Spatial and temporal variation in distribution of metals in bed sediments of Subarnarekha River, India

Abstract

The concentration and distribution of selected metals were studied in the bed sediments of Subarnarekha River to assess the spatial and temporal variations and to determine the extent of anthropogenic inputs into the river. Bed sediments were collected from 21 locations for post-monsoon, pre-monsoon, and monsoon seasons. After acid digestion, they were analyzed for metals using inductively coupled plasma mass spectrometer and assessed with index of geoaccumulation (Igeo), enrichment factor (EF) value, concentration factor (CF), and pollution load index (PLI). Principal component analysis (PCA) was employed to better comprehend the controlling factors of sediment quality. Considering all the seasons, the average concentrations of Fe, Cu, Cr, Pb, Mn, Ni, Zn, Co, and Ba in mg kg−1 was found to be 27,828 ± 12,772, 71 ± 59, 105 ± 78, 76 ± 62, 770 ± 489, 45 ± 28, 105 ± 47, 15 ± 6, and 738 ± 443, respectively. The Igeo, EF, CF, and PLI indices showed that the contamination of Pb and Cu was more serious than that of Ni, Zn, Co, and Ba whereas the presence of Fe, Mn, and Cr might be primarily from natural sources. The metal concentrations were in general higher in the pre-monsoon season; however, some of the metals were observed to be higher in the monsoon season. PCA outcome of three factors explained that 82.7 % of variance indicated both innate and human activities as contributing factors of metal profusion in Subarnarekha River. The overall study reveals moderately serious contamination of the sediments with metals in the Subarnarekha River predominantly in some locations under the anthropogenic influences like mining and industries.