Two-century sedimentary record of heavy metal pollution from Lake Sayram_ A deep mountain lakeChina

Two-century sedimentary record of heavy metal pollution from Lake Sayram:A deep mountain lake in central Tianshan,China

Haiao Zeng,Jinglu Wu*,Wen Liu

State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,73East Beijing Road, Nanjing210008,PR China

a r t i c l e i n f o

Article history:

Available online17October2013a b s t r a c t

A short sediment core from Lake Sayram,China,was used to develop a high-resolution record of heavy metal inputs from the Tianshan Mountains and the surrounding region over the last200years.We investigated metal inputs to Lake Sayram using the geo-accumulation index(Igeos)and enrichment factors(EFs).Anthropogenic metal?uxes were calculated to quantify the human contribution to heavy metal https://www.360docs.net/doc/1d13701116.html,ke Sayram has been polluted by Cd,As,Pb,and Hg since the1960s,and has had three distinct periods in its pollution history.Prior to1960,metals in Lake Sayram sediments were mainly from natural sources,with very low values of EFs and Igeos.From the1960s to1990s,heavy metal delivery to sediments increased slowly,associated with relatively weak economic development in Xinjiang Province, similar to other areas of China.Thereafter,contamination by heavy metals increased markedly,especially after https://www.360docs.net/doc/1d13701116.html,ke Sayram was considered to be moderately polluted by Cd,Hg,and Pb,and is moderately to strongly polluted by As at present.Contamination by heavy metals varied with economic development of Xinjiang Province.Between1990and2010,anthropogenic accumulation of Cd,As,Pb and Hg increased from4.05to7.30ng/cm2/y,0.27e0.98m g/cm2/y,0.21e0.39m g/cm2/y and0.61e0.83ng/ cm2/y,respectively.Furthermore,the206Pb/207Pb ratio demonstrates that coal burning emissions and Pb in vehicle gasoline were major sources of heavy metal pollution in the Tianshan Mountains region.

ó2013Elsevier Ltd and INQUA.All rights reserved.

1.Introduction

Heavy metals such as cadmium,lead,copper,mercury and zinc are important pollutants of aquatic ecosystems because of their environmental persistence,toxicity and potential for accumulation in food chains(Opfer et al.,2011;Copat et al.,2012).Human ac-tivities such as mining,smelting and?nishing,coal combustion, refuse incineration,and burning of fossil fuels have greatly increased the?uxes of heavy metals to aquatic environments(Han et al.,2007;Thevenon et al.,2011b).Heavy metals enter the aquatic system through surface runoff or atmospheric deposition and accumulate in sediments through adsorption and sedimentation of suspended matter.Thus,lake sediments are important sinks of heavy metals,re?ect the quality of aquatic systems,and provide long-term records of past environmental conditions.Stratigraphic analyses of heavy metals in lacustrine sediments can be used to reconstruct temporal variations in natural and anthropogenic in-puts to the lake ecosystems(Callender and Rice,2000;Dassenakis et al.,2003;Stéphane et al.,2004;Wu et al.,2007;Yuan et al.,2011; Thevenon et al.,2011b;Deepulal et al.,2012).

Recent studies suggest that mountain lakes that are relatively isolated from anthropogenic in?uence act as natural traps for atmospherically transported pollutants,and that metal concen-trations in their sediments can be as high as those in lakes of urban or industrial areas(Han et al.,2007;Rippey et al.,2008;Thevenon et al.,2011a).China has undergone rapid economic development in the past three decades,with an average annual Gross Domestic Product(GDP)growth rate>10%.Large amounts of hazardous materials,including heavy metals generated during industrial processes may move to remote regions and contribute to contam-ination of otherwise pristine environments.Thus,there is a need to quantify metal?uxes from anthropogenic emissions to mountain areas of China.Although long-term changes in environmental pollution by heavy metals have been well established in parts of China(Zeng and Wu,2009;Tang et al.,2010;Yuan et al.,2011),little information is available on temporal trends in atmospheric heavy metal deposition(Han et al.,2007;Wang et al.,2010).

