Photochemical degradation of methylparathion in the presence of humic acid

Photochemical degradation of methylparathion (O,O,-dimethyl O-4 nitrophenylphosphorothioate) in the presence of humic acid between pH 2 and 7 was monitored by differential pulse polarography. Humic acid was not electro-active under the experimental conditions used in this study. Only the pesticide and its main degradation product at pH 2 exhibited polarographic signals. Photolysis of methylparathion in acid media was sensitized by humic acid since the pesticide did not degrade in the absence of this compound. Methylparathion degradation in the presence of humic acid was observed at each of the studied pHs. The reaction was first-order with rate constant values ranging from 2 x 10(-3) to 6.3 x 10(-3) min(-1).     

Cadmium stress alters gene expression of DNA mismatch repair related genes in Arabidopsis seedlings

Cadmium (Cd) is a non essential element, and is a widespread environmental pollutant. Exposure to Cd can result in a variety of adverse health effects in plant and humans. In the current study, Arabidopsis seedlings were used as a bio-indicator of Cd pollution. Seedlings were grown on MS media containing 0-6.0 mg L(-1) Cd for 18 days, and the gene expression patterns were used to link increased Cd exposure with progressive biological effects. Reduction of total soluble protein content in shoots of the Arabidopsis seedlings occurred with increase in Cd concentrations. For the gene expression patterns, seven genes known to be involved in cell division and DNA mismatch repair (MMR) system were investigated by semi-quantitative RT-PCR, and normalized using 18S rRNA gene expression. Expression of the proliferating cell nuclear antigen 2 (atPCNA 2), MutS 3 homolog (atMSH 3) and MutL1 homolog (atMLH1) genes in shoots of Arabidopsis was strongly induced by exposure to 0.75 mg L(-1) Cd, but were repressed by other Cd concentrations whereas exposure to 0.75-6 mg L(-1) of Cd resulted in a decreased expression of atPCNA1, atMSH 2, 6 and 7 genes independently of any observable biological effects, including survival, fresh weight and chlorophyll level of shoots. This work demonstrated that specific gene expression changes could serve as useful molecular biomarkers indicative of Cd exposure and related biological effects.     

Dioxins in adipose tissue of women in Southern Spain

Seventeen polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were quantified in adipose tissue samples of non-occupationally exposed women living in Southern Spain. Geometric mean levels of sum of congeners and WHO(PCDD/F)-TEQ(2005) were 410 and 17.9pgg(-1) fat, respectively. Among PCDDs, octachlorodibenzo-p-dioxin (OCDD) showed the highest concentration with a mean value of 265pgg(-1) fat, followed by 1,2,3,6,7,8-HxCDD (49.3pgg(-1) fat) and 1,2,3,4,6,7,8-HpCDD (45.2pgg(-1) fat). These three congeners were responsible for around 90% of the sum of all PCDD/F congeners in adipose tissue. The geometric mean 2,3,7,8-TCDD value was 1.87pgg(-1) fat. 2,3,4,7,8-PeCDF (8.43pgg(-1) fat) showed the highest concentration among the PCDFs, followed by 1,2,3,4,7,8-HxCDF (4.17pgg(-1) fat) and 1,2,3,6,7,8-HxCDF (3.28pgg(-1) fat), and these three congeners were responsible for 4% of the sum of all studied PCDD/F congeners in adipose tissue and 76% of the sum of ten PCDFs. 1,2,3,7,8,9-HxCDF was the only congener not quantified in any sample, while 1,2,3,4,7,8,9-HpCDF, 1,2,3,7,8-PeCDF, OCDF and 2,3,7,8-TCDF were found in 5, 16, 16 and 19 samples, respectively. All other congeners were quantifiable in all 20 samples. Congeners contributing most to the WHO(PCDD/F)-TEQ(2005) were 1,2,3,7,8-PeCDD (31.6%), 1,2,3,6,7,8-HxCDD (28.3%) and 2,3,4,7,8-PeCDF (14.6%). The body burden of log-transformed WHO(PCDD/F)-TEQ(2005) levels increased with age (B=0.02; 95% CI=0.01, 0.03; p=0.02). Although these adipose tissue PCDD/F levels are similar to previously published findings in Spain and other European countries, further research is needed to determine trends in the exposure of women to these chemical residues.     

