Distribution of nutrients and toxic metals in the Brahmaputra River Basin

Abstract

Sediments are important sinks for land derived contaminants, especially for toxic metals and have been widely used to identify sources of pollution, to evaluate its extent and to diagnose the environmental newlinequality of aquatic systems. The level of pollutants immobilized in the newlinesediment depends not only on the physical, chemical and biological newlineproperties of the sediment, but also on the background levels of the newlinepollutants. It is thus essential to understand the background newlineconcentrations since a river system will be used more and more intensely newlinefor effluent/sewage discharge and for dumping wastes. newlineUntil now almost no data have been reported on the organic matter, newlinenutrients and heavy metals in the sediments and biota of the Brahmaputra newlineBasin. These baseline data are also important in designing long term newline~nagement and conserv4tion policies of this as well as other similar large newlinetrop-ica 1 river bas ins. newlineThe present work broadly is an effort to evaluate the particulate newlineelement distribution summarising results of several field investigations. newlineIt is also an attempt to explain the composition of the bed sediment and newlinethe suspended particulates (SPM) in relation to source and in- situ newlineparticle production by use of interrelations between the SPM newlinecharacteristics and nutrient as well as trace element concentrations. Forthe newlinefirst time, a study of distribution of flux of metals and some newlineimportant nutrients have been attempted together for the newlineriver. With the help of important geochemical parameters newlineBrahmaputra newlinelike metals, newlinecarbon, phosphorous, nitrogen and other nutrients in particulates, sediment newline1 newlinesize distribution and mineralogy in the basin, distribution of organic newlinematters, toxic metals, nutrients and their fluxes have been attempted to newlineexplain. The spatial and seasonal variations of these elements were also newlineinvestigated. newlineThe main objective of the present study was to examine the nature newlineand the processes of distribution and transport of major heavy metals (Fe, newlineMn, Cu, Pb, Zn, Sr, Ni and Cd) and other nutrients (P, C