خيارات البحث
النتائج 451 - 460 من 2,512
Analysis of daily average PM10 predictions by generalized linear models in Brno, Czech Republic النص الكامل
2014
Huebnerova, Zuzana | Michalek, Jaroslav
Ambient air quality assessment and management plays an important role in the current European Union policy. Among others, air pollution by PM10 is being monitored. A previous analysis of PM10 aimed at identifying factors affecting air pollution in stations in the City of Brno using available observed meteorological variables. However, the studied model cannot be used for predicting the level of PM10 pollution because the included meteorological variables are not available exactly at the time when the prediction is requested. In that case, we should base the predictions on available predicted variables, namely on temperature, wind direction, wind speed, and cloud cover. A comparison of obtained predictions with the observed values of PM10 during a testing period allows us to evaluate a loss of prediction quality when the predicted covariates are used instead of the observed ones. The presented analysis based on test of symmetry and test of homogeneity of the marginal distribution of two–way contingency tables shows that the loss of prediction quality by employing the predicted meteorological variables is non–significant in the studied case. This observation suggests that the model with predicted meteorological variables can be employed in environmental management processes.
اظهر المزيد [+] اقل [-]The influence of pearl oyster farming on reef fish abundance and diversity in Ahe, French Polynesia النص الكامل
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.
اظهر المزيد [+] اقل [-]Organochlorine pesticide content and distribution in coastal seafoods in Zhoushan, Zhejiang Province النص الكامل
2014
Wang, Jie-yu | Yu, Xin-wei | Fang, Li
Thirteen types of seafoods were collected from four counties (districts) of Zhoushan, Zhejiang Province, China and analyzed for organochlorine pesticides (OCPs). The average concentrations of OCPs in seafoods ranged from 258.3ngg−1 (lw) to 3459.6ngg−1 (lw). Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were the most abundant compounds in these environments and in total accounted for 8.2–62.2% and 32.1–89.0% of the total OCPs in seafoods, respectively. The total OCP contents were higher in seafoods from Shengsi and Putuo and lower in those from Dinghai and Daishan. The ratios of (DDE+DDD)/DDTs reflected a mixed input of accumulated and fresh DDTs in Shengsi, Putuo. The ratios of o,p′-DDT/p,p′-DDT in seafoods of Shengsi ranged 0.10–0.60 (mean 0.33), indicating that DDTs in seafoods of Shengsi may partly contain dicofol products and other pollutants accumulated in Yangtze Estuary. DDTs are a greater concern for ecotoxicological risk in the study area.
اظهر المزيد [+] اقل [-]Source speciation resolving hydrochemical complexity of coastal aquifers النص الكامل
2014
Sonkamble, Sahebrao | Chandra, Subash | Ahmed, Shakeel | Rangarajan, R.
There is a growing concern of seawater intrusion to freshwater aquifers due to groundwater overexploitation in the eastern coastal belt of Southern India. The problem becomes complex in the regions where industrial effluents are also contaminating the freshwater aquifers. In order to understand the hydrochemical complexity of the system, topographic elevation, static water level measurements, major ion chemistry, ionic cross plots, water type contours and factor analysis were applied for 144 groundwater samples of shallow and deep sources from Quaternary and Tertiary coastal aquifers, located within the industrial zone of 25 km2 area near Cuddalore, Southern India. The ionic cross plots indicates dissolution of halite minerals from marine sources and seawater mixing into inland aquifers up to the level of 9.3%. The factor analysis explains three significant factors totaling 86.3% of cumulative sample variance which includes varying contribution from marine, industrial effluent and freshwater sources.
اظهر المزيد [+] اقل [-]Measurement of PCDD/Fs emissions from a coal–fired power plant in Malaysia and establishment of emission factors النص الكامل
2014
This paper presents the PCDD/Fs emissions measured from a coal–fired power plant in Malaysia. The study discusses partitioning of PCDD/Fs in particle and gas phase, effects of coal quality to PCDD/Fs formation, effects of air pollution control device (APCD) configuration to PCDD/Fs formation and establishment of emission factors of PCDD/Fs from the studied coal–fired power plant. The results presented in this study were mostly in good agreement with the previous works on PCDD/Fs emissions conducted in other countries. Laboratory analysis results showed that PCDFs were the dominant congeners. The emissions of PCDD/Fs were low which most probably due to the high combustion efficiency. The PCDFs/PCDDs ratio was more than 1 and PCDD/Fs were detected in fly ash, hence speculating that the formation of PCDD/Fs during coal combustion was mainly through de novo synthesis. Analysis on partitioning of PCDD/Fs showed that the compounds were mainly emitted in gas phase. This study also indicated that type of coal influenced the formation of PCDD/Fs during coal combustion where bituminous coal with high sulfur (S) content resulted in slightly lower PCDD/Fs emissions compared to sub–bituminous coal. It was also found that operation of flue gas desulfurization (FGD) reduced the emission of PCDD/Fs. The established emission factors for PCDD/Fs were in the range of 0.08 to 0.11ng I–TEQ/kg.
