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Résultats 611-620 de 2,459
An analysis of historical Mussel Watch Programme data from the west coast of the Cape Peninsula, Cape Town
2014
Sparks, Conrad | Odendaal, James | Snyman, Reinette
The concentrations of metals in the mussel Mytilus galloprovincialis (Lamarck, 1819) prevalent along the west coast of the Cape Peninsula, Cape Town are presented. The mussels were sampled during the routine “Mussel Watch Programme” (MWP) between 1985 and 2008. Levels of Cu, Cd, Pb, Zn, Hg, Fe and Mn at Cape Point, Hout Bay, Sea Point, Milnerton and Bloubergstrand were analysed for autumn and spring and showed consistent similar mean values for the five sites. There was a highly significant temporal (annual and seasonal) difference between all metals as well as a significant difference in metal concentrations between the five sites. The concentrations of Zn, Fe, Cd and Pb were higher than previous investigations and possibly indicative of anthropogenic sources of metals. The results provide a strong motivation to increase efforts in marine pollution research in the area.
Afficher plus [+] Moins [-]Modeling total maximum allocated loads for heavy metals in Jinzhou Bay, China
2014
Li, Keqiang | Shi, Xiaoyong | Bao, Xianwen | Ma, Qimin | Wang, Xiulin
With the recent development of society and economy in the cities of Huludao and Jinzhou, Liaoning Province, China, environment and ecosystem problems have become increasingly serious in Jinzhou Bay, China, because of the increasing amount of heavy metal pollutants being discharged. To solve these problems, a water quality model of heavy metals coupled with a 3D hydrodynamic model is constructed to estimate the environmental capacity (EC) and total maximum allocated loads (TMALs) for Zn and Cd of three river catchments in Jinzhou Bay. According to the model, the ECs for Zn and Cd are approximately 17 and 8tons per month, respectively, if the criterion obtained from HC5 values (fifth percentile of the SSD) is set as the control criterion (8.24μg/L for Zn and 3.83μg/L for Cd) in Jinzhou Bay, and the TMALs of the three river catchments are 4 and 1.7 tons per month.
Afficher plus [+] Moins [-]Polychlorinated biphenyl (PCB) concentrations and congener composition in masu salmon from Japan: A study of all 209 PCB congeners by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS)
2014
Matsumoto, Reiko | Tu, Nguyen Phuc Cam | Haruta, Shinsuke | Kawano, Masahide | Takeuchi, Ichirō
We collected two subspecies of masu salmon: Oncorhynchus masou masou from four localities (southern Sea of Japan northward to Hokkaido) and O. masou ishikawae from upstream from Ise Bay close to a heavy industrial area. All 209 PCB congeners were analyzed using HRGC/HRMS. PCA ordination of congener concentrations divided data into three groups: (i) ssp. masou from Hokkaido, (ii) ssp. masou from the other regions and (iii) ssp. ishikawae. The highest ∑ PCB concentration (40.39ng/wet wt) was in ssp. ishikawae followed by ssp. masou from southern waters; however the TEQdioxin-like PCBs was highest in ssp. masou from southern water (1.96pg-TEQdioxin-like PCBs/g wet wt.) due to the high proportion of congener #126 in its complement (#126 has the highest toxic equivalency factor among congeners). There is likely a contamination source offshore in the southern Sea of Japan and/or along the migratory route of ssp. masou.
Afficher plus [+] Moins [-]The influence of pearl oyster farming on reef fish abundance and diversity in Ahe, French Polynesia
2014
Cartier, Laurent E. | Carpenter, Kent E.
Many cultured pearl farms are located in areas of the Pacific that have thriving, highly diverse fish communities but the impacts of farming on these communities are poorly understood. We studied the effects of pearl oyster farming on shore fish abundance and diversity in the lagoon of Ahe, French Polynesia by adapting roving diver census methods to the coral reef bommies of the lagoon and compared 16 sites with high pearl farming impact to others with no direct impact. Pearl farming has a slightly positive effect on reef fish abundance (N) and no significant impact on fish diversity (H) or community composition. This is important when considering the ecological sustainability of pearl farming in French Polynesia and suggests that a potential synergy between pearl farms and marine conservation should be further explored.
Afficher plus [+] Moins [-]Heavy metals in particulate and colloidal matter from atmospheric deposition of urban Guangzhou, South China
2014
Huang, Wen | Duan, Dandan | Zhang, Yulong | Cheng, Hefa | Ran, Yong
Suspended particulate matter (SPM) and colloidal matter (COM) in annual dry and wet deposition samples in urban Guangzhou were for the first time collected, and their trace metals were investigated by using inductively coupled plasma mass spectrometry (ICP-MS). The deposition flux of SPM and of metal elements varied largely among the investigated seasons, and reached the maximum in spring. The correlation analysis indicated that significant correlations existed among some of the metal elements in the deposition samples. The enrichment factors (EF) of metals in COM in the deposition ranging from 79.66 to 130,000 were much higher than those of SPM ranging from 1.65 to 286.48, indicating the important role of COM. The factor analysis showed that emissions from street dust, non-ferrous metal production, and heavy fuel oil were major sources of the trace metals. Positive matrix factorization (PMF) model was used to quantitatively estimate anthropogenic source.
