辽河口海岸带沉积物中~(137)Cs的分布特征及来源
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摘要
选取辽河口海岸带沉积物作为研究对象,通过测定沉积物中~(137)Cs比活度,来分析沉积物中~(137)Cs比活度、蓄积总量的分布特征及影响因素,并基于~(137)Cs的测年原理估算该区域的沉积速率。结果表明:辽河口海岸带表层沉积物中~(137)Cs比活度的变化范围为(1.03±1.01)～(15.68±1.13)Bq/kg,平均值为5.09±0.34Bq/kg(n=17),变化幅度较大;在空间上呈现出由陆地向潮滩、由西向东逐渐降低的趋势。该区域沉积物柱样中~(137)Cs比活度的垂直分布主要呈现出单峰型、双峰型和不规则曲线的分布态势。采用~(137)Cs起始层位法与最大峰值法计算辽河口海岸带沉积物的沉积速率,均发现辽河口海岸带沉积物的沉积速率呈现出从北到南(从陆地到海洋)逐渐增大的趋势。沉积物中~(137)Cs蓄积总量范围为(980±46)～(6094±92)Bq/m2,平均值为2278±42Bq/m2,高于研究区~(137)Cs的全球大气沉降通量值1310Bq/m2(衰变校正到2015年);全球大气沉降的~(137)Cs约占该区域~(137)Cs蓄积总量约57.5%,表明该区域沉积物中~(137)Cs的主要来源是全球大气直接沉降。
~(137)Cs activities are measured for the 17 sediment cores collected from the coastal zones of the Liao River in order to disclose the distribution patterns and geochemical behaviors of ~(137)Cs.It is found that ~(137)Cs activity concentrations in the surface sediments vary in a significant spatial range from1.03±1.01 to 15.68±1.13 mBq/g around an average of 6.727±0.251 mBq/g(1σ)attributing to the changes in vegetation types.Highest ~(137)Cs activity concentration(15.686±1.131 mBq/g)is observed in the sediment core of Z-9 where reeds predominate natural vegetation and human activity is rare.The vertical distribution pattern of ~(137)Cs activity concentrations falls into three categories,one-peak curve,two-peak curve and irregular curve.For the two-peak curves of ~(137)Cs activity concentration,there is a sub-peak of ~(137)Cs activity concentration in the sediment profiles except the maximum of ~(137)Cs.As to the irregular curves of ~(137)Cs(LH-15,LH-18),the ~(137)Cs activity concentrations decreases from the sub-layer to the bottom and part of the surface sediment was missing,or for another possibility bottom sediment was putting on the surface layer by anthropogenic activities Sedimentation rates are calculated with the initial ~(137)Cs appearance value(1954)up to the maximum value(1963)of the sediment cores.The average value of sedimentation rates(0.48 to 1.63 cm/a)deduced from~(137)Cs maximum value seem to be lower than the rates(0.51 to 1.77 cm/a)calculated from~(137)Cs initial appearance.The ~(137)Cs inventories vary from980±46 to 6094±92 Bq/m2,with an average of2278±42 Bq/m2.Furthermore,the average ~(137)Cs inventories of the study are higher than the global fallout flux 1310 Bq/m2(~(137)Cs activity was decay corrected to 2015).This result clearly indicates that the ~(137)Cs atmospheric precipitation is the main source of ~(137)Cs in the region of Liao River Estuary.
~(137)Cs activities are measured for the 17 sediment cores collected from the coastal zones of the Liao River in order to disclose the distribution patterns and geochemical behaviors of ~(137)Cs.It is found that ~(137)Cs activity concentrations in the surface sediments vary in a significant spatial range from1.03±1.01 to 15.68±1.13 mBq/g around an average of 6.727±0.251 mBq/g(1σ)attributing to the changes in vegetation types.Highest ~(137)Cs activity concentration(15.686±1.131 mBq/g)is observed in the sediment core of Z-9 where reeds predominate natural vegetation and human activity is rare.The vertical distribution pattern of ~(137)Cs activity concentrations falls into three categories,one-peak curve,two-peak curve and irregular curve.For the two-peak curves of ~(137)Cs activity concentration,there is a sub-peak of ~(137)Cs activity concentration in the sediment profiles except the maximum of ~(137)Cs.As to the irregular curves of ~(137)Cs(LH-15,LH-18),the ~(137)Cs activity concentrations decreases from the sub-layer to the bottom and part of the surface sediment was missing,or for another possibility bottom sediment was putting on the surface layer by anthropogenic activities Sedimentation rates are calculated with the initial ~(137)Cs appearance value(1954)up to the maximum value(1963)of the sediment cores.The average value of sedimentation rates(0.48 to 1.63 cm/a)deduced from~(137)Cs maximum value seem to be lower than the rates(0.51 to 1.77 cm/a)calculated from~(137)Cs initial appearance.The ~(137)Cs inventories vary from980±46 to 6094±92 Bq/m2,with an average of2278±42 Bq/m2.Furthermore,the average ~(137)Cs inventories of the study are higher than the global fallout flux 1310 Bq/m2(~(137)Cs activity was decay corrected to 2015).This result clearly indicates that the ~(137)Cs atmospheric precipitation is the main source of ~(137)Cs in the region of Liao River Estuary.
引文
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[14]潘少明,朱大奎,李炎,等.河口港湾沉积物中的137 Cs剖面及其沉积学意义[J].沉积学报,1997,15(4):67-71.[PANShaoming,ZHUDakui,LI Yan,et al.137 Cs profile in sediments in estuaries and its application in sedimentology[J].Acta Sedimentological Sinica,1997,15(4):67-71.]
[15] Zheng J,Wu F C,Yamada M,et al.Global fallout Pu recorded in lacustrine sediments in Lake Hongfeng,SW China[J].Environmental Pollution,2008,152:314-321.
[16]张瑞.利用210Pb和137 Cs分析近五十年来长江口水下三角洲现代沉积过程对入海泥沙变化的响应[D].南京大学,2009.[ZHANG Rui.The response of morden sediment process of Changjiangestuarysubaqueousdeltatovariationof Changjiang Riversediment fluxes elucidated from nuclides210Pb and 137Cs[D].Nanjing University,2009.]
[17]王福,王宏,李建芬,等.渤海地区210 Pb、137 Cs同位素测年的研究现状[J].地质论评,2006,52(2):244-250.[WANG Fu,WANG Hong,LI Jianfen,et al.Current study of 210Pb and 137Cs geochronology in the Circum-Bohai Sea region[J].Geological Review,2006,52(2):244-250.]
[18]刘志勇.长江口及苏北潮滩沉积物中放射性核素钚的分布特征与环境意义[D].南京大学,2011.[LIUZhiyong.Pu and137Cs in the Yangtze River estuary sediments:distribution and source identification[D].Nanjing University.Nanjing,2011.]
[19] Hancock G J,Leslie C,Everett S E,et al.Plutonium as a chronomaker in Australian and New Zealand sediments:a comparison with 137Cs[J].Journal of Environmental Radioactivity,2011,102:919-929.
[20]曹立国,潘少明,刘旭英,等.长江口水下三角洲239,240 Pu和137Cs的分布特征及环境意义[J].地理科学,2014,34(1):97-102.[CAOLiguo,PANShaoming,LIUXuying,et al.Distribution characteristics of 239,240Pu and 137Cs in subaqueous delta at the Changjiang River Estuary and the environmental significance[J].Scientia Geographica Sinica,2014,34(1):97-102.]
[21] Sutherland R A,De Jong E.Estimation of sediment redistribution within agricultural fields using Caesium-137,Crystal Springs,Saskatchewan,Canada[J].Applied Geography,1990,10(3):205-221.
[22]王颖,朱大奎.中国的潮滩[J].第四纪研究,1990,10(4):291-300.[WANG Ying,ZHU Dakui.Tidal flats of China[J].Quaternary Sciences,1990,10(4):291-300.]
[23] Ritchie J C,McHenry J R.A comparison of three methods for measuring recent rates of sediment accumulation[J].Water Resources Bulletin,1985,21(1):99-103.
[24]张信宝,曾奕,龙翼.137Cs质量平衡法测算青海湖现代沉积速率的尝试[J].湖泊科学,2009,21(6):827-833.[ZHANG Xinbao,ZENG Yi,LONG Yi.An attempt to use the 137Cs mass balance model for assessment of recent deposition rates in Lake Qinghai,China[J].Journal Lake Science,2009,21(6):827-833.]
[25]项亮.137Cs湖泊沉积年代学方法应用的局限—Crawford湖为例[J].湖泊科学,1995,7(4):307-313.[XIANG Liang.Limitations of the application of 137Cs limnochronology:A case study of 137Cs profile in crawford lake sediment[J].Journal Lake Science,1995,7(4):307-313.]
[26]符荣初,王惠玉.切尔诺贝利核电站事故后苏州市环境介质中134,137Cs含量变化和剂量评价[J].中国核科技报告,1994(4):263-265.[FURongchu,WANGHuiyu.Changes of and dose134,137Cs evaluation in environmental media in Suzhou after Chernobyl[J].Nuclear Technology Report in China,1994(4):263-265.]
[27] Huh C A,Su C C.Sedimentation dynamics in the East China Sea elucidated from210Pb,137Cs and 239+240Pu[J].Marine Geology,1999,160(1):183-196.
[28] Su C C,Huh C A.210Pb,137Cs and 239+240Pu in East China Sea sediments:sources,pathways and budgets of sediments and radionuclides[J].Marine Geology,2002,183(s1-4):163-178.
[29]李建芬,王宏,夏威岚,等.渤海湾西岸210 Pbexc、137 Cs测年与现代沉积速率[J].地质调查与研究,2003,26(2):114-128.[LI Jianfen,WANG Hong,XIA Weilan,et al.210Pbexc and 137Cs dating and modern sedimentation rate on the western coast of Bohai Bay[J].Geological Survey and Research,2003,26(2):114-128.]
[30] Schaffner L C,Diaz R J,Olsen C R,et al.Faunal characteristics and sediment accumulation processes in the James River estuary,Virginia[J].Estuarine Coastal&Shelf Science,1987,25(2):211-226.
[31]宋云香,战秀文,王玉广.辽东湾北部河口区现代沉积特征[J].海洋学报,1997(5):145-149.[SONG Yunxiang,ZHAN Xiuwen,WANG Yuguang.The mineral character and substance sources of coastal sediment in the Liaodong Bay[J].Marine Science Bulletin,1997(5):145-149.]
[32]杨松林,刘国贤,杜瑞芝,等.用210Pb年代学方法对辽东湾现代沉积速率的研究[J].沉积学报,1993,11(1):128-135.[YANG Songlin,LIU Guoxian,DU Ruizhi,et al.Study on the modern sedimentation rate through 210Pb age dating,Liaodong Bay[J].Acta Sedimentological Sinica,1993,11(1):128-135.]
[33]曹立国,潘少明,何坚,等.辽东湾地区137 Cs大气沉降研究[J].环境科学学报,2015,35(1):80-86.[CAO Liguo,PAN Shaoming,HE Jian,et al.137Cs atmospheric deposition in the Liaodong Bay[J].Journal of Environmental Sciences,2015,25(1):80-86.]
[34]刘晓曼,王桥,庄大方,等.湿地变化对双台河口自然保护区服务功能的影响[J].中国环境科学,2013,12:2208-2214.[LIU Xiaoman,WANG Qiao,ZHUANG Dafang,et al.Impacts of wetland change on ecosystem services value of Shuangtaihekou Nature Reserve[J].China Environmental Science,2013,12:2208-2214.]
[2]刘存岐.河口潮滩湿地沉积物中胞外酶研究[D].华东师范大学,2003.[LIU Congqi.Study on extracellular enzymes in sediments of estuarine tidal flats[D].East China Normal University,2003.]
[3]陈军,付军,盛辉,等.海岸带环境遥感原理与应用[M].海洋出版社,2013.[CHEN Jun,FU Jun,SHENG Hui,et al.Remote Sensing Principle and Application of Coastal Zone Environment[M].Beijing:Ocean Press,2013.]
[4] Abdi M R,Hassanzadeh S,Kamali M,et al.238 U,232 Th,40 K and137 Cs activity concentrations along the southern coast of the Caspian Sea,Iran[J].Marine Pollution Bulletin,2009,58(5):658-662.
[5]万国江.现代沉积年分辨的137 Cs计年——以云南洱海和贵州红枫湖为例[J].第四纪研究,1999,19(1):73-80.[WANG Guojiang.137Cs dating by annual distinguish for recent sedimentation:samples from Erhai Lake and HongfengLake[J].Quaternary Sciences.1999,19(1):73-80.]