The Tianshan Mountains lie in Central Asia and extend over Xinjiang,China,Kazakhstan,and Kirghizstan,with a total length of 2500km,running east-west and a width ranging from250km to

*Corresponding author.

E-mail address:w.jinglu@https://www.360docs.net/doc/1d13701116.html,(J.

Wu).

Contents lists available at ScienceDirect Quaternary International

journal h omepage:w

https://www.360docs.net/doc/1d13701116.html,/locate/quaint

1040-6182/$e see front matteró2013Elsevier Ltd and INQUA.All rights reserved.

https://www.360docs.net/doc/1d13701116.html,/10.1016/j.quaint.2013.09.047

Quaternary International321(2014)125e131

400km(Hu et al.,1996).Lake Sayram is an alpine lake in the center of the Tianshan Mountains,and is the largest deep lake in China. Human activities around Lake Sayram are very limited.Therefore, sediments in Lake Sayram are important archives of information about past atmospheric contaminant transport.Historical pollution data are useful for understanding the impact of economic devel-opment on the remote high-mountain environment of Lake Sayram.The present study has three objectives:(1)examine the stratigraphic distribution of potentially harmful elements(Cr,Cu, Pb,Cd,Zn,As and Hg)in the sediment of Lake Sayram;(2)elucidate potential input sources of heavy metals;and(3)quantify the contribution of human activities to heavy metals in the sediment.

2.Study site

Lake Sayram(44 300to44 420N,81 050to81 150E)is located near Bole City,in the eastern part of Xinjiang,China.The Lake Sayram basin is a closed,terminal alpine area surrounded by high mountains,including the Kusunmuqieke,Keguqin,Shaliqieke,and Hanziga Mountains(Wang and Dou,1998).The lake has a surface area of453km2,a catchment of1408km2,an elevation of2072m above sea level,a salinity of2.85g/L,a pH of8.8,and a maximum depth of99.0m(Wu et al.,2012).The mean annual temperature is about0.5 C,with a maximum of28.5 C in July and a minimum ofà20.9 C in January.Climate near Lake Sayram is characterized by cold winters,moderately warm summers,and arid conditions. Mean annual precipitation is350mm,which is fairly evenly distributed throughout the year.The prevailing wind is predomi-nantly from the east in winter and west or northwest in summer,as a consequence of the interaction of Mongolian-Siberian high pressures and Indian low https://www.360docs.net/doc/1d13701116.html,ke Sayram’s hydrologic input comes mainly from runoff.The longest river that?ows into the lake is the Sagakele River,18km long(Wang and Dou,1998).3.Materials and methods

3.1.Field sampling

A30-cm-long core was taken from Lake Sayram using a gravity corer in September2010.The selected sampling site was in the deepest area of the lake(Fig.1).The sediment core was used to study past information about the lake environment,the impact of human activities and regional climate changes.On extrusion, sediment in contact with the walls of the core barrel was discarded. The sediment pro?le was sectioned on a plastic sheet at intervals of 0.5cm(Wu et al.,2002).Samples for analysis of heavy metals were freeze-dried in the laboratory before analysis.

https://www.360docs.net/doc/1d13701116.html,boratory analyses

The elements Al,Cr,Cu,Pb,and Zn were determined using American Leeman Labs Pro?le Inductively Coupled Plasma-Atomic Emission Spectrometer(ICP-AES),after digestion with nitric-hydro?uoric-perchloric acid.Standard solution SPEXTM from the US was used as the standard.Quality control was assured by the analysis of duplicate samples,blanks and reference materials(GSD-9and GSD-11,Chinese geological reference materials).The con-centration of As and Cd in solution was determined by ICP-MS. Measurement errors were<10%.A Direct Mercury Analyzer(Hy-dra-C type)(Teledyne Leeman Labs,US)was used to determine Hg concentration as per US EPA(1998).Standard material ESS-3was used to control measurement quality,and the measurement errors were<2.7%.Lead isotope analyses were conducted using a Perkin e Elmer ICP-QMS SCIEX Elan9000(Renberg et al.,2002;Hu et al., 2011).Precision and accuracy were veri?ed using standard refer-ence material from the National Institute of Standards

and

Fig.1.Location of study area and sampling sites.

