ABSTRACT

Coimbatore is one of the industrial cities in Tamil Nadu, India, which has been experiencing rapid urbanization and population growth. Coimbatore is also known for its unique freshwater lakes environment and serves as a rich ecosystem. However, the assessment of heavy metal levels in aquatic environments is limited. This study was aimed to investigate physicochemical parameters, heavy metals level and sources, and ecotoxicity in sediments collected from five different lakes in Coimbatore. The concentrations of heavy metals (Cr, Cu, Zn, As, Cd, and Pb) in sediments were determined by Inductive Coupled Plasma-Mass Spectroscopy (ICP-MS). Hg level was measured using Advanced Mercury Analyzer (AMA). The determined heavy metal concentrations in sediments varied significantly according to the lake location and consistent with local human linked anthropogenic activities. The metal concentrations in urban lakes were exceeding both the Sediment Quality Guidelines (SQGs) and the probable effect levels” (PELs) mostly; e.g., in sediments from the Lake Ukkadam, the values of 5.08 and 203.32 mg kg-1 dry weight were observed for Hg and Cu, respectively. The ecotoxicity test with ostracods exposed to the sediment samples revealed that mortality ranged between 6 and 23% for countryside lakes and 28 and 88% for the lakes within urban Zone. We used Spearman rank-order correlation and Principal components analysis (PCA) to assess the sources of pollutants and if they related to anthropogenic pressure and eutrophication of lakes. The main sources of heavy metals from studied lakes differed significantly. Urban and industrial effluents were dominant sources in urban lakes. Agricultural runoff, domestic wastes, and natural weathering were responsible for the metal sources in country lakes. This study provides baseline information on the heavy metal pollution status of sediments in the freshwater lakes in Coimbatore, which will be useful for pollution control measures to prevent possible metal sources on these lakes and impose appropriate management practices and continuous monitoring by relevant authorities.

摘要

哥印拜陀是印度泰米尔纳德邦的工业城市之一，该城市一直在经历快速的城市化进程和人口增长。哥印拜陀也以其独特的淡水湖泊环境而闻名，并拥有丰富的生态系统。但是，对水生环境中重金属含量的评估是有限的。这项研究旨在调查从哥印拜陀的五个不同湖泊收集的沉积物中的理化参数，重金属含量和来源以及生态毒性。沉积物中重金属（Cr，Cu，Zn，As，Cd和Pb）的浓度通过电感耦合等离子体质谱法（ICP-MS）测定。使用高级汞分析仪（AMA）测量汞含量。所确定的沉积物中重金属的浓度根据湖泊的位置而变化很大，并且与当地人类活动有关。城市湖泊中的金属浓度大部分都超过了《沉积物质量准则》和“可能的影响水平”（PEL）。例如，在来自乌卡丹湖的沉积物中，汞和铜的干重分别为5.08和203.32 mg kg-1。暴露于沉积物样品中的杀虫剂的生态毒性测试表明，农村湖泊的死亡率在6％到23％之间，而市区内湖泊的死亡率在28％到88％之间。我们使用Spearman等级相关性和主成分分析（PCA）来评估污染物的来源以及它们是否与人为压力和湖泊富营养化有关。来自研究湖泊的重金属的主要来源差异很大。城市和工业废水是城市湖泊的主要来源。农业径流，生活垃圾和自然风化是造成乡村湖泊中金属来源的原因。这项研究提供了有关哥印拜陀淡水湖泊中沉积物重金属污染状况的基线信息，这将有助于采取污染控制措施，防止这些湖泊中可能的金属来源，并采取适当的管理措施并由有关当局进行持续监测。