[6] Chen J Y,Li D,Chen S.Progress of estuarine in China over50years[J].Science in China,2001,44(S1):1-9.
[7] Baskaran M,Naidu A S.210Pb-derived chronology and the fluxes of 210Pb and 137Cs isotopes into continental shelf sediments,east Chukchi Sea,Alaskan Arctic[J].GeochimicaetCosmochimicaActa,1995,59(21):4435-4448.
[8] Liu Z Y,Pan S M,Liu X Y,et al.Distribution of 137Cs and210Pb in sediments of tidal flats in north Jiangsu province[J].Journal of Geographical Sciences.2010,20(1):91-108.
[9] Pan S M,Tims S G,Liu X Y,et al.137Cs,239,240Pu concentrations and the 240Pu/239Pu atom ratio in a sediment core from the sub-aqueous delta of Yangtze River estuary[J].Journal of Environmental Radioactivity,2011,102:930-936.
[10] Robbins J A,Edgington D N.Determination of recent sedimentation rates in Lake Michigan using 210Pb and 137Cs[J].Geochimicaet Cosmochimica Acta,1975,39:285-304.
[11] Smith J N,Walton A.Sediment accumulation rates and geochronologies measured in the Saguenay Fjord using the Pb-210dating method[J].Geochimicaet Cosmochimica Acta,1980,44(2):225-240.
[12] DeMaster D J,McKee B A,Nittrouer C A,et al.Rates of sedimentreworking at the Hebble site based on measurements of 234 Th,137Cs and 210Pb[J].Marine Geology,1985,66:133-148.
[13]万国江,林文祝,黄荣贵,等.红枫湖沉积物137 Cs垂直剖面的计年特征及侵蚀示踪[J].科学通报,1990,19:1487-1490.[WANG Guojiang,LIN WenZhu,HUANG Ronggui,et al.Distribution characteristics and source of 137Cs in the sediment cores from the Liao river estuary[J].Chinese Science Bulletin,1990,19:1487-1490.]
[14]潘少明,朱大奎,李炎,等.河口港湾沉积物中的137 Cs剖面及其沉积学意义[J].沉积学报,1997,15(4):67-71.[PANShaoming,ZHUDakui,LI Yan,et al.137 Cs profile in sediments in estuaries and its application in sedimentology[J].Acta Sedimentological Sinica,1997,15(4):67-71.]
[15] Zheng J,Wu F C,Yamada M,et al.Global fallout Pu recorded in lacustrine sediments in Lake Hongfeng,SW China[J].Environmental Pollution,2008,152:314-321.
[16]张瑞.利用210Pb和137 Cs分析近五十年来长江口水下三角洲现代沉积过程对入海泥沙变化的响应[D].南京大学,2009.[ZHANG Rui.The response of morden sediment process of Changjiangestuarysubaqueousdeltatovariationof Changjiang Riversediment fluxes elucidated from nuclides210Pb and 137Cs[D].Nanjing University,2009.]
[17]王福,王宏,李建芬,等.渤海地区210 Pb、137 Cs同位素测年的研究现状[J].地质论评,2006,52(2):244-250.[WANG Fu,WANG Hong,LI Jianfen,et al.Current study of 210Pb and 137Cs geochronology in the Circum-Bohai Sea region[J].Geological Review,2006,52(2):244-250.]
[18]刘志勇.长江口及苏北潮滩沉积物中放射性核素钚的分布特征与环境意义[D].南京大学,2011.[LIUZhiyong.Pu and137Cs in the Yangtze River estuary sediments:distribution and source identification[D].Nanjing University.Nanjing,2011.]
[19] Hancock G J,Leslie C,Everett S E,et al.Plutonium as a chronomaker in Australian and New Zealand sediments:a comparison with 137Cs[J].Journal of Environmental Radioactivity,2011,102:919-929.
[20]曹立国,潘少明,刘旭英,等.长江口水下三角洲239,240 Pu和137Cs的分布特征及环境意义[J].地理科学,2014,34(1):97-102.[CAOLiguo,PANShaoming,LIUXuying,et al.Distribution characteristics of 239,240Pu and 137Cs in subaqueous delta at the Changjiang River Estuary and the environmental significance[J].Scientia Geographica Sinica,2014,34(1):97-102.]
