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In situ stabilization of cadmium-, lead-, and zinc-contaminated soil using various amendments

In situ stabilization of cadmium-, lead-, and zinc-contaminated soil using various amendments
In situ stabilization of cadmium-, lead-, and zinc-contaminated soil using various amendments

In situ stabilization of cadmium-,lead-,and zinc-contaminated soil using various amendments

Sang-Hwan Lee a,*,Jin-Soo Lee a ,Youn Jeong Choi b ,Jeong-Gyu Kim b

a Technology Research Center,Mine Reclamation Corporation,Seoul 110-727,Republic of Korea

b

Division of Environmental Science and Ecological Engineering,Korea University,Seoul 136-713,Republic of Korea

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

Received 1April 2009

Received in revised form 30August 2009Accepted 31August 2009

Available online 27September 2009Keywords:Amendments Bioavailability Heavy metals

In situ remediation Stabilization

a b s t r a c t

Chemical stabilization is an in situ remediation method that uses inexpensive amendments to reduce contaminant availability in polluted soil.We tested the effects of several amendments (limestone,red-mud,and furnace slag)on the extractability of heavy metals,microbial activities,phytoavailability of soil metals (assessed using lettuce,Lactuca sativa L.),and availability of heavy metals in ingested soil to the human gastrointestinal system (assessed using the physiologically based extraction test).The application of soil amendments signi?cantly decreased the amount of soluble and extractable heavy metals in the soil (p <0.05).The decreased extractable metal content of soil was accompanied by increased microbial activity and decreased plant uptake of heavy metals.Soil microbial activities (soil respiration,urease,and dehydrogenase activity)signi?cantly increased in limestone and red-mud-amended soils.Red-mud was the most effective treatment in decreasing heavy-metal concentrations in https://www.sodocs.net/doc/1713756845.html,pared to non-amended control soil,lettuce uptake of Cd,Pb,and Zn was reduced 86%,58%,and 73%,respectively,by the addition of red-mud.

ó2009Elsevier Ltd.All rights reserved.

1.Introduction

Heavy-metal contamination of soil is a worldwide problem.Accumulations of heavy metal in soil adversely affect food quality,soil health,and the environment.In response,the development of technologies to remediate heavy-metals contaminated soils has been ongoing (Gray et al.,2006).

Soil-remediation technologies based on the excavation,trans-port,and land?lling of contaminated soils and wastes are highly effective at lowering risk,but may be too expensive to implement (Basta and McGowen,2004).Moreover,engineered technologies are often environmentally invasive and do not permit a natural reshaping of the environment (Lombi et al.,2002).Innovative low-cost,low-input technologies are needed for soil remediation and community acceptance.One promising technology is the in situ stabilization of heavy metals in soils by the addition of var-ious amendments (Oste et al.,2002;Basta and McGowen,2004).Compared with other remediation techniques,in situ chemical sta-bilization is less expensive and may provide a long-term remedia-tion solution through the formation of low-solubility minerals or precipitates.

In situ stabilization of metals is based on the reduction of metal mobility and availability,either by precipitation or increased

sorption.The application of certain soil amendments may decrease the solubility of contaminants and thus reduce the detrimental ef-fects of heavy metals on environmental receptors,such as microor-ganisms,plants,animals,water bodies,and humans (Lombi et al.,2002).

Numerous amendments have been proposed and tested for in situ stabilization of heavy metals in soils,including agricultural products,such as lime (Geebelen et al.,2003),phosphate (Basta and McGowen,2004),and organic matter (Brown et al.,2004),as well as various industrial products,such as zeolites (Oste et al.,2002)and red-mud (Lombi et al.,2002;Gray et al.,2006).Their use also achieves reduction of waste disposal through revaloriza-tion of industrial wastes into industrial co-products.One example is the use of red-mud and furnace slag.Red-mud is produced in large quantities during the extraction of alumina from bauxite,annually 0.2Mt of red-mud are produced in Korea.Huge amounts of furnace slag are also produced;0.15t t à1steel of slags are produced.These materials has been investigated in relation to hea-vy-metal ?xation in soil.Lombi et al.(2002)reported that red-mud amendment shifted metals from the exchangeable to the Fe-oxide fraction,and decreased acid extractability of metals.Chen et al.(2000)reported that Cd uptake by wetland rice was signi?cantly reduced by furnace-slag treatment.

Ef?cient in situ stabilization of heavy metals may bene?t soil functionality by reducing labile element pools of heavy metals,but the dynamics and restoration of soil-based ecosystem

0045-6535/$-see front matter ó2009Elsevier Ltd.All rights reserved.doi:10.1016/j.chemosphere.2009.08.056

*Corresponding author.Tel.:+820237026764;fax:+820237026749.E-mail address:soillsf@mireco.or.kr (S.-H.Lee).Chemosphere 77(2009)

1069–1075

Contents lists available at ScienceDirect

Chemosphere

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 /c he m o s p h e r

e

processes have received little systematic attention.The recovery of derelict soils should be assessed not only by soil chemical charac-teristics determined by conventional analytical tests and extrac-tion procedures,but also by assays that measure the restoration of soil habitat function(Brown et al.,2005).In fact,chemical data alone are not suf?cient to evaluate the toxic effects of pollutants and characterize contaminated environments,as they do not con-sider the effects of chemical compounds on organisms or the inter-actions among contaminants,the soil matrix,and biota(Brown et al.,2005;Leitgib et al.,2007).The use of biological endpoints to help de?ne acceptable cleanup standards is important(Dorn and Salanitro,2000).The microbiological and biochemical status of a soil has often been proposed as a sensitive early indicator of soil ecological stress in restoration processes(Pérez-de-Mora et al.,2005;Hinojosa et al.,2008)and may indicate the potential of the soil to sustain microbiological activity,which can be used to evaluate the effectiveness of a soil remediation process(Pérez-de-Mora et al.,2005;Tejada et al.,2006).

We assessed the ability of several industrial byproducts(lime-stone,red-mud,and furnace slag)to reduce the availability of hea-vy metals in soil and evaluated the response of biological indicators to the soil amendments.These indicators included soil microbial activity(soil respiration,microbial biomass,and soil en-zyme activity),plant growth,and plant metals uptake.

2.Materials and methods

2.1.Characterization of soil and amendments

Soil was collected from agricultural land adjacent to the aban-doned Seosung gold mine in Chungnam Province,Korea (36°5300.300N,126°24059.800E).We determined the physico-chemi-cal properties of the soil(<2mm)and amendments(Table1). The amendments,limestone,red-mud,and furnace slag were col-lected from limestone mine,alumina smelters,and steel works, respectively.Soil textural analysis was performed using the pipet-ting method of Gee and Bauder,1986.Soil pH and electrical con-ductivity(EC)were determined using1:5soil/H2O(Thomas, 1996).Total C and Kjeldahl nitrogen were determined by the Turin (Nelson and Sommers,1996)and Kjeldahl method(Mremner, 1996),respectively.Cation exchange capacity was determined using the ammonium-saturation and distillation method(Sumner and Miller,1996).Total concentrations of metals in the soil and amendments were estimated using United States Environmental Protection Agency Method3050B(USEPA,1986).

Table1shows the main physico-chemical properties of both the soil and amendments used in this investigation.

2.2.Experimental set-up

Amendments(limestone,red-mud,and furnace slag)were ap-plied to soils at2%and5%w/w ratio.All amendments used in this experiment were reduced to a particle size of<2mm.Non-amended soil was used as the control.The amendments were thor-oughly mixed with the soils to obtain homogeneity,and were then equilibrated for40d,during which soil moisture was maintained, and the soils were thoroughly mixed at weekly intervals.

2.3.Contaminant extractability and bioavailability

The effect of each amendment on contaminant extractability was evaluated using deionized water(DW)and0.1M Ca(NO3)2. DW(pH7)extraction was conducted using a modi?cation of the Scott-Fordsmand et al.(2000)procedure:3g soil were added to 30mL DW in40-mL polypropylene centrifuge tubes,which were then shaken for2h on a wrist-action shaker,centrifuged for 20min at5100g,and then?ltered through Whatman(Maidstone, UK)GF/F0.7-l m borosilicate glass?lters.Extraction with0.1M Ca(NO3)2solution was performed according to the procedure of Conder et al.(2001)to measure Ca(NO3)2-extractable metals:1g soil was combined with0.1M Ca(NO3)2,mixed in a shaker,centri-fuged for20min at5100g,and then?ltered through Whatman GF/ F0.7-l m borosilicate glass?lters.

