خيارات البحث
النتائج 1671 - 1680 من 4,042
Managing Groundwater Nitrate Contamination from Livestock Farms: Implication for Nitrate Management Guidelines النص الكامل
2016
Sahoo, Prafulla Kumar | Kim, Kangjoo | Powell, M. A.
Significant nitrate contamination of groundwater has been observed in various parts of the world; intensive livestock farming is one of the major causes. This paper reviews various guidelines/regulations, which have been developed in advanced countries such as USA, Canada, Australia, and Europe to combat this problem by designing effective monitoring and management programs. Monitoring programs deal mainly with selection of sites, number of monitoring wells, specific parameters, and sampling frequency, which are helpful for identifying the source and extend of the contamination. Management programs deal with selection of suitable location, site characterization, proximity of livestock facilities and drinking wells, and proper storage, maintenance of the facilities, and limits of manures application in order to minimize nitrate leaching into groundwater. The main aim of this paper is to help states/countries, which do not have any guideline, and consulting engineers/consultants/owners of livestock operation in the design of effective strategies for point source nitrate management.
اظهر المزيد [+] اقل [-]Spatial distribution and seasonal variation of the trace hazardous element contamination in Jakarta Bay, Indonesia النص الكامل
2016
Siregar, Tuti Hartati | Priyanto, Nandang | Putri, Ajeng Kurniasari | Rachmawati, Novalia | Triwibowo, Radestya | Dsikowitzky, Larissa | Schwarzbauer, Jan
The Jakarta Bay Ecosystem is located in the vicinity of the megacity Jakarta, the capital city of Indonesia. Surrounding rivers and canals, carrying solid and fluid waste from households and several industrial areas, flow into the bay. Therefore, the levels of selected trace hazardous elements in water, surface sediments and animal tissues were determined. Samples were collected from two different seasons. The spatial distribution pattern of trace elements in sediment and water as well as the seasonal variation of the contamination were assessed. Quality assessment of sediment using the effects range median (ERM) showed that the concentrations of Hg, Cu and Cr at some stations exceeded the recommended values. Moreover, the concentrations of several trace hazardous elements in the sediments exceeded previously reported toxicity thresholds for benthic species.
اظهر المزيد [+] اقل [-]Current status of coral reefs in the United Arab Emirates: Distribution, extent, and community structure with implications for management النص الكامل
2016
Grizzle, Raymond E. | Ward, Krystin M. | AlShihi, Rashid M.S. | Burt, John A.
Coral reefs of the United Arab Emirates were once extensive, but have declined dramatically in recent decades. Marine management and policy have been hampered by outdated and inaccurate habitat maps and habitat quality information. We combined existing recent datasets with our newly mapped coral habitats to provide a current assessment of nation-wide extent, and performed quantitative surveys of communities at 23 sites to assess coral cover and composition. Over 132km2 of coral habitat was mapped, averaging 28.6±3.8% live coral cover at surveyed sites. In the Arabian Gulf low cover, low richness Porites dominated communities characterized western Abu Dhabi, while reefs northeast of Abu Dhabi city generally contained higher richness and cover, and were dominated by merulinids (formerly faviids). Distinct communities occur in the Sea of Oman, where cover and richness were low. We provide management recommendations to enhance conservation of vulnerable coral reefs in the UAE.
اظهر المزيد [+] اقل [-]On the possibility to produce again oysters Crassostrea gigas in the North Médoc salt marshes (Gironde estuary, Southwestern France): A comparison study of metals bioaccumulation in spats 13years after النص الكامل
2016
Baudrimont, Magalie | Chelini, Audrey | Gourves, Pierre-Yves | Maury-Brachet, Régine | Legeay, Alexia
The Gironde Estuary is known for its historic poly-metallic contamination, leading to levels of Cd in oysters Crassostrea gigas above the human consumption limit. However, since 25years, Cd concentrations progressively decreased in the estuary and the question is raised if the same evolution occurred in the North Médoc salt marshes. In this aim, we analyzed 12 metals in juveniles of oysters transplanted from a hatchery on a 12months period in 2 salt marshes. Moreover, the comparison of four metals already measured 13years ago was conducted.The major results showed an overall decrease of the metals in the salt marshes, with a significant decrease of Cd reaching 80% compared to the Gironde estuary where it occurs for only 50% between 2001 and 2014. The concentrations in 2014 remained below the human consumption threshold, suggesting the possibility to produce again oysters in the salt marshes.
