خيارات البحث
النتائج 291 - 300 من 3,207
Effects of atrazine on egg masses of the yellow-spotted salamander (Ambystoma maculatum) and its endosymbiotic alga (Oophila amblystomatis) النص الكامل
2015
Baxter, Leilan | Brain, Richard A. | Hosmer, Alan J. | Nema, Mohini | Müller, Kirsten M. | Solomon, Keith R. | Hanson, Mark L.
Embryonic growth of the yellow-spotted salamander (Ambystoma maculatum) is enhanced by the presence of the green alga Oophila amblystomatis, in the egg capsule. To further assess potential impacts of herbicides on this relationship, A. maculatum egg masses were exposed to atrazine (0–338 μg/L) until hatching (up to 66 days). Exposure to atrazine reduced PSII yield of the symbiotic algae in a concentration-dependent manner, but did not significantly affect visible algal growth or any metrics associated with salamander development. Algal cells were also cultured in the laboratory for toxicity testing. In the 96-h growth inhibition test (0–680 μg/L), ECx values were generally greater than those reported for standard algal test species. Complete recovery of growth rates occurred within 96-h of transferring cells to untreated media. Overall, development of A. maculatum embryos was not affected by exposure to atrazine at concentrations and durations exceeding those found in the environment.
اظهر المزيد [+] اقل [-]Characterization and phthalate esters sorption of organic matter fractions isolated from soils and sediments النص الكامل
2015
Jin, Jie | Sun, Ke | Wang, Ziying | Han, Lanfang | Pan, Zezhen | Wu, Fengchang | Liu, Xitao | Zhao, Ye | Xing, Baoshan
The sorption of two phthalate esters (PAEs) and phenanthrene (PHE) by different natural organic matter fractions (NOMs) was examined. The surface area of the NOMs correlated positively with the starting decomposition temperature (SDT), implying increased number of micropores with the rise of condensation. Sorption of PHE on nonhydrolyzable carbons (NHCs) and other NOMs was respectively dependent on aromatic and aliphatic C contents. Likely physical blocking of the aliphatic moieties and input of black carbon materials led to elevated sorption capacity for PHE of aromatic domains in the NHCs. Sorption of PAEs by NOMs excluding NHCs was jointly regulated by hydrophobic partitioning and H-bonding interactions. The SDT of the NOMs correlated negatively with the Koc when SDT ≥304 °C, likely because the highly condensed domains may impair the availability of amorphous moieties for sorption. This study highlights the influence of domain accessibility of NOMs on sorption of hydrophobic organic contaminants.
اظهر المزيد [+] اقل [-]Damage cost of the Dan River coal ash spill النص الكامل
2015
Dennis Lemly, A.
The recent coal ash spill on the Dan River in North Carolina, USA has caused several negative effects on the environment and the public. In this analysis, I report a monetized value for these effects after the first 6 months following the spill. The combined cost of ecological damage, recreational impacts, effects on human health and consumptive use, and esthetic value losses totals $295,485,000. Because the environmental impact and associated economic costs of riverine coal ash spills can be long-term, on the order of years or even decades, this 6-month assessment should be viewed as a short-term preview. The total cumulative damage cost from the Dan River coal ash spill could go much higher.
اظهر المزيد [+] اقل [-]The role of phytoplankton composition, biomass and cell volume in accumulation and transfer of endocrine disrupting compounds in the Southern Baltic Sea (The Gulf of Gdansk) النص الكامل
2015
Staniszewska, Marta | Nehring, Iga | Zgrundo, Aleksandra
Endocrine disrupting compounds (EDCs) like bisphenol A (BPA), 4-tert-octylphenol (OP) and 4-nonylphenol (NP) are introduced to the trophic webs through among others phytoplankton. This paper describes BPA, OP and NP concentrations in phytoplankton in the Gulf of Gdansk (Southern Baltic Sea) in the years 2011–2012. The assays of BPA, OP and NP in samples were performed using HPLC with fluorescence detection. The concentrations of BPA, the most commonly used of the three compounds, were over ten times higher than OP and NP concentrations. The concentrations of the studied EDCs in phytoplankton from the Gulf of Gdansk depended on anthropogenic factors and on phytoplankton properties (species composition, biomass, volume). An increase in phytoplankton biomass did not always result in an increase of BPA, OP and NP concentrations. However, the load of the studied EDCs accumulated in phytoplankton biomass increase with a rise of biomass. An increase in BPA, OP and NP concentrations was effected by biomass growth and the proportions ofciliates, dinoflagellates, diatoms and green algae. A strong positive correlation between OP and NP concentrations and negative correlation between BPA concentrations and biomass of organisms with cells measuring <1000 μm3 in volume results from the differing properties of these compounds.
اظهر المزيد [+] اقل [-]Environmental contamination in an Australian mining community and potential influences on early childhood health and behavioural outcomes النص الكامل
2015
Dong, Chenyin | Taylor, Mark Patrick | Kristensen, Louise Jane | Zahran, Sammy
Arsenic, cadmium and lead in aerosols, dusts and surface soils from Australia's oldest continuous lead mining town of Broken Hill were compared to standardised national childhood developmental (year 1) and education performance measures (years 3,5,7,9). Contaminants close to mining operations were elevated with maximum lead levels in soil: 8900 mg/kg; dust wipe: 86,061 μg/m2; dust deposition: 2950 μg/m2/day; aerosols: 0.707 μg/m3. The proportion of children from Broken Hill central, the area with the highest environmental contamination, presented with vulnerabilities in two or more developmental areas at 2.6 times the national average. Compared with other school catchments of Broken Hill, children in years 3 and 5 from the most contaminated school catchment returned consistently the lowest educational scores. By contrast, children living and attending schools associated with lower environmental contamination levels recorded higher school scores and lower developmental vulnerabilities. Similar results were identified in Australia's two other major lead mining and smelting cities of Port Pirie and Mount Isa.
