide surface,–SOH,are expected to be the dominant sorption sites [155].

Hydroxylated groups (–SiOH and –AlOH)situated along the edges of clay minerals can also be signi?cant sorption sites [156].Sorption onto such variable charge sites depends on the pH of the soil solution.

Some authors reported adsorption edges at pH 4–5working with sorbents as goethite and ferrihydrite [90,157,158];the lower sorption edge could be caused by the heterogeneity of the soil:iron and manganese oxides,clays and a small fraction of organic matter are all present.

The pH dependence of the sorption process indicates that pro-tons (H +)compete with U(VI)for sorption sites (surface hydroxyl groups,–SOH);at low pH,H +is the key sorbing species,forming positively charged diprotonated sites (–SOH 2+).As the pH increases,U(VI)ions displace H +and bind to OH groups on the surface.The U(VI)reaction with those surface hydroxyl groups is similar to the hydrolysis reaction observed in aqueous solution only.

Sorption of U(VI)–CO 32?complexes is responsible for the large degree of U(VI)removal from the aqueous solution observed near neutral pH [98–100].The identity of these U(VI)–carbonate surface species was analyzed by several authors:Hsi and Langmuir [158]have discussed sorption of [UO 2(CO 3)SO 3]2?and [UO 2(CO 3)3]4?onto goethite;Payne and Waite [159]have suggested UO 2CO 3,

490M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510

Table6

Concentrations dry weight basis and distribution of uranium in soils[149,150]

Soil,uranium concentration(mg kg?1)Size fraction(mm)Particle size

distribution(wt%)Uranium concentration

(mg kg?1)

Uranium contribution by

size fraction(wt%)

Y-12landfarm >2.00 1.8442 4.3 2.00–0.07517.536133.8 0.075–0.02034.131 5.8 0.020–0.00230.418029.3?0.00216.231226.9

Incinerator soil-538

2.00–0.05312.5103327 0.53–0.0027

3.928644?0.00213.6101929

Minning soil-446

2.00–0.05322.61177 0.053–0.00256.523937?0.00220.998356

[UO2(CO3)2]2?and[UO2(CO3)3]4?sorption onto amorphous fer-ric oxyhydroxide(Fe2O3·H2O);Waite et al.[90]have proposed sorption of UO2CO3onto ferrihydrite;Duff and Amrhein[81]have found that[(UO2)2CO3(OH)3]?is the sorbing species in the pres-ence of goethite.There is a number of spectroscopic studies that provide direct evidence for the formation of ternary U–carbonato species[SO2UO2(CO3)x on mineral surface such as hematite and silica[160,161].

Several investigations on the removal of uranium from arti?-cially contaminated soils as well as from anthropogenic sources, such as mine tailings and DU processing facilities,revealed that the application of any remedial technology for soils contaminated with uranium must take into account the potential of exposure to workers(as a consequence of the presence of radionuclides and the type and energy of radiation emitted)and the need to keep the exposure as low as reasonable achievable[147,162–164].The ulti-mate goal is to develop technologies that can further reduce risks, reduce cleanup costs and reduce the volume of remaining contam-inated soil[15].These involve technologies assessment based on some reasons,which can include[15,141,146,147]:?accounting of contaminant distribution,soil characteristics and adhesion/absorption characteristics of contaminants on soil par-ticles;

?evaluation of physical,chemical and biological processes that should have potential to remediate radioactive contaminated soils;

?ranking of technologies based on technical value,potential expe-rience and facility of implementation;

?engineering evaluation of technologies to determine scale-up potential and cost effectiveness;

?identi?cation of secondary waste treatment needs for full-scale implementation;

?identi?cation of dif?culties and research needed to overcome technology limitations.

3.2.Natural attenuation

The long-term restorations of ecosystems and contaminated sites have been attributed to natural attenuation processes.

Natural attenuation is the process by which the concentration of environmental pollution is reduced to an acceptable level by natural processes.According to the USEPA[47],natural attenu-ation is the“use of natural processes to contain the spread of the contamination from chemical spills and reduce the concen-tration and amount of pollutants at contaminated sites”.It can also be termed as intrinsic remediation,bio-attenuation and intrin-sic bioremediation[164,165,166].Natural attenuation is considered to be the least invasive approach to environmental remediation.Generally,these processes occur in soil,groundwater,and sur-face water systems at all sites at varying rates and degrees of effectiveness to decrease the concentrations of organic and inor-ganic contaminants[152,166,167,168].The ef?ciency of this mode of remediation will vary based on the biological and chemical nature of the contaminated site.The physical,chemical and biological processes,the rate and extent to which these natural attenua-tion processes occur are different for each contaminant and site hydrologic and geochemical conditions.Under certain conditions (e.g.,through sorption or oxidation–reduction reactions),natural attenuation could effectively reduce the dissolved concentrations and/or toxic forms of inorganic contaminants in groundwater and soil[169].

Natural attenuation of radionuclides can occur through a num-ber of sorption processes,including incorporation of contaminants into a mineral in the soil or an aquifer or by being entrapped in a rock pore[170].Whereas natural attenuation of organic con-taminants means breakdown and elimination by microorganisms, natural attenuation of radionuclides involves their encasing in a mineral where they will not escape unless chemical conditions change dramatically[135,152,166,170,171].

A number of investigations were performed concerning the natural attenuation of uranium in a tailings disposal site,which revealed that a number of radionuclides exhibit signi?cant migra-tion potential in the presence of aqueous,low molecular weight organic compounds immobile organic matter in the form of peat or organic-rich horizons in soils and sediments that may pro-vide excellent substrates for radionuclide retention[168,172–176]. When uranium is dissolved in groundwater,it can be attracted to natural iron coatings located on walls of rocks through which the water is?owing,and bind to the iron coating and then move into microscopic rock pore and then incorporated into the iron coating [176,177,178].

The monitoring of the process involves the study of the rate and extent of irreversible adsorption of uranium,the fraction of uranium in aquifers associated with the phenomenon,and the degree of irreversible adsorption of uranium required to reduce the amount of uranium under the safety levels[179,180].Microorgan-isms appear to be excellent indicators of soil health because they respond to changes in the soil ecosystem quickly[181].

Phytostabilization strategies may be suitable to reduce the dis-persion of uranium and the overall risks of U-contaminated soils. Plants grown in soils with high carbonate–U fractions can accu-mulate the most U in shoot sand roots,while in clay soils with high Fe,Mn anorganic fractions this process is low[148].Macro-phytes in natural and constructed wetlands can in?uence uranium immobilization either directly by uptake and accumulation and/or indirectly(biomass production—litterfall and root turnover decom-position).

M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510491

A number of investigations on the natural attenuation of the uranium(U)load in the surface water in various environmental conditions(for example,within a humid forest in Japan)were per-formed[15,176,178,180,182].Surface water and sediments that had accumulated behind dams in the area were investigated in terms of their mineralogy and chemistry.The results of this investiga-tion indicate that U,which within the study area is derived from pegmatites at a mine,is attenuated by uptake onto the surface of organic material as well as by amorphous material that forms over time within the dammed sediments.In most cases costs only occur in connection with monitoring[177,179].

3.3.Physical processes

Physical processes include soil capping,soil washing,soil aer-ation and heat?ow,water storage and drainage,solidi?cation, solubilization and solute transport[28,183,184].

Land?lling of radionuclides is dif?cult and expensive and land disposal restrictions have to be taken into account,as well as other national and international regulations[147,185,186].

Soil capping is a strategy of radioactive waste containment,when buried waste is capped with layers of materials(even imperme-able)mainly to prevent surface water in?ltrations,although it does not fully solve the contamination problem and does not change the waste’s toxicity[184,187–191].In fact,caps are covers placed over land?lls and other waste areas,and are intended to isolate the waste.

