| 太湖氧化亚氮(N2O)排放特征及潜在驱动因素 |
| 摘要点击 4762 全文点击 525 投稿时间：2021-11-02 修订日期：2022-01-05 |
| 查看HTML全文
查看全文 查看/发表评论 下载PDF阅读器 |
| 中文关键词 太湖 氧化亚氮(N2O) 通量 溶解性有机物(DOM) 平行因子分析(PARAFAC) |
| 英文关键词 Lake Taihu nitrous oxide(N2O) flux dissolved organic matter (DOM) parallel factor analysis (PARAFAC) |
|
| 中文摘要 |
| 氧化亚氮（N2O）是《京都议定书》规定的6种温室气体之一，其百年增温趋势是CO2的298倍，大气N2O浓度在持续快速增长中.浅水湖泊是大气N2O的重要来源，为探讨富营养湖泊太湖N2O排放的时空变化及潜在驱动因素，于2月（冬）和8月（夏）不同季节下在太湖进行野外观测，采用扩散系数-顶空瓶法观测表层水体N2O浓度［c（N2O）］和排放通量［F（N2O）］，并讨论分析N2O排放的潜在驱动因素.由于溶解性有机物（DOM）光谱是溶解性有机碳（DOC）及溶解性有机氮（DON）来源组成的有效示踪指标，其迁移转化过程亦会释放大量无机氮，改变水体氧化还原电位，因而也能影响N2O排放.结果表明，太湖表层水体N2O的浓度和排放通量表现出的时间变化及空间变化强烈受到季节（水温）差异和营养水平的共同影响，其表层水体c（ČN2O）均值为（19.7±2.7） nmol·L-1，F（N2O）均值为（41.1±1.8）μmol·（m2·d）-1，两者均表现为夏季高于冬季（t-test，P<0.01）；DOM和DOC等有机质的输入累积能够提高水体N2O的产生和排放潜力，其中N2O排放通量与水体类腐殖质组分C1显著正相关，表征陆源输入的荧光峰积分比值IC ：IT及芳香性指标S275-295都表明西北入湖河口区积累了大量陆源类腐殖酸，其转化降解对N2O的产生及排放有较大的贡献.结果显示水温、DOM组成来源和营养水平等均是影响太湖水体N2O排放的重要因素.长期连续观测能更好地全面评估各种因素对水体N2O产生及排放的影响并科学合理地制定减排方案. |
| 英文摘要 |
| Nitrous oxide (N2O) is one of the six greenhouse gases stipulated in the Kyoto Protocol. Its greenhouse potential over the past century was 298 times that of CO2, and the concentration of atmospheric N2O has been continuously and rapidly increasing during the past hundred years. Shallow lakes are an important source of atmospheric N2O. In order to explore the temporal and spatial changes and potential driving factors of N2O emissions from eutrophic water, we conducted field observations in February (winter) and August (summer) in Lake Taihu. We used the coefficient of diffusion-headspace bottle method to trace the variability in the N2O concentration[c(N2O)] and efflux[F(N2O)] from surface water bodies and explored the potential driving factors of N2O emissions. The optical measurements of dissolved organic matter (DOM) are an effective approach for tracing the source and composition of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON). The migration and transformation processes of DOM also release a large amount of inorganic nitrogen, which changes the redox potential of the water column and thereby affects N2O emissions. Our results showed that the variability in c(N2O) and F(N2O) in the surface waters of Lake Taihu were strongly affected by water temperature and nutrient levels. The average c(N2O) of the surface waters was (19.7±2.7) nmol·L-1, corresponding to a mean F(N2O) of (41.1±1.8) μmol·(m2·d)-1, and the means of both c(N2O) and F(N2O) were higher in summer than those in winter (t-test, P<0.01). The input and accumulation of DOM could increase the production and emission potential of N2O in water bodies, as supported by both c(N2O) and F(N2O) significantly increasing with increasing level of terrestrial humic-like C1. The integration ratio of peak C to peak T IC:IT of DOM and the spectral slope S275-295 results indicated that there were high inputs of terrestrial DOM in the northwestern inflowing river mouths, concurring with the high production and emission of N2O found there. This suggested that the accumulation and degradation of terrestrial DOM potentially fueled the emission of N2O. Our results showed that water temperature, DOM composition, and nutrient level were all important factors affecting N2O emission from Lake Taihu. Long-term continuous observation can be applied to better evaluate the impact of various environmental factors on the production and emission of N2O in water bodies and to help with providing scientific emission reduction plans. |
|
|
|