The availability to the human gastrointestinal(GI)system of Pb in ingested soil was estimated using the modi?ed physiologically based extraction test(PBET)procedure described by Geebelen et al.(2003):0.35g soil was shaken(30rpm)with synthetic gastric solution(0.4M glycine;pH2.2)for1h at37°C,and then?ltered through Whatman GF/F0.7-l m borosilicate glass?lters.

Changes in the metal fraction were determined using the proce-dure of Tessier et al.(1979),which separates heavy metals into?ve operationally de?ned fractions:extractable with1M NH4OAc at pH7(exchangeable);extractable with1M NH4OAc at pH5(car-bonate-bound);extractable with hydroxylamine(associated mainly with Fe–Mn oxides);extractable with H2O2in1M HNO3 (strongly complexed with organic matter);and HClO4-and HF-extractable(residual).

2.4.Microbial activities

Immediately following40d aging,soils were subsampled to determine enzyme activity and soil microbial biomass,which were used as microbial endpoints.Soil subsamples were kept moist at <4°C.Before analyses,samples were sifted through a2-mm sieve, and their water content was determined to express microbial activity on a dry-matter basis.Microbial biomass was determined by measuring substrate-induced respiration:soil was amended with glucose(4mg gà1soil)and incubated for4h at20°C.CO2 produced during the test was absorbed in NaOH and quanti?ed by titration with0.05M hydrochloric acid.Basal soil respiration was measured by measuring the CO2production at25°C without the addition of glucose,in which?eld-moisture soil was incubated in a closed vessel at25°C.The CO2produced was absorbed in 0.05M sodium hydroxide and quanti?ed by titration with0.l M hydrochloric acid.Before the titration,barium chloride was added to precipitate the absorbed CO2as barium carbonate.

Soil urease activity was measured using the method of Kandeler (1995),and phosphatase activity was determined using p-nitro-phenyl phosphate disodium as a substrate(Tabatabai and Bremner,

Table1

Soil physico-chemical properties and total metal concentrations of the soils and

amendments used in this experiment a.

Parameter Soil Limestone Red-mud Furnace slag

pH b 5.78.9111.3210.57

Clay c15.2–g––

Silt26.8–––

Sand58.1–––

CEC d11.8–––

Total carbon(%) 2.6–––

Total nitrogen(%)0.02–––

Cd(mg kgà1)e10.7 1.2 2.1 1.7

Cu(mg kgà1)47.123.3 6.810.7

Pb(mg kgà1)125220.978.260.6

Zn(mg kgà1)53052160.641.6

Fe oxides f– 2.5223.118.6

Al oxides– 2.4 5.3 3.8

a Mean values and standard deviations of three replicates.

b Soil pH measured at the ratio of soil to H

2

O as1:5(mass:volume).

c Particle size(%)was analyze

d by pipetting method.

d Cation exchang

e capacity(cmol kgà1).

e Aqua regia extractable metal concentration.

f Fe,Al oxides were analyzed by citrate and Na-dithionite extraction method.

g‘‘–”means not determined.

1070S.-H.Lee et al./Chemosphere77(2009)1069–1075

1969).Dehydrogenase activity was determined by the reduction of 2,3,5-triphenyltetrazolium chloride to triphenyl formazan(Casida et al.,1964).

2.5.Phytoavailability

To examine the effect of the addition of amendments on the phytoavailability of contaminants,lettuce(Lactuca sativa L.)was grown in plastic pots(1kg capacity,15-cm diameter,25-cm height)?lled with contaminated soils,prepared as described above.Lettuce seeds were initially sown in peat-based horticul-tural compost.2week after germination,the seedlings were trans-planted into contaminated soils(5seedlings/pot,3pots per treatment).The trials were conducted under controlled green-house conditions(temperature15–25°C,relative humidity60–70%)with daily watering.After45d,the lettuce was harvested, rinsed with DW,and dried at80°C for48h.Lettuce shoot samples were digested in hot nitric acid,and the resultant solutions were ?ltered.A certi?ed plant material(i.e.NIST1570a)was used to en-sure the quality of plant digestion analyses.The average recoveries were93%,107%,and98%for Cd,Pb,and Zn,respectively.

2.6.Quality control

All chemicals were of analytical grade or better.Centrifuges were acid-washed(5%HNO3)before each use,and disposable lab-ware was used for all other analyses.Heavy-metals analyses were conducted using inductively coupled plasma optical emission spectrometry;blanks were run for background correction and other error sources.Multi-element standards were run every20 samples,with recovery within100±10%.The detection limit of Cd,Pb,and Zn was0.001,0.001,and0.003mg Là1,respectively.

2.7.Statistical analyses

All values obtained from soil chemical and biological analyses were reported as the means of three replicates.The data were checked for homogeneity of variance and normality(Kolmogo-rov–Smirnov test)and,when possible,subjected to one-way ANO-VA.For signi?cant differences(p<0.05),a post hoc Tukey honestly signi?cant difference test was used to further elucidate differences among means(p<0.05).Pearson correlation coef?cients were cal-culated between soil metal contents and microbial activity and plant metal contents.Statistical analyses were conducted using SPSS11.5for Windows.

3.Results

3.1.Soil pH and EC

After amendments were applied,both pH and EC increased sig-ni?cantly(p<0.05;Table2).Soil pH increased from 5.74to approximately7.97,8.94,and 6.28in5%limestone-,5%red-mud-and5%furnace-slag-amended soils,respectively.Soil EC in-creased from164to350,694,and200l S cmà1in the5%of lime-stone,red-mud,and furnace-slag treatment,respectively.

3.2.Contaminant extractability and bioavailability

The application of amendments had no signi?cant effect (p>0.05)on total Cd,Pb,and Zn concentrations in soil(Table2). We determined extractable metal concentrations and bioavailable soil Pb(Table2).The DW and Ca(NO3)2extracts used as surrogate measures of metal availability were non-aggressive extracts devel-oped to measure readily labile metals in soils.

The amounts of DW-extractable metals were signi?cantly re-duced(p<0.05)by the addition of amendments,with the excep-tion of Pb in red-mud-amended soils.Before the application of amendments,the soil contained,on average,1.19%,0.02%,and 0.32%of total content of Cd,Pb,and Zn,respectively,in DW-extractable forms.The most noticeable reduction in DW-extract-able metals was observed in soil with a5%limestone amendment, in which DW-extractable Cd,Pb,and Zn were reduced to0.02%, 0.003%,and0.01%of total content,respectively.However,red-mud resulted in a signi?cant increase in DW-extractable Pb con-centrations;compared to non-amended soil,red-mud-amended soil had a tenfold increase in DW-extractable Pb.

The application of amendments also signi?cantly decreased Ca(NO3)2-extractable metal concentrations,with red-mud being the most https://www.sodocs.net/doc/1713756845.html,pared to the control soil,a5%red-mud addition reduced Ca(NO3)2-extractable Cd,Pb,and Zn by88%, 88%,and99%,respectively.

Bioaccessible soil Pb was determined using the PBET method (Table2).In the control soil,40%of Pb,on average,was bioaccessi-ble.However,unlike soluble and extractable metal concentrations, the application of soil amendments did not signi?cantly affect the proportion of bioaccessible Pb(p>0.05),which was32–41%,on average,of the total soil Pb content across all the amended soils. PBET Pb decreased signi?cantly only in the2%red-mud treatment, which resulted in32%of total Pb in a bioaccessible form.

Sequential extraction was used to investigate the distribution of metals among different soil pools(Fig.1).Initially,Cd existed in a more bioavailable and mobile form than the other metals,with 18.5%of total Cd exchangeable,whereas Pb and Zn were mainly in the residual fraction form,with very low exchangeable fractions (2.0%and4.4%of total content,respectively).

The application of soil amendments shifted metal distributions from the exchangeable to the carbonate and Fe–Mn oxide fractions. The shift from the exchangeable to the carbonate fraction was sig-ni?cant in the limestone treatment,and the shift to Fe–Mn oxide fractions was most notable in the red-mud treatment.

We investigated the effect of lowering the soil pH(by adding acid)on the extraction of metals(Fig.2).The amendments had dif-ferent effects on the reacidi?cation of soil and remobilization of

Table2

pH,electrical conductivity(EC),total and extractable heavy metals(mg kgà1)of the soils with different amendment addition.

