Abstract：
Many urban water bodies grapple with low flow flux and weak hydrodynamics. To address these issues, projects have been implemented to form integrated urban water bodies via interconnecting artificial lake or ponds with rivers, but causing pollution accumulation downstream and eutrophication. Despite it is crucial to assess eutrophication, research on this topic in urban interconnected water bodies is limited, particularly regarding variability and feasible strategies for remediation. This study focused on the Loucun river in Shenzhen, comprising an pond, river and artificial lake, evaluating water quality changes pre-(post-)ecological remediation and establishing a new method for evaluating the water quality index (WQI). The underwater forest project, involving basement improvement, vegetation restoration, and aquatic augmentation, in the artificial lake significantly reduced total nitrogen (by 43.58%), total phosphorus (by 79.17%) and algae density (by 36.90%) compared to pre-remediation, effectively controlling algal bloom. Rainfall, acting as a variable factor, exacerbated downstream nutrient accumulation, increasing total phosphorus by 4.56 times and ammonia nitrogen by 1.30 times compared to the dry season, and leading to algal blooms in the non-restoration pond. The improved WQI method effectively assesses water quality status. The interconnected water body exhibits obvious nutrient accumulation in downstream regions. A combined strategy that reducing nutrient and augmenting flux was verified to alleviate accumulation of nutrients downstream. This study provides valuable insights into pollution management strategies for interconnected pond-river-lake water bodies, offering significant reference for nutrient mitigation in such urban water bodies.
摘要：
许多城市水体都在努力应对低流量和弱流体动力学。为了解决这些问题,已实施项目，通过将人工湖或池塘与河流互连，形成一体化的城市水体，而是导致下游污染积累和富营养化。尽管评估富营养化至关重要，在城市互联水体中对这一主题的研究是有限的，特别是关于可变性和可行的补救策略。本研究以深圳楼村河为研究对象,包括一个池塘，河流和人工湖，评价生态修复前(后)水质变化,建立水质指数(WQI)评价新方法。水下森林项目,涉及地下室的改善，植被恢复,和水生增强，人工湖中的总氮显著减少(43.58%)，与修复前相比，总磷（79.17％）和藻类密度（36.90％），有效控制藻类水华。降雨,作为一个可变因素，加剧了下游养分积累，与旱季相比，总磷增加了4.56倍，氨氮增加了1.30倍，并导致未恢复池塘中的藻类繁殖。改进的WQI方法有效地评估了水质状况。相互联系的水体在下游区域表现出明显的养分积累。验证了减少养分和增加通量的组合策略以减轻下游养分的积累。这项研究为相互连接的池塘-河流-湖泊水体的污染管理策略提供了宝贵的见解，为此类城市水体中的养分缓解提供了重要参考。
