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Resultados 201-210 de 1,953
Enhancing the biodegradation of oil in sandy sediments with choline: A naturally methylated nitrogen compound
2013
Mortazavi, Behzad | Horel, Agota | Anders, Jennifer S. | Mirjafari, Arsalan | Beazley, Melanie J. | Sobecky, Patricia A.
We investigated how additions of choline, a naturally occurring methylated nitrogen-containing compound, accelerated hydrocarbon degradation in sandy sediments contaminated with moderately weathered crude oil (4000 mg kg−1 sediment). Addition of lauroylcholine chloride (LCC) and tricholine citrate (TCC) to oil contaminated sediments resulted in 1.6 times higher hydrocarbon degradation rates compared to treatments without added choline derivatives. However, the degradation rate constant for the oil contaminated sediments amended with LCC was similar to that in contaminated sediments amended with inorganic nitrogen, phosphorus, and glucose. Additions of LLC and TCC to sediments containing extensively weathered oil also resulted in enhanced mineralization rates. Cultivation-free 16S rRNA analysis revealed the presence of an extant microbial community with clones closely related to known hydrocarbon degraders from the Gammaproteobacteria, Alphaproteobacteria, and Firmicutes phyla. The results demonstrate that the addition of minimal amounts of organic compounds to oil contaminated sediments enhances the degradation of hydrocarbons.
Mostrar más [+] Menos [-]Placental IGF-1 and IGFBP-3 expression correlate with umbilical cord blood PAH and PBDE levels from prenatal exposure to electronic waste
2013
Xu, Xijin | Yekeen, Taofeek Akangbe | Xiao, Qiongna | Wang, Yuangping | Lu, Fangfang | Huo, Xia
Electronic waste recycling produces Polycyclic Aromatic Hydrocarbons (PAHs) and Polybrominated Diphenyl Ethers (PBDEs) which may affect fetal growth and development by altering the insulin-like-growth factor (IGF) system. Questionnaires were administered to pregnant women (Guiyu, an e-waste site, n = 101; control, n = 53), and umbilical cord blood (UCB) and placentas were collected upon delivery. PBDEs and PAHs in UCB and placental IGF-1 and IGFBP-3 mRNA levels were analyzed using GC–MS and real-time PCR, respectively. Infant birth length and Apgar scores were lower in Guiyu. All PAHs (except Fl, Chr, IP, BbF and BP), total 16-PAHs, total/individual PBDEs, placental IGF-1 (median 0.23 vs 0.19; P < 0.05) and IGFBP-3 (median 1.91 vs 0.68; P < 0.001) levels were significantly higher in Guiyu. Spearman correlation showed that BDE-154, BDE-209 and ∑5ring-PAHs positively correlate with IGF-1 while PBDEs, 4 rings and total PAHs correlate with IGFBP-3 expression. Increased placental IGF-1 level might indirectly affect fetal growth and development.
Mostrar más [+] Menos [-]Toxicities of oils, dispersants and dispersed oils to algae and aquatic plants: Review and database value to resource sustainability
2013
Lewis, Michael | Pryor, Rachel
Phytotoxicity results are reviewed for oils, dispersants and dispersed oils. The phytotoxicity database consists largely of results from a patchwork of reactive research conducted after oil spills to marine waters. Toxicity information is available for at least 41 crude oils and 56 dispersants. As many as 107 response parameters have been monitored for 85 species of unicellular and multicellular algae, 28 wetland plants, 13 mangroves and 9 seagrasses. Effect concentrations have varied by as much as six orders of magnitude due to experimental diversity. This diversity restricts phytotoxicity predictions and identification of sensitive species, life stages and response parameters. As a result, evidence-based risk assessments for most aquatic plants and petrochemicals and dispersants are not supported by the current toxicity database. A proactive and experimentally-consistent approach is recommended to provide threshold toxic effect concentrations for sensitive life stages of aquatic plants inhabiting diverse ecosystems.
Mostrar más [+] Menos [-]Distribution and fate of perfluoroalkyl substances in municipal wastewater treatment plants in economically developed areas of China
2013
Zhang, Wei | Zhang, Yating | Taniyasu, Sachi | Yeung, Leo W.Y. | Lam, Paul K.S. | Wang, Jianshe | Li, Xinhai | Yamashita, Nobuyoshi | Dai, Jiayin
Wastewater treatment plants (WWTPs) are a significant source for poly-/perfluoroalkyl substances (PFASs) entering the environment. The presence of PFASs in twenty-eight municipal WWTPs from eleven cites in economically developed areas of China were screened. Overall, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were dominant in wastewater and sludge, and were not effectively removed during wastewater treatment. Elevated influent concentration ratios of perfluorobutanoic acid (PFBA) to PFOA and perfluorobutane sulfonate (PFBS) to PFOS in some WWTPs suggested that short chains substitution were adopted in these cities. Cluster analysis showed treatment processes had important impacts on PFASs profiles in effluent and sludge. Average concentration of total PFCAs in influent from each city and its gross domestic product (GDP) had significant positive correlation. This study provides a snapshot of both domestic and industrial discharges of PFAS to WWTPs as well as PFAS discharge from WWTPs to the aquatic environment in China.
