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Результаты 651-660 из 1,506
Geochemistry of the northern Cyprus (NE Mediterranean) shelf sediments: Implications for anthropogenic and lithogenic impact
2012
Duman, Muhammet | Kucuksezgin, Filiz | Atalar, Muge | Akcali, Baris
The concentrations of heavy metals and organic carbon in sediment were determined to evaluate spatial distributions from the three different regions of Cilician basin (Eastern Mediterranean) in 2011. The ranges of Cu, Pb, Zn, Ni, Co, Mn, Cr, As, Fe and organic carbon contents of sediments from the study area were 1.6–74, 1.6–9.2, 5.0–78, 6.6–114, 1.6–17, 141–1241, 9.0–46, 3.3–55.4, 1800–84400mgkg⁻¹ and 0.99–1.66%, respectively. The concentrations of Pb, Zn, Co, Cr, Al were lower than those average crustal values, which indicated that there were no major sources of pollution for these elements. The results showed that the sediments of northern, eastern and western shelf were polluted with As, Ni and Mn, As and Cu, Fe, respectively. The contamination factor of Cu in the western and As were found to be of moderate contamination in the eastern and northern parts of the study area. Metal levels were evaluated in sediments in accordance with the numerical SQG of the USEPA.
Показать больше [+] Меньше [-]Sewage organic markers in surface sediments around the Brazilian Antarctic station: Results from the 2009/10 austral summer and historical tendencies
2012
Martins, César C. | Aguiar, Sabrina Nart | Bícego, Márcia C. | Montone, Rosalinda C.
The discharge of sewage into the Antarctic marine environments by scientific stations has resulted in local changes in these pristine sites. To assess the distribution and concentration of sewage indicators from the Brazilian Antarctic station, sediments were sampled during the 2009/10 austral summer at four points (water depth of 20 and 60m). Concentrations of faecal sterols and linear alkylbenzenes (LABs) ranged from <0.01 to 0.17μgg⁻¹ and <1.0 to 46.5ngg⁻¹ dry weight, respectively. Maximum concentration of faecal sterols was similar to the value previously calculated as the background level for this area (0.19μgg⁻¹), and it is lower than the concentration observed in previous studies (1997–2008), whereas the LABs concentrations remained practically constant (35ngg⁻¹). Despite the low concentrations of sewage markers, the permanent human activities in the region require monitoring programs to determine continuing trends and prevent the increase of anthropogenic impacts.
Показать больше [+] Меньше [-]Field studies using fish biomarkers – How many fish are enough?
2012
Gagnon, M.M. | Hodson, P.V.
Significant efforts are invested in field studies using fish, and it is important to optimize the number of organisms collected to evaluate the possible impacts of contamination. This paper provides ecotoxicologists with the approximate numbers of fish needed to identify statistically significant differences among samples using physiological indices and biochemical markers of fish health. The numbers of fish to collect are reported for ethoxyresorufin-o-deethylase (EROD); ethoxycoumarin-o-deethylase (ECOD), serum sorbitol dehydrogenase (sSDH), stress proteins, gonadosomatic index, liver somatic index, condition factor, and biliary metabolites of polycyclic aromatic hydrocarbons. The number of fish to collect was as few as four for ECOD activity (with a power of 80%), but as high as 106 for CF (with a power of 95%). Achieving statistical significance between sites does not help in the interpretation of the biological significance of a parameter, but well-planned field samplings will maximize the chances of correctly identifying areas of concern.
Показать больше [+] Меньше [-]Comparison of recreational health risks associated with surfing and swimming in dry weather and post-storm conditions at Southern California beaches using quantitative microbial risk assessment (QMRA)
2012
Tseng, Linda Y. | Jiang, Sunny C.
Southern California is an increasingly urbanized hotspot for surfing, thus it is of great interest to assess the human illness risks associated with this popular ocean recreational water sport from exposure to fecal bacteria contaminated coastal waters. Quantitative microbial risk assessments were applied to eight popular Southern California beaches using readily available enterococcus and fecal coliform data and dose-response models to compare health risks associated with surfing during dry weather and storm conditions. The results showed that the level of gastrointestinal illness risks from surfing post-storm events was elevated, with the probability of exceeding the US EPA health risk guideline up to 28% of the time. The surfing risk was also elevated in comparison with swimming at the same beach due to ingestion of greater volume of water. The study suggests that refinement of dose-response model, improving monitoring practice and better surfer behavior surveillance will improve the risk estimation.
Показать больше [+] Меньше [-]Uncertainty analysis along the ecological quality status of water bodies: The response of the Posidonia oceanica multivariate index (POMI) in three Mediterranean regions
2012
Mascaró, Oriol | Bennett, Scott | Marbà, Núria | Nikolić, Vedran | Romero, Javier | Duarte, Carlos M. | Alcoverro, Teresa
Uncertainty analyses allow the identification and quantification of the factors that contribute to the potential misclassification of the ecological status of water bodies, helping to improve the sampling design used in monitoring. Here we used a Posidonia oceanica multivariate index (POMI) bio-monitoring dataset covering a total of 81 sites distributed throughout 28 water bodies from the coast of Catalonia, Balearic Islands and Croatia to determine the levels of uncertainty associated with each region and how they change according to the quality status of water bodies. Overall, variability among sites (meadows) within water bodies was the factor that generated the greatest risk of misclassification among the three regions, within which the Balearic Islands had the lowest uncertainty, followed by Croatia and Catalonia. When water bodies classified in good/high quality were separated from those in moderate/poor status classes, we found that the latter displayed higher levels of uncertainty than the former.