Treatment pH EC(l S cmà1)Total DW-extractable Ca(NO3)2PBET

Cd Pb Zn Cd Pb Zn Cd Pb Zn

Control 5.74e164g10.81a1295a545a0.13a0.31c 1.74a 3.94a 5.32a31.22a40a LS2%7.91b338d9.89a1211a514a0.00d0.04c0.04d0.13e0.07d0.17d39ab LS5%7.97b354c9.52a1212a505a0.00d0.03d0.04d0.10e0.03d0.11d36bc RM2%7.90b435b9.66a1284a529a0.00d 1.25b 1.09c0.52d0.46d 1.39d32d RM5%8.94a694a9.68a1220a496a0.06c 3.67a 1.27bc0.07e0.12d0.19d33c FS2% 5.93d185f10.09a1261a529a0.09b0.24cc 1.48ab 3.29b 3.54b24.25b41a FS5% 6.28c200e9.32a1280a499a0.08bc0.19c0.95c 2.33c 1.99c14.08c41a

Means(n=3)followed by same letter within a row are not signi?cantly different(p>0.05).

LS,Limestone;RM,Red-mud,FS,Furnace slag.

S.-H.Lee et al./Chemosphere77(2009)1069–10751071

metals.In non-amended soil,soil pH decreased drastically with the addition of acid and the extractability of metals increased signi?-cantly.In soils amended with furnace slag(2%and5%),the change in the solubility of Cd,Pb,and Zn in response to pH change was similar to that of non-amended soil,whereas the soil pH change was small and the extractability of metals was signi?cantly re-duced in limestone-and red-mud-amended soils.

3.3.Soil microbial activity

Compared to non-amended soil,signi?cantly more CO2was evolved,and dehydrogenase and urease activity were higher,in limestone-and red-mud-amended soils(p<0.05;Table3),whereas no signi?cant differences in microbial biomass(evaluated by substrate-induced respiration)or alkaline phosphatase activity were observed among amendments or in non-amended soil.

Table4shows the Pearson’s correlation coef?cients between microbial activities and heavy-metals concentrations.Signi?cant negative correlations were observed between heavy-metal con-tents and soil microbial activities(respiration,dehydrogenase, and urease activity).The correlation coef?cients were signi?cantly higher between soil microbial activities and Ca(NO3)2-extractable metal contents than between soil microbial activities and total me-tal content.

3.4.Plants

With the exception of the red-mud treatment,lettuce shoot yields did not differ signi?cantly(p>0.05)among treatments.

; Fe, Mn-oxide bounded ; Organic matter bounded

1072S.-H.Lee et al./Chemosphere77(2009)1069–1075

Although some treatments appeared to increase lettuce biomass relative to the control,the differences were not statistically signif-icant.The2%red-mud treatment produced a signi?cantly (p<0.05)higher shoot yield than did the other https://www.sodocs.net/doc/1713756845.html,-pared to the non-amended soil,the2%red-mud-amended soil pro-duced80%more shoot biomass(Fig.3).

Compared to the control soil,the limestone and red-mud appli-cations signi?cantly(p<0.05)decreased the concentrations of all heavy metals except Pb in lettuce(Fig.3).Compared to non-amended soil,13–29%of Cd and27–38%of Zn were translocated to lettuce shoots in the limestone-and red-mud-amended soils. Only the limestone treatment signi?cantly reduced Pb uptake. Compared to the control soil,51%and40%of Pb translocated in the2%limestone-and5%limestone-amended soils,respectively, whereas neither5%red-mud nor furnace-slag treatments reduced Pb uptake signi?cantly(p>0.05).

Table4shows the correlation coef?cients between soil metal contents and heavy-metal concentrations in lettuce shoots.The correlation coef?cients were signi?cantly higher between and extractable metal contents than between shoot metal concentra-tions and total metal content.

4.Discussion

The application of amendments that can immobilize heavy met-als in situ may provide a cost-effective and sustainable solution for the remediation of contaminated soil(Mench et al.,2000;Oste et al.,2002).In this study,we compared the ability of several types of amendments to reduce heavy-metals availability.

The total concentrations of Cd,Pb,and Zn in soil did not change signi?cantly when amendments were added(Table2).Consequently,the heavy-metals load of mine soil,for example, would not be affected by these amendments.Although the amendments had no effect on total metals concentrations,they signi?cantly decreased the soluble and extractable fractions of heavy metals in soil.

The signi?cant decrease of DW-and Ca(NO3)2-extractable metal concentrations,which represent heavy metals that are sorbed onto the soil solid phase,indicates that these metals can be desorbed into solution to replenish the soluble metal pool(McLaughlin et al.,2000).The decreased concentrations of soluble and extract-able heavy metals in the amended soils can be attributed in part to a signi?cant increase in soil pH(Table2)caused by the alkaline nature of the amendments.Ca(NO3)2-extractable heavy-metal con-tents were signi?cant negatively correlated with soil pH(r2value was0.903,0.800,and0.858for Cd,Pb,and Zn,respectively).

Unlike the other metals,DW-extractable Pb concentrations in-creased with red-mud addition(Table2),which may be attribut-able to dissolved organic carbon(DOC).DOC compounds likely decreased the sorption of Pb onto soil surfaces,either by compet-ing for free metals and forming soluble organo-complexes or by being preferentially sorbed onto surfaces over competing metals (Giusquiani et al.,1998).Gray et al.(2006)reported a signi?cantly higher DOC amount in red-mud-amended soil and the inhibition of Pb sorption(stabilization)by DOC.

Unlike DW-and Ca(NO3)2-extractable metal contents,the ef-fects of amendments on bioavailable Pb,determined using the PBET,were minimal(Table2),which may be attributed to the dif-ference in the extractant pH.The acidic(pH2.2)extraction solution of the PBET is more aggressive at dissolving Pb than is a neutral solution(pH7.0;DW or Ca(NO3)2).Thus,Pb is easily desorbed and solubilized by the low pH of the GI tract(Geebelen et al.,2003).

Table3

Soil microbial activities in soil with different amendment addition.

Treatments Microbial biomass

(mg CO2àC hà1100gà1soil)Respiration

(mg CO2100gà1soil)

Soil enzyme

DHA URE PME

(mg TPF kgà1soil)(mg NHt

4

kgà1soil)(mg NP kgà1soil)

Control228c9.6e69d 1.8d973a

LS2%247c24b99c 3.1b896ab LS5%238c22bc92c 2.8bc900ab

RM2%368bab14de138a 2.6c971a

RM5%391a33a119ab 3.5a989a

FS2%294bc16cd71d 1.8d593c

FS5%445a11de71d 1.1e873b

Means(n=3)followed by same letter within a row are not signi?cantly different(p>0.05).

LS,Limestone;RM,Red-mud;and FS,Furnace slag.

URE,urease;PME,phosphatase;DHA,dehydrogenase.

TPF,triphenyl formazan;NP,nitrophenol.

Table4

Correlation coef?cients between heavy-metal concentrations in soil and microbial activities and lettuce shoot concentrations(n=21).

Heavy-metals fraction Respiration Microbial biomass Soil enzyme Heavy-metals in lettuce shoot

URE PME DHA

DW-extractable Cdà0.446**à0.418à0.625**à0.056à0.2910.831**

Pbà0.713**0.262à0.579**à0.025à0.1610.307

Znà0.378à0.283à0.154à0.081à0.1640.645** Ca(NO3)2extractable Cdà0.728**à0.089à0.808**à0.416**à0.750**0.958**

Pbà0.687**à0.189à0.697**à0.292à0.686**0.654**

Znà0.685**à0.172à0.744**à0.393à0.749**0.930** Total Cdà0.249à0.088à0.625**à0.255à0.679**0.487*

Pbà0.625**0.449*à0.561**à0.38à0.575**0.342

Znà0.421*à0.263à0.392à0.093à0.1690.187

URE,urease;PME,phosphatase;DHA,dehydrogenase.

*Signi?cant at p<0.05.

