خيارات البحث
النتائج 1931 - 1940 من 1,956
Identification and removal of polycyclic aromatic hydrocarbons in wastewater treatment processes from coke production plants النص الكامل
2013
Zhang, Wanhui | Wei, Chaohai | Yan, Bo | Feng, Chunhua | Zhao, Guobao | Lin, Chong | Yuan, Mengyang | Wu, Chaofei | Ren, Yuan | Hu, Yun
Identification and removal of polycyclic aromatic hydrocarbons (PAHs) were investigated at two coke plants located in Shaoguan, Guangdong Province of China. Samples of raw coking wastewaters and wastewaters from subunits of a coke production plant were analyzed using gas chromatography-mass spectrometry (GC/MS) to provide a detailed chemical characterization of PAHs. The identification and characterization of PAH isomers was based on a positive match of mass spectral data of sample peaks with those for PAH isomers in mass spectra databases with electron impact ionization mass spectra and retention times of internal reference compounds. In total, 270 PAH compounds including numerous nitrogen, oxygen, and sulfur heteroatomic derivatives were positively identified for the first time. Quantitative analysis of target PAHs revealed that total PAH concentrations in coking wastewaters were in the range of 98.5 ± 8.9 to 216 ± 20.2 μg/L, with 3-4-ring PAHs as dominant compounds. Calculation of daily PAH output from four plant subunits indicated that PAHs in the coking wastewater came mainly from ammonia stripping wastewater. Coking wastewater treatment processes played an important role in removing PAHs in coking wastewater, successfully removing 92 % of the target compounds. However, 69 weakly polar compounds, including PAH isomers, were still discharged in the final effluent, producing 8.8 ± 2.7 to 31.9 ± 6.8 g/day of PAHs with potential toxicity to environmental waters. The study of coking wastewater herein proposed can be used to better predict improvement of coke production facilities and treatment conditions according to the identification and removal of PAHs in the coke plant as well as to assess risks associated with continuous discharge of these contaminants to receiving waters.
اظهر المزيد [+] اقل [-]Organochlorine pesticides and polychlorinated biphenyls in soils surrounding the Tanggu Chemical Industrial District of Tianjin, China النص الكامل
2013
Hou, Hong | Zhao, L. | Zhang, J. | Xu, Y. F. | Yan, Z. G. | Bai, L. P. | Li, F. S.
The spatial distribution of persistent organic pollutants (POPs) was examined in soils surrounding the Tanggu Chemical Industrial District in Tianjin, China. The concentrations of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs), hexachlorobenzenes (HCBs), and polychlorinated biphenyls (PCBs) were determined in 70 surface soils using accelerated solvent extraction and gas chromatography with electron capture detection. The results showed that the ranges of ∑HCH, ∑DDT, ΣHCB, and ∑PCB concentrations in soils were 2.1–12,549 μg kg⁻¹ (average, 965 μg kg⁻¹), n.d.–2,033 μg kg⁻¹ (average, 88.4 μg kg⁻¹), n.d.–1,924 μg kg⁻¹ (average, 349 μg kg⁻¹), and n.d.–373 μg kg⁻¹ (average, 46.2 μg kg⁻¹), respectively. Of these, HCHs were the dominant POPs, accounting for 75 % of the total organochlorine pesticide (OCP) residues. Overall, the spatial distribution of OCP concentrations showed a decreasing trend from the center of the Tanggu District to the surrounding areas. Two major pollution sources were Tianjin Dagu Chemical Co., Ltd. in the district center and the Tianjin Chemical Plant in Hangu District. In contrast, PCB concentrations were relatively high in the Haihe estuary to the east and low to the west of the study area. Component analysis of OCPs in these soils showed that they mainly came from industrial point sources. Compared with soils in other regions, soil DDT pollution was at a medium level in the Tanggu Chemical Industrial District, but associated HCH, HCB, and PCB pollution was relatively heavy. By multivariate statistical analyses, Tianjin Dagu Chemical Co., Ltd. was recognized as the main source of POPs, and soil properties were clarified to play an important role on the distribution and composition of POPs, especially the organic carbon content.
