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Результаты 1031-1040 из 3,243
Antibiotics in typical marine aquaculture farms surrounding Hailing Island, South China: Occurrence, bioaccumulation and human dietary exposure
2015
Chen, Hui | Liu, Shan | Xu, Xiang-Rong | Liu, Shuang-Shuang | Zhou, Guang-Jie | Sun, Kai-Feng | Zhao, Jian-Liang | Ying, Guang-Guo
The occurrence, bioaccumulation, and human dietary exposure via seafood consumption of 37 antibiotics in six typical marine aquaculture farms surrounding Hailing Island, South China were investigated in this study. Sulfamethoxazole, salinomycin and trimethoprim were widely detected in the water samples (0.4–36.9ng/L), while oxytetracycline was the predominant antibiotic in the water samples of shrimp larvae pond. Enrofloxacin was widely detected in the feed samples (16.6–31.8ng/g) and erythromycin–H2O was the most frequently detected antibiotic in the sediment samples (0.8–4.8ng/g). Erythromycin–H2O was the dominant antibiotic in the adult Fenneropenaeus penicillatus with concentrations ranging from 2498 to 15,090ng/g. In addition, trimethoprim was found to be bioaccumulative in young Lutjanus russelli with a median bioaccumulation factor of 6488L/kg. Based on daily intake estimation, the erythromycin–H2O in adult F. penicillatus presented a potential risk to human safety.
Показать больше [+] Меньше [-]Assessing the water quality response to an alternative sewage disposal strategy at bathing sites on the east coast of Ireland
2015
Bedri, Zeinab | O’Sullivan, John J. | Deering, Louise A. | Demeter, Katalin | Masterson, Bartholomew | Meijer, Wim G. | O’Hare, Gregory
A three-dimensional model is used to assess the bathing water quality of Bray and Killiney bathing sites in Ireland following changes to the sewage management system. The model, firstly calibrated to hydrodynamic and water quality data from the period prior to the upgrade of the Wastewater Treatment Works (WwTW), was then used to simulate Escherichia coli (E. coli) distributions for discharge scenarios of the periods prior to and following the upgrade of the WwTW under dry and wet weather conditions. E. coli distributions under dry weather conditions demonstrate that the upgrade in the WwTW has remarkably improved the bathing water quality to a Blue Flag status.The new discharge strategy is expected to drastically reduce the rainfall-related incidents in which environmental limits of the Bathing Water Directive are breached. However, exceedances to these limits may still occur under wet weather conditions at Bray bathing site due to storm overflows that may still be discharged through two sea outfalls offshore of Bray bathing site.
Показать больше [+] Меньше [-]A damage assessment model of oil spill accident combining historical data and satellite remote sensing information: A case study in Penglai 19-3 oil spill accident of China
2015
Wei, Lai | Hu, Zhuowei | Dong, Lin | Zhao, Wenji
Oil spills are one of the major sources of marine pollution; it is important to conduct comprehensive assessment of losses that occur as a result of these events. Traditional methods are required to assess the three parts of losses including cleanup, socioeconomic losses, and environmental costs. It is relatively slow because assessment is complex and time consuming. A relatively quick method was developed to improve the efficiency of assessment, and then applied to the Penglai 19-3 accident. This paper uses an SAR image to calculate the oil spill area through Neural Network Classification, and uses historical oil-spill data to build the relationship between loss and other factors including sea-surface wind speed, and distance to the coast. A multiple regression equation was used to assess oil spill damage as a function of the independent variables. Results of this study can be used for regulating and quickly dealing with oil spill assessment.
Показать больше [+] Меньше [-]Toxicity identification evaluation of sediments in Liaohe River
2015
Ke, Xin | Gao, Lili | Huang, Hao | Kumar, Santosh
Liaohe River has received significant attention in the northeast region and even in the entire country. As part of a recently completed water quality assessment, a series of water column and sediment toxicity tests was performed throughout the watershed. In the current study, we subjected sediments from the Liaohe River to toxicity identification evaluation manipulations and tests for chronic toxicity with midge (Chironomus riparius), with survival as the end point. In Phase I, the sediments were treated with zeolite, cation-exchange resin, and powdered coconut charcoal. Results confirmed that ammonia compounds were the major contaminants in terms of toxicity, although toxic effects from metals were also a concern in at least three sites. In Phase II identification, chemical analysis provided a strong evidence that the metals As and Cd are the probable causes of toxicity in the sediments, without the influence of ammonia. Temporally, ammonia is responsible for the toxicity of the selected sediments.
Показать больше [+] Меньше [-]Development of artificial intelligence based NO2 forecasting models at Taj Mahal, Agra
2015
Mishra, Dhirendra | Goyal, Pramila
The statistical regression and specific computational intelligence based models are presented in this paper for the forecasting of hourly NO2 concentrations at a historical monument Taj Mahal, Agra. The model was developed for the purpose of public health oriented air quality forecasting. Last ten–year air pollution data analysis reveals that the concentration of air pollutants increased significantly. It is also observed that the pollution levels are always higher during the months of November at around Taj Mahal, Agra. Therefore, the hourly observed data during November were used in the development of air quality forecasting models for Agra, India. Firstly, multiple linear regression (MLR) was used for building an air quality–forecasting model to forecast the NO2 concentrations at Agra. Further, a novel approach, based on regression models, principal component analysis (PCA) was analyzed to find the correlations of different predictor variables between meteorology and air pollutants. Then, the significant variables were taken as the input parameters to propose the reliable physical artificial neural network (ANN)-multi layer perceptron model for forecasting of air pollution in Agra. MLR and PCA–ANN models were evaluated through statistical analysis. The correlation coefficients (R) were 0.89 and 0.91 respectively, for PCA–ANN and were 0.69 and 0.89 respectively for MLR in the training and validation periods. Similarly, the values of normalized mean square error (NMSE), index of agreement (IOA) and fractional bias (FB) were in good agreement with the observed values. It was concluded that PCA–ANN model performs better and can be used for forecasting air pollution at Taj Mahal, Agra.
