In recent years, groundwater quality has become a global concern due to its effect on human life and natural ecosystems. To assess the groundwater quality in the Amol–Babol Plain, a total of 308 water samples were collected during wet and dry seasons in 2009. The samples were analysed for their physico-chemical and biological constituents. Multivariate statistical analysis and geostatistical techniques were applied to assess the spatial and temporal variabilities of groundwater quality and to identify the main factors and sources of contamination. Principal component analysis (PCA) revealed that seven factors explained around 75 % of the total variance, which highlighted salinity, hardness and biological pollution as the dominant factors affecting the groundwater quality in the Plain. Two-way analysis of variance (ANOVA) was conducted on the dataset to evaluate the spatio-temporal variation. The results showed that there were no significant temporal variations between the two seasons, which explained the similarity between six component factors in dry and wet seasons based on the PCA results. There are also significant spatial differences (p?>?0.05) of the parameters under study, including salinity, potassium, sulphate and dissolved oxygen in the plain. The least significant difference (LSD) test revealed that groundwater salinity in the eastern region is significantly different to the central and western side of the study area. Finally, multivariate analysis and geostatistical techniques were combined as an effective method for demonstrating the spatial structure of multivariate spatial data. It was concluded that multiple natural processes and anthropogenic activities were the main sources of groundwater salinization, hardness and microbiological contamination of the study area. 相似文献
The photochemistry of a major commercial polybrominated diphenyl ether (PBDE) flame retardant congener, 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE153), was investigated in acetonitrile, distilled water, and seawater. After a short irradiation period in acetonitrile at 302 nm, the major photoproducts of BDE153 included 2,2',4,4',5-(BDE99), 2,2',4,5,5'-(BDE101), and 2,4,4',5,5'-(BDE118) substituted penta-BDEs as primary photohydrodebromination products, 2,2',4,4'-(BDE47), 3,3',4,4'-(BDE77), 2,3',4,4'-(BDE66), and 2,2',4,5'-(BDE49) substituted tetra-BDEs as secondary photohydrodebromination products, a suite of non-2,3,7,8-substituted mono- through penta-brominated dibenzofurans, and three tetrabrominated 2-hydroxybiphenyl congeners. By comparison, irradiation in distilled water and seawater gave increased relative photohydrodebromination contributions and no evidence for the formation of brominated dibenzofurans or 2-hydroxybiphenyls. In all solvent systems, subsequent degradation of primary and secondary photoproducts under continuing irradiation led to a steadily decreasing reaction mass balance. The results suggest a short photochemical half-life for BDE153 in aquatic systems, with rapid photohydrodebromination to some of the most prevalent penta- and tetra-brominated diphenyl ether congeners typically observed in environmental matrices. 相似文献
The unsustainable trade in wildlife is a key threat to Earth's biodiversity. Efforts to mitigate this threat have traditionally focused on regulation and enforcement, and there is a growing interest in campaigns to reduce consumer demand for wildlife products. We aimed to characterize these behavior-change campaigns and the evidence of their impacts. We searched peer-reviewed and grey literature repositories and over 200 institutional websites to retrieve information on demand-reduction campaigns. We found 236 campaigns, mainly in the grey literature. Since the 1970s, the number of campaigns increased, although for over 15% a start date could not be found. Asia was the primary focus, although at the national level the United States was where most campaigns took place. Campaigns most often focused on a single species of mammal; other vertebrates groups, with the exception of sharks, received limited attention. Many campaigns focused on broad themes, such as the wildlife trade in general or seafood. Thirty-seven percent of campaigns reported some information on their inputs, 98% on strategies, 70% on outputs, 37% on outcomes (i.e., changes in the target audience), and 9% on impacts (i.e., biological changes or threat reduction). Information on outcomes and impacts was largely anecdotal or based on research designs that are at a high risk of bias, such as pre- and postcampaign comparisons. It was unclear whether demand-reduction campaigns had direct behavioral or biological impacts. The lack of robust impact evaluation made it difficult to draw insights to inform future efforts, a crucial part of effectively addressing complex issues, such as the wildlife trade. If demand-reduction campaigns are to become a cornerstone of the efforts to mitigate the unsustainable trade in wildlife, conservationists need to adopt more rigorous impact evaluation and a more collaborative approach that fosters the sharing of data and insights. 相似文献
Conventional methods for water and wastewater treatment are energy-intensive, notably at the stage of coagulation–flocculation, calling for new strategies to predict pollutant reduction because the amount of energy consumed is related to how much of the pollutant is treated. Here we developed a model, named Bio-logic, inspired by ecosystems, where pollutants represent organisms, coagulants are food, and the wider environmental conditions are the living environment. Artificial intelligence was used to learn the biological behavior, which enabled an accurate prediction of the amount of pollutant reduction. Results show that pseudo-biological objects that have a strong affinity for biological food, such as turbidity, total phosphorus, ammonia nitrogen and the potassium permanganate index, induced a strong correlation, between measured pollutant consumption capacity and predicted values. For instance, R2 correlation coefficients are 0.97 for turbidity and 0.92 for the potassium permanganate index in the laboratory; and 0.99 for turbidity, 0.90 for total phosphorus, 0.75 for ammonia nitrogen and 0.63 for the potassium permanganate index in water treatment plants. Overall, our findings demonstrate that artificial intelligence can use the water Bio-logic model to predict the pollutant consumption capacity.
A serious fire and explosion accident that resulted in massive crude oil leakage and severe environmental pollution occurred on 16 July, 2010, in Dalian Port, China. To investigate the root cause of accident and conduct a wide-range investigation, desulfurizing agent JH02, which has a similar ingredient to the desulfurizing agent HD used in Dalian Port, and TS02 were employed in this study to determine the role of desulfurizing agents in the accident. The thermal behavior of crude oil, desulfurizing agents, and their mixtures was measured by using a C80 calorimeter. By using the calorimetric data, the kinetic parameters of the chemical reaction, such as activation energy, pre-exponential factor, and self-accelerating decomposition temperature of crude oil, as well as JH02, TS02, and their mixtures, were calculated and compared. The results indicated that the direct cause of the accident was the thermal runaway initiated by the increasing instability of the crude oil–desulfurizing agent mixture. Excess pressure in the oil pipeline triggered the physical explosion, but it alone was not enough to cause a serious damage. