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Résultats 2121-2130 de 6,535
Influence of pressure and dispersant on oil biodegradation by a newly isolated Rhodococcus strain from deep-sea sediments of the gulf of Mexico
2020
Hackbusch, Steffen | Noirungsee, Nuttapol | Viamonte, Juan | Sun, Xiaoxu | Bubenheim, Paul | Kostka, Joel E. | Müller, Rudolf | Liese, A. (Andreas)
A new Rhodococcus strain, capable of degrading crude oil, was isolated from the Gulf of Mexico deep-sea sediment and was investigated for its biodegradation characteristics under atmospheric as well as under deep-sea pressure (1500 m = 15 MPa). Additionally, the effect of dispersant (Corexit EC9500A) addition was studied. Rhodococcus sp. PC20 was shown to degrade 60.5 ± 10.7% of the saturated and aromatic fraction of crude oil at atmospheric pressure and 74.2 ± 9.1% at deep-sea level pressure within 96 h. Degradation rates, especially for monoaromatic hydrocarbons, were significantly higher at elevated pressure compared to atmospheric pressure. This study found a growth inhibiting effect at a dispersant to oil ratio of 1:100 and higher. This effect of the dispersant was enhanced when elevated pressure was applied.
Afficher plus [+] Moins [-]Microplastic and tire wear particle occurrence in fishes from an urban estuary: Influence of feeding characteristics on exposure risk
2020
Parker, Brittney W. | Beckingham, Barbara A. | Ingram, Brianna C. | Ballenger, Joseph C. | Weinstein, John E. | Sancho, Gorka
The influence of feeding behavior and feeding ecology on microplastic occurrence in fishes in an urbanized estuary was studied by surveying microplastics in the digestive tracts (gut) of five fish species: the planktivorous Bay Anchovy and Atlantic Menhaden, the piscivore Spotted Seatrout, the benthivore Spot and the detritivore/benthivore Striped Mullet. Microplastics were found in 99% of fishes collected with an average of 27 microplastics per individual fish, 6 microplastics per gram of fish, and 21 microplastics per gram of gut, although exposure varied among species. Atlantic Menhaden possessed significantly more microplastic per fish weight than other species, which may be attributed to their regular ingestion of marine snow aggregates. Fibers were the most common type of microplastic in all fishes, and suspected tire wear particles were found in 14% of individuals across all five species, constituting the first evidence of tire wear particle consumption in field-collected organisms.
Afficher plus [+] Moins [-]Microplastic accumulation in a Zostera marina L. bed at Deerness Sound, Orkney, Scotland
2020
Jones, Katherine L. | Hartl, Mark G.J. | Bell, Michael C. | Capper, Angela
Seagrasses have global distribution and are highly productive and economically valuable habitats. They are sensitive and vulnerable to a range of human-induced pressures, including ongoing exposure to marine litter, such as microplastic particles (<5 mm). In this study, a Zostera marina bed in Deerness Sound, Orkney was selected to determine whether microplastics accumulate in seagrass beds and adhere to seagrass blades. Sediment, seagrass blade, biota and seawater samples were collected. 280 microplastic particles (0.04 to 3.95 mm (mean = 0.95 mm ± 0.05 SE)) were observed in 94% of samples collected (n = 111). These were visually categorised into type (fibre, flake, fragment) and colour, and 50 were successfully identified as plastic using ATR-FTIR. Fibres contributed >50% of the total microplastics observed across all samples. This is the first known study on Z. marina to describe microplastic loading within a seagrass bed and to identify microplastic adherence to seagrass blades.
Afficher plus [+] Moins [-]Total and subcellular Ti distribution and detoxification processes in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil
2020
Monteiro, Fernanda | Lemos, Leila S. | de Moura, Jailson Fulgêncio | Rocha, Rafael Christian Chávez | Moreira, Isabel | Di Beneditto, Ana Paula M. | Kehrig, Helena A. | Bordon, Isabella C. | Siciliano, Salvatore | Saint'Pierre, Tatiana D. | Hauser-Davis, Rachel Ann
Titanium (Ti), used in many dailyuse products, such as shampoos and sunscreen filters, in the form of TiO₂ nanoparticles (NPs), may elicit adverse marine biota effects. Marine mammal Ti data is scarce, and subcellular distribution and detoxification information is non-existent. Ti concentrations and metalloprotein detoxification in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil were assessed. Metallothionein (MT) concentrations were determined spectrophotometrically, total and subcellular Ti, by ICP-MS and detoxification, by HPLC-ICP-MS. Ti detoxification occurred through MT complexation. Statistical Ti-MT associations were observed in S. bredanensis liver, indicating TiO₂ NPs contamination, as Ti binds to MT only as NPs. MT-Ti correlations were observed for both the coastal (P. blainvillei) and offshore (S. bredanensis) dolphins, evidencing oceanic TiO₂ diffusion. Ti detoxification through binding to reduced glutathione occurred in both species. Thermostable subcellular fractions are a valuable tool for cetacean Ti detoxification assessments and should be applied to conservation efforts.
