Balance of heavy metals in agroecosystems of the Meshchera lowland under irrigation with polluted water
2008
Mazhaisky, Yu.A. | Dorokhina, O.E., The A.N. Kostyakov All-Russia Research and Development Inst. of Hydraulic Engineering and Land Reclamation. Meshchera Branch, Ryazan (Russian Federation) | Kosheleva, N.E., Lomonosov Moscow State Univ. (Russian Federation)
The researches were carried out in 2002-2006 on the experimental watershed located in the Ryazan region. Migration and accumulation of Zn, Cd, Cu, Pb in the conditions of regular watering by polluted waters were under study. Concentrations of heavy metals (HM) were equivalent to maximum permissible concentration (MPC) or exceeded them in 2, 4, 8 and 15 times. As an experimental crops legumes and gramineous grasses, carrot and radish were used. They were grown on sod-podzolic sandy soils. Rainfall and irrigation waters were considered as sources of HM arrival in the soil. HM receipt from atmospheric precipitation was significant only for background (control) plots. The contribution of receipts from atmosphere in HM income balance was about 5-20% (in a variant with contamination 1 MPC) or about 1-5% (in the variant 15 MPC). About 94-98% Cu and Pb, 84% Zn and 59% Cd entered from atmosphere in background conditions. Carry-over of Cu with interflow was practically absent. Cu absorption by plants at the contamination level 4-15 MPC did not exceed 4% from its arrival. Carry-over of Cu with a plant biomass in background conditions reached 98.7% from its arrival. Zn was characterized by high motility, its leaching reached 80%, and accumulation in soil was observed only at concentrations HM in irrigation water 8 and 15 MPC. The differences among the studied crops in HM accumulation were revealed. The root crops accumulated HM most of all, the mixture from pea and oat is least of all. The HM content in crops and in soil has exceeded MPC in the first years after watering by polluted waters started. It was proposed to control of environment pollution on 2 directions: to reduce arrival of HM in agrolandscapes or to use the crops accumulating HM in a biomass for soil cleaning.
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