Fractionation and bioavailability of Pb in municipal solid waste compost and Pb uptake by rice straw and grain under submerged condition in amended soil

Effect of addition of municipal solid waste compost (MSWC) on lead (Pb) content of submerged rice paddies was studied. Experiments were conducted during the three consecutive wet seasons from 1997 to 1999 on rice grown under submergence, at the Experimental Farm of Calcutta University, India. A sequential extraction method was used to determine the Pb fractions in MSWC and decomposed cow manure (DCM). Lead was significantly bound to the organic matter (60%) and Fe and Mn oxides in MSWC and DCM. Lead content (mg kg(-1)) in rice straw was higher than in rice grain. Lead bound with water soluble and exchangeable fractions in MSWC and DCM was best correlated with straw and grain Pb. Fe and Mn oxide bound Pb in both the organics also significantly correlated with straw and grain Pb content. Carbonate, organic matter bound and residual fractions of Pb in MSWC and DCM did not significantly correlate with Pb content in rice straw and grain metal. MSWC would be a valuable resource for agriculture if it can be used safely, but long-term field experiments with MSWC are needed to assess by regular monitoring of the metal loads and accumulation in soil and plants.