خيارات البحث
النتائج 1441 - 1450 من 3,991
Pollution characteristics of atmospheric particulate mercury near a coal-fired power plant on the southeast coast of China
2016
Gao, Jinyu | Wang, Hao | Cai, Wu | Wu, Jingting | He, Yunfeng
PM2.5 and PM10 samples were collected in a rural area from December 2014 to August 2015 near a coal-fired power plant on the southeast coast of China. The total mercury concentrations in PM2.5 ranged from 116.2 to 1070.9 pg/m3 and in PM10 from 173.4 to 1456.8 pg/m3, with averages of 309.5 ± 94.9 and 387.5 ± 133.5 pg/m3, respectively. These were much higher than those found in many foreign cities. The concentrations of mercury in PM2.5 and PM10 varied seasonally, with the highest average concentration in winter. This was probably due to the seasonal variation of meteorological conditions and concentration of particulates. The highest mass-based concentration of mercury in PM2.5 and PM10 was observed in spring. This result might be related to the prevailing sea winds in spring. The spatial variation of particulate mercury conformed to the concentration distribution characteristics of pollutant discharged from coal-fired power plant elevated source at the downwind area. The seasonal variation in the concentrations of the four mercury species (including exchangeable particulate mercury: EXPM, HCl-soluble particulate mercury: HPM, elemental particulate mercury: EPM, and residual particulate mercury: RPM) were all identical to the seasonal variation of total particulate mercury (TPM) in PM2.5 and PM10 (winter > spring > summer). Owing to the variation of meteorological conditions, the proportion of different mercury species in TPM followed different seasonal trends. In contrast to RPM, the percentage of both HPM and EPM in PM2.5 was higher than in PM10.
اظهر المزيد [+] اقل [-]Assessment of bioavailable hydrocarbons in Pribilof Island rock sandpiper fall staging areas and overwintering habitat
2016
Nesvacil, Kelly | Carls, Mark | Holland, Larry | Wright, Sadie
At present, significant adverse hydrocarbon influence on the Pribilof Island rock sandpiper (Calidris ptilocnemis ptilocnemis) is unlikely. Almost the entire population overwinters in Cook Inlet and breeds on four Bering Sea islands. Passive samplers deployed several times in a three year period and corresponding sediment and soft tissue samples on St. Paul Island and in Cook Inlet generally accumulated small quantities of polycyclic aromatic hydrocarbons (PAHs). Composition was consistent with oil in <15% of the passive samplers and rarely in soft tissue. Total PAH concentrations in corresponding sediment were very low (<42ng/g dry weight); composition was consistent with oil in 39% of these samples and biomarker composition confirmed this on St. Paul Island. However, composition was dominated by normal alkanes from natural sources.
اظهر المزيد [+] اقل [-]An in-depth survey of the oil spill literature since 1968: Long term trends and changes since Deepwater Horizon
2016
Murphy, David | Gemmell, Brad | Vaccari, Liana | Li, Cheng | Bacosa, Hernando | Evans, Meredith | Gemmell, Colbi | Harvey, Tracy | Jalali, Maryam | Niepa, Tagbo H.R.
In order to characterize the state of oil spill research and describe how the field has changed since its inception in the 1960s and since the Deepwater Horizon spill in 2010, we examined approximately 10% of oil spill literature (1255 of over 11,000 publications) published from 1968 to 2015. We find that, despite its episodic nature, oil spill research is a rapidly expanding field with a growth rate faster than that of science as a whole. There is a massive post-Deepwater Horizon shift of research attention to the Gulf of Mexico, from 2% of studies in 2004–2008 to 61% in 2014–2015, thus ranking Deepwater Horizon as the most studied oil spill. There is, however, a longstanding gap in research in that only 1% of studies deal with the effects of oil spills on human health. These results provide a better understanding of the current trends and gaps within the field.
اظهر المزيد [+] اقل [-]Loss and self-restoration of macrobenthic diversity in reclamation habitats of estuarine islands in Yangtze Estuary, China
2016
Lv, Weiwei | Liu, Zhiquan | Yang, Yang | Huang, Youhui | Fan, Bin | Jiang, Qichen | Zhao, Yunlong
In this study, macrobenthic diversity data were collected from intertidal habitats of island wetlands in Yangtze Estuary before and after reclamation. Three survey regions based on habitat features were investigated: protected region, normal region, and self-restored region. The pattern of diversity variation showed a sharp decrease in reclamation sites and an obvious increase in vegetated sites of the self-restored region before and after reclamation. A declining trend in habitat health was observed in reclamation sites, but the degree of perturbation was relatively weaker in protected region than in normal region. The vegetated site showed a better self-restoration of biodiversity than the bald site. These results suggest that reclamation may have a negative influence on biodiversity and habitat health status in the intertidal wetland. Also, there is a possibility of self-restoration in tidal flats disturbed by reclamation and the resistance effect in nature reserve may reduce the disturbances resulting from reclamation.
