Long-term Effect of Irrigation with Treated Sewage Water on Soil Fertility and Accumulation of Heavy Metals in Soil

摘要

Effect of long-term irrigation with treated sewage water was studied on changes in soil pH, electrical conductivity, cation exchange capacity, organic carbon, available macro- and micro-nutrients and the contents of toxic heavy metals. The soils receiving treated sewage water for irrigation had lower pH than the adjacent control soils irrigated with tube-well water. There was an increase in organic carbon content and cation exchange capacity in treated sewage water irrigated soils in comparison to soils irrigated with tube-well water. Long-term irrigation of soils for the past 10 years with treated sewage water considerably raised the levels of available macro-nutrients (N, P, K and S) and DTPA-extractable micro-nutrients (Fe, Zn, Cu and Mn) over the nearby untreated soils. However, increased concentrations of toxic heavy metals (Cd, Cr, Ni and Pb) in sewage water irrigated soils suggest the need to enforce regulation on the long-term use of treated sewage water on the same fields for crop production.