MODIFICATION OF SOIL QUALITY NEAR A PULP AND PAPER MILL SMRITISIKHA PHUKAN and KRISHNA G. BHATTACHARYYA ∗ Department of Chemistry, Gauhati University, Guwahati 781014, Assam, India ( ∗ author for correspondence, e-mail: krishna111@sancharnet.in) (Received 9 July 2002; accepted 2 February 2003) Abstract. The Nagaon Pulp and Paper Mill (Assam, India) produces 100,000 tonnes of paper annu- ally 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 2 O 3 , Fe 2 O 3 , MnO, and TiO 2 showed a preferential accumulation of Al 2 O 3 , Fe 2 O 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. Keywords: heavy metals, physico-chemical properties, pulp and paper mill, soil quality 1. Introduction Pulp and paper mills discharge large volumes of brownish-coloured effluent con- taining chlorinated hydrocarbons, lignin and polymerized tannins (Crooks and Sikes, 1990; Reeve, 1991; Yan and Grant Allen, 1994; Diez et al., 1999). The effluent in- fluences the environment by imparting large biochemical oxygen demand (BOD), toxicity and colour. The solid wastes generated also have similar impacts. The toxicity is mostly due to tannins (Temmink et al., 1989), wood resins and chlorin- ated phenols (Walden et al., 1986). Particularly important is the presence of lignin and its derivatives, which are difficult to degrade due to the presence of strong intra-molecular C-C linkages. Due to their non-biodegradable nature, lignin and its derivatives are transferred to the neighbouring soil overlayers affecting soil qual- ity (Bajpai and Bajpai, 1994). The pulp mills using chlorine bleaching have been known to adversely affect the environment through discharge of effluent containing toxic polychlorinated dioxins, furans, and PCBs (Hodson et al., 1996; Schnell et Water, Air, and Soil Pollution 146: 319–333, 2003. © 2003 Kluwer Academic Publishers. Printed in the Netherlands.