基于“源-汇”理论的资江下游地区非点源污染风险区划

Zonation on non-point source pollution risk in the lower reaches of Zijiang River based on the“source-sink”theory

开展非点源污染风险评估及区划研究对流域生态环境保护、土地利用结构调整和优化具有重要意义。以2010、2018年两期资江下游地区土地利用覆盖数据为基础,基于"源-汇"景观格局理论识别"源"、"汇"景观,综合考虑非点源污染发生和迁移因子的前提下,借助景观空间负荷对比指数(LCI)、非点源污染负荷指数(NPPRI),分析非点源污染风险的时空变化特征;通过识别非点源污染风险中的关键因子,对资江下游非点源污染区划进行分析。结果表明:研究区非点源污染发生风险总体较低,"汇"景观为主的子流域占61.2%;非点源污染风险呈现西南低,东北平原区以及资江干流、志溪河、桃花江沿岸偏高的空间特征;2010—2018年,非点源污染风险呈现升高趋势,农村居民点、耕地的扩张及林地缩减对非点源污染发生风险分别具有正向与负向的响应关系;LCI、坡度、距离是影响非点源污染风险指数变化的关键因子。在此基础上,将资江下游地区划分为4个控制区,即近河道污染治理区、低坡地污染控制区、生态恢复-风险防控区、生态优先保护区。

Non-point source pollution risk assessment and zonation research are of great significance for the eco-environmental protection and optimization of land use structure.We identified the"source"and"sink"landscape using the"source-sink"landscape pattern theory based on the two phases of land use data in the lower reaches of Zijiang River in 2010 and 2018.We comprehensively considered the non-point source pollution occurrence and migration factors,and used location-weighted landscape contrast index(LCI)and non-point source pollution load index(NPPRI)to analyze non-point source pollution risk spatio-temporal characteristics in the study area.Zonation on non-point source pollution in the lower reaches of Zijiang River was studied by identifying the key factors of non-point source pollution risk.The results showed that the overall risk of non-point source pollution was relatively low.The sub-basin with"sink"landscape was the main type,accounting for 61.2%.Non-point source pollution risk was low in the southwest and was high along the banks of Zhixi River,Taohua River and main stream of Zijiang River,as well as plain in the northeast of the lower Zijiang River.The risk of non-point source pollution from 2010 to 2018 showed an increasing trend.The changes in landscape pattern,especially the expansion of rural settlement,arable land and the shrinkage of forest land had positive and negative responses to the risk of non-point source pollution,respectively.LCI,slope,and distance were the key factors affecting the change of the risk index of non-point source pollution.The lower reaches of the Zijiang River could be divided into four control regions:pollution treatment area near river,low slope pollution control area,ecological restoration-risk prevention and control area,and ecological priority protection area.