Search results for "Water pollutant"
showing 10 items of 566 documents
Combined Theoretical and Experimental Study of the Photophysics of Asulam
2013
The photophysics of the neutral molecular form of the herbicide asulam has been described in a joint experimental and theoretical, at the CASPT2 level, study. The unique π → π* aromatic electronic transition (f, ca. 0.5) shows a weak red-shift as the polarity of the solvent is increased, whereas the fluorescence band undergoes larger red-shifts. Solvatochromic data point to higher dipole moment in the excited state than in the ground state (μ(g)μ(e)). The observed increase in pKa in the excited state (pKa* - pKa, ca. 3) is consistent with the results of the Kamlet-Abboud-Taft and Catalán et al. multiparametric approaches. Fluorescence quantum yield varies with the solvent, higher in water (…
Effects of activated carbon ageing in three PCB contaminated sediments: Sorption efficiency and secondary effects on Lumbriculus variegatus.
2015
The sorption efficiency and possible secondary effects of activated carbon (AC) (o 63-200 μm) was studied with Lumbriculus variegatus in three PCB contaminated sediments applying long AC-sediment contact time (3 years). AC amendment efficiently reduced PCB bioavailability as determined with both, L. variegatus bioaccumulation test and passive samplers. However, dose related secondary effects of AC on egestion rate and biomass were observed (applied doses 0.25% and 2.5% sediment dry weight). The sorption capacity and secondary effects remained similar when the experiments were repeated after three years of AC-sediment contact time. Further, transmission electron microscopy (TEM) samples reve…
Responses of Lumbriculus variegatus to Activated Carbon Amendments in Uncontaminated Sediments
2012
Activated carbon (AC) amendment is a recently developed sediment remediation method. The strong hydrophobic organic contaminant sorption efficiency of AC has been shown in several studies, but effects on benthic organisms require more investigation. The AC induced effects on egestion rate, growth and reproduction of Lumbriculus variegatus were studied by applying bituminous coal based AC in three different particle size fractions, namely <63 μm (90%, AC(p)), 63-200 μm (AC(m)) and 1000 μm (AC(g)), to natural uncontaminated (HS) and artificial sediment (AS). Egestion rate, growth and reproduction decreased with increasing AC concentration and finer AC particle fractions, effects being stronge…
Using the critical body residue approach to determine the acute toxicity of cadmium at varying levels of water hardness and dissolved organic carbon …
2011
Abstract The linkage between acute adverse effects of cadmium and internal cadmium levels were investigated for the oligochaete worm Lumbriculus variegatus in water at varying degrees of hardness and two different dissolved organic carbon (DOC) concentrations. The LC50s for the effect of cadmium on the survival of the worms greatly differed depending on water hardness and DOC. We found less variability in internal metal toxicity metrics (lethal residue; LR50s) than in external toxicity metrics (lethal concentration; LC50s): LC50s varied from 2.4 to 66.1 μmol/L, while LR50s varied only from 226 to 413 μmol/kg wet weight. The cadmium body burden appeared to be independent of exposure conditio…
Manganese overload affects p38 MAPK phosphorylation and metalloproteinase activity during sea urchin embryonic development.
2014
Abstract In the marine environment, manganese represents a potential emerging contaminant, resulting from an increased production of manganese-containing compounds. In earlier reports we found that the exposure of Paracentrotus lividus sea urchin embryos to manganese produced phenotypes with no skeleton. In addition, manganese interfered with calcium uptake, perturbed extracellular signal-regulated kinase (ERK) signaling, affected the expression of skeletogenic genes, and caused an increase of the hsc70 and hsc60 protein levels. Here, we extended our studies focusing on the temporal activation of the p38 mitogen-activated protein kinase (p38 MAPK) and the proteolytic activity of metalloprot…
Activation of MAP kinase signaling pathway in the mussel Mytilus galloprovincialis as biomarker of environmental pollution
2010
Stimulation of MAP kinase signal transduction pathway by various stressful stimuli was investigated in the marine bivalve Mytilus galloprovincialis. Analyses were performed in animals exposed in laboratory to selected pollutants and in mussels collected in winter and summer along the eastern Adriatic coast (Croatia). Effects of oxidative stress, induced by tributyltin, hydrogen peroxide and water soluble fraction of diesel fuel on the activation/phosphorylation of the three Mitogen-Activated Protein Kinases (MAPKs) p38, JNK and ERK using a newly developed ELISA procedure were evaluated. MAP kinase activation was analyzed 1 h after exposure of mussels to chemical agents, and after recovery p…
In vitro effect of cadmium and copper on separated blood leukocytes of Dicentrarchus labrax.
2013
The immunotoxic effects of heavy metals on blood leukocytes of sea bass (Dicentrarchus labrax) were examined. The cells, separated by a discontinuous Percoll-gradients, were exposed in vitro to various sublethal concentrations of cadmium and copper (10(-7) M, 10(-5) M, and 10(-3) M) and their immunotoxic effect was then evaluated by measuring neutral red uptake, MU assay, DNA fragmentation and Hsp70 gene expression. First of all, we demonstrated that the cells treated in vitro could incorporate Cd and Cu. A relationship between heavy metal exposure and dose-time-dependent alterations in responses of leukocytes from blood was found for both metals, but copper was more immunotoxic than cadmiu…
An overview of the methods used in the characterisation of natural organic matter (NOM) in relation to drinking water treatment
2010
Natural organic matter (NOM) is found in all surface, ground and soil waters. During recent decades, reports worldwide show a continuing increase in the color and NOM of the surface water, which has an adverse affect on drinking water purification. For several practical and hygienic reasons, the presence of NOM is undesirable in drinking water. Various technologies have been proposed for NOM removal with varying degrees of success. The properties and amount of NOM, however, can significantly affect the process efficiency. In order to improve and optimise these processes, the characterisation and quantification of NOM at different purification and treatment processes stages is important. It …
Detection of a synthetic sex steroid in the American crocodile (Crocodylus acutus): Evidence for a novel environmental androgen
2017
Endocrine-disrupting contaminants (EDC's) are well known to alter sexual differentiation among vertebrates via estrogenic effects during development, particularly in organisms characterized by temperature-dependent sex determination. However, substances producing androgenic effects typically lack potency when tested in laboratory settings and are virtually unstudied in field settings. Here, we assay levels of a synthetic androgen, 17a-methyltestosterone (MT), in a heavily male-biased population of American crocodiles in the Tempisque River Basin of Costa Rica based on the recent hypothesis that this chemical is an EDC in developing crocodilian embryos. The presence of MT was documented in a…
Polychlorinated diphenyl ethers, dibenzo-p-dioxins, dibenzofurans and biphenyls in seals and sediment from the Gulf of Finland.
1997
Polychlorinated diphenyl ethers (PCDEs), 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) were analyzed in seals from the Gulf of Finland and in sediments from the Gulf of Finland and near Gotland. The sediments included one surface core from both sampling sites. The seal material consisted of 14 ringed seals and 6 grey seals that all were found dead and examined for pathology. The main aims were to scrutinize levels and patterns of PCDEs for the first time in seals from the Baltic Sea and to estimate whether chlorinated compounds mentioned have an influence on an exceptional high mortality that occurred among ring…