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Результаты 861-870 из 2,492
Atmospheric hexachlorobenzene determined during the third China arctic research expedition: Sources and environmental fate
2014
Wu, Xiaoguo | Lam, James C.W. | Xia, Chonghuan | Kang, Hui | Xie, Zhouqing | Lam, Paul K.S.
In July to September 2008, air samples were collected aboard a research expedition icebreaker, Xuelong (Snow Dragon), under the support of the 2008 Chinese Arctic Research Expedition Program. All the air samples were analyzed for determination of the concentrations of Hexachlorobenzene (HCB). The levels of HCB ranged from 24 to 180pg m−3, with an average concentration of 88pg m−3. Generally, HCB were more uniform than other organchlorine pollutants in the North Pacific Ocean and the Arctic Ocean. Geographically, the average concentrations of HCB from high to low were in the following order: the Central Arctic Ocean (110±57pg m−3), the Chukchi and Beaufort Seas (93±29pg m−3), the East Asia (75±49pg m−3) and the North Pacific Ocean (69±38pg m−3). In the East Asia Sea and the North Pacific Ocean, both primary and secondary emissions of HCB from the nearby continents and/or oceans might contribute to the atmospheric HCB. In the Arctic, intense sea–ice melting in the summer of 2008 might result in the remobilization of HCB and enhance its atmospheric levels in this region.
Показать больше [+] Меньше [-]Macrobenthic diversity in protected, disturbed, and newly formed intertidal wetlands of a subtropical estuary in China
2014
Lv, Weiwei | Ma, Chang-an | Huang, Youhui | Yang, Yang | Yu, Ji | Zhang, Mingqing | Zhao, Yunlong
In this study, intertidal macrobenthic diversity in protected, disturbed, and newly formed wetlands of Yangtze estuary was assessed using PRIMER 5.2 based on species diversity and species relatedness. We observed high diversity in nature reserves and low diversity in adjacent disturbed and newly formed wetlands. These diversity data were then integrated with historical data to detect the variation in macrobenthic diversity over the past two decades. The integrated data indicated that the intertidal macrobenthic diversity sharply decreased in heavy reclamation tidal flats whereas markedly increased in non-disturbed nature reserve and newly formed wetland. Benthic health was observed with the departure degree of average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) from the simulated 95% confidence funnel. All the habitats were subjected to different levels of human interference, except Jiuduansha and Beigangbeisha. The degradation of intertidal wetland in Yangtze estuary was mainly attributed to land reclamation, overgrazing, and overfishing.
Показать больше [+] Меньше [-]Comparison of metal accumulation in the azooxanthellate scleractinian coral (Tubastraea coccinea) from different polluted environments
2014
Chan, Isani | Hung, Jia-Jang | Peng, Shao-Hung | Tseng, Li-Chun | Ho, Tung-Yuan | Hwang, Jiang-Shiou
The response of metal accumulation in coral Tubastraea coccinea to various degrees of metal enrichment was investigated from the Yin-Yang Sea (YYS) receiving abandoned mining effluents, the Kueishan Islet (KI) hydrothermal vent field, and the nearshore area of remoted Green Island (GI). The concentrations of most dissolved metals were highest in seawater at YYS, followed by KI, and then GI, showing the effects of anthropogenic and venting inputs on metal levels. Five metals (Co, Fe, Mn, Ni, and Zn) yielded significant differences (p<0.05) among the skeleton samples. We identified similar patterns in the metal–Ca ratios, indicating that the elevated metals in skeletons was a consequence of external inputs. The coral tissues were relatively sensitive in monitoring metal accumulation, showing significant differences among three locations for Cd, Co, Cu, Fe, Pb, Ni, and Zn. Specific bioconcentration factors provided strong support for the differential metal accumulation in skeletons and tissues.
