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1.
The coral reef at Kahekili, Maui is located ~300 m south of the Lahaina Wastewater Reclamation Facility which uses four Class V injection wells to dispose of 3-5 million gallons of wastewater effluent daily. Prior research documented that the wastewater effluent percolates into the nearshore region of Kahekili. To determine if the wastewater effluent was detectable in the surface waters offshore, we used algal bioassays from the nearshore region to 100 m offshore and throughout the water column from the surface to the benthos. These algal bioassays documented that significantly more wastewater effluent was detected in the surface rather than the benthic waters and allowed us to generate a three-dimensional model of the wastewater plume in the Kahekili coastal region. Samples located over freshwater seeps had the highest δ(15)N values (~30-35‰) and the effluent was detected in surface samples 500 m south and 100 m offshore of the freshwater seeps (~8-11‰).  相似文献   
2.
The MOx instrument was developed to characterize the reactive nature of the martian soil. The objectives of MOx were: (1) to measure the rate of degradation of organics in the martian environment; (2) to determine if the reactions seen by the Viking biology experiments were caused by a soil oxidant and measure the reactivity of the soil and atmosphere: (3) to monitor the degradation, when exposed to the martian environment, of materials of potential use in future missions; and, finally, (4) to develop technologies and approaches that can be part of future soil analysis instrumentation. The basic approach taken in the MOx instrument was to place a variety of materials composed as thin films in contact with the soil and monitor the physical and chemical changes that result. The optical reflectance of the thin films was the primary sensing-mode. Thin films of organic materials, metals, and semiconductors were prepared. Laboratory simulations demonstrated the response of thin films to active oxidants.  相似文献   
3.
Biodiesel, a mixture of fatty acid methyl esters (FAMEs) derived from animal fats or vegetable oils, is rapidly moving towards the mainstream as an alternative source of energy. However, the behavior of biodiesel, or blends of biodiesel with fossil diesel, in the marine environment have yet to be fully understood. Hence, we performed a series of initial laboratory experiments and simple calculations to evaluate the microbial and environmental fate of FAMEs. Aerobic seawater microcosms spiked with biodiesel or mixtures of biodiesel and fossil diesel revealed that the FAMEs were degraded at roughly the same rate as n-alkanes, and more rapidly than other hydrocarbon components. The residues extracted from these different microcosms became indistinguishable within weeks. Preliminary results from physical-chemical calculations suggest that FAMEs in biodiesel mixtures will not affect the evaporation rates of spilled petroleum hydrocarbons but may stabilize oil droplets in the water column and thereby facilitate transport.  相似文献   
4.
We analysed the extent to which European politicians have adhered to scientific recommendations on annual total allowable catches (TACs) from 1987 to 2011, covering most of the period of the Common Fisheries Policy (CFP). For the 11 stocks examined, TACs were set higher than scientific recommendations in 68% of decisions. Politically-adjusted TACs averaged 33% above scientifically recommended levels. There was no evidence that the 2002 reform of the CFP improved decision-making, as was claimed at the time. We modelled the effects of such politically-driven decision-making on stock sustainability. Our results suggest that political adjustment of scientific recommendations dramatically increases the probability of a stock collapsing within 40 years.In 2012 European fisheries policy will undergo a once-a-decade reform. Ten years ago radical reforms were promised but the changes failed to improve sustainability. It is likely that the 2012 reform will be similarly ineffective unless decision-making is changed so that catch allocations are based on science rather than politics.  相似文献   
5.
Considerable debate surrounds the sources of oxygenated polybrominated diphenyl ethers (O-PBDEs) in wildlife as to whether they are naturally produced or result from anthropogenic industrial activities. Natural radiocarbon (14C) abundance has proven to be a powerful tool to address this problem as recently biosynthesized compounds contain contemporary (i.e. modern) amounts of atmospheric radiocarbon; whereas industrial chemicals, mostly produced from fossil fuels, contain no detectable 14C. However, few compounds isolated from organisms have been analyzed for their radiocarbon content. To provide a baseline, we analyzed the 14C content of four O-PBDEs. These compounds, 6-OH-BDE47, 2′-OH-BDE68, 2′,6-diOH-BDE159, and a recently identified compound, 2′-MeO-6-OH-BDE120, were isolated from the tropical marine sponges Dysidea granulosa and Lendenfeldia dendyi. The modern radiocarbon content of their chemical structures (i.e. diphenyl ethers, C12H22O) indicates that they are naturally produced. This adds to a growing baseline on, at least, the sources of these unusual compounds.  相似文献   
6.