اظهر المزيد [+] اقل [-]Weathering of field-collected floating and stranded Macondo oils during and shortly after the Deepwater Horizon oil spill النص الكامل
2016
Stout, Scott A. | Payne, James R. | Emsbo-Mattingly, Stephen D. | Baker, Gregory
Chemical analysis of large populations of floating (n=62) and stranded (n=1174) Macondo oils collected from the northern Gulf of Mexico sea surface and shorelines during or within seven weeks of the end of the Deepwater Horizon oil spill demonstrates the range, rates, and processes affecting surface oil weathering. Oil collected immediately upon reaching the sea surface had already lost most mass below n-C8 from dissolution of soluble aliphatics, monoaromatics, and naphthalenes during the oil's ascent with further reductions extending up to n-C13 due to the onset of evaporation. With additional time, weathering of the floating and stranded oils advanced with total PAH (TPAH50) depletions averaging 69±23% for floating oils and 94±3% for stranded oils caused by the combined effects of evaporation, dissolution, and photo-oxidation, the latter of which also reduced triaromatic steroid biomarkers. Biodegradation was not evident among the coalesced floating oils studied, but had commenced in some stranded oils.
اظهر المزيد [+] اقل [-]Assessment of the fitness of the mussel Mytilus galloprovincialis two years after the Hebei Spirit oil spill النص الكامل
2016
Donaghy, Ludovic | Hong, Hyun-Ki | Kim, Moonkoo | Park, Heung-Sik | Choi, Kwang-Sik
In December 2007, >150km of the West coast of Korea were heavily polluted by crude oil leaked from the oil tanker Hebei Spirit, leading to mass mortality of bivalve mollusks on the intertidal areas. Two years after, mussels Mytilus galloprovincialis were collected from two impacted sites to investigate sub-lethal effects of the oil spill. Tissue content in polycyclic aromatic hydrocarbons (PAHs), hemocyte parameters, reproductive status and energetic reserves were analyzed. PAHs in tissues of mussels as well as hemocyte parameters were not different between impacted and control sites. Energetic reserves were altered in mussels from the impacted sites. Glycogen content remained low at polluted sites, whatever the season. Two years after the Hebei Spirit oil spill, mussels then presented altered energetic metabolism. Further investigations are thus warranted to monitor the sustainability of mussel populations on the oil spilled West coast of Korea.
اظهر المزيد [+] اقل [-]Mangrove propagule size and oil contamination effects: Does size matter? النص الكامل
2016
Naidoo, Gonasageran
Three mangroves species with differential propagule size, Avicennia marina (2.5±0.3cm), Bruguiera gymnorrhiza (16±2cm) and Rhizophora mucronata (36±3cm), were subjected to oil contamination. In a series of glasshouse and field experiments, the sediment, propagules, leaves and stems were oiled and growth monitored. Oiling of the propagules, leaves, internodes or sediment reduced plant height, leaf number, leaf chlorophyll content index and induced growth abnormalities, leaf abscission and mortality, with effects being greatest in A. marina, intermediate in R. mucronata and least in B. gymnorrhiza. The results suggest that the greater susceptibility of A. marina to oil is due to early shedding of the protective pericarp and rapid root and shoot development after detachment from the parent tree and not to propagule size. After seedling emergence, micromorphological factors such as presence of trichomes, salt glands and thickness of protective barriers influence oil tolerance.
