Heavy metal contamination and geochemical dynamics in a revdanda creek sediment: Implications for biodiversity and traditional fisheries

Revdanda creek ecosystems are vital for local biodiversity and traditional fisheries but are increasingly threatened by contaminant influx. Sediments act as a major sink for pollutants like heavy metals, yet their seasonal dynamics and ecological impacts are often poorly quantified. This study provides a comprehensive, seasonal assessment of sediment geochemistry in this creek to evaluate its implications for biodiversity and traditional fishing practices. We analyzed surface sediment samples for ten key parameters—Total Organic Carbon (TOC), Cadmium (Cd), Arsenic (As), Zinc (Zn), Lead (Pb), Iron (Fe), Chromium (Cr), Copper (Cu), Mercury (Hg), and Manganese (Mn)—from two distinct stations over a two-year period, covering the pre-monsoon, monsoon, post-monsoon, and summer seasons. The data reveals an extreme, seasonal pattern of organic enrichment. TOC levels at both stations skyrocketed during winter, reaching 3470 and 4070 mg/kg, vastly exceeding the common sediment quality guideline of 500 mg/kg. Concurrently, Arsenic (As) levels at Station 1 (0.5 mg/kg) exceeded the limit in two seasons. Manganese also showed exceedances, while other metals were generally within safe limits. The chronically high, and seasonally extreme, levels of organic carbon indicate a system facing severe eutrophication. This can lead to oxygen depletion in the sediment (hypoxia), eliminating oxygen-sensitive benthic organisms and disrupting the entire food web that supports fish. The co-occurrence of elevated Arsenic and Manganese adds a layer of toxic stress. This degraded benthic habitat directly threatens the sustainability of the traditional fisheries that depend on a healthy creek ecosystem. Immediate action is needed to identify and manage the sources of this organic pollution.