Impermeable caps could be single of multi-layer clays,topped by plastic sheets,soil,etc.[184,187].Capping process can be structured in four phases[184,188–190]:

?mobilization(preparation of site for cap construction);?operational(actual cap construction);

?closure(installation of monitoring wells,decontamination and demobilization of equipment);

?post-closure(monitoring and long-term maintenance).

Capping technology has the advantage of little disturbance of contaminants as well as lower costs[184].Some disadvantages refer to caps degradation by cracking(especially in environments with freeze and thaw cycles)or weakening by penetration of plant roots, land?ll setting,etc.[191].

Soil-washing or soil-?ushing systems are designed to treat soils where the majority of the contaminants are concentrated in the ?ner-grained materials or on the surfaces of the larger soil par-ticles.Soil washing entails extraction of unwanted contaminants from soil with liquids,generally aqueous solution,when the con-taminants are separated from the soil matrix and transferred to the washing solution and then the washing solution is extracted from the soil.Water or liquid solutions,whether injected or in?l-trated into the contaminated area,mobilize the contaminant and are then collected and brought to the surface for disposal,recircu-lation,on-site treatment or reinjection[178].Some operational and performance criteria were used for this analysis,such as[192,193]:?removal ef?ciency,as the ratio of uranium activity in the treated soil to that in contaminated soil;

?ability to meet the standards;

?possibility to achieve the smallest volume of the treated soil so as to ensure off-site disposal.

The majority of soil-washing processes involve screening pro-cesses in order to separate the?ne contaminated particles[28,183].

Solidi?cation—the binding of a waste/soil into a solid mass can reduce its contaminant leaching potential.This process involves the generation of blocks of waste,where the radionuclides are kept mechanically within a solid matrix[147].Vitri?cation of molten glass is another solidi?cation method which uses heat of up to 1200?C to melt and convert waste into crystalline products.Also, stabilization reduces the solubility and/or chemical reactivity of a waste/https://www.sodocs.net/doc/299645309.html,ually,it entails the addition of various binders (cement,silicates)in order to limit the solubility and/or mobility of radionuclides[147].Both can be done in situ or ex situ on excavated materials by processing at a staging area either on site or off-site [28].Physical treatment processes can be sequenced in a treatment queue,such as:excavation,transportation to a vitri?cation site and vitri?cation/sequestration[109].

3.4.Chemical methods

Chemical processes for remediation of radionuclide pol-luted soils include chemical degradation/transformation, volatilization,oxidation/reduction,solubility processes and adsorption/desorption.

A variety of chemical remediation techniques are available for remediation of radionuclide-contaminated soils that can be grouped as

?chemical conversion into a water-soluble form;

?chemical immobilization.

Research has shown that there are at least three different forms of uranium in the contaminated soil:

?uranium(VI)phosphate minerals;

?reduced U(IV)phases;

?complexed U(VI)with soil organic matter;

?a small fraction of U(VI)sorbed onto soil minerals[72].

These methods are often expensive to apply and lack the speci-?city required to treat target metals against a background of competing ions[27,194,195].In addition,such approaches are not applicable to cost-effective remediation of large-scale subsurface contamination in situ.Also,the extraction media and procedures designed for a selective uranium removal have to preserve the physico-chemical characteristics of soils and avoid the generation of secondary waste forms,dif?cult to manage or dispose.

The removal procedures must guarantee a good mobility of ura-nium so that it would pass from the environmental component into another system[183,195].Four approaches to increase metal mobility in heavy metal and radionuclide polluted soils have been suggested:change in acidity,change in ionic strength,change in redox potential and formation of mobile complexes[27,28,196]. They are discussed in the following paragraphs.

Table7highlights some chemical processes used for extracting U from contaminated soils indicating that several highly ef?cient choices exist for the extraction of U from contaminated soils and other materials[197].Under ambient oxidizing conditions,U(VI) should be easily removed using bicarbonate,a strong inorganic acid or a weak organic acid(ascorbic,citric).Ebbs et al.[198]have examined the role of acidi?cation and chelating agents in the sol-ubilization of uranium(U)from contaminated soil and compared the two methods.

3.4.1.Chemical extraction

The chemical extraction process from contaminated soils involves the conversion of uranium into a water-soluble form, which is then extracted from the soil.An adequate uranium extrac-tion can be achieved if certain conditions are met[195,199,200]:

492M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510

Table7

Selected DU chemical soil extraction methods[197]

Total DU removed U content(mg/kg)Material Extraction method Overall percentage Reference

4201320Contaminated soil and ash0.1–0.5M NaHCO380[138] 95708a Acid/mixed/alkaline tailings,contaminated soil0.1M NaHCO320–94[162] 449732Contaminated soil0.2–0.6M citric acid85–99[163]–2629Radioactive waste4M HNO3+0.05M H3BO3>99[164]

a Values interpolated from publication.

?uranium solubilization by exposing it to the solution which con-tains the chelating ions(citrate,carbonate);

?availability of complexing anions,by controlling the solution chemistry,chemical environment and conditions(pH,time,tem-perature)and early uranium precipitation;

?uranium oxidation to the hexavalent state(in the presence of carbonate).

Using chelating agents to extract uranium from contaminated soils is considered to be a chemical treatment method[201–205].

U(VI)cationic complexes are abundant from low to alkaline pH (about pH8)(Eqs.(1)–(5)):

4H++UO22++2e?→2H2O(l)+U4+(1) UO22++2e?→UO2(s)(2) UO22++H2O(l)→H++UO2OH+(3) 3UO22++5H2O(l)(5H++[(UO2)3(OH)5]+(4) 3UO22++7H2O(l)(7H++[(UO2)3(OH)7]?(5) Chelating agents may be either organic or inorganic com-pounds.A number of inorganic chelators have been investigated for remediation and some of complexation constants for those chela-tors are now available[78,90–93,99–102,201].Polyphosphates are considered as the most ef?cient inorganic chelators.Their annual consumption is higher than that of organic chelating agents [200,201,202].Chelating compounds may be represented either using conventional empirical and structured formulas or some type formula as shown in Table8.

The strong chelators with target metals will have much greater solubility and stability(i.e.,stability constant p K)than other reac-tions with metals in the aqueous phase[200–203].This strength can be shown as p K chelators/p K natural ligands.The greater this ratio, the stronger this chelator will be.The stability of chelates is in?u-enced by a number of parameters.Several of the stability factors common to all chelate systems are the size and number of rings, substituents on the rings,and the nature of the metal and donor atoms.The role of acidi?cation and chelating agents in the solubi-lization of uranium(U)from contaminated soil was examined in a series of experiments.

3.4.1.1.Method(s)using sodium carbonate/bicarbonate.Carbon-ate/bicarbonate ions could lead to a rapid and greatly increased leaching and mobilization of U(VI)from a contaminated soil, depending on site-speci?c conditions[72,162,197].

Sodium bicarbonate has been used in the mining industry to extract U from carbonate bearing ore material.The bicarbonate ion forms strong aqueous complexes with U(VI)according to reactions (6)and(7)and enhances the dissolution of UO22+.

UO22+(aq)+2HCO3?(aq)→[UO2(CO3)2]2?(aq)+2H+(aq)(6) [UO2(CO3)2]2?(aq)+HCO3(aq)→[UO2(CO3)3]4?(aq)+H+(aq)(7)

This stable water-soluble complex forms easily under ambient conditions.Fig.11presents the dominating complexes of UO22+as a function of[CO3]2?[206–208].

