Heavy Metals in the Anthropogenic Cycle of Elements

Abstract

The increasing entry or unnatural concentration of man-made substances in soils affects every level of the biosphere. At the molecular-ionic level, it is apparent in significantly increased contents of heavy metals in agro-ecosystems and biogeochemical cycles. This may not, yet, amount to pollution but increased concentrations are being found in farm products – so it is prudent to control the heavy metal content of soils and develop agricultural technologies that can reduce their concentration. A management strategy should include: (a) systematic monitoring of the content of heavy metals and categorization of background levels according to the soil’s buffering capacity, taking account of expected changes, current and possible soil degradation in particular; (b) ecological appraisal of agricultural technologies and prohibition of aggressive practices and chemicals; (c) adoption of biologically based practices and substitution of synthetic plant-protection products and fertilizers with biological products and manure; (d) augmenting the buffering capacity of the soil by increasing the content of organic matter and adjusting pH; and (e) special measures to reduce the impact of heavy metals, treatments that create geochemical barriers to the mobility of the elements (application of lime, gypsum, bentonite and farmyard manure) as well as cultivation of industrial crops.