H.Zeng et al./Quaternary International321(2014)125e131

126

Technology(SRM981common lead isotopic material).The stan-dard values were generally within5%.

The core was dated using210Pb.Activities of210Pb and226Ra were measured using an Ortec HPGe GWL series well-type coaxial low-background intrinsic germanium detector after samples were dried at low temperature(<40 C)and weighed.Excess210Pb (210Pbex)in each sample was obtained by subtracting the activity of

226Ra from the total activity of210Pb(210Pb

tot).Then 210Pbexc was

used to develop a chronology using the constant rate of supply (CRS)dating model(Appleby and Old?eld,1978).

4.Results

4.1.Sediment dating

Vertical distributions of210Pb and137Cs activity in the sediment core are shown in Fig.2A.The210Pbex activity in the core declined from>2047Bq/kg at the core surface to near zero at about22cm (Fig.2A).Excess210Pb activity exhibited an approximately expo-nential decrease with depth,con?rming the absence of bio-turbation in these sediments.The calculated date for the22cm horizon was1880AD.Fig.2B shows the results of the CRS dating model for210Pb and137Cs peaks.The210Pb dates are in good agreement with the137Cs dates.For example,at12cm depth,where the?rst detection of137Cs activity is assumed to correspond to AD 1952(Benoit and Rozan,2001),the CRS model yielded a date of AD 1955.137Cs activity showed a peak at7.5cm,recording the1963 fallout maximum from atmospheric testing of nuclear weapons.At 9.5cm,the CRS model yielded a date of AD1968.Agreement be-tween the two dating approaches suggests that the CRS model was suitable for this core.

4.2.Heavy metal concentrations

Concentrations and natural background values of potentially harmful metals in Lake Sayram sediments are presented in Fig.3. Heavy metals are de?ned as metallic elements that have a relatively high density compared to water.Assuming that“heaviness”and toxicity are related,heavy metals also include metalloids such as arsenic,which can induce toxicity at low levels of exposure(Duffus, 2002).The concentrations of Cr,Cu,Zn,Al,As,Cd,Hg and Pb in the core were in the range of33.0e48.0mg/kg,17.4e28.9mg/kg,53.0e 83.0mg/kg,30.9e43.7g/kg, 5.7e26.8mg/kg,0.16e0.46mg/kg, 0.029e0.087mg/kg,and14.7e32.1mg/kg,respectively,with the mean concentrations of39.0mg/kg(Cr),21.4mg/kg(Cu),65.2mg/ kg(Zn),38.1g/kg(Al),9.4mg/kg(As),0.25mg/kg(Cd),0.054mg/kg (Hg)and19.7mg/kg(Pb).206Pb/207Pb values range from1.175to 1.186,with a mean value of1.183.

The vertical pro?le of heavy metal concentrations along the30-cm sediment core(Fig.3)shows the following characteristics:

(1)Concentrations of Al,Zn,Cr and Cu were fairly constant in

deeper sediments(11e30cm),but increased from10cm depth to the core top;

(2)Concentrations of Cd,As and Pb were constant below18cm,

but displayed a steady increasing trend from17cm depth and a sharp increase from5cm upward.Maximum con-centrations of the three elements were generally obtained in the topmost sediment layers;

(3)Concentrations of Hg were constant below20cm,increased

gradually from19cm to5cm depth and remained constant in the top5cm;

(4)Values of206Pb/207Pb were constant below11cm,but

showed a sharp increase between10cm and4cm,and remained constant in the top3cm.

5.Discussion

5.1.History and sources of heavy metal pollution

Trace metals in aquatic sediments are derived from both at-mospheric deposition and weathering of bedrock and soils within the catchment.Thus,simple concentration data are insuf?cient to quantify anthropogenic contamination in sediments.To distinguish natural from anthropogenic inputs,it is useful to calculate the non-dimensional enrichment factor(EF)by normalizing the

metal

Fig.2.Age model for the Lake Sayram core.A:137Cs,total210Pb and226Ra activity versus depth in the Lake Sayram sediment core.B:Age-depth relation based on210Pb and137Cs dating.