[21] Sutherland R A,De Jong E.Estimation of sediment redistribution within agricultural fields using Caesium-137,Crystal Springs,Saskatchewan,Canada[J].Applied Geography,1990,10(3):205-221.
[22]王颖,朱大奎.中国的潮滩[J].第四纪研究,1990,10(4):291-300.[WANG Ying,ZHU Dakui.Tidal flats of China[J].Quaternary Sciences,1990,10(4):291-300.]
[23] Ritchie J C,McHenry J R.A comparison of three methods for measuring recent rates of sediment accumulation[J].Water Resources Bulletin,1985,21(1):99-103.
[24]张信宝,曾奕,龙翼.137Cs质量平衡法测算青海湖现代沉积速率的尝试[J].湖泊科学,2009,21(6):827-833.[ZHANG Xinbao,ZENG Yi,LONG Yi.An attempt to use the 137Cs mass balance model for assessment of recent deposition rates in Lake Qinghai,China[J].Journal Lake Science,2009,21(6):827-833.]
[25]项亮.137Cs湖泊沉积年代学方法应用的局限—Crawford湖为例[J].湖泊科学,1995,7(4):307-313.[XIANG Liang.Limitations of the application of 137Cs limnochronology:A case study of 137Cs profile in crawford lake sediment[J].Journal Lake Science,1995,7(4):307-313.]
[26]符荣初,王惠玉.切尔诺贝利核电站事故后苏州市环境介质中134,137Cs含量变化和剂量评价[J].中国核科技报告,1994(4):263-265.[FURongchu,WANGHuiyu.Changes of and dose134,137Cs evaluation in environmental media in Suzhou after Chernobyl[J].Nuclear Technology Report in China,1994(4):263-265.]
[27] Huh C A,Su C C.Sedimentation dynamics in the East China Sea elucidated from210Pb,137Cs and 239+240Pu[J].Marine Geology,1999,160(1):183-196.
[28] Su C C,Huh C A.210Pb,137Cs and 239+240Pu in East China Sea sediments:sources,pathways and budgets of sediments and radionuclides[J].Marine Geology,2002,183(s1-4):163-178.
[29]李建芬,王宏,夏威岚,等.渤海湾西岸210 Pbexc、137 Cs测年与现代沉积速率[J].地质调查与研究,2003,26(2):114-128.[LI Jianfen,WANG Hong,XIA Weilan,et al.210Pbexc and 137Cs dating and modern sedimentation rate on the western coast of Bohai Bay[J].Geological Survey and Research,2003,26(2):114-128.]
[30] Schaffner L C,Diaz R J,Olsen C R,et al.Faunal characteristics and sediment accumulation processes in the James River estuary,Virginia[J].Estuarine Coastal&Shelf Science,1987,25(2):211-226.
[31]宋云香,战秀文,王玉广.辽东湾北部河口区现代沉积特征[J].海洋学报,1997(5):145-149.[SONG Yunxiang,ZHAN Xiuwen,WANG Yuguang.The mineral character and substance sources of coastal sediment in the Liaodong Bay[J].Marine Science Bulletin,1997(5):145-149.]
[32]杨松林,刘国贤,杜瑞芝,等.用210Pb年代学方法对辽东湾现代沉积速率的研究[J].沉积学报,1993,11(1):128-135.[YANG Songlin,LIU Guoxian,DU Ruizhi,et al.Study on the modern sedimentation rate through 210Pb age dating,Liaodong Bay[J].Acta Sedimentological Sinica,1993,11(1):128-135.]
[33]曹立国,潘少明,何坚,等.辽东湾地区137 Cs大气沉降研究[J].环境科学学报,2015,35(1):80-86.[CAO Liguo,PAN Shaoming,HE Jian,et al.137Cs atmospheric deposition in the Liaodong Bay[J].Journal of Environmental Sciences,2015,25(1):80-86.]
[34]刘晓曼,王桥,庄大方,等.湿地变化对双台河口自然保护区服务功能的影响[J].中国环境科学,2013,12:2208-2214.[LIU Xiaoman,WANG Qiao,ZHUANG Dafang,et al.Impacts of wetland change on ecosystem services value of Shuangtaihekou Nature Reserve[J].China Environmental Science,2013,12:2208-2214.]
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