خيارات البحث
النتائج 1491 - 1500 من 3,991
Marine litter as a vector for non-native species: What we need to know
2016
Rech, Sabine | Borrell, Yaisel | García Vázquez, Eva
Plastic debris and other floating materials endanger severely marine ecosystems. When they carry attached biota they can be a cause of biological invasions whose extent and intensity is not known yet. This article focuses on knowledge gaps and research priorities needed for, first, understanding and then preventing dispersal of alien invasive species attached to marine litter.
اظهر المزيد [+] اقل [-]Seasonal distribution of metals in vertical and horizontal profiles of sheltered and exposed beaches on Polish coast
2016
Bigus, Katarzyna | Astel, Aleksander | Niedzielski, Przemysław
The distribution of alkali and heavy metals in coastal sediments of three Polish beaches was assessed. In all locations there are sandy beaches of different characteristics according to the anthropogenic impact and degree of sheltering. Core sediments collected in Czołpino and Ustka were characterized by the highest concentration of Cd, Ag, Ba, and Al, Cu, Cr, Bi, Na, respectively. Among the alkaline metals core sediments were the most abundant with Ca, Bi, Mg and Na, presenting almost stable decreasing order in all beaches. The majority of dredge material collected can be classified as light or trace contaminated by Cr, Cu, Zn, Cd and Hg. An abundance of mineralogical components in core sediments in Ustka increases in Summer and Autumn, while in Puck is stable throughout the year. The content of studied metals in core sediments collected in three Polish beaches changes both in the vertical and horizontal profiles of the beach.
اظهر المزيد [+] اقل [-]Effects of the urban environmental conditions on the physiology of lichen and moss
2016
Sujetovienė, Gintarė | Galinytė, Vilma
The lichen Evernia prunastri (L.) Ach. and the moss Ptilium crista-castrensis (Hedw.) DeNot were exposed in three different urban sites along with the different pollution loads in order to evaluate the environmental quality. Physiological changes after the exposition were assessed by evaluating the content of photosynthetic pigments, chlorophyll fluorescence, membrane lipid peroxidation and integrity of cell membranes. The differences in response of fluorescence, chlorophylls contents and injuries of cell membranes were observed between the two species and between the sites. E. prunastri showed a great capacity to sustain the photosynthesis processes in the urban environment, while this capacity was very low in the transplanted moss P. crista-castrensis. The levels of malondialdehyde (MDA) indicated a significantly higher oxidative stress in the transplants at urban and residential sites. The integrity of cell membranes in moss samples was also more damaged than in lichen.
اظهر المزيد [+] اقل [-]Chemical dispersants: Oil biodegradation friend or foe?
2016
Rahsepar, Shokouh | Smit, Martijn P.J. | Murk, Albertinka J. | Rijnaarts, Huub H.M. | Langenhoff, Alette A.M.
Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil biodegradation by alkane and/or aromatic degrading bacterial culture in artificial seawater at different dispersant to oil ratios (DORs). Our results show that dispersant addition did not enhance oil biodegradation. At DOR 1:20, biodegradation was inhibited, especially when only the alkane degrading culture was present. With a combination of cultures, this inhibition was overcome after 10days. This indicates that initial inhibition of oil biodegradation can be overcome when different bacteria are present in the environment. We conclude that the observed inhibition is related to the enhanced dissolution of aromatic compounds into the water, inhibiting the alkane degrading bacteria.
اظهر المزيد [+] اقل [-]Decadal increase in the number of recreational users is concentrated in no-take marine reserves
2016
Gonson, Charles | Pelletier, Dominique | Gamp, Elodie | Preuss, Bastien | Jollit, Isabelle | Ferraris, Jocelyne
In coastal areas, demographic increase is likely to result in greater numbers of recreational users, with potential consequences on marine biodiversity. These effects may also occur within Marine Protected Areas (MPAs), which are popular with recreational users. Our analysis builds on data collected over a ten-year period during three year-round surveys to appraise changes in recreational boating activities in coral ecosystems. Results show that the number of boaters has greatly increased, particularly so within MPAs during weekends and the warm season, when peaks in boat numbers have become more frequent. We also observed that the number of anchored boats has increased over the period. These changes may be resulting in biophysical impacts that could be detrimental to conservation objectives in MPAs. This steady increase over time may cause changes in the spatial and temporal distribution of users and in their practices, thus highlighting the importance of monitoring recreational activities.
اظهر المزيد [+] اقل [-]Study of chemical species associated with fine particles and their secondary particle formation at semi-arid region of India
2016
Satsangi, P.G. | Pipal, A.S. | Budhavant, K.B. | Rao, P.S.P. | Taneja, A.
The fine particles (PM2.5) were collected for 24 h from Agra atmosphere and chemically characterized during the one year study period. The average concentration of PM2.5 was 90.21 ± 20.62 μg m−3 which is higher than NAAQS and WHO annual standards and their seasonal trend was winter > summer > monsoon. Ionic study indicates that cations were dominant in comparison to anions. Seasonally, F−, Ca2+ and Mg2+ were higher during summer period and Cl−, NO3−, NH4+ and K+ were higher during monsoon period while SO42− was higher during winter season. The ratios Ca2+/Na+, Mg2+/Na+ and SO42−/Na+ were higher, while Cl−/Na ratio was lower than sea water ratio indicating the incorporation of non marine constituents in aerosols. The observed Cl−/Na+ (average 0.71) deviate considerable from the Sea water ratio suggesting either a fractionation of Cl− or enrichment of Na+ as there was significant deviation from marine sources. Linear correlation was observable between nss-Ca2+ and nss-Mg2+ with HCO3− throughout the annual seasonal cycle (HCO3−: Ca = 0.59, HCO3−: Mg2+ = 0.53) suggesting the origination of these species from soil dust. The calculated conversion ratio of ‘S’ (CRS) was lower than ‘N’ (CRN) which suggests that the secondary formation of NO3− aerosol from NO2 was more predominant than SO42−. Trajectory analysis indicates that long range transportation also contributes to PM2.5 mass over the measurement site.