To understand the spatial variation in concentrations and compositions of organic micropollutants in marine plastic debris and their sources, we analyzed plastic fragments (∼10 mm) from the open ocean and from remote and urban beaches. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), dichloro-diphenyl-trichloroethane and its metabolites (DDTs), polybrominated diphenyl ethers (PBDEs), alkylphenols and bisphenol A were detected in the fragments at concentrations from 1 to 10,000 ng/g. Concentrations showed large piece-to-piece variability. Hydrophobic organic compounds such as PCBs and PAHs were sorbed from seawater to the plastic fragments. PCBs are most probably derived from legacy pollution. PAHs showed a petrogenic signature, suggesting the sorption of PAHs from oil slicks. Nonylphenol, bisphenol A, and PBDEs came mainly from additives and were detected at high concentrations in some fragments both from remote and urban beaches and the open ocean.  相似文献   
7.
We considered small-scale measurement of permeability in pebbly sands having coarser grains supported in a finer grained matrix (fine packing). Our central question was whether air-based measurements are representative if made with a permeameter tip seal pressed in the sand matrix. We created pebbly sands and variably sorted sands, with systematic variation in aspects of their fine packing. We made permeability measurements by inserting the tip seal of an air permeameter in the matrix of these samples and compared them to the permeability of the composite sample determined by both water-based methods and theory. The air-permeameter measurements made in this way represent the permeability of the composite mixtures of coarser and finer grains and allow for the discernment of permeability between samples with different matrix compositions, ranging from fine to coarse sand. Furthermore, the collective results show that permeability differences in the pebbly sands and variably sorted sands with fine packing, however measured, are primarily due to differences in matrix permeability and not due to differences in the size or the percentage of the coarser grains.  相似文献   
8.
To better constrain sampling strategies for observing biologically sensitive parameters in ground water, we vigorously pumped for 120 h a lightly pumped well completed in a confined glacial aquifer while observing how various physical and chemical parameters evolve in the water produced. The parameters commonly monitored when sampling a well stabilized within about an hour, after 5 wellbore volumes were produced; these parameters include temperature, pH, dissolved oxygen, oxidation-reduction potential (Eh), and electrical conductivity. The concentrations of ferrous iron, sulfide, and sulfate and various biological or biologically sensitive parameters, including the concentrations of dissolved hydrogen and methane, direct cell counts, and the microbial community profile, in contrast, required more than 8 h or 36 well volumes to stabilize. We interpret this result to mean that the zone of influence of the wellbore on biologic processes in the aquifer extends beyond the commonly recognized zone where physical properties are affected. A second period of adjustment of these biologically sensitive parameters began after about 50 h of pumping, following displacement of 230 wellbore volumes, and continued to the end of the experiment. During this period, the cell density and the composition of the microbial community suspended in the water samples changed. This finding indicates that the microbial community in and near the wellbore changed in response to pumping and the changes affected aspects of the composition of water produced from the well. The study demonstrates the importance of allowing adequate pumping time when sampling ground water for the analysis of biologically sensitive parameters.  相似文献   
9.
An assessment of the effects of the 'Prestige' oil spill on intertidal, macroalgal assemblages was carried out comparing abundance data obtained before and after the spill. Four zones in the North and Northwest coast of Spain were sampled, one of them located at the immediate vicinity of the spill, the zone most heavily oiled. Macroalgal assemblages had similar structure between years. Neither critical decrease in abundance of the dominant macroalgae, nor increase in opportunistic species were found. Some differences in abundance were observed, but they did not show any pattern, being more likely the result of the natural variability of the assemblage. Extensive, but not intense fuel deposition on the shores and a limited use of aggressive cleanup methods are suggested as possible causes for the lack of the effects in these assemblages after the 'Prestige' oil spill.  相似文献   
10.
Plastic ingestion by planktivorous fishes in the North Pacific Central Gyre   总被引:2,自引:0,他引:2  
A significant amount of marine debris has accumulated in the North Pacific Central Gyre (NPCG). The effects on larger marine organisms have been documented through cases of entanglement and ingestion; however, little is known about the effects on lower trophic level marine organisms. This study is the first to document ingestion and quantify the amount of plastic found in the gut of common planktivorous fish in the NPCG. From February 11 to 14, 2008, 11 neuston samples were collected by manta trawl in the NPCG. Plastic from each trawl and fish stomach was counted and weighed and categorized by type, size class and color. Approximately 35% of the fish studied had ingested plastic, averaging 2.1 pieces per fish. Additional studies are needed to determine the residence time of ingested plastics and their effects on fish health and the food chain implications.  相似文献   
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