Abstract
The present surface sediment assessment in two temperate lacustrine ecosystems in the region of anthro-urban intensification in less than a century of progressive human history identifies ecosystem responses through space-time monitoring of variable spectrum and their gradients. Sediments have almost no outliers in box-plots across the select sites that suggest their tranquil nature. But temporal fluctuations in pH, bicarbonates, conductivity, OC, OM, TN and C/N can be visualised during Ca-Si dominance. The estimated percentage elemental composition of surface sediments on dry weight basis revealed the order Si > Ca > Mg > K > Na > P > S > Cl. Besides, the micro and trace element quantification represent the descending series of Fe > Al > Zn > Mn > Cu > Cr > Ni > Co > As > Sn > Pb > Cd while Hg and Se remained below detection level (BDL). Sediment pH remained on the basic side but slight acidic nature is noticed during late summer. Significant correlation occurs for conductivity with organic C and organic matter (p geo) scale labels “Unpolluted” to “Highly Polluted” element groups in sediments. The construal of Contamination Factor differentiates between “Contaminated” and “Uncontaminated” score of elements. Integrated Pollution Index (IPI) and Pollution Load Index (PLI) also categorize the sites and lakes. Sediment Quality Guidelines (SQG’s) when compared to observed mean values for various elements point to pollution status and associated ecological risks involved.
Highlights
Sediments constitute a vital abiotic component of aquatic ecosystems and a major nutrient pool archiving historical hydroclimatic records [1]
Temporal fluctuations in pH, bicarbonates, conductivity, organic C (OC), organic matter (OM), total N (TN) and C/N can be visualised during Ca-Si dominance
Significant correlation occurs for conductivity with organic C and organic matter (p < 0.01) as the latter serves an established source for nutrient ions
Summary
Sediments constitute a vital abiotic component of aquatic ecosystems and a major nutrient pool archiving historical hydroclimatic records [1]. Sediment characterisation regulates nutrient cycling and contributes to overall structure and function of the system. They act as pollutant monitoring indicators of aquatic ecosystems [2] [3]. The various nutrients assimilated by aquatic organisms get incorporated into their biomass and mineralized either in organic or inorganic form in the sediments. The surface sediments conduct biogeochemical exchange with the overlying water column [6] depending upon the physicochemical and microbiological properties of the duo. [7] proclaimed water quality is modified on account of sediment (source) supplied contaminants facilitated by their collective physicochemical properties in the company of meteorological and hydrologic features of the watershed.
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