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Sorption of perfluorooctane sulfonate (PFOS) on marine sediments Texto completo
2012
Chen, Hong | Zhang, Can | Yu, Yixuan | Han, Jianbo
Sorption of anionic perfluorooctane sulfonate (PFOS) on marine sediment was investigated in detail. It was found that solution ionic composition and sediment-specific parameters played important roles in affecting the sorption of PFOS. The results indicated that sorption of PFOS in seawater to marine sediments was strong (∼10 times higher than that in freshwater) and nonlinear (Freundlich nF values of 0.77–0.96). The sorption affinity was well correlated with sediment organic carbon content, indicating the importance of hydrophobic interactions. At a PFOS aqueous concentration of 10μg/L, PFOS distribution coefficients increased with the increasing salinity in solution, with an average rate of 0.48±0.03log units per a log unit of salinity. Further studies demonstrated that among common ions contributing to the salinity in seawater, dissolved calcium and magnesium are dominantly responsible for the sorption-enhancing effect of salinity for PFOS. This work will aid in better understanding of PFOS sorption mechanisms, and be useful for fate modeling of this class of contaminants in the marine environment.
Mostrar más [+] Menos [-]A bioindicator system for water quality on inshore coral reefs of the Great Barrier Reef Texto completo
2012
Fabricius, Katharina E. | Cooper, Timothy F. | Humphrey, Craig | Uthicke, Sven | De’ath, Glenn | Davidson, Johnston | LeGrand, Hélène | Thompson, Angus | Schaffelke, Britta
Responses of bioindicator candidates for water quality were quantified in two studies on inshore coral reefs of the Great Barrier Reef (GBR). In Study 1, 33 of the 38 investigated candidate indicators (including coral physiology, benthos composition, coral recruitment, macrobioeroder densities and FORAM index) showed significant relationships with a composite index of 13 water quality variables. These relationships were confirmed in Study 2 along four other water quality gradients (turbidity and chlorophyll). Changes in water quality led to multi-faceted shifts from phototrophic to heterotrophic benthic communities, and from diverse coral dominated communities to low-diversity communities dominated by macroalgae. Turbidity was the best predictor of biota; hence turbidity measurements remain essential to directly monitor water quality on the GBR, potentially complemented by our final calibrated 12 bioindicators. In combination, this bioindicator system may be used to assess changes in water quality, especially where direct water quality data are unavailable.
Mostrar más [+] Menos [-]Inter-annual variability of wet season freshwater plume extent into the Great Barrier Reef lagoon based on satellite coastal ocean colour observations Texto completo
2012
Schroeder, Thomas | Devlin, Michelle J. | Brando, Vittorio E. | Dekker, Arnold G. | Brodie, J. E. (Jon E.) | Clementson, Lesley A. | McKinna, Lachlan
Riverine freshwater plumes are the major transport mechanism for nutrients, sediments and pollutants into the Great Barrier Reef (GBR) lagoon and connect the land with the receiving coastal and marine waters. Knowledge of the variability of the freshwater extent into the GBR lagoon is relevant for marine park management to develop strategies for improving ecosystem health and risk assessments. In this study, freshwater extent has been estimated for the entire GBR lagoon area from daily satellite observations of the Moderate Resolution Imaging Spectroradiometer (MODIS) between 2002 and 2010. To enable a reliable mapping of freshwater plumes we applied a physics-based coastal ocean colour algorithm, that simultaneously retrieves chlorophyll-a, non-algal particulate matter and coloured dissolved organic matter (CDOM), from which we used CDOM as a surrogate for salinity (S) for mapping the freshwater extent.
Mostrar más [+] Menos [-]Field studies using fish biomarkers – How many fish are enough? Texto completo
2012
Gagnon, M.M. | Hodson, P.V.
Significant efforts are invested in field studies using fish, and it is important to optimize the number of organisms collected to evaluate the possible impacts of contamination. This paper provides ecotoxicologists with the approximate numbers of fish needed to identify statistically significant differences among samples using physiological indices and biochemical markers of fish health. The numbers of fish to collect are reported for ethoxyresorufin-o-deethylase (EROD); ethoxycoumarin-o-deethylase (ECOD), serum sorbitol dehydrogenase (sSDH), stress proteins, gonadosomatic index, liver somatic index, condition factor, and biliary metabolites of polycyclic aromatic hydrocarbons. The number of fish to collect was as few as four for ECOD activity (with a power of 80%), but as high as 106 for CF (with a power of 95%). Achieving statistical significance between sites does not help in the interpretation of the biological significance of a parameter, but well-planned field samplings will maximize the chances of correctly identifying areas of concern.