اظهر المزيد [+] اقل [-]Accumulation and temporal changes of PCDD/Fs and dioxin-like PCBs in finless porpoises (Neophocaena asiaeorientalis) from Korean coastal waters: Tracking the effectiveness of regulation
2016
Jeong, Yunsun | Kim, Sang-jo | Shin, Kyung-Hoon | Hwang, Seung Yong | An, Yong-Rock | Moon, Hyo-Bang
Temporal trend studies are useful to evaluate the effectiveness of regulations on local pollutants. The emission of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (PCBs) has been regulated by the Korean government in accordance with the Stockholm Convention. The accumulation and temporal trends of PCDD/Fs and dioxin-like PCBs were investigated in finless porpoises (Neophocaena asiaeorientalis) collected in Korean waters. Median concentrations of PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs were 1.0, 1.1, 0.1, and 1.8pgTEQ/g lipid weight, respectively, which were lower than threshold values for marine mammals. Age- and sex-dependent accumulation patterns were found for PCDFs and DL-PCBs. Temporal trends in finless porpoises collected between 2003 and 2010 showed significant reduction rates of 57%, 54%, 69%, and 60% for PCDDs, PCDFs, non-ortho PCBs, and mono-ortho PCBs, respectively. Our results suggest that the regulations on dioxin-like contaminants have been effective for marine mammals in Korea.
اظهر المزيد [+] اقل [-]A- DROP: A predictive model for the formation of oil particle aggregates (OPAs)
2016
Zhao, Lin | Boufadel, Michel C. | Geng, Xiaolong | Lee, Kenneth | King, Thomas | Robinson, Brian | Fitzpatrick, Faith
Oil–particle interactions play a major role in removal of free oil from the water column. We present a new conceptual–numerical model, A-DROP, to predict oil amount trapped in oil–particle aggregates. A new conceptual formulation of oil–particle coagulation efficiency is introduced to account for the effects of oil stabilization by particles, particle hydrophobicity, and oil–particle size ratio on OPA formation. A-DROP was able to closely reproduce the oil trapping efficiency reported in experimental studies. The model was then used to simulate the OPA formation in a typical nearshore environment. Modeling results indicate that the increase of particle concentration in the swash zone would speed up the oil–particle interaction process; but the oil amount trapped in OPAs did not correspond to the increase of particle concentration. The developed A-DROP model could become an important tool in understanding the natural removal of oil and developing oil spill countermeasures by means of oil–particle aggregation.
اظهر المزيد [+] اقل [-]The occurrence of PAHs and faecal sterols in Dublin Bay and their influence on sedimentary microbial communities
2016
Murphy, Brian T. | O'Reilly, Shane S. | Monteys, Xavier | Reid, Barry F. | Szpak, Michal T. | McCaul, Margaret V. | Jordan, Sean F. | Allen, Christopher C.R. | Kelleher, Brian P.
The source, concentration, and potential impact of sewage discharge and incomplete organic matter (OM) combustion on sedimentary microbial populations were assessed in Dublin Bay, Ireland. Polycyclic aromatic hydrocarbons (PAHs) and faecal steroids were investigated in 30 surface sediment stations in the bay. Phospholipid fatty acid (PLFA) content at each station was used to identify and quantify the broad microbial groups present and the impact of particle size, total organic carbon (%TOC), total hydrogen (%H) and total nitrogen (%N) was also considered. Faecal sterols were found to be highest in areas with historical point sources of sewage discharge. PAH distribution was more strongly associated with areas of deposition containing high %silt and %clay content, suggesting that PAHs are from diffuse sources such as rainwater run-off and atmospheric deposition. The PAHs ranged from 12 to 3072ng/g, with 10 stations exceeding the suggested effect range low (ERL) for PAHs in marine sediments. PAH isomer pair ratios and sterol ratios were used to determine the source and extent of pollution. PLFAs were not impacted by sediment type or water depth but were strongly correlated to, and influenced by PAH and sewage levels. Certain biomarkers such as 10Me16:0, i17:0 and a17:0 were closely associated with PAH polluted sediments, while 16:1ω9, 16:1ω7c, Cy17:0, 18:1ω6, i16:0 and 15:0 all have strong positive correlations with faecal sterols. Overall, the results show that sedimentary microbial communities are impacted by anthropogenic pollution.
اظهر المزيد [+] اقل [-]Is the way an oil spill response is reported in the media important for the final perception of the clean-up?
2016
Chilvers, B.L. | Finlayson, G. | Ashwell, D. | Low, S.I. | Morgan, K.J. | Pearson, H.E.
This research investigates the media coverage during the C/V Rena grounding in New Zealand (NZ), in 2011, to analyze if information reported in printed media is important for the final perception of the overall oil spill response. We took all articles available from NZ's largest circulated newspaper and the regional newspaper closest to the incident and analyzed the themes within each article; the article's tone (positive, neutral or negative); the time of the report relative to incident events and any differences between the regional and national papers. This analysis indicates that oil spills are reported and perceived as inherently negative incidents. However, along with coordinating an effective spill response, fast, factual and frequent media releases and increased effect in media liaison in areas of response with high public intrinsic value such as oiled wildlife response can significantly influence tone of media coverage and likely overall public perception.
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