Abstract The rapid industrialization and urbanization that have occurred in East China in recent decades pose a threat to the local aquatic ecosystem. Pollution by heavy metals is one of the factors that threaten the environment, and assessing the risk of heavy metals is essential for promoting proper freshwater management in aquatic ecosystems. In this study, 121 surface sediment samples were collected from 63 shallow freshwater lakes in the middle and lower reaches of the Yangtze and Huai River Basins (MLYHB) to study the spatial distribution of common heavy metals, including As, Cd, Cr, Cu, Ni, Pb, and Zn. Multivariate statistical analysis, which based on the metals' distribution and geoaccumulation index (Igeo), sediment quality guidelines (SQGs), potential ecological risk (PER) index, and risk index (RI), was conducted to elucidate the pollution source and evaluate the potential ecological risks. The average concentrations of As, Cd, Cr, Cu, Ni, Pb, and Zn in the surface sediments were 22.6, 1.1, 74.6, 47.6, 38.3, 37.3, and 141.9 mg/kg, respectively. The concentrations of these metals in the surface sediments from the middle reaches were generally higher than those in sediments from the lower reaches of MLYHB. The concentrations of Cr and Ni were similar to the background values, and they mostly originated from natural detritus. Cd pollution was predominant in MLYHB, and the Zn, Cd, Cu, and Pb in the surface sediments mainly originated from industrial and agricultural activities, while As originated from pollution due to coal combustion. According to the SQGs and PER, Cr, Cu, Ni, Pb, and Zn likely pose a low ecological risk, while As and Cd were identified as the priority pollutants by the two methods, respectively, and may pose a high ecological risk to the aquatic ecosystem in MLYHB. Moreover, the PER of heavy metals in surface sediments is more severe in the middle reaches of MLYHB than that in the lower reaches. The middle reaches of MLYHB should be the priority regions for environmental monitoring and management.

中文翻译：

---

华东浅湖表层沉积物重金属污染空间分布及生态风险评价

摘要 近几十年来，华东地区快速的工业化和城市化进程对当地的水生生态系统构成了威胁。重金属污染是威胁环境的因素之一，评估重金属风险对于促进水生生态系统中适当的淡水管理至关重要。本研究从长江和淮河流域中下游的 63 个浅淡水湖（MLYHB）采集 121 个表层沉积物样品，研究常见重金属的空间分布，包括 As、Cd、Cr、Cu、镍、铅和锌。基于金属分布和地质积累指数（Igeo）、沉积物质量指南（SQGs）、潜在生态风险（PER）指数和风险指数（RI）的多元统计分析，明确污染源，评估潜在生态风险。表层沉积物中As、Cd、Cr、Cu、Ni、Pb和Zn的平均浓度分别为22.6、1.1、74.6、47.6、38.3、37.3和141.9 mg/kg。中游表层沉积物中这些金属的浓度普遍高于MLYHB下游沉积物中的浓度。Cr 和 Ni 的浓度与背景值相似，主要来源于天然碎屑。MLYHB以Cd污染为主，表层沉积物中Zn、Cd、Cu、Pb主要来源于工农业活动，而As来源于燃煤污染。根据 SQGs 和 PER，Cr、Cu、Ni、Pb 和 Zn 可能构成低生态风险，而As和Cd分别被两种方法确定为优先污染物，可能对MLYHB的水生生态系统构成较高的生态风险。此外，MLYHB 中游表层沉积物中重金属的 PER 比下游更严重。MLYHB 中游地区应作为环境监测和管理的重点区域。