水污染达峰后元素比例失衡引发的新环境风险:以广东沿海为例

New environmental risks caused by the imbalance of element proportion after the peaking of water pollution:A case study of Guangdong coastal area

针对人类活动和环境变化对水质可能带来的影响,本研究收集了广东省沿海城市群入海口水质监测数据,分析了近岸环境的营养元素化学计量及微量元素浓度时空变化的趋势;通过综合污染指数法,评估了2015—2022年间的生态风险演变,利用相关性分析与相关网络分析解析了近岸水环境演变过程中水溶液性质群集间的关联及聚集,最后通过主成分分析揭示了驱动水溶液性质相互作用的关键影响因素.结果表明:广东省河口水体的主要污染物指标在浓度上受到了控制,但B/C、C/N和C/P比值等逐步偏离其自然本底比值,导致水体的微生物能量利用、营养物质固定和元素矿化效率受阻,水质特征不利于进一步的自然利用,干预了水生态的自净化机制与能力;在气候变化影响下的元素比例失衡、限制性元素匮乏等因素将会限制水体的功能发挥,从而引发新的环境风险.由相关性分析和主成分分析可知,亲和组分浓度受多种效应相近的物理化学作用而产生群集效应,由此构建了复杂的元素耦合体系.生态条件和水文环境的快速变化动摇了元素间的比例链条,因此,需建立排放尾水-河流-入海口-海洋联通的水溶液性质的信息反馈,未来的水环境管理应综合考虑水文特征、污染物总量和元素比例阈值.

To investigate the potential impacts of human activities and environmental changes on water quality,this study collected the monitoring data of water quality from the estuaries of coastal urban agglomerations in Guangdong Province,and analyzed the trends of nutrient stoichiometry and trace element concentrations in the nearshore environment.Using the comprehensive pollution index method,we assessed the changes in ecological risks from 2015 to 2022.Additionally,we analyzed the correlation and clustering characteristics of aqueous solution properties(ASPs) indexes during the evolution of the nearshore water environment using correlation analysis and correlation network analysis.Finally,principal component analysis revealed the key factors driving the interactions among ASPs indexes.The results indicated that the concentration of major pollutants in estuarine water bodies in Guangdong Province was under control.However,the B/C,C/N,and C/P ratios gradually deviated from their natural background ratios,obstructing microbial energy utilization,nutrient fixation,and element mineralization efficiencies in water bodies.This led to water quality characteristics that were not favorable for further natural utilization,interfering the self-purification mechanism and capacity of water bodies.Under the influence of climate change,factors such as the unbalanced proportion of elements and the lack of restrictive elements would limit the function of water bodies,resulting in new environmental risks.Based on the correlation analysis and principal component analysis,it was evident that the concentration of compatible components was subject to a variety of physicochemical interactions with similar effects,establishing a complex element coupling system.The rapid changes in ecological conditions and the hydrological environment have disrupted the partitioning chain among elements.Therefore,it is necessary to establish an information feedback mechanism of the ASPs of the tailwater-river-estuary-ocean system.Future water environment management should comprehensively consider the hydrological characteristics,the total amounts of pollutants,and elemental ratio threshold.