细化搜索
结果 1011-1020 的 3,189
Spatial distribution and fate of perfluoroalkyl substances in sediments from the Pearl River Estuary, South China
2015
Gao, Yan | Fu, Jianjie | Meng, Mei | Wang, Yawei | Chen, Baowei | Jiang, Guibin
In this study, 54 sediment samples were collected from the Pearl River Estuary (PRE) in Southern China to study the spatial distribution and patterns of PFASs in this region. PFAS concentrations in the sediment samples ranged from nd (below detection limit) to 2.41ngg−1dw (dry weight) with an average value of 0.79ngg−1dw. PFAS concentrations were higher at the nearshore sampling sites than in the others. Perfluorobutanesulfonate (PFBS) and perfluorohexanesulfonate (PFHxS) were the two dominant compounds among the target PFASs, which may be due to their production and use as PFOS substitutes in the Pearl River Delta (PRD) areas. Significant linear relationships were found between total PFAS concentrations and total organic carbon (TOC) (R=0.30, p<0.05). The preliminary environmental risk assessment indicated that PFOS and PFOA in the regional sediments posed no significant ecological risk to the benthic organisms at present levels.
显示更多 [+] 显示较少 [-]A damage assessment model of oil spill accident combining historical data and satellite remote sensing information: A case study in Penglai 19-3 oil spill accident of China
2015
Wei, Lai | Hu, Zhuowei | Dong, Lin | Zhao, Wenji
Oil spills are one of the major sources of marine pollution; it is important to conduct comprehensive assessment of losses that occur as a result of these events. Traditional methods are required to assess the three parts of losses including cleanup, socioeconomic losses, and environmental costs. It is relatively slow because assessment is complex and time consuming. A relatively quick method was developed to improve the efficiency of assessment, and then applied to the Penglai 19-3 accident. This paper uses an SAR image to calculate the oil spill area through Neural Network Classification, and uses historical oil-spill data to build the relationship between loss and other factors including sea-surface wind speed, and distance to the coast. A multiple regression equation was used to assess oil spill damage as a function of the independent variables. Results of this study can be used for regulating and quickly dealing with oil spill assessment.
显示更多 [+] 显示较少 [-]Depositional record of trace metals and degree of contamination in core sediments from the Mandovi estuarine mangrove ecosystem, west coast of India
2015
Veerasingam, S. | Vethamony, P. | Mani Murali, R. | Fernandes, B.
The concentrations of seven trace metals (Fe, Mn, Cu, Cr, Co, Pb and Zn) in three sediment cores were analysed to assess the depositional trends of metals and their contamination level in the Mandovi estuary, west coast of India. All sediment cores showed enrichment of trace metals in the upper part of core sediments and decrease in concentration with depth, suggesting excess of anthropogenic loading (including mining activities) occurred during the recent past. Scanning electron microscope (SEM) images distinguished the shape, size and structure of particles derived from lithogenic and anthropogenic sources in core sediments. The geo-accumulation index (Igeo) values indicate that Mandovi estuary is ‘moderately polluted’ with Pb, whereas ‘unpolluted to moderately polluted’ with Fe, Mn, Cu, Cr, Co and Zn. The comparative analysis of trace metals revealed that Fe and Mn were highly enriched in the Mandovi estuary compared to all other Indian estuaries.
显示更多 [+] 显示较少 [-]Mercury accumulation in sediments and seabird feathers from the Antarctic Peninsula
2015
Calle, Paola | Alvarado, Omar | Monserrate, Lorena | Cevallos, Juan Manuel | Calle, Nastenka | Alava, Juan José
In an effort to assess the impact of mercury in the Antarctic Peninsula, we conducted ecotoxicological research in this region during the summer of 2012 and 2013. The objectives were to assess: (a) mercury levels in sediment samples; (b) mercury accumulation in Antarctic seabird feathers: Catharacta lonnbergi (brown skua), Pygoscelis papua (gentoo penguin) and Pygoscelis antarctica (chinstrap penguin); and (c) biomagnification (BMF predator/prey) and biota sediment accumulation (BSAF skuas/sediment) factors. Mercury concentrations in sediment were relatively low. Mercury concentrations were significantly higher in brown skuas and gentoo penguins than in chinstrap penguins (2012), and significantly higher in brown skuas than in both penguins (2013). BMF indicated 2–7.5 times greater mercury levels in brown skuas than in penguins. BSAF values suggested an apparent temporal decrease of 18.2% of this ratio from 2012 to 2013. Long-range environmental transport is the likely route of entry of mercury into the Antarctic Peninsula.
显示更多 [+] 显示较少 [-]Effects of light pollution on the emergent fauna of shallow marine ecosystems: Amphipods as a case study
2015
Navarro-Barranco, Carlos | Hughes, Lauren Elizabeth
Light pollution from coastal urban development is a widespread and increasing threat to biodiversity. Many amphipod species migrate between the benthos and the pelagic environment and light seems is a main ecological factor which regulates migration. We explore the effect of artificial lighting on amphipod assemblages using two kind of lights, LED and halogen, and control traps in shallow waters of the Great Barrier Reef. Both types of artificial light traps showed a significantly higher abundance of individuals for all species in comparison to control traps. LED lights showed a stronger effect over the amphipod assemblages, with these traps collecting a higher number of individuals and differing species composition, with some species showing a specific attraction to LED light. As emergent amphipods are a key ecological group in the shallow water environment, the impact of artificial light can affect the broader functioning of the ecosystem.
