خيارات البحث
النتائج 461 - 470 من 1,545
Assessing, managing and monitoring contaminated aquatic sediments النص الكامل
2012
Chapman, P. M. | Smith, Murray
Contaminated sediments continue to be a global problem that is too often not addressed in a logical, tiered framework. Such frameworks, when they exist, typically are restricted to assessment and prioritization and do not include possible remedies with accompanying follow-up monitoring to ensure those remedies were successful and further remedies are not necessary. A logical, tiered framework that encompasses all of the above (i.e., assessment through to post-remedy monitoring) is described. This framework was developed by the Canadian Government for use in Canada but has wider applications.
اظهر المزيد [+] اقل [-]On the biological connectivity of oil and gas platforms in the North Sea النص الكامل
2012
Thorpe, S.A.
Tests are made of the conjecture that the platforms in the North Sea are biologically connected, with organisms originating from some platforms reaching and substantially augmenting those at others so that, together, the platforms effectively form a sort of artificial reef. The M₂ tide results in a relatively rapid transfer of organisms between neighbouring platforms. Some 60% of platforms in the southern UK Sector are directly connected by tidal flows. Such connection in the northern Sector is relatively rare, about 23% of platforms being connected. Mean flows connect platforms in ‘strings’ sharing a common streamline spread by turbulent dispersion. Metrics are devised to indicate how well a particular platform is connected to others. Strings are broken when contributions to the concentration of organisms from platforms fall below detection limits. Many platforms are likely to be connected in strings in the southern UK Sector, but relatively few in the northern Sector.
اظهر المزيد [+] اقل [-]Monitoring strategies for drill cutting discharge in the vicinity of cold-water coral ecosystems النص الكامل
2012
Purser, Autun | Thomsen, Laurenz
Cold-water coral reefs represent some of the most biodiverse and biomass rich ecosystems in the marine environment. Despite this, ecosystem functioning is still poorly understood and the susceptibility of key species to anthropogenic activities and pollutants is unknown. In European waters, cold-water corals are often found in greatest abundance on the continental margin, often in regions rich in hydrocarbon reserves. In this viewpoint paper we discuss some of the current strategies employed in predicting and minimizing exposure of cold-water coral reef ecosystems on the Norwegian margin to waste materials produced during offshore drilling operations by the oil and gas industry. In the light of recent in situ and experimental research conducted with the key reef species Lophelia pertusa, we present some possible improvements to these strategies which may be utilized by industry and managers to further reduce the likelihood of exposure. We further highlight important outstanding research questions in this field.
اظهر المزيد [+] اقل [-]Assessment of perfluorinated compounds (PFCs) in plasma of bottlenose dolphins from two southeast US estuarine areas: Relationship with age, sex and geographic locations النص الكامل
2012
Fair, Patricia A. | Houde, Magali | Hulsey, Thomas C. | Bossart, Gregory D. | Adams, Jeff | Balthis, Len | Muir, Derek C.G.
Plasma PFCs were measured in 157 bottlenose dolphins (Tursiops truncatus) sampled from two US southeast Atlantic sites (Charleston (CHS), SC and Indian River Lagoon (IRL), FL) during 2003–2005. ∑PFCs, perfluoroalkyl carboxylates (∑PFCAs), perfluoroalkyl sulfonates (∑PFSAs) and individual compounds were significantly higher in CHS dolphins for all age/sex categories compared to IRL dolphins. Highest ∑PFCs concentrations occurred in CHS juvenile dolphins (2340ng/g w.w.); significantly higher than found in adults (1570ng/g w.w. males; 1330ng/g w.w. females). ∑PFCAs were much greater in CHS dolphins (∼21%) compared to IRL dolphins (∼7%); ∑PFSAs were 79% in CHS dolphins versus 93% in IRL dolphins. PFOS, the dominant compound, averaged 72% and 84%, respectively, in CHS and IRL dolphins. Decreasing PFC levels occurred with age on the bioaccumulation of PFCs in both sites. These observations suggest PFC accumulation in these two dolphin populations are influenced by site-specific exposures with significantly higher levels in CHS dolphins.
اظهر المزيد [+] اقل [-]Biofiltration of fishpond effluents and accumulation of N-compounds (phycobiliproteins and mycosporine-like amino acids) versus C-compounds (polysaccharides) in Hydropuntia cornea (Rhodophyta) النص الكامل
2012
The biofiltration capacity, biomass-yield and accumulation of N- and C-compounds of Hydropuntia cornea were analyzed. Algae were grown in different conditions for 28d: outdoor and indoor, with or without fishpond effluents. N-uptake efficiency of these effluents was higher than 95% after 7d both outdoors and indoors. N-enriched conditions reduced the extent of photoinhibition and increased the maximal quantum yield in H. cornea. The biomass-yield was higher in outdoor grown-algae after 7d and decreased independently of the treatment after 28d. N, acid polysaccharide (AP) and mycosporine-like amino acid (MAA)-yields decreased throughout the experiment in all conditions. The highest MAA-yield was observed in fishpond effluent outdoor-grown algae, indicating a positive effect of increased radiation on MAA accumulation. However, APs were higher under N-depleted conditions. The use of MAAs as UV-screening and antioxidants, and the use of AP as immunostimulants are discussed.
