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Soil quality indicators in lead mining and metalurgy area: II - Mesofauna and plants

The influence of soil management or the contaminant application to the soil, usually induce to a quicker response in the soil mesofauna than in other pedogenic properties; these organisms are therefore good environmental quality indicators. The aim of this study was to identify and quantify the organisms groups of the soil mesofauna and determine Pb and Zn contents in plants in the mining and metallurgy plant in Adrianópolis (PR),to originate biological indicators of the quality of these solis. At the selected locations the following contamination forms were analized: site 1 - reference (native wood); site 2 - residue incorporated in the profile; sites 3 and 6 - close to the chimneys of the plant, with potential import of particulate matter; site 5 - great waste volume covering the soil. Berlese funnels were utilized to collect samples from the 0 to 5 cm layer (20 funnels x 5 sites x 1 layer x 4 times = 400 samples). After the separation of the mesofauna, the organisms were selected and identified. Ants samples were microwave digested with concentrated HNO3 and the Pb, Cu, Ni and Zn contents were determined by inductively coupled plasma - atomic emission Spectrometry (ICP-AES). Plants from Poaceae family were collected in all sites and the Pb, Cu, Ni and Zn contents determined after nitric-perchloric digestion, using ICP-AES. The total organism number from the 21 identified groups and the Mesofauna Environmental Quality Index were not good indicators of the heavy metal contamination level of the soil. The quantity and distribution of isolated species proved more efficient for this purpose. The best environmental quality at site 1(natural Pb levels - control soil) was evidenced by the highest diversity of organism groups and occurrence of the representative groups Pseudoscorpiones, Mollusca and Isopoda in this soil. The groups Arachinida and Psocoptera were also considered good environmental indicators, with population increases at sites with higher heavy metals content (sites 2, 3 and 5), possibly because of the reduced occurrence of competitor/predator organisms. The heavy metal content in the individuals of the group of Formicidae was directly related to the soil Pb content extracted with 0.5 mol L-1 HNO3. In terms of heavy metal accumulation in native species, with exception of site 1, the soil had a phytotoxic effect of Pb and Zn on all species, suggesting that grazing should be banned.

biological indicators; environmental contamination; heavy metals; heavy metal fitotoxicity


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