Influence of suspended clay minerals and humic matter on the solid phase extraction efficiency of selected pesticides from water

The purpose of this investigation was to determine the influence of humic acids (HA) and Ca-montmorillonite (CaM) on the solid-phase extraction (SPE) efficiency of atrazine, alachlor and alpha-cypermethrin from water samples at various pH-values. The nature and intensity of binding of the studied pesticides to CaM were determined by X-ray diffraction analysis and termogravimetric analysis (TGA) test. The studied pesticides eluted from discs were analysed by thin-layer chromatography (TLC). The effects of CaM and humic acid were generally pH-dependent and acted independently in extraction efficiency influence. Lower recovery of pesticides was observed at higher pH values when CaM was > or =0.1 g and was attributed to greater dispersion of clay, increased surface area and subsequent adsorption. Concentrations of dissolved organic carbon (DOC) in humic acid had less effect on the extraction efficiency when water was at pH 8 compared to water at pH 2, which was probably due to greater nonpolar interactions of the pesticides to the charge-neutralized humic acid molecule.     

Impact of a severe flood on large-scale contamination of arable soils by potentially toxic elements (Serbia)

Environmental Geochemistry and Health - Extreme flooding in May, 2014 affected the sub-catchments of six major rivers in Serbia. The goal of the study was to evaluate the contents of potentially...     

Uptake,distribution and loss of Cr in the crab Xantho hydrophilus

Uptake of ⁵¹Cr(III) is faster than uptake of ⁵¹Cr(VI), but it occurs mainly on the surface of the animals. Steady state is attained after 28 d. The resulting concentration factor is about 200. Although the uptake of ⁵¹Cr(VI) is slower, it is more intensively distributed into the organs and tissues of the animals. Steady state was not attained during the experiments (35 d); the highest concentration factor reached was about 10. The uptake of both ⁵¹Cr(III) and ⁵¹Cr(VI) seems to be passive. For both chemical forms of chromium, the loss rate is inversely proportional to the exposure time. When the uptake lasted longer, owing to the distribution of Cr(VI) into the organs and tissues, the loss rate of Cr(III) is somewhat faster relative to the loss rate of ⁵¹Cr(VI). The opposite is the case when the uptake of both forms lasts only two days. On the basis of the distribution and loss experiments, we argue that hexavalent chromium in living organisms is reduced to the trivalent form and then complexed with organic molecules.     

Evaluation of the genotoxic and cytochrome P450 monooxygenase-inhibitory potential of Dicuran on procaryotic and eucaryotic test systems

The effect of the herbicide Dicuran 500 FL (formulated product) on the phenotypical and genotypical changes in procaryotic and eucaryotic organisms was investigated using short-term tests for detecting genotoxins. Since pesticides discharged in the water environment can modulate the mixed-function monooxygenases (MFO) detoxification system of water organisms, the in vivo and in vitro effects of Dicuran on hepatic cytochrome P450 (cyt P450) monooxygenase activities were also examined in juvenile carp (Cyprinus carpio L.). By measuring the activities of MFO in experimental carp exposed to Dicuran an attempt was made to establish whether Dicuran could be bioactivated by MFO into ultimate mutagens. Our results on the bacterial strains Salmonella typhimurium TA100 and TA98 show that Dicuran does not possess either mutagenic or premutagenic characteristics. The micronucleus test on the erythrocytes of experimental carp did not establish any clastogenic effect either. However, Dicuran significantly inhibited the MFO activity of 7-ethoxyresorufin-O-deethylase (EROD) and benzo[a]pyrene monooxygenase (BaPMO) in the liver of experimental carp in vitro, as well as in in vivo conditions. These findings demonstrate the potentially damaging effect of Dicuran on the xenobiotic metabolizing enzyme systems of fish, and suggest the applicability of described methods for the prediction of the ecotoxicological significance of the presence of pesticides in the water environment.     

Metal contamination recorded in the sediment of the semi-closed Bakar Bay (Croatia)

This study presents metal levels in the sediments of the Bakar Bay, with its main goal to evaluate recent anthropogenic influence, as well as over previous decades. Sediment profiles at 7 sampling points were taken. Chemical contents in bulk sediment were obtained using ICP, ICP-MS, and AAS methodologies, and 20 most significant elements were presented. Concentrations of selected elements were evaluated by factor statistical analyses to identify their source. Also, metal enrichment factor and geoaccumulation index were calculated, and spatial distribution maps for three sediment layers were constructed. Measured metal concentrations in sediment were compared with concentrations in other sediments from the Adriatic Sea. In addition, a set of sediment quality guidelines were also applied in order to predict the probability of adverse biological effects on the benthic community: This was found not to be very serious. Factor analysis clearly demonstrates the segregation between metals of natural origin resulted from soil and bedrock weathering (Li, Al, Cr, Sc), and with two anthropogenic sources originating from the city of Bakar and bulk cargo terminal (Hg, Pb, Zn, Ag, Sn, and Fe). Mercury (max 0.65 μg g^?1) is found to be the heaviest contaminant, followed by lead (max 71.5 μg g^?1), copper (89.3 μg g^?1), and zinc (156 μg g^?1). However, this study shows that Bakar Bay is considerably less polluted with toxic metals than it was believed.     

Metals in the sediment and liver of four fish species from different trophic levels in Tisza River,Serbia

In aquatic environments metals originate from various natural and anthropogenic sources. The degree of contamination in fish tissues depends on the pollutant, fish species, their mode of feeding, sampling site and trophic level. This study presents concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sr and Zn in sediment and liver of four ecologically different fish species: piscivorous northern pike (Esox lucius L.), benthivorous sterlet (Acipenser ruthenus L.) and silver bream (Brama brama L.), and omnivorous common carp (Cyprinus carpio L.). Fish were caught at four sites along the stretch of the River Tisza in Serbia during October 2010. The concentrations of metals have been assessed using the inductively coupled plasma – optical emission spectrometry. Results revealed that metals with the highest values in sediment and fish samples were Al and Fe, respectively and sometimes concentrations of Zn are in the same order of magnitude as Fe concentrations. The highest concentration of metals was recorded in omnivorous common carp.