H.Zeng et al./Quaternary International321(2014)125e131127

concentrations to Al,because Al is an inert element and in the course of weathering its concentration decreases linearly with increasing sediment grain size (Din,1992).The EFs of heavy metals in the Lake Sayram sediment were calculated according to Eq.(1)(Abrahim and Parker,2008):

EF ?eM =Al TS =eM =Al TB

(1)

where,(M/Al)S is the ratio of heavy metals to Al concentrations in the samples and (M/Al)B is that in the baseline,predisturbance deposits.

The geoaccumulation index (Igeo)was employed to evaluate the pollution intensity of each heavy metal in the lake sediment,which was calculated according to Eq.(2)(Stéphane et al.,2004):

Igeo ?log 2eC n =1:5B n T(2)

where,C n is the concentration of heavy metals measured in the sediment and B n is their baseline,predisturbance deposits.

Some researchers select metal concentrations in the deeper part of the pro ?le,which are thought to have been free from anthro-pogenic in ?uences,as the “natural ”metal values (Stéphane et al.,2004;Han et al.,2007).We used metal concentrations in sedi-ments from 21to 30cm depth (i.e.pre-1900)as the reference material and their average concentrations of respective heavy metals as background values (Fig.3).The EFs and Igeos of Cr,Cu and Zn were equal or close to values of 1.0and 0.0,respectively,indi-cating that the sediments were unpolluted or only moderately polluted by these heavy metals because of human activities.In contrast,the maximum Igeos and EFs of Hg,Cd,As and Pb were >1.0and 1.5,respectively,suggesting that these heavy metals were from anthropogenic activities (Fig.4).

Using the program ZONE 1.2,the constrained incremental sum of squares cluster analysis (CONISS)was used to identify statisti-cally different zones in the sediment core (Ma et al.,2013).CONISS analysis of element concentrations and other sediment data enabled division of the Lake Sayram core into three zones,which re ?ected three distinct environmental periods (Fig.3).Results were consistent with respect to variation of EFs and Igeos of Cd,As and Pb (Fig.4).Before the 1960s,the values of EFs were approximately equal to 1and the values of Igeos were <0.5for each heavy metal,indicating limited anthropogenic in ?uence.From the 1960s to 1990s,the EFs and Igeos of Cd varied from 1.16to 1.30and 0.13to 0.48,respectively.Values for As varied from 0.97to 1.69and 0.52to 1.12.Similar values of Pb varied from 1.01to 1.20and 0.38to 0.66.

Cd,As and Pb in the sediment increased slowly between the 1960s and 1990s,demonstrating the effect of increasing human activities with economic development.Since the 1990s,the EFs of Cd,As and Pb increased from 1.48to 1.93,1.79to 3.20,and 1.24to 1.52,respectively.The values of Igeos increased from 0.81to 1.20,1.45to 2.26,and 0.92to 1.19,respectively.The EFs and Igeos of these heavy metals have increased rapidly,with their maximum values in 2010.Exhaust emission volume (EEV)in Xinjiang from 1950to 2010shows a trend similar to Gross Domestic Product (GDP)of the same period (Fig.5).It increased slowly from 1950to 1990,but sharply thereafter,especially after 2000.From 1990to 2010,the EEV increased from 1200to 9000(108m 3).Dust from exhaust emissions has high concentrations of heavy metals such as Hg and Pb (Wei et al.,2009).Therefore,the history of heavy metal pollution in Lake Sayram sediment varied consistently with economic devel-opment and associated waste discharge in Xinjiang.The EFs and Igeos of Hg increased from the 1910s and reached maximum values in the 1980s,after which they remained at relative high and con-stant levels.That this did not happen with other heavy metals is not easy to explain,but may be associated with wartime production and oil exploitation.

