Examining the heavy metal contents of an estuarine ecosystem: case study from Maharashtra, India

Estuarine ecosystems are not only physically and chemically dynamic, but also harbor unique and often specialist floral and faunal species. Nonetheless, they are subject to an increasing threat from existing human and projected climatic activities. This study examines the heavy metal contents of the Ulhas rivere stuary in Maharashtra, India - a biodiversity-rich and critically important ecosystem for native and migrant species. The drainages (within the catchment area) which supply water to the estuary were investigated to ascertain heavy metal levels, possibly resulting from anthropogenic activities. Concentrations of selected environmentally important heavy metals such as chromium (Cr), lead (Pb), nickel (Ni), copper (Cu), cadmium (Cd), zinc (Zn) and mercury (Hg) were measured using standard techniques. The findings reveal pre-occupying pollution levels that constitute a significant threat to both terrestrial and aquatic species dependents on the estuary. The abundance of heavy metals in the estuary was in the order of Pb > Ni > Cr > Cu > Zn > Hg > Cd (Pb between 0.018 mg/l to0.039 mg/l; Cd 0.006 mg/l to 0.009 mg/l). The contamination of heavy metals (often toxic over the recommended levels) was found to be high at sampling sites under the direct influence of human habitats and industries. The finding of this study not only adds to the available information regarding the status of the estuary, but also highlights the critical need to implement targeted strategies towards management and protect this vital ecosystem.