**Signi?cant at p<0.01.

S.-H.Lee et al./Chemosphere77(2009)1069–10751073

Sequential extractions generally distinguish only operationally de?ned fractions(Nirel and Morel,1990).However,because of the comparative nature of this study,sequential fractionation pro-vided some evidence of the mechanism of?xation following soil amendment applications.Our results suggest that the pH increase caused by the alkaline amendments led to an increase of metals associated with carbonated fractions.Moreover,red-mud and fur-nace slag,which are rich in Fe oxides with reactive surface sites able to bind metals(Table1),caused more metals to be associated with the Fe–Mn oxide fraction.

Although furnace slag contains a signi?cant amount of Fe,it does not provide heavy-metal accessible sites,because the Fe com-ponent of furnace slag is relatively fresh.Thus,time is needed to form new Fe oxides,i.e.,slag must corrode to form adsorption sites.

Among the important criteria for evaluating alternative remedi-ation technologies are reductions in contaminant solubility and bioavailability,demonstrated by chemical immobilization,and long-term effectiveness and permanence.One way to evaluate the stability of immobilization products may be to determine the ability of heavy metals to remain insoluble(not extractable)upon acidi?cation.The amendments we tested had different effects on remobilization by sudden acidi?cation(Fig.2).In furnace slag-amended soil,the change in the solubility of Cd,Pb,and Zn in re-sponse to a pH change was similar to that of non-amended soil. In contrast,the extractability of metals from red-mud-amended soil was lower than that from other amended soils undergoing the same acid treatment.Thus,red-mud has a high capacity for pH change resistance and metal sorption.This was further con-?rmed by the fact that red-mud was the only amendment that re-duced PBET Pb.

Soil microbial activity correlated positively with soil pH(r2 value was0.789,0.891,0.540,and0.825for respiration,urease, phosphatase,and dehydrogenase,respectively),suggesting the importance of the pH increase on microbial activities due to the amendments addition.At the same time,the increase in soil pH implies a reduction of the available heavy-metal fractions,which in turn reduces heavy-metal toxicity to microorganisms.It is dif?-cult to discriminate pH and metal effects,it can be said that they have similar effects on microbial community structure and activity. It was shown that increase in soil pH can alter the microbial com-munity towards more mainly Gram negative and fewer Gram posi-tive bacteria(B??t et al.,1995).The pH increase induced by amendments addition?rstly favored heavy-metal precipitation. Moreover,this could have resulted in an increase in heavy-metal sorption and decrease in bioavailable fraction of heavy metals,?nally mitigate the heavy-metal toxicity to microorganism.

There were strong negative correlations between Ca(NO3)2-extractable heavy-metals content and soil microbial activity(respi-ration,soil enzyme activity).The inhibition of microbial activities by metals in soil is principally attributed to an indirect effect(sup-pression of the microbial population and cellular activities)and/or a direct effect(inactivation of extracellular enzymes due to binding with metals).(Kizilkaya and Bayrakli,2005.)

Basal soil respiration and soil enzyme activity showed signi?-cant negative correlations with heavy-metals content,especially Ca(NO3)2-extractable heavy metals(Table4).Negative correlations between soil enzyme activity and heavy metals(Table4)have also been reported by Obbard(2001)and Kizilkaya et al.(2004).Soil en-zymes are highly sensitive to heavy metals and have been recom-mended as standard biochemical indicators to assess the quality of soils polluted with heavy metals(Hinojosa et al.,2004;Hinojosa et al.,2008).Thus,characteristic microbiological measurements (e.g.,soil respiration and soil enzyme activity)are useful indicators of the re-establishment of biotic connections and restoration func-tions in degraded systems.

Metal bioaccumulation factor in lettuce(ratio between metal concentration in lettuce and soil)showed large variability between the metals;from1.68to9.76for Cd,from0.01to0.04for Pb,and from0.18to0.65for Zn.It is known that the af?nity of metals for soil constituents has a crucial role in plant metal accumulation.The relative af?nity of metals was consistent with the value of the?rst hydrolysis constant(pK)of the cations proposed by Basta and Tabatabai(1992);Cu(pK=7.7)P Pb(pK=7.7)>Zn(pK=9.0)>Cd (pK=10.1).These data were also fairly consistent with the order of

1074S.-H.Lee et al./Chemosphere77(2009)1069–1075

bioconcentration factor values obtained in our experiments; Pb

The decreased uptake of metals by lettuce grown in amended soils is clearly related to the decrease of the phytoavailable fraction of metals.The most obvious effect was the signi?cant reduction of metal transfer in lettuce grown in soil amended with limestone and red-mud(Fig.3),as was also shown by Lombi et al.(2002). They also reported that heavy-metals content in lettuce shoots was greatly reduced by red-mud and limestone treatment.The 0.1M Ca(NO3)2fraction is the most available metal fraction in con-taminated soil and is related to phytotoxicity to lettuce(Table4) (Basta et al.,2000).

Although soil amendments signi?cantly reduce the concentra-tion of metals in lettuce and therefore the potential transfer of metals in the food chain,this reduction is not suf?cient to produce foodstuffs.Thus it can be said that this soil should not used for agriculture and/or no crops are cultivated for food production.

Numerous mechanisms have been proposed to explain the de-crease of heavy-metals availability in amended soils.We suggest that the immobilization of heavy metals in this experiment re-sulted from two processes.First,the increased soil pH associated with the application of alkaline amendments reduced heavy-metal solubility in soil and increased metal sorption to soil particles be-cause of the net negative charge increase of variably charged col-loids,such as clays,organic matter,and Fe and Al oxides (McBride et al.,1997).Also,increased soil pH and carbonate buffer-ing can lead to the formation of metal–carbonate precipitate com-plexes that decrease metal availability(McBride,1989).

Second,the large amount of Fe and Al oxides in red-mud and furnace slag introduce new sorptive surfaces that may immobilize heavy metals in soils through speci?c sorptions or chemisorptions (Lombi et al.,2002).

We did not ascertain how much of the post-amendment de-crease in metal availability was due to increased soil pH rather than speci?c sorption.However,depending on the mechanisms in-volved,changes in soil properties(i.e.,pH)appear to have different effects on the long-term stability of amendments.Over a longer time scale,the pH of limestone and red-mud may change from alkaline to acidic because of long-term weathering transforma-tions.Further research should investigate the potential of amend-ments to reduce heavy-metals availability over a longer term. References

B??t, E.,Frosteg?rd,?.,Pennanen,T.,Fritze,H.,1995.Microbial community structure and pH response in relation to soil organic matter quality in wood-ash fertilized,clear-cut or burned coniferous soil.Soil Biol.Biochem.27,229–240.

Basta,N.T.,McGowen,S.L.,2004.Evaluation of chemical immobilization treatments for reducing heavy metal transport in a smelter-contaminated soil.Environ.

Pollut.127,73–82.

Basta,N.T.,Tabatabai,M.A.,1992.Effect of cropping systems on adsorption of metals by soils.II.Effect of pH.Soil Sci.153,195–204.

Basta,N.T.,Gradwohl,R.,Snethen,K.L.,Schroder,J.,2000.Chemical immobilization of lead,zinc and cadmium in smelter-contaminated soils using biosolids and rock phosphates.J.Environ.Qual.30,1222–1230.

Brown,S.,Chaney,R.,Hallfrisch,J.,Ryan,J.A.,Berti,W.R.,2004.In situ treatments to reduce the phyto-and bioavailability of lead,zinc and cadmium.J.Environ.

Qual.33,522–531.

Brown,S.,Sprenger,M.,Maxemchuk,A.,Compton,H.,2005.Ecosystem function in alluvial tailing after biosolids and lime addition.J.Environ.Qual.34,139–148. Casida,L.E.,Klein,D.A.,Santoro,T.,1964.Soil dehydrogenase activity.Soil Sci.Soc.

Am.J.47,599–603.

Chen,H.M.,Zheng, C.R.,Tu, C.,Shen,Z.G.,2000.Chemical methods and phytostabilization of soil contaminated with heavy metals.Chemosphere41, 229–234.Conder,J.M.,Lanno,R.P.,Basta,N.T.,2001.Assessment of metal availability in smelter soil using earthworms and chemical extractant.J.Environ.Qual.30, 1231–1237.

Dorn,P.B.,Salanitro,J.P.,2000.Temporal ecotoxicological assessments of oil contaminated soils before and after bioremediation.Chemosphere40,419–426. Gee,G.W.,Bauder,J.W.,1986.Particle size analysis.In:Klute,A.(Ed.),Methods of Soil Analysis.Part I.Physical and mineralogical methods.ASA-SSAA,Madison, Wisconsin,USA,pp.383–411.

