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Resultados 1171-1180 de 3,208
Heavy metal spatial variability and historical changes in the Yangtze River estuary and North Jiangsu tidal flat Texto completo
2015
Liu, Zhiyong | Pan, Shaoming | Sun, Zhuyou | Ma, Renfeng | Chen, Lanhua | Wang, Yanlong | Wang, Shuao
This research focuses on the spatial and temporal patterns of heavy metals from the Yangtze River estuary and the tidal flat of north Jiangsu. Most heavy metals in the surficial sediments after normalization to Ti decreased seaward at the Yangtze River estuary. The core records showed that the heavy metal variations in the last 50years were primarily linked to natural weathering input of trace elements. However, significant heavy metal pollution (mainly Ni, Pb, Cd, Cu and As) were in the two study areas, with anthropogenic inventories accounting for 23–40% percent of the total pollution. Sequential extraction showed that Pb, Cu and Ni were present largely in the non-residual fraction, which indicated the potential bioavailability in the study areas. The SEM/EDS together with sequential extraction facilitated the easy tracing of the origin/sources of heavy metals in a simple way in the estuary and the tidal flat.
Mostrar más [+] Menos [-]Microplastic contamination in brown shrimp (Crangon crangon, Linnaeus 1758) from coastal waters of the Southern North Sea and Channel area Texto completo
2015
Devriese, Lisa I. | van der Meulen, Myra D. | Maes, Thomas | Bekaert, Karen | Paul Pont, Ika | Frère, Laura | Robbens, Johan | Vethaak, A Dick
This study assessed the capability of Crangon crangon (L.), an ecologically and commercially important crustacean, of consuming plastics as an opportunistic feeder. We therefore determined the microplastic content of shrimp in shallow water habitats of the Channel area and Southern part of the North Sea. Synthetic fibers ranging from 200μm up to 1000μm size were detected in 63% of the assessed shrimp and an average value of 0.68±0.55microplastics/g w. w. (1.23±0.99microplastics/shrimp) was obtained for shrimp in the sampled area. The assessment revealed no spatial patterns in plastic ingestion, but temporal differences were reported. The microplastic uptake was significantly higher in October compared to March. The results suggest that microplastics >20μm are not able to translocate into the tissues.
Mostrar más [+] Menos [-]Occurrence and amount of microplastic ingested by fishes in watersheds of the Gulf of Mexico Texto completo
2015
Phillips, Melissa B. | Bonner, Timothy H.
Ingestion of microplastics by fishes could be an emerging environmental crisis because of the proliferation of plastic pollution in aquatic environments. Microplastics in marine ecosystems are well documented, however only one study has reported percent occurrence of microplastics in freshwater fishes. The purpose of this study was to quantify the occurrences and types of microplastics ingested by fishes within several freshwater drainages of the Gulf of Mexico and an estuary of the Gulf of Mexico. Among 535 fishes examined in this study, 8% of the freshwater fishes and 10% of the marine fishes had microplastics in their gut tract. Percentage occurrence of microplastics ingested by fishes in non-urbanized streams (5%) was less than that of one of the urbanized streams (Neches River; 29%). Percent occurrence of microplastics by habitat (i.e., benthic, pelagic) and trophic guilds (herbivore/omnivore, invertivore, carnivore) were similar. Low but widespread occurrences among drainages, habitat guilds, and trophic guilds indicate proliferation of plastic pollution within watersheds of the Gulf of Mexico, but consequences to fish health are unknown at this time.
Mostrar más [+] Menos [-]Ecological risk assessments and context-dependence analysis of heavy metal contamination in the sediments of mangrove swamp in Leizhou Peninsula, China Texto completo
2015
Liu, Jing | Ma, Keming | Qu, Laiye
Sediments in eight types of mangroves were sampled in the Leizhou Peninsula. Heavy metals were analyzed to investigate the effects on metal distribution of mangrove communities, to evaluate contamination levels, identify sources and relationships between the two. Results showed that mangrove communities have effects on most heavy metal distributions in sediments, especially in the sediment with shrub communities of Aegiceras corniculatum where the contents of many metals are highest. As, Cr and Ni were identified as metal pollutants of primary concern, while Cd was of no concern. Zn, Pb, As mainly originated from anthropogenic source while the other metals are geogenic. Heavy metal distributions were affected by the independent and joint effects of landscape and sediment context; landscape context explains more variations in heavy metals than does sediment physicochemical variables. Total sulfur, total phosphorus and total potassium in sediment, and the existence of paddy field and forest land within 2000m around the sampling sites are significant variables also.