Afficher plus [+] Moins [-]Determination of linear alkylbenzenes (LABs) in mangrove ecosystems using the oyster Crassostrea belcheri as a biosensor
2020
Alkhadher, Sadeq Abdullah Abdo | Kadir, Aeslina Abdul | Zakaria, Mohamad Pauzi | Al-Gheethi, Adel | Asghar, Basim Hussain Mustafa
The current study aimed to develop a suitable molecular marker [Linear alkylbenzenes (LABs)] approach for pollution determination in mangrove oysters of peninsular Malaysia. C. belcheri species were collected from rivers of Merbok, Perai, Klang, Muar and PulauMerambong (An Island). The LABs were extracted from C. belcheri and determined using GC–MS. The LABs indices which included I/E, L/S and C13/C12 were applied to describe the sources and biodegradation of LABs. The results revealed that the maximum concentrations were detected in oysters from Klang (27.91 ng g⁻¹dw), while the lowest concentrations were detected in oysters from Merbok (8.12 ng g⁻¹dw). Moreover, I/E ratios varied between 2.83 and 6.40, indicating the secondary treatment effluents being discharged to coastal zones. The results of this study suggested that the oysters absorbed LABs mainly in dissolved phase. Therefore, mangrove oysters are a good biosensor for LABs contamination in the aquatic environment.
Afficher plus [+] Moins [-]Heavy metals contamination of sedimentary microplastics in Hong Kong
2020
Li, Wenjie | Lo, Hoi-Shing | Wong, Ho-Man | Zhou, Man | Wong, Chun-Yuen | Tam, Nora Fung-Yee | Cheung, Siu-Gin
This is the first study of heavy metals (As, Zn, Cd, Ni, Fe, Mn, Cu) contamination of microplastics on sandy beaches in Hong Kong. Three study sites are located in the eastern waters (Pak Lap Wan, Stanley Bay, Tung Lung Chau) and the other three in the western waters (Tai Pai Tsui, Ha Pak Nai, Shui Hau Wan). The three most abundant types of microplastics were polyethylene (42.2%), polypropylene (23.3%) and polystyrene (19.5%). The median concentration of Fe (302 mg kg⁻¹) was the highest and followed by Zn (19.6 mg kg⁻¹) and Mn (18.6 mg kg⁻¹). Very low concentrations of Cu (0.89 mg kg⁻¹), Ni (0.15 mg kg⁻¹), As (<LOD) and Cd (<LOD) were measured. The western sites have significantly higher concentrations of Ni, Fe, Mn and Cu than the eastern sites, indicating that Pearl River was likely to be a major source of heavy metals on microplastics. In view of a continual increase in the abundance of microplastics in the marine environment and its potential impacts on marine organisms, immediate actions should be taken in establishing long term monitoring programs for heavy metals associated with microplastics. In-depth research on the mechanisms of adsorption and desorption processes between metals and microplastics will help assess the associated risks to both human health and the environment.
Afficher plus [+] Moins [-]Trace element distribution in marine microplastics using laser ablation-ICP-MS
2020
El Hadri, Hind | Gigault, Julien | Mounicou, Sandra | Grassl, Bruno | Reynaud, Stéphanie
Due to the dramatic quantity of plastic debris released into our environment, one of the biggest challenges of the next decades is to trace and quantify microplastics (MPs) in our environments, especially to better evaluate their capacity to transport other contaminants such as trace metals. In this study, trace elements (Fe, Cu, Zn, As, Cd, Sn, Sb, Pb, and U) were analyzed in the microplastic subsurface (200 μm) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Microplastics subjected to the marine environment were collected on beaches (Guadeloupe) exposed to the north Atlantic gyre. We established a strategy to discriminate sorbed contaminants from additives based on the metal concentration profiles in MP subsurface using qualitative and quantitative approaches. A spatiotemporal correlation of the sorption pattern was proposed to compare MPs in terms of relative exposure time and time-weighted average concentrations in the exposure media.
