خيارات البحث
النتائج 1551 - 1560 من 4,940
Ecotoxicological benthic impacts of experimental oil-contaminated marine snow deposition
2019
van Eenennaam, Justine S. | Rohal, Melissa | Montagna, Paul A. | Radović, Jagoš R. | Oldenburg, Thomas B.P. | Romero, Isabel C. | Murk, AlberTinka J. | Foekema, Edwin M.
Marine Oil Snow Sedimentation and Flocculent Accumulation (MOSSFA) can pose serious threats to the marine benthic ecosystem as it results in a deposition of oil contaminated marine snow on the sediment surface. In a microcosm experiment we investigated the effects of oil in combination with artificial marine snow or kaolin clay on two benthic invertebrate species and benthic meiofauna. The amphipod showed a dose-dependent decrease in survival for both oil-contaminated clay and oil-contaminated marine snow. The gastropod was only affected by the highest concentration of oil-contaminated marine snow and had internal concentrations of PAHs with a similar distribution as oil-contaminated marine snow. Benthic copepods showed higher survival in presence of marine snow. This study revealed that marine snow on the sediment after oil spills affects organisms in a trait-dependent way and that it can be a vector for introducing oil into the food web.
اظهر المزيد [+] اقل [-]Inter-hemispherical shoreline surveys of anthropogenic marine debris – A binational citizen science project with schoolchildren
2019
Honorato-Zimmer, Daniela | Kruse, Katrin | Knickmeier, Katrin | Weinmann, Anna | Hinojosa, Ivan A. | Thiel, Martin
Anthropogenic marine debris (AMD) is a global problem and the identification of its sources is essential for adequate mitigation strategies. Herein we examined whether AMD density and composition differed between two countries with contrasting socio-economic backgrounds and marine litter sources (i.e. Chile and Germany). In nationwide beach litter surveys, we used a citizen science approach with schoolchildren and their teachers. Litter densities were substantially higher in Chile than in Germany. The different geographic zones surveyed in both countries showed strong grouping tendencies according to their main economic activities (tourism, shipping, fisheries/aquaculture), major litter sources, and AMD composition, in terms of dominance and diversity of AMD types. The results suggest that beach litter composition can be used as a simple proxy to identify AMD sources, and also that law enforcement and education can help mitigate the problem; however, for efficient solutions, production and consumption of plastics must be reduced.
اظهر المزيد [+] اقل [-]Impact of emission control areas on atmospheric pollutant emissions from major ocean-going ships entering the Shanghai Port, China
2019
Wan, Zheng | Zhang, Qiang | Xu, Zhipeng | Chen, Jihong | Wang, Qin
Ocean-going ships are mostly driven by high‑sulfur heavy fuel oil, which poses public health and environmental concerns. Emission control areas (ECA) have been developed for the regulatory control of the sulfur content in fuel. We tracked 28 sample vessels that entered and exited Shanghai Port, to understand how air pollutants, including oxysulfides (SOx), nitric oxide (NOx), and particulate matter smaller than 10 μm (PM₁₀), would change under the ECA regulations. Emission reductions vary with the types and sizes of the ships. In our sample pool, oil/chemical tankers and container ships have the highest decline rates of SOx emissions at 26.8%–56.4% and 17.4%–56.6%, respectively. Cruise ships, container ships, and liquefied gas carriers occupy the highest share ratios of pollutant emissions in the sample pool because of the higher average gross tonnage and correspondingly higher-rated power of the ships' main engines. As expected, SOx and PM₁₀ emissions under hoteling conditions (operations while stationary at dock) can be considerably reduced by switching to low-sulfur fuel. Using fuel with the much lower sulfur content of 0.1% m/m in the ECA, the SOx and PM₁₀ emissions of our sample pool could be reduced considerably by up to 94.4% and 78.3%, respectively, compared to the 0.5% m/m sulfur content used during ship hoteling.
