SARASWAT et al: IMPACT OF BRASS AND ELECTROPLATING INDUSTRY WASTEWATER ON SOIL 957 Journal of Scientific & Industrial Research Vol. 66, November 2007, pp. 957-962 *Author for correspondence Tel: 91+05944 233 904; 91+09411159542 E-mail: raijpn@yahoo.com Impact of brass and electroplating industry effluent on some physico- chemical and biological properties of soil Shweta Saraswat, Saumyata Tewari and J P N Rai* Ecotechnology Laboratory, Department of Environmental Science, G B Pant University of Agriculture and Technology, Pantnagar 263 145 Received 22 March 2007; revised 10 July 2007; accepted 13 July 2007 A field study was conducted at three sites (S1-S3) of 500m longitudinal transect along the drain, where soil was irrigated by toxic metal rich brass and electroplating industrial effluent in suburban area of Moradabad, India. Spatial and seasonal variations of total heavy metal content in soil and their effect on physico-chemical and biological properties were studied in soil samples taken from 0-25, 25-50 and 50-75 cm soil depth. Except pH, all parameters were maximum in summer in surface soil at each site. Total metal content decreased with increasing distance from the effluent course. Physico-chemical values (pH, EC, C org , available N etc.) were found minimum at S1 and maximum at S3. Significant inhibition of microbial biomass C and N, respiration, dehydrogenase activity and microbial coefficient occurred in soils highly contaminated by heavy metals. There was a significant decrease in C mic /N mic ratio and an increase in metabolic quotient (qCO 2 ) with increasing metal concentration. Keywords: Enzymatic activities, Heavy metals, Industrial wastewater, Microbial activities, Soil pollution Introduction Industrial wastewater, often used for irrigation in the developing countries like India 1 , has aggravated soil pollution by toxic metals 2,3 , which are released into ground water or soil solution available for plant uptake 4 and also render land unsuitable for plant growth. Repeated use of wastewater reduces soil capacity to retain heavy metals. Exposure to toxic heavy metals 5,6 results in the reduction of microbial diversity and activities in the soil thereby impairing soil fertility status and plant growth 7-10 . This study reports impact of toxic metal rich wastewater on physico-chemical characteristics (pH, EC, organic carbon, available N, total heavy metal content) and biological properties (soil respiration, microbial biomass C and N, dehydrogenase activities etc.) of soil. Materials and Methods Experimental Site Field study was conducted along the downstream of Karula nala (drain), Moradabad, India. Drain contains effluent of brass and electroplating industries of the region 11 . Effluent characteristics were: pH, 6.7; total solids (TS), 3790; total dissolved solids (TDS), 2470; total soluble solids (TSS), 1320; COD, 3723; Zn, 55.56; Cu, 34.10; Ni, 10.35; Cr, 8.29; and Cd, 1.46 mg/l; and electrical conductivity (EC), 1.78 dSm -1 . Very often water flowing through drain is used for crop irrigation. The city has about 450 electroplating units, involving use of toxic chemical compounds (ammonium persulphate, copper and nickel sulphate, lead and floroborates), a variety of acids and metal salts etc. On an average, one electroplating unit discharges effluent at the rate of 2.5-3.0 kl/8 h. Soil Texture and Sampling Soil of experimental site is sandy loam (sand 60-80, silt 10-20 and clay 8-16%). Five random soil samples were collected from each of the three depths (0-25, 25-50 and 50-75 cm) at three sampling sites (S1, S2 and S3; distance from effluent channel 20, 200 and 500 m respectively) during summer (April 2006) and winter (December 2006). A monolith (15 cm x 15 cm x 25 cm) was dug at each site for the collection of soil samples. The samples were then placed in individual plastic bags and analyzed for physico-chemical and biological characteristics. Replicates of soil sample were mixed thoroughly, air dried, crushed and passed through a 2 mm sieve. Samples were kept in the dark at 4°C for biological analysis.