Afficher plus [+] Moins [-]First detection of microplastics in the freshwater of an Antarctic Specially Protected Area
2020
González-Pleiter, Miguel | Edo, Carlos | Velázquez, David | Casero-Chamorro, María Cristina | Leganés, Francisco | Quesada, Antonio | Fernández-Piñas, Francisca | Rossal S., J. Roberto (Julio Roberto Rossal Salazar)
Microplastics have been found in all environmental compartments investigated so far, even reaching remote areas. However, their presence in Antarctic freshwaters has not been yet reported. Here, we investigated the occurrence of microplastics in a stream from an Antarctic Specially Protected Area (Byers Peninsula, Livingston Island - ASPA No. 126), which is subject to stringent environmental protection measures as a result of which it is considered a pristine international reference site for inland waters research. Our results showed the presence of three types of microplastics in a freshwater seasonal stream, namely four polyester fibers, one black and three transparent; two acrylic fibers, one transparent and one red; and two transparent polytetrafluoroethylene films. The length and width of these fibers and films were in the 400–3546 μm (average 1118 μm), and 10–1026 μm (average 199 μm) ranges respectively. The concentration of MP was 0.95 items/1000 m³ with estimated variability in the 0.47–1.43 items/1000 m³ range. This is the first report of the presence of microplastics in Antarctic freshwater with the uniqueness that it is an Antarctic Specially Protected Area, meaning that plastic pollution reached even the most remote and pristine environments in the planet.
Afficher plus [+] Moins [-]Selection of oil spill response method in Arctic offshore waters: A fuzzy decision tree based framework
2020
Hu, Guangji | Mohammadiun, Saeed | Gharahbagh, Abdorreza Alavi | Li, Jianbing | Hewage, Kasun | Sadiq, Rehan
A fuzzy decision tree (FDT) based framework was developed to facilitate the selection of suitable oil spill response methods in the Arctic. Hypothetical oil spill cases were developed based on six identified attributes, while the suitability of three spill response methods (mechanical containment and recovery, use of chemical dispersants, and in-situ burning) for each spill case was obtained based on expert judgments. Fuzzy sets were used to address the associated uncertainties, and FDTs were then developed through generating: i) one decision tree for all three response methods (FDT-AP1) and ii) one decision tree for each response method and the development of linear regression models at terminal nodes (FDT-LR). The FDT-LR approach exhibited higher prediction accuracy than the FDT-AP1 approach. A maximum of 100% accurate predictions could be achieved for testing cases using it. On average, 75% of suitable oil spill response methods out of 10,000 performed iterations were predicted correctly.
Afficher plus [+] Moins [-]Nano-Catalysts in Ozone-Based Advanced Oxidation Processes for Wastewater Treatment
2020
Dang, Thi Thom | Do, Van Manh | Trinh, Van Tuyen
PURPOSE OF REVIEW: Pollution is now being varied with huge contaminants in wastewater especially with kind of recalcitrants that are emerging pollutants needed new advanced resolutions to mineralize them completely. Thus, the investigation of technology and technique processes is very important for research and development. Moreover, these manual, research, and application of the advanced oxidation processes especially using ozone for water and wastewater are concentrated and appreciated in over the world. Recently, nanoparticles have researched into subjects to enhance new, advanced technology for many domains such as environment, biology, agriculture, and medicine. Hence, the purpose of this review is to summarize the important role of nano-particulars as nano-catalysts in ozone-based advanced oxidation processes for wastewater treatment and evaluate how to contribute into ozone-based advance oxidation processes by nano-catalysts for wastewater treatment. RECENT FINDINGS: The advanced oxidation processes (AOPs) for wastewater treatment nowadays are being appreciated in the twenty-first century when economy development day by day is concentrated extremely in industry, agriculture, and pharmacy leading to various pollutants in the environment. According to these developments, amount of various contaminants is discharged in wastewater; thus, investigation of advance technology based on nano-catalysts combining the ozonation will meet the demands for wastewater treatment. This review found potentials and prospects of nano-catalysts applied in the catalytic ozonation process for wastewater treatment. Efficiency of some well-known nano-catalysts with analytical properties for catalytic ozonation is also evaluated. Mechanisms of this process are identified to easily approach the catalytic ozonation using nano-materials for wastewater treatment in the future.
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