Geebelen,W.,Adriano,D.C.,van der Lelie,D.,Mench,M.,Carleer,R.,Clijsters,H., Vangronsveld,J.,2003.Selected bioavailability assays to test the effect of amendment-induced immobilization of lead in soils.Plant Soil249,217–228. Giusquiani,P.L.,Concezzi,L.,Businelli,M.,Macchioni,A.,1998.Fate of pig sludge liquid fraction in calcareous soil:agricultural and environmental implications.J.

Environ.Qual.27,364–371.

Gray,C.W.,Dunhan,S.J.,Dennis,P.G.,Zhao,F.J.,McGrath,S.P.,2006.Field evaluation of in situ remediation of a heavy metal contaminated soil using lime and red-mud.Environ.Pollut.142,530–539.

Hinojosa,M.B.,Carreira,J.A.,García-Ruíz,R.,Dick,R.P.,2004.Soil moisture pretreatment effects on enzyme activities as indicators of heavy metal-contaminated and reclaimed soils.Soil Biol.Biochem.36,1559–1568. Hinojosa,M.B.,Carreira,J.A.,Rodríguez-Maroto,J.M.,García-Ruíz,R.,2008.Effects of pyrite sludge pollution on soil enzyme activities:ecological dose–response model.Sci.Total Environ.396,89–99.

Kandeler, E.,1995.Enzymes involved in nitrogen metabolism.In:Schinner, F., Ohlinger,R.,Kandeler,E.,Margesin,R.(Eds.),Methods in Soil Biology.Springer-Verlag,Berlin Heidelberg,pp.171–176.

Kizilkaya,R.,Bayrakli,B.,2005.Effects of N-enriched sewage sludge on soil enzyme activities.Appl.Soil Ecol.30,192–202.

Kizilkaya,R.,As?kin,T.,Bayrakli,B.,Sag?lam,M.,2004.Microbiological characteristics of soils contaminated with heavy metals.Eur.J.Soil Biol.40,95–102. Leitgib,L.,Kálmán,J.,Gruiz,K.,https://www.sodocs.net/doc/1713756845.html,parison of bioassays by testing whole soil and their water extract from contaminated sites.Chemosphere66,428–434. Lombi,E.,Zhao,F.-J.,Zhang,G.,Sun,B.,Fitz,W.,Zhang,H.,McGrath,S.P.,2002.In situ?xation of metals in soils using bauxite residue:chemical assessment.

Environ.Pollut.118,435–443.

McBride,M.B.,1989.Reactions controlling heavy metal solubility in soils.Adv.Soil Sci.10,1–56.

McBride,M.B.,Suave,S.,Hendershot,W.,1997.Solubility control of Cu,Zn,Cd,and Pb in contaminated soils.Eur.J.Soil Sci.48,337–346.

McLaughlin,M.J.,Zarcinas,B.A.,Stevens,D.P.,Cook,N.,2000.Soil testing for heavy https://www.sodocs.net/doc/1713756845.html,mun.Soil Sci.Plan31,1661–1700.

Mench,M.,Manceau,A.,Vangronsveld,J.,Clijsters,H.,Mocquot,B.,2000.Capacity of soil amendments in lowering the phytoavailability of sludge borne zinc.

Agronomie20,383–397.

Mremner,J.M.,1996.Nitrogen-total.In:Sparks,D.L.(Ed.),Method of Soil Analysis: Chemical Methods.American Society of Agronomy,Madison,WI,pp.1085–1121.

Nelson,D.W.,Sommers,L.E.,1996.Total carbon,organic carbon,and organic matter.

In:Sparks,D.L.(Ed.),Method of Soil Analysis:Chemical Methods.American Society of Agronomy,Madison,WI,pp.1201–1229.

Nirel,P.M.V.,Morel,F.M.M.,1990.Pitfalls of sequential extraction.Water Res.24, 1055–1056.

Obbard,J.P.,2001.Ecotoxicological assessment of heavy metals in sewage sludge amended soil.Appl.Geochem.16,1405–1411.

Oste,L.,Lexmond,T.M.,van Riemsdijk,W.H.,2002.Metal immobilization in soils using synthetic zeolites.J.Environ.Qual.31,813–821.

Pérez-de-Mora,A.,Ortega-Calvo,J.J.,Cabrera, F.,Madejón, E.,2005.Changes in enzyme activities and microbial biomass after‘‘in-situ”remediation of a heavy metal-contaminated soil.Appl.Soil Ecol.28,125–137.

Scott-Fordsmand,J.J.,Weeks,J.M.,Hopkin,S.P.,2000.Importance of contamination history for understanding toxicity of copper to earthworm Eisenia fetida (Oligochaeta:annelida),using neutral red retention assay.Environ.Toxicol.

Chem.19,1774–1780.

Sumner,M.E.,Miller,W.P.,1996.Cation exchange capacity and exchange coef?cients.In:Sparks,D.L.(Ed.),Method of Soil Analysis:Chemical Methods.

American Society of Agronomy,Madison,WI,pp.1201–1229.

Tabatabai,M.A.,Bremner,J.M.,https://www.sodocs.net/doc/1713756845.html,e of p-nitrophenyl phosphate for assay of soil phosphatase activity.Soil Biol.Biochem.1,301–307.

Tejada,M.,Hernandez,M.T.,Garcia, C.,2006.Application of two organic amendments on soil restoration:effects on the biological properties.J.

Environ.Qual.35,1010–1017.

Tessier,A.,Campbell,P.G.C.,Bisson,M.,1979.Sequential extraction procedure for the speciation of particulate trace metals.Anal.Chem.51,844–851. Thomas,G.W.,1996.Soil pH and soil acidity.In:Sparks,D.L.(Ed.),Methods of Soil Analysis:Chemical Methods.American Society of Agronomy,Madison,WI,pp.

475–490.

US Environmental Protection Agency,1986.Test Methods for Evaluating Solid https://www.sodocs.net/doc/1713756845.html,boratory Manual Physical/Chemical Methods,https://www.sodocs.net/doc/1713756845.html, Govt.Print.

Of?ce,Washington,DC(SW-846).

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英语中的比较级与最高级 详解

比较级与最高级 1.as...as 与(not) as(so)...as as...as...句型中,as的词性 第一个as是副词,用在形容词和副词的原级前,常译为“同样地”。第二个as是连词,连接与前面句子结构相同的一个句子(相同部分常省略),可译为“同..... He is as tall as his brother is (tall) . (后面的as 为连词) 只有在否定句中,第一个as才可换为so 改错: He is so tall as his brother.(X) 2.在比较状语从句中,主句和从句的句式结构一般是相同的 与as...as 句式中第二个as一样,than 也是连词。as和than这两个连词后面的从句的结构与前面的句子大部分情况下结构是相同的,相同部分可以省略。 He picked more apples than she did. 完整的表达为: He picked more apples than she picked apples. 后而的picked apples和前面相同,用did 替代。 He walked as slowly as she did.完整表达为: He walked as slowly as she walked slowly. she后面walked slowly与前面相同,用did替代。

3.谓语的替代 在as和than 引导的比较状语从句中,由于句式同前面 主句相同,为避免重复,常把主句中出现而从句中又出现的动词用do的适当形式来代替。 John speaks German as fluently as Mary does. 4.前后的比较对象应一致 不管后面连词是than 还是as,前后的比较对象应一致。The weather of Beijing is colder than Guangzhou. x than前面比较对象是“天气”,than 后面比较对象是“广州”,不能相比较。应改为: The weather of Bejing is colder than that of Guangzhou. 再如: His handwriting is as good as me. 应改为: His handwriting is as good as mine. 5.可以修饰比较级的词 常用来修饰比较级的词或短语有: Much,even,far,a little,a lot,a bit,by far,rather,any,still,a great deal等。 by far的用法: 用于强调,意为“...得多”“最最...”“显然”等,可修饰形容词或副词的比较级和最高级,通常置于其后,但是若比较级或最高级前有冠词,则可置于其前或其后。

