Chilika lake, the largest brackish water lagoon in Asia, has a unique setting, where the north-eastern part receives freshwater from the terrestrial runoff, and the south-eastern part receives seawater from the Bay of Bengal. The seasonal variability in the quantity of inflowing water and their mixing in the lake controls the mobilization and precipitation of various elements. Seasonal sediment samples were collected from both the river and seawater influenced regions of the lake to understand the spatio-seasonal distributions of various elements along the salinity gradient. The major elements present in the sediments are mostly derived from the parent rock weathering in the source region and subsequently transported into the lake by the rivers. Seasonal variations in trace element concentrations are more prominent in the north-eastern part of the lake (i.e., low salinity region), and their higher concentrations have been observed during the post-rainy period. The affinity of the elements (Al, Fe, Mn, Li, V, Co, Cr, Cu, Th, and Zn) towards fine-grain sediments suggests that the size distribution pattern controls their accumulation, retention, and remobilization. The concentrations of Cr, Cu, and Pb exceeded the effects range low, and effects range median benchmarks indicating the potential biological risk in the low salinity region as compared to the high salinity region. The statistical analysis indicated that the concentrations of elements in the region proximal to the sea mouth are controlled by grain size and physicochemical condition of the lake water. In contrast, the element concentrations in the interior region are associated with anthropogenic activities and weathering processes. Continuous monitoring and assessment of element concentrations of the lake sediments can help to protect the lake ecology from the harmful element contaminations.

中文翻译：

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盐度和粒度分布变化对Chilika湖表层沉积物中元素分布的季节性和空间变化

Chilika湖是亚洲最大的微咸水泻湖，拥有独特的环境，东北部接收来自地面径流的淡水，而东南部接收来自孟加拉湾的海水。入湖水量的季节性变化及其在湖泊中的混合控制着各种元素的动员和降水。从河流和受海水影响的湖泊地区收集季节性沉积物样本，以了解沿盐度梯度的各种元素的时空分布。沉积物中的主要元素主要来自母岩在源区的风化作用，随后被河流运入湖泊。在湖的东北部（即低盐度地区），微量元素浓度的季节性变化更为明显，而在雨后时期则观察到其较高的浓度。元素（Al，Fe，Mn，Li，V，Co，Cr，Cu，Th和Zn）对细颗粒沉积物的亲和力表明大小分布模式控制着它们的积累，保留和迁移。Cr，Cu和Pb的浓度超出了低影响范围，并且影响范围中位数基准表明与高盐度区域相比，低盐度区域具有潜在的生物风险。统计分析表明，靠近海口的区域中元素的浓度受湖泊水的粒径和理化条件控制。相反，内部区域的元素浓度与人为活动和风化过程有关。连续监测和评估湖泊沉积物中元素的浓度可以帮助保护湖泊生态免受有害元素的污染。