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Wetlands as long-term sources of metals to receiving waters in mining-impacted landscapes
2014
Szkokan-Emilson, E.J. | Watmough, S.A. | Gunn, J.M.
Wetlands are prevalent in the Sudbury, Ontario region and often operate at the interface between terrestrial and aquatic ecosystems, modifying water chemistry and potentially affecting the recovery of impacted lakes. The deposition of metals and sulphur in Sudbury in 2010–2012 was far below that reported in the 1970's, but still higher than background values. Wetlands in the area have accumulated large quantities of metals, and high concentrations of these metals in streams occurred primarily in response to SO4-related acidification events or associated with high dissolved organic carbon production in early summer. Concentrations of most metals in streams exceeded provincial guidelines and fluxes of some metals from catchments exceeded deposition inputs to lakes by as much as 12 times. The release of metals long after emissions reductions have been achieved must be considered in ecosystem recovery studies, particularly as dry conditions may become more prevalent in boreal regions affected by mining.
显示更多 [+] 显示较少 [-]Long-term source apportionment of ambient fine particulate matter (PM2.5) in the Los Angeles Basin: A focus on emissions reduction from vehicular sources
2014
Hasheminassab, Sina | Daher, Nancy | Ostro, Bart D. | Sioutas, Constantinos
Positive Matrix Factorization (PMF) was utilized to quantify sources of ambient PM2.5 in central Los Angeles (LA) and Rubidoux, using the Speciation Trends Network data, collected between 2002 and 2013. Vehicular emissions (including gasoline and diesel vehicles) were the second major contributor to PM2.5, following secondary aerosols, with about 20% contribution to total mass in both sites. Starting in 2007, several major federal, state, and local regulations on vehicular emissions were implemented. To assess the effect of these regulations, daily-resolved vehicular source contributions from 2002 to 2006 were pooled together and compared to the combination of 2008 to 2012 datasets. Compared to the 2002–2006 dataset, the median values of vehicular emissions in 2008–2012 statistically significantly decreased by 24 and 21% in LA and Rubidoux, respectively. These reductions were noted despite an overall increase or similarity in the median values of the daily flow of vehicles after 2007, at the sites.
显示更多 [+] 显示较少 [-]Metal and nutrient dynamics in decomposing tree litter on a metal contaminated site
2014
Van Nevel, Lotte | Mertens, Jan | Demey, Andreas | De Schrijver, An | De Neve, S. (Stefaan) | Tack, Filip M.G. | Verheyen, Kris
In a forest on sandy, metal polluted soil, we examined effects of six tree species on litter decomposition rates and accompanied changes in metal (Cd, Zn) and nutrient (base cations, N, C) amounts. Decomposition dynamics were studied by means of a litterbag experiment lasting for 30 months. The decomposition peak occurred within the first year for all tree species, except for aspen. During litter decomposition, high metal litter types released part of their accumulated metals, whereas low metal litter types were characterized by a metal enrichment. Base cations, N and C were released from all litter types. Metal release from contaminated litter might involve risks for metal dispersion towards the soil. On the other hand, metal enrichment of uncontaminated litter may be ecologically relevant as it can be easily transported or serve as food source.
显示更多 [+] 显示较少 [-]Effects of nitrogen additions on biomass, stoichiometry and nutrient pools of moss Rhytidium rugosum in a boreal forest in Northeast China
2014
Du, Enzai | Liu, Xiuyuan | Fang, Jingyun
Global nitrogen (N) deposition has been enhanced with anthropogenic N emissions, and its impacts on mosses are receiving more and more attention. This study investigates how N deposition influence the biomass and stoichiometry of moss Rhytidium rugosum, using a 3-year N enrichment experiment with 0, 2, 5 and 10 g N m−2 yr−1 in a boreal forest in Northeast China. Low N additions caused an N redundancy and moderate to high N additions resulted in a biomass loss. N additions reduced biomass ratios of green to brown tissues and increased N and phosphorus (P) contents, suggesting changes in photosynthetic capacity and litter decomposition. Biomass N pools showed a unimodal response to the N additions, and P pools decreased under moderate and high N additions. Our findings indicate significant stoichiometric and biomass changes caused by N deposition may lead to a substantial carbon and nutrient loss in boreal moss carpets.
