MUD VOLCANOES FROM BANAT REGION (ROMANIA): THEIR ENVIRONMENT IMPACT

An assessment of the natural manifestations of fluids (gases, water) and solid phases (fine-grained sediments) from deep sediment layers of Banat area, in mud volcanoes (MVs) category is given. The total occurrence area of recent or ancient mud volcanoes in Fibis Valley is about 0.9 km(2). All the craters occur along the Fibis Valley, along a NNE-SSW direction, at an average altitude of 121m. They occur along an active fault system, acting as conduits for the migration of fluids. The main crater is Forocici Crater (FC), where the gas emissions include CO2, CH4, CO and H2S. Seven secondary craters are recorded, and two are temporarily active, having several seepages with gas and water eruptions. Fluid flows of mud volcanoes of the Fibis Valley have an important impact on atmospheric gas budget. The craters shape is generally irregular developing at soil level, with the exception of crater C2 (sub-circular shape) and Forocici Crater which has a gryphon type cone. Fe dominates the water samples collected at FC pool. Low concentrations of Cr, Ni and Zn were observed. Analyses of heavy metal concentrations of soil show wide variations. All concentrations of metal are low and below the maximum allowable limit. However, some samples show high concentrations of metals, such as those containing Fe, Pb and Cu. All examined soil and mud samples present a higher content of Fe (2144 mg/kg - 2585 mg/kg). Generally, heavy metal concentrations in soil do not exceed the allowable maximum values, except Pb (27.5 - 38.0 mg/kg d.s.), toxic for animals grazing growing in Fabis Valley. Salix cinerea L. which grows on the soil at the limit between the crater and Forocici Crater cone contains Fe (55.50 -80.00 mg/kg d.s.), Cu (2.74 - 4.50 mg/kg d.s.), Ni (0.15 mg/kg d.s.), Pb (1.35. mg/kg d.s.) and Zn (42.20 mg/kg d.s.). The mineralized fluids brought from deep layers control heavy metals concentration. From the substratum of Forocici Crater, we identified six species of diatoms (Gomphonema minutum (Agardh) Agardh, Pinnularia obscura Krasske, Geissleria acceptata (Hustedt) Lange-Bertalot & Metzeltin, Hippodonta linearis (Ostrup) Lange-Bertalot, Metzeltin & Witkowski, Stauroneis anceps Ehrenberg and Nitzschia solita Hustedt). These data sets represent a contribution to the understanding of mud volcanoes' output, of their influence on the environment and to the understanding of deep and shallow fluids in mud volcano systems.