Abstract
The pollution of river water and sediments by heavy metals has assumed serious problems due to their toxicity and accumulative behavior. The present study has been undertaken to assess the levels of heavy metals and the extent of pollution in the surface water and sediments from the Meghna river. Water and sediment samples were collected by the Standard Methods and, processed and analyzed for heavy metals using Flame Atomic Absorption Spectrophotometer (FAAS). The mean concentrations of heavy metal found in the river water were in the order of: Fe (1.0224 mg L-1) > Zn (0.0364 mg L-1) > Cr (0.0346 mg L-1) > Mn (0.0088 mg L-1) > Cd (0.003 mg L-1) and in the sediments in the order of: Fe (1281.416 mg kg-1) > Mn (442.596 mg kg-1) > Zn (79.021 mg kg-1) > Ni (76.116 mg kg-1) > Cr (31.739 mg kg-1) > Pb (9.4702 mg kg-1) > Cd (0.230 mg kg-1). Pb and Ni were found below detection limit in river water. Based on the findings, the Meghna river water can be considered as unpolluted with respect to Cd, Cr, Mn and Zn, whereas concentration of Fe was above the standard value according to recommended standard guidelines. According to Sediment Quality Guideline (USEPA, 1989), sediments were not polluted for Cd, Pb and Zn; moderately polluted for Cr and Mn and heavily polluted for Ni. The sediment geo-accumulation index (Igeo) values showed no pollution for most of sampling sites for all studied heavy metals. Pollution Load Index (PLI) values showed that all the studied sampling sites were not polluted and on the other hand mean Contamination Factor (CF) values showed low pollution for all measured heavy metals except Ni which indicated moderate pollution. This study can be used as reference to monitor the quality of water and sediments of the Meghna river.
Highlights
Rapid urbanization and industrial development during last decade have provoked some serious concerns in environment
This research reveals that the measured concentrations of Cd, Cr, Mn and Zn in the Meghna river water are lower but found lower but Iron (Fe) is higher than standard guidelines
According to USEPA (1989) sediment quality guideline, sediment are heavily polluted for Ni
Summary
Rapid urbanization and industrial development during last decade have provoked some serious concerns in environment. Distribution of heavy metals in water and sediments play a key role in detecting sources of heavy metal pollution in aquatic ecosystem (Singh et al, 2012). Their accumulation and distribution in sediments, water and environment are increasing at an alarming rate causing deposition and sedimentation in water reservoirs and affecting aquatic organisms as well (Mohiuddin et al, 2011). The composition of sediment sequences provides the best natural archives of recent environmental changes It acts as both carrier and potential sources of contaminants in an aquatic environment and can serve as a pool that can retain or release contaminants to the water column by various processes of remobilization (Ogbeibu et al, 2014).
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