Mostrar más [+] Menos [-]Assessing the combined risks of PAHs and metals in urban soils by urbanization indicators
2013
Peng, Chi | Ouyang, Z. (Zhiyun) | Wang, Meie | Chen, Weiping | Li, Xiaoma | Crittenden, John C.
We quantitatively describe the impacts of urbanization on the accumulation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in urban soils as well as their health risks to residents. Residential building age, population density, road density, and distance from urban center were used as urbanization level indicators. Significant correlations were found between those urbanization indicators and the amounts of PAHs, Cu, Cd, Pb, Zn and As in residential soils. The exposure time of soils to urban air was the primary factor affecting soil pollution, followed by local road density and population density. Factor analysis suggested that 59.0% of the elevated pollutant concentrations were caused by citywide uniform deposition, and 15.3% were resulted from short-range deposition and/or non-combustion processes. The combined health risks posed by soil PAHs and HMs were aggravated with time and can be expressed as functions of residence age, road density, and other urbanization indicators.
Mostrar más [+] Menos [-]Associations of prenatal exposure to phenols with birth outcomes
2013
Tang, Rong | Chen, Min-jian | Ding, Guo-dong | Chen, Xiao-jiao | Han, Xiu-mei | Zhou, Kun | Chen, Li-Mei | Xia, Yan-kai | Tian, Ying | Wang, Xin-ru
Many phenols are known to mimic or antagonize hormonal activities and may adversely affect fetal growth. A study of 567 pregnant women was conducted to investigate the relationship between prenatal phenol exposure and birth outcomes, including birth weight, length, and gestational age. We measured the concentrations of bisphenol A, benzophenone-3, 4-n-octylphenol and 4-n-nonylphenol in maternal urine and examine their association with birth outcomes. Categories of urinary benzophenone-3 concentration were associated with decreased gestational age in all infants (p for trend = 0.03). Between middle and low exposure groups, we also found bisphenol A was negatively associated with gestational duration (βadjusted = −0.48 week; 95% confidence interval: −0.91, −0.05). After stratification by gender, we found the consistent results in infant boys with those in all infants, but we did not observe significant association for girls. In conclusion, we found prenatal phenol exposure was sex-specifically related to birth outcomes.
Mostrar más [+] Menos [-]Are plants useful as accumulation indicators of metal bioavailability?
2013
Remon, E. | Bouchardon, J.-L. | Le Guédard, M. | Bessoule, J.-J. | Conord, C. | Faure, O.
The use of accumulation bioindicator to assess metal bioavailability has mainly concerned individual species. This work addresses this issue at the plant community level. Metal content within different species from plant communities found at three contaminated and one uncontaminated site was compared. Results showed that for two contaminated sites, leaf metals concentrations were comparable to those in plants from control site, i.e. approx (mg/kg) 0.1 Cd, 0.2 Cr, 9.2 Cu, 1.8 Ni, 0.5 Pb and 42 Zn. Only plants from the third site showed higher metal contents, ranging from 1.5- to 8-fold those of the control community. This contrasted with ammonium acetate–EDTA extractions, which indicated a very high “availability” of metals at the three sites, as compared to the control site. Thus, metal content in plant communities provided accurate information on actual transfer toward the ensemble of vegetation, which could be used to establish site-specific “fingerprints” of metal bioavailability.
Mostrar más [+] Menos [-]Source contributions to carbonaceous species in PM2.5 and their uncertainty analysis at typical urban, peri-urban and background sites in southeast China
2013
Niu, Zhenchuan | Wang, Sen | Chen, Jinsheng | Zhang, Fuwang | Chen, Xiaoqiu | He, Chi | Lin, Lifeng | Yin, Liqian | Xu, Lingling
Determination of 14C and levoglucosan can provide insights into the quantification of source contributions to carbonaceous aerosols, yet there is still uncertainty on the partitioning of organic carbon (OC) into biomass burning OC (OCbb) and biogenic emission OC (OCbio). Carbonaceous species, levoglucosan and 14C in PM2.5 were measured at three types of site in southeast China combined with Latin hypercube sampling, with the objectives to study source contributions to total carbon (TC) and their uncertainties, and to evaluate the influence of levoglucosan/OCbb ratios on OCbb and OCbio partitioning. It was found reliably that fossil fuel combustion is the main contributor (62.90–72.23%) to TC at urban and peri-urban sites. Biogenic emissions have important contribution (winter, 52.98%; summer, 45.71%) to TC at background site. With the increase in levoglucosan/OCbb ratios, the contribution of OCbio is increased while OCbb is decreased in a pattern of approximate natural logarithm at a given range.
Mostrar más [+] Menos [-]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
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.
Mostrar más [+] Menos [-]Sorption, dissolution and pH determine the long-term equilibration and toxicity of coated and uncoated ZnO nanoparticles in soil
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.
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