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Результаты 741-750 из 3,243
Assessment of metal contamination in coastal sediments of the Maluan Bay (China) using geochemical indices and multivariate statistical approaches
2015
Wang, Zaosheng | Wang, Yushao | Chen, Liuqin | Yan, Changzhou | Yan, Yijun | Chi, Qiaoqiao
Total concentrations and chemical forms of heavy metals in surface sediments of Maluan Bay were determined and multiple geochemical indices and guidelines were applied to assess potential contamination and environmental risks. Metal concentrations exhibited significant spatial variation and the speciation of Cr was presented dominantly in the residual fraction, while Cd was found mostly in the non-residual fraction and thus of high potential bioavailability. Cluster analysis separated four subgroups of sampling sites with different levels of contamination. Further, a multivariate method offered the specific interpretation of possible contaminant sources and/or pathways. Factor scores characterized the sampling locations and elucidated the pollution status, pointing out the impact of multiple “hidden hotspots” of contaminants and providing further evidence of the existence of clear pollution-risk gradients in lagoon areas. The study supports the integrative approach as powerful tool to diagnose the pollution status scientifically for management decisions in coastal sediment of complex environment.
Показать больше [+] Меньше [-]Trace elements in eggs of common eiders (Somateria mollissima) breeding in Nova Scotia, Canada
2015
Pratte, Isabeau | Tomlik, Molly D. | Betsch, Taylor A. | Braune, Birgit M. | Milton, G Randy | Mallory, Mark L.
We provide the first report on trace element concentrations in eggs of common eiders (Somateria mollissima), a coastal benthic foraging sea duck, from Nova Scotia, Canada, and compare those to known values from this species elsewhere. Most trace elements of toxicological concern (Hg, Se, Cd, Cu, Zn) were lower in eider eggs from Nova Scotia than from eider eggs collected farther north in Canada, although As was elevated. Our data provide strong support for a pattern of increasing Hg at higher latitudes for this species.
Показать больше [+] Меньше [-]Cetacean noise criteria revisited in the light of proposed exposure limits for harbour porpoises
2015
Tougaard, Jakob | Wright, Andrew J. | Madsen, Peter T.
The impact of underwater noise on marine life calls for identification of exposure criteria to inform mitigation. Here we review recent experimental evidence with focus on the high-frequency cetaceans and discuss scientifically-based initial exposure criteria. A range of new TTS experiments suggest that harbour and finless porpoises are more sensitive to sound than expected from extrapolations based on results from bottlenose dolphins. Furthermore, the results from TTS experiments and field studies of behavioural reactions to noise, suggest that response thresholds and TTS critically depend on stimulus frequency. Sound exposure levels for pure tones that induce TTS are reasonably consistent at about 100dB above the hearing threshold for pure tones and sound pressure thresholds for avoidance reactions are in the range of 40–50dB above the hearing threshold. We propose that frequency weighting with a filter function approximating the inversed audiogram might be appropriate when assessing impact.
Показать больше [+] Меньше [-]Meteorological driven changes on air quality over Portugal: a KZ filter application
2015
Sá, Elisa | Tchepel, Oxana | Carvalho, Anabela | Borrego, C.
The Kolmogorov–Zurbenko (KZ) filter method is a tool to improve air quality management, since it determines meteorological effects on air quality concentrations and separates out those effects in order to examine underlying trends. Air quality in Portugal is exceeding the legislated particulate matter (PM10), nitrogen oxides (NO2) and ozone (O3) levels; accordingly, measures to reduce pollutant emissions have been designed. The primary objective of this work is to investigate the influence of meteorology on O3, NO2 and PM10 levels and the long-term air quality trends. Air quality and meteorological datasets were explored for the period 2002–2012 through the decomposition of time-series using the Kolmogorov–Zurbenko (KZ) filter. To determine the best meteorological predictors for the air quality data, a stepwise regression analysis of the filtered time-series was applied. The KZ filter application revealed that the short-term component has the highest contribution to the total variance of the original air quality data (≈64%–PM10; ≈52%–O3; ≈54%–NO2) followed by the seasonal component. The long-term component exhibits the influence of the emission control regulations implemented in each study region. The statistical analysis of the air quality and the meteorological data indicated that O3 has a statistically significant relationship with temperature in most of the components. The results also indicate that emission control strategies are primary regulators for NO2 and PM10 levels. Therefore, to establish an accurate strategy to improve air quality further, it will be essential to include meteorological effects. This study highlights that the KZ filter is a useful tool to support the design and implementation of adequate air quality strategies and for the investigation of the interactions between the emissions, the meteorological conditions and the air quality levels, to improve air quality management in these two urban areas.
