Health status of the coastal waters of Mumbai and regions around

Abstract

The coastal marine environment of Mumbai, Maharashtra, India and regions around receives the domestic wastewater generated of around 1800 million litres per day (mld), mostly untreated. In addition, a large number of industries established in the drainage zones also contribute to pollution loads. These inputs have affected the water quality, sediment quality and biological characteristics of receiving waters to varying degrees. BOD in coastal water is often high and water is enriched in dissolved nitrogen and phosphorous compounds. Although the concentration of petroleum hydrocarbons (PHC) and phenols are high particularly in Thane creek, they are not alarming. The level of heavy metals such as Cr, Cu, Zn, Pb, Cd and Hg have enhanced, though marginally. The degraded water quality of coastal waters is also reflected in very high counts of pathogenic bacteria with their populations markedly decrease as the flood tide progresses. Adsorption and tranfer of pollutants to bed sediments by suspended particulate matter has increased the sediment burden of several pollutants in some areas. Degradation in water quality has induced marked alterations in community structure and population of phytoplankton, zooplankton and macrobenthos. The impact of anthropogenic pollutants decreases considerably from creek to offshore areas and is insignificant beyond 5 km from the shoreline