Refinar búsqueda
Resultados 981-990 de 2,512
Characterization of fish hold effluent discharged from commercial fishing vessels into harbor waters Texto completo
2014
Albert, Ryan J. | McLaughlin, Christine | Falatko, Debra
Fish hold effluent and the effluent produced from the cleaning of fish holds may contain organic material resulting from the degradation of seafood and cleaning products (e.g., soaps and detergents). This effluent is often discharged by vessels into near shore waters and, therefore, could have the potential to contribute to water pollution in bays and estuaries. We characterized effluent from commercial fishing vessels with holds containing refrigerated seawater, ice slurry, or chipped ice. Concentrations of trace heavy metals, wet chemistry parameters, and nutrients in effluent were compared to screening benchmarks to determine if there is a reasonable potential for effluent discharge to contribute to nonattainment of water quality standards. Most analytes (67%) exceeded their benchmark concentration and, therefore, may have the potential to pose risk to human health or the environment if discharges are in significant quantities or there are many vessels discharging in the same areas.
Mostrar más [+] Menos [-]Deepwater marine litter densities and composition from submersible video-transects around the ABC-islands, Dutch Caribbean Texto completo
2014
Debrot, A.O. | Vinke, E. | van der Wende, G. | Hylkema, A. | Reed, J.K.
Baseline data on anthropogenic seafloor debris contamination in the year 2000 is provided for 24 submersible video transects at depths of 80–900m, off the Dutch ABC-islands (Aruba, Bonaire, Curaçao), in the southeastern Caribbean Sea. In total, 202 objects were documented from a combined 21,184m of transect, ranging from sandy lower island-slope to rocky upper island-slope habitat. Debris densities differed significantly with depth. Highest debris accumulation (0.459 items 100m−2 or 4590 items per km2) occurred at depths of 300–600m on more shallow-sloping (20–30°) sand and silt bottoms. The overall average debris density was 0.27 objects per 100m2 (or 2700 items per km2), which is an order of magnitude higher than most other deepwater debris studies. What we describe may be representative for other small, populated, steep volcanic Caribbean islands. Food and beverage-related items were the single largest usage category identified (44% of objects; mostly glass beverage bottles).
Mostrar más [+] Menos [-]All aboard! A biological survey of ballast water onboard vessels spanning the North Atlantic Ocean Texto completo
2014
Steichen, Jamie L. | Schulze, Anja | Brinkmeyer, Robin | Quigg, Antonietta
Global movement of nonindigenous species, within ballast water tanks across natural barriers, threatens coastal and estuarine ecosystem biodiversity. In 2012, the Port of Houston ranked 10th largest in the world and 2nd in the US (waterborne tonnage). Ballast water was collected from 13 vessels to genetically examine the eukaryotic microorganism diversity being discharged into the Port of Houston, Texas (USA). Vessels took ballast water onboard in North Atlantic Ocean between the Port of Malabo, Africa and Port of New Orleans, Louisiana, (USA). Twenty genera of Protists, Fungi and Animalia were identified from at least 10 phyla. Dinoflagellates were the most diverse and dominant identified (Alexandrium, Exuviaella, Gyrodinium, Heterocapsa, Karlodinium, Pfiesteria and Scrippsiella). We are reporting the first detection of Picobiliphytes, Apusozoa (Amastigomonas) and Sarcinomyces within ballast water. This study supports that global commerce by shipping contributes to long-distance transportation of eukaryotic microorganisms, increasing propagule pressure and invasion supply on ecosystems.
Mostrar más [+] Menos [-]Revisiting methods for the determination of bioavailable metals in coastal sediments Texto completo
2014
Peña-Icart, Mirella | Mendiguchía, Carolina | Villanueva-Tagle, Margarita E. | Pomares-Alfonso, Mario S. | Moreno, Carlos
A simple methodology for the determination of bioavailability of fourteen metals in coastal sediments has been developed by simulating the conditions of digestive process of marine fishes. With this aim, a representative sediment composite sample was treated with hydrochloric acid solutions at different pH values, temperatures and contact times, in the presence and absence of Pepsin and Trypsin. The addition of Pepsin and Trypsin did not affect the extraction of most elements. As a result of the present study, the digestion with a hydrochloric acid solution at pH 1, 40°C and 12h is proposed. Adjustments of the temperature and time reaction could be made according to the specific ecosystem under study. The amount of metal extracted by other methods based on acetic acid was lower than that extracted by HCl treatment proposed.
Mostrar más [+] Menos [-]Assessment of ecological quality of coastal lagoons with a combination of phytobenthic and water quality indices Texto completo
2014
Christia, Chrysoula | Giordani, Gianmarco | Papastergiadou, Eva
Coastal lagoons are ecotones between continents and the sea. Coastal lagoons of Western Greece, subjected to different human pressures, were classified into four different types based on their hydromorphological characteristics and monitored over a three year period for their biotic and abiotic features. Six ecological indices based on water quality parameters (TSI-Chl-a, TSI-TP, TRIX), benthic macrophytes (E-MaQI, EEI-c) and an integrated index TWQI, were applied to assess the ecological status of studied lagoons under real conditions. The trophic status ranged from oligotrophic to hypertrophic according to the index applied. The ecological quality of transitional water ecosystems can be better assessed by using indices based on benthic macrophytes as changes in abundance and diversity of sensitive and tolerant species are the first evidence of incoming eutrophication. The multi-parametric index TWQI can be considered appropriate for the ecological assessment of these ecosystems due to its robustness and the simple application procedure.
