Spatio-temporal distribution of heavy metals in sediments of Biyyam Backwater, Kerala, Southwest India; its environmental implications

Abstract

Biyyam backwater is a developing eco-tourism hub and prone to increased pollution due to urbanization and agricultural waste disposal. This study investigates the distribution, temporal variation, enrichment and accumulation of heavy metals in the surface sediments from Biyyam backwaters. Samples were collected from four locations during post-monsoon (December 2017), pre-monsoon (March 2018) and monsoon (July 2018) seasons. Sediment texture, organic matter and heavy metals such as Mn, Co, Zn, Ni, Cr, Pb, Sc, Cd, and As were analyzed. The metal concentration in surface sediments decreased in the following order, i.e., Mn > Cr > Zn > Ni > Pb > As > Co > Sc > Cd. Spatio-temporal variability in distribution pattern of heavy metals show higher concentrations in upstream region. Heavy metal concentrations in surface sediments show relatively higher Igeo factors indicating contribution of heavy metals from agricultural and urban waste disposal. These relatively high values indicate that the Biyyam backwater is threatened by metal contamination, specifically by As, Cd, Cr and Ni. Biyyam backwater is an eco-tourism hub and a beautiful aquatic ecosystem, thus our results would help the local environmental managers to develop strategies to conserve the natural state of the kayal via managing the sources of pollution and sediment remediation in the area.