اظهر المزيد [+] اقل [-]Diving associated coral breakage in Hong Kong: Differential susceptibility to damage النص الكامل
2014
We conducted the first quantitative assessment of coral breakage along a gradient of diving activities in Hong Kong, the most densely populated city in southern China. A survey of six 1×25m transects at seven sites revealed a total of 81 broken corals, among which 44% were branching, 44% plate-like and 12% massive. There were 3–19 broken colonies per site. At most study sites, the percentage of broken corals exceeded the recommended no-action threshold of 4%, suggesting that management intervention is justified. There was a significant positive correlation between the number of broken coral colonies and the number of divers visiting the site. The branching Acropora and the plate-like Montipora suffered from much higher frequency of damage than their relative abundance, raising the concern that the cumulative impact of such differential susceptibility to breakage may affect coral community composition.
اظهر المزيد [+] اقل [-]Organic contamination of surface sediments in the metropolitan coastal zone of Athens, Greece: Sources, degree, and ecological risk النص الكامل
2014
Kapsimalis, V. | Panagiotopoulos, I.P. | Talagani, P. | Hatzianestis, I. | Kaberi, H. | Rousakis, G. | Kanellopoulos, T.D. | Hatiris, G.A.
Bottom sediments represent a crucial component of the marine environment, since they constitute a habitat, a trophic resource, and a spawning place for various organisms. Unfortunately, the sediments of urban coastal areas are deeply impacted by anthropogenic activities that degrade their quality. In the Drapetsona–Keratsini metropolitan coastal zone of Athens, current industrial and shipping activities together with the effluents from a sewage outfall, which was in operation in the past, have resulted in one of the most contaminated sedimentary environments, in terms of organic compound loads, in Mediterranean. Exceptionally high concentrations of aliphatic hydrocarbons (up to 4457μgg−1), carcinogenic PAHs (up to 7284ngg−1), and organochlorines (up to 544ngg−1 for PCBs; up to 208ngg−1 for DDTs) constitute a major threat to the marine life of the associated Saronikos Gulf.
اظهر المزيد [+] اقل [-]Radioactivity concentrations in mussel (Mytilus galloprovincialis) of Turkish Sea coast and contribution of 210Po to the radiation dose النص الكامل
2014
Kılıç, Önder | Belivermiş, Murat | Çotuk, Yavuz | Topçuoğlu, Sayhan
Radionuclides levels were determined in indigenous and transplanted mussels (Mytilus galloprovincialis) collected from Turkish marine environment. Radioactivity concentrations of 137Cs, 40K, 226Ra, 228Ra, 210Po and 210Pb were determined in the soft tissues of the mussel samples collected in Bosphorus Strait, Coasts of Black Sea, Marmara Sea and Aegean Sea. Mussel transplantation was carried out by using mussel cages in Levantine Sea coast since M. galloprovincialis did not naturally adapt along the coast. The average activity concentrations of 137Cs, 40K, 226Ra, 228Ra, 210Po and 210Pb in the coastline of Turkey were found to be 0.7±0.1, 469±24, 0.9±0.1, 1.0±0.1, 122±4 and 10.9±0.9Bqkg−1 in dry weight (dw), respectively. The average of 210Po/210Pb ratio was found to be ∼14. Total annual effective 210Po dose was calculated to be in the range of 0.25–3.30 μSv due to mussel consumption. Radioactivity and dose levels were compared with those of similar studies carried out in Mediterranean countries.
اظهر المزيد [+] اقل [-]Distributions of polycyclic aromatic hydrocarbons and alkylated polycyclic aromatic hydrocarbons in Osaka Bay, Japan النص الكامل
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.
اظهر المزيد [+] اقل [-]Levels of Cd, Cu, Pb and V in marine sediments in the vicinity of the Single Buoy Moorings (SBM3) at Mina Al Fahal in the Sultanate of Oman النص الكامل
2014
Al-Husaini, Issa | Abdul-Wahab, Sabah | Ahamad, Rahmalan | Chan, Keziah
Recently in the Sultanate of Oman, there has been a rapid surge of coastal developments. These developments cause metal contamination, which may affect the habitats and communities at and near the coastal region. As a result, a study was conducted to assess the level of metal contamination and its impact on the marine sediments in the vicinity of the Single Buoy Moorings 3 (SBM3) at Mina Al Fahal in the Sultanate of Oman. Marine subtidal sediment samples were collected from six different stations of the SBM3 for the period ranging from June 2009 to April 2010. These samples were then analyzed for their level and distribution of the heavy metals of cadmium (Cd), copper (Cu), lead (Pb) and vanadium (V). Overall, low concentrations of all four heavy metals were measured from the marine sediments, indicating that the marine at SBM3 is of good quality.
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