اظهر المزيد [+] اقل [-]Rapid increase in copper concentrations in a new marina, San Diego Bay النص الكامل
2012
Biggs, Trent W. | D’Anna, Heather
Concentrations of copper in water rose rapidly following the introduction of boats to a new marina in San Diego Bay. Two months after the marina reached half its capacity, a majority of water samples exceeded chronic and acute criteria for dissolved copper, and copper concentrations in several samples exceeded the highest concentrations observed in another marina that has been listed as an impaired water body. A box model suggested that a small fraction of the leached copper was sequestered in sediment. Copper concentrations in water entering the marina from the bay was more than half the chronic concentration limit, so only 50% of marina boat capacity could be accommodated without exceeding the chronic criterion more than 50% of the time. Copper concentrations in water may increase rapidly following boat introduction in small marinas, but could return to pre-introduction levels by controlling boat numbers or reducing use of copper-based paints.
اظهر المزيد [+] اقل [-]Setting limits for acceptable change in sediment particle size composition following marine aggregate dredging النص الكامل
2012
Cooper, Keith M.
In the UK, Government policy requires marine aggregate extraction companies to leave the seabed in a similar physical condition after the cessation of dredging. This measure is intended to promote recovery, and the return of a similar faunal community to that which existed before dredging. Whilst the policy is sensible, and in line with the principles of sustainable development, the use of the word ‘similar’ is open to interpretation. There is, therefore, a need to set quantifiable limits for acceptable change in sediment composition. Using a case study site, it is shown how such limits could be defined by the range of sediment particle size composition naturally found in association with the faunal assemblages in the wider region. Whilst the approach offers a number of advantages over the present system, further testing would be required before it could be recommended for use in the regulatory context.
اظهر المزيد [+] اقل [-]Baseline for beached marine debris on Sand Island, Midway Atoll النص الكامل
2012
Ribic, Christine A. | Sheavly, Seba B. | Klavitter, John
Baseline measurements were made of the amount and weight of beached marine debris on Sand Island, Midway Atoll, June 2008–July 2010. On 23 surveys, 32,696 total debris objects (identifiable items and pieces) were collected; total weight was 740.4kg. Seventy-two percent of the total was pieces; 91% of the pieces were made of plastic materials. Pieces were composed primarily of polyethylene and polypropylene. Identifiable items were 28% of the total; 88% of the identifiable items were in the fishing/aquaculture/shipping-related and beverage/household products-related categories. Identifiable items were lowest during April–August, while pieces were at their lowest during June–August. Sites facing the North Pacific Gyre received the most debris and proportionately more pieces. More debris tended to be found on Sand Island when the Subtropical Convergence Zone was closer to the Atoll. This information can be used for potential mitigation and to understand the impacts of large-scale events such as the 2011 Japanese tsunami.
اظهر المزيد [+] اقل [-]The occurrence and distribution of pharmaceutical compounds in the effluents of a major sewage treatment plant in Northern Taiwan and the receiving coastal waters النص الكامل
2012
Fang, Tien-Hsi | Nan, Fan-Hua | Chin, Tzong-Shean | Feng, Huimin
The pharmaceutical residues in waste water from the largest sewage treatment plant (STP) in Northern Taiwan and in seawater around the effluent discharged area were determined. An environmental risk assessment for the marine environment was conducted based on the environment risk quotient (ERQ). The concentrations of the analyzed compounds in STP influent and effluent were generally higher than those found in coastal seawater. Relatively higher values were found at the estuarine mouth and the discharged area, suggesting that the STP effluent is a point source. The removal efficiency and half life of the analyzed compounds were 6.3–46.8% and 3–18days, respectively. The ERQ value theoretical calculation was generally greater than 1. However, when the measured concentrations replaced the predicated concentrations, the ERQ values were considerably lower than 1. Therefore, our results call for a re-evaluation of the risks posed by pharmaceuticals to coastal marine ecosystems in Northern Taiwan.
اظهر المزيد [+] اقل [-]Estimates of sediment and nutrient loads in 10 major catchments draining to the Great Barrier Reef during 2006–2009 النص الكامل
2012
Joo, Marianna | Raymond, Myriam A.A. | McNeil, Vivienne H. | Huggins, Raethea | Turner, Ryan D.R. | Choy, Satish
The Great Barrier Reef (GBR) catchment area has been monitored simultaneously for sediment and nutrient exports from 10 priority catchments discharging into the GBR lagoon between 2006 and 2009. This allows GBR catchment-wide exports to be estimated and spatially compared within a discrete time-frame. Elevated levels of sediment and nutrient exports were recorded in all monitored catchments as compared to pre-European estimates, but vary around previous estimates of mean annual loads. During the period of monitoring, the Burdekin and Fitzroy catchments contributed the highest sediment and nutrient exports, however when loads were normalised for area, these catchments produced the lowest unit yields. In contrast, the highest yields were produced in the wetter and proportionately more intensively cultivated Johnstone, O’Connell, and Pioneer catchments particularly for dissolved nitrogens. This assessment offers the necessary scientific foundation for future monitoring, assessment, and management of sediment and nutrient loads entering the GBR.
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