اظهر المزيد [+] اقل [-]Application of chemometric analysis and self Organizing Map-Artificial Neural Network as source receptor modeling for metal speciation in river sediment النص الكامل
2015
Pandey, Mayank | Pandey, Ashutosh Kumar | Mishra, Ashutosh | Tripathi, B.D.
Present study deals with the river Ganga water quality and its impact on metal speciation in its sediments. Concentration of physico-chemical parameters was highest in summer season followed by winter and lowest in rainy season. Metal speciation study in river sediments revealed that exchangeable, reducible and oxidizable fractions were dominant in all the studied metals (Cr, Ni, Cu, Zn, Cd, Pb) except Mn and Fe. High pollution load index (1.64–3.89) recommends urgent need of mitigation measures. Self-organizing Map-Artificial Neural Network (SOM-ANN) was applied to the data set for the prediction of major point sources of pollution in the river Ganga.
اظهر المزيد [+] اقل [-]A comparison of Reduced Life Expectancy (RLE) model with Haber's Rule to describe effects of exposure time on toxicity النص الكامل
2015
Verma, Vibha | Yu, Qiming J. | Connell, D. W.
The Reduced Life Expectancy (RLE) Model (LC50 = [ln(NLE) – ln(LT50)]/d) has been proposed as an alternative to Haber's Rule. The model is based on a linear relationship between LC50 (Lethal Exposure Concentration) and lnLT50 (Lethal Exposure Time) and uses NLE (Normal Life Expectancy) as a limiting point as well as a long term data point (where d is a constant). The purposes of this paper were to compare the RLE Model with Haber's Rule with available toxicity data and to evaluate the strengths and weaknesses of each approach. When LT50 is relatively short and LC50 is high, Haber's Rule is consistent with the RLE model. But the difference between the two was evident in the situation when LT50 is relatively long and LC50 is low where the RLE model is a marked departure from Haber's Rule. The RLE Model can be used to appropriately evaluate long term effects of exposure.
اظهر المزيد [+] اقل [-]Induction of c-Jun by air particulate matter (PM10) of Mexico city: Participation of polycyclic aromatic hydrocarbons النص الكامل
2015
Salcido-Neyoy, Martha Estela | Sánchez-Pérez, Yesennia | Osornio-Vargas, Alvaro Román | Gonsebatt, Maria Eugenia | Meléndez-Zajgla, Jorge | Morales-Bárcenas, Rocío | Petrosyan, Pavel | Molina-Servin, Edith Danny | Vega, Elizabeth | Manzano-León, Natalia | García-Cuellar, Claudia M.
The carcinogenic potential of urban particulate matter (PM) has been partly attributed to polycyclic aromatic hydrocarbons (PAHs) content, which activates the aryl hydrocarbon receptor (AhR). Here we report the effect of PM with an aerodynamic size of 10 μm (PM10) on the induction of AhR pathway in A549 cells, evaluating its downstream targets CYP1B1, IL-6, IL-8 and c-Jun. Significant increases in CYP1B1 protein and enzyme activity; IL-6 and IL-8 secretion and c-Jun protein were found in response to PM10. The formation of PAH-DNA adducts was also detected. The involvement of AhR pathway was confirmed with Resveratrol as AhR antagonist, which reversed CYP1B1 and c-Jun induction. Nevertheless, in IL-6 and IL-8 secretion, the Resveratrol was ineffective, suggesting an effect independent of this pathway. Considering the role of c-Jun in oncogenesis, its induction by PM may be contributing to its carcinogenic potential through induction of AhR pathway by PAHs present in PM10.
اظهر المزيد [+] اقل [-]Characterization of the exchange of PBDEs in a subtropical paddy field of China: A significant inputs of PBDEs via air–foliage exchange النص الكامل
2015
Wang, Yan | Wang, Shaorui | Xu, Yue | Luo, Chunling | Li, Jun | Zhang, Gan
Rice and the distinctive cultivation practices employed in rice growth can significantly influence the environmental fate of polybrominated diphenyl ethers (PBDEs) in a paddy field. We studied variations in PBDE concentrations in multiple compartments of a paddy field in the suburban area of Guangzhou, South China, including air, soil, water, and rice tissues. The input/output fluxes of air–surface and air–foliage exchange, atmospheric deposition and water input during different rice growth stages were measured simultaneously. Air–foliage and air–water diffusion exchanges were the key processes controlling inputs and outputs of PBDEs in paddy fields, respectively, whereas atmospheric deposition dominated inputs of higher brominated PBDEs. The high input of PBDEs via air–foliage exchange suggested that vegetation can significantly increase the air-to-field transport of PBDEs in ecosystems. The annual input of PBDEs in all paddy fields in Guangdong Province was estimated to be 22.1 kg.
اظهر المزيد [+] اقل [-]Non-labile silver species in biosolids remain stable throughout 50 years of weathering and ageing النص الكامل
2015
Donner, E. | Scheckel, K. | Sekine, R. | Popelka-Filcoff, R.S. | Bennett, J.W. | Brunetti, G. | Naidu, R. | McGrath, S.P. | Lombi, E.
Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with 110mAg showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 μg/kg (0.002–3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability.
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