اظهر المزيد [+] اقل [-]Performance evaluation of various stormwater best management practices النص الكامل
2013
Yu, Jianghua | Yu, Haixia | Xu, Liqiang
Many best management practices have been developed and implemented to treat the nonpoint source pollution of the aquatic environment in Korea's four major river basins. The performance and cost of these facilities were evaluated and compared using broad categories, including grassed swales, constructed wetlands, vegetated filter strips, hydrodynamic separators, media filters, and infiltration trenches, based on the monitoring and maintenance work undertaken between 2005 and 2012. Constructed wetlands, media filters, and infiltration trenches generally performed better in removing pollutants than other types of facilities, while media filters were the most expensive factor in terms of construction and operational costs. In addition, constructed wetlands incurred the least operational cost, as well as helping to control the quantity of runoff. This illustrates that a high cost facility does not necessarily give a better performance. A slightly more expensive facility, such as wetland, could prove to be a reasonably effective treatment. The selection of the most appropriate treatment for stormwater runoff should be based on an overall analysis of performance and cost.
اظهر المزيد [+] اقل [-]Spatial modelling for nitrogen leaching from intensive farming in Red River Delta of Vietnam
2013
Mai, V.T. | Hoanh, Chu Thai | Keulen, H. van | Hessel, R.
Spatial modelling for nitrogen leaching from intensive farming in Red River Delta of Vietnam
2013
Mai, V.T. | Hoanh, Chu Thai | Keulen, H. van | Hessel, R.
In this study, a spatial dynamic model was developed, to simulate nitrogen dynamics in Van Hoi commune, Tam Duong district, Vietnam, for different soil and land use types, under different irrigation and fertilizer regimes. The model has been calibrated using measured nitrogen concentrations in soil solution in March and August 2004 and validated for data from March and August 2005. Lateral flow was low in this level area. Percolation was the main process leading to high nitrogen leaching losses to ground water. Calculated annual leaching losses varied from 88 to 122 kg N ha-1 in flowers, 64 to 82 in vegetables of the cabbage group, 51 to 76 in chili, 56 to 75 in vegetables of the squash group, and 36 to 55 in rice.
اظهر المزيد [+] اقل [-]Spatial modelling for nitrogen leaching from intensive farming in Red River Delta of Vietnam
2013
Mai, V. T. | Hoanh, Chu Thai | Van Keulen, H. | Hessel, R.
In this study, a spatial dynamic model was developed, to simulate nitrogen dynamics in Van Hoi commune, Tam Duong district, Vietnam, for different soil and land use types, under different irrigation and fertilizer regimes. The model has been calibrated using measured nitrogen concentrations in soil solution in March and August 2004 and validated for data from March and August 2005. Lateral flow was low in this level area. Percolation was the main process leading to high nitrogen leaching losses to ground water. Calculated annual leaching losses varied from 88 to 122 kg N ha–1 in flowers, 64 to 82 in vegetables of the cabbage group, 51 to 76 in chili, 56 to 75 in vegetables of the squash group, and 36 to 55 in rice.
اظهر المزيد [+] اقل [-]The impact of indoor air pollution on the incidence of life threatening respiratory illnesses: Evidence from young children in Peru النص الكامل
2013
Gajate-Garrido, Gissele
Meteorology النص الكامل
2013
Raspe, Stephan | Bastrup-Birk, Annemarie | Fleck, Stefan | Weis, Wendelin | Mayer, Helmut | Meesenburg, Henning | Wagner, Markus | Schindler, Dirk | Gartner, Karl
A probabilistic model estimating oil spill clean-up costs - a case study for the Gulf of Finland النص الكامل
2013
Montewka, Jakub | Weckström, Mia | Kujala, Pentti
A probabilistic model estimating oil spill clean-up costs - a case study for the Gulf of Finland النص الكامل
2013
Montewka, Jakub | Weckström, Mia | Kujala, Pentti
Existing models estimating oil spill costs at sea are based on data from the past, and they usually lack a systematic approach. This make them passive, and limits their ability to forecast the effect of the changes in the oil combating fleet or location of a spill on the oil spill costs. In this paper we make an attempt towards the development of a probabilistic and systematic model estimating the costs of clean-up operations for the Gulf of Finland. For this purpose we utilize expert knowledge along with the available data and information from literature. Then, the obtained information is combined into a framework with the use of a Bayesian Belief Networks. Due to lack of data, we validate the model by comparing its results with existing models, with which we found good agreement. We anticipate that the presented model can contribute to the cost-effective oil-combating fleet optimization for the Gulf of Finland. It can also facilitate the accident consequences estimation in the framework of formal safety assessment (FSA).
