خيارات البحث
النتائج 1881 - 1890 من 4,896
Historical records of trace metals in core sediments from Jiangsu coastal area, China
2019
Qiu, Jiandong | Yin, Ping | Liu, Jinqing | Cao, Ke | Li, Meina | Wang, Shuang
The major and trace metal (Cu, Pb, Zn, Cr, Cd, As, Hg, Ni, Li, and Co) concentration profiles along a 60.2-m-long sediment core are investigated to assess their depositional trends and contamination levels in the Jiangsu coastal area, China. All of the metals, except Cd, had similar profiles that exhibited increasing concentrations during the Holocene. Their enrichment factors indicate that the metals were naturally sourced throughout the observed depositional period, with the exception of As, Hg, and Li, which may have also had anthropogenic sources. Their geoaccumulation indices indicate that the sediments were not contaminated by any metals prior to the Holocene, whereas they were contaminated by As, Hg, and Li throughout the Holocene (11–0 ka), and by Pb, Cr, and Zn since 2 ka.
اظهر المزيد [+] اقل [-]Plastic ingestion in seabirds of the western Indian Ocean
2019
Cartraud, Audrey E. | Le Corre, Matthieu | Turquet, Jean | Tourmetz, Julie
We investigated seabird plastic ingestion in the western Indian Ocean by analyzing the stomach contents of 222 individuals belonging to nine seabird species (including two endangered species endemics to Reunion Island). The most affected species were tropical shearwaters (79%) and Barau's petrels (59%). The average number of plastic particles per contaminated bird was higher in Barau's petrels (6.10 ± 1.29) than in tropical shearwaters (3.84 ± 0.59). All other studied species also showed plastic presence in their stomach contents. The mass of plastic particles was significantly higher both in juvenile's Barau's petrels and tropical shearwaters than in adults. These results demonstrate the foraging areas of seabirds of the western Indian Ocean have a high level of plastic pollution. In Reunion Island, hundreds of tropical shearwaters and Barau's petrels are attracted by urban lights and die each year. We suggest taking advantage of this situation by using these species as long-term indicators of plastic marine pollution in the region.
اظهر المزيد [+] اقل [-]Piece-by-piece analysis of additives and manufacturing byproducts in plastics ingested by seabirds: Implication for risk of exposure to seabirds
2019
Tanaka, Kosuke | van Franeker, Jan A. | Deguchi, Tomohiro | Takada, Hideshige
The risk of marine organisms ingesting plastics has become a growing concern due to hazard chemicals in plastics. To identify compounds to which seabirds potentially have substantial exposure, 194 plastics fragments and pellets ingested by seabirds, i.e., northern fulmars from the Faroe Islands, and laysan albatross and black-footed albatross from Mukojima Island, were analyzed piece by piece. Four kinds of UV stabilizers, 2 brominated flame retardants, and styrene oligomers were detected at detection frequencies of 4.6%, 2.1%, and 2.1%, respectively. Concentrations ranging from not detected (n.d.) – 1700 μg/g were measured for UV stabilizers, n.d. – 1100 μg/g for flame retardants, and n.d. – 3200 μg/g for styrene oligomers. We found that these chemicals could be retained in plastics during drifting and fragmentation in the ocean and transported to seabirds. This type of transport via plastics can be direct pathway that introduces hazardous compounds to marine organisms.
اظهر المزيد [+] اقل [-]A feedback-controlling digital microfluidic fluorimetric sensor device for simple and rapid detection of mercury (II) in costal seawater
2019
Zhang, Qian | Zhang, Xingcai | Zhang, Xiaolin | Jiang, Lan | Yin, Jingmei | Zhang, Peng | Han, Shuang | Wang, Yunhua | Zheng, Guoxia
By combination of miniaturization potential of digital microfluidics (DMF) and sensitivity of fluorescence probe, an integrated sensor device has been initially constructed for mercury detection in coastal waters. The actuation feature of the detecting target, seawater droplet, which remains unclear, was basically explored. To overcome a potential risk of driven failure, induced by diversity ion ingredients in seawater, a feedback control loop was included into control system. Analyzing method for coastal waters was well established on DMF, which showed satisfied stability and selectivity in Hg sensing under high salinity condition, with the sensitivity of Hg²⁺ at the parts per billion level and total testing time less than 20s. With the advantages of being fast, amenable to automation and low cost, this device is promising for the formation of simple and rapid sensor device, especially for a routine monitoring and emergency detection of Hg/or other metals in coastal waters.
اظهر المزيد [+] اقل [-]The influence of microplastics pollution on the feeding behavior of a prominent sandy beach amphipod, Orchestoidea tuberculata (Nicolet, 1849)
2019
Carrasco, Alejandra | Pulgar, José | Quintanilla-Ahumada, Diego | Perez-Venegas, Diego | Quijón, Pedro A. | Duarte, Cristian
Pollution by microplastics has become a global threat affecting coastal habitats such as sandy beaches and their resident macrofauna. The goal of this study was to assess the influence of microplastics on the feeding behavior and growth rate of a widespread sandy beach amphipod, Orchestoidea tuberculata. These organisms were exposed to artificial food prepared with Poly(styrene-co-divinylbenzene) microspheres (8 μm particle size) at 3 different concentrations (0%, 5% and 10%). The amphipods consumed significantly more food when the concentration of microplastics was 0% and significantly less when the concentration was 10%, both in trials in which they had a choice (preference experiments) and those in which they did not have a food choice. In contrast to this, the amphipod's absorption efficiency and estimated growth rates were not significantly affected by the concentration of microplastics. Combined, these results indicate that high microplastics concentrations (e.g. 10%) cause a reduction in the amphipod's consumption rates and, indirectly, may affect the role of this species as a main consumer of stranded seaweeds in sandy beaches ecosystems.