Total concentrations and chemical/mineralogical composition of Pb is not suf ?cient for valuation of contamination sources.Lead isotopes have been used to “?ngerprint ”environmental pollution.Each source of Pb can have distinct or overlapping ranges of isotopic ratios.The isotopic composition of Pb in lake sediments re ?ects the mixing of these sources,and source apportionment can be quan-ti ?ed if all potential sources of Pb are characterized and have spe-ci ?c ratios (Renberg et al.,2002;Michael et al.,2008).We plotted 206

Pb/207Pb against 208Pb/206Pb to provide insight into the potential sources of pollution to the sediments of Lake Sayram (Fig.3).The 206

Pb/207Pb and 208Pb/206Pb ratio pro ?les show minor ?uctuations (1.188e 1.175and 2.078e 2.091,respectively)from the base of the sequence to the topmost sediments.The 208Pb/206Pb ratio increases gradually up to the maximum value of 2.091,while the 206Pb/207Pb ratio decreases to 1.175,the lowest value in the entire sediment record.Since the 1960s,the values of 206Pb/207Pb and 208Pb/206Pb have changed,suggesting the sources of Pb have changed.

Many records of atmospheric Pb from marine/lacustrine sedi-ments,soils,peat bogs,as well as polar ice and snow have indicated varying sources and ?uxes associated with leaded gasoline,coal combustion,industrial activities (e.g.,metallurgy)and waste incineration (Michael et al.,2008).Tan et al.(2006)reported that the average Pb isotope ratios in leaded gasoline were 1.174for 206

Pb/207Pb and 2.124for 208Pb/206Pb in China,values in coal

dust

Fig.3.Vertical pro ?les of heavy metal concentrations in Lake Sayram sediment core with CONISS results.

H.Zeng et al./Quaternary International 321(2014)125e 131

128

were 1.163and 2.111respectively,and that in metallurgic dust were 1.173and 2.077.Fig.4showed the 206Pb/207Pb and 208Pb/206Pb ratio pro ?les in the Lake Sayram sediment core.After the 1990s,the 206

Pb/207Pb and 208Pb/206Pb values fell near the end-members of coal combustion,gasoline and vehicular Pb,rather than metallurgic dust (Fig.6).Therefore,coal combustion,gasoline and vehicular Pb were the primary sources of Pb contamination in the sediment cores,whereas metallurgic dust probably did not contribute much to Pb contamination.Bole,one of the major cities in Xinjiang,is about 100km from Lake Sayram.With rapid economic develop-ment and energy consumption increasing since the 1990s,by 2011discharges of waste gas and dust increased to 987.6(108m 3)and 6192.4t,respectively (Environmental Protection Bureau of Bole,2011).Exhaust gas and dust transported into the Tianshan Moun-tains and enter the Lake Sayram area via the west winds from Alshankou,a famous gale passage.The heavy metals they carry are then partly deposited in Lake Sayram,where their concentrations record changes in regional human activities.

5.2.Historic changes in natural and anthropogenic heavy metal deposition

Taking Al concentration as an indicator of background metal values supplied by weathering,the natural component of heavy metal input can be calculated (Din,1992;Ma et al.,2013):

?M natural ??Al sample ??M =?Al Background

(3)

This calculation provides an estimate of the natural inputs of heavy metals mainly from erosion of soils into the lake sediments.Subtracting the natural component of heavy metals from the total concentrations yields the excess,anthropogenic concentration of heavy metals supplied to the lake sediment via atmospheric deposition.That component is calculated as follows:

?M anthropogenic ??M total à?M natural

(4)

The natural or anthropogenic heavy metal concentrations are converted to accumulation rates (NAF or AAF)(mg/cm 2/a or)as follows:

?M Flux natural =anthropogenic ??M natural =anthropogenic ?R ?r

(5)

where R is sedimentation rate and r is dry bulk density of the sediment.

In the last 200years,the natural accumulation ?ux (NAF)of As varied from 0.20to 0.42m g/cm 2/y with a mean value of 0.29.The anthropogenic accumulation ?ux (AAF)of As varied from 0.00to 0.98m g/cm 2/y,with a mean value of 0.11.The NAF of Cd varied from 5.89to 12.53ng/cm 2/y,with a mean value of 8.67.The AAF of Cd varied from 0.00to 7.30ng/cm 2/y,with a mean value of 1.44.The NAF of Pb varied from 1.13to 2.41m g/cm 2/y with a mean value of 1.67.The AAF of Pb varied from 0.00to 0.39m g/cm 2/y,with a mean value of 0.09.The NAF of Hg varied from 0.48to 1.03ng/cm 2/y,with a mean value of 0.71.The AAF of Hg varied from 0.00to 1.98ng/cm 2/y,with a mean value of 0.59(Fig.7).

