巢湖沉积物δ~(13)C_(org)和δ~(15)N记录的生态环境演化过程
摘要
通过对巢湖2处柱状沉积物样品中δ13Corg、δ15N、C/N比值、TOC和TN含量的测定,分析了近百年来巢湖沉积物有机质的来源,探讨受人类活动影响的湖泊生产力变化和富营养化过程.结果表明,巢湖沉积物有机质的主要来源是水生藻类,陆生有机质的输入量较少,但是城市污染物的输入与农业面源污染的影响是不可忽视的.巢湖沉积物剖面上,δ13Corg、δ15N、TOC和TN含量变化按沉积深度可以明显划分为2个阶段:①10 cm以下,H3点δ13Corg波动在-21.74‰~-19.34‰的范围内,其余数据表现相对平缓,湖泊内的生物物种是固氮植物和非固氮植物共存,2个采样点具有不同的湖泊营养化进程;②10 cm至表层段,2个剖面的δ13Corg迅速减小,δ15N、TOC和TN则是显著增大,巢湖闸的建成使得内源营养物质快速积累,湖泊初始生产力水平迅速提高,富营养化加剧.
Variations of δ~(13)C_(org) and δ~(15)N values, C/N ratios,TOC and TN contents in Chaohu Lake sediments reflect the sources of organic matter in lake sediments,evolution of lake productivity and the eutrophic status in Chaohu Lake during last 100 years.Our results suggest that the sedimentary organic matter was derived mainly from aquatic algae and partly from land matter.However,the input of the pollutants from city and agriculture into the lake could not be neglected.Two stages can be found in the sediments cores according to the profiles of δ~(13)C_(org),δ~(15)N values,TOC and TN contents.Below 10cm,δ~(13)C_(org) values vary between-21.74‰ and-19.34‰.Nitrogen fixing and non-nitrogen fixing phytoplankton coexist together.Two cores show different nutrition processes.Above 10cm,in both profiles,the values of δ~(13)C_(org) start to decrease sharply,but δ~(15)N, TOC and TN increase.The construction of Chaohu Gate leads to the enhancement of lake productivity and development of eutrophication.
Variations of δ~(13)C_(org) and δ~(15)N values, C/N ratios,TOC and TN contents in Chaohu Lake sediments reflect the sources of organic matter in lake sediments,evolution of lake productivity and the eutrophic status in Chaohu Lake during last 100 years.Our results suggest that the sedimentary organic matter was derived mainly from aquatic algae and partly from land matter.However,the input of the pollutants from city and agriculture into the lake could not be neglected.Two stages can be found in the sediments cores according to the profiles of δ~(13)C_(org),δ~(15)N values,TOC and TN contents.Below 10cm,δ~(13)C_(org) values vary between-21.74‰ and-19.34‰.Nitrogen fixing and non-nitrogen fixing phytoplankton coexist together.Two cores show different nutrition processes.Above 10cm,in both profiles,the values of δ~(13)C_(org) start to decrease sharply,but δ~(15)N, TOC and TN increase.The construction of Chaohu Gate leads to the enhancement of lake productivity and development of eutrophication.
引文
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[22]Maren V,Birger L,Mirja L,et al.Stable isotope signals ofeutrophication in Baltic Sea sediments[J].Journal of MarineSystems,2000,25:287~298.
[2]李素菊,吴倩,王学军,等.巢湖浮游植物叶绿素含量与反射光谱特征的关系[J].湖泊科学,2002,14(3):228~234.
[3]陈慧,王进.巢湖富营养化危害及控制对策[J].合肥工业大学学报,1999,22(S1):63~66.
[4]王永华,钱少猛,徐南妮,等.巢湖东区底泥污染物分布特征及评价[J].环境科学研究,2004,17(6):22~26.
[5]姚书春,李世杰.巢湖富营养化过程的沉积记录[J].沉积学报,2004,22(2):343~347.
[6]张崇岱,潘宝林.巢湖湖盆及其变迁研究[J].安徽师范大学学报,1990,13(1):48~56.
[7]Wu J L,Michael K,Gagan,et al.Sedimentary geochemicalevidence for recent eutrophication of Lake Chenghai,Yunnan,China[J].Journal of Paleolimnology,2004,32:85~94.
[8]张之源,王培华,张崇岱.巢湖营养化状况评价及水质恢复探讨[J].环境科学研究,1999,12(5):45~48.
[9]Yamamuro M,Kanai Y.A 200-year record of natural andanthropogenic changes in water quality from coastal lagoon sedimentsof Lake Shinji,Japan[J].Chemical Geology,2005,218:51~61.
[10]Meyers P A.Organic geochemical proxies of paleoceanographic,paleolimnologic,and paleoclimatic processes[J].OrganicGeochemistry,1997,27(5/6):213~250.
[11]Hollander D J,Smith M A.Microbially mediated carbon cycling as acontrol on theδ13C of sedimentary carbon in eutrophic Lake Mendota(USA):New models for interpreting isotopic excursions in thesedimentary record[J].Geochimica et Cosmochimica Acta,2001,65(23):4321~4337.
[12]Herczeg A L,Smith A K,Dighton J C.A 120 year record ofchanges in nitrogen and carbon cycling in Lake Alexandrina,SouthAustralia:C:N,δ15N,andδ13C in sediments[J].AppliedGeochemistry,2001,16:73~84.
[13]Andreas L,Gerhard H S,Bernd Z,et al.A Lateglacial andHolocene organic carbon isotope record of lacustrinepalaeoproductivity and climatic change derived from varved lakesediments of Lake Holzmaar,Germany[J].Quaternary ScienceReviews,2003,22:569~580.
[14]顾成军,戴雪荣,张海林.巢湖沉积物粒度特征与沉积环境[J].海洋地质动态,2004,20(10):10~13.
[15]Buchanon D L,Corcoran B J.Sealed tube combustions for thedetermination of carbon-14 and total carbon[J].AnalyticalChemistry,1959,31:1635~1638.
[16]Freudenthal T,Neuer S,Meggers H,et al.Influence of lateralparticle advection and organic matter degradation on sedimentaccumulation and stable nitrogen isotope ratios along a productivitygradient in the Canary Islands region[J].Marine Geology,2001,177:93~109.
[17]Meyers P A.Preservation of elemental and isotope sourceidentification of sedimentary organic matter[J].Chemical Geology,1994,114:289~302.
[18]Meyers P A,Ishiwatari R.Lacustrine organic geochemistry-anoverview of indicators of organic matter sources and diagenesis inlake sediments[J].Organic Geochemistry,1993,20:867~900.
[19]Spiker E C,Hatcher P G.Carbon isotope fractionation of sapropelicorganic matter during early diagenesis[J].Organic Geochemistry,1984,5(4):283~290.
[20]Talbot M R,Johannessen T.A high resolution palaeoclimatic recordfor the last 27,500 years in tropical West Africa from the carbon andnitrogen isotope composition of lacustrine organic matter[J].EarthPlanet Sci Letters,1992,110:23~37.
[21]王苏民,窦鸿身.中国湖泊志[M].北京:科学出版社,1998.80~113.
[22]Maren V,Birger L,Mirja L,et al.Stable isotope signals ofeutrophication in Baltic Sea sediments[J].Journal of MarineSystems,2000,25:287~298.
目录