اظهر المزيد [+] اقل [-]Large impact of Stokes drift on the fate of surface floating debris in the South Indian Basin
2019
Dobler, Delphine | Huck, Thierry | Maes, Christophe | Grima, Nicolas | Blanke, Bruno | Martinez, Elodie | Ardhuin, Fabrice
In the open ocean, floating surface debris such as plastics concentrate in five main accumulation zones centered around 30° latitude, far from highly turbulent areas. Using Lagrangian advection of numerical particles by surface currents from ocean model reanalysis, previous studies have shown long-distance connection from the accumulation zones of the South Indian to the South Pacific oceans. An important physical process affecting surface particles but missing in such analyses is wave-induced Stokes drift. Taking into account surface Stokes drift from a wave model reanalysis radically changes the fate of South Indian particles. The convergence region moves from the east to the west of the basin, so particles leak to the South Atlantic rather than the South Pacific. Stokes drift changes the South Indian sensitive balance between Ekman convergence and turbulent diffusion processes, inducing either westward entrainment in the north of the accumulation zone, or eastward entrainment in the south.
اظهر المزيد [+] اقل [-]Tracing underground sources of pollution to coastal waters off Map Ta Phut, Rayong, Thailand
2019
Burnett, William C. | Sola, Phachirarat | Chanyotha, Supitcha | Bidorn, Butsawan | Kritsananuwat, Rawiwan | Chinfak, Narainrit
We explored the possibility that an underground pathway, “submarine groundwater discharge” (SGD), may contribute to the observed coastal contamination from a large industrial complex on the Gulf of Thailand. Three surveys were performed to map the area for the natural groundwater tracers radon, thoron and salinity. The results from all three surveys were internally consistent showing a point source adjacent to a large pier that serves the complex. It may be that a piling, driven into the ground to support the pier, intercepted a shallow aquifer and this resulted in an underground pathway between land and sea. Some low-density sediments are enriched in radium, we suspect from fly ash from a nearby power plant. Water quality parameters showed that total petroleum hydrocarbons (TPHs) correlated strongly to nitrite, dissolved inorganic phosphate and silica, indicating a common source. Data analysis shows that diffuse seepage accounts for more discharge than the point source.
اظهر المزيد [+] اقل [-]Diversity and abundance of antibiotic resistance of bacteria during the seedling period in marine fish cage-culture areas of Hainan, China
2019
Wu, Jinjun | Mao, Can | Deng, Yiqin | Guo, Zhixun | Liu, Guangfeng | Xu, Liwen | Bei, Lei | Su, Youlu | Feng, Juan
Antibiotic resistance has become an important focus of research in the aquaculture environment. However, few studies have evaluated antibiotic resistance during the seedling period in marine fish cage-culture areas. In this study, culture-dependent methods and quantitative polymerase chain reaction were used to identify and detect cultivable heterotrophic antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs), respectively, during the seedling period in a marine fish cage-culture areas of Hainan, China. Bacterial resistance to amoxicillin, erythromycin, and gentamicin was generally high (average on 27.67%, 23.61% and 37.32%, respectively), whereas resistance to furazolidone and nitrofurantoin was generally low (average on 0.14% and 7.425%). Alteromonas (32.72%) and Vibrio (24.77%) were the dominant genus of ARB. Most ARB were opportunistic pathogens, belonging to the phylum Proteobacteria (96.02%). The abundance of sul family genes was higher than that of tet family genes. Overall, the abundance of ARGs and the resistance rates in HW was highest.
اظهر المزيد [+] اقل [-]Influence of sediment parameters on the distribution and fate of PAHs in an estuarine tropical region located in the Brazilian semi-arid (Jaguaribe River, Ceará coast)
2019
Andrade, Márcia V.F. | Santos, Felipe R. | Oliveira, André H.B. | Nascimento, Ronaldo F. | Cavalcante, Rivelino M.
18 polycyclic aromatic hydrocarbons (PAHs) were evaluated in the Jaguaribe River to explore the influence of grain size, organic carbon, humic and fulvic acids and black carbon on their adsorption onto sediment. The ∑PAHs concentrations variated from 0.6 to 3752.0 ng g⁻¹ with highest concentrations in the estuarine zone. The PAHs predominant source along the river was from mixed sources, mainly related to biomass combustion, small oil spills related to recreational nautical activities and runoff from cities. Organic and inorganic parameters presented influence on PAHs distribution along the river, with humic acid as a determinant factor. These research findings are of importance to an assessment of the fate and transport of PAHs in estuarine systems.
