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Результаты 1291-1300 из 4,291
Bioaccumulation of heavy metals and health risk assessment in three benthic bivalves along the coast of Laizhou Bay, China
2017
Liu, Jinhu | Cao, Liang | Dou, Shuozeng
This study investigated the tissue- and species-specific bioaccumulation of heavy metals (Cr, Cu, Hg, Zn, As, Cd, and Pb) in three benthic bivalves (the ark shell, Scapharca subcrenata; the surf clam, Mactra veneriformis; and the Manila clam, Ruditapes philippinarum) collected from the coast of Laizhou Bay in the Bohai Sea. The results demonstrated that the visceral masses of the bivalves tended to accumulate heavy metals more efficiently than their muscles. The capacities of the bivalves to bioaccumulate metals followed a similar order: Cd>Hg>Zn=As>Cu>Cr=Pb. The conditions of metal contamination in the bivalves tended to be worse along the eastern coast than in other regions. Overall, the Manila clam was more severely contaminated by heavy metals than the surf clam and ark shell. Judging by the hazard quotients (HQ) of the metals in the muscles of the bivalves, the greatest hazard risk to human health comes primarily from As.
Показать больше [+] Меньше [-]Talitrus saltator as a biomonitor: An assessment of trace element contamination on an urban coastline gradient
2017
Morrison, Liam | Bennion, Matthew | McGrory, Ellen | Hurley, William | Johnson, M.P.
This study reports the first ever application of the trace element pollution index (TEPI) along a coastal, urban gradient using trace element concentrations (Ti, Mn, Co, Cu, As, Mo, Ag, Cd, Pb, Cr, Fe, Zn and Se) in the amphipod crustacean Talitrus saltator. Samples were collected from 10 sites in Galway Bay (Ireland) and concentrations of Pb showed the greatest spatial variation, likely due to the proximity of some sites to a former landfill and busy harbour. The TEPI used alongside the quartile method allowed for the assigning of sites to contamination level categories. Mapping these class levels allowed for straightforward visualisation of trace element contamination along the urban gradient. In addition, this study presents trace elements levels in T. saltator form the Atlantic Coast of Europe for the first time and the concentrations observed were comparatively lower than previously reported for T. saltator from the Baltic and Mediterranean seas.
Показать больше [+] Меньше [-]Bioaccumulation of sediment-bound dichlorodiphenyltrichloroethane and heavy metals in benthic polychaete, Nereis succinea from a typical mariculture zone in South China
2017
Li, Huizhen | Wang, Fei | Yau, Ching
Bioaccumulation potential and associated ecological risk of sediment-bound DDT and its metabolites (DDXs) and heavy metals in Hailing Bay, a typical mariculture zone along the southern coast of China, were evaluated. The estuarine sediments were co-polluted by DDXs (120–4882ng/g dry wt.) and heavy metals (292–409mg/kg dry wt.). Both DDXs and metals in sediment were bioavailable to Nereis succinea, although the biota-sediment accumulation factors were less than 1 except for DDE. Significant transformation of DDT in organism was observed and DDE was the main metabolite. Ecological risk assessment showed that sediment-bound p,p′-DDT and p,p′-DDD frequently exhibited adverse effects on benthic community in the aquaculture zone, and heavy metals would cause moderate to considerable ecological risk, with Cd dominating the risk. The highest risk occurred in the shipyard area, indicating severe pollution and urgent need to control the source of DDT and heavy metals from aquafarming activities.Estuarine sediments in South China was co-polluted by DDT and its metabolites and heavy metals due to aquafarming activities, which resulted in bioaccumulation of the contaminants in benthic invertebrates and posed potential risk to species at higher trophic levels.
Показать больше [+] Меньше [-]Origin and distribution of hydrocarbons and organic matter in the surficial sediments of the Sfax-Kerkennah channel (Tunisia, Southern Mediterranean Sea)
2017
Zaghden, Hatem | Tedetti, Marc | Sayadi, Sami | Serbaji, Mohamed Moncef | Elleuch, Boubaker | Saliot, Alain
We investigated the origin and distribution of aliphatic and polycyclic aromatic hydrocarbons (AHs and PAHs) and organic matter (OM) in surficial sediments of the Sfax-Kerkennah channel in the Gulf of Gabès (Tunisia, Southern Mediterranean Sea). TOC, AH and PAH concentrations ranged 2.3–11.7%, 8–174μgg−1sed.dw and 175–10,769ngg−1sed.dw, respectively. The lowest concentrations were recorded in the channel (medium sand sediment) and the highest ones in the Sfax harbor (very fine sand sediment). AHs, PAHs and TOC were not correlated for most of the stations. TOC/N and δ13C values revealed a mixed origin of OM with both marine and terrestrial sources. Hydrocarbon molecular composition highlighted the dominance of petrogenic AHs and the presence of both petrogenic and pyrogenic PAHs, associated with petroleum products and combustion processes. This work underscores the complex distribution patterns and the multiple sources of OM and hydrocarbons in this highly anthropogenized coastal environment.
Показать больше [+] Меньше [-]Flow cytometry detection of planktonic cells with polycyclic aromatic hydrocarbons sorbed to cell surfaces
2017
Cerezo, Maria I. | Linden, Matthew | Agustí, Susana
Polycyclic aromatic hydrocarbons are very important components of oil pollution. These pollutants tend to sorb to cell surfaces, exerting toxic effects on organisms. Our study developed a flow cytometric method for the detection of PAHs sorbed to phytoplankton by exploiting their spectral characteristics. We discriminated between cells with PAHs from cells free of PAHs. Clear discrimination was observed with flow cytometer provided with 375 or 405nm lasers in addition to the standard 488nm laser necessary to identify phytoplankton. Using this method, we measured the relationship between the percentages of phytoplankton organisms with PAHs, with the decrease in the growth rate. Moreover, the development of this method could be extended to facilitate the study of PAHs impact on cell cultures from a large variety of organisms.