Mason et al.[138]used NaHCO3solution as an alkaline treat-ment for U contaminated soils from a processing facility in OH, USA.The authors were able to recover80%of the total DU in the aqueous phase.Residual DU in the soil was determined to be com-prised of relatively insoluble minerals,including meta-autunite (Ca(UO2)2(PO4)2·x H2O,log K sp(25?C)=?48.5),uranium metaphos-phate(U(PO3)4)and uraninite(UO2).It was considered that the autunite was formed because the local soil had high phosphate content from prior pollution to the site.Mason et al.[138]indi-cated that ef?ciencies of75–90%corresponding approximately to the percentage of uranium in the oxidized state were achieved for the removal of uranium from contaminated soils(Ohio in USA) using0.5M sodium bicarbonate as the dominant reagent.

Sodium peroxide,Na2O2,was also added to the leaching process to promote oxidation of U(IV)by the following reactions:

Na2O2+2H2O(l)→2NaOH+H2O2(8) UO2(s)+H2O2+2H+→UO22++2H2O(l)(9) Use of sodium peroxide(oxidizing agent),improved uranium removal due to oxidation of U(IV),enhancing the solubility of the uranium[28].The oxidation of U(IV)to U(VI)occurred by a two electron transfer from U(IV)to H2O2[209].The resulting uranyl ion (UO22+)was then available for subsequent complexation with HCO3 ions by reaction(1).A10:1molar ratio of oxidant to U enhanced

the extraction of DU by20%[206].

Phillips et al.[162]applied a process for concentrating uranium from contaminated soils in which uranium is?rst extracted with bicarbonate and then the extracted uranium is precipitated with U(VI)-reducing microorganisms.Their results demonstrate that bicarbonate extraction of uranium from soil followed by microbial U(VI)reduction might be an effective mechanism for concentrating uranium from some contaminated soils.

Fig.11.Speciation of uranium depending on CO32?concentration(adapted upon [204–206]).

M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510493

Table8

Examples of different types of chelating compounds for uranil and corresponding chelats[55,201,202]

494M.Gavrilescu et al./Journal of Hazardous Materials163(2009)475–510 Table8(Continued)

Bench scale experiments described by Kulpa and Hughes[197] showed that a certain soil could be treated effectively using a0.2M sodium bicarbonate solution at a temperature of approximately 320?C and a retention time of1.5h and concluded that chemical treatment using carbonate extraction achieved removal ef?cien-cies of up to90%.A pilot plant designed to process2-ton batches of contaminated soil indicated that chemical extraction soil washing would result in contaminant removal ef?ciencies of approximately 82%and volume reductions of95%[197].

Based on these results,a soil washing facility of10ton/h pro-duction was designed and constructed,leading to important cost savings comparative to shipment and disposal procedure.A block diagram of this system is presented in Fig.12.This process which uses a relatively mild concentration of sodium carbonate to form a carbonate complex with uranium is approximately85–95%effec-tive depending on properties of the soil and source term of the uranium material contained in the soil.

The feasibility of the carbonate extraction process in a full-scale operation designed to leach uranium from contaminated soils using sodium carbonate/bicarbonate solution was also determined by several researchers[192,210,211].

3.4.1.2.Method using citric acid.Weak organic acids or their salts can be used as environmentally compatible compounds.Citrate is used as a complexing agent to mobilize sorbed and precipitated uranium in both in situ and ex situ extraction of soils and nuclear reactor components.Various researches revealed that citric acid is highly effective in uranium mobilization and the ef?ciency of extraction from contaminated soils increased with the acid concen-tration[202,213].However,care should be taken with the quantity of citric acid used in such systems,because additional quantities may result in uranium migration which contaminates groundwater.

Laboratory and bench-scale experiments were conducted by Kantar and Honeyman[212]to determine the ef?ciency of citric acid as an agent to mobilize and extract uranium from contami-nated soils.Some results indicated that citric acid is highly effective in removing uranium,and that the extraction ef?ciency increases with increasing citric acid concentration,especially under slightly acidic to alkaline conditions[212,214,215].

The enhanced U(VI)desorption in the presence of citrate may be explained through several processes,including the complexation of U(VI)with citrate and extraction of secondary coatings(e.g.,Fe), together with the liberation of Fe–citrate complexes into solution [212,215–217].In batch washing systems,the presence of10?3M citric acid enhances the extraction of uranium2.8times greater than water alone for the conditions of the experiment.Huang et al.[218]found a close correlation between the U and the Fe and Al concentrations in the soil solution after the addition of citric acid was found,explained by the dissolution of Fe and Al sesquioxides and hence release of U from soil material to the soil solution.For example,a removal ef?ciency of up to98%was achieved with10mL of10?3M citric acid in batch systems,whereas it is required150mL of0.1M citric acid to accomplish similar extraction ef?ciencies in column soil?ushing systems[212].

Citric acid(C6H8O7,H3Cit)has also been used to treat DU contaminated soil from various locations(OH,USA,Serbia)with removals ef?ciencies ranging from85to99%[125,163,217].The acid formed an aqueous complex with U(VI)under acidic conditions (below pH5.0)by the reaction(10)[219]:

UO22++Cit3?→UO2Cit?(10) An important advantage of U–citrate complexes for remediation accomplishments is their biodegradability.This may depend on the pH of the system,initial U:citrate molar ratios,contact time.For example,Huang et al.[218]and Gramss et al.[213]have found that, in solutions buffered at pH6–7,limited biodegradation of citrate occurred within10days with initial U:citrate molar ratios rang-ing from1:2to1:8,while over99%of the citrate is biodegraded

如何写先进个人事迹

如何写先进个人事迹篇一：如何写先进事迹材料如何写先进事迹材料一般有两种情况：一是先进个人，如先进工作者、优秀党员、劳动模范等；一是先进集体或先进单位，如先进党支部、先进车间或科室，抗洪抢险先进集体等。无论是先进个人还是先进集体，他们的先进事迹，内容各不相同，因此要整理材料，不可能固定一个模式。一般来说，可大体从以下方面进行整理。 (1)要拟定恰当的标题。先进事迹材料的标题，有两部分内容必不可少，一是要写明先进个人姓名和先进集体的名称，使人一眼便看出是哪个人或哪个集体、哪个单位的先进事迹。二是要概括标明先进事迹的主要内容或材料的用途。例如《王鬃同志端正党风的先进事迹》、《关于评选张鬃同志为全国新长征突击手的材料》、《关于评选鬃处党支部为省直机关先进党支部的材料》等。 (2)正文。正文的开头，要写明先进个人的简要情况，包括：姓名、性别、年龄、工作单位、职务、是否党团员等。此外，还要写明有关单位准备授予他(她)什么荣誉称号，或给予哪种形式的奖励。对先进集体、先进单位，要根据其先进事迹的主要内容，寥寥数语即应写明，不须用更多的文字。然后，要写先进人物或先进集体的主要事迹。这部分内容是全篇材料

的主体，要下功夫写好，关键是要写得既具体，又不繁琐；既概括，又不抽象；既生动形象，又很实在。总之，就是要写得很有说服力，让人一看便可得出够得上先进的结论。比如，写一位端正党风先进人物的事迹材料，就应当着重写这位同志在发扬党的优良传统和作风方面都有哪些突出的先进事迹，在同不正之风作斗争中有哪些突出的表现。又如，写一位搞改革的先进人物的事迹材料，就应当着力写这位同志是从哪些方面进行改革的，已经取得了哪些突出的成果，特别是改革前后的．经济效益或社会效益都有了哪些明显的变化。在写这些先进事迹时，无论是先进个人还是先进集体的，都应选取那些具有代表性的具体事实来说明。必要时还可运用一些数字，以增强先进事迹材料的说服力。为了使先进事迹的内容眉目清晰、更加条理化，在文字表述上还可分成若干自然段来写，特别是对那些涉及较多方面的先进事迹材料，采取这种写法尤为必要。如果将各方面内容材料都混在一起，是不易写明的。在分段写时，最好在每段之前根据内容标出小标题，或以明确的观点加以概括，使标题或观点与内容浑然一体。最后，是先进事迹材料的署名。一般说，整理先进个人和先进集体的材料，都是以本级组织或上级组织的名义；是代表组织意见的。因此，材料整理完后，应经有关领导同志审定，以相应一级组织正式署名上报。这类材料不宜以个人名义署名。写作典型经验材料-般包括以下几部分： (1)标题。有多种写法，通常是把典型经验高度集中地概括出来，一

