Solid waste is now one of the major environmental problems of mega-cities. Thousands of tonnes of waste is generated every day, requiring a large land area for its disposal. An integrated solid waste management plan has been discussed including various components, for example waste minimization, material recovery, waste processing and transformation, and its disposal on land. Leachate control and gas collection at landfills have also been discussed.
Bernadette,Q; Daniel,C; Bernard,R; Thanh,TP; Gagnon,P; Benoir,F (1999): Sources and fluxes of Mercury in the St. Lawrence River. Environmental Science & Technology, 33(6): 840-849.
A mass balance approach, based essentially on the reconstruction of daily fluxes and circumscribed by strict error calculations, was designed to quantify the main mercury sources for the St. Lawrence and its tributaries, which constitute a large river system. High-frequency samplings were performed over an 18-month period (1995-1996) at the main water inputs and the mouth of the river. Minor tributaries and the Montreal effluent were also sampled This strategy allowed models to be obtained that relates mercury concentrations in solution and in particles to the hydrological regime. The calculated budget was balanced relative to the calculated errors of the estimates. Gross mercury export from the river was found to be 5.9 kmol/yr (73% as particulate). Tributaries and internal erosion of the river contributed equally for a total of 15% of this gross load, whereas the Upper St Lawrence River, which is almost exclusively composed of Lake Ontario waters, accounted for less than 10%, and inventoried anthropogenic point sources accounted for about 5%. Dissolved mercury was mainly from north shore tributaries, and particulate mercury was largely from erosion of the river bed and banks. On the basis of the present results as well as estimates of atmospheric deposition from the literature it can be inferred fat at least 88% of deposited mercury was retained in the watersheds.
Bhattacharyya,KG; Deka,DK; Sarma,C (1999): Distribution of heavy metals in surface water and bed sediments of a few drinking water sources in Guwahati. Indian Journal of Environmental Protection, 19(2): 110-118.
The study reports the distribution pattern of a few heavy metals, namely Fe, Mn, Cu, Zn, Cd, Pb, Cr, and Co in surface water and bed sediments of a few traditional drinking water sources ( 4 Ponds, 3 ring - wells and one natural reservoir ) in Guwahati City, India. The sampling and analysis were carried out on seasonal basis over a three year period. The metal contents have been found quite appreciable for both water and sediment.