Afficher plus [+] Moins [-]Impact of total organic carbon (in sediments) and dissolved organic carbon (in overlying water column) on Hg sequestration by coastal sediments from the central east coast of India
2014
Chakraborty, Parthasarathi | Sharma, Brijmohan | Raghunath Babu, P.V. | Yao, Koffi Marcellin | Jaychandran, Saranya
Total organic carbon (TOC) (in sediment) and dissolved organic matter (DOM) (in water column) play important roles in controlling the mercury sequestration process by the sediments from the central east coast of India. This toxic metal prefers to associate with finer size particles (silt and clay) of sediments. Increasing concentrations of DOM in overlying water column may increase complexation/reduction processes of Hg2+ within the water column and decrease the process of Hg sequestration by sediments. However, high concentrations of DOM in water column may increase Hg sequestration process by sediments.
Afficher plus [+] Moins [-]Description of a Multimetric Phytoplankton Index (MPI) for the assessment of transitional waters
2014
Facca, Chiara | Bernardi Aubry, Fabrizio | Socal, Giorgio | Ponis, Emanuele | Acri, Francesco | Bianchi, Franco | Giovanardi, Franco | Sfriso, Adriano
A Multimetric Phytoplankton Index (MPI) is proposed to support management policies for the assessment of transitional ecosystems and the implementation of the European Water Framework Directive. The MPI incorporates Hulburt’s dominance index, bloom frequency and Menhinick’s diversity index, calculated on the basis of phytoplankton species composition.Chlorophyll a concentrations were also included, to provide biomass data and to guarantee continuity and comparison with past evaluations. The MPI was calculated by averaging the ratios of the resulting values of each metric to those of a reference site characterised by low anthropogenic impact.The MPI was set up using data from over a 10-year period in several stations in Venice Lagoon (North-western Adriatic region), a highly valuable and heterogeneous transitional environment, subject to significant anthropogenic pressures. The dataset included physico-chemical data, nutrient and contaminant concentrations. Statistical analyses allowed us to gauge the MPI’s responses to anthropogenic pressures and to verify its reliability.
Afficher plus [+] Moins [-]Distributions of polycyclic aromatic hydrocarbons and alkylated polycyclic aromatic hydrocarbons in Osaka Bay, Japan
2014
Miki, Shizuho | Uno, Seiichi | Ito, Kazuki | Koyama, Jiro | Tanaka, Hiroyuki
Contaminations in sediments by polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs were investigated at 44 sites in Osaka Bay, Japan. Concentrations of total PAHs and alkylated PAHs were in the range 6.40–7800ng/g dry weights and 13.7–1700ng/g dry weights, respectively. The PAH concentrations tended to be higher along the shoreline in the vicinities of big ports, industrialized areas, and densely populated regions such as the cities of Osaka and Kobe. The major sources appeared to be pyrogenic or both pyrogenic and petrogenic at most of the sites. PAH concentrations were remarkably high at a site near Kobe, where the concentrations of dibenzo(a,h)anthracene and benzo(g,h,i)perylene exceeded the effects-range-medium concentration and eight PAHs were above the corresponding effects-range-low concentrations. Those PAHs may have been derived from the great fire associated with the large earthquake in 1995.
Afficher plus [+] Moins [-]BIOB: A mathematical model for the biodegradation of low solubility hydrocarbons
2014
Geng, Xiaolong | Boufadel, Michel C. | Personna, Yves R. | Lee, Ken | Tsao, David | Demicco, Erik D.
Modeling oil biodegradation is an important step in predicting the long term fate of oil on beaches. Unfortunately, existing models do not account mechanistically for environmental factors, such as pore water nutrient concentration, affecting oil biodegradation, rather in an empirical way. We present herein a numerical model, BIOB, to simulate the biodegradation of insoluble attached hydrocarbon. The model was used to simulate an experimental oil spill on a sand beach. The biodegradation kinetic parameters were estimated by fitting the model to the experimental data of alkanes and aromatics. It was found that parameter values are comparable to their counterparts for the biodegradation of dissolved organic matter. The biodegradation of aromatics was highly affected by the decay of aromatic biomass, probably due to its low growth rate. Numerical simulations revealed that the biodegradation rate increases by 3–4 folds when the nutrient concentration is increased from 0.2 to 2.0mgN/L.
Afficher plus [+] Moins [-]Amount and type of derelict gear from the declining black pearl oyster aquaculture in Ahe atoll lagoon, French Polynesia
2014
Andréfouët, Serge | Thomas, Yoann | Lo, Cedrik
Pearl oyster aquaculture is a major activity in French Polynesia atoll lagoons. After the economic decline that characterized the last decade, concerns recently rose about discarded installations and materials that supported aquaculture practices and by facilities abandoned after they had to close their activities. In May 2013, a first inventory of the type and amount of pearl farms derelict gear (PFDG) was achieved on 47 sites in Ahe lagoon. Surveys were conducted within and outside the boundaries of aquaculture concessions. Twenty types of PFDG littered the lagoon floor and the water column. The most impacted areas were near abandoned grafting houses with up to nine types of PFDG. Forty-five percent of the sites were impacted, including outside concessions. While management authorities are fully aware of the problem, this first assessment is a wake-up call to stimulate the cleaning of lagoons, enhance awareness among farmers, and identify potential ecological consequences on lagoon ecosystems.
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