脐带干细胞综述

脐带间充质干细胞的研究进展间充质干细胞（mesenchymal stem cells,MSC S ）是来源于发育早期中胚层的一类多能干细胞[1-5]，MSC S 由于它的自我更新和多项分化潜能，而具有巨大的治疗价值 ,日益受到关注。MSC S 有以下特点：(1)多向分化潜能，在适当的诱导条件下可分化为肌细胞[2]、成骨细胞[3、4]、脂肪细胞、神经细胞[9]、肝细胞[6]、心肌细胞[10]和表皮细胞[11, 12]；(2)通过分泌可溶性因子和转分化促进创面愈合；(3) 免疫调控功能，骨髓源（bone marrow ）MSC S 表达MHC-I类分子，不表达MHC-II 类分子，不表达CD80、CD86、CD40等协同刺激分子，体外抑制混合淋巴细胞反应，体内诱导免疫耐受[11, 15]，在预防和治疗移植物抗宿主病、诱导器官移植免疫耐受等领域有较好的应用前景；(4)连续传代培养和冷冻保存后仍具有多向分化潜能，可作为理想的种子细胞用于组织工程和细胞替代治疗。1974年Friedenstein [16] 首先证明了骨髓中存在MSC S ，以后的研究证明MSC S 不仅存在于骨髓中，也存在于其他一些组织与器官的间质中：如外周血[17]，脐血[5]，松质骨[1, 18]，脂肪组织[1]，滑膜[18]和脐带。在所有这些来源中，脐血(umbilical cord blood)和脐带(umbilical cord)是MSC S 最理想的来源，因为它们可以通过非侵入性手段容易获得，并且病毒污染的风险低，还可冷冻保存后行自体移植。然而，脐血MSC的培养成功率不高[19, 23-24]，Shetty 的研究认为只有6%，而脐带MSC的培养成功率可达100%[25]。另外从脐血中分离MSC S ，就浪费了其中的造血干/祖细胞(hematopoietic stem cells/hematopoietic progenitor cells,HSCs/HPCs) [26, 27]，因此，脐带MSC S (umbilical cord mesenchymal stem cells, UC-MSC S )就成为重要来源。一．概述人脐带约40 g, 它的长度约60–65 cm, 足月脐带的平均直径约1.5 cm[28, 29]。脐带被覆着鳞状上皮，叫脐带上皮，是单层或复层结构，这层上皮由羊膜延续过来[30, 31]。脐带的内部是两根动脉和一根静脉，血管之间是粘液样的结缔组织，叫做沃顿胶质，充当血管外膜的功能。脐带中无毛细血管和淋巴系统。沃顿胶质的网状系统是糖蛋白微纤维和胶原纤维。沃顿胶质中最多的葡萄糖胺聚糖是透明质酸，它是包绕在成纤维样细胞和胶原纤维周围的并维持脐带形状的水合凝胶，使脐带免受挤压。沃顿胶质的基质细胞是成纤维样细胞[32]，这种中间丝蛋白表达于间充质来源的细胞如成纤维细胞的，而不表达于平滑肌细胞。共表达波形蛋白和索蛋白提示这些细胞本质上肌纤维母细胞。脐带基质细胞也是一种具有多能干细胞特点的细胞，具有多项分化潜能，其形态和生物学特点与骨髓源性MSC S 相似[5, 20, 21, 38, 46]，但脐带MSC S 更原始，是介于成体干细胞和胚胎干细胞之间的一种干细胞，表达Oct-4, Sox-2和Nanog等多

脐带血造血干细胞库管理办法(试行)

脐带血造血干细胞库管理办法（试行）第一章总则第一条为合理利用我国脐带血造血干细胞资源，促进脐带血造血干细胞移植高新技术的发展，确保脐带血造血干细胞应用的安全性和有效性，特制定本管理办法。第二条脐带血造血干细胞库是指以人体造血干细胞移植为目的，具有采集、处理、保存和提供造血干细胞的能力，并具有相当研究实力的特殊血站。任何单位和个人不得以营利为目的进行脐带血采供活动。第三条本办法所指脐带血为与孕妇和新生儿血容量和血循环无关的，由新生儿脐带扎断后的远端所采集的胎盘血。第四条对脐带血造血干细胞库实行全国统一规划，统一布局，统一标准，统一规范和统一管理制度。第二章设置审批第五条国务院卫生行政部门根据我国人口分布、卫生资源、临床造血干细胞移植需要等实际情况，制订我国脐带血造血干细胞库设置的总体布局和发展规划。第六条脐带血造血干细胞库的设置必须经国务院卫生行政部门批准。第七条国务院卫生行政部门成立由有关方面专家组成的脐带血造血干细胞库专家委员会（以下简称专家委

员会），负责对脐带血造血干细胞库设置的申请、验收和考评提出论证意见。专家委员会负责制订脐带血造血干细胞库建设、操作、运行等技术标准。第八条脐带血造血干细胞库设置的申请者除符合国家规划和布局要求，具备设置一般血站基本条件之外，还需具备下列条件：（一）具有基本的血液学研究基础和造血干细胞研究能力；（二）具有符合储存不低于1 万份脐带血的高清洁度的空间和冷冻设备的设计规划；（三）具有血细胞生物学、HLA 配型、相关病原体检测、遗传学和冷冻生物学、专供脐带血处理等符合GMP、 GLP 标准的实验室、资料保存室；（四）具有流式细胞仪、程控冷冻仪、PCR 仪和细胞冷冻及相关检测及计算机网络管理等仪器设备；（五）具有独立开展实验血液学、免疫学、造血细胞培养、检测、HLA 配型、病原体检测、冷冻生物学、管理、质量控制和监测、仪器操作、资料保管和共享等方面的技术、管理和服务人员；（六）具有安全可靠的脐带血来源保证；（七）具备多渠道筹集建设资金运转经费的能力。第九条设置脐带血造血干细胞库应向所在地省级卫生行政部门提交设置可行性研究报告，内容包括：

个人先进事迹简介

个人先进事迹简介 01 在思想政治方面,xxxx同学积极向上,热爱祖国、热爱中国共产党,拥护中国共产党的领导.利用课余时间和党课机会认真学习政治理论,积极向党组织靠拢. 在学习上,xxxx同学认为只有把学习成绩确实提高才能为将来的实践打下扎实的基础,成为社会有用人才.学习努力、成绩优良. 在生活中,善于与人沟通,乐观向上,乐于助人.有健全的人格意识和良好的心理素质和从容、坦诚、乐观、快乐的生活态度,乐于帮助身边的同学,受到师生的好评. 02 xxx同学认真学习政治理论,积极上进,在校期间获得原院级三好生,和校级三好生,优秀团员称号,并获得三等奖学金. 在学习上遇到不理解的地方也常常向老师请教,还勇于向老师提出质疑.在完成自己学业的同时,能主动帮助其他同学解决学习上的难题,和其他同学共同探讨,共同进步. 在社会实践方面,xxxx同学参与了中国儿童文学精品“悦”读书系,插画绘制工作,xxxx同学在班中担任宣传委员,工作积极主动,认真负责,有较强的组织能力.能够在老师、班主任的指导下独立完成学院、班级布置的各项工作. 03 xxx同学在政治思想方面积极进取,严格要求自己.在学习方面刻苦努力,不断钻研,学习成绩优异,连续两年荣获国家励志奖学金；作

