Abstract Freshwater lakes are one of the most vulnerable ecosystems to environmental contamination. This study was initiated to assess the spatial distribution, fractionation, ecological risk of selected potentially toxic metals (Pb, Zn, Cu, Cr, and Ni) in bottom sediments of the Zarivar lake, the second largest freshwater lake in Iran. The results revealed that Pb, Zn and Cu had the high spatial variability (coefficient of variation >50) across the sampling sites and their maximum concentrations (197.5 for Pb, 198.7 for Zn and 185.6 mg/kg for Cu) were observed in sampling sites from the northern, western and eastern margins of the lake. Cr and Ni with average concentrations of 28.3 and 31.38 mg/kg respectively, exhibited low spatial variability (coefficient of variation Cu > Zn > Cr > Ni. Results from the modified five-step sequential extraction analysis indicated that 40 % of total Pb and Zn were associated with the reducible fraction, 45 % of Cu with the oxidizable fraction and more than 80 % of total Ni and Cr were retrieved from the residual fraction. It was also noticed that Pb, Zn and Cu were more incorporated into the non-residual fractions in the sites with a higher total concentration of these metals, suggesting that both total concentration and fractionation behavior of metals were influenced by their potential sources in the study area. Ecological risk assessment using the potential ecological risk index (PERI) and the modified potential ecological risk index (MPERI) showed that sediments from the eight sampling sites pose a moderate to considerable risk whereas the other sites had low ecological risk level. In comparison to sediment quality guidelines (SQGs), the effects range low (ERL) and probable effect level (PEL) values for Pb, Cu and Zn were exceeded at some sampling sites while Ni and Cr concentrations were found to be below or close to their SQGs values at all the sampling sites. Pb was generally identified as the contaminant of most concern in the study area. Taking into account the results obtained from the fractionation study and the source contribution estimate, it can be inferred that the Pb, Zn and Cu with the average contribution of 79, 54 and 64 % respectively, were mainly derived from anthropogenic sources whereas Ni and Cr with the estimated contribution of 80 and 89 % were predominately from the lithogenic source.

中文翻译：

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扎里瓦尔淡水湖（伊朗西北部）底部沉积物中潜在有毒金属的空间分布、分馏和生态风险评估

摘要 淡水湖泊是最容易受到环境污染的生态系统之一。本研究旨在评估伊朗第二大淡水湖 Zarivar 湖底部沉积物中选定的潜在有毒金属（Pb、Zn、Cu、Cr 和 Ni）的空间分布、分馏和生态风险。结果表明，铅、锌和铜在采样点之间具有较高的空间变异性（变异系数 >50），并且在采样点观察到它们的最大浓度（Pb 为 197.5，Zn 为 198.7，Cu 为 185.6 mg/kg）来自湖的北部、西部和东部边缘。平均浓度分别为 28.3 和 31.38 mg/kg 的 Cr 和 Ni 表现出较低的空间变异性（变异系数 Cu > Zn > Cr > Ni。改进后的五步顺序萃取分析结果表明，40% 的 Pb 和 Zn 与可还原部分相关，45% 的 Cu 与可氧化部分相关，总 Ni 和 Cr 的 80% 以上与残余部分相关. 还注意到，在这些金属总浓度较高的位置，Pb、Zn 和 Cu 被更多地纳入非残留部分，这表明金属的总浓度和分馏行为都受其潜在来源的影响。区域。使用潜在生态风险指数（PERI）和修正潜在生态风险指数（MPERI）的生态风险评估表明，来自八个采样点的沉积物具有中等至相当大的风险，而其他采样点的生态风险水平较低。与沉积物质量指南 (SQG) 相比，某些采样点的 Pb、Cu 和 Zn 的影响范围低 (ERL) 和可能影响水平 (PEL) 值被超过，而发现 Ni 和 Cr 的浓度低于或接近于他们在所有采样点的 SQG 值。铅通常被确定为研究区域中最受关注的污染物。考虑到分馏研究的结果和来源贡献估计，可以推断出平均贡献分别为 79%、54% 和 64% 的 Pb、Zn 和 Cu 主要来自人为来源，而 Ni 和 Cr估计 80% 和 89% 的贡献主要来自成岩源。一些采样点的 Cu 和 Zn 超标，而所有采样点的 Ni 和 Cr 浓度都低于或接近其 SQG 值。铅通常被确定为研究区域中最受关注的污染物。考虑到分馏研究的结果和来源贡献估计，可以推断出平均贡献分别为 79%、54% 和 64% 的 Pb、Zn 和 Cu 主要来自人为来源，而 Ni 和 Cr估计 80% 和 89% 的贡献主要来自成岩源。一些采样点的 Cu 和 Zn 超标，而所有采样点的 Ni 和 Cr 浓度都低于或接近其 SQG 值。铅通常被确定为研究区域中最受关注的污染物。考虑到分馏研究的结果和来源贡献估计，可以推断出平均贡献分别为 79%、54% 和 64% 的 Pb、Zn 和 Cu 主要来自人为来源，而 Ni 和 Cr估计 80% 和 89% 的贡献主要来自成岩源。