اظهر المزيد [+] اقل [-]Date-prints on stranded macroplastics: Inferring the timing and extent of overwash deposition on the Skallingen peninsula, Denmark النص الكامل
2016
Sander, Lasse
Date-prints on stranded macroplastics: Inferring the timing and extent of overwash deposition on the Skallingen peninsula, Denmark النص الكامل
2016
Sander, Lasse
The presented study shows that the delivery of marine macrodebris to a high-energy coastal environment has been abundant enough over the last three decades as to allow a spatial reconstruction of morphological change based on production-date prints. A dataset of >110 spatially discrete samples has been collected in an area affected by overwashing on the Skallingen peninsula, SW Denmark. A conceptual model for the chronological interpretation of the date prints is proposed and cross-compared with a dense time-series of satellite images and orthophotos. It appears that the litter-derived ages are capable of reproducing information on both the timing and the extent of overwash occurrence. Despite the usefulness of the method as a tool for rapidly assessing the approximate age of recent coastal deposits, the study shows the alarming degree and long-standing of marine-litter pollution on the eastern board of the southern North Sea.
اظهر المزيد [+] اقل [-]Date-prints on stranded macroplastics: Inferring the timing and extent of overwash deposition on the Skallingen peninsula, Denmark النص الكامل
2016
Sander, Lasse
The presented study shows that the delivery of marine macrodebris to a high-energy coastal environment has been abundant enough over the last three decades as to allow a spatial reconstruction of morphological change based on production-date prints. A dataset of > 110 spatially discrete samples has been collected in an area affected by overwashing on the Skallingen peninsula, SW Denmark. A conceptual model for the chronological interpretation of the date prints is proposed and cross-compared with a dense time-series of satellite images and orthophotos. It appears that the litter-derived ages are capable of reproducing information on both the timing and the extent of overwash occurrence. Despite the usefulness of the method as a tool for rapidly assessing the approximate age of recent coastal deposits, the study shows the alarming degree and long-standing of marine-litter pollution on the eastern board of the southern North Sea.
اظهر المزيد [+] اقل [-]Ecotoxicological assessment of diamondback terrapin (Malaclemys terrapin) pond habitat, prey and eggs in Bermuda النص الكامل
2016
Outerbridge, Mark E. | O'Riordan, Ruth | Fort, Douglas J. | Davenport, John
Total petroleum hydrocarbons, PAH and various trace metal residues were extracted and analyzed from fresh whole diamondback terrapin (Malaclemys terrapin) eggs, whole brackish-water gastropods (terrapin prey) and benthic sediment from anchialine pond environments in Bermuda inhabited by terrapins. Gastropods and terrapin eggs showed higher concentrations of trace metals and organic contaminants than sediments. Conversely, PAHs were mostly found within the sediment and smaller amounts detected in gastropods and terrapin eggs. Results indicated that contaminants in prey were transferred to terrapin eggs, and that concentrations of several contaminants exceeded potentially toxic concentrations for aquatic vertebrates. Necropsy of unhatched eggs from nests that had yielded viable hatchlings showed significantly compromised embryonic development. Bermudian diamondback terrapins reside and feed in brackish wetland habitats characterized by widespread, multifactorial contamination. This study suggests that environmental contamination plays a role in the recorded low hatching success in terrapin eggs in Bermuda.
اظهر المزيد [+] اقل [-]Communication masking in marine mammals: A review and research strategy النص الكامل
2016
Erbe, Christine | Reichmuth, Colleen | Cunningham, Kane | Lucke, Klaus | Dooling, Robert
Underwater noise, whether of natural or anthropogenic origin, has the ability to interfere with the way in which marine mammals receive acoustic signals (i.e., for communication, social interaction, foraging, navigation, etc.). This phenomenon, termed auditory masking, has been well studied in humans and terrestrial vertebrates (in particular birds), but less so in marine mammals. Anthropogenic underwater noise seems to be increasing in parts of the world's oceans and concerns about associated bioacoustic effects, including masking, are growing. In this article, we review our understanding of masking in marine mammals, summarise data on marine mammal hearing as they relate to masking (including audiograms, critical ratios, critical bandwidths, and auditory integration times), discuss masking release processes of receivers (including comodulation masking release and spatial release from masking) and anti-masking strategies of signalers (e.g. Lombard effect), and set a research framework for improved assessment of potential masking in marine mammals.
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