From the 1960s to 2010,there was an increasing trend in AAFs of Pb,Cd,As and Hg (Fig.7).A dramatic increase in anthropogenic Pb deposition since the 1960s is consistent with the regional/global trend in Pb emissions to the atmosphere (Nriagu,1989;Weiss et al.,1999).During 1990e 2010,AAFs of Cd,As,Pb and Hg increased from 4.05to 7.30ng/cm 2/y,0.27e 0.98m g/cm 2/y,0.21e 0.39m g/cm 2/y,and 0.61e 0.83ng/cm 2/y,respectively.Anthropogenic accumulation ?uxes contributed 45.5%(mean value)of As,33.3%of Cd,21.9%of Pb and 41.5%of Hg,to the total mass accumulation ?uxes of those heavy metals.The maximal contribution ratios were 68.8%for

As,

Fig.4.Depth pro ?les for Igeos and EFs of heavy metals in Lake Sayram sediment

core.

Fig.5.Temporal trends of GDP and EEV in Xinjiang Province from 1950to

2010.Fig.6.The

206

Pb/207Pb and

208

Pb/206Pb ratio pro ?les in Lake Sayram sediment core.

H.Zeng et al./Quaternary International 321(2014)125e 131129

48.1%for Cd,34.4%for Pb and 37.0%for Hg in the 1990s,when heavy metal contamination was at its highest level.This ?ux is compa-rable to values reported in other places throughout China and Europe.From 1860to 2002,an increase in total Hg ?ux was observed (0.5e 3.2ng/cm 2/a)at Qinghai Lake on the Tibetan Plateau (Wang et al.,2010).Fluxes of Pb and Hg were 0.1e 0.4m g/cm 2/y and 0.19e 0.75ng/cm 2/y in Lake Lucerne,located at the northern Alpine front in central Switzerland (Thevenon et al.,2011a ).The results suggest that the ?uxes of heavy metals and contamination in Lake Sayram are higher than those in alpine environments,but are lower than those found at Qinghai Lake.This may be explained by the fact that Qinghai Lake is geographically closer to industrialized prov-inces than is Lake Sayram (Jin et al.,2010).6.Conclusions

Concentrations,EFs and Igeos of heavy metals in a sediment core from Lake Sayram indicated that Cr,Cu and Zn in the sediment was mainly from natural sources,whereas Cd,Pb,As and Hg were increased signi ?cantly since the 1960s as a consequence of anthropogenic https://www.360docs.net/doc/1d13701116.html,ke Sayram is today considered to be moderately polluted by Cd,Hg,and Pb,and moderately to highly polluted by As.The anthropogenic contamination of heavy metals in Lake Sayram sediment was quanti ?ed by anthropogenic accu-mulation ?uxes (AAFs).During 1990e 2010,AAFs of Cd,As,Pb and Hg increased from 4.05to 7.30ng/cm 2/a,0.27e 0.98m g/cm 2/a,and 0.21e 0.39m g/cm 2/a and 0.61e 0.83ng/cm 2/a,respectively,re ?ect-ing the anthropogenic contribution to the heavy metal enrichment in Lake Sayram sediment.Anthropogenic heavy metal contamina-tion in Lake Sayram is greater than in an alpine lake in Europe,but lower than in Qinghai Lake,central China.Acknowledgments

We thank Longsheng Xu and Yuxing Zhu for ?eld and laboratory assistance.Thanks are also due to Mark Brenner for his helpful comments and revision of the text and the journal reviewers for their helpful comments and suggestions that improved the

manuscript.This study was supported by the National Basic Research Program of China (No.2012CB956102;2010DFA92720-22),National Natural Science Foundation of China (U113830;41101190).

References

Abrahim,G.M.S.,Parker,R.J.,2008.Assessment of heavy metal enrichment factors

and the degree of contamination in marine sediments from Tamaki Estuary,Auckland,New Zealand.Estuarine,Coastal and Shelf Science 136,227e 238.Appleby,P.,Old ?eld,F.,1978.The calculation of lead-210dates assuming a constant

rate of supply of unsupported 210Pb to the sediment.Catena 5,1e 8.

