Saturday, 15 July 2006

Heavy Metals in Soil-Plant System in a City with Non-Ferrous Ores Extraction and Processing Industry.

Radu LACATUSU1, Anca Rovena Voiculescu2, Beatrice Kovacsovics2, Mihaela Lungu2, Iuliana Gabriela Breaban1, Constantin Rusu1, and Alexandru Bretan3. (1) "AL.I.Cuza" University IASSY, B-dul Carol I nr.20A, IASSY, Romania, (2) Research and Development National Institute for Soil Science, Agrochemistry and Environment Protection-RISSA, B-dul Marasti 61, Bucharest, Romania, (3) Soil Survey and Soil Testing Office, Baia Mare, Romania

In the northwest part of Romanian territory, at the foot of the Ignis-Oas mountains, there are Baia Mare, city with 150 thousands inhabitants, and a strongly non-ferrous ores extraction and processing industry. Mining activity, floating of ores and extraction in the smelting of chemical non-ferrous elements, has been intensively practicing, since XIXth Century. As consequence of this activity contamination and pollution of environment with heavy metals have been happened. The pollution intensity was directly proportional with magnifying of these activities, up to maximum level, in the second half of the XXth Century, especially. Among investigated heavy metals, Cd, Cu, Pb and Zn proved to be pollutants, reaching contents levels up to 16 mg Kg-1 (Cd), 5385 mg Kg-1 (Pb), and 2695 mg Kg-1 (Zn). These values outrun by 5.5 times (Cd), 4.5 times (Cu), 53 times (Pb) and 9 times (Zn) the maximum allowable limits. The native acid reaction of these soils, generally maintained, has been contributed to these chemicals compounds mobilization in soil. Heavy metals mobility was made obvious by extraction with CH3COONH4-EDTA solution at pH=7.0. The content values were up to some times higher than the maximum allowable level in soil solution that could permit a normal plants growth. The fractioning of heavy metals in soil established that from the total content of heavy metals, determined in the 0-20 cm layer, 18-24% are in soil solution, and, 18-21% in an exchangeable form. The both forms contribute directly to plants nutrition. The penetration depth in soil of heavy metals is different, varying between 60 and 100 cm. For establish the pollution intensity connected with using soil type, urban soils were grouped in three categories: park areas, along the streets areas, and gardens for vegetables and fruits. Urban soil pollution intensity established according to the value of contamination / pollution index, shows a Cd, Cu and Pb severe pollution in soils of park areas. Pb pollution was very severe in the soils along the streets and of gardens for vegetables and fruits. Finally, Zn pollution was moderate in soils from park areas and those from along streets, but severe in soils from gardens for vegetables and fruits. Between heavy metals contents in vegetables garden soils and the contents of the same chemical elements in some edible parts of vegetables (salad, carrot, onion, tomato, cucumber) direct proportionality relations, that attesting the certain plants contamination with heavy metals, were established.

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