为一名学生干部,她总是充满激情的迎接并完成各项工作,荣获优秀团干部称号.在社会实践和志愿者活动中起到模范带头作用. 04 xxxx同学在思想方面,积极要求进步,为人诚实,尊敬师长.严格要求自己.在大一期间就积极参加了党课初、高级班的学习,拥护中国共产党的领导,并积极向党组织靠拢. 在工作上,作为班中的学习委员,对待工作兢兢业业、尽职尽责的完成班集体的各项工作任务.并在班级和系里能够起骨干带头作用.热心为同学服务,工作责任心强. 在学习上,学习目的明确、态度端正、刻苦努力,连续两学年在班级的综合测评排名中获得第1.并荣获院级二等奖学金、三好生、优秀班干部、优秀团员等奖项. 在社会实践方面,积极参加学校和班级组织的各项政治活动,并在志愿者活动中起到模范带头作用.积极锻炼身体.能够处理好学习与工作的关系,乐于助人,团结班中每一位同学,谦虚好学,受到师生的好评. 05 在思想方面,xxxx同学积极向上,热爱祖国、热爱中国共产党,拥护中国共产党的领导.作为一名共产党员时刻起到积极的带头作用,利用课余时间和党课机会认真学习政治理论. 在工作上,作为班中的团支部书记,xxxx同学积极策划组织各类团活动,具有良好的组织能力. 在学习上,xxxx同学学习努力、成绩优良、并热心帮助在学习上有困难的同学,连续两年获得二等奖学金. 在生活中,善于与人沟通,乐观向上,乐于助人.有健全的人格意识和良好的心理素质.

卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范(试行)

卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范(试行)》的通知【法规类别】采供血机构和血液管理【发文字号】卫办医政发[2009]189号【失效依据】国家卫生计生委办公厅关于印发造血干细胞移植技术管理规范(2017年版)等15个“限制临床应用”医疗技术管理规范和质量控制指标的通知【发布部门】卫生部(已撤销) 【发布日期】2009.11.13 【实施日期】2009.11.13 【时效性】失效【效力级别】部门规范性文件卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范（试行）》的通知（卫办医政发〔2009〕189号）各省、自治区、直辖市卫生厅局，新疆生产建设兵团卫生局：为贯彻落实《医疗技术临床应用管理办法》，做好脐带血造血干细胞治疗技术审核和临床应用管理，保障医疗质量和医疗安全，我部组织制定了《脐带血造血干细胞治疗技术管理规范（试行）》。现印发给你们，请遵照执行。二〇〇九年十一月十三日

脐带血造血干细胞治疗技术管理规范（试行）为规范脐带血造血干细胞治疗技术的临床应用，保证医疗质量和医疗安全，制定本规范。本规范为技术审核机构对医疗机构申请临床应用脐带血造血干细胞治疗技术进行技术审核的依据，是医疗机构及其医师开展脐带血造血干细胞治疗技术的最低要求。本治疗技术管理规范适用于脐带血造血干细胞移植技术。一、医疗机构基本要求（一）开展脐带血造血干细胞治疗技术的医疗机构应当与其功能、任务相适应，有合法脐带血造血干细胞来源。（二）三级综合医院、血液病医院或儿童医院，具有卫生行政部门核准登记的血液内科或儿科专业诊疗科目。 1.三级综合医院血液内科开展成人脐带血造血干细胞治疗技术的，还应当具备以下条件：（1）近3年内独立开展脐带血造血干细胞和（或）同种异基因造血干细胞移植15例以上。（2）有4张床位以上的百级层流病房，配备病人呼叫系统、心电监护仪、电动吸引器、供氧设施。（3）开展儿童脐带血造血干细胞治疗技术的，还应至少有1名具有副主任医师以上专业技术职务任职资格的儿科医师。 2.三级综合医院儿科开展儿童脐带血造血干细胞治疗技术的，还应当具备以下条件：

优秀党务工作者事迹简介范文

优秀党务工作者事迹简介范文优秀党务工作者事迹简介范文 ***，男，198*年**月出生，200*年加入党组织，现为***支部书记。从事党务工作以来，兢兢业业、恪尽职守、辛勤工作，出色地完成了各项任务，在思想上、政治上同党中央保持高度一致，在业务上不断进取，团结同事，在工作岗位上取得了一定成绩。一、严于律己，勤于学习作为一名党务工作者，平时十分注重知识的更新，不断加强党的理论知识的学习，坚持把学习摆在重要位置，学习领会和及时掌握党和国家的路线、方针、政策，特别是党的十九大精神，注重政治理论水平的提高，具有坚定的理论信念;坚持党的基本路线，坚决执行党的各项方针政策，自觉履行党员义务，正确行使党员权利。平时注重加强业务和管理知识的学习，并运用到工作中去，不断提升自身工作能力，具有开拓创新精神，在思想上、政治上和行动上时刻同党中央保持高度一致。二、求真务实，开拓进取在工作中任劳任怨，踏实肯干，坚持原则，认真做好学院的党务工作，按照党章的要求，严格发展党员的每一个步骤，认真细致的对待每一份材料。配合党总支书记做好学院的党建工作，完善党总支建设方面的文件、材料和工作制度、管理制度等。

三、生活朴素，乐于助人平时重视与同事间的关系，主动与同事打成一片，善于发现他人的难处，及时妥善地给予帮助。在其它同志遇到困难时，积极主动伸出援助之手，尽自己最大努力帮助有需要的人。养成了批评与自我批评的优良作风，时常反省自己的工作，学习和生活。不但能够真诚的指出同事的缺点，也能够正确的对待他人的批评和意见。面对误解，总是一笑而过，不会因为误解和批评而耿耿于怀，而是诚恳的接受，从而不断的提高自己。在生活上勤俭节朴，不铺张浪费。身为一名老党员，我感到责任重大，应该做出表率，挤出更多的时间来投入到**党总支的工作中，不找借口，不讲条件，不畏困难，将总支建设摆在更重要的位置，解开工作中的思想疙瘩，为攻坚克难铺平道路，以支部为纽带，像战友一样团结，像家庭一样维系，像亲人一样关怀，践行入党誓言。把握机遇，迎接挑战，不负初心。

主要事迹简介怎么写(2020年最新)

主要事迹简介怎么写概括?简要地反映?个单位(集体)或个?事迹的材料。简要事迹不?定很短，如果情况多的话，也有?千字的。简要事迹虽然“简要”，但切忌语?空洞，写得像?学?期末鉴定。 ?应当以事实来说话。简要事迹是对某单位或个?情况概括?简要地反映情况，?如有三个??很突出，就写三个??，只是写某???时，要把主要事迹突出出来。简要事迹?般来说，?少要包括两个??的内容。?是基本情况。简要事迹开头，往往要??段?字来表述?些基本情况。如写?个单位的简要事迹，应包括这个单位的?员、承担的任务以及?段时间以来取得的主要成绩。如写个?的简要事迹，应包括该同志的性别、出?年?、参加?作时间、籍贯、民族、?化程度以及何时起任现职和主要成绩。这样上级组织在看了材料的开头，就会对这个单位或个?有?个基本印象。?是主要特点。这是简要事迹的主体部分，最突出的事例有?个??就写成?块，并按照?定的逻辑关系进 ?排列，把同类的事例排在?起，?个??通常由?个?然段或?个?然段组成。写作时，特别要注意以下四点： 1.?第三?称。就是把所要写的对象，是集体的?“他们”来表述，是个?的称之为“他(她)”。 (她)”，单位可直接写名称，个?可写其姓名。为了避免连续出现?个“他们”或“他 2.掌握好时限。?论是单位或个?的简要事迹，都有?个时间跨度，既不要扯得太远，也不要故意混淆时间概念，把过去的事当成现在的事写。这个时间跨度多长，要根据实际情况 ?定。如上级要某个同志担任乡长以来的情况就写他任乡长以来的事迹;上级要该同志两年来的情况，就写两年来的事迹。当然，有时为了需要，也可适当地写?点超过这个时间的背景情况。 3.?点他?的语?。就是在写简要事迹时，可?些群众的语?或有关?员的语?，这样会给??种?动、真切的感觉，衬托出写作对象?较?的思想境界。在?他?语?时，可适当加?，但不能造假。 4.?事实说话。简要事迹的每?个??可分为多个层次，?个层次先??句话作为观点，再???两个突出的事例来说明。?事实说话时，要尽量把?个事例说完整，以给?留下深刻印象。

卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知

卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知发文机关：卫生部(已撤销) 发布日期： 2001.01.09 生效日期： 2001.02.01 时效性：现行有效文号：卫医发(2001)10号各省、自治区、直辖市卫生厅局：为贯彻实施《脐带血造血干细胞库管理办法（试行）》，保证脐带血临床使用的安全、有效，我部制定了《脐带血造血干细胞库设计管理规范（试行）》。现印发给你们，请遵照执行。附件：《脐带血造血干细胞库设置管理规范（试行）》二○○一年一月九日附件：脐带血造血干细胞库设置管理规范（试行）脐带血造血干细胞库的设置管理必须符合本规范的规定。一、机构设置（一）脐带血造血干细胞库（以下简称脐带血库）实行主任负责制。（二）部门设置脐带血库设置业务科室至少应涵盖以下功能：脐带血采运、处理、细胞培养、组织配型、微生物、深低温冻存及融化、脐带血档案资料及独立的质量管理部分。二、人员要求

（一）脐带血库主任应具有医学高级职称。脐带血库可设副主任，应具有临床医学或生物学中、高级职称。（二）各部门负责人员要求 1．负责脐带血采运的人员应具有医学中专以上学历，2年以上医护工作经验，经专业培训并考核合格者。 2．负责细胞培养、组织配型、微生物、深低温冻存及融化、质量保证的人员应具有医学或相关学科本科以上学历，4年以上专业工作经历，并具有丰富的相关专业技术经验和较高的业务指导水平。 3．负责档案资料的人员应具相关专业中专以上学历，具有计算机基础知识和一定的医学知识，熟悉脐带血库的生产全过程。 4．负责其它业务工作的人员应具有相关专业大学以上学历，熟悉相关业务，具有2年以上相关专业工作经验。（三）各部门工作人员任职条件 1．脐带血采集人员为经过严格专业培训的护士或助产士职称以上卫生专业技术人员并经考核合格者。 2．脐带血处理技术人员为医学、生物学专业大专以上学历，经培训并考核合格者。 3．脐带血冻存技术人员为大专以上学历、经培训并考核合格者。 4．脐带血库实验室技术人员为相关专业大专以上学历，经培训并考核合格者。三、建筑和设施（一）脐带血库建筑选址应保证周围无污染源。（二）脐带血库建筑设施应符合国家有关规定，总体结构与装修要符合抗震、消防、安全、合理、坚固的要求。（三）脐带血库要布局合理，建筑面积应达到至少能够储存一万份脐带血的空间；并具有脐带血处理洁净室、深低温冻存室、组织配型室、细菌检测室、病毒检测室、造血干/祖细胞检测室、流式细胞仪室、档案资料室、收/发血室、消毒室等专业房。（四）业务工作区域应与行政区域分开。

脐带血间充质干细胞的分离培养和鉴定

脐带血间充质干细胞的分离培养和鉴定【摘要】目的分离培养脐带血间充质干细胞并检测其生物学特性。方法在无菌条件下用密度梯度离心的方法获得脐血单个核细胞，接种含10%胎牛血清的DMEM培养基中。单个核细胞行贴壁培养后，进行细胞形态学观察，绘制细胞生长曲线，分析细胞周期，检测细胞表面抗原。结果采用Percoll(1.073 g/mL)分离的脐血间充质干细胞大小较为均匀，梭形或星形的成纤维细胞样细胞。细胞生长曲线测定表明接后第5天细胞进入指数增生期，至第9天后数量减少;流式细胞检测表明50%～70%细胞为CD29和CD45阳性。结论体外分离培养脐血间充质干细胞生长稳定，可作为组织工程的种子细胞。【关键词】脐血;间充质干细胞;细胞周期;免疫细胞化学 Abstract: Objective Isolation and cultivation of mesenchymal stem cells (MSCs) in human umbilical cord in vitro, and determine their biological properties. Methods The mononuclear cells were isolated by density gradient centrifugation from human umbilical cord blood in sterile condition, and cultured in DMEM medium containing 10% fetal bovine serum. After the adherent mononuclear cells were obtained, the shape of cells were observed by microscope, then the cell growth curve, the cell cycle and the cell surface antigens were obtained by immunocytochemistry and flow cytometry methods. Results MSCs obtained by Percoll (1.073 g/mL) were similar in size, spindle-shaped or star-shaped fibroblasts-liked cells. Cell growth curve analysis indicated that MSCs were in the exponential stage after 5d and in the stationary stages after 9d. Flow cytometry analysis showed that the CD29 and CD44 positive cells were about 50%～70%. Conclusions The human umbilical cord derived mesenchymal stem cells were grown stably in vitro and can be used as the seed-cells in tissue engineering. Key words:human umbilical cord blood; mesenchymal stem cells; cell cycle; immunocytochemistry 间充质干细胞(mesenchymal stem cells，MSCs)在一定条件下具有多向分化的潜能，是组织工程研究中重要的种子细胞来源。寻找来源丰富并不受伦理学制约的间充质干细胞成为近年来的研究热点[1]。脐血(umbilical cord blood, UCB)在胚胎娩出后，与胎盘一起存在的医疗废物。与骨髓相比，UCB来源更丰富，取材方便，具有肿瘤和微生物污染机会少等优点。有人认为脐血中也存在间充质干细胞(Umbilical cord blood-derived mesenchymal stem cells，UCB-MSCs)。如果从脐血中培养出MSCs，与胚胎干细胞相比，应用和研究则不受伦理的制约，蕴藏着巨大的临床应用价值[2,3]。本研究将探讨人UCB-MSCs体外培养的方法、细胞的生长曲线、增殖周期和细胞表面标志等方面，分析UCB-MSCs 作为间充质干细胞来源的可行性。

大学生先进事迹简介怎么写

大学生先进事迹简介怎么写苑xx，男，汉族，1990年07月22日出生，中国共青团团员，入党积极分子，现任xx学院电气优创0902班班长，担任xx学院09级总负责人、xx学院团委学生会科创部干事、xx学院文艺团主持部部长。步入大学生活一年以来，他思想积极，表现优秀，努力向党组织靠拢，学习刻苦，品学兼优，工作认真负责，脚踏实地，生活勤俭节约，乐于助人。一直坚持多方面发展，全面锻炼自我，注重综合能力、素质拓展能力的培养。再不懈的努力下获得了多项荣誉： ●获得09-10学年xx大学“百佳千优”(文化体育)一等奖学金和“百佳千优”(班级建设)二等奖学金; ●获得09-10学年xx大学“优秀学生干部”荣誉称号; ●2010年xx大学普通话知识竞赛中获得一等奖; ●2010年xx大学主持人大赛中获得一等奖，被评为金话筒; ●xx学院首届“大学生文明修身”活动周——再生比赛中获得一等奖; ●xx学院首届“大学生文明修身”活动周——演讲比赛中获得一等奖。一、刻苦钻研树学风作为班长，他在学习方面，将班级同学分成各个学习小组，布置每日学习任务，分组竞争，通过开展各项趣味学习活动，全面调动班级同学的积极性，如：排演英语戏剧、文学常识竞答、数学辅导小组等。他带领全班同学努力学习、勤奋刻苦，全班同学奖学金获得率达91%，四级通过率达66%。二、勤劳负责建班风

