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Результаты 121-130 из 1,956
Supercritical fluid extraction of persistent organic pollutants from natural and artificial soils and comparison with bioaccumulation in earthworms Полный текст
2013
Bielská, Lucie | Šmídová, Klára | Hofman, Jakub
Selective supercritical fluid extraction (SSFE) was used as a measurement of compound chemical accessibility and as a predictor of compound bioavailability from three natural soils and artificial analogues prepared to have comparable total organic carbon content. Soils spiked with phenanthrene, pyrene, PCB 153, lindane, and p,p′-DDT were aged for 0, 14, 28, or 56 days and then selectively extracted by supercritical fluid extraction. Compounds exhibited decreasing extractability with increasing pollutant–soil contact time and increasing total organic carbon content in tested soils. However, the different extractability of compounds from artificial and natural pairs having comparable TOC indicates the limitations of using TOC as an extrapolation basis between various soils. The comparison of extractability with bioaccumulation by earthworms (Eisenia fetida) previously published by Vlčková and Hofman (2012) showed that only for PAHs it was possible to predict their bioaccumulation by means of selective SFE.
Показать больше [+] Меньше [-]Enhancement of water solubility and mobility of phenanthrene by natural soil nanoparticles Полный текст
2013
Li, Wenyan | Zhu, Xinyu | He, Yan | Xing, Baoshan | Xu, Jianming | Brookes, Philip C.
Nanoparticles (NPs) in soils may participate in essential ecological services, since they have special characteristics arising from their nanoscale sizes and large surface areas. We did aqueous solubility enhancement experiments to derive the partition coefficients of phenanthrene between water and six natural soil NPs. The coefficients were approximately exponentially reduced with increasing concentrations of NPs, low concentrations of NPs (50 mg L−1) had significant high adsorption capacities for phenanthrene. Further experiments based on dynamic light scattering technique and column tests were performed to examine the aggregation and mobility of soil NPs and how they influence phenanthrene mobility in porous media. NPs have high and reversible adsorption on surfaces of porous media with aggregation taking place during their transport and they largely control the mobility of phenanthrene in sand columns.
Показать больше [+] Меньше [-]Lead bioaccessibility in topsoils from lead mineralisation and urban domains, UK Полный текст
2013
Appleton, J.D. | Cave, M.R. | Palumbo-Roe, B. | Wragg, J.
Predictive linear regression (LR) modelling indicates that total Pb is the only highly significant independent variable for estimating Pb bioaccessibility in “mineralisation domains” located in limestone (high pH) and partly peat covered (low pH) shale-sandstone terrains in England. Manganese is a significant minor predictor in the limestone terrain, whilst organic matter and sulphur explain 0.5% and 2% of the variance of bioaccessible Pb in the peat-shale-sandstone terrain, compared with 93% explained by total Pb. Bootstrap resampling shows that LR confidence limits overlap for the two mineralised terrains but the limestone terrain has a significantly lower bioaccessible Pb to total Pb slope than the urban domain. A comparison of the absolute values of stomach and combined stomach-intestine bioaccessibility provides some insight into the geochemical controls on bioaccessibility in the contrasting soil types.
Показать больше [+] Меньше [-]Short- and long-term temporal changes in soil concentrations of selected endocrine disrupting compounds (EDCs) following single or multiple applications of sewage sludge to pastures Полный текст
2013
Rhind, S.M. | Kyle, C.E. | Ruffie, H. | Calmettes, E. | Osprey, M. | Zhang, Z.L. | Hamilton, D. | McKenzie, C.
Temporal changes in soil burdens of selected endocrine disrupting compounds were determined following application to pasture of either sewage sludge or inorganic fertilizer. Soil polycyclic aromatic hydrocarbon and polychlorinated biphenyl concentrations were not altered. Changes in concentrations of diethylhexyl phthalate (DEHP) and PBDEs 47 and 99 differed with season but concentrations remained elevated for more than three weeks after application, when grazing animals are normally excluded from pasture. It is concluded that single applications of sewage sludge can increase soil concentrations of some, but not all classes of EDCs, possibly to concentrations sufficient to exert biological effects when different chemicals act in combination, but patterns of change depend on season and soil temperature. Analysis of soil from pasture subjected to repeated sludge applications, over 13 years, provided preliminary evidence of greater increases in soil burdens of all of the EDC groups measured, including all of the PBDE congeners measured.
Показать больше [+] Меньше [-]Characterization and influence of biochars on nitrous oxide emission from agricultural soil Полный текст
2013
Wang, Zhenyu | Zheng, Hao | Luo, Ye | Deng, Xia | Herbert, Stephen | Xing, Baoshan
Extensive use of biochar to mitigate N2O emission is limited by the lack of understanding on the exact mechanisms altering N2O emissions from biochar-amended soils. Biochars produced from giant reed were characterized and used to investigate their influence on N2O emission. Responses of N2O emission varied with pyrolysis temperature, and the reduction order of N2O emission by biochar (BC) was: BC200 ≈ BC600 > BC500 ≈ BC300 ≈ BC350 > BC400. The reduced emission was attributed to enhanced N immobilization and decreased denitrification in the biochar-amended soils. The remaining polycyclic aromatic hydrocarbons (PAHs) in low-temperature biochars (300–400 °C) played a major role in reducing N2O emission, but not for high-temperature biochars (500–600 °C). Removal of phenolic compounds from low-temperature (200–400 °C) biochars resulted in a surprising reduction of N2O emission, but the mechanism is still unknown. Overall, adding giant reed biochars could reduce N2O evolution from agricultural soil, thus possibly mitigating global warming.
