Analyzing the contribution of climate change to long-term variations in sediment nitrogen sources for reservoirs/lakes.
Analyzing the contribution of climate change to long-term variations in sediment nitrogen sources for reservoirs/lakes.
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DOI：
10.1016/j.scitotenv.2015.03.140
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发表时间：
2015-08
期刊：
影响因子：
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通讯作者：
X. Xia;Qiong Wu;B. Zhu;Pujun Zhao;Shangwei Zhang;Lingyan Yang
中科院分区：
文献类型：
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作者：
X. Xia;Qiong Wu;B. Zhu;Pujun Zhao;Shangwei Zhang;Lingyan Yang
应用基于稳定同位素δ 13 C、δ 15 N和C：N比值的混合模型估算了多种来源氮对沉积物氮的贡献。我们还开发了一个概念模型，描述和分析气候变化对氮富集的影响。利用210 Pb和137 Cs测年的沉积物样品，在密云水库进行了两种模式的模拟，分析了气候变化对沉积物氮源变化的贡献。结果表明，近50年来，土壤和肥料、沉水植物、固氮浮游植物和非固氮浮游植物的平均贡献率分别为40.7%、40.3%、11.8%和7.2%。此外，1960 - 2010年沉积物总氮含量呈显著增加趋势，沉水植物和浮游植物来源的沉积物氮在过去50年中均呈显著增加趋势。相比之下，土壤和肥料来源在1990年至2010年期间呈显著下降趋势。从固氮浮游植物的变化趋势来看，温度和日照时数的变化至少可以解释近50年来沉积物氮富集趋势的43%。气候因子对氮源的回归分析表明，降水、温度和日照时数对沉积物氮源变化的贡献率为18.5%~ 60.3%。研究表明，混合模型为计算沉积物中多种氮源的贡献提供了一种可靠的方法，浮游固氮植物可作为评价气候变化对氮富集影响的重要响应因子。
We applied a mixing model based on stable isotopic δ13C, δ15N, and C:N ratios to estimate the contributions of multiple sources to sediment nitrogen. We also developed a conceptual model describing and analyzing the impacts of climate change on nitrogen enrichment. These two models were conducted in Miyun Reservoir to analyze the contribution of climate change to the variations in sediment nitrogen sources based on two210Pb and137Cs dated sediment cores. The results showed that during the past 50 years, average contributions of soil and fertilizer, submerged macrophytes, N2-fixing phytoplankton, and non-N2-fixing phytoplankton were 40.7%, 40.3%, 11.8%, and 7.2%, respectively. In addition, total nitrogen (TN) contents in sediment showed significant increasing trends from 1960 to 2010, and sediment nitrogen of both submerged macrophytes and phytoplankton sources exhibited significant increasing trends during the past 50 years. In contrast, soil and fertilizer sources showed a significant decreasing trend from 1990 to 2010. According to the changing trend of N2-fixing phytoplankton, changes of temperature and sunshine duration accounted for at least 43% of the trend in the sediment nitrogen enrichment over the past 50 years. Regression analysis of the climatic factors on nitrogen sources showed that the contributions of precipitation, temperature, and sunshine duration to the variations in sediment nitrogen sources ranged from 18.5% to 60.3%. The study demonstrates that the mixing model provides a robust method for calculating the contribution of multiple nitrogen sources in sediment, and this study also suggests that N2-fixing phytoplankton could be regarded as an important response factor for assessing the impacts of climate change on nitrogen enrichment.