Показать больше [+] Меньше [-]A review of the status and development of Kuwait’s fisheries
2015
Al-Husaini, M. | Bishop, J.M. | Al-Foudari, H.M. | Al-Baz, A.F.
The status of Kuwait’s fisheries landings and relative abundance for major species was reviewed using research data from Kuwait Institute for Scientific Research and landing data from the Kuwait’s Central Statistical Bureau. Landing data showed significant decreases for major commercial species such as zobaidy (Pampus argenteus), suboor (Tenualosa ilisha), hamoor (Epinephelus coioides), newaiby (Otolithes ruber) and hamra (Lutjanus malabaricus) while abundance data for the shrimp Penaeus semisulcatus showed significant reduction in the recent years mainly because of overfishing. The catch-rate data showed continuous decline for major species such as zobaidy, newaiby and hamoor, which indicate that stock abundances of these species are low. The reduction in stock abundance in context with changes in habitat quality, particularly the effects of reduced discharge of the Shatt Al-Arab, is discussed.
Показать больше [+] Меньше [-]Impact of industrial effluents on geochemical association of metals within intertidal sediments of a creek
2015
Volvoikar, Samida P. | Nayak, G.N.
Metal speciation studies were carried out on three intertidal core sediments of the industrially impacted Dudh creek located along west coast of India. Metals indicated a drastic increase in the bioavailable fraction towards the surface of the cores, suggesting an increase in anthropogenic metal input in recent years as compared to the past. Also, when compared with Vaitarna estuary and Khonda creek of Thane district, the speciation of metals in Dudh creek sediments was observed to have been highly modified in recent years. High concentrations of metals associated with bioavailable fractions therefore suggested a risk of toxicity to sediment associated biota of Dudh creek.
Показать больше [+] Меньше [-]Trace metals in the surface sediments of the eastern continental shelf of Hainan Island: Sources and contamination
2015
Xu, Fangjian | Tian, Xu | Yin, Xuebo | Yan, Huimei | Yin, Feng | Liu, Zhaoqing
Major (Al) and trace metal (Cu, Pb, Zn, Cr, Ni, Cd, and As) concentrations in 29 surface sediment samples from the eastern continental shelf of Hainan Island were evaluated to determine the level of contamination. A multivariate analysis indicated that the sources of Cd, As, and Pb were primarily anthropogenic, whereas the sources of Cu, Zn, Cr, and Ni were primarily natural and/or partially anthropogenic. Enrichment factor (EF) and geoaccumulation index (Igeo) values were calculated to assess the anthropogenic contamination in the region. Both the EF and Igeo values indicated relatively elevated Cd and As concentrations. This study provides a useful aid for sustainable marine management in the region.
Показать больше [+] Меньше [-]Reducing microplastics from facial exfoliating cleansers in wastewater through treatment versus consumer product decisions
2015
Chang, Michelle
Microplastics (<5mm) have been discovered in fresh and saltwater ecosystems, sediments, and wastewater effluent around the world. Their ability to persist and accumulate up food chains should be a concern as research is still experimenting with techniques to assess their long-term effects on the environment. I sought to characterize the microbeads found in facial exfoliating cleansers so as to better understand how to reduce this source of pollution through consumer use and wastewater treatment solutions. By sampling products from national-grossing cosmetic personal care brands, I was able to gather information on the size, color, volume, mass, and concentration of polyethylene beads in the cleansers. From that data, I modeled onto a consumer survey the estimated volume of microplastics entering a wastewater stream. Through inquiry, I learned the practices of two local wastewater treatment facilities. My findings show that consumer decisions and treatment protocols both play crucial parts in minimizing microplastic pollution.
Показать больше [+] Меньше [-]Backwash process of marine macroplastics from a beach by nearshore currents around a submerged breakwater
2015
Kataoka, Tomoya | Hinata, Hirofumi | Kato, Shigeru
A key factor for determining the residence time of macroplastics on a beach is the process by which the plastics are backwashed offshore (backwash process). Here, we deduced the backwash process of plastic fishing floats on Wadahama Beach based on the analysis of two-year mark-recapture experiments as well as nearshore current structures revealed by sequential images taken by za webcam installed at the edge of a cliff behind the beach. The analysis results revealed the occurrence of a combination of offshore currents and convergence of alongshore currents in the surf zone in storm events around a submerged breakwater off the northern part of the beach, where 48% of the backwashed floats were last found. We conclude that the majority of the floats on the beach were transported alongshore and tended to concentrate in the convergence zone, from where they were backwashed offshore by the nearshore currents generated in the events.
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