Mostrar más [+] Menos [-]The environment quality of heavy metals in sediments from the central Bohai Sea Texto completo
2015
Liu, Ming | Zhang, Aibin | Liao, Yongjie | Chen, Bin | Fan, Dejiang
The heavy metals (Cu, Co, Ni, Zn, Cr, Pb, Cd) in surface and core sediments from the central Bohai Sea were analyzed to evaluate the temporal/spatial distribution and pollution status. Cd exhibited gradual increase vertically, while others were stable or declined slightly in core sediments. In surface sediments, metals showed higher values in ‘central mud area of the Bohai Sea’ and the coastal area of the Bohai Bay. Cd and Pb also had high levels in the northeastern part of Bohai Sea. Both the contamination factors (CFs) and the geo-accumulation index (Igeo) indicated that Cu, Co, Ni, and Cr were not at pollution levels, while Pb, Zn, and Cd indicated moderate contamination. Compared with sediment quality guidelines (SQGs), Cu, Zn, Cr, Pb, and Cd were likely to produce occasional adverse biological effects, while Ni showed possible ecotoxicological risks. The combined levels of the metals have a 21% probability of being toxic.
Mostrar más [+] Menos [-]Trace metal enrichment and organic matter sources in the surface sediments of Arabian Sea along southwest India (Kerala coast) Texto completo
2015
Sreekanth, Athira | Mrudulrag, S.K. | Cheriyan, Eldhose | Sujatha, C.H.
The geochemical distribution and enrichment of trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were determined in the surface sediments of Arabian Sea, along southwest India, Kerala coast. The results of geochemical indices indicated that surficial sediments of five transects are uncontaminated with respect to Mn, Zn and Cu, uncontaminated to moderately contaminated with Co and Ni, and moderately to strongly contaminated with Pb. The deposition of trace elements exhibited three different patterns i) Cd and Zn enhanced with settling biodetritus from the upwelled waters, ii) Pb, Co and Ni show higher enrichment, evidenced by the association through adsorption of iron–manganese nodules onto clay minerals and iii) Cu enrichment observed close to major urban sectors, initiated by the precipitation as Cu sulfides. Correlation, principal component analysis (PCA) and cluster analysis (CA) were used to confirm the origin information of metals and the nature of organic matter composition.
Mostrar más [+] Menos [-]Plastic and metal ingestion in three species of coastal waterfowl wintering in Atlantic Canada Texto completo
2015
English, Matthew D. | Robertson, Gregory J. | Avery-Gomm, Stephanie | Pirie-Hay, Donald | Roul, Sheena | Ryan, Pierre C. | Wilhelm, Sabina I. | Mallory, Mark L.
Relatively little attention has been paid to the occurrence of anthropogenic debris found in coastal species, especially waterfowl. We examined the incidence of ingested plastic and metal in three waterfowl species wintering in Atlantic Canada: American black ducks (Anas rubripes) and mallards (A. platyrhynchos), two species that use marine and freshwater coastal habitats for foraging in the winter, and common eider (Somateria mollissima), a coastal marine species that feeds on intertidal and subtidal benthic organisms. Plastic was found in the stomachs of 46.1% (6/13) of mallards and 6.9% (6/87) of black ducks, the first report of ingested anthropogenic debris in these species, while 2.1% (1/48) of eider stomachs contained plastic. Metal was found in the stomachs of 30.8% (4/13) of mallards, 2.3% (2/87) of black ducks, and in 2.1% (1/48) of eiders. Our results indicate that species using coastal marine and freshwater environments are exposed to and ingest anthropogenic debris.
