Ion transport by the river siang Arunachal Pradesh with special reference to distribution of heavy metals in water and sediements

Abstract

ION TRANSPORT BY THE RIVER SIANG (ARUNACHAL PRADESH) WITH SPECIAL REFERENCE TO DISTRIBUTION OF HEAVY METALS IN WATER AND SEDIMENTS The river Siang, which is one of the major river systems of Arunachal Pradesh, has its origin in the Chama-Yung-Dung Glacier in Tibet at the Kailas range of the Himalayas. The river Siang is known as Tsangpo in its upper course in Tibet, which has given the districts of East, West and Upper Siang their names. After the river breaks through mountain ranges along the international border and makes its way into Indian territory east of Gelling in Upper Siang district, it flows south-south east until it takes a southerly turn. At Pangin, the river has bent towards the south east and has run up to Pasighat where it again sharply turns due south. Finally, the Siang descends down into the plains of Assam and meets the combined flow of the Dibang and the Lohit near Kobo in Jonai sub-division of Assam and becomes the mighty Brahmaputra River. Pasighat, a small town on the banks of the river Siang (upper course of the river Brahmaputra) in Arunachal Pradesh, was a neat and clean town a few years back, but has been rapidly converted into a fast-growing urban center with large quantity of municipal garbage and domestic waste produced and dumped every day. The wastes ultimately find their way to the river Siang affecting the pristine quality of the river water. Moreover, the hilly terrain through which the river Siang flows down contains rich mineral deposits such as limestone, sulphides, ferrous minerals, etc. Weathering process may continually bring down the ions constituting these minerals into the river. Toxic heavy metals may also find their way to the aquatic environment from agricultural runoff, from leaching of metals from garbage and solid waste dumps and from animal and human excretion. Unabated deforestation along the banks of the river and soil erosion is changing the characteristics of the river continuously. The people residing downstream depend on the water of this river for all...