| 1980~2010年浙江某典型河流硝态氮通量对净人类活动氮输入的动态响应 |
| 摘要点击 2123 全文点击 1438 投稿时间：2013-12-26 修订日期：2014-02-13 |
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| 中文关键词 硝态氮 净人类活动氮输入 滞留氮库 动态响应 河流 |
| 英文关键词 nitrate net anthropogenic nitrogen input (NANI) retained nitrogen pools dynamic response river |
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| 中文摘要 |
| 以浙江某典型流域为研究对象，基于1980~2010年的水质水量和氮源数据及LOADEST模型，估算了逐年河流NO3--N通量和净人类活动氮输入（NANI），分析了河流NO3--N通量和NANI的年际演化特征及其动态响应关系，探讨了每年NANI、 滞留氮库、 自然背景源对河流NO3--N通量的贡献. 结果表明，1980~2010年，河流NO3--N通量和NANI总体上都呈现出先增后减的抛物线型变化趋势，均在1998年左右分别达到峰值5.74kg·（hm2·a）-1和77.5kg·（hm2·a）-1；过去31 a，河流NO3--N通量和NANI分别净增加了~42%和~77%. 化肥氮和大气氮沉降是NANI的主要来源，分别占了NANI的~48%和~40%. 河流NO3--N通量的年际变化不仅与NAIN（R2=0.27**）和化肥氮输入量（R2=0.32**）显著相关，而且与河流年均流量（R2=0.79**）或降雨量（R2=0.63**）具有更强的相关性，意味着河流NO3--N的来源除了当年的NAIN，还受滞留氮库的影响. 所建立的以NANI和流量为自变量的回归模型能很好地模拟河流NO3--N通量变化（R2=0.94**）. 该模型预测结果显示，在NANI和流量分别降低30%的情况下，河流年均NO3--N通量将分别减少~21%和~30%；每年的NANI、 滞留氮库、 自然背景源对河流当年NO3--N通量的贡献率分别为~53%、~24%、~23%. 河流NO3--N通量长期的年际变化是NANI和水文要素共同作用的结果；但是，由于滞留氮库的影响，与源控制方式相比，增加"汇"景观应该能更加快速地削减河流NO3--N通量. |
| 英文摘要 |
| Based on long-term records of river water quality and discharge and nitrogen sources as well as the LOADEST model, annual riverine NO3--N flux and net anthropogenic nitrogen input (NANI) were both estimated for a typical river catchment (2474 km2) in Zhejiang Province over the 1980-2010 period. Historical trends in both riverine NO3--N flux and NANI and their dynamic relationships were then fully addressed. Finally, the contributions of annual NANI, retained nitrogen pools, and natural background sources to riverine NO3--N flux were indentified. Results indicated that both riverine NO3--N flux and NANI showed parabolic changing trends with peak value of 5.74 kg·(hm2·a)-1 for flux and 77.5 kg·(hm2·a)-1 for NANI both occurring around 1998. In 1980-2010, net increase of riverine NO3--N flux and NANI was ~42% and ~77%, respectively. Chemical nitrogen fertilizer application and atmospheric nitrogen deposition, which accounted for ~48% and ~40% of NANI, respectively, were the major sources of NANI. Although interannual change of riverine NO3--N flux was significantly related to NANI (R2=0.27**) as well as the chemical nitrogen fertilizer application amount (R2=0.32** ), it showed higher dependence on the river water discharge (R2=0.79**) or precipitation (R2=0.63**), implying that annual riverine NO3--N was not only originated from current year's NANI, but also derived from retained N pools that were ultimately derived from NANI in previous years. A regression model developed by incorporating both NANI and water discharge could account for 94% of the variability of annual NO3--N flux. This model predicted that NO3--N flux could have been reduced by ~21% and ~30% if the annual NANI and water discharge had been cut by 30%, respectively. Annual NANI, retained nitrogen pools, and natural background sources contributed to~53%,~24%, and ~23% of the riverine NO3--N flux, respectively, suggesting that~77% of flux was derived from anthropogenic nitrogen sources. Although observed long-term interannual change of riverine NO3--N flux was dependent on the combined influences of NANI and hydroclimate, a more immediate reduction of riverine NO3--N flux may result from interception strategies than from cutting nitrogen source inputs due to the contribution of retained nitrogen pools. |
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