Mostrar más [+] Menos [-]Biotope map of the German Baltic Sea Texto completo
2015
Schiele, Kerstin S. | Därr, Alexander | Zettler, Michael L. | Friedland, René | Tauber, Franz | von Weber, Mario | Voss, Joachim
Full-coverage maps on the distribution of marine biotopes are a necessary basis for Nature Conservation and Marine Spatial Planning. Yet biotope maps do not exist in many regions. We are generating the first full-coverage biotope map for the German Baltic Sea according to the HELCOM Underwater biotope and habitat classification system (HUB). Species distribution modelling is applied to create full-coverage spatial information of biological features. The results of biomass modelling of twelve target taxa and presence/absence modelling of three target taxa enabled the identification of biological levels up to HUB level 6. Environmental data on bathymetry, light penetration depth and substrate are used to identify habitat levels. HUB biotope levels were combined with HUB habitat levels to create a biotope map. Altogether, 68 HUB biotopes are identified in the German Baltic Sea. The new biotope map combining substrate characteristics and biological communities will facilitate marine management in the area.
Mostrar más [+] Menos [-]Modelling the fate of micropollutants in the marine environment using passive sampling Texto completo
2015
Claessens, Michiel | De Laender, Frederik | Monteyne, Els | Roose, Patrick | Janssen, Colin R.
Polydimethylsiloxane sheets were used to determine freely dissolved concentrations (Cdiss) of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the Belgian coastal zone. Equilibrium models were used to predict the whole water concentrations (Cww) of these compounds as well as their concentrations in sediment, suspended particulate matter (SPM) and biota. In general, contaminant concentrations were predicted well for whole water and biota. Cww was increasingly underpredicted as Koc increased, possibly because of the presence of black carbon. Concentrations in biota were overestimated by the equilibrium approach when logKow exceeded 6.5, suggesting an increasing role of transformation processes. Concentrations of PAHs and PCBs in sediment and SPM were consistently underpredicted although a good correlation between measured and predicted values was observed. This was potentially due to the use of experimental Koc values which have been found to underestimate partitioning of hydrophobic substances to sediment in field studies.
Mostrar más [+] Menos [-]Seasonal variation of fine particulate matter in residential micro–environments of Lahore, Pakistan Texto completo
2015
Sidra, Safdar | Ali, Zulfiqar | Ahmad Nasir, Zaheer | Colbeck, I. (Ian)
Shifting seasons greatly influence the use and management practices in residential built environments which subsequently affect the level of exposure to various pollutants indoors. The levels of fine particulate matter (PM2.5) were monitored in fifteen households of Lahore, Pakistan during different seasons. DustTrak aerosol monitors (model 8520, TSI Inc.) were run simultaneously in the kitchens and living rooms of the selected sites for seventy two hours each. To aid analysis, houses were categorized in three groups according to floor area. For non–smoking houses there was little variation between 24h average PM2.5 concentrations in kitchens (270 to 295μg/m3) although there was an increase in concentrations in living rooms as floor area increased. Across all houses the average PM2.5 concentration was observed to vary during the seasons. In the kitchens the average PM levels were 326μg/m3 during the spring falling to 133μg/m3 in summer, 180μg/m3 in monsoon, 395μg/m3 in autumn and 448μg/m3 during the winter. Similarly, in the living rooms, the mean PM levels observed were 190μg/m3 in spring, 101μg/m3 in summer, 158μg/m3 in monsoon, 458μg/m3 in autumn and 590μg/m3 in winter. Factors contributing towards these levels were cooking (involving frequent frying), floor sweeping, and also movement of the occupants. Smoking at two sites and use of gas heaters during the winter were also identified as contributing sources. Apart from these sources, ventilation was identified to be the most singular attributing factor to the above mentioned variations in PM levels. Ventilation during the warm season ranged from 3.51 air changes per hour (ACH) to 7.68 ACH. On the contrary, ventilation decreased during the autumn and winter season (2.5 to 5.64 ACH) and this resulted in an accumulation of PM indoors. The levels of fine particulate matter were observed to be 3 to 23 times higher than the WHO established standard of 25μg/m3.
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