Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
Zhumadian City Bureau of Environmental Protection, Zhumadian 463000, China.
Water Res. 2016 May 1;94:187-199. doi: 10.1016/j.watres.2016.02.040. Epub 2016 Feb 18.
Environmental problems such as eutrophication caused by excessive nutrient discharge are global challenges. There are complex pollution sources of nitrogen (N) discharge in many river basins worldwide. Knowledge of its pollution sources and their respective load contributions is essential to developing effective N pollution control strategies. N loads from all known anthropogenic pollution sources in the Upper Huai River basin of China were simulated with the process-based SWAT (Soil and Water Assessment Tool) model. The performances of SWAT driven by daily and hourly rainfall inputs were assessed and it was found that the one driven by hourly rainfall outperformed the one driven by daily rainfall in simulating both total nitrogen (TN) and ammonia nitrogen (NH4-N) loads. The hourly SWAT model was hence used to examine the spatiotemporal patterns of TN and NH4-N loads and their source attributions. TN load exhibited significant seasonal variations with the largest in summer and the smallest in spring. Despite its declining proportion of contribution downstream, crop production remained the largest contributor of TN load followed by septic tanks, concentrated animal feedlot operations (CAFOs), municipal sewage treatment plants, industries, and scattered animal feedlot operations (SAFOs). There was much less seasonal variation in NH4-N load. CAFOs remained the largest source of NH4-N load throughout the basin, while contributions from industries and municipal sewage treatment plants were more evident downstream. Our study results suggest the need to shift the focus of N load reduction from "end-of-pipe" sewage treatment to an integrated approach emphasizing stakeholder involvement and source prevention.
环境问题，如过度营养物排放引起的富营养化，是全球性的挑战。全球许多流域的氮（N）排放存在复杂的污染源。了解其污染源及其各自的负荷贡献对于制定有效的 N 污染控制策略至关重要。采用基于过程的 SWAT（土壤和水评估工具）模型模拟了中国淮河流域所有已知人为污染源的 N 负荷。评估了由日降雨量和小时降雨量驱动的 SWAT 的性能，发现由小时降雨量驱动的模型在模拟总氮（TN）和氨氮（NH4-N）负荷方面优于由日降雨量驱动的模型。因此，使用小时 SWAT 模型来研究 TN 和 NH4-N 负荷的时空模式及其来源归因。TN 负荷表现出显著的季节性变化，夏季最大，春季最小。尽管下游的贡献比例下降，但农作物生产仍然是 TN 负荷的最大贡献者，其次是化粪池、集中式动物饲养场（CAFO）、城市污水处理厂、工业和分散式动物饲养场（SAFO）。NH4-N 负荷的季节性变化较小。整个流域，CAFO 仍然是 NH4-N 负荷的最大来源，而工业和城市污水处理厂的贡献在下游更为明显。我们的研究结果表明，需要将 N 负荷减少的重点从“末端处理”污水处理转移到强调利益相关者参与和源头预防的综合方法上。