اظهر المزيد [+] اقل [-]Ingestion of microplastics by fish and other prey organisms of cetaceans, exemplified for two large baleen whale species
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 [-]Differences in Symbiodiniaceae communities and photosynthesis following thermal bleaching of massive corals in the northern part of the South China Sea
2019
Gong, Sanqiang | Xu, Lijia | Yu, Kefu | Zhang, Fengli | Li, Zhiyong
Although many achievements have been made in studies on the relationship between Symbiodiniaceae and coral bleaching, there is little information on the responses of Symbiodiniaceae to coral thermal bleaching in the South China Sea (SCS). In this study, Symbiodiniaceae communities and the effective quantum yield (ФPSII) of healthy and bleached massive corals from the SCS were compared. The results indicated that the Symbiodiniaceae communities and ФPSII values showed coral bleaching-dependent variations. Specifically, the relative abundances of the rare putatively thermally tolerant Durusdinium sp. (D1) and the Symbiochlorum hainanensis increased significantly in the bleached corals. In addition, bleached Porites lutea was mainly associated with the putatively thermally tolerant Cladocopium sp. (C15 and C91) and exhibited the highest ФPSII value compared with other bleached corals. These results highlight that the rare putatively thermally tolerant algae and coral species-specific algae may be important for understanding thermal bleaching of corals.
اظهر المزيد [+] اقل [-]Polybrominated diphenyl ethers and alternative halogenated flame retardants in mollusks from the Chinese Bohai Sea: Levels and interspecific differences
2019
Fu, Lingfang | Pei, Jie | Zhang, Yuyu | Cheng, Xiaogu | Long, Shenxing | Zeng, Lixi
Polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs) were measured in eleven mollusk species collected from the Chinese Bohai Sea. PBDEs and AHFRs were detected in all species, and their average total concentrations were in the range of 22.5–355 and 10.0–84.3 ng/g lipid weight, respectively. Decabromodiphenyl ether (BDE-209) and decabromodiphenylethane (DBDPE) were the dominant halogenated flame retardants (HFRs), contributing 22.5% to 73.6% and 3.1% to 38.3% of the total HFRs, respectively. The levels of PBDEs and AHFRs were moderate to high from a global perspective. Interspecific differences in the accumulation of PBDEs and AHFRs were characterized by heat map and cluster analysis. Composition profile differences were also observed, with higher proportions of AHFRs in gastropods than in bivalves. These species-specific differences in concentrations and profiles in mollusks were attributed to different species traits, including feeding habit, trophic level, and metabolic potential.
اظهر المزيد [+] اقل [-]Assessing the source of oil deposited in the surface sediment of Mormugao Port, Goa - A case study of MV Qing incident
2019
Suneel, V. | Saha, Mahua | Rathore, Chayanika | Sequeira, Jenica | Mohan, P.M Nikhil | Ray, Durbar | Veerasingam, S. | Rao, V Trinadha | Vethamony, P.
In June 2016, a cruise vessel was grounded in the Mormugao Port, resulting in unnoticed oil spill. The surface water and sediment samples were collected from the vicinity of the ship, and also an oil sample from the ship (OIL). These samples were subject to petroleum biomarker such as pentacyclic triterpenes (hopanes) and compound specific carbon isotopic (δ¹³C) analyses to assess the source of hydrocarbon pollution in the Mormugao Port. While no clear trend was observed in water samples, the bottom surface sediments did show an identical pattern of hopanes with the oil. The chemometric analyses of hopane Diagnostic Ratios (DRs) and δ¹³C ratios confirmed the ship oil as the source of oil pollution in sediments. Whereas the water is comparatively more dynamic than the sediment, the physical processes arising out of winds, waves, tides and currents might have dispersed the oil away from the grounded ship.
اظهر المزيد [+] اقل [-]Characterization of microplastics in environment by thermal gravimetric analysis coupled with Fourier transform infrared spectroscopy
2019
Yu, Jianping | Wang, Pingya | Ni, Fengli | Cizdziel, James | Wu, Dongxu | Zhao, Qiaoling | Zhou, Ying
As a global pollutant, microplastics have attracted attention from the public and researchers. However, the lack of standard and time-saving methods for analysis has become one of the bottlenecks in microplastics research. Here, we demonstrate TGA coupled to FTIR to identify and quantify certain microplastics in environment. Samples were pyrolyzed in TGA and the pyrolysis gases were analyzed by FTIR. Combining TGA and FTIR data adds discriminatory power as temperature profiles and absorption spectra differ among several common plastics. To quantify on a mass basis, we calibrated on characteristic IR peaks at temperatures of maximum weight loss for individual polymers. The method can distinguish PVC, PS and was validated by spiking samples with known quantities of microplastics. The result of field sample experiments showed that TGA-FTIR can be used to identify and quantify PVC and PS in bivalves, seawater and soil. And the method may be applicable to environmental samples.
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