Heathperry1656

8 to 9.3), dominantly due to the humic acid contribution. By modeling the practical Cd remediation scenarios, the enhanced Cd complexation performance of HS after SCE treatment was observed even at low pH values (pH = 5) or insufficient TOC content (TOC = 50 mg/L).Total concentrations of hydrophobic organic contaminants (HOCs) in sediment present a poor quality assessment parameter for aquatic organism exposure and environmental risk because they do not reflect contaminant bioavailability. The bioavailability issue of HOCs in sediments can be addressed by application of multi-ratio equilibrium passive sampling (EPS). In this study, riverbed sediment samples were collected during the Joint Danube Survey at 9 locations along the Danube River in 2013. Samples were ex-situ equilibrated with silicone passive samplers. Desorption isotherms were constructed, yielding two endpoints pore water (CW0) and accessible (CAS0) concentration of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers in sediment. CW0 concentrations of DDT and its breakdown products exhibited elevated levels in the low Danube, with the maximum in the river delta. Other investigated HOCs did not show any clear spatial iver catchments.Pyrethroids are an important class of insecticides, and thousands of tons of these compounds are used in the United States every year. This study characterized exposures to pyrethroids and assessed demographic, socioeconomic, and lifestyle factors that modulate pyrethroid exposure using data from the National Health and Nutrition Examination Survey (NHANES) 2007-2012, a nationally representative survey of the non-institutionalized population of the United States. Urinary levels of commonly used biomarkers of pyrethroid exposure, including 3-phenoxybenzoic acid (3-PBA), 4-fluoro-3-phenoxybenzoic acid (F-PBA), and cis-dibromovinyl-dimethylcyclopropane carboxylic acid (DBCA), were determined by liquid chromatography-tandem mass spectrometry. The detection rate of 3-PBA, a nonspecific metabolite of several pyrethroids, was 78.1% in adults (N = 5233) and 79.3% in children (N = 2295). The detection rates of all other pyrethroid metabolites were less then 10%. The median urinary level of 3-PBA in adults was 0.47 μg/L (interquartile range, 0.14-1.22 μg/L). For children, the median urinary level was 0.49 μg/L (interquartile range, 0.17-1.29 μg/L). Age, gender, family income-to-poverty ratio (PIR), levels of physical activity, alcohol intake, and body mass index were associated with 3-PBA levels in adults. In children, age, gender, race/ethnicity, and PIR were associated with 3-PBA levels. 3-PBA levels also differed significantly across NHANES cycles, with higher levels observed in NHANES 2011-2012. Geometric mean 3-PBA levels in U.S. adults were 0.41 μg/L in NHANES 2007-2008, 0.41 μg/L in NHANES 2009-2010, and 0.66 μg/L in NHANES 2011-2012. In U.S. children, geometric mean 3-PBA levels were 0.40 μg/L in NHANES 2007-2008, 0.46 μg/L in NHANES 2009-2010, and 0.70 μg/L in NHANES 2011-2012. These results demonstrate that pyrethroid exposures remain a current environmental health concern and lay the foundation for further preclinical and epidemiological studies assessing human health risks associated with pyrethroids.Tropospheric ozone (O3) impairs physiological processes of plants while nitrogen (N) deposition may cause imbalances in soil N and other nutrients such as phosphorus (P) suggesting an increase of P demand for plants. However, the combined effect of O3, soil N and P on isoprene emission from leaves has never been tested. see more We therefore examined isoprene emission in leaves of Oxford poplar clone exposed to O3 (ambient, AA [35.0 nmol mol-1 as daily mean]; 1.5 × AA; 2.0 × AA), soil N (0 and 80 kg N ha-1) and soil P (0, 40 and 80 kg P ha-1) in July and September in a Free-Air Controlled Exposure (FACE) facility. We also investigated the response of isoprene emission to foliar N, P and abscisic acid (ABA) contents in September because the 2-C-methylerythritol-5-phosphate (MEP) pathway of isoprenoid biosynthesis produces ABA. We found that O3 increased isoprene emission in July, which was associated to increased dark respiration, suggesting an activation of metabolism against O3 stress as an initial response. However, O3 decreased isoprene emission in September which was associated to reduced net photosynthesis. In September, isoprene emission was positively correlated with leaf N content and negatively correlated with leaf P content in AA. However, no response of isoprene emission to foliar N and P was found in elevated O3, suggesting that the isoprene responses to foliar N and P depended on the O3 exposure levels. Isoprene emission rate in 1.5 × AA and 2.0 × AA increased with increasing leaf ABA content, indicating accelerated senescence of injured leaves to favor new leaf growth when high O3 and nutritional availability in the soil were combined. Even though foliar N and P usually act as a proxy for isoprene emission rate, the impact of recent abiotic factors such as O3 should be always considered for modeling isoprene emission under climate change.Manganese oxides (MnOx) and Mn2+ usually co-exist in the natural environment, as well as in water treatments for Mn2+ removal. Therefore, it is necessary to investigate the influence of Mn2+ on the stability of MnOx nanoparticles, as it is vital to their fate and reactivity. In this study, we used the time-resolved dynamic light scattering technique to study the influence of Mn2+ on the initial aggregation kinetics of MnOx nanoparticles. The results show that Mn2+ was highly efficient in destabilizing MnOx nanoparticles. The critical coagulation concentration ratio of Mn2+ (0.3 mM) to Na+ (30 mM) was 2-6.64, which is beyond the ratio range indicated by the Schulze-Hardy rule. This is due to the coordination bond formed between Mn2+ and the surface O of MnOx, which could efficiently decrease the negative surface charge of MnOx. As a result, in the co-presence of Mn2+ and Na+, a small amount of Mn2+ (5 μM) could efficiently neutralize the negative charge of MnOx, thereby decreasing the amount of Na+, which mainly destabilized nanoparticles through electric double-layer compression, required to initiate aggregation.