Benoit,G.,Rozan,T.F.,2001.210Pb and 137Cs dating methods in lakes:a retrospective

study.Journal of Paleolimnology 25,455e 465.

Callender,E.,Rice,K.C.,2000.The urban environmental gradient:anthropogenic

in ?uences on the spatial and temporal distributions of lead and zinc in sedi-ments.Environmental and Science and Technology 2,232e 238.

Copat,C.,Bella,F.,Castaing,M.,Fallico,R.,Sciacca,S.,Ferrante,M.,2012.Heavy

metals concentrations in ?sh from Sicily (Mediterranean Sea)and evaluation of possible health risks to consumers.Bulletin Environment Contamination and Toxicology 88,78e 83.

Dassenakis,M.,Andrianos,H.,Depiazi,G.,2003.The use of various methods for the

study of metal pollution in marine sediments,the case of Euvoikos Gulf,Greece.Applied Geochemistry 18,781e 794.

Deepulal,P.M.,Gireesh kumar,T.R.,Sujatha,C.H.,Rejomon,G.,2012.Chemometric

study on the trace metal accumulation in the sediments of the Cochin estuary-southwest coast of India.Environmental Monitoring and Assessment 184,6261e 6279.

Din,Z.,https://www.360docs.net/doc/1d13701116.html,e of aluminum to normalize heavy metals data from the estuarine

and coastal sediments of the strait of Melaka.Marine Pollution Bulletin 24,484e 491.

Duffus,J.H.,2002.Heavy metals d a meaningless term?Pure and Applied Chemistry

74,793e 807.

Environmental Protection Bureau of Bole,2011.The Bortala Autonomous Prefecture

Environmental Quality Bulletin in 2011.https://www.360docs.net/doc/1d13701116.html,/content.aspx?id ?227791690188(in Chinese).

Han,Y.,Jin,Z.,Cao,J.,Posmentier,E.S.,An,Z.,2007.Atmospheric Cu and Pb depo-sition and transport in lake sediments in a remote mountain area,Northern China.Water Air Soil Pollution 179,167e 181.

Hu,R.,Yang,C.,Ma,H.,Jiang,F.,1996.Climatic trend indicated by variations of

glaciers and lakes in the Tianshan mountains.Chinese Geographical Science 6(3),239e 246.

Hu,X.,Wang,C.,Zou,L.,2011.Characteristics of heavy metals and Pb isotopic sig-natures in sediment cores collected from typical urban shallow lakes in Nanj-ing,China.Journal of Environmental Management 92,742e 748.

Jin,Z.,Han,Y.,Chen,L.,2010.Past atmospheric Pb deposition in Lake Qinghai,

northeastern Tibetan Plateau.Journal of Paleolimnology,1e 13

.

Fig.7.Natural and anthropogenic accumulation ?uxes/percents of Pb,As,Zn and Hg in the sediment of Lake Sayram.

H.Zeng et al./Quaternary International 321(2014)125e 131

130

Ma,L.,Wu,J.,Abuduwaili,J.L.L.,2013.Geochemical evidence of the anthropogenic alteration of element composition in lacustrine sediments from Wuliangsu Lake,north China.Quaternary International306,107e113.

Michael,K.,Vojt e ch,E.E.,Vladislav,V.,Chrastny,C.,Martin,M.,2008.Lead isotopes in environmental sciences:a review.Environment International34,562e577. Nriagu,J.O.,1989.A global assessment of natural sources of atmospheric trace metals.Nature338,47e49.

Opfer,S.E.,Farver,J.R.,Jeffrey,G.,Krieger,M.K.,2011.Heavy metals in sediments and uptake by burrowing may?ies in western Lake Erie basin.Journal of Great Lakes Research37(1),1e8.

Renberg,I.,Brannvall,M.L.,Bindler,R.,Emteryd,O.,2002.Stable lead isotopes and lake sediments-a useful combination for the study of atmospheric lead pollu-tion history.Science of the Total Environment292,45e54.