Показать больше [+] Меньше [-]Magnetic properties of sediments in cores from the Mandovi estuary, western India: Inferences on provenance and pollution
2015
Prajith, A. | Rao, V Purnachandra | Kessarkar, Pratima M.
Magnetic properties of sediments were investigated in 7 gravity cores recovered along a transect of the Mandovi estuary, western India to understand their provenance and pollution. The maximum magnetic susceptibility of sediments was at least 6 times higher in the upper/middle estuary than in lower estuary/bay. The χfd% and χARM/SIRM of sediments indicated coarse, multi-domain and pseudo-single domain magnetic grains, resembling ore material in the upper/middle estuary and coarse stable single domain (SSD) to fine SSD grains in the lower estuary/bay. Mineralogy parameters indicated hematite and goethite-dominated sediments in the upper/middle estuary and magnetite-dominated sediments in the lower estuary/bay. Two sediment types were discernible because of deposition of abundant ore material in the upper/middle estuary and detrital sediment in the lower estuary/bay. The enrichment factor and Index of geo-accumulation of metals indicated significant to strong pollution with respect to Fe and Mn in sediments from the upper/middle estuary.
Показать больше [+] Меньше [-]Assessment of organotin and tin-free antifouling paints contamination in the Korean coastal area
2015
Lee, Mi-Ri-Nae | Kim, Ŭn-jung | Lee, In-Seok | Choi, Minkyu | Oh, Jeong-Eun
Twelve organotins (methyl-, octyl-, butyl-, and phenyl-tin), and eight tin-free antifouling paints and their degradation products were measured in marine sediments from the Korean coastal area, and Busan and Ulsan bays, the largest harbor area in Korea. The total concentration of tin-free antifouling paints was two- to threefold higher than the total concentration of organotins. Principal component analysis was used to identify sites with relatively high levels of contamination in the inner bay area of Busan and Ulsan bays, which were separated from the coastal area. In Busan and Ulsan bays, chlorothalonil and DMSA were more dominant than in the coastal area. However, Sea-Nine 211 and total diurons, including their degradation products, were generally dominant in the Korean coastal area. The concentrations of tin and tin-free compounds were significantly different between the east and west coasts.
Показать больше [+] Меньше [-]Polycyclic aromatic hydrocarbons in surface sediment from Yangpu Bay, China: Distribution, sources and risk assessment
2015
Li, Ping | Diao, Xiaoping | Zhang, Yu | Xie, Yanli | Yang, Fei | Zhou, Hailong | Han, Qian | Wang, Fuqiang | Cheng, Huamin | Wang, Haihua
The study investigated the occurrence of polycyclic aromatic hydrocarbons (PAHs) in the surface sediment from eleven sites in Yangpu Bay, China in December 2013 (winter) and July 2014 (summer). The 16 US EPA priority PAHs were found in the range of 1583.2–5701.7ng/g dry weights with an average of 3134.7±1241.3ng/g in winter and ranged from 2161.8 to 4527.2ng/g with an average of 3016.6±748.0ng/g in summer, respectively. The concentrations of the PAHs tended to be relatively high in comparison with other areas from the literatures. The identification using molecular indices analysis indicated that the PAHs originated mainly from pyrogenic and petrogenic sources in most of the sites. According to principle component analysis–multiple linear regression (PCA/MLR) for their source apportionment, the main sources of PAHs were vehicle emissions, petroleum products and biomass combustion. The risk assessment using international sediments quality guidelines and sediments quality criteria indicated that several PAHs, such as Nap, Flu, Phe, Ace, Acy and BghiP in most of the sites would potentially affect organisms in Yangpu Bay.
