Speciation, accumulation of heavy metals in vegetation grown on sludge amended soils and their transfer to human food chain - A case study

The continuous use of heavy metal contaminated sewage sludge as a fertilizer can result in transfer and accumulation of toxic metals from sludge to soil. The subsequent uptake and accumulation of metals in the edible parts of vegetative tissue results in a direct pathway into the human food chain. Speciation study has great importance for monitoring the entry of heavy metals into the human food chain as these are associated in a variable manner in different phases (or species). To assess the extent of heavy metal contamination of soils and also of the vegetables grown on soil amended with sludge, speciation studies were carried out using BCR sequential extraction scheme proposed by European Commission. The vegetables that were grown on sludge amended agricultural fields were analyzed for toxic heavy metals to assess the extent of uptake of heavy metals by different plants. This study reflects the extent of contamination of soil and vegetation due to application of sludge as manure and element transfer to the human food chain.