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Resultados 1291-1300 de 3,991
PCBs and OCPs in fish along coastal fisheries in China: Distribution and health risk assessment
2016
Pan, Hui | Geng, Jingjing | Qin, Yukun | Tou, Feiyun | Zhou, Junliang | Liu, Min | Yang, Yi
PCBs and OCPs were analyzed in fish (bass) taken along Chinese coastal fisheries. In the bass muscle, PCB, DDT and HCH concentrations were in the range of 1.02–2.2ng/g, 0.44–1.74 and 2.84–106.11ng/gww, respectively. Spatial distribution showed that the concentrations of target contaminants in bass from south fisheries were in general much lower than those from north fisheries in China. The ratios of OCP congeners suggested that technical DDT was not the main input and a recent usage of lindane or old technical HCH residuals could be the source of HCHs. The OCC concentrations in liver (127–442.43ng/gww) from selected samples were 8–12 and 10–14 times higher than those in gills and muscles, respectively. Based on the maximum allowable fish assumption rate (CRlim and CRmm), it could cause human health risk, by consuming bass samples taken from highly contaminated fisheries including QD and ST.
Mostrar más [+] Menos [-]Damage and recovery assessment of the Philippines' mangroves following Super Typhoon Haiyan
2016
Long, Jordan | Giri, Chandra | Primavera, Jurgenne | Trivedi, Mandar
We quantified mangrove disturbance resulting from Super Typhoon Haiyan using a remote sensing approach. Mangrove areas were mapped prior to Haiyan using 30m Landsat imagery and a supervised decision-tree classification. A time sequence of 250m eMODIS data was used to monitor mangrove condition prior to, and following, Haiyan. Based on differences in eMODIS NDVI observations before and after the storm, we classified mangrove into three damage level categories: minimal, moderate, or severe. Mangrove damage in terms of extent and severity was greatest where Haiyan first made landfall on Eastern Samar and Western Samar provinces and lessened westward corresponding with decreasing storm intensity as Haiyan tracked from east to west across the Visayas region of the Philippines. However, within 18months following Haiyan, mangrove areas classified as severely, moderately, and minimally damaged decreased by 90%, 81%, and 57%, respectively, indicating mangroves resilience to powerful typhoons.
Mostrar más [+] Menos [-]Environmental genotoxicity assessment along the transport routes of chemical munitions leading to the dumping areas in the Baltic Sea
2016
Baršienė, Janina | Butrimavičienė, Laura | Grygiel, Włodzimierz | Stunžėnas, Virmantas | Valskienė, Roberta | Greiciūnaitė, Janina | Stankevičiūtė, Milda
The frequencies of micronuclei (MN), nuclear buds (NB) and nuclear buds on filament (NBf) were examined in 660 specimens of herring (Clupea harengus) collected in 2009–2014 at 65 study stations located mainly along the chemical munition transport routes in the Baltic Sea. The frequency of nuclear abnormalities was strongly increased in herring caught at four stations located close to chemical munition dumping sites, or CWAs — substances (chemical warfare agents) in sediments. Significant increase of MN, NB and NBf was observed in fish caught November 2010–2013 compared to 2009. The most significantly increased genotoxicity responses were recorded in fish caught at stations along CW (chemical weapons) transport routes, close to the Bornholm CW dumping area, in zones with CWAs in sediments and with oil–gas platforms.
Mostrar más [+] Menos [-]Differences in the viability of murine norovirus in different aquatic locations
2016
Takahashi, Hajime | Takahashi, Michiko | Ohshima, Chihiro | Izawa, Yukino | Uema, Masashi | Kuda, Takashi | Kimura, Bon | Noda, Mamoru
Norovirus is detected from shellfish and environmental water more frequently in winter than in other seasons. However, there is no report regarding its viability in actual seawater in situ. We investigated the viability of murine norovirus strain 1 (MNV-1), a surrogate for human norovirus, in 2 types of aquatic locations, a seawater pool carrying oceanic water and inner bay carrying brackish water. Sterilized seawater was inoculated with MNV-1 and enclosed in dialysis tubes, which were placed at the 2 locations. MNV-1 exhibited higher level of viability in brackish than in oceanic water. Factors that influenced the viability of MNV-1 included salt concentration as well as temperature of the seawater. Therefore, based on our findings, coastal brackish water that is routinely used for harvesting or cleaning seafood at fishing ports may promote the viability of norovirus.
Mostrar más [+] Menos [-]The new Landsat 8 potential for remote sensing of colored dissolved organic matter (CDOM)
2016
Slonecker, E Terrence | Jones, Daniel K. | Pellerin, Brian A.
Due to a combination of factors, such as a new coastal/aerosol band and improved radiometric sensitivity of the Operational Land Imager aboard Landsat 8, the atmospherically-corrected Surface Reflectance product for Landsat data, and the growing availability of corrected fDOM data from U.S. Geological Survey gaging stations, moderate-resolution remote sensing of fDOM may now be achievable. This paper explores the background of previous efforts and shows preliminary examples of the remote sensing and data relationships between corrected fDOM and Landsat 8 reflectance values. Although preliminary results before and after Hurricane Sandy are encouraging, more research is needed to explore the full potential of Landsat 8 to continuously map fDOM in a number of water profiles.
Mostrar más [+] Menos [-]Trace element concentration in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India
2016
Kasilingam, K. | Suresh Gandhi, M. | Krishnakumar, S. | Magesh, N.S.