اظهر المزيد [+] اقل [-]A probabilistic model estimating oil spill clean-up costs – A case study for the Gulf of Finland النص الكامل
2013
Montewka, Jakub | Weckström, Mia | Kujala, P.
Existing models estimating oil spill costs at sea are based on data from the past, and they usually lack a systematic approach. This make them passive, and limits their ability to forecast the effect of the changes in the oil combating fleet or location of a spill on the oil spill costs.In this paper we make an attempt towards the development of a probabilistic and systematic model estimating the costs of clean-up operations for the Gulf of Finland. For this purpose we utilize expert knowledge along with the available data and information from literature. Then, the obtained information is combined into a framework with the use of a Bayesian Belief Networks. Due to lack of data, we validate the model by comparing its results with existing models, with which we found good agreement.We anticipate that the presented model can contribute to the cost-effective oil-combating fleet optimization for the Gulf of Finland. It can also facilitate the accident consequences estimation in the framework of formal safety assessment (FSA).
اظهر المزيد [+] اقل [-]Seawater carbonate chemistry and reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica in a laboratory experiment النص الكامل
2013
Kita, Jun | Kikkawa, Takashi | Asai, Takamasa | Ishimatsu, Atsushi
Seawater carbonate chemistry and reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica in a laboratory experiment النص الكامل
2013
Kita, Jun | Kikkawa, Takashi | Asai, Takamasa | Ishimatsu, Atsushi
We investigated the effects of elevated pCO2 in seawater both on the acute mortality and the reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica with the purpose of accumulating basic data for assessing potential environmental impacts of sub-sea geological storage of anthropogenic CO2 in Japan. Acute tests showed that nauplii of T. japonicus have a high tolerance to elevated pCO2 environments. Full life cycle tests on T. japonicus indicated NOEC = 5800 µatm and LOEC = 37,000 µatm. Adult B. japonica showed remarkable resistance to elevated pCO2 in the acute tests. Embryonic development of B. japonica showed a NOEC = 1500 µatm and LOEC = 5400 µatm. T. japonicus showed high resistance to elevated pCO2 throughout the life cycle and B. japonica are rather sensitive during the veliger stage when they started to form their shells.
اظهر المزيد [+] اقل [-]Effects of elevated pCO2 on reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica النص الكامل
2013
We investigated the effects of elevated pCO2 in seawater both on the acute mortality and the reproductive properties of the benthic copepod Tigriopus japonicus and gastropod Babylonia japonica with the purpose of accumulating basic data for assessing potential environmental impacts of sub-sea geological storage of anthropogenic CO2 in Japan. Acute tests showed that nauplii of T. japonicus have a high tolerance to elevated pCO2 environments. Full life cycle tests on T. japonicus indicated NOEC=5800μatm and LOEC=37,000μatm. Adult B. japonica showed remarkable resistance to elevated pCO2 in the acute tests. Embryonic development of B. japonica showed a NOEC=1500μatm and LOEC=5400μatm. T. japonicus showed high resistance to elevated pCO2 throughout the life cycle and B. japonica are rather sensitive during the veliger stage when they started to form their shells.
اظهر المزيد [+] اقل [-]Towards supersites in forest ecosystem monitoring and research النص الكامل
2013
Mikkelsen, Teis Nørgaard | Clarke, Nicholas | Danielewska, Alina | Fischer, Richard