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Результаты 511-520 из 1,953
Baseline metals pollution profile of tropical estuaries and coastal waters of the Straits of Malacca
2013
Looi, Ley Juen | Ahmad Zaharin Aris, | Wan Johari, Wan Lutfi | Md. Yusoff, Fatimah | Hashim, Zailina
The status report on metal pollution in tropical estuaries and coastal waters is important to understand potential environmental health hazards. Detailed baseline measurements were made on physicochemical parameters (pH, temperature, redox potential, electrical conductivity, salinity, dissolved oxygen, total dissolved solid), major ions (Na, Ca, Mg, K, HCO3, Cl, SO4 and NO3) and metals concentrations (27Al, 75As, 138Ba, 9Be, 111Cd, 59Co, 63Cu, 52Cr, 57Fe, 55Mn, 60Ni, 208Pb, 80Se, 66Zn) at estuaries and coastal waters along the Straits of Malacca. Principal component analysis (PCA) was employed to reveal potential pollution sources. Seven principal components were extracted with relation to pollution contribution from minerals-related parameters, natural and anthropogenic sources. The output from this study will generate a profound understanding on the metal pollution status and pollution risk of the estuaries and coastal system.
Показать больше [+] Меньше [-]Antifouling biocides in water and sediments from California marinas
2013
Sapozhnikova, Yelena | Wirth, Edward | Schiff, Kenneth | Fulton, Michael
Irgarol 1051 is a common antifouling biocide and is highly toxic to non-target plant species at low ng/L concentrations. We measured up to 254ng/L Irgarol in water and up to 9ng/g dry weight Irgarol in sediments from Southern California recreational marinas. Irgarol’s metabolite, M1, concentrations were up to 62ng/L in water and 5ng/g dry weight in sediments. Another antifouling biocide, diuron, reached up to 68ng/L in water and 4ng/g dry weight in sediments. The maximum Irgarol concentrations in water were greater than the Irgarol concentration recommended as the plant toxicity benchmark (136ng/L), suggesting that Irgarol concentrations may be high enough to cause changes in phytoplankton communities in the sampled marinas. Irgarol concentrations measured in sediments were greater than calculated Environmental Risk Limits (ERLs) for Irgarol in sediments (1.4ng/g). Antifouling pesticide accumulation in sediments may present a potential undetermined risk for benthic organisms.
Показать больше [+] Меньше [-]Benthic foraminiferal assemblages and trace metals reveal the environment outside the Pearl River Estuary
2013
Li, Tao | Xiang, Rong | Li, Tuanjie
We investigated the distribution patterns of the benthic foraminiferal assemblages outside the Pearl River Estuary in relation to trace metals, organic carbon and sedimentary particle fractions. The study area is unpolluted to moderately polluted by Cr, Cu, Pb and Zn and is completely polluted by Ni. The highest levels are found in the western coastal zone. Spatial distributions of the measured elements are strongly related to the behavior of the sedimentary clay fraction. The analyses of species abundance and community diversity as well as subsequent canonical correspondence analysis were used to reveal the relationship between foraminifera data and environmental parameters. Four sampling site groups established by factor analysis were distributed from the coastal area to the inner shelf. Their distribution patterns have a strong correlation with Cu, Pb and Ba. This research shows that benthic foraminifera can be used as bioindicators of trace metal pollutants outside the Pearl River Estuary.
Показать больше [+] Меньше [-]Biogeochemical characterization of MC252 oil:sand aggregates on a coastal headland beach
2013
Urbano, Marilany | Elango, Vijaikrishnah | Pardue, John H.