Показать больше [+] Меньше [-]Modelling the fate and transport of faecal bacteria in estuarine and coastal waters
2015
Gao, Guanghai | Falconer, R. A. | Lin, Binliang
This paper details a numerical model developed to predict the fate and transport of faecal bacteria in receiving surface waters. The model was first validated by comparing model predicted faecal bacteria concentrations with available field measurements. The model simulations agreed well with the observation data. After calibration, the model was applied to investigate the effects of different parameters, including: tidal processes, river discharges from the upstream boundaries and bacteria inputs from the upstream boundaries, wastewater treatment works (WwTWs), rivers and combined sewer overflows (CSO), on the concentrations of faecal bacteria in the Ribble Estuary. The results revealed that the tide and upstream boundary bacteria inputs were the primary factors controlling the distribution of faecal bacteria. The bacteria inputs from the WwTWs in the model domain were generally found not to have a significant impact on distribution of faecal bacteria in the estuary.
Показать больше [+] Меньше [-]Seasonal effect on biomarkers of exposure to petroleum hydrocarbons in fish from Kuwait's marine area
2015
Beg, M.U. | Al-Subiai, S.N. | Al-Jandal, N. | Butt, S.A. | Beg, K.R. | Al-Husaini, M.
The aquatic biota of the Arabian Gulf deals with exposure to chronic oil pollution, several constituents of which cause induction of Cytochrome P450 1A that serves as a biomarker of AhR ligand exposure. In this study, fluorescent aromatic compounds (FACs) in bile and 7-ethoxyresorufin-o-deethylase (EROD) catalytic activity were determined as a measure of exposure biomarkers in two fish species, yellow fin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) captured from Kuwait Bay and outside the Bay area. FACs in fish bile determined by using fixed-wavelength fluorescence (FF) showed high fluorescence ratios between FF290/335 and FF380/430 indicating predominant exposure to low molecular weight, naphthalene-rich petroleum products (375±91.0pgml−1). Exposures to benzo(a)pyrene-type high-molecular weight polycyclic aromatic hydrocarbons (PAHs) originating from burnt fuel were also present in appreciable concentration in the bile. The ratio of petrogenic to pyrogenic hydrocarbon was twofold higher in winter compared to summer months in both species. Seasonal effect on EROD was significant in tonguesole in Auha site (P<0.05); whereas seabream resisted seasonal change. Tonguesole is considered to be a suitable bioindicator of oil pollution in Kuwait Bay area.
Показать больше [+] Меньше [-]What did we learn from PEGASEAS forum “Science and Governance of the Channel Marine Ecosystem”?
2015
Evariste, Emmanuelle | Claquin, Pascal | Robin, Jean-Paul | Auber, Arnaud | McQuatters-Gollop, Abigail | Fletcher, Stephen | Glegg, Gillian | Dauvin, Jean-Claude
As one of the busiest marine ecosystems in the world, the English Channel is subjected to strong pressures due to the human activities occurring within it. Effective governance is required to improve the combined management of different activities and so secure the benefits provided by the Channel ecosystem. In July 2014, a Cross-Channel Forum, entitled “Science and Governance of the Channel Marine Ecosystem”, was held in Caen (France) as part of the INTERREG project “Promoting Effective Governance of the Channel Ecosystem” (PEGASEAS). Here we use outputs from the Forum as a framework for providing Channel-specific advice and recommendations on marine governance themes, including the identification of knowledge gaps, which may form the foundation of future projects for the next INTERREG project call (2015–2020).
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