显示更多 [+] 显示较少 [-]Effect of historical residual hexachlorocyclohexanes and dichlorodiphenyltrichloroethane on bacterial communities in sediment core collected from an estuary in northeastern China by next-generation sequencing
2015
Guo, Jianguo | Zhao, Longhao | Lu, Weihong | Jia, Hongliang | Wang, Luo | Liu, Xianjie | Sun, Yeqing
In this study, we evaluate the influence of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDT) on bacterial communities of sediment core from an estuary formed during the period of 1960–2011. Canonical correspondence analysis showed that o,p′-DDT, o,p′-DDD (mitotane), and depth had important influences on bacterial community distributions (p<0.05). Furthermore, our results found variance explained by all variables was 82.9%, while that by o,p′-DDD was 24.4%, and that of o,p′-DDT was 9.8%, indicating that o,p′-DDD had a greater influence on sediment-dwelling bacteria than o,p′-DDT. Also, bacterial diversity was affected and the Shannon index was significantly negatively correlated with total HCHs (r=−0.579, p<0.05) and total DDTs (r=−0.607, p<0.01), respectively. Furthermore, our results showed that Flavobacteria and Clostridia content can be considered an indicator of pollution of HCHs and DDTs in sediment core samples.
显示更多 [+] 显示较少 [-]Lead distribution in coastal and estuarine sediments around India
2015
Chakraborty, Sucharita | Chakraborty, Parthasarathi | Nath, B Nagender
This study describes the geochemical distribution of lead (Pb) and identifies the critical factors that significantly control Pb distribution and speciation in coastal and estuarine sediments around India by using published data from the literature. Crustal sources influence the abundance of Pb in coastal sediment from the south-east and central-west coast of India. Parts of north-east, north-west, and south-west coast of India were polluted by Pb. Distribution of Pb in sediments, from the north-east and north-west coasts of India, were controlled by Fe–Mn oxyhydroxide mineral phases of the sediments. However, organic carbon (OC) seemed to be a dominant factor in controlling the distribution of Pb in sediments from the central-east and south-west coasts of India. The outcome of this study may help in decision-making to predict the levels of Pb from natural and anthropogenic sources and to control Pb pollution in coastal and estuarine sediments around India.
显示更多 [+] 显示较少 [-]The sub-cellular fate of mercury in the liver of wild mullets (Liza aurata) – Contribution to the understanding of metal-induced cellular toxicity
2015
Araújo, Olinda | Pereira, Patrícia | Cesário, Rute | Pacheco, Mario | Raimundo, Joana
Mercury is a recognized harmful pollutant in aquatic systems but still little is known about its sub-cellular partitioning in wild fish. Mercury concentrations in liver homogenate (whole organ load) and in six sub-cellular compartments were determined in wild Liza aurata from two areas – contaminated (LAR) and reference. Water and sediment contamination was also assessed. Fish from LAR displayed higher total mercury (tHg) organ load as well as in sub-cellular compartments than those from the reference area, reflecting environmental differences. However, spatial differences in percentage of tHg were only observed for mitochondria (Mit) and lysosomes plus microsomes (Lys+Mic). At LAR, Lys+Mic exhibited higher levels of tHg than the other fractions. Interestingly, tHg in Mit, granules (Gran) and heat-denaturable proteins was linearly correlated with the whole organ. Low tHg concentrations in heat stable proteins and Gran suggests that accumulated levels might be below the physiological threshold to activate those detoxification fractions.
显示更多 [+] 显示较少 [-]Effects of simulated eutrophication and overfishing on algae and invertebrate settlement in a coral reef of Koh Phangan, Gulf of Thailand
2015
Stuhldreier, Ines | Bastian, Pepe | Schönig, Eike | Wild, Christian
Coral reefs in the Gulf of Thailand are highly under-investigated regarding responses to anthropogenic stressors. Thus, this study simulated overfishing and eutrophication using herbivore exclosure cages and slow-release fertilizer to study the in-situ effects on benthic algae and invertebrate settlement in a coral reef of Koh Phangan, Thailand. Settlement of organisms and the development of organic matter on light-exposed and shaded tiles were quantified weekly/biweekly over a study period of 12weeks. Simulated eutrophication did not significantly influence response parameters, while simulated overfishing positively affected dry mass, turf algae height and fleshy macroalgae occurrence on light-exposed tiles. On shaded tiles, settlement of crustose coralline algae decreased, while abundances of ascidians increased compared to controls. An interactive effect of both stressors was not observed. These results hint to herbivory as actual key controlling factor on the benthic community, and fleshy macroalgae together with ascidians as potential bioindicators for local overfishing.
显示更多 [+] 显示较少 [-]Marine debris ingestion by Chelonia mydas (Testudines: Cheloniidae) on the Brazilian coast
2015
da Silva Mendes, Sarah | de Carvalho, Robson Henrique | de Faria, Adriana Fonseca | de Sousa, Bernadete Maria
Chelonia mydas is distributed in several regions of the world and they are common in coastal regions and around islands. Between August 2008 and July 2009, 20 specimens of C. mydas were found dead on the beaches of Ubatuba, São Paulo, Brazil. The stomachs were removed and anthropogenic wastes were separated according their malleability and color. Of those animals, nine had ingested marine debris. Soft plastic was the most frequent among the samples and the majority of fragments was white or colorless and was between zero and five cm. Many studies have shown a high incidence of eating waste for some species of sea turtles. The record of ingestion of mostly transparent and white anthropogenic wastes in this study strengthens the hypothesis that these animals mistake them for jellyfish. Although the intake of anthropogenic waste causes impact on the lives of sea turtles, such studies are still scarce in Brazil.
显示更多 [+] 显示较少 [-]