MC252 oil:sand aggregates, termed surface residue balls (SRBs), were sampled for physical, chemical and microbial characteristics from different tidal zones on a coastal headland beach in Louisiana, USA. Supratidal SRBs were smaller, had low moisture content, and salinities that were <2ppt. Intertidal SRBs were hypersaline and had higher N and sulfate concentrations, consistent with regular tidal inundation. Crude oil components were highest in the intertidal “oil mat” SRBs with C1- and C2-phenanthrenes, C2- and C3-dibenzothiophenes comprising the majority of the PAH concentrations. In the other SRB categories, PAHs and alkanes were depleted and profiles were skewed toward higher molecular weight compounds. Oxygen microelectrode measurements demonstrated that saturated O2 is present immediately after wetting, but O2 consumption in the interior of the aggregate occurs after a few days. Microbial populations varied with position on the beach but sequences similar to known PAH-degrading taxa (Mycobacterium sp. and Stenotrophomonas sp.) were observed.
Показать больше [+] Меньше [-]Ingestion of plastic marine debris by Common and Thick-billed Murres in the northwestern Atlantic from 1985 to 2012
2013
Bond, Alexander L. | Provencher, Jennifer F. | Elliot, Richard D. | Ryan, Pierre C. | Rowe, Sherrylynn | Jones, Ian L. | Robertson, Gregory J. | Wilhelm, Sabina I.
Plastic ingestion by seabirds is a growing conservation issue, but there are few time series of plastic ingestion with large sample sizes for which one can assess temporal trends. Common and Thick-billed Murres (Uria aalge and U. lomvia) are pursuit-diving auks that are legally harvested in Newfoundland and Labrador, Canada. Here, we combined previously unpublished data on plastic ingestion (from the 1980s to the 1990s) with contemporary samples (2011–2012) to evaluate changes in murres’ plastic ingestion. Approximately 7% of murres had ingested plastic, with no significant change in the frequency of ingestion among species or periods. The number of pieces of plastic/bird, and mass of plastic/bird were highest in the 1980s, lowest in the late 1990s, and intermediate in contemporary samples. Studying plastic ingestion in harvested seabird populations links harvesters to conservation and health-related issues and is a useful source of large samples for diet and plastic ingestion studies.
Показать больше [+] Меньше [-]Dominance patterns in macroalgal and phytoplankton biomass under different nutrient loads in subtropical coastal lagoons of the SE Gulf of California
2013
Páez-Osuna, F. | Piñón-Gimate, A. | Ochoa-Izaguirre, M.J. | Ruiz-Fernández, A.C. | Ramírez-Reséndiz, G. | Alonso-Rodríguez, R.
Nine macroalgal blooms were studied in five coastal lagoons of the SE Gulf of California. The nutrient loads from point and diffuse sources were estimated in the proximity of the macroalgal blooms. Chlorophyll a and macroalgal biomass were measured during the dry, rainy and cold seasons. Shrimp farms were the main point source of nitrogen and phosphorus loads for the lagoons. High biomasses were found during the dry season for phytoplankton at site 6 (791.7±34.6mgm−2) and during the rainy season for macroalgae at site 4 (296.0±82.4gm−2). Depending on the season, the phytoplankton biomass ranged between 40.0 and 791.7mgm−2 and the macroalgal biomass between 1 and 296.0gm−2. The bulk biomass (phytoplankton+macroalgal) displayed the same tendency as the nutrient loads entering the coastal lagoons. Phytoplankton and macroalgal biomass presented a significant correlation with the atomic N:P ratio.
Показать больше [+] Меньше [-]Spatial distribution and historical input of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in sediments from a subtropical estuary (Guaratuba Bay, SW Atlantic)
2013
Combi, Tatiane | Taniguchi, Satie | Figueira, Rubens Cesar Lopes | Mahiques, Michel Michaelovitch de | Martins, César C.
