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النتائج 231 - 240 من 1,966
Source contributions to carbonaceous species in PM2.5 and their uncertainty analysis at typical urban, peri-urban and background sites in southeast China النص الكامل
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.
اظهر المزيد [+] اقل [-]Distributions, sources and pollution status of 17 trace metal/metalloids in the street dust of a heavily industrialized city of central China النص الكامل
2013
Li, Zhonggen | Feng, Xinbin | Li, Guanghui | Bi, Xiangyang | Zhu, Jianming | Qin, Haibo | Dai, Zhihui | Liu, Jinling | Li, Qiuhua | Sun, Guangyi
A series of representative street dust samples were collected from a heavily industrialized city, Zhuzhou, in central China, with the aim to investigate the spatial distribution and pollution status of 17 trace metal/metalloid elements. Concentrations of twelve elements (Pb, Zn, Cu, Cd, Hg, As, Sb, In, Bi, Tl, Ag and Ga) were distinctly amplified by atmospheric deposition resulting from a large scale Pb/Zn smelter located in the northwest fringe of the city, and followed a declining trend towards the city center. Three metals (W, Mo and Co) were enriched in samples very close to a hard alloy manufacturing plant, while Ni and Cr appeared to derive predominantly from natural sources. Other industries and traffic had neglectable effects on the accumulation of observed elements. Cd, In, Zn, Ag and Pb were the five metal/metalloids with highest pollution levels and the northwestern part of city is especially affected by heavy metal pollution.
اظهر المزيد [+] اقل [-]Diasteroisomer and enantiomer-specific profiles of hexabromocyclododecane and tetrabromobisphenol A in an aquatic environment in a highly industrialized area, South China: Vertical profile, phase partition, and bioaccumulation النص الكامل
2013
He, Ming-Jing | Luo, Xiao-Jun | Yu, Le-Huan | Wu, Jiang-Ping | Chen, She-Jun | Mai, Bi-Xian
Tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs) were determined in water, sediments, sediment cores, and three fish species from a river running through a highly industrialized area in South China. TBBPA concentrations exceeded those of HBCDs in the sediment and the dissolved phase of water and its levels in fish were at the high end of worldwide figures. 26% of HBCDs and 99% of TBBPA were found in dissolved phase of water. Plecostomus occupying high trophic level exhibited higher HBCD levels and higher abundance of α-HBCD than mud carp and nile tilapia which occupy low trophic level. An enrichment of (+)-α-HBCD in three fish species but (−)-α-HBCD in sediment was observed. As for γ-HBCD, most of sediment exhibited racemic while a species-dependence in fish sample was found. No clear trend was found for vertical distribution of enantiomeric profile for γ-HBCD, suggesting that the enantioselectivity of degradation of γ-HBCD is limited.
اظهر المزيد [+] اقل [-]Enhancing the biodegradation of oil in sandy sediments with choline: A naturally methylated nitrogen compound النص الكامل
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.
اظهر المزيد [+] اقل [-]Placental IGF-1 and IGFBP-3 expression correlate with umbilical cord blood PAH and PBDE levels from prenatal exposure to electronic waste النص الكامل
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.
اظهر المزيد [+] اقل [-]Measurement of humic-like substances in aerosols: A review النص الكامل
2013
Zheng, Guangjie | He, Kebin | Duan, Fengkui | Cheng, Yuan | Ma, Yongliang
Aerosol-phase humic-like substances (HULIS) have received increasingly attention due to their universal ambient presence, active participation in atmospheric chemistry and important environmental and health effects. In last decade, intensive field works have promoted development of quantification and analysis method, unearthed spatio-temporal variation, and proved evidence for source identification of HULIS. These important developments were summarized in this review to provide a global perspective of HULIS. The diverse operational HULIS definitions were gradually focused onto several versions. Although found globally in Europe, Asia, Australasia and North America, HULIS are far more typical in continental and near-ground aerosols. HULIS concentrations varied from <1 μg/m3 to >13 μg/m3, with their carbon fraction making up 9%–72% of water soluble organic carbon. Dominant HULIS source was suggested as secondary processes and biomass burning, with the detailed formation pathways suggested and verified in laboratory works.
