An overview of the spatial and temporal variations of the environmental accidents in China in recent years was presented in this paper using available data. The results showed that the frequency of pollution accidents was significantly decreased, from 3462 in 1990 to 462 in 2007. The water and air pollution accidents were found to be the dominant types, accounting for more than 80% of the total accidents. Considering the classification of environmental accidents at 4 scales, the general environmental accident, i.e., the least serious type, was the most frequent event, taking up 58.98% of the total pollution accidents. In addition, the distribution of environmental accidents was generally in accordance with the industrial layout in the country during the past decade. It is very important to note that the extraordinarily severe environmental accidents showed an increasing trend in underdeveloped regions, which was caused by the transfer and the development of heavy polluted industry in these areas. As to the losses of environmental accidents, the casualties presented an obvious reduction tendency, while the direct economic loss per accident tended to climb up. Furthermore, some key factors that affect the spatial and temporal tendencies of environmental accidents in China were discussed and some suggestions were put forward, hoping to shed light on environmental risk management and emergency plans making associated with environmental accidents in China. 相似文献
Magnetic parameters and heavy metal concentrations of road dusts collected from two parks with distance about 16 km in Wuhan city, China, were measured. The Guishan Park is circled by main roads with heavy traffic, and the Moshan Park is located on the downwind hills of steelworks and a power plant. Mean values of magnetic susceptibility (??) and saturation magnetization (Ms) of the dusts from the Moshan Park are 1.31 and 1.57 times those from the Guishan Park, respectively. Their magnetic mineralogy is dominated by pseudo-single domain magnetite; however, minor hematite was also identified in those from the Guishan Park. The dominant sources of non-natural magnetic particles and heavy metals were inferred as windblown emissions from the steelworks and the power plant for the Moshan Park, and road/railway traffics for the Guishan Park, respectively. Spatial variation in magnetic properties of road dust in the two parks and their different magnetic behavior propose that the magnetic measurements are sensitive to the different pollutant origins, as well as the urban environment, and that magnetic techniques have a high efficiency in mapping urban environment. Correlation between magnetic parameters and heavy metal concentrations is strongly site-specific: strong correlations were observed in the Moshan Park with correlation coefficients generally higher than 0.800, whereas correlations are poor in the Guishan Park. Therefore, it is strongly recommended that these relationships should be examined thoroughly before magnetic mapping. 相似文献
Pseudomonas sp. Y-5, a strain with simultaneous nitrification and denitrification (SND) capacity, was isolated from the Wuhan Municipal Sewage Treatment Plant. This strain could rapidly remove high concentrations of inorganic nitrogen. Specifically, Pseudomonas sp. Y-5 removed 103 mg/L of NH4+-N in 24 h without nitrate or nitrite accumulation when NH4+-N was its sole nitrogen source. The NH4+-N removal efficiency (RE) was 97.26%, and the average removal rate (RR) was 4.30 mg/L/h. Strain Y-5 also removed NO3?-N and NO2?-N even in aerobic conditions, with average RRs of 4.39 and 4.23 mg/L/h, respectively, and REs of up to 99.34% and 95.81% within 24 h. When cultured in SND medium (SNDM-1), strain Y-5 achieved an NH4+-N RE of up to 97.80% and a total nitrogen (TN) RE of 93.01%, whereas NO3?-N was fully depleted in 48 h. Interestingly, high nitrite concentrations did not inhibit the nitrification capacity of Y-5 when grown in SNDM-2, the RE of NH4+-N and TN reached 96.29% and 94.26%, respectively, and nitrite was consumed completely. Strain Y-5 also adapted well to high concentrations of ammonia (~401.68 mg NH4+-N/L) or organic nitrogen (~315.12 mg TN/L). Our results suggested that Pseudomonas sp. Y-5 achieved efficient simultaneous nitrification and denitrification, thus demonstrating its potential applicability in the treatment of nitrogen-polluted wastewater.
Environmental Science and Pollution Research - Metal toxicity can largely affect the growth and yield of numerous plant species. Plants have developed specific mechanisms to withstand the varying... 相似文献
Environmental Science and Pollution Research - It is well accepted that diesel exhaust particles (DEPs) are highly associated with improper function of organ systems. In this study, DEP toxicity... 相似文献
Three groups of cobalt mixed oxide catalysts(Mg/Zn-Co, Mg/Zn-Ce-C, K/Na-Mg/Zn-Ce-Co)were prepared by sol-gel or impregnation methods. The synergistic effects of transition metal, rare earth metal and alkali metal on cobalt mixed catalysts for nitrous oxide(N2O)decomposing to N2 and O2were investigated. The experimental results revealed that the catalytic activity for N2 O decomposition was promoted as Co2+was replaced partially by Zn2+/Mg2+, moreover, the characterization analysis by XRD and XPS showed that Zn2+/Mg2+replaced Co2+successfully into the spinel structure of Co3O4 and promoted significantly the catalytic activity. Especially, the addition of CeO2 and K2O/Na2O decreased the binding energy and resulted in an increase in the density of the electron cloud around Co and an improvement of the catalytic activity. Of the investigated cobalt mixed catalysts, the best catalytic activity was shown by 2% K-Zn0.5-Ce0.05-Co catalyst. 相似文献