Rippey,B.,Rose,N.,Yang,H.,Harrad,S.,Robson,M.,Travers,S.,2008.An assessment of toxicity in profundal lake sediment due to deposition of heavy metals and persistent organic pollutants from the atmosphere.Environment International 34,345e356.

Stéphane,A.,J?rg,S.,Gérard,B.,Jouanneau,J.M.,2004.Fifty-year sedimentary re-cord of heavy metal pollution(Cd,Zn,Cu,Pb)the Lot River reservoirs(France).

Environmental Pollution132,413e426.

Tan,M.,Zhang,G.,Li,X.,Zhang,Y.,Yue,W.,Chen,J.,Wang,Y.,Li,A.,Li,Y.,Zhang,Y., Shan,C.,https://www.360docs.net/doc/1d13701116.html,prehensive study of lead pollution in Shanghai by multiple techniques.Analytical Chemistry78(23),8044e8050.

Tang,W.,Shan,B.,Zhang,H.,Mao,Z.,2010.Heavy metal sources and associated risk in response to agricultural intensi?cation in the estuarine sediments of Chaohu Lake Valley,East China.Journal of Hazardous Materials176,945e951. Thevenon,F.,Guédron,S.,Chiaradia,M.,Loizeau,J.L.,Poté,J.,2011a.(Pre-)historic changes in natural and anthropogenic heavy metals deposition inferred from two contrasting Swiss Alpine lakes.Quaternary Science Review30,224e233. Thevenon,F.,Neil,D.,Chiaradia,G.M.,Arpagaus,P.,Wildi,W.,Poté,J.,2011b.Local to regional scale industrial heavy metal pollution recorded in sediments of large

freshwater lakes in central Europe(lakes Geneva and Lucerne)over the last centuries.Science of the Total Environment412e413,239e247.

Wang,S.,Dou,H.,1998.Memoirs of Lakes in China.Science Press,Beijing,pp.105e 177(in Chinese).

Wang,X.,Yang,H.,Gong,P.,Zhao,X.,Wu,G.,Turner,S.,Yao,T.,2010.One century sedimentary records of polycyclic aromatic hydrocarbons,mercury and trace elements in Qinghai Lake,Tibetan Plateau.Environmental Pollution158,3065e 3070.

Wei, B.,Jiang, F.,Li,X.,Mu,S.,2009.Spatial distribution and contamination assessment of heavy metals in urban road dusts from Urumqi,NW China.

Microchemistry Journal93,147e152.

Weiss,D.,Shotyk,W.,Appleby,P.G.,Kramers,J.D.,Cheburkin,A.K.,1999.Atmo-spheric Pb deposition since the industrial revolution recorded by?ve Swiss peat pro?les:enrichment factors,?uxes,isotopic composition,and sources.

Environmental Science and Technology33,1340e1352.

Wu,J.,Li,S.,Luecke,A.,Wang,S.,2002.Climatic signals in the last200years from stable isotope record in the shells of freshwater snails in Lake Xingcuo,eastern Tibet Plateau,China.Chinese Journal of Geochemistry21, 234e243.

Wu,J.,Zheng,H.,Ma,L.,Bai,R.,2012.Recent changes of selected lake water re-sources in arid Xinjiang,northwestern China32(1),142e150(in Chinese). Wu,Y.,Hou,X.,Cheng,X.,Yao,S.,Xia,W.,Wang,S.,https://www.360docs.net/doc/1d13701116.html,bining geochemical and statistical methods to distinguish anthropogenic source of metals in lacustrine sediment:a case study in Dongjiu Lake,Taihu Lake catchment,China.

Environmental Geology52(8),1467e1474.

Yuan,G.,Liu,C.,Chen,L.,Yang,Z.,2011.Inputting history of heavy metals into the inland lake recorded in sediment pro?les:Poyang Lake in China.Journal of Hazardous Materials.185,336e345.

Zeng,H.,Wu,J.,2009.Sediment records of heavy metal pollution in Fuxian Lake,Yunnan,China:the intensity,history and source.Pedosphere19(5), 562e569.

H.Zeng et al./Quaternary International321(2014)125e131131