显示更多 [+] 显示较少 [-]Occurrence and removal of drugs of abuse in Wastewater Treatment Plants of Valencia (Spain)
2014
Andrés-Costa, María Jesús | Rubio-López, Nuria | Morales Suárez-Varela, María | Picó, Yolanda
The occurrence of 8 drugs of abuse and metabolites in the influent and effluent of the 3 Wastewater Treatment Plants (WWTP) that treat wastewater from Valencia was studied in 2011, 2012 and 2013. Target drugs except 6-monoacetylmorphine (6-ACMOR) were detected in 100% of the influents. The WWTPs eliminate cocaine (COC), amphetamine (AMP), methamphetamine (MAMP) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). Benzoylecgonine (BECG) was also efficiently eliminated (93–98%), whereas 3,4-methylenedioxymethamphetamine (MDMA) presented removal rates of 32–57% and ketamine (KET) was not eliminated. The most consumed illicit drugs, according to the estimated concentrations of each compound in the studied WWTPs, were cannabis and COC followed by KET, AMP, MAMP, MDMA and heroin. Environmental risk assessment was evaluated by calculating Risk Quotient (RQ). MDMA and KET could pose a medium risk and low risk, respectively, to the aquatic organisms. Although short-term environmental risk is not worrisome, long-term effects cannot be known exactly.
显示更多 [+] 显示较少 [-]The effects of dust–haze on mortality are modified by seasons and individual characteristics in Guangzhou, China
2014
Liu, Tao | Zhang, Yong Hui | Xu, Yan Jun | Lin, Hua Liang | Xu, Xiao Jun | Luo, Yuan | Xiao, JianPeng | Zeng, Wei Lin | Zhang, Wan Fang | Chu, Cordia | Keogh, Kandice | Rutherford, Shannon | Qian, Zhengmin | Du, Yao Dong | Hu, Mengjue | Ma, Wen Jun
This study aimed to investigate the effects of dust–haze on mortality and to estimate the seasonal and individual-specific modification effects in Guangzhou, China. Mortality, air pollution and meteorological data were collected for 2006–2011. A dust–haze day was defined as daily visibility <10 km with relative humidity <90%. This definition was further divided into light (8–10 km), medium (5–8 km) and heavy dust–haze (<5 km). A distributed lag linear model (DLM) was employed. Light, medium and heavy dust–haze days were associated with increased mortality of 3.4%, 6.8% and 10.4% respectively, at a lag of 0–6 days. This effect was more pronounced during the cold season, for cardiovascular mortality (CVD), respiratory mortality (RESP), in males and people ≥60years. These effects became insignificant after adjustment for PM10. We concluded that dust–haze significantly increased mortality risk in Guangzhou, China, and this effect appears to be dominated by particulate mass and modified by season and individual-specific factors.
