Evaluating toxic element contamination sources in groundwater bodies of two Mediterranean sites.

The Driver-Pressure-State-Impact-Response (DPSIR) framework is applied for assessing the pressures and impacts on groundwater bodies of two Mediterranean sites (Megara and Oropos-Kalamos basins). The study areas present joint driving forces (drivers) and pressures. The main driving forces in the areas studied mainly include geology, agricultural activities, and urban development, while the main pressures mainly include the weathering of ultramafic rock masses, application of agrochemicals, and groundwater abstractions for irrigation and drinking uses.

Mineral characterization of the biogenic Fe(III)(hydr)oxides produced during Fe(II)-driven denitrification with Cu, Ni and Zn.

The recovery of iron and other heavy metals by the formation of Fe(III) (hydr)oxides is an important application of microbially-driven processes. The mineral characterization of the precipitates formed during Fe(II)-mediated autotrophic denitrification with and without the addition of Cu, Ni, and Zn by four different microbial cultures was investigated by X-ray fluorescence (XRF), Raman spectroscopy, scanning electron microscopy equipped with energy dispersive X-Ray analyzer (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray Powder Diffraction (XRD) analyses. Fe(II)-mediated autotrophic denitrification resulted in the formation of a mixture of Fe(III) (hydr)oxides composed of amorphous phase, poorly crystalline (ferrihydrite) and crystalline phases (hematite, akaganeite and maghemite).

Effect of Cu, Ni and Zn on Fe(II)-driven autotrophic denitrification.

Fe(II)-mediated autotrophic denitrification in the presence of copper (Cu), nickel (Ni) and zinc (Zn) with four different microbial cultures was investigated in batch bioassays. In the absence of metals, complete nitrate removal and Fe(II) oxidation were achieved with a Thiobacillus-dominated mixed culture and Pseudogulbenkiania sp. 2002 after 7 d.

Influence of pH, EDTA/Fe(II) ratio, and microbial culture on Fe(II)-mediated autotrophic denitrification.

Fe(II)-mediated autotrophic denitrification with four different microbial cultures under different pH and EDTA/Fe(II) conditions was investigated in batch bioassays. Initially, the highest nitrate removal (72%) was achieved with an activated sludge inoculum. The use of pure cultures of Pseudogulbenkiania strain 2002 and Thiobacillus denitrificans resulted in a 55 and 52% nitrate removal, respectively.