اظهر المزيد [+] اقل [-]Spatiotemporal characteristics and health effects of air pollutants in Shenzhen
2016
Wu, Yongsheng | Zhang, Fengying | Shi, Yu | Pilot, Eva | Lin, Lanyu | Fu, Yingbin | Krafft, Thomas | Wang, Wuyi
In this study, spatiotemporal patterns and health effects in all-cause mortality of air pollutants (CO, NO2, and SO2) during 2013 in Shenzhen were investigated. Spatiotemporal characteristics of air quality index (AQI) and air quality are also addressed. The results show that daily averages were 10.9 μg/m3 for SO2, 39.6 μg/m3 for NO2, and 1.2 mg/m3 for CO. Daily AQI ranged from 24 to 179. There were approximately 39 days of air pollution in Shenzhen. NO2 was the third major air pollutant. Monthly/hourly average AQI and concentrations of NO2 and SO2 in the city center area were higher than in tourist areas. Annual AQI and NO2 concentration were higher in western parts of Shenzhen, whereas SO2 was higher in eastern portions. The lowest CO concentration was in the Luohu District. Relative risks of mortality number increased with SO2/NO2 levels. When SO2/NO2 concentration changed, female individuals were more sensitive than male individuals, and people aged older than 65 years were more affected than younger people.
اظهر المزيد [+] اقل [-]Estimating ozone and secondary PM2.5 impacts from hypothetical single source emissions in the central and eastern United States
2016
Baker, Kirk R. | Kotchenruther, Robert A. | Hudman, Rynda C.
Secondary pollutant impacts from emissions of single sources may need to be assessed to satisfy a variety of regulatory requirements including the Clean Air Act New Source Review and Prevention of Significant Deterioration programs and the National Environmental Policy Act. In this work, single source impacts on O3 and secondary PM2.5 are estimated with annual 2011 photochemical grid model simulations where new hypothetical sources are added to the central and eastern United States with varying precursor emission rates and emission release heights. Impacts from these hypothetical sources are tracked with photochemical grid model source apportionment. Single source impacts on downwind 8-hr maximum O3 tend to increase as emissions of NOX or VOC increase. Downwind impacts on PM2.5 sulfate and nitrate also tend to increase as emissions of SO2 and NOX increase. For all secondary pollutants, impacts from these hypothetical sources tend to decrease as distance from the source increases. However, peak impacts on O3 and secondary PM2.5 are not at the facility fence-line but typically within 50–100 km depending on the emissions rate, precursor pollutant, and emissions release point. Downwind impacts are not uniform directionally from these sources due to varying downwind availability of chemical reactants and prevailing meteorology. Peak impacts for O3 (∼15 ppb) and PM2.5 sulfate (∼8 μg/m3) were within 50 km of these hypothetical sources and peak impacts for PM2.5 nitrate (∼1 μg/m3) were within 125 km. The daily maximum 8-hr O3 and maximum daily average PM2.5 sulfate and nitrate ion impacts for the new hypothetical sources modeled here are generally consistent with those reported in literature. Additional assessments of single source impacts on secondary pollutants are still needed to provide a more comprehensive assessment of different source types and source environments.
اظهر المزيد [+] اقل [-]Statistical assessment of respirable and coarser size ambient aerosol sources and their timeline trend profile determination: A four year study from Delhi
2016
Yadav, Shweta | Tandon, Ankit | Tripathi, Jayant K. | Yadav, Sudesh | Attri, Arun K.
A reliable identification of sources and their relative time dependent contributions to ambient aerosol load is an important air pollution research problem. Given the inherent complexity of contributing sources in urban/mega-cities, an appropriate statistical investigation is needed to characterize sources and to understand their timeline trend profiles. Daily average ambient particulate matter (PM) loads, PM10 (aerodynamic diameter <10 μm) and coarser particulate matter (CPM: aerodynamic diameter >10 μm) were collected once a week over 4 years at a receptor site in Delhi. The samples were analyzed to quantify the presence of 17 marker elements. Time series data of PM loads, and that of associated marker elements was subjected to Positive Matrix Factorization (PMF) to identify sources and to quantify their contributions to each PM fraction with reference to the associated marker elements. The resolved time series data of each contributing source was further subjected to Ensemble Empirical Mode Decomposition (EEMD) analysis to extract their timeline trend profile over four years in CPM and PM10 load. Three sources contributed to the CPM load: anthropogenic (15%), primary crustal (59%), and fine crustal dust (26%). Four sources contributed to the PM10 load: coarser grain crustal material (9%), fine grain crustal material (12%), industrial and vehicular emissions (23%), and wind assisted transport and re-suspension of surface dust (56%). The timeline trend of sources contributions to CPM and PM10 displayed a non-linearity. The unique composite-PM10 source contributed maximum to the ambient PM10 load. Distinct underlying processes of this source involved convective re-suspension and city-wide cleaning associated upliftment of surface deposits back into the ambient environment.
