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贵州百花湖分层晚期有机质降解过程与溶解N2O循环
引用本文:王仕禄,刘丛强,万国江,陶发祥,李军,朱兆洲,吕迎春.贵州百花湖分层晚期有机质降解过程与溶解N2O循环[J].第四纪研究,2004,24(5):569-577.
作者姓名:王仕禄  刘丛强  万国江  陶发祥  李军  朱兆洲  吕迎春
作者单位:中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳,550002
基金项目:国家自然科学基金项目 (批准号 :40 0 73 0 3 2和 4990 3 0 0 7),中国科学院知识创新工程 (批准号 :KZCX1-SW -12 -Ⅱ -0 3 -0 1和KZCX2 -10 5 )资助
摘    要:百花湖是一个具有季节性分层的富营养小型湖泊,在秋季湖水倒转期经常发生水质恶化事件,碳氮循环出现异常。文章研究特选择在秋初,湖泊分层开始消失时,测定了湖水中不同深度的N2O,CH4,CO2,有机和无机碳同位素以及其他化学参数变化。结果发现:采样时百花湖在约6m和16m深度附近出现了两个温度不连续层(SDL和PDL),并影响到有机颗粒的沉降和分解。相对而言,有较多的有机质在这两个层内发生降解,但降解的途径有所不同,上部主要是有氧降解,下部则主要是无氧降解过程。N2O的产生和消耗与有机质的降解过程完全对应:PDL层以上,ΔN2O与AOU的线性关系反映了N2O主要形成于硝化作用;PDL层以下反硝化作用导致N2O严重不饱和;PDL内位于硝化作用和反硝化作用过渡带的N2O峰,显然是硝化与反硝化联合作用的结果。PDL层内较大的CH4浓度变化梯度,说明嗜甲烷细菌可能通过氧化NH+4贡献了部分N2O。百花湖秋、冬季表层湖水N2O都是过饱和的,都是大气N2O的源,依据分子扩散模型计算湖泊N2O的释放通量在12~14μmol/m·day之间,秋、冬季没有明显的差别。秋季底层湖水的反硝化作用是湖泊N2O的汇,其消耗通量与表层的释放通量基本相当。

关 键 词:分层湖泊  有机质降解  碳同位素  硝化与反硝化作用  溶解N2O  源汇效应
文章编号:1001-7410(2004)05-569-09
收稿时间:2004-02-12
修稿时间:2004年2月12日

DECOMPOSITION OF ORGANIC MATTER AND N2O CYCLING IN LAKE BAIHUA,GUIZHOU DURING THE LATE STRATIFICATION
Institution:The State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002
Abstract:Lake Baihua is a small euthophic lake with a seasonally anoxic hypolimnia, where seasonal deterioration of water quality very often happens during the fall turn over. In this paper N 2O, CO 2, CH 4, carbon isotope and some physical and chemical parameters are determined in fall when the stratification begin to disappear. The results show that two discontinuity layers, SDL and PDL, occur at the depth of about 6 and 16 meters, respectively. Relatively, more organic matter is decomposed in these two discontinuous layers. However, the mechanisms are different. It is aerobic decomposition in SDL and anaerobic in and below PDL. The production and consumption of nitrous oxide perfectly accord with the processes of decomposition of organic matter: Above the PDL, a good positive correlation between Δ N 2O and AOU suggests that nitrous oxide is produced by nitrification. Below the PDL, the undersaturation of N 2O is ascribed to denitrification to N 2, and the peak of N 2O in PDL evidently results from the coupling of nitrification and denitrification. It is also likely that N 2O is partially produced through the oxidation of NH + 4 by the methanotrophic bacteria. Surface water N 2O is super saturated with atmospheric N 2O in both fall and winter. The flux of N 2O emission is estimated to be about 12~14μmol/m 2·day in fall and winter without distinct seasonal difference. The denitrification of N 2O to N 2 in hypolimnia result in a depletion of approximatey 6~13μmol/m 2·day.
Keywords:stratified lake  decomposition of organic matter  carbon isotope  dissolved N  2O  nitrification  denirification  source  sink effect  
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