在日常班级工作中，他尽心尽力，通过网络组织建立班级博客，把班级的日常情况，班级比赛，特色主题班会等活动，及时上传到班级博客，以方便更多同学了解自己的班级，也把班级的魅力、特色，更全面、更具体的展现出来。在班级建设中，他带领全班同学参加学院组织的各项文体活动中也收获颇多： ●在xx学院首届“大学生文明修身”活动周中荣获第二名， ●xx学院首届乒乓球比赛中荣获第一名、精神文明奖， ●在xx学院“迎新杯”男子篮球赛中荣获第四名、最佳组织奖。除了参加学院组织的各项活动外，为了进一步丰富班级同学们的课余生活，他在班级内积极开展各式各样的课余活动： ●普通话知识趣味比赛，感受中华语言的魅力，复习语文文学常识，为南方同学打牢普通话基础，推广普通话知识。 ●“我的团队我的班”主题班会活动中，创办特色活动“情暖你我心”天使行动，亲切问候、照顾其他同学的生活、学习方面细节小事，即使在寒冷的冬天，也要让外省的同学感受到家一样的温暖。 ●“预览科技知识”科技宫之行，作为现代大学生，不能只顾书本知识，也要跟上时代，了解时代前沿最新科技。 ●感恩节“感谢我们身边的人”主题班会活动，在这个特殊的节日里，他带领同学们通过寄贺卡、送礼物等方式，来感谢老师辛勤的付出;每人写一封家书，寄给父母，感谢父母劳苦的抚育，把他们的感激之情，转化为实际行动来感化周围的人;印发感恩宣传单，发给行人，唤醒人们的感恩的心。三、热情关怀暖人心生活中，他更能发挥榜样力量，团结同学，增强班级凝聚力。时刻观察每一位同学的情绪状态，在心理上帮助同学。他待人热情诚恳，积极帮助生活中有困难的同学：得知班级同学生病高烧，病情严重，马上放下午饭，赶到同学寝室，背起重病同学到校医院进行

脐带血干细胞检测

脐带血干细胞检测对每份脐血干细胞进行下列检测： ①母体血样做梅毒、HIV和CMV等病原体检测，这一检测使脐血干细胞适合于其它家庭成员应用。如任何一种病原体测试阳性，需重复测定。 ②每份脐血干细胞样本同时检测确定没有微生物污染。 ③细胞活性检测、有核细胞数、CD34+细胞数、集落形成试验等。CD34是分子量115KD 的糖蛋白分子，使用特定单克隆抗体（抗-CD34）确定，脐血祖细胞的大部分，包括体外培养产生造血集落的细胞都包含在表达CD34抗原的细胞群中。 ④HLA组织配型、ABO血型。一、采血方式及其优点再生缘生物科技公司采用最严谨的封闭式血袋收集法，避免在收集脐带血液时可能遭受微生物污染的发生，且以最少之操作步骤，收集最大量之脐带血液方式，在产房内即可完成。二、脐带血处理与保存脐带血收集于血袋，经专人运送至再生缘生物科技公司之无菌细胞分离实验室后，由专业的技术人员于完全无菌的环境下，依标准操作程序将血液进行分离，收集具有细胞核的细胞，其中含有丰富的血液干细胞，经加入冷冻保护剂和适当品管检测后，并进行以最适合

血液干细胞的冷冻降温程序方式，进行细胞冷冻程序，达到避免细胞受到冷冻过程之伤害。完成后，冷冻细胞立刻保存于摄氏零下196度的液态氮槽中。所有操作程序记录和细胞保存相关数据，均由计算机条形码系统追踪确认，完全符合国际脐带血库之标准操作程序和品管要求。母亲血液之检测为确保所操作和保存的脐带血液细胞，符合国际血液操作规范，并提供客户最大的保障，对于产妇血液必须同时进行一些病毒传染病的检测，以确保没有下列病毒，如艾滋病毒(HIV)、C型肝炎病毒(HCV)、人类T细胞淋巴病毒(HTLV)和梅毒(syphilis)，同时对于B型肝炎病毒(HBV)和巨细胞病毒(CMV)加以侦测和纪录，作为将来可能应用脐带血细胞时之必要参考数据并符合卫生医疗之要求。脐带血细胞之品管对于所保存之脐带血细胞均进行多项操作流程监控和品管检测，如微生物污染检测、血液细胞浓度、细胞存活率、细胞活性测定等，每一步骤均有详细之纪录，在操作方法和使用仪器方面均定期进行验证和校验，以符合国际医疗标准。三、实验室、贮存处所介绍再生缘生物科技公司拥有符合美国联邦标准(FED-STD-209E)和中华民国优良药品制造标准（一区、二区、三区）的生物安全实验室和无菌操作设备，在专业的技术人员依标准操作程序下进行血液分离和保存步骤，保障客户珍贵样品和权益。分离后之细胞将依浓度分装入4-6个冷冻管，计算机降温冷冻完成后，即由食品工业发展研究所国家细胞库专业液态氮库房人员，将冷冻细胞分别存放于二个不同的脐带血细胞专属液态氮槽中保存，在安全机制上更有保障。液态氮库房拥有五吨的液态氮供应系统，每一液氮槽均有自动充填装置和异常警报系统，和每日值勤人员监控，确保冷冻细胞处于最佳的冷冻状态。四、安全管制措施脐带血液经快递送达无菌细胞分离实验室后，每一步骤均有专业技术人员操作和监督，并将所有分析数值详细填于具有条形码管制之分析表格和计算机数据表中，利用条形码和读码系统确认样品之专一性，避免人为失误，且便于追溯和数据品管。在冷冻细胞保存上

个人事迹简介

个人事迹简介我是来自计算机与与软件学院的学生，现在为青年志愿者协会的干事，在班级担任生活委员。在过去的一年里，我注重个人能力的培养积极向上，热心公益，服务群众，奉献社会，热忱的投身于青年支援者的行动中！一年时间虽短，但在这一年的时间里，作为一名志愿者，我确信我成长了很多，成熟了很多。“奉献、友爱、互助、进步”这是我们志愿者的精神，在献出爱心的同时，得到的是帮助他人的满足和幸福，得到的是无限的快乐与感动。路虽漫漫，吾将上下而求索！在以后的日子里，我会在志愿者事业上做的更好。在思想上，我积极进取,关心国家大事，并多次与同学们一起学习志愿者精神,希望我们会在新的世纪里继续努力,发扬我国青年的光传统,不懈奋斗,不断创造,奋勇前进,为实现中华民族的伟大复兴做出了更大的贡献。在学习上刻苦认真，抓紧时间，不仅学习好学科基础知识，更加学好专业课知识，在课堂上积极配合老师的教学，乐意帮助其它同学，有什么好的学习资料，学习心得也与他们交流，希望大家能共同进步。在上一个年度总成绩在班级排名第四，综合考评在班级排名第二。在工作中，我认真负责，出色的完成老师、同学交给的各项任务，所以班级人际关系良好。