Показать больше [+] Меньше [-]Environmental lead exposure risks associated with children's outdoor playgrounds Полный текст
2013
Taylor, Mark Patrick | Camenzuli, Danielle | Kristensen, Louise Jane | Forbes, Miriam | Zahran, Sammy
This study examines exposure risks associated with lead smelter emissions at children's public playgrounds in Port Pirie, South Australia. Lead and other metal values were measured in air, soil, surface dust and on pre- and post-play hand wipes. Playgrounds closest to the smelter were significantly more lead contaminated compared to those further away (t(27.545) = 3.76; p = .001). Port Pirie post-play hand wipes contained significantly higher lead loadings (maximum hand lead value of 49,432 μg/m2) than pre-play hand wipes (t(27) = 3.57, p = .001). A 1% increase in air lead (μg/m3) was related to a 0.713% increase in lead dust on play surfaces (95% CI, 0.253–1.174), and a 0.612% increase in post-play wipe lead (95% CI, 0.257–0.970). Contaminated dust from smelter emissions is determined as the source and cause of childhood lead poisoning at a rate of approximately one child every third day.
Показать больше [+] Меньше [-]Sorption, dissolution and pH determine the long-term equilibration and toxicity of coated and uncoated ZnO nanoparticles in soil Полный текст
2013
Waalewijn-Kool, Pauline L. | Diez Ortiz, Maria | Straalen, N. M. van | van Gestel, Cornelis A.M.
To assess the effect of long-term dissolution on bioavailability and toxicity, triethoxyoctylsilane coated and uncoated zinc oxide nanoparticles (ZnO-NP), non-nano ZnO and ZnCl2 were equilibrated in natural soil for up to twelve months. Zn concentrations in pore water increased with time for all ZnO forms but peaked at intermediate concentrations of ZnO-NP and non-nano ZnO, while for coated ZnO-NP such a clear peak only was seen after 12 months. Dose-related increases in soil pH may explain decreased soluble Zn levels due to fixation of Zn released from ZnO at higher soil concentrations. At T = 0 uncoated ZnO-NP and non-nano ZnO were equally toxic to the springtail Folsomia candida, but not as toxic as coated ZnO-NP, and ZnCl2 being most toxic. After three months equilibration toxicity to F. candida was already reduced for all Zn forms, except for coated ZnO-NP which showed reduced toxicity only after 12 months equilibration.
Показать больше [+] Меньше [-]New approach to the ecotoxicological risk assessment of artificial outdoor sporting grounds Полный текст
2013
Krüger, O. | Kalbe, U. | Richter, E. | Egeler, P. | Römbke, J. | Berger, W.
Artificial surfaces for outdoor sporting grounds may pose environmental and health hazards that are difficult to assess due to their complex chemical composition. Ecotoxicity tests can indicate general hazardous impacts. We conducted growth inhibition (Pseudokirchneriella subcapitata) and acute toxicity tests (Daphnia magna) with leachates obtained from batch tests of granular infill material and column tests of complete sporting ground assemblies. Ethylene propylene diene monomer rubber (EPDM) leachate showed the highest effect on Daphnia magna (EC50 < 0.4% leachate) and the leachate of scrap tires made of styrene butadiene rubber (SBR) had the highest effect on P. subcapitata (EC10 = 4.2% leachate; EC50 = 15.6% leachate). We found no correlations between ecotoxicity potential of leachates and zinc and PAH concentrations. Leachates obtained from column tests revealed lower ecotoxicological potential. Leachates of column tests of complete assemblies may be used for a reliable risk assessment of artificial sporting grounds.
Показать больше [+] Меньше [-]Altered behavior of neonatal northern watersnakes (Nerodia sipedon) exposed to maternally transferred mercury Полный текст
2013
Chin, Stephanie Y. | Willson, John D. | Cristol, Daniel A. | Drewett, David V.V. | Hopkins, William A.
Little is known about effects of maternally transferred contaminants in snakes. The purpose of this study was to evaluate sublethal effects of maternally transferred mercury (Hg) on neonatal northern watersnakes (Nerodia sipedon). We captured 31 gravid females along a historically Hg-contaminated river. Following birth, we measured litter Hg concentrations and assessed locomotor performance, foraging ability (i.e., number of prey eaten, latency to first strike, strike efficiency, and handling time), and learning (i.e., change in foraging measures over time) in their offspring (n = 609). Mercury concentrations in offspring negatively correlated with motivation to feed and strike efficiency. Over time, strike efficiency and latency to strike decreased for all snakes in the study. However, offspring from contaminated areas maintained consistently lower efficiencies than reference individuals. This study is the first to examine sublethal behavioral effects of maternally transferred contaminants in snakes and suggests that maternally transferred Hg negatively affects offspring behavior.
Показать больше [+] Меньше [-]Cumulative impacts of human activities on urban garden soils: Origin and accumulation of metals Полный текст
2013
Szolnoki, Zs | Farsang, A. | Puskás, I.
The concentration of heavy metals and soil properties in fifty urban garden soils of Szeged (SE Hungary) were determined to evaluate the cumulative impacts of urbanization and cultivation on these soils. Using two enrichment factors (EFs) (based on reference horizon; Ti as reference element) and multivariate statistical analysis (PCA), the origin of the studied elements was defined.According to statistical coincidence of EFs confirmed by t-test, anthropogenic enrichment of Cu (EF = 4), Zn (EF = 2.7) and Pb (EF = 2.5) was significant in topsoils. Moreover, PCA also revealed the geogenic origin of Ni, Co, Cr and As and differentiated two groups of the anthropogenic metals [Pb, Zn] [Cu]. Spatial distribution of the metals visualized by GIS reflected the traffic origin of Pb; while based on ANOVA, the anthropogenic source of Cu is relevant (mainly pesticides) and there is a statistically significant difference in its concentration depending on land use.
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