اظهر المزيد [+] اقل [-]Phytotoxicity and oxidative stress effect of 1-octyl-3-methylimidazolium chloride ionic liquid on rice seedlings النص الكامل
2013
Liu, Huijun | Zhang, Shuxian | Hu, Xiaona | Chen, Caidong
The effects of the ionic liquid 1-octyl-3-methylimidazolium chloride ([OMIM]Cl) was studied in hydroponically grown rice seedlings. Observed effects included increased root length and weight at concentrations of 0.1 mg/L [OMIM]Cl, however, as concentrations increased a reversed response was observed where roots and stems grew shorter and the weight decreased. The inhibitory concentration 50 (IC50,5d) values for root length and stem length were 0.59 mg/L and 0.70 mg/L, respectively. The Hill reaction activity and root system activity in [OMIM]Cl-treated rice seedlings were observed to be lower than the controls, however, root membrane permeability increased. The antioxidant enzyme activity in roots decreased, while in leaves there was an initial stimulation followed by a decrease. Malondialdehyde (MDA) content was found to be greater in seedlings subjected to [OMIM]Cl treatment. The cellular structures, such as chloroplasts, mitochondria and rough endoplasmic reticulum in rice root and leaf cells were affected at concentrations of 0.6 mg/L [OMIM]Cl.
اظهر المزيد [+] اقل [-]Quantitative analysis on the urban flood mitigation effect by the extensive green roof system النص الكامل
2013
Lee, J.Y. | Moon, H.J. | Kim, T.I. | Kim, H.W. | Han, M.Y.
Extensive green-roof systems are expected to have a synergetic effect in mitigating urban runoff, decreasing temperature and supplying water to a building. Mitigation of runoff through rainwater retention requires the effective design of a green-roof catchment. This study identified how to improve building runoff mitigation through quantitative analysis of an extensive green-roof system. Quantitative analysis of green-roof runoff characteristics indicated that the extensive green roof has a high water-retaining capacity response to rainfall of less than 20 mm/h. As the rainfall intensity increased, the water-retaining capacity decreased. The catchment efficiency of an extensive green roof ranged from 0.44 to 0.52, indicating reduced runoff comparing with efficiency of 0.9 for a concrete roof. Therefore, extensive green roofs are an effective storm water best-management practice and the proposed parameters can be applied to an algorithm for rainwater-harvesting tank design.
اظهر المزيد [+] اقل [-]Estimation of the algal-available phosphorus pool in sediments of a large, shallow eutrophic lake (Taihu, China) using profiled SMT fractional analysis النص الكامل
2013
Zhu, Mengyuan | Zhu, Guangwei | Li, Wei | Zhang, Yunlin | Zhao, Linlin | Gu, Zhao
Because large, shallow lakes are heavily influenced by wind–wave disturbance, it is difficult to estimate internal phosphorus load using traditional methods. To estimate the potential contribution of phosphorus from sediment to overlying water in eutrophic Lake Taihu, phosphorus fractions of surface and deep layer sediments were quantified and analyzed for algal bloom potential using a Standard Measurements and Testing (SMT) sequential extraction method and incubation experiments. Phosphorus bound to Fe, Al and Mn oxides and hydroxides (Fe–P) and organic phosphorus (OP) were to be found bioactive. The difference in Fe–P and OP contents between surface and deep layers equates to the sediment pool of potentially algal-available phosphorus. This pool was estimated at 5168 tons for the entire lake and was closely related to pollution input and algal blooms. Profiled SMT fractionation analysis is thus a potentially useful tool for estimating internal phosphorus loading in large, shallow lakes.
اظهر المزيد [+] اقل [-]Increased frequency and severity of developmental deformities in rough-skinned newt (Taricha granulosa) embryos exposed to road deicing salts (NaCl & MgCl2) النص الكامل
2013
Hopkins, Gareth R. | French, Susannah S. | Brodie, Edmund D.
Road-side aquatic ecosystems in North America are annually polluted with millions of tons of road deicing salts, which threaten the survival of amphibians which live and breed in these habitats. While much is known of the effects of NaCl, little is known of the second most-commonly used deicer, MgCl2, which is now used exclusively in parts of the continent. Here we report that environmentally relevant concentrations of both NaCl and MgCl2 cause increased incidence of developmental deformities in rough-skinned newt hatchlings that developed embryonically in these salts. In addition, we provide some of the first quantification of severity of different deformities, and reveal that increased salt concentrations increase both deformity frequency and severity. Our work contributes to the growing body of literature that suggests salamanders and newts are particularly vulnerable to salt, and that the emerging pollutant, MgCl2 is comparable in its effects to the more traditionally-used NaCl.
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