Lethal and sublethal effects of the pyrethroid, bifenthrin, on grass shrimp (Palaemonetes pugio) and sheepshead minnow (Cyprinodon variegatus)

This study investigated the lethal and sublethal effects of the pyrethroid insecticide bifenthrin on adult and larval grass shrimp, Palaemonetes pugio, and adult sheepshead minnows, Cyprinodon variegatus. The effects were determined by conducting 96-h aqueous static renewal tests and 24-h static tests with sediment. Oxidative stress biomarkers, lipid peroxidation, glutathione, and catalase were also assessed. The 96-h aqueous LC50 value for adult shrimp was 0.020 microg/L (95% CI: 0.015-0.025 microg/L) and for larval shrimp was 0.013 microg/L (95% CI: 0.011-0.016 microg/L). The 96-h aqueous LC50 for adult sheepshead minnow was 19.806 microg/L (95% CI: 11.886-47.250 microg/L). The 24-h sediment LC50 for adult shrimp was 0.339 microg/L (95% CI: 0.291-0.381 microg/L) and for larval shrimp was 0.210 microg/L (95% CI: 0.096-0.393 microg/L). The oxidative stress assays showed some increasing trends toward physiological stress with increased bifenthrin concentrations but they were largely inconclusive. Given the sensitivity of grass shrimp to this compound in laboratory bioassays, additional work will be needed to determine if these exposure levels are environmentally relevant.     

Rates of spread of <Emphasis Type="Italic">Rosa rugosa</Emphasis> (Japanese Rose) determined by GIS on a coastal sand-dune system in Northwest England

The invasive non-native shrub Rosa rugosa (Japanese Rose) is well-established in many northwest European countries where, especially on coastal sand-dunes, it forms large dominant stands with adverse effects on semi-natural vegetation and biota of high conservation status. Its recent increase in England’s largest dune system on the Sefton Coast in north Merseyside led to an investigation into its rate of spread. Using digitised aerial photographs and GIS methodology, sample patches of old-established R. rugosa were found to have grown in area by an average of 22 % per annum between 1989 and 2013. This rate of increase is comparable to that found in Denmark and higher than reported for several other woody plants in coastal dunes. In the absence of management, R. rugosa could soon dominate large areas on the Sefton Coast, with serious consequences for amenity and the nature conservation interest of the dune system.     

Removal of Eu3+, Ce3+, Sr2+, and Cs+ ions from radioactive waste solutions by modified activated carbon prepared from coconut shells

As a biomass agricultural waste material, coconut shells were used for the preparation of high-quality modified activated carbon. Chemical modification of the surface of the prepared activated carbon is done by oxidation using H₂O₂ and HNO₃, respectively. The surface area and pore volume of the coconut shells activated carbon are increased by the chemical modification, and followingly the removal of the metals is improved. The structural morphology and composition of the modified activated carbon coconut shells (MACCS) were evaluated by Fourier transform infrared (FTIR) spectra, thermogravimetric analysis–differential thermal analysis (TGA-DTA), scanning electron microscope (SEM), X-ray diffraction (XRD), surface area analysis (SAA), X-ray fluorescence (XRF), and carbon, hydrogen, nitrogen, and sulfur (CHNS) elemental analysis. The prepared MACCS has reasonably good chemical stability. The influence of solution pH, contact time, adsorbent dosage, adsorption temperature, initial metal concentrations, and interfering ions on the adsorption performance of the investigated ions onto the prepared sorbent was examined by a batch method. The selectivity sequence for sorption of Eu³⁺, Ce³⁺, Sr²⁺, and Cs⁺ ions on MACCS was found to be Eu^3+?>?Ce^3+?>?Sr^2+?>?Cs⁺. The saturation capacities of MACCS for the studied metal ions were found to be 136.84, 85.55, 69.85, and 60.00?mg?g^?1 for Eu³⁺, Ce³⁺, Sr²⁺, and Cs⁺ ions, respectively. The thermodynamic parameters, ΔH°, ΔS°, and ΔG° were also evaluated.