خيارات البحث
النتائج 1681 - 1690 من 5,014
Two-dimensional distribution and abundance of micro- and mesoplastic pollution in the surface sediment of Xialiao Beach, New Taipei City, Taiwan النص الكامل
2019
Bancin, Lamtiur Junita | Walther, Bruno A. | Lee, Yao-Chang | Kunz, Alexander
Environmental pollution with plastic is a growing problem worldwide. This study investigates the microplastic and mesoplastic pollution of Xialiao Beach in northern Taiwan. Sand from the surface (1 cm depth) was collected in a systematic manner. A total of 80 samples were taken along four transects, and plastic particles (≥1 mm) were extracted and quantified. In total, 1939 microplastic particles were recovered, with an average of 96.8 particles per 1 m2. Statistical analysis showed that the backshore had significantly more microplastic particles than the supra littoral or intertidal. Extrapolating the numbers of plastic particles found, approximately 6.8 million plastic particles (≥1 mm) weighing about 250.4 kg should be found in the surface layer of Xialiao Beach. Resampling curves were created from the data set, which showed that at minimum 20 samples should be taken to adequately estimate the mean particle abundance.
اظهر المزيد [+] اقل [-]Combined releases of oil and gas under pressure; the influence of live oil and natural gas on initial oil droplet formation النص الكامل
2019
Brandvik, Per Johan | Storey, Chris | Davies, Emlyn John | Johansen, Øistein
Both oil droplets and gas bubbles have simultaneously been quantified in laboratory experiments that simulate deep-water subsea releases of both live oil (saturated with gas) and additional natural gas under high pressure. These data have been used to calculate particle size distributions (50–5000 μm) for both oil and gas. The experiments showed no significant difference in oil droplet sizes versus pressure (from 5 m to 1750 m) for experiments with live oil. For combined releases of live oil and natural gas, oil droplet sizes showed a clear reduction as a function of increased gas void fraction (increased release velocity) and a weak reduction with increased depth (increased gas density/momentum). Oil droplets were reduced by a factor of 3 to 4 during simulated subsea dispersant injection (SSDI) and no significant effect of pressure was observed. This indicates that SSDI effectiveness is not dependent on water depth or pressure.
اظهر المزيد [+] اقل [-]Risk assessment for ballast water management — Learning from the Adriatic Sea case study النص الكامل
2019
David, Matej | Gollasch, Stephan
The ballast water management convention incorporates principles of risk assessment. A new ballast water management risk assessment model was developed to support the implementation of most efficient management measures, which we also present as a flowchart decision support system model. The risk assessment model was tested using data from port baseline surveys where available, and real shipping and ballast water discharges data. The here presented ballast water management risk assessment and possible management options are applicable elsewhere to support and improve complex decision making in the implementation of management requirements according to the ballast water management convention. If needed, the model may easy be adapted to address local specifics in any other region or area.
اظهر المزيد [+] اقل [-]Nearshore sea surface macro marine debris in Maui County, Hawaii: Distribution, drivers, and polymer composition النص الكامل
2019
Currie, Jens J. | Stack, Stephanie H. | Brignac, Kayla C. | Lynch, Jennifer M.
Located within the subtropical convergence zone, the Hawaiian archipelago is subject to high debris loads. This paper represents the first study to determine the spatial and temporal trends of floating macro debris quantities and polymer composition within Maui County waters. Ocean surveys were conducted from 2013 to 2017 and collected 2095 debris items of which 90% were plastic. Attempts to categorize items by source resulted in only 6% likely from land, 12% from ocean-based sources, 50% from either land or ocean, and 32% from unknown sources. Results found a multi-step process for debris accumulation, with temporal trends linked to survey day and year and spatial trends linked to ocean processes. High- and low-density polyethylene and polypropylene accounted for the majority of polymer types. The results of this study demonstrate minimal debris in Maui originates from land/local sources, and the importance of baseline data to guide further research and mitigation measures.
اظهر المزيد [+] اقل [-]Marine litter in sediments related to ecological features in impacted sites and marine protected areas (Croatia) النص الكامل
2019
Renzi, Monia | Čižmek, Hrvoje | Blašković, Andrea
This study estimates levels of marine litter including plastics (macro-, meso- and microplastics) in sediments collected in shallow marine water from Croatia (Central Adriatic Sea). Selected sampling areas are characterized by different human pressure: Silba is highly stressed by tourism while Grebena is listed as marine protected area (MPA) of future institution. Obtained results on marine litter in sediments are correlated to ecological features recorded in each sampling site. Marine litter in collected sediments ranged within 180–528 items/kg d.w. Macroplastics were not recorded while mesoplastics were 1.3–4.8%. On a general basis, fibres are higher than microplastics. In Južni Greben, level of fragments higher than fibres was recorded. A slight significance of the factor “water depth” was evidenced by the statistical analyses exploring relationships among marine litter and ecological features. Furthermore, Silba and Grebena Islands showed a significant different assessment of size, shape and colour features. These results suggest different sources/dynamics affecting marine litter recorded in marine areas stressed by tourism compared to MPA.