Показать больше [+] Меньше [-]Spatial patterns of metals, PCDDs/Fs, PCBs, PBDEs and chemical status of sediments from a coastal lagoon (Pialassa Baiona, NW Adriatic, Italy)
2014
Guerra, Roberta | Pasteris, Andrea | Lee, Seok-hyung | Park, No-jin | Ok, Gon
The European Water Framework Directive (WFD) establishes a framework for the protection and improvement of all water bodies including transitional waters; its final objective is to achieve at least ‘good status’ by 2015. In the present work, a hierarchical sampling design was applied to analyze the influence of anthropogenic inputs on the spatial distribution of metals, polychlorinated dibenzo-p-dioxins (PCDDs) dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in sediment at four areas in Pialassa Baiona coastal lagoon. In order to assess the chemical status, levels of priority substances and other pollutants were compared with the recently developed national Environmental Quality Standards (EQS) and site specific background levels for metals. Levels of mercury and PCBs were particularly high and exceeded their national EQS values at all sampled areas, thus not contributing to the achievement of a good chemical status of this transitional water body according to the WFD classification.
Показать больше [+] Меньше [-]Carcinogenic and mutagenic potencies for different PAHs sources in coastal sediments of Shandong Peninsula
2014
Li, Guo Liang | Lang, Yin-hai | Gao, Mao-sheng | Yang, Wei | Peng, Peng | Wang, Xiao-mei
In this study, sources of PAHs in coastal sediments of Shandong Peninsula were apportioned using the chemical mass balance (CMB) model, and source apportionment of carcinogenic and mutagenic potencies was conducted combining CMB with the formula of benzo(a)pyrene carcinogenic equivalent (BaPTEQ) and BaP mutagenic equivalent (BaPMEQ) concentration. Total concentrations of sixteen PAHs in sediment ranged from 181.2ngg−1 to 303.6ngg−1, and concentrations of eight carcinogenic PAHs (cPAHs) varied from 98.8ngg−1 to 141.1ngg−1. The BaP played a dominant role for carcinogenic and mutagenic potencies of PAHs, although the IND showed the highest concentration level. The vehicular sources made the highest contribution to BaPTEQ (57.7%) and BaPMEQ (55.5%), while petrogenic source, the highest contributor for PAHs (39.4%), provided the lowest contribution to BaPTEQ (1.1%) and BaPMEQ (1.5%). Besides, the ecotoxicological evaluation, based on Sediment Quality Guidelines (SQGs), showed low ecological risks generally.
Показать больше [+] Меньше [-]Trace metal concentrations in Spartina densiflora and associated soil from a Patagonian salt marsh
2014
Idaszkin, Yanina L. | Bouza, Pablo J. | Marinho, Carmen H. | Gil, Mónica N.
The objectives of this study were to (i) assess in situ trace metal concentrations in soil and in Spartina densiflora in a Patagonian salt marsh (Rawson, Chubut, Argentina) and (ii) investigate the relationship between trace metal concentrations in soils and in plants to improve our knowledge regarding the ability of S. densiflora to take up and accumulate trace metals from the soil within its native region. Our results indicate that the soil and S. densiflora exhibit low metal concentrations in the Rawson salt marsh. S. densiflora accumulates Zn in below- and above-ground plant structures and Cr in below-ground parts. These results suggest at the time of this study there is scarce human impact associated with metals in the Rawson salt marsh.
Показать больше [+] Меньше [-]Health–risk assessment of workers exposed to flour dust: A cross–sectional study of random samples of bakeries workers
2014
Moghaddasi, Yousef | Mirmohammadi, Seyedtaghi | Ahmad, Anees | Etemadi Nejad, Syavash | Yazdani, Jamshid
The objectives of this study were to measure exposure to dust in the small bakery shops, to define the determinants of occupational asthma, and to propose control measures for this. The study included bakery workers of one hundred bakeries (the cases; n=200, the controls; n=20). Their individual information was obtained by a simple questionnaire based on “Ear–Nose–Throat” (ENT) work–related symptoms such as coughing, wheezing, chest tightness and irritations. Subjects were considered as “possible occupational asthma cases”. Medical visit was carried out to complete clinical and lung function investigations for these subjects. The mean flour dust concentration in the current study was 28mg/m3. Fifty six of bakery workers had work related symptoms significantly higher than those in controls. The spirometric results illustrated that the workers with experience of less than five years are not affected as there was no significant difference between exposed cases and controls in mean forced expiratory volume in one second (FEV1) or forced vital capacity (FVC) percent determined. But workers with experience of five years or more showed significantly lower mean FEV1 and FVC percent predicted when compared with controls. The results of lung function test for subjects demonstrated that the flour dust pollution adversely affects on main lung function parameters, such as FVC and FEV1. This study confirms that the risk of pulmonary disease among flour dust exposed workers is higher than the unexposed control subjects.
