温度对呼伦湖沉积物有机碳埋藏及矿化影响研究  

EFFECTS OF TEMPERATURE ON ORGANIC CARBON BURIAL AND MINERALIZATION IN SEDIMENTS OF HULUN LAKE

作　　者：张风菊 桂智凡 薛滨[3] 姚书春[3] Zhang Fengju;Gui Zhifan;Xue Bin;Yao Shuchun(School of Geography,Geomatics and Planning,Jiangsu Normal University,Xuzhou 221116,Jiangsu;College of Urban and Environmental Sciences,Hubei Normal University,Huangshi 435002,Hubei;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,Jiangsu)

机构地区：[1]江苏师范大学地理测绘与城乡规划学院,江苏徐州221116 [2]湖北师范大学城市与环境学院,湖北黄石435002 [3]中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,江苏南京210008

出　　处：《第四纪研究》2020年第5期1240-1250,共11页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41807281);国家重点基础研究发展计划项目(批准号:2019YFA0607100);中国科学院南京地理与湖泊研究所湖泊与环境国家重点实验室开放基金项目(批准号:2018SKL003)共同资助。

摘　　要：湖泊作为地球上重要的碳库之一,在全球碳循环中发挥着重要作用。湖泊有机碳埋藏及矿化是决定湖泊碳汇变化的重要因素,厘清其大小及其温度敏感性对于揭示未来全球变化背景下湖泊碳汇功能具有重要意义。本文以内蒙古呼伦湖为例,通过沉积岩芯有机碳含量分析及210Pb、137Cs年代测定,阐述了1850s以来呼伦湖有机碳埋藏速率及其对温度的响应;同时,通过室内培养实验方法揭示了不同温度梯度下湖泊有机碳矿化速率变化。结果表明,1850s以来呼伦湖有机碳含量变化范围为2.71%~4.57%(平均值3.31%),有机碳埋藏速率变化范围为3.60~87.04 g/(m2·a)(平均值为36.34 g/(m2·a))。呼伦湖沉积物有机碳可能主要源于外源输入,但近年来内源有机碳所占比例逐渐增加。室内培养温度范围内有机碳矿化速率为206.15~1158.70 mg/(m2·d)(平均值约为686.10 mg/(m2·d)),且有机碳埋藏速率及矿化速率均表现为随温度升高而增加的趋势。增温对呼伦湖有机碳埋藏的促进作用可能是由其引起的有机碳矿化增加量低于有机碳输入增加量所致,因此,未来全球变暖的大背景下,尽管呼伦湖会因有机碳矿化量增加导致向大气释放的碳增加,但同时湖泊碳储量很可能也会增加,湖泊在区域/全球碳循环中的作用将进一步加强。Lake sediments are well-recognized sites of organic carbon(OC)storage and play a key role in the global carbon cycling.The lake carbon burial and mineralization are important factors in determining the changes of carbon sink.Hence,understanding their values and temperature sensitivity will increase the capability to predict the carbon sink variations under future global change scenarios.In this study,a 74 cm long sediment core(HL2011:49.13°N,117.51°E;2.5 m in water depth)was recovered from Hulun Lake(48.55°~49.33°N,116.97°~117.81°E),Inner Mongolia in 2011.The sediment ages and OC content in the upper 43 cm was analyzed to assess the organic carbon burial rate(OCBR)and its relationship with temperature over the past 150 years.In addition,thirty sediment cores were collected in Hulun Lake in 2016 and the upper 10 cm were transferred to incubation cores(5.4 cm inner diameter and 60 cm height)to determine the changes of OC mineralization rates under different temperatures.The results demonstrated that the total organic carbon(TOC)content in Hulun Lake ranged from 2.71%to 4.57%(the average value was 3.31%),the OCBR varied from 3.60 g/(m2·a)to 87.04 g/(m2·a)(the mean value was 36.34 g/(m2·a)).The OC being buried in Hulun Lake was mainly generated from terrigenous vegetation and the autochthonous OC demonstrated an increasing trend in the recent years.The average OC mineralization rates ranged from 206.15 mg/(m2·d)to 1158.70 mg/(m2·d)(the mean value was 686.10 mg/(m2·d)).Both the OCBR and OC mineralization rates exhibited a strongly positive relationship with temperature,suggesting that higher temperatures lead to more OC mineralization and more OC burial.The pattern of increasing OCBR with temperature was probably caused by the warming-induced increase of OCBR exceeded the decomposition of sediments.Hence,more CO2 will be released to the atmosphere and more OC will be stored in Hulun Lake sediments as global warming proceeds,implying lakes will play a more important role in the regional/global carbon cycle.

关 键 词：温度 有机碳埋藏 有机碳矿化 沉积物 呼伦湖 

分 类 号：P941.78[天文地球—自然地理学] P595