MODIFICATION OF SOIL QUALITY NEAR A PULP AND PAPER MILL

摘要

The Nagaon Pulp and Paper Mill (Assam, India) produces 100,000 tonnes of paper annually from bamboo. The mill is surrounded by a vast spread of agricultural land on all sides excepting the southern side, which is covered with hills and deep forests. The present study was undertaken with a view to assess the impact of the paper mill operations on the quality of the surrounding soil. Surface soil samples (0-15 cm depth) were collected in both dry and wet seasons over a four-year period from 19 points at different distances from the mill. The soil quality was determined with respect to a large number of representative physico-chemical properties. Estimation of the major oxides, e.g., SiO_2, Al_2O_3, Fe_2O_3, MnO, and TiO_2 showed a preferential accumulation of Al_2O_3, Fe_2O_3, and MnO in soil near the mill due to the dumping of fly ash and other solid wastes in the surrounding low lying land. Definite directional trends were observed not only with respect to these oxides, but also with the metals Ca, Mg, Na, and Pb, which decreased away from the mill. The soil pH had a tendency to turn alkaline near the mill owing to the discharge of highly alkaline effluent by the mill. The physical characteristics of the soil, viz., water holding capacity and bulk density increased with distance from the mill while the hydraulic conductivity had an opposite trend. N, P, K, B, Cl~-, and organic C contents of the soil had shown a rapid decreasing trend away from the mill indicating that the dumping of solid waste and discharge of nutrient-rich treated effluent had contributed to raised levels of these constituents near the mill.