The present work was carried to decipher the trace element accumulation in surface sediments of Palk Strait, southeast coast of Tamil Nadu, India. The elemental concentration and correlation results suggest that fine fractions with CaCO3 content followed by organic matter (OM) of the surface sediments control the trace element accumulation in the study area. In addition, Fe and Mn concentration is chiefly contributed from riverine process and controlled by the mangrove ecosystem. The other elements are derived into marine environment through confluence of untreated industrial pollutants into the river system. The EF result shows that the studied marine sediments are enriched by Ni, Mn, Cu, Pb, Cd, Cr, followed by Zn. The order of the pollution intensity with respect to geo-accumulation index suggests the following ascending order: Ni>Mn>Fe>Cu>Pb>Cd>Cr>Zn. Pollution Load Index (PLI) values reveal that all the samples are falling under moderately to unpolluted category.
Mostrar más [+] Menos [-]Analysis of the spatio-temporal variability of seawater quality in the southeastern Arabian Gulf
2016
Mezhoud, Nahla | Temimi, Marouane | Zhao, Jun | Al Shehhi, Maryam Rashed | Ghedira, Hosni
In this study, seawater quality measurements, including salinity, sea surface temperature (SST), chlorophyll-a (Chl-a), Secchi disk depth (SDD), pH, and dissolved oxygen (DO), were made from June 2013 to November 2014 at 52 stations in the southeastern Arabian Gulf. Significant variability was noticed for all collected parameters. Salinity showed a decreasing trend, and Chl-a, DO, pH, and SDD demonstrated increasing trends from shallow onshore stations to deep offshore ones, which could be attributed to variations of ocean circulation and meteorological conditions from onshore to offshore waters, and the likely effects of desalination plants along the coast. Salinity and temperature were high in summer and low in winter while Chl-a, SDD, pH, and DO indicated an opposite trend. The CTD profiles showed vertically well-mixed structures. Qualitative analysis of phytoplankton showed a high diversity of species without anomalous species found except in Ras Al Khaimah stations where diatoms were the dominating ones.
Mostrar más [+] Menos [-]Spatial–temporal variation, possible source and ecological risk of PCBs in sediments from Songhua River, China: Effects of PCB elimination policy and reverse management framework
2016
Cui, Song | Fu, Qiang | Guo, Liang | Li, Yi-Fan | Li, Tian-xiao | Ma, Wanli | Wang, Min | Li, Wen-long
The spatial variation, possible sources and ecological risk of polychlorinated biphenyls (PCBs) in the sediment from the Songhua River, China were investigated and evaluated in this paper. The total concentration of PCBs ranged from 0.59 to 12.38ng/gdw, with a mean value of 3.82ng/gdw. The seven indicators of PCB concentrations are significantly correlated with the total PCB concentrations (R=0.950, p=0.000). The temporal trend of PCBs in sediments showed that the total PCBs in the Songhua River have decreased since 2008. Point source pollution, discharge of historical usage and industrial sewage, and emissions of unintentionally produced PCBs were the predominant sources in sediment. A risk assessment indicated that most of the sampling sites in the sediment were at low potential ecological risk. The apparent decrease of PCBs in the sediment appeared after the China National Coordination Group for Implementation of the Stockholm Convention was established. A conceptual reverse management framework for PCBs and other organic pollutants was established in this study.
Mostrar más [+] Menos [-]Development of a short-term chronic toxicity test with a tropical mysid
2016
Figuerêdo, Lívia Pitombeira de | Nilin, Jeamylle | Silva, Allyson Queiroz da | Loureiro, Susana | Costa-Lotufo, Letícia Veras
There is an increasing need to develop reliable methodologies for chronic toxicity testing using tropical species. The present work aimed at developing a suitable short-term chronic toxicity test with Mysidopsis juniae using zinc (Zn) and nickel (Ni) as model chemicals and growth (length and dry weight), survival, and egg production (number of females with eggs) as endpoints after seven days of exposure. Survival and growth of newborn M. juniae were affected by chronic exposure to zinc, while nickel affected only survival. For zinc, dry weight was the most sensitive endpoint with significant effects even at the lowest tested concentration (75μgZn·L−1), whereas for nickel, survival was the most sensitive parameter (LC20 of 26μgNi·L−1). Egg production was not affected. M. juniae short-term chronic testing is a sensitive approach to evaluating metal toxicity; further studies are necessary to assess chronic toxicity for others contaminants in the proposed assay.
Mostrar más [+] Menos [-]Manganese Removal from Drinking Water Sources
2016
Tobiason, John E. | Bazilio, Arianne | Goodwill, Joseph | Mai, Xuyen | Nguyen, Chuyen
Manganese (Mn) in drinking water can cause aesthetic and operational problems. Mn removal is necessary and often has major implications for treatment train design. This review provides an introduction to Mn occurrence and summarizes historic and recent research on removal mechanisms practiced in drinking water treatment. Manganese is removed by physical, chemical, and biological processes or by a combination of these methods. Although physical and chemical removal processes have been studied for decades, knowledge gaps still exist. The discovery of undesirable by-products when certain oxidants are used in treatment has impacted physical–chemical Mn removal methods. Understanding of the microorganisms present in systems that practice biological Mn removal has increased in the last decade as molecular methods have become more sophisticated, resulting in increasing use of biofiltration for Mn removal. The choice of Mn removal method is very much impacted by overall water chemistry and co-contaminants and must be integrated into the overall water treatment facility design and operation.
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