此外参加了学院组织的活动，并踊跃地参加，发挥自己的特长，为班级争得荣誉。例如：参加校举办的大合唱比赛并获得良好成绩；参加了计算机与软件学院党校学习并顺利结业；此外,参加了计算机与软件进行的“计算机机房义务打扫与系统维护”的活动。在这些活动中体验到了大学生生活的乐趣。现将多次参与各项志愿活动汇报如下：2013年10月26日，参加计算机与软件学院团总支实践部、计算机与软件学院青年志愿者协会组织“志愿者在五福家园的健身公园开展义务家教招新活动”；2013年11月7日，参加组成计算机与软件学院运动员方阵在田径场参加学院举办的学校运动会；2013年12月5日，参与学校学院组织的”一二．五“大合唱比赛；2014年3月12日，参加由宿舍站长组织义务植树并参与植树活动；2014年3月23日，在计算机与软件学院团总支书记茅老师的带领下，民俗文化传承协会、计算机与软件学院青年志愿者协会以及学生会的同学们参观了“计算机软件学院的文化素质教育共建基地--南京市民俗博物馆”的活动；2014年3月26日，参加有宿舍站长组织的“清扫宿舍公寓周围死角垃圾”的活动；2014年4月5日，参加由校青年志愿者协会、校实践部组织的“南京市雨花台扫墓”活动，2014年4月9日，作为班级代表参加计算机软件学院组织部组织的“计算机应用office操作大赛”的活动。在参与各项志愿活动的同时，我的学习、工作、生活能力得到了提高和认可，丰富生活体验，提供学习的机会，提供学习的机会。

个人事迹简介10篇(优秀版)

《个人事迹简介》个人事迹简介（一）：李维波，男，中共党员，自2003年应聘农电工以来，他就把自己的一切奉献给了他热爱的电力事业。在多年的工作中爱岗敬业，勤勤恳恳，任劳任怨。2003年至2007年先后担任过xx供电所线损管理员、用电检查管理员、两率管理员、线路工作负责人;2007年调到xx供电所任用电检查管理员、客户经理;2009年5月调到xx供电所任营销员兼用电检查管理员。刚踏入电力工作的时候，他还是个电力行业的门外汉，可他深深的明白：知识改变思想!思想改变行动!行动决定命运这句话，明白在当今学习的社会里，对于电力更就应不断的吸取新的知识，更新新的观念，以满足时代对于电力的更高的要求。正是这样他透过自己的努力学习，一步步的从门外汉变成了此刻的技术骨干。一、加强政治学习，提高理论思想水平多年以来，他在工作中始终坚持学习邓小平理论和三个代表重要思想。他深知：一个人只有有了与时俱进的思想做指导，人的认识才会提高，思想才能净化，行为也才能与时代同步，与社会同步，与发展同步，也才能成为社会发展的推动者、有作为者，正因为如此，他严格要求自己，认真学习思想理论方面的知识，抓紧一切时间学习，认真听，做好笔记，写好心得，并且用三个代表思想来约束自己，不断提高自身的修养，从而真正实践党的全心全意为人民服务的宗旨。二、加强专业知识的学习，提高专业技术在当今信息化的时代，科学技术飞速发展，尤其在电力行业这个技术密集型企业中，学习显得尤为重要。从踏进电力企业的大门开始，他就自觉学习专业知识，以书本为老师，阅读各方面的相关书籍，不断丰富自己的理论基础;以老同志为师傅，细心观察他们的实际操作，不断丰富自己的实践经验;以实践为老师，从中加深对知识的理解和领会。从2003年开始，学会了计算机普通操作，掌握了电力安全方面相关知识、电工基础知识、供电营业规则，参加局每年安规考试多次得到全局前十名，2005年农电体制改革考试应知和应会总分全局第5名。三、发扬三千精神，做好优质服务 2007年，xx所因滩坑移民影响，电费回收率难以上升，应对电费回收的复杂严峻形势，

主要事迹简介怎么写

员工主要事迹写法：ｘｘ，一个普通的名字。一个平凡的身影，经常出现在酒店的各个区域巡视。他是保安部副主管。ｘｘ，自20ｘｘ年x月份进入酒店工作以来，一直表现出色，爱岗敬业，努力学习业务知识，也因此由一名普通保安员逐步成长为酒店一名管理人员，在20ｘｘ年x月正式接手保安部副主管一职。同年6月，参加宁波消防安全管理员的培训，并拿到了相应的资格证书。作为酒店一名基层管理者，他处处起到了模范带头的作用，他的工作态度会影响整个团队，正所谓：火车跑得快，全靠车头带。在日常工作中他不怕困难，勇于承担责任，用在工作上，就是那份执着、坚定、信念。每当这时，他总是憨厚的笑笑：“还是领导有方，我只是一个执行者罢了”！ 20ｘｘ年x月份，根据国家气象局预报的台风预测消息，第9号强台风“梅花”正向本地移动，可能在6日夜间在浙江省中北部沿海登陆，或紧擦宁波市沿海北上，但不管哪种路线都将对宁波造成严重影响。我酒店在林总经理的号召下，立即由工程部张经理带领工程保安部及各部门相关人员迅速成立临时抗台小组。ｘｘ也同时参加了前期各项准备工作，并同相关人员一同在酒店蹲守两个日夜，直至“梅花”绕道离开。他还开玩笑说：“这个日子很特别，七夕情人节碰上了梅超风”。

20ｘｘ年，对于酒店保安部来说，是较为艰辛的一年，由于市场原因，使得保安部人力处于紧张状态，即使如此，他还是较为圆满的完成了部门的各项培训及其它各项工作，并在ｘｘ月份对酒店全员进行了为期三天的消防知识培训，用自己所学到的知识来跟大家一起分享。同月底，在酒店各层领导的组织与鼓励下圆满的完成了消防模拟演习，事后他说：“大家都比我做的好，我还要努力加强学习啊”。 20ｘｘ年底，酒店餐饮客情非常好，餐饮部自身人员不能满足服务需求，需要其他部门帮工跑菜，这个问题也就落在了工程保安部的肩上。每天在厨房都能看到那一身保安制服的跑菜员，不用问，那肯定是ｘｘ。仅x月份，他在做好自己本职工作的同时，利用非当班时间帮工累计56小时。当然也有其他部门的帮工人员，他们都是优秀的，正是有这些非常优秀的员工，使得酒店营业部门顺利完成了各项任务。每当这时，他又会说：“我虽然是过来帮忙的，但我要把它当成自己的本职工作来做”。 20ｘｘ年底，临近春节，好多员工都想回家过年，保安部员工也不例外，但人员紧张怎么办呢，他又给大家做思想工作，同时分开安排人员回家的假期，以保证春节期间的正常排班，保障酒店的正常运行。但谁能知道他在酒店工作三年多了，每年的春节都是在酒店过的，每年的中秋节也都是在酒店过的，难道他不想在佳节时与家人团聚吗?每当这时，他又说：“人员紧张，名额有限，让给他们。呵呵，再说，我是以店为家”，也许这时，他的笑容里带有一丝让人难以察觉的苦涩！

Characterization and remediation of soils contaminated with uranium

如何写先进个人事迹

脐带干细胞综述

最新小学生个人读书事迹简介怎么写800字

脐带血造血干细胞库管理办法(试行)

个人先进事迹简介

卫生部办公厅关于印发《脐带血造血干细胞治疗技术管理规范(试行)

优秀党务工作者事迹简介范文

主要事迹简介怎么写(2020年最新)

卫生部关于印发《脐带血造血干细胞库设置管理规范(试行)》的通知

最新树立榜样的个人事迹简介怎么写800字

脐带血间充质干细胞的分离培养和鉴定

大学生先进事迹简介怎么写

脐带血干细胞检测

个人事迹简介

个人事迹简介10篇(优秀版)

主要事迹简介怎么写

相关文档

最新文档