显示更多 [+] 显示较少 [-]Distribution of atmospheric particulate matter (PM) in rural field, rural village and urban areas of northern China
2014
Li, Wei | Wang, Chen | Wang, Hongqijie | Chen, Jiwei | Yuan, Chenyi | Li, Tongchao | Wang, Wentao | Shen, Huizhong | Huang, Ye | Wang, Rong | Wang, Bin | Zhang, Yanyan | Chen, Han | Chen, Yuanchen | Tang, Jianhui | Wang, Xilong | Liu, Junfeng | Coveney, Raymond M. | Tao, Shu
Atmospheric PM10 were measured for 12 months at 18 sites along a 2500 km profile across northern China. Annual mean PM10 concentrations in urban, rural village, and rural field sites were 180 ± 171, 182 ± 154, and 128 ± 89 μg/m3, respectively. The similarities in PM10 concentrations between urban and rural village sites suggest that strong localized emissions and severe contamination in rural residential areas are derived from solid fuels combustion in households. High PM10 concentrations in Wuwei and Taiyuan were caused by either sandstorms or industrial activities. Relatively low PM10 concentrations were observed in coastal areas of Dalian and Yantai. Particulate air pollution was much higher in winter and spring than in summer and fall. Multiple regression analysis indicates that 35% of the total variance can be attributed to sandstorms, precipitation and residential energy consumption. Over 40% of the measurements in both urban and rural village areas exceeded the national ambient air quality standard.
显示更多 [+] 显示较少 [-]Evaluation of effects of long term exposure on lethal toxicity with mammals
2014
Verma, Vibha | Yu, Qiming J. | Connell, D. W.
The relationship between exposure time (LT50) and lethal exposure concentration (LC50) has been evaluated over relatively long exposure times using a novel parameter, Normal Life Expectancy (NLT), as a long term toxicity point. The model equation, ln(LT50) = aLC50ν + b, where a, b and ν are constants, was evaluated by plotting lnLT50 against LC50 using available toxicity data based on inhalation exposure from 7 species of mammals. With each specific toxicant a single consistent relationship was observed for all mammals with ν always <1. Use of NLT as a long term toxicity point provided a valuable limiting point for long exposure times. With organic compounds, the Kow can be used to calculate the model constants a and v where these are unknown. The model can be used to characterise toxicity to specific mammals and then be extended to estimate toxicity at any exposure time with other mammals.
显示更多 [+] 显示较少 [-]Identification of lead sources in residential environments: Sydney Australia
2014
Laidlaw, M.A.S. | Zahran, S. | Pingitore, N. | Clague, J. | Devlin, G. | Taylor, M.P.
Interior and exterior dust, soil and paint were analysed at five brick urban Sydney homes over 15 months to evaluate temporal variations and discriminate sources of lead (Pb) exposure. Exterior dust gauge Pb loading rates (μg/m2/28 days), interior vacuum dust Pb concentrations (mg/kg) and interior petri-dish Pb loading rates (μg/m2/28 days), were correlated positively with soil Pb concentrations. Exterior dust gauge Pb loading rates and interior vacuum dust Pb concentrations peaked in the summer. Lead isotope and Pb speciation (XAS) were analysed in soil and vacuum dust samples from three of the five houses that had elevated Pb concentrations. Results show that the source of interior dust lead was primarily from soil in two of the three houses and from soil and Pb paint in the third home. IEUBK child blood Pb modelling predicts that children's blood Pb levels could exceed 5 μg/dL in two of the five houses.
显示更多 [+] 显示较少 [-]Changes in the adsorption of bisphenol A, 17 α-ethinyl estradiol, and phenanthrene on marine sediment in Hong Kong in relation to the simulated sediment organic matter decomposition
2014
Fei, Ying-heng | Xing, Baoshan | Li, Xiao-yan
Marine sediment with an input of particulate organic matter was incubated to simulate the early aging process. On the sediment after various incubation periods, adsorption and desorption tests were conducted for three selected organic micropollutants: bisphenol A (BPA), 17α-ethinyl estradiol (EE2), and phenanthrene (Phe). The results showed significant sediment organic matter (SOM) decomposition during the incubation, and the SOM decay and transformation had a profound impact on the adsorption of organic compounds by the sediment. An increasing-delay-increasing pattern of change was observed for the SOM normalized partition coefficients of EE2 and Phe. This change was accordant to the transformation of SOM from labile organics into active biomass and its microbial products, and finally into more condensed and humic-like substances. Comparison between the 3 model micropollutants indicates that the chemical adsorption behaviors were mostly affected by their hydrophobic properties.
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