خيارات البحث
النتائج 1901 - 1910 من 5,153
Bioaccumulation of trace metals in aquatic food web. A case study, Liaodong Bay, NE China النص الكامل
2018
Radomyski, Artur | Lei, Kai | Giubilato, Elisa | Critto, Andrea | Lin, Chunye | Marcomini, Antonio
The recently developed modelling tool MERLIN-Expo was applied to support the exposure assessment of an aquatic food web to trace metals in a coastal environment. The exposure scenario, built on the data from Daliao River estuary in the Liaodong Bay (Bohai Sea, China), affected by long-term and large-scale industrial activities as well as rapid urbanization in Liao River watershed, represents an interesting case-study for ecological exposure modelling due to the availability of local data on metal concentrations in water and sediment. The bioaccumulation of selected trace metals in aquatic organisms was modelled and compared with field data from local aquatic organisms. Both model results and experimental data demonstrated that As, Cd, Cu, Ni, Pb and Zn, out of examined metals, were accumulated most abundantly by invertebrates and less by higher trophic level species. The body parts of the sampled animals with the highest measured concentration of metals were predominantly muscles, intestine and liver and fish skin in the case of Cr.The Morris and extended Fourier Analysis (EFAST) were used to account for variability in selected parameters of the bioaccumulation model. Food assimilation efficiency and slopes and intercepts of two sub-models for calculating metal specific BCFs (BCFmetal-exposure concentration) and fish weight (Weightfish-Lengthfish) were identified as the most influential parameters on ecological exposure to selected metals.
اظهر المزيد [+] اقل [-]Identifying oil/marine snow associations in mesocosm simulations of the Deepwater Horizon oil spill event using solid-state 13C NMR spectroscopy النص الكامل
2018
Hatcher, Patrick G. | Obeid, Wassim | Wozniak, Andrew S. | Xu, Chen | Zhang, Saijin | Santschi, Peter H. | Quigg, Antonietta
The Deepwater Horizon oil spill stimulated the release of marine snow made up of dead/living plankton/bacteria and their exopolymeric polysaccharide substances (EPS), termed marine oil snow (MOS), promoting rapid removal of oil from the water column into sediments near the well site. Mesocosm simulations showed that Macondo surrogate oil readily associates with the marine snow. Quantitative solid-state 13C NMR readily distinguishes this oil from naturally formed marine snow and reveals that adding the dispersant Corexit enhances the amount of oil associated with the MOS, thus contributing to rapid removal from the water column. Solvent extraction of MOS removes the oil-derived compounds for analysis by one and two-dimensional GC/MS and evaluation of potential transformations they undergo when associated with the EPS. The results reveal that the oil associated with EPS is subjected to rapid transformation, in a matter of days, presumably by bacteria and fungi associated with EPS.
اظهر المزيد [+] اقل [-]Textural, surface and chemical properties of polyvinyl chloride particles degraded in a simulated environment النص الكامل
2018
Tang, Chih-Cheng | Chen, Huey-Ing | Brimblecombe, Peter | Lee, Chon-Lin
Virgin polyvinyl chloride (PVC) particles were exposed to heat, ultraviolet B (UVB) and solar radiation either in artificial seawater or in air for different periods of time. The surface and chemical properties of fresh and degraded particle surfaces were determined via image analysis using scanning electron micrographs, a Brunauer-Emmett-Teller (BET) specific surface area analyzer and infrared spectroscopy. Thermal and UVB degradation resulted in unique PVC morphologies. In addition, the increased presences of functional groups were evident as dehydrochlorination and oxidation during the degradation process, which altered the chemical properties of PVC. In contrast, under solar exposure with or without seawater, unevenness to the surface was noted that seems to originate from degradation of the PVC surface; in addition, no new functional groups were found. This suggests that the chemical properties of PVC are stable over extended periods in the marine environment.
اظهر المزيد [+] اقل [-]The use of anthropogenic marine debris as a nesting material by brown boobies (Sula leucogaster) النص الكامل
2018
Grant, Megan L. | Lavers, Jennifer L. | Stuckenbrock, Silke | Sharp, Paul B. | Bond, Alexander L.
Marine debris is pervasive worldwide, and affects biota negatively. We compared the characteristics of debris incorporated within brown booby (Sula leucogaster) nests throughout their pantropical distribution by assessing the type, colour and mass of debris items within nests and in beach transects at 18 sites, to determine if nests are indicators of the amount of debris in local marine environments. Debris was present in 14.4% of nests surveyed, with the proportion of nests with debris varying among sites (range: 0–100%). There was minimal overlap between the type or colour of debris found in nests and on adjacent beaches at individual sites. This suggests that brown boobies do not select debris uniformly across their distribution. We propose that the nests of brown boobies can be used as a sentinel of marine debris pollution of their local environment.
اظهر المزيد [+] اقل [-]Impacts of estuarine mixing on vertical dispersion of polycyclic aromatic hydrocarbons (PAHs) in a tide-dominated estuary النص الكامل
2018
Liu, Feng | Hu, Shuai | Guo, Xiaojuan | Niu, Lixia | Cai, Huayang | Yang, Qingshu
To examine the impacts of estuarine mixing on the dispersion of polycyclic aromatic hydrocarbons (PAHs), seasonal variations in the vertical distribution of dissolved PAHs in the Humen River mouth of the Pearl River Estuary, which is a tide-dominated estuary, were thoroughly examined. An analysis of the vertical distribution of the concentration, composition and sources of PAHs indicates enhanced mixing of PAHs in January relative to June, which is strongly related to seasonal variations in the magnitude of estuarine mixing. Furthermore, the vertical distribution of PAHs initially indicated an increase and then a decrease from the surface layer to the bottom layer. In general, estuarine mixing promotes the vertical dispersion of PAHs, causing a more even PAHs distribution, while salinity stratification can trap PAHs, resulting in higher PAHs concentrations. Our study indicates that salinity variability stimulates significant dynamic effects regarding the dispersion of PAHs within estuarine environments.
