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281.
Endemic fluorosis exists in almost all provinces of China. The long-term ingestion of groundwater containing high concentrations of fluoride is one of the main causes of fluorosis. We used artificial neural network to model the relationship between groundwater fluoride concentrations from throughout China and environmental variables such as climatic, geological. and soil parameters as proxy predictors. The results show that the accuracy and area under the receiver operating characteristic curve of the model in the test dataset are 80.5% and 0.86%, respectively, and climatic variables are the most effective predictors. Based on the artificial neural network model, a nationwide prediction risk map of fluoride concentrations exceeding 1.5 mg/L with a 0.5 × 0.5 arc minutes resolution was generated. The high risk areas are mainly located in western provinces of Xinjiang, Tibet, Qinghai, and Sichuan, and the northern provinces of Inner Mongolia, Hebei and Shandong. The total number of people estimated to be potentially at risk of fluorosis due to the use of untreated high fluoride groundwater as drinking water is about 89 million, or 6% of the population. The high fluoride groundwater risk map helps the authorities to prioritize areas requiring mitigation measures and thus facilitates the implementation of water improvement and defluoridation projects. 相似文献
282.
Vapor wall losses can affect the yields of secondary organic aerosol. The effects of surface-to-volume (S/V) ratio and relative humidity (RH) on the vapor-wall interactions were investigated in this study. The oxygenated volatile organic compounds (OVOCs) were generated from toluene-H2O2 irradiations. The average gas to wall loss rate constant (kgw) of OVOCs in a 400 L reactor (S/V = 7.5 m−1) is 2.47 (2.41 under humid conditions) times higher than that in a 5000 L reactor (S/V = 3.6 m−1) under dry conditions. In contrast, the average desorption rate constant (kwg) of OVOCs in 400 L reactor is only 1.37 (1.20 under humid conditions) times higher than that in 5000 L reactor under dry conditions. It shows that increasing the S/V ratio can promote the wall losses of OVOCs. By contrast, the RH effect on kgw is not prominent. The average kgw value under humid conditions is almost the same as under dry conditions in the 400 L (5000 L) reactor. However, increasing RH can decrease the desorption rates. The average kwg value under dry conditions is 1.45 (1.27) times higher than that under humid conditions in the 400 L (5000 L) reactor. The high RH can increase the partitioning equilibrium timescales and enhance the wall losses of OVOCs. 相似文献
283.
A monitoring method based on solvent extraction of adsorbed target glymes followed by gas chromatograph-mass spectrometry GC-MS analysis was developed for seven glymes, namely ethylene glycol dimethyl ether, propylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether. The best recoveries of target glymes were achieved when using a combination of sample collection medium of graphitised carbon black (GCB) with a solvent mixture of methylene chloride and methanol (95/5, v/v). Method detection limits ranged from 1.5 microg/m3 for diethylene glycol diethyl ether to 13.2 microg/m3 for ethylene glycol diethyl ether based on a sample volume of 3.4 1. Using this method, diethylene glycol dimethyl ether and diethylene glycol diethyl ether were detected and measured successfully in diluted vehicle exhausts in diesel fuel engine tests. 相似文献
284.
Xinxin Hu Wei Shi Fu Cao Guanjiu Hu Yingqun Hao Si Wei Xinru Wang Hongxia Yu 《Chemosphere》2013,90(7):2123-2128
The estrogenic activities of source water from Yangtze River, Huaihe River, Taihu Lake and groundwater in Yangtze River Delta in the dry and wet season were determined by use of reporter gene assays based on African green monkey kidney (CV-1) cell lines. Higher estrogenic activities were observed in the dry season, and the estrogenic potentials in water samples from Taihu Lake were greater than other river basins. None of the samples from groundwater showed estrogen receptor (ER) agonist activity. The 17β-Estradiol (E2) equivalents (EEQs) of water samples in the dry season ranged from 9.41 × 10?1 to 1.20 × 101 ng E2 L?1. In the wet season, EEQs of all the water samples were below the detection limit as 9.00 × 10?1 ng E2 L?1 except for one sample from Huaihe River. The highest contribution of E2 was detected in Yangtze River as 99% of estrogenic activity. Nonylphenol (NP, 100% detection rate) and octylphenol (OP, 100% detection rate) might also be responsible for the estrogenic activities in water sources. Potential health risk induced by the estrogenic chemicals in source water may be posed to the residents through water drinking. 相似文献
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Miscanthus for Renewable Energy Generation: European Union Experience and Projections for Illinois 总被引:1,自引:0,他引:1
Heaton Emily A. Long Stephen P. Voigt Thomas B. Jones Michael B. Clifton-Brown John 《Mitigation and Adaptation Strategies for Global Change》2004,9(4):433-451
Mitigation and Adaptation Strategies for Global Change - 相似文献
287.
Wan Kailiang Long Wenjun 《中国人口.资源与环境(英文版)》2007,5(4):42-48
The issue of agricultural insurance subsidy is discussed in this paper aiming to make it provided more rationally and scientifically. It is started with the connection between agricultural insurance and financial subsidy. It is really necessary and crucial to implement the financial insurance due to the bad operational performance, especially in the developing countries. But the subsidy should be provided more rationally because financial subsidy has lots of negative effects. A model in competitive insurance markets developed by Ahsan et al (1982) and a farmers' decision model are developed to solve the optimal subsidized rate. Finally, the equation is got to calculate it. But a quantitative subsidized rate is not made here because the calculation should be under some restricted conditions, which are always absent in the developing countries. So the government should provide some subsidy for the ex ante research and preparation to get the scientific probability and premium rate. 相似文献
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