This study evaluated the occurrence and distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in 22 surface sediment samples and one core collected in Guaratuba Bay, a large and well-preserved estuary in Southern Atlantic, Brazil. The concentration of PCBs in the superficial sediment samples ranged from <LQ (below the limit of quantification) to 5.62ngg−1, while the concentration of OCPs ranged from <LQ to 0.74ngg−1. The spatial distribution of the organochlorine compounds (OCs) suggested that the sources of these contaminants are located outside the bay and are related to human activities on the margins of the two main rivers that discharge in the region. The OCs in the sediment core ranged from <LQ to 0.52ngg−1 and from <LQ to 1.52ngg−1 for PCBs and OCPs, respectively. Despite their usage worldwide, the low concentrations of OCs in Guaratuba Bay suggest low input levels, which may represent the background levels for this region.
Показать больше [+] Меньше [-]Coupled hydrodynamic and wastewater plume models of Belfast Lough, Northern Ireland: A predictive tool for future ecological studies
2013
Pritchard, Daniel | Savidge, Graham | Elsäßer, Björn
Wastewater outfalls provide a natural laboratory for the study of nutrient dynamics in coastal seas, however if properly designed and operated their impact can be difficult to detect. A model was developed and applied to investigate the effect of variation in hydrodynamic conditions on the transport and dilution of a treated wastewater plume in Belfast Lough, Northern Ireland. To validate these predictions we measured the physiochemical properties of the waters surrounding the outfall with a specific focus on inherent plume tracers likely to be relevant to the study of macroalgae (salinity, nitrogen and phosphorus). The model performed well and our data show high dilution of the plume, even under neap-tide conditions. This provides a spatially and temporally defined predictive framework for future studies investigating the compliance of Northern Ireland’s coastal waters with European Water Framework Directive objectives and for feasibility studies investigating macroalgal aquaculture near wastewater outfalls.
Показать больше [+] Меньше [-]Kinetics of the PO4-P adsorption onto soils and sediments from the Mondego estuary (Portugal)
2013
Otero, M. | Coelho, J.P. | Rodrigues, E.T. | Pardal, M.A. | Santos, E.B.H. | Esteves, V.I. | Lillebø, A.I.
In order to assess the status of a North Atlantic Ocean Ecoregion (Mondego system, Portugal) after the implementation of a management programme, a study on PO4-P sorption was carried out. Considering that sorption velocity markedly determines the systems promptness to phosphorus external loading, the kinetics of the sorption of PO4-P onto estuarine sediments and the upstream agricultural soils was studied. The pseudo-second order kinetic equation gave an appropriate description of PO4-P sorption onto these soils and sediments, allowing for a quantitative comparison. For soils, the kinetic constants (k2⁎, μg−1gh−1) ranged between 0.007 and 0.017μg−1gh−1 while, in the case of sediments these ranged between 0.008 and 0.012μg−1gh−1. Results showed that the reduction of water residence time after the management action was relevant for the system status, affecting its reaction capacity to phosphorus loading.
Показать больше [+] Меньше [-]Effects of fish farming on phytoplankton community under the thermal stress caused by a power plant in a eutrophic, semi-enclosed bay: Induce toxic dinoflagellate (Prorocentrum minimum) blooms in cold seasons
2013
Jiang, Zhibing | Liao, Yibo | Liu, Jingjing | Shou, Lu | Chen, Quanzhen | Yan, Xiaojun | Zhu, Genhai | Zeng, Jiangning
Six cruises were conducted in a fish farm adjacent to the Ninghai Power Plant in Xiangshan Bay, East China Sea. Fish farming significantly increased NH4+, DIP, and TOC concentrations, while it significantly decreased the DO level. These increase/decrease trends were more pronounced in warmer seasons. Although culture practices did not significantly increase phytoplankton density, it drastically enhanced dinoflagellate abundance and domination. Significant differences in species diversity and community composition between the cages and the control area were also observed. Temperature elevation caused by thermal discharge associated with eutrophication resulted in a dominant species shift from diatoms alone to dinoflagellates and diatoms. This is the first report of stress-induced toxic dinoflagellate (Prorocentrum minimum) blooms in winter and the winter–spring transition in this bay. Therefore, the effects of aquaculture activity and power plant construction in such a eutrophic, semi-enclosed bay require further attention.
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