اظهر المزيد [+] اقل [-]Heavy metal tolerance and polychlorinated biphenyl oxidation in bacterial communities inhabiting the Pasvik River and the Varanger Fjord area (Arctic Norway) النص الكامل
2019
Rappazzo, Alessandro Ciro | Papale, Maria | Rizzo, Carmen | Conte, Antonella | Giannarelli, Stefania | Onor, Massimo | Abete, Carlo | Cefali, Pietro | De Domenico, E. (Emilio) | Michaud, Luigi | Lo Giudice, Angelina
Heavy metals (HMs) and polychlorobiphenyls (PCBs) enter the Arctic environment through a variety of anthropogenic sources with deleterious effects towards biota and public health. Bacteria first transfer toxic compounds to higher trophic levels and, due to the tight link existing between prokaryotic community functions and the type and concentration of contaminants, they may be useful indicator of pollution events and potential toxicity to other forms of life. The occurrence and abundance of HM-tolerant and PCB-oxidizing bacteria in the sub-Arctic Pasvik river area, heavily impacted by anthropogenic modifications, was related to HM and PCB contamination. This latter more likely derived from local inputs rather than a global contamination with higher PCB and HM amounts (and higher bacterial viable counts) that were determined in inner and middle sections of the River. Finally, a panel of bacteria with potential applications in the bioremediation of cold environments were selected and phylogenetically identified.
اظهر المزيد [+] اقل [-]Ingestion of macroplastic debris by the common dolphinfish (Coryphaena hippurus) in the Western Equatorial Atlantic النص الكامل
2019
Menezes, Rafael | da Cunha-Neto, Manuel Alves | de Mesquita, Grazielly Campos | da Silva, Guelson Batista
We report the occurrence of macroplastic debris in the stomach of a common dolphinfish (Coryphaena hippurus) caught in the Western Equatorial Atlantic. On the deck, we noticed that the fish was remarkably undernourished and decided to remove its stomach for laboratory analysis. A large part of a plastic bowl and a tuna pectoral fin were the only items recorded in the fish stomach. The plastic measured 99.57 cm2 and weighed 12.77 g, likely blocking the digestive tract and reducing food intake by the fish, as supported by signs of starvation. This is the record of the largest plastic debris ingested by a dolphinfish to date. As the source of the plastic container was probably a tuna fishing boat, we suggest strengthening environmental education programs to enhance the awareness of fishermen and mitigate the impacts of plastic pollution on the pelagic ecosystem and associated organisms, such as C. hippurus.
اظهر المزيد [+] اقل [-]Large debris dumps in the northern South China Sea النص الكامل
2019
Peng, X. | Dasgupta, S. | Zhong, G. | Du, M. | Xu, H. | Chen, M. | Chen, S. | Ta, K. | Li, J.
Knowledge of the abundance, source, and fate of marine debris in the deep sea is largely constrained thus far. Here, we report the existence of large deep-sea debris dumps that have not been reported before on the seafloor worldwide. Marine debris remarkably accumulated at ~1700–1800 m in the tributary submarine canyons of the Xisha Trough, northern South China Sea (SCS). Although marine debris in Xisha Trough is patchy, the debris abundance was as high as 36,818 and 51,929 items/km² at locations SY78 and SY82, respectively, which is one order of magnitude higher than that in other submarine canyons. We propose that most of the debris came from fishery and navigation activities, as indicated by the categories of debris collected from the seafloor dumps. Seasonal surface ocean currents of the SCS and geomorphology of submarine canyons possibly influence the movement of the debris from coasts to the deep seafloor.
اظهر المزيد [+] اقل [-]Ingestion of microplastics by fish and other prey organisms of cetaceans, exemplified for two large baleen whale species النص الكامل
2019
Burkhardt-Holm, P. | N'Guyen, A.
Knowledge on microplastic (MP) ingestion by cetaceans is difficult to obtain. We infer the potential for MP uptake by cetaceans from the occurrence of MP in prey species. First, we reviewed information on whale prey species, focussing on common minke (Balaenoptera acutorostrata) and sei whale (B. borealis), for which the most comprehensive quantitative datasets exist. Second, evidence of MP ingestion by their prey species was reviewed. We found common minke whales forage opportunistically on fish from various families: Ammodytidae, Clupeidae, Gadidae, Engraulidae and Osmeridae. Sei whales mostly feed on copepods, Engraulidae, Clupeidae and Scombridae. High levels of MP contamination are reported for Scombridae in the Atlantic and Engraulidae in the Northwest Pacific Ocean. Copepods exhibit low levels of MP ingestion in the Northeast Pacific Ocean. Species-specific prey preferences and feeding strategies imply different cetaceans have varied potential for MP uptake, even if they feed in similar geographic areas.
اظهر المزيد [+] اقل [-]Microplastics occurrence in edible fish species (Mullus barbatus and Merluccius merluccius) collected in three different geographical sub-areas of the Mediterranean Sea النص الكامل
2019
Giani, Dario | Baini, Matteo | Galli, Matteo | Casini, Silvia | Fossi, Maria Cristina
The gastrointestinal tracts of 229 demersal fish belonging to two species (Mullus barbatus, Merluccius merluccius) were examined for microplastic ingestion. Samples were collected in 3 different FAO Geographical Sub-Areas (GSA-9, GSA-17, GSA-19) of the Mediterranean Sea. Ingested microplastics were characterized using a stereo-microscope: observed, photographed, measured and categorized according to size class, shape and colour. Plastic fragments (ranging from 0.10 to 6.6 mm) were detected in 23.3% of the total investigated fish; a total of 65 plastic particles (66% constituted by fibers) were recorded. The percentage of plastic ingestion shows high variability between the two species and among the different sampling area. The highest frequency (48%) was found in European hake from GSA-19. These preliminary results represent a baseline for the implementation of the Marine Strategy Framework Directive descriptor 10 in Italy as well as an important step for detecting microplastics in bioindicator species from different GSAs.
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