The way常见用法

The way 的用法 Ⅰ常见用法: 1)the way+ that 2)the way + in which(最为正式的用法) 3)the way + 省略(最为自然的用法) 举例:I like the way in which he talks. I like the way that he talks. I like the way he talks. Ⅱ习惯用法: 在当代美国英语中,the way用作为副词的对格,“the way+ 从句”实际上相当于一个状语从句来修饰整个句子。 1)The way =as I am talking to you just the way I’d talk to my own child. He did not do it the way his friends did. Most fruits are naturally sweet and we can eat them just the way they are—all we have to do is to clean and peel them. 2)The way= according to the way/ judging from the way The way you answer the question, you are an excellent student. The way most people look at you, you’d think trash man is a monster. 3)The way =how/ how much No one can imagine the way he missed her. 4)The way =because

人教版(新目标)初中英语形容词与副词的比较级与最高级

人教版(新目标)初中英语形容词与副词的比较级与最高级 (一)规则变化: 1.绝大多数的单音节和少数双音节词,加词尾-er ,-est tall—taller—tallest 2.以不发音的e结尾的单音节词和少数以-le结尾的双音节词只加-r,-st nice—nicer—nicest , able—abler—ablest 3.以一个辅音字母结尾的重读闭音节词或少数双音节词,双写结尾的辅音字母,再加-er,-est big—bigger—biggest 4.以辅音字母加y结尾的双音节词,改y为i再加-er,-est easy—easier—easiest 5.少数以-er,-ow结尾的双音节词末尾加-er,-est clever—cleverer—cleverest, narrow—narrower—narrowest 6.其他双音节词和多音节词,在前面加more,most来构成比较级和最高级 easily—more easily—most easily (二)不规则变化 常见的有: good / well—better—best ; bad (ly)/ ill—worse—worst ; old—older/elder—oldest/eldest many / much—more—most ; little—less—least ; far—farther/further—farthest/furthest

用法: 1.原级比较:as + adj./adv. +as(否定为not so/as + adj./adv. +as)当as… as中间有名字时,采用as + adj. + a + n.或as + many / much + n. This is as good an example as the other is . I can carry as much paper as you can. 表示倍数的词或其他程度副词做修饰语时放在as的前面 This room is twice as big as that one. 倍数+as+adj.+as = 倍数+the +n.+of Your room is twice as larger as mine. = Your room is twice the size of mine. 2.比较级+ than 比较级前可加程度状语much, still, even, far, a lot, a little, three years. five times,20%等 He is three years older than I (am). 表示“(两个中)较……的那个”时,比较级前常加the(后面有名字时前面才能加冠词) He is the taller of the two brothers. / He is taller than his two brothers. Which is larger, Canada or Australia? / Which is the larger country, Canada or Australia? 可用比较级形式表示最高级概念,关键是要用或或否定词等把一事物(或人)与其他同类事物(或人)相分离 He is taller than any other boy / anybody else.

英语中的比较级和最高级

大多数形容词有三种形式,原级,比较级和最高级, 以表示形容词说明的性质在程度上的不同。 形容词的原级: 形容词的原级形式就是词典中出现的形容词的原形。例如: poor tall great glad bad 形容词的比较级和最高级: 形容词的比较级和最高级形式是在形容词的原级形式的基础上变化的。分为规则变化和不规则变化。 规则变化如下: 1) 单音节形容词的比较级和最高级形式是在词尾加 -er 和 -est 构成。 great (原级) (比较级) (最高级) 2) 以 -e 结尾的单音节形容词的比较级和最高级是在词尾加 -r 和 -st 构成。wide (原级) (比较级) (最高级) 3)少数以-y, -er, -ow, -ble结尾的双音节形容词的比较级和最高级是在词尾加 -er 和 -est 构成。 clever(原级) (比较级) (最高级) 4) 以 -y 结尾,但 -y 前是辅音字母的形容词的比较级和最高级是把 -y 去掉,加上 -ier 和-est 构成. happy (原形) (比较级) (最高级) 5) 以一个辅音字母结尾其前面的元音字母发短元音的形容词的比较级和最高级是双写该辅音字母然后再加 -er和-est。 big (原级) (比较级) (最高级) 6) 双音节和多音节形容词的比较级和最高级需用more 和 most 加在形容词前面来构成。 beautiful (原级) (比较级) (比较级) difficult (原级) (最高级) (最高级) 常用的不规则变化的形容词的比较级和最高级: 原级------比较级------最高级 good------better------best many------more------most much------more------most bad------worse------worst far------farther, further------farthest, furthest 形容词前如加 less 和 least 则表示"较不"和"最不 形容词比较级的用法: 形容词的比较级用于两个人或事物的比较,其结构形式如下: 主语+谓语(系动词)+ 形容词比较级+than+ 对比成分。也就是, 含有形容词比较级的主句+than+从句。注意从句常常省去意义上和主句相同的部分, 而只剩下对比的成分。

The way的用法及其含义(二)

The way的用法及其含义(二) 二、the way在句中的语法作用 the way在句中可以作主语、宾语或表语: 1.作主语 The way you are doing it is completely crazy.你这个干法简直发疯。 The way she puts on that accent really irritates me. 她故意操那种口音的样子实在令我恼火。The way she behaved towards him was utterly ruthless. 她对待他真是无情至极。 Words are important, but the way a person stands, folds his or her arms or moves his or her hands can also give us information about his or her feelings. 言语固然重要,但人的站姿,抱臂的方式和手势也回告诉我们他(她)的情感。 2.作宾语 I hate the way she stared at me.我讨厌她盯我看的样子。 We like the way that her hair hangs down.我们喜欢她的头发笔直地垂下来。 You could tell she was foreign by the way she was dressed. 从她的穿著就可以看出她是外国人。 She could not hide her amusement at the way he was dancing. 她见他跳舞的姿势,忍俊不禁。 3.作表语 This is the way the accident happened.这就是事故如何发生的。 Believe it or not, that's the way it is. 信不信由你, 反正事情就是这样。 That's the way I look at it, too. 我也是这么想。 That was the way minority nationalities were treated in old China. 那就是少数民族在旧中

英语比较级和最高级的用法归纳

英语比较级和最高级的用法归纳 在学习英语过程中,会遇到很多的语法问题,比如比较级和最高级的用法,对于 这些语法你能够掌握吗?下面是小编整理的英语比较级和最高级的用法,欢迎阅读! 英语比较级和最高级的用法 一、形容词、副词的比较级和最高级的构成规则 1.一般单音节词和少数以-er,-ow结尾的双音节词,比较级在后面加-er,最高级 在后面加-est; (1)单音节词 如:small→smaller→smallest short→shorter→shortest tall→taller→tallest great→greater→greatest (2)双音节词 如:clever→cleverer→cleverest narrow→narrower→narrowest 2.以不发音e结尾的单音节词,比较在原级后加-r,最高级在原级后加-st; 如:large→larger→largest nice→nicer→nicest able→abler→ablest 3.在重读闭音节(即:辅音+元音+辅音)中,先双写末尾的辅音字母,比较级加-er,最高级加-est; 如:big→bigger→biggest hot→hotter→hottest fat→fatter→fattest 4.以“辅音字母+y”结尾的双音节词,把y改为i,比较级加-er,最高级加-est; 如:easy→easier→easiest heavy→heavier→heaviest busy→busier→busiest happy→happier→happiest 5.其他双音节词和多音节词,比较级在前面加more,最高级在前面加most; 如:bea utiful→more beautiful→most beautiful different→more different→most different easily→more easily→most easily 注意:(1)形容词最高级前通常必须用定冠词 the,副词最高级前可不用。 例句: The Sahara is the biggest desert in the world. (2) 形容词most前面没有the,不表示最高级的含义,只表示"非常"。 It is a most important problem. =It is a very important problem.

(完整版)the的用法

定冠词the的用法: 定冠词the与指示代词this ,that同源,有“那(这)个”的意思,但较弱,可以和一个名词连用,来表示某个或某些特定的人或东西. (1)特指双方都明白的人或物 Take the medicine.把药吃了. (2)上文提到过的人或事 He bought a house.他买了幢房子. I've been to the house.我去过那幢房子. (3)指世界上独一无二的事物 the sun ,the sky ,the moon, the earth (4)单数名词连用表示一类事物 the dollar 美元 the fox 狐狸 或与形容词或分词连用,表示一类人 the rich 富人 the living 生者 (5)用在序数词和形容词最高级,及形容词等前面 Where do you live?你住在哪? I live on the second floor.我住在二楼. That's the very thing I've been looking for.那正是我要找的东西. (6)与复数名词连用,指整个群体 They are the teachers of this school.(指全体教师) They are teachers of this school.(指部分教师) (7)表示所有,相当于物主代词,用在表示身体部位的名词前 She caught me by the arm.她抓住了我的手臂. (8)用在某些有普通名词构成的国家名称,机关团体,阶级等专有名词前 the People's Republic of China 中华人民共和国 the United States 美国 (9)用在表示乐器的名词前 She plays the piano.她会弹钢琴. (10)用在姓氏的复数名词之前,表示一家人 the Greens 格林一家人(或格林夫妇) (11)用在惯用语中 in the day, in the morning... the day before yesterday, the next morning... in the sky... in the dark... in the end... on the whole, by the way...