Показать больше [+] Меньше [-]Degradation of Pharmaceuticals and Personal Care Products by White-Rot Fungi—a Critical Review
2017
Asif, Muhammad B. | Hai, Faisal I. | Singh, Lakhveer | Price, William E. | Nghiem, Long D.
White-rot fungi (WRF) mediated treatment can offer an environmentally friendly platform for the removal of pharmaceuticals and personal care products (PPCPs) from wastewater. These PPCPs may have adverse impacts on aquatic organisms and even human and thus their removal during wastewater treatment is of significant interest to the water industry. Whole-cell WRF or their extracellular lignin modifying enzymes (LMEs) have been reported to efficiently degrade PPCPs that are persistent to conventional activated sludge process. WRF mediated treatment of PPCPs depends on a number of factors including physicochemical properties of PPCPs (e.g., hydrophobicity and chemical structure) and wastewater matrix (e.g., pH, temperature, and dissolved constituents), type of WRF species and their specific extracellular enzymes. This review critically analyzes the performance of whole-cell WRF and their LMEs for the removal of PPCPs; particularly, it offers insights into PPCP removal mechanisms (e.g., biosorption vs. biodegradation) and degradation pathways as well as the formation of intermediate byproducts.
Показать больше [+] Меньше [-]Distribution, sources and contamination assessment of heavy metals in surface sediments of the South Yellow Sea and northern part of the East China Sea
2017
Lu, Jian | Li, Anchun | Huang, Peng
Surface sediment samples collected from the South Yellow Sea and northern part of the East China Sea during spring and autumn, respectively, were analyzed for grain size, aluminum, and heavy metals (Cr, Ni, Cu, Zn, and Pb) to evaluate heavy metal levels and the contamination status. The results showed that all of the heavy metal concentrations met the standard criteria of the Chinese National Standard Criteria for Marine Sediment Quality. Both the EFs and a multivariate analysis (PCA) indicated that Cr, Ni, Cu, and Zn were mainly from natural contributions, while Pb was influenced by anthropogenic inputs, especially during autumn. The geoaccumulation index of Pb near the mouth of the Yangtze River suggested that the pollution degree in autumn was heavier than that in spring, which might be caused by the greater river discharge in summer and more heavy metal adsorption with finer grain sizes.
Показать больше [+] Меньше [-]The revealed preferences of Baltic Sea governments: Goals, policy instruments, and implementation of nutrient abatement measures
2017
Elofsson, Katarina | von Brömssen, Claudia
Nitrogen and phosphorus loads are considered a major reason for the eutrophication of the Baltic Sea. Until now, most of the abatement has been made at point sources while the implementation of policies for nonpoint sources has not led to equally large reductions in emissions. The purpose of this study is to investigate the determinants of how nutrient abatement measures are implemented by countries in the agricultural sector of the Baltic Sea region. We investigate how goal setting, policy instrument choice, and the level of implementation is determined by characteristics of the abatement measure as well as socio-economic characteristics of the country where it is implemented. Econometric analysis of a cross-sectional data set suggests that income, institutional capacity, and economies of scope in abatement and enforcement are important determinants of policies developed and their implementation.
Показать больше [+] Меньше [-]Thermal stress exposure, bleaching response, and mortality in the threatened coral Acropora palmata
2017
Williams, D.E. | Miller, M.W. | Bright, A.J. | Pausch, R.E. | Valdivia, A.
Demographic data for Elkhorn coral, Acropora palmata, and in situ water temperature data from seven upper Florida Keys (USA) reefs revealed three warm thermal stress events between 2010 and 2016. During a mild bleaching event in 2011, up to 59% of colonies bleached, but no mortality resulted. In both 2014 and 2015, severe and unprecedented bleaching was observed with up to 100% of colonies bleached. A. palmata live tissue cover declined by one-third following the 2014–2015 events. Colony mortality of mildly- and non-bleached colonies did not differ but increased significantly with more severe bleaching. Increased bleaching prevalence corresponded to maximum daily average water temperatures above 31.3°C. However, the cumulative days with daily average exceeding 31.0°C provided a better predictor of bleaching response. The bleaching response of surviving colonies in 2015 was not consistent with acclimatization as most individual colonies bleached at least as badly as in 2014.
Показать больше [+] Меньше [-]Performance and bacterial community structure of a 10-years old constructed mangrove wetland
2017
Tian, Tingting | Tam, Nora F.Y. | Zan, Qijie | Cheung, S.G. | Shin, Paul K.S. | Wong, Y.S. | Zhang, Li | Chen, Zhanghe
Constructed mangrove wetland has been used for wastewater treatment but its long-term performance has not been reported. One-year monitoring of a 10-years old horizontal subsurface-flow constructed mangrove wetland consisting of three belts, two with mangrove plants and one without, revealed that the system maintained high and stable removal percentages of organic matter and nutrients, and planted belts performed better than unplanted control. Substrates in belts planted with Aegiceras corniculatum or Kandelia obovata had higher abundance of ammonifiers, nitrifiers and denitrifiers but lower total heterotrophic bacteria than unplanted substrate. Denaturing gradient gel electrophoresis showed that microbial diversity in planted substrate was significantly lower than that in unplanted one. The bacteria in substrates, irrespective to belts, were phylogenetically related to Proteobacteria (most dominant), Acidobacteria, Firmicutes, Nitrospirae, Gemmatimonadetes, Chloroflexi and Cyanobacteria. The steady performance of this 10-year old constructed mangrove wetland was affected by the abundance and diversity of bacterial community in substrate.
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