摘要
本次研究选择中国东部一个生态和环境空间分异极大的浅水湖泊（太湖）以及周围河流，分别于2003年7月和9月两次采集湖水和河水样品，分析其中的N2O浓度，并利用扩散模型公式估算水-气界面N2O交换通量。结果显示N2O饱和度的空间变化从70％不饱和到2708％过饱和变化范围很大。N2O饱和度的空间分布，N2O与CH4、无机氮、TDS（总溶解固体物质）之间的相关性都表明：太湖重度富营养区N2O的产生极大地受到人为N输入的影响。然而，初步的通量分析显示湖泊N2O的释放因子不超过0．63％，小于河流巾的默认值，N2O产率也略低于水环境中的平均值，太湖以面积为权重的释放通量平均值并不高，在7月和9月分别为14．0μmol／m2·d和9．7μmol／m2·d。这些结果表明流域人为N输入对整个湖泊N2O的促进作用是有限的，预计未来湖泊N2O释放不会因为人为活动增加而出现大幅度增加的状况。流域内各生态景观N2O释放量的比较，也表明富营养湖泊总体上仍然是一个十分有限的大气N2O释放源。相反，太湖周围河流存在较大的N2O释放速率，在7月和9月估算的N2O释放通量分别为142．11μmol／m2·d和28．8μmol／m2·d。将这一释放速率推广到整个流域后，预计河网的N2O释放量将占到耕作土壤的10％～50％，显示了河流对区域N2O质量平衡具有较重要的影响。
In this study,NzO saturations were examined in July and September of 2003 in an ecologically heterogeneous lake,the Lake Taihu, and its surrounding rivers in Eastern China. N2O emissions were estimated and compared with those from the other landscapes within the Lake Taihu drainage basin. Results display that there is a large difference of N2O saturation,from 70% un-saturation to as much as 2708% super-saturation,in space. Correlations between N2O and CH4, inorganic N concentrations and TDS indicate that enhancement of the anthropogenically induced N input is the primary factor to control distribution of N2O saturation in the heavily nutrients-polluted northern area only. Overall,the N2O emission factor（0.63%）from the lake is less than the suggested default from rivers. N2O productivity is slightly less than average in fresh-and salted-water environments. The surface area- weighted averages of N2O emission fluxes （14.0 μmol/m2·d in July and 9.7μmol/m2·d in September 2003 ）in Lake Taihu suggest that eutrophied lakes, as a whole, still represent a very limited global contribution to N2O emission to the atmosphere. Comparatively, the N2O emission rates（ 142. 1μmol/m2·d in July and 28.8μmol/m2·d in September）in the surrounding rivers are higher than those from cultivated lands in the watershed. The total emissions from the dense river network in the entire Lake Taihu drainage basin are between 10% -50% （depending on different months） ,indicating an important effect from polluted rivers on regional N2O budget.
出处
《第四纪研究》
CAS
CSCD
北大核心
2009年第1期144-152,共9页
Quaternary Sciences
基金
贵州省自然科学基金项目（批准号：J-[2007]2083）、国家自然科学基金项目（批准号：40873013,90610037和40073032）、国家重点基础研究发展规划项目（批准号：2002CB412300）和中国科学院海外合作伙伴计划项目共同资助
关键词
氧化亚氮(N2O)
空间变化
人为污染
富营养湖泊
中国东部
nitrous oxide （ N2O） , spatial variation, anthropogenic pollution, eutrophic lake, Eastern China