اظهر المزيد [+] اقل [-]Trace Elements in Soils around Coal Mines: Current Scenario, Impact and Available Techniques for Management
2016
Sahoo, Prafulla Kumar | Equeenuddin, Sk. Md | Powell, M. A.
The present paper reviewed the average concentrations of trace elements in soils near coal mine areas from various cities/countries to provide a current global summary of this issue. The contamination of soils was assessed by using global reference materials and various contamination indices. The results show that the average concentrations of trace elements varied widely: As (0.5–38.3 mg/kg), Mn (86–3,700 mg/kg), Zn (1.5–296 mg/kg), Cu (0.5–110 mg/kg), Cr (17.5–954 mg/kg), Ni (4.3–390 mg/kg), Pb (0.5–433 mg/kg), Cd (0.02–4.48 mg/kg), and Hg (0.02–0.69 mg/kg). Most of these values are higher than the average world background soils and upper continental crust (UCC). The geo-accumulation (I gₑₒ) and contamination factor (CF) indices show that the contamination levels of Ni and Pb are higher than other elements. The potential ecological risk index (E ᵢ) suggests a high risk from Cd, especially in the Tabagi River watershed in Brazil and Ledo coal mines in India, and Hg, especially in Oltu (Turkey). The degree of contamination index (C d) reveals that the soils from Barapukuria (Bangladesh), Ledo (India), Ptolemais-Amynteon (Greece), and the Tibagi River (Brazil) have a higher degree of contamination than other sites. To control soil contamination, effective monitoring and legislative measures must be taken immediately. For the long term, various physical, chemical, and biological methods should be implemented. Although the selection of suitable methods is site-specific based on the extent and nature of contamination, in general, phytoremediation seems to be more beneficial and cost-effective than physical/chemical techniques.
اظهر المزيد [+] اقل [-]Predicting pollutant concentrations in the water column during dredging operations: Implications for sediment quality criteria
2016
Wasserman, Julio Cesar | Wasserman, Maria Angélica V. | Barrocas, Paulo Rubens G. | Almeida, Aline Mansur
The development of new dredging techniques that can reduce, or at least predict, the environmental impacts, is in high demand by governments in developing countries. In the present work, a new methodology was developed, to evaluate the level of metals contamination (i.e. cadmium, lead and zinc) of the water column, during a dredging operation. This methodology was used to evaluate the impacts of the construction of a new maritime terminal in Sepetiba Bay, Brazil. The methodology quantifies the amount of resuspended sediments and calculates the expected contaminants concentrations in the water column. The results indicated that sediment quality criteria were not compatible with water quality criteria, because the dredging of contaminated sediments does not necessarily yield contaminated water. It is suggested that the use of sediment quality criteria for dredging operations might be abandoned, and the methodology presented in this study applied to assess dredging's environmental impacts, predicting water contamination levels.
اظهر المزيد [+] اقل [-]Regional variability in bed-sediment concentrations of wastewater compounds, hormones and PAHs for portions of coastal New York and New Jersey impacted by hurricane Sandy
2016
Phillips, Patrick J. | Gibson, Catherine A. | Fisher, Shawn C. | Fisher, Irene J. | Reilly, Timothy J. | Smalling, Kelly L. | Romanok, Kristin M. | Foreman, William T. | ReVello, Rhiannon C. | Focazio, Michael J. | Jones, Daniel K.
Bed sediment samples from 79 coastal New York and New Jersey, USA sites were analyzed for 75 compounds including wastewater associated contaminants, PAHs, and other organic compounds to assess the post-Hurricane Sandy distribution of organic contaminants among six regions. These results provide the first assessment of wastewater compounds, hormones, and PAHs in bed sediment for this region. Concentrations of most wastewater contaminants and PAHs were highest in the most developed region (Upper Harbor/Newark Bay, UHNB) and reflected the wastewater inputs to this area. Although the lack of pre-Hurricane Sandy data for most of these compounds make it impossible to assess the effect of the storm on wastewater contaminant concentrations, PAH concentrations in the UHNB region reflect pre-Hurricane Sandy conditions in this region. Lower hormone concentrations than predicted by the total organic carbon relation occurred in UHNB samples, suggesting that hormones are being degraded in the UHNB region.
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