اظهر المزيد [+] اقل [-]Sorption of polyhalogenated carbazoles (PHCs) to microplastics
2019
Qiu, Ying | Zheng, Minggang | Wang, Ling | Zhao, Quansheng | Lou, Yinghua | Shi, Lei | Qu, Lingyun
The sorption of 5 Polyhalogenated carbazoles (PHCs) [3,6-dibromocarbazole (3,6-BCZ), 3,6-dichlorocarbazole (3,6-CCZ), 3,6-diiodocarbazole (3,6-ICZ), 2,7-dibromocarbazole (2,7-BCZ) and 3-bromocarbazole (3-BCZ)] on to three microplastics [polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC)] in a simulated seawater system are studied. Sorption isotherms demonstrated that PVC had the maximum sorption capacity, which can be attributed to polar-polar interaction. The sorption kinetics model showed that the sorption process was controlled by both intraparticle and film diffusion. The sorption of PHCs to microplastics was significantly influenced by temperature, the sorption capacity first increased gradually and then decreased with the increasing temperature. Increasing the salinity decreased the sorption of PHCs onto PP, PE, PVC microplastics. Our results indicated that all three kinds of microplastics can serve as carriers for PHCs in the aquatic environment, which put marine ecosystems at higher risks.
اظهر المزيد [+] اقل [-]The implementation of the ballast water management convention in the Adriatic Sea through States' cooperation: The contribution of environmental law and institutions
2019
Rak, Giulietta | Zec, Damir | Markovčić Kostelac, Maja | Joksimović, Darinka | Gollasch, Stephan | David, Matej
The Adriatic Sea, a semi-enclosed and vulnerable environment, deserves special attention regarding the risk of introducing Harmful Aquatic Organisms and Pathogens via ships' ballast water as new species findings occur at an alarming rate. This species introduction vector was addressed with the 2004 International Convention for the Control and Management of Ships' Ballast Water and Sediments, which entered into force in 2017. The efficient implementation of this convention calls for Adriatic States' cooperation on environmental specifics that have not been dealt with neither by national nor by international measures yet. Based on legal and institutional data gathered, and considering the regional maritime traffic and environmental specifics, this paper reveals that the integration of current environmental law commitments as well as a better dialogue between public institutions from shipping and environmental sectors may foster the implementation of ballast water management obligations through appropriate Adriatic States' cooperation.
اظهر المزيد [+] اقل [-]Comparison of persistent organic pollutants (POPs) between small cetaceans in coastal and estuarine waters of the northern Gulf of Mexico
2019
Balmer, Brian | Ylitalo, Gina | Watwood, Stephanie | Quigley, Brian | Bolton, Jennie | Mullin, Keith | Rosel, Patricia | Rowles, Teri | Speakman, Todd | Wilcox, Lynsey | Zolman, Eric | Schwacke, Lorelei H.
Small cetaceans continue to be exposed to elevated levels of persistent organic pollutants (POPs). The goals of this study were to use data from remote biopsy sampling and photographic-identification to compare POP concentrations between small cetacean stocks in the northern Gulf of Mexico. During 2015–2017, 74 remote biopsies were collected in St. Andrew Bay and adjacent coastal waters from two species: common bottlenose dolphin (Tursiops truncatus) (N = 28, ♀; N = 42, ♂) and Atlantic spotted dolphin (Stenella frontalis) (N = 2, ♀; N = 2, ♂). Common bottlenose dolphin POP concentrations were significantly higher in St. Andrew Bay than coastal waters. Male St. Andrew Bay dolphins had the highest Σ DDT (dichlorodiphenyl-dichloroethane) levels measured in the southeastern U.S. (67 μg/g, 50–89 μg/g; geometric mean and 95% CI) and showed a significant negative relationship between Σ DDT and sighting distance from a St. Andrew Bay point source.
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