Показать больше [+] Меньше [-]Differential biomagnification of PCB, PBDE, Hg and Radiocesium in the food web of the European hake from the NW Mediterranean
2012
Harmelin-Vivien, M. L. (Mireille L.) | Bodiguel, Xavier | Charmasson, Sabine | Loizeau, Véronique | Mellon-Duval, Capucine | Tronczyński, Jacek | Cossa, Daniel
Consumption of marine organisms represents one of the main exposure sources of contaminants for human populations. To obtain a global view of the contamination in commercial fish in the NW Mediterranean Sea, we analysed four types of priority contaminants (PCBs, PBDEs, Hg and ¹³⁷Cs) in the European hake, Merluccius merluccius, from the Gulf of Lions in relation with organism’s trophic level (δ¹⁵N). All contaminants presented a significant increase in concentration in hake muscle with trophic level. However, obvious differences between contaminants were evidenced. Biomagnification factors (BMF and FWMF) along the hake food web were higher for Hg and CB-153 than for BDE-47 and ¹³⁷Cs, and increase in contaminant concentration with trophic level occurred at different rates depending on contaminants. Such differences of biomagnification patterns can be related to physico-chemical properties of the different contaminants.
Показать больше [+] Меньше [-]Perylene dominates the organic contaminant profile in the Berau delta, East Kalimantan, Indonesia
2012
Booij, Kees | Arifin, Zainal | Purbonegoro, Triyoni
The geographical distributions of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), hexachlorobenzene, and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethene (4,4′-DDE) were studied in the Berau delta (East Kalimantan, Indonesia), using sediment sampling and passive water sampling with semipermeable membrane devices. High concentrations of perylene were observed in sediments (54–580ngg⁻¹ dry weight), and water (1–680pgL⁻¹). Perylene accounted for about 60% of the total concentrations of PAHs in the sediment. The relative abundance of the other PAHs was indicative of petrogenic sources. Concentrations of PCBs, hexachlorobenzene, and 4,4′-DDE in sediments were below or close to the detection limit (∼0.02ngg⁻¹). The analysis of a sediment core revealed no appreciable changes in the concentration of target compounds over the past three decades. We show that sediment sampling and passive water sampling are complementary techniques, and propose to bring the results of both methods to the same concentration scale, using locally derived sediment–water partition coefficients.
Показать больше [+] Меньше [-]Use of aliphatic hydrocarbons to infer terrestrial organic matter in coastal marine sediments off China
2012
Liu, Liang-Ying | Wang, Ji-Zhong | Guan, Yu-Feng | Zeng, E. Y. (Eddy Y.)
Sediment samples from the marine systems along the coast of China, covering Yellow Sea, inner shelf of the East China Sea (ECS) and the South China Sea (SCS), were analyzed for n-alkanes and organic carbon. The concentrations of Σn–C₁₅–₃₅ were 120–1680ngg⁻¹ dry weight with an average of 560ngg⁻¹. Short-chain n-alkanes (<C₂₁) in Yellow Sea and the SCS were derived from mixed bacteria and planktonic sources, while those in the ECS inner shelf were mainly of planktonic sources. Long-chain n-alkanes (>C₂₁) were mainly derived from terrestrial higher plants. Organic carbon deposited into Yellow Sea and Southeast Hainan within the SCS was mainly of terrestrial (13–110%; mean: 58%) and marine (48–110%; mean: 86%) sources, respectively. On the other hand, organic carbon accumulated in the SCS adjacent to the Pearl River Estuary was derived from both terrestrial and marine sources.
Показать больше [+] Меньше [-]Onshore ballast water treatment: A viable option for major ports
2012
Pereira, Newton Narciso | Brinati, Hernani Luiz
Ballast water treatment consists of the elimination of exotic species. Currently, the development of alternative methods for this process is directed toward treatment onboard ships. However, we present onshore treatment as a viable alternative for ballast water treatment. We investigated onshore treatment in two iron ore ports with movement capacities of 25 and 90million tons annually (Mta) that receive 7.5 and 25million cubic meters annually (Mm³) of ballast water, respectively. Discrete event simulation was used as the method of analysis, considering the processes of arrival, berthing, ship loading and capture and treatment of ballast water. We analyzed data from 71 ships operating in these ports to validate our simulation model. We were able to demonstrate that onshore treatment does not impact the cargo capacity, occupation rate or average queuing time of ships at these ports. We concluded that implementation of onshore ballast water treatment may be practicable in ports that receive high volumes of ballast water.
Показать больше [+] Меньше [-]Overview of the 20th century impact of trace metal contamination in the estuaries of Todos os Santos Bay: Past, present and future scenarios
2012
Hatje, Vanessa | Barros, Francisco
This paper discusses the distribution patterns of trace metals in sediments and suspended particulate matter (SPM) in the three main estuaries of the Todos os Santos Bay (BTS), Brazil, during dry and rainy seasons. Data available up to 2012 was also reviewed to assess the status of contamination. For most elements, metal concentrations in sediments decreased from the tidal limits to the lower estuary. Metals in SPM presented more complex distributions along the salinity gradient. Metal variability between rainy and dry conditions was only significant for SPM data. Of the BTS estuaries, the levels of Cd, Zn, Pb and Cu are highest in the Subaé estuary, and they seem to be promoting harmful biological effects in macrofauna, and also may pose potential human health risks. Despite the evidence of important localized contamination, much of the data compiled indicates that the bay and its estuaries are still relatively preserved.
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