Mostrar más [+] Menos [-]Spatial and temporal dynamics of size-structured photosynthetic parameters (PAM) and primary production (¹³C) of pico- and nano-phytoplankton in an atoll lagoon Texto completo
2012
Lefebvre, Sébastien | Claquin, Pascal | Orvain, Francis | Véron, Benoît | Charpy, Loïc
Atoll lagoons display a high diversity of trophic states due mainly to their specific geomorphology, and probably to their level and mode of human exploitation. We investigated the functioning of the Ahe atoll lagoon, utilized for pearl oyster farming, through estimations of photosynthetic parameters (pulse amplitude modulation fluorometry) and primary production (¹³C incorporation) measurements of the size structured phytoplankton biomass (<2μm and >2μm). Spatial and temporal scales of variability were surveyed during four seasons, over 16months, at four sites within the lagoon. While primary production (P) was dominated by the picophytoplankton, its biomass specific primary productivity (Pᴮ) was lower than in other atoll lagoons. The variables size fraction of the phytoplankton, water temperature, season, the interaction term station*fraction and site, explained significantly the variance of the data set using redundancy analysis. No significant trends over depth were observed in the range of 0–20m. A clear spatial pattern was found which was persistent over the seasons: south and north sites were different from the two central stations for most of the measured variables. This pattern could possibly be explained by the existence of water cells showing different water residence time within the lagoon. Photoacclimation strategies of the two size fractions differed through their light saturation coefficient (higher for picophytoplankton), but not through their maximum photosynthetic capacity (ETRₘₐₓ). Positive linear relationships between photosynthetic parameters indicated that their dynamic was independent of light availability in this ecosystem, but most probably dependent on nutrient availability and/or rapid changes in the community structure. Spatial and temporal patterns of the measured processes are then further discussed in the context of nutrient availability and the possible role of cultured oysters in nutrient recycling.
Mostrar más [+] Menos [-]Impacts of human activities on coral reef ecosystems of southern Taiwan: A long-term study Texto completo
2012
Liu, Pi-Jen | Meng, Pei-Jie | Liu, Li-Lian | Wang, Jih-Terng | Leu, Ming-Yih
In July 2001, the National Museum of Marine Biology and Aquarium, co-sponsored by the Kenting National Park Headquarters and Taiwan’s National Science Council, launched a Long-Term Ecological Research (LTER) program to monitor anthropogenic impacts on the ecosystems of southern Taiwan, specifically the coral reefs of Kenting National Park (KNP), which are facing an increasing amount of anthropogenic pressure. We found that the seawater of the reef flats along Nanwan Bay, Taiwan’s southernmost embayment, was polluted by sewage discharge at certain monitoring stations. Furthermore, the consequently higher nutrient and suspended sediment levels had led to algal blooms and sediment smothering of shallow water corals at some sampling sites. Finally, our results show that, in addition to this influx of anthropogenically-derived sewage, increasing tourist numbers are correlated with decreasing shallow water coral cover, highlighting the urgency of a more proactive management plan for KNP’s coral reefs.
Mostrar más [+] Menos [-]Towards ecologically relevant targets for river pollutant loads to the Great Barrier Reef Texto completo
2012
Kroon, F. J. (Frederieke J.)
Degradation of coastal ecosystems in the Great Barrier Reef (GBR), Australia, has been linked with a decline in water quality from land-based runoff. This paper examines the reduction in current end-of-catchment loads required for total suspended solids (TSS) and dissolved inorganic nitrogen (DIN) to achieve GBR water quality guidelines. Based on first-order estimates of sustainable pollutant loads, current TSS and DIN loads would need to be reduced by approximately 7000ktons/y (41%) and 6000tons/y (38%), respectively. Next, these estimated reductions for TSS and DIN are compared with Reef Plan targets for anthropogenic sediment (−20% by 2020) and nitrogen (−50% by 2013) loads. If successful, these targets will accomplish approximately 40% of TSS and 92% of DIN load reductions required to achieve sustainable loads to the GBR lagoon. These first-order estimates elucidate the need to establish ecologically relevant targets for river pollutant loads to the GBR for management and policy.
Mostrar más [+] Menos [-]Assessing, managing and monitoring contaminated aquatic sediments Texto completo
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.
Mostrar más [+] Menos [-]On the biological connectivity of oil and gas platforms in the North Sea Texto completo
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.
Mostrar más [+] Menos [-]Monitoring strategies for drill cutting discharge in the vicinity of cold-water coral ecosystems Texto completo
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.
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