Показать больше [+] Меньше [-]Field evaluation of a near–real time elemental monitor and identification of element sources observed at an air monitoring supersite in Korea
2014
Park, Seung–Shik | Cho, Sung–Yong | Jo, Mi–Ra | Gong, Bu–Joo | Park, Jin–Soo | Lee, Suk–Jo
Ambient measurements of elemental species concentrations were made using an online elemental monitor at an air pollution monitoring station in Gwangju, Korea to evaluate the performance of the monitor for near–real time PM2.5 elemental monitoring and identify possible sources of the observed elements. This study also demonstrates the utility of integrating hourly elemental data with the meteorological data to better understand the sources of elements. Good agreement between the online and filter–based measurements was obtained for the elements studied, with an R2 of 0.73–0.97 and regression slopes of 0.84–2.37, suggesting the potential use of the online monitor to observe temporal variations in anthropogenic aerosol particles. Atmospheric element concentration levels studied were 2–20 times greater than their background levels when pollution plumes coming from industrial areas had impacted the site. Examination of the elements data revealed several short spikes of elements that are associated with local industrial emissions and road dusts. For the haze episodes observed over the study period, the element K was significantly influenced by biomass burning emissions with some impacts from soil dusts and industrial activities. Based on the wind direction and wind speed data, As/Se, Se/SO42−, and correlations among Se, As, Pb, SO2, and SO42−, it is suggested that the observed As and Se were significantly impacted by local anthropogenic sources and long–range transport of aerosols, rather than local coal combustion or coke emissions. Conditional probability functions were applied to identify likely local emission source locations of the elements observed at the site, indicating that the elements contributions were from the southwest and northeast directions, where two industrial areas and an express highway are located. Results from principal component analysis indicate that the observed concentrations of the element species were likely attributed to road dust/local industrial emissions, oil combustion, and metal processing.
Показать больше [+] Меньше [-]Distributions of polychlorinated biphenyls in the Daliao River estuary of Liaodong Bay, Bohai Sea (China)
2014
Men, Bin | He, Mengchang | Tan, Li | Lin, Chunye
The distributions of 41 polychlorinated biphenyls (PCBs) were determined in the aqueous phase, suspended particulate matter (SPM), and sediment of the Daliao River estuary in Liaodong Bay, Bohai Sea (China). The total PCB concentrations ranged from 5.51 to 40.28ngL−1 in the surface water, from 6.78 to 66.55ngL−1 dry weight in the SPM, and from 0.83 to 7.29ngg−1 dry weight in the sediment. The PCB concentrations in water, SPM, and sediment were moderate relative to those reported for other estuary and marine systems around the world. Sedimentary PCB concentrations decreased offshore due to the active deposition of laterally transported river-borne particles. The predominance of the highly chlorinated congeners for the water, SPM, and sediment samples are an indication of either a lack of degradation or the presence of nearby or recent releases into the environment.
Показать больше [+] Меньше [-]Seagrass importance for a small-scale fishery in the tropics: The need for seascape management
2014
Torre-Castro, Maricela de la | Di Carlo, Giuseppe | Jiddawi, Narriman S.
Small-scale fisheries (SSF) in tropical seascapes (mosaics of interconnected mangroves, seagrasses and corals) are crucial for food and income. However, management is directed mostly to corals and mangroves. This research analyzes the importance of seagrasses compared to adjacent ecosystems in Chwaka Bay, Zanzibar, Tanzania. Using fish landings; the study investigated: location of fishing effort, fish production (biomass and species), and monetary benefits (aggregated value and per capita income). Seagrasses were the most visited grounds providing highest community benefits. Per capita benefits were equivalent to those from corals and mangroves. All three habitats provided income just above extreme poverty levels; however catches from seagrass appeared more stable. Seagrass are key ecosystems supporting SSF and protection and management are urgently needed. Adoption of a seascape approach considering all ecosystems underpinning SSF and the social aspects of fishing and a shift in emphasis from pure conservation to sustainable resource management would be desirable.
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