Scholarly record

OCCURRENCE AND EVOLUTION OF HEAVY METALS AND AS POLLUTION IN WATERS AND VEGETABLES IN PLOVDIV – ASSENOVGRAD AREA

E. N. Pentcheva, N. Velitchkova, M. Karadjov

Abstract

The degree of heavy metal (+As) water and vegetable contamination due to mining and metallurgical activities in the studied area is evaluated in individual and integral aspects. 267 ground, surface and waste water samples, according to the proposed grid, were investigated for trace elements, 56 of them for 34 elements: Al, As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Zn, Hg, Be, B, V, Sn, Mo, Se, Ag, Te, Tl, Ti, U, Ca, Li, Mg, Sr, Bi, Ga, In, K, and Na. The analytical work is performed with inductively coupled plasma atomic emission spectrometer (ICP-AES) a Jobin Yvon ULTIMA 2 system, equipped with 1-m Czerny-Turner monochromator (practical spectral bandwidth is better than 5 pm from 160 nm to 320 nm and 10 pm for 320 nm – 800 nm) and 40.68 MHz ICP. The higher polluted ground waters with Pb, Cd and Cu are situated in the most endangered area around the plants in the site, analogous are the results for the Zn, Fe, Mn and As contamination, with a supplement pollution data for more distant points. Some Tl, Hg, Se, Sb are also established. The obtained and mapped data for 30 monitoring water points show remarkable seasonal variations of pollutant concentrations (until 3 orders for Pb and Zn). Important results are also obtained by the monthly phisico-chemical observation. Monitoring study assures evolution evidence. The dangerous effect of heavy metals like Pb, Cd, Cu, Zn becomes multiplied by their interactions with other pollutants such xenobiotics. Interesting results about the significant role of bacteria, concerning the migration and the detoxification of the metal pollutants after interaction and biotransformation are obtained and a possibility for bacteria based bioremediation of heavy metal and pesticide water pollution is suggested. Some exemplary results established by the vegetable investigations (of divided different parts) show that: 1) The heavy metal pollution depends strongly on the aerosol emissions from the metallurgical plants, mainly Pb and Cd; 2) The most important influence of the aerosol emissions is trended in the WS-S direction under the influence of the predominant wind; 3) Pb and Cd oxides or carbonates are strongly adsorbed or absorbed on the surface of the maize leaves (washing in ultrasonic bath); 4) These and other data (the difference between leaves and veins) show that As comes from the soil; 5) The pollution decreases between outside and inside maize leaves 3-10 times; 6) By carrots, pepper and maize conclusions for significant predomination of pollutants in leaves are confirmed; 7) Rizin leaves are accumulating Pb, Cd, Zn, As, about 3 times below are the concentrations in veins; 8) Heavy metal and As concentrations in walnuts, maize corns and carrots are in the norms. The hydrogeochemical study and monitoring carried out is especially important, presenting possibilities for limitation of the industrial and mining pollution and recovery of the environmental equilibrium. The knowledge about the metal behavior in water-soil system in evolution ensures the base for the 4-D Geographical Information System (GIS) and for the coupled hydrogeochemical-hydrodynamical modeling of the processes in the aim of forecast and control of the pollution dissemination. The investigations are financial supported by NATO Science for Peace Program in the frames of the Project NATO SfP 973 739 “WATMETAPOL”.

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