Mostrar más [+] Menos [-]Compositions and constituents of freshwater dissolved organic matter isolated by reverse osmosis Texto completo
2014
Zhang, Yulong | Huang, Wen | Ran, Yong | Mao, Jingdong
Dissolved organic matter (DOM) from riverine and lacustrine water was isolated using a reverse osmosis (RO) system. Solid-state 13C nuclear magnetic resonance (13C NMR) was used to quantitatively evaluate the compositions and constituents of DOM, which are compared with previous investigations on marine DOM. Results indicated that concentration factor (CF) was a key metric controlling yield and sorption of DOM on the RO system. The sorption was likely non-selective, based on the 13C NMR and δ13C analyses. Carbohydrates and lipids accounted for 25.0–41.5% and 30.2–46.3% of the identifiable DOM, followed by proteins (18.2–19.8%) and lignin (7.17–12.8%). The freshwater DOM contained much higher alkyl and aromatic C but lower alkoxyl and carboxyl C than marine DOM. The structural difference was not completely accounted for by using structure of high molecular weight (HMW) DOM, suggesting a size change involved in transformations of DOM during the transport from rivers to oceans.
Mostrar más [+] Menos [-]Finite-time compressibility as an agent of frequent spontaneous patch formation in the surface layer: A case study for the Gulf of Finland, the Baltic Sea Texto completo
2014
Giudici, Andrea | Soomere, Tarmo
We explore the possibilities for spontaneous formation of surface patches with high concentrations of contaminants through time correlations of the convergence field and the Lagrangian transport. The test area is the Gulf of Finland, the Baltic Sea, where surface velocity fields show extensive convergence. The flow properties are extracted from 3D velocity fields simulated for 1987–1991 using the OAAS model with a resolution of 1mile. The focus is on the spatial distribution of the areas in which the values of finite-time flow compressibility of surface velocity fields exceed the threshold for clustering of floats. The distribution of such areas is asymmetric, with likely areas of patch formation located predominantly in the southern and eastern regions of the gulf. Out of nine areas of likely patch formation, six are located along the coast in regions of frequent downwelling, while three are identified in the central region of the gulf.
Mostrar más [+] Menos [-]Chemical characterization of roadside PM2.5 and black carbon in Macao during a summer campaign Texto completo
2014
Song, Shaojie | Wu, Ye | Zheng, Xuan | Wang, Zhishi | Yang, Liu | Li, Jiaqi | Hao, Jiming
Air pollution is the leading environmental concern in Macao. The temporal variations of particulate matter (PM) and black carbon (BC) mass concentrations and the size–resolved PM2.5 chemical compositions, including trace elements and carbonaceous species, were measured in Macao during a near–road summer campaign. The average concentrations for PM10, PM2.5 and BC at a roadside measurement site were 37.8μg m−3, 31.4μg m−3 and 5.6μg m−3, respectively. Results showed that local emissions contributed at least 35% to PM2.5 mass in Macao. Higher BC concentrations were observed in the daytime than at night, consistent with the diurnal variations of traffic flow. Factor analysis classified trace elements into three categories, representing crustal sources (Mg, Si, Al, Na, Fe, Ca and K), road traffic sources (Cu and Co) and secondary inorganic particle formation (S). Crustal elements and road traffic elements were enriched in the size ranges of >1.0μm and <0.2μm, respectively. The unimodal distribution pattern with a peak at <0.2μm for organic carbon (OC) was probably due to secondary organic aerosol formation, whereas about 70% of elemental carbon (EC) was in the size range of 0.2–1.0μm. Secondary organic aerosols were found to be a strong contributor to PM in the size ranges of <0.2μm and 1.0–2.5μm.
Mostrar más [+] Menos [-]Workplace personal exposure to respirable PM fraction: a study in sixteen indoor environments Texto completo
2014
Saraga, Dikaia E. | Volanis, Lefteris | Maggos, Thomas | Vasilakos, Christos | Bairachtari, Kyriaki | Helmis, Costas G.
The present paper focuses on respirable particulate matter (RPM) measurements conducted at the breathing zone of adult volunteers in sixteen different working environments: two offices, a house, a chemical laboratory, a non–smoking shop, a pharmacy store, a car garage, a hairdresser's store, a photocopy store, a taxi, a gym, a mall, a restaurant, a bar, a kiosk and a school. The sixteen different cases were categorized according to the location, the type of the activities taking place indoors, the number of occupants, the proximity to heavy traffic roads, the ventilation pattern etc. According to the results, the maximum particle concentration (in average 285μg m−3) was recorded at the hairdresser store while the minimum concentration was measured in the cases of the housewife and the employee in the non–smoking shop (in average 30μg m−3). The results indicated smoking as a factor which strongly influences the exposure levels of both smokers and passive smokers. Furthermore, it was found that the building ventilation pattern comprises an important factor influencing the exposure levels especially in cases of buildings with great number of visitors (resuspension) and smoking.
Mostrar más [+] Menos [-]Mandating responsible flagging practices as a strategy for reducing the risk of coastal oil spills Texto completo
2014
Miller, Dana D. | Hotte, Ngaio | Sumaila, U Rashid
As human civilization is becoming more aware of the negative impact our actions can inflict upon the natural world, the intensification of fossil fuel extraction and industrial development is being met with increasing opposition. In Western Canada, proposals that would increase the volume of petroleum transported by pipelines and by tankers through the coastal waters of British Columbia have engaged the province in debate. To ease public concern on the risk of a coastal oil spill, there are additional commitments that involved parties could make. There is evidence to show that the practice of registering vessels under foreign flags of states that have exhibited failure in compliance with international obligations is more common amongst petroleum tankers that have been involved in large-scale oil spills. To prove that they are committed to reducing the risk of oil spills, businesses need to stop registering their vessels under flags of foreign, non-compliant states.
Mostrar más [+] Menos [-]