英语比较级和最高级的用法

More than的用法 A. “More than+名词”表示“不仅仅是” 1)Modern science is more than a large amount of information. 2)Jason is more than a lecturer; he is a writer, too. 3) We need more than material wealth to build our country.建设我们国家,不仅仅需要物质财富. B. “More than+数词”含“以上”或“不止”之意,如: 4)I have known David for more than 20 years. 5)Let's carry out the test with more than the sample copy. 6) More than one person has made this suggestion. 不止一人提过这个建议. C. “More than+形容词”等于“很”或“非常”的意思,如: 7)In doing scientific experiments, one must be more than careful with the instruments. 8)I assure you I am more than glad to help you. D. more than + (that)从句,其基本意义是“超过(=over)”,但可译成“简直不”“远非”.难以,完全不能(其后通常连用情态动词can) 9) That is more than I can understand . 那非我所能懂的. 10) That is more than I can tell. 那事我实在不明白。 11) The heat there was more than he could stand. 那儿的炎热程度是他所不能忍受的 此外,“more than”也在一些惯用语中出现,如: more...than 的用法 1. 比……多,比……更 He has more books than me. 他的书比我多。 He is more careful than the others. 他比其他人更仔细。 2. 与其……不如 He is more lucky than clever. 与其说他聪明,不如说他幸运。 He is more (a)scholar than (a)teacher. 与其说他是位教师,不如说他是位学者。 注:该句型主要用于同一个人或物在两个不同性质或特征等方面的比较,其中的比较级必须用加more 的形式,不能用加词尾-er 的形式。 No more than/not more than 1. no more than 的意思是“仅仅”“只有”“最多不超过”,强调少。如: --This test takes no more than thirty minutes. 这个测验只要30分钟。 --The pub was no more than half full. 该酒吧的上座率最多不超过五成。-For thirty years,he had done no more than he (had)needed to. 30年来,他只干了他需要干的工作。 2. not more than 为more than (多于)的否定式,其意为“不多于”“不超过”。如:Not more than 10 guests came to her birthday party. 来参加她的生日宴会的客人不超过十人。 比较: She has no more than three hats. 她只有3顶帽子。(太少了) She has not more than three hats. 她至多有3顶帽子。(也许不到3顶帽子) I have no more than five yuan in my pocket. 我口袋里的钱最多不过5元。(言其少) I have not more than five yuan in my pocket. 我口袋里的钱不多于5元。(也许不到5元) more than, less than 的用法 1. (指数量)不到,不足 It’s less than half an hour’s drive from here. 开车到那里不到半个钟头。 In less than an hour he finished the work. 没要上一个小时,他就完成了工作。 2. 比……(小)少 She eats less than she should. 她吃得比她应该吃的少。 Half the group felt they spent less than average. 半数人觉得他们的花费低于平均水平。 more…than,/no more than/not more than (1)Mr.Li is ________ a professor; he is also a famous scientist. (2)As I had ________ five dollars with me, I couldn’t afford the new jacket then. (3)He had to work at the age of ________ twelve. (4)There were ________ ten chairs in the room.However, the number of the children is twelve. (5)If you tel l your father what you’ve done, he’ll be ________ angry. (6)-What did you think of this novel? -I was disappointed to find it ________ interesting ________ that one. 倍数表达法 1. “倍数+形容词(或副词)的比较级+than+从句”表示“A比B大(长、高、宽等)多少倍” This rope is twice longer than that one.这根绳是那根绳的三倍(比那根绳长两倍)。The car runs twice faster than that truck.这辆小车的速度比那辆卡车快两倍(是那辆卡车的三倍)。 2. “倍数+as+形容词或副词的原级+as+从句”表示“A正好是B的多少倍”。

“the way+从句”结构的意义及用法

“theway+从句”结构的意义及用法 首先让我们来看下面这个句子: Read the followingpassageand talkabout it wi th your classmates.Try totell whatyou think of Tom and ofthe way the childrentreated him. 在这个句子中,the way是先行词,后面是省略了关系副词that或in which的定语从句。 下面我们将叙述“the way+从句”结构的用法。 1.the way之后,引导定语从句的关系词是that而不是how,因此,<<现代英语惯用法词典>>中所给出的下面两个句子是错误的:This is thewayhowithappened. This is the way how he always treats me. 2.在正式语体中,that可被in which所代替;在非正式语体中,that则往往省略。由此我们得到theway后接定语从句时的三种模式:1) the way+that-从句2)the way +in which-从句3) the way +从句 例如:The way(in which ,that) thesecomrade slookatproblems is wrong.这些同志看问题的方法

不对。 Theway(that ,in which)you’re doingit is comple tely crazy.你这么个干法,简直发疯。 Weadmired him for theway inwhich he facesdifficulties. Wallace and Darwingreed on the way inwhi ch different forms of life had begun.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 This is the way(that) hedid it. I likedthe way(that) sheorganized the meeting. 3.theway(that)有时可以与how(作“如何”解)通用。例如: That’s the way(that) shespoke. = That’s how shespoke.

初中英语比较级和最高级讲解与练习

初中英语比较级和最高级讲解与练习 形容词比较级和最高级 一.绝大多数形容词有三种形式,原级,比较级和最高级, 以表示形容词说明的性质在程度上的不同。 1. 形容词的原级: 形容词的原级形式就是词典中出现的形容词的原形。例如: poor tall great glad bad 2. 形容词的比较级和最高级: 形容词的比较级和最高级形式是在形容词的原级形式的基 础上变化的。分为规则变化和不规则变化。 二.形容词比较级和最高级规则变化如下: 1) 单音节形容词的比较级和最高级形式是在词尾加-er 和-est 构成。 great (原级) greater(比较级) greatest(最高级) 2) 以-e 结尾的单音节形容词的比较级和最高级是在词尾加-r 和-st 构成。 wide (原级) wider (比较级) widest (最高级) 3) 少数以-y, -er, -ow, -ble结尾的双音节形容词的比较级和最高级是在词尾加 -er 和-est构成。 clever(原级) cleverer(比较级) cleverest(最高级), slow(原级) slower(比较级) slowest (最高级) 4) 以-y 结尾,但-y 前是辅音字母的形容词的比较级和最高级是把-y 去掉,加上-ier 和-est 构成. happy (原形) happier (比较级) happiest (最高级) 5) 以一个辅音字母结尾其前面的元音字母发短元音的形容词的比较级和最高级是双写该 辅音字母然后再加-er和-est。 原形比较级最高级原形比较级最高级 big bigger biggest hot hotter hottest red redder reddest thin thinner thinnest 6) 双音节和多音节形容词的比较级和最高级需用more 和most 加在形容词前面来构 成。 原形比较级最高级 careful careful more careful most careful difficult more difficult most difficult delicious more delicious most delicious 7)常用的不规则变化的形容词的比较级和最高级: 原级比较级最高级 good better best 好的 well better best 身体好的 bad worse worst 坏的 ill worse worst 病的 many more most 许多 much more most 许多 few less least 少数几个 little less least 少数一点儿 (little littler littlest 小的) far further furthest 远(指更进一步,深度。亦可指更远) far farther farthest 远(指更远,路程)