اظهر المزيد [+] اقل [-]Perennial occurrence of heterotrophic, indicator and pathogenic bacteria in the coastal Bay of Bengal (off Visakhapatnam) - Impact of physical and atmospheric processes النص الكامل
2018
Sudha Rani, P. | Sampath Kumar, G. | Mukherjee, J. | Srinivas, T.N.R. | Sarma, V.V.S.S.
In order to examine the health of the coastal waters off Visakhapatnam in terms of prevalence and abundance of heterotrophic (H), indicator and pathogenic (P) bacterial counts (BC) and influence of physical processes on them, time-series observations were conducted during January (winter), March (spring), July (summer) and October (post-monsoon). We noticed the impact of physical forces on substantial variations in abundance and distribution of the HBC, total coliforms, Enterococcus faecalis and Pseudomonas aeruginosa in the study region. Based on our results Escherichia coli and other PBC were not much influenced by the physical conditions. It has been noticed that the perennial existence of the high abundance of IBC and PBC above the standard limits during the entire study period leading to an alarming situation in the coastal waters off Visakhapatnam.
اظهر المزيد [+] اقل [-]Comparison of mesozooplankton mortality impacted by the cooling systems of two nuclear power plants at the northern Taiwan coast, southern East China Sea النص الكامل
2018
Lee, Pei-Wen | Tseng, Li-Chun | Hwang, Jiang-Shiou
The environmental impact caused by thermal discharge waters of power plants is of global concern since thermal discharge directly affects the environmental situation near power plants. The present study used the vital stain neutral red to identify live and dead zooplankton collected from stations at the intake and the outlet of two nuclear power plants (NPPs). Significantly higher mortalities occurred at the outlet station than at the intake station (p < 0.01) at both NPPs. The mortalities of most zooplankton taxa and all zooplankton assemblages were significantly positive correlated to differences of water temperature (ΔT) at NPP I (p < 0.05), whereas it was not significantly positive correlated with ΔT at NPP II (p > 0.05). The weight of organic matter of zooplankton fragments was higher at the outlet station than at the intake station at both NPPs, indicating the physical damage of zooplankton when passing the cooling system.
اظهر المزيد [+] اقل [-]Killing the goose with the golden eggs: Litter effects on scenic quality of the Caribbean coast of Colombia النص الكامل
2018
Rangel-Buitrago, Nelson | Williams, Allan | Anfuso, Giorgio
137 coastal sites located along the Caribbean coast of Colombia were surveyed to determine scenic quality, litter content, and typology. Scenic evaluation categorized sites into five classes. 26 appeared in Class I; 18 in Class II; 19 in Class III; 30 in class IV; and 44 in Class V. Beach type was categorized into urban (31), resort (18), rural (46), village (32) and remote (10). Litter gave 17 sites an “A” grade (excellent); 34 sites a “B” grade; 53 sites a “C” grade and 33 locations a “D” grade (poor). Almost all sites surveyed have a low scenic quality and also significant litter content. Currently, litter directly produces aesthetic problems along the study area, and improvements are necessary to favor coastal scenic quality. Stakeholders should make a significant effort to improve the scenic human parameters along the study area, litter removal and prevention being the most important.
اظهر المزيد [+] اقل [-]Baseline physio-chemical characteristics of Sydney estuary water under quiescent conditions النص الكامل
2018
Birch, G.F. | Lee, S.B.
The current study establishes baseline water quality properties for Sydney estuary, Australia for long periods of quiescence, which characterize the region. The study was undertaken in response to numerous requests for such data by researchers, government agencies and contractors.During quiescent periods, the range in Secchi depth transparency, turbidity, salinity and total suspended solid (TSS) values was 0.3–5.3 m, 18.6–0.1 NTU, 26.4–35.3 PSU and 8.3–1.0 mg/L in the upper and lower estuary, respectively. Baseline particulate metal concentrations were high, however TSS metal mass was greater during high rainfall.Tables and GIS-based maps allow baseline physio-chemical values to be extracted from the database for any location in Sydney estuary for quiescent conditions. Strong inter-parameter baseline relationships enable interpolation between water quality data. Baseline physio-chemical values were used to assess the impact of a high-precipitation event to demonstrate the utility of the new database.
اظهر المزيد [+] اقل [-]Characterization of polycyclic aromatic hydrocarbons (PAHs) in small craft harbour (SCH) sediments in Nova Scotia, Canada النص الكامل
2018
Davis, Emily | Walker, Tony R. | Adams, Michelle | Willis, Rob
Polycyclic aromatic hydrocarbons (PAHs) have been widely studied in sediments due to their ubiquity and persistence in aquatic environments and potential for impairment to biota. Small craft harbour (SCH) sediments in Nova Scotia (NS), Canada, have yet to be studied comprehensively. SCHs are essential to the fishing industry, which is important for the Canadian economy. This spatiotemporal characterization study evaluated thirty-one SCHs across NS between 2001 and 2017 by analyzing sediment reports (secondary data). Sediment PAH concentrations varied widely across all SCHs. Few SCHs exhibited sediment PAH concentrations likely to impair biota based on comparison to sediment quality guidelines. Sediments in the Gulf region of NS were least impacted by PAHs, while the Southwest region was most impacted. Distribution of individual PAHs in sediments follows global trends, with high molecular weight PAHs dominating samples.
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