way 用法

表示“方式”、“方法”,注意以下用法: 1.表示用某种方法或按某种方式,通常用介词in(此介词有时可省略)。如: Do it (in) your own way. 按你自己的方法做吧。 Please do not talk (in) that way. 请不要那样说。 2.表示做某事的方式或方法,其后可接不定式或of doing sth。 如: It’s the best way of studying [to study] English. 这是学习英语的最好方法。 There are different ways to do [of doing] it. 做这事有不同的办法。 3.其后通常可直接跟一个定语从句(不用任何引导词),也可跟由that 或in which 引导的定语从句,但是其后的从句不能由how 来引导。如: 我不喜欢他说话的态度。 正:I don’t like the way he spoke. 正:I don’t like the way that he spoke. 正:I don’t like the way in which he spoke. 误:I don’t like the way how he spoke. 4.注意以下各句the way 的用法: That’s the way (=how) he spoke. 那就是他说话的方式。 Nobody else loves you the way(=as) I do. 没有人像我这样爱你。 The way (=According as) you are studying now, you won’tmake much progress. 根据你现在学习情况来看,你不会有多大的进步。 2007年陕西省高考英语中有这样一道单项填空题: ——I think he is taking an active part insocial work. ——I agree with you_____. A、in a way B、on the way C、by the way D、in the way 此题答案选A。要想弄清为什么选A,而不选其他几项,则要弄清选项中含way的四个短语的不同意义和用法,下面我们就对此作一归纳和小结。 一、in a way的用法 表示:在一定程度上,从某方面说。如: In a way he was right.在某种程度上他是对的。注:in a way也可说成in one way。 二、on the way的用法 1、表示:即将来(去),就要来(去)。如: Spring is on the way.春天快到了。 I'd better be on my way soon.我最好还是快点儿走。 Radio forecasts said a sixth-grade wind was on the way.无线电预报说将有六级大风。 2、表示:在路上,在行进中。如: He stopped for breakfast on the way.他中途停下吃早点。 We had some good laughs on the way.我们在路上好好笑了一阵子。 3、表示:(婴儿)尚未出生。如: She has two children with another one on the way.她有两个孩子,现在还怀着一个。 She's got five children,and another one is on the way.她已经有5个孩子了,另一个又快生了。 三、by the way的用法

英语比较级和最高级

形容词比较级和最高级的形式 一、形容词比较级和最高级的构成 形容词的比较级和最高级变化形式规则如下 构成法原级比较级最高级 ①一般单音节词末尾加 er 和 est strong stronger strongest ②单音节词如果以 e结尾,只加 r 和 st strange stranger strangest ③闭音节单音节词如末尾只有一个辅音字母, 须先双写这个辅音字母,再加 er和 est sad big hot sadder bigger hotter saddest biggest hottest ④少数以 y, er(或 ure), ow, ble结尾的双音节词, 末尾加 er和 est(以 y结尾的词,如 y前是辅音字母, 把y变成i,再加 er和 est,以 e结尾的词仍 只加 r和 st) angry Clever Narrow Noble angrier Cleverer narrower nobler angriest cleverest narrowest noblest ⑤其他双音节和多音节词都在前面加单词more和most different more different most different 1) The most high 〔A〕mountain in 〔B〕the world is Mount Everest,which is situated 〔C〕in Nepal and is twenty nine thousand one hundred and fourty one feet high 〔D〕 . 2) This house is spaciouser 〔A〕than that 〔B〕white 〔C〕one I bought in Rapid City,South Dakota 〔D〕last year. 3) Research in the social 〔A〕sciences often proves difficulter 〔B〕than similar 〔C〕work in the physical 〔D〕sciences. 二、形容词比较级或最高级的特殊形式:

高中英语的比较级和最高级用法总结

比较级和最高级 1.在形容词词尾加上―er‖ ―est‖ 构成比较级、最高级: bright(明亮的)—brighter—brightest broad(广阔的)—broader—broadest cheap(便宜的)—cheaper—cheapest clean(干净的)—cleaner—cleanest clever(聪明的)—cleverer—cleverest cold(寒冷的)—colder—coldest cool(凉的)—cooler—coolest dark(黑暗的)—darker—darkest dear(贵的)—dearer—dearest deep(深的)—deeper—deepest fast(迅速的)—faster—fastest few(少的)—fewer—fewest great(伟大的)—greater—greatest hard(困难的,硬的)—harder—hardest high(高的)—higher—highest kind(善良的)—kinder—kindest light(轻的)—lighter—lightest long(长的)—longer—longest loud(响亮的)—louder—loudest low(低的)—lower—lowest near(近的)—nearer—nearest new(新的)—newer—newest poor(穷的)—poorer—poorest quick(快的)—quicker—quickest quiet(安静的)—quieter—quietest rich(富裕的)—richer—richest short(短的)—shorter—shortest slow(慢的)—slower—slowest small(小的)—smaller—smallest smart(聪明的)—smarter—smartest soft(柔软的)—softer—softest strong(强壮的)—stronger—strongest sweet(甜的)—sweeter—sweetest tall(高的)-taller-tallest thick(厚的)—thicker—thickest warm(温暖的)—warmer—warmest weak(弱的)—weaker—weakest young(年轻的)—younger—youngest 2.双写最后一个字母,再加上―er‖ ―est‖构成比较级、最高级: big(大的)—bigger—biggest fat(胖的)—fatter—fattest hot(热的)—hotter—hottest red(红的)—redder—reddest sad(伤心的)—sadder—saddest thin(瘦的)—thinner—thinnest wet(湿的)—wetter—wettest mad(疯的)—madder—maddest 3.以不发音的字母e结尾的形容词,加上―r‖ ―st‖ 构成比较级、最高级:able(能干的)—abler—ablest brave(勇敢的)—braver—bravest close(接近的)—closer—closest fine(好的,完美的)—finer—finest large(巨大的)—larger—largest late(迟的)—later—latest nice(好的)—nicer—nicest ripe(成熟的)—riper—ripest

The way的用法及其含义(一)

The way的用法及其含义(一) 有这样一个句子:In 1770 the room was completed the way she wanted. 1770年,这间琥珀屋按照她的要求完成了。 the way在句中的语法作用是什么?其意义如何?在阅读时,学生经常会碰到一些含有the way 的句子,如:No one knows the way he invented the machine. He did not do the experiment the way his teacher told him.等等。他们对the way 的用法和含义比较模糊。在这几个句子中,the way之后的部分都是定语从句。第一句的意思是,“没人知道他是怎样发明这台机器的。”the way的意思相当于how;第二句的意思是,“他没有按照老师说的那样做实验。”the way 的意思相当于as。在In 1770 the room was completed the way she wanted.这句话中,the way也是as的含义。随着现代英语的发展,the way的用法已越来越普遍了。下面,我们从the way的语法作用和意义等方面做一考查和分析: 一、the way作先行词,后接定语从句 以下3种表达都是正确的。例如:“我喜欢她笑的样子。” 1. the way+ in which +从句 I like the way in which she smiles. 2. the way+ that +从句 I like the way that she smiles. 3. the way + 从句(省略了in which或that) I like the way she smiles. 又如:“火灾如何发生的,有好几种说法。” 1. There were several theories about the way in which the fire started. 2. There were several theories about the way that the fire started.

(完整版)初中英语比较级和最高级的用法

英语语法---比较级和最高级的用法 在英语中通常用下列方式表示的词:在形容词或副词前加more(如 more natural,more clearly )或加后缀 -er(newer,sooner )。典型的是指形容词或副词所表示的质、量或关系的增加。英语句子中,将比较两个主体的方法叫做“比较句型”。其中,像“A比B更……”的表达方式称为比较级;而“A最……”的表达方式则称为最高级。组成句子的方式是将形容词或副词变化成比较级或最高级的形态。 一、形容词、副词的比较级和最高级的构成规则 1.一般单音节词和少数以-er,-ow结尾的双音节词,比较级在后面加-er,最高级在后面加-est; (1)单音节词 如:small→smaller→smallest short→shorter→shortest tall→taller→tallest great→greater→greatest (2)双音节词 如:clever→cleverer→cleverest narrow→narrower→narrowest 2.以不发音e结尾的单音节词,比较在原级后加-r,最高级在原级后加-st; 如:large→larger→largest nice→nicer→nicest able→abler→ablest 3.在重读闭音节(即:辅音+元音+辅音)中,先双写末尾的辅音字母,比较级加-er,最高级加-est; 如:big→bigger→biggest hot→hotter→hottest fat→fatter→fattest 4.以“辅音字母+y”结尾的双音节词,把y改为i,比较级加-er,最高级加-est; 如:easy→easier→easiest heavy→heavier→heaviest busy→busier→busiest happy→happier→happiest 5.其他双音节词和多音节词,比较级在前面加more,最高级在前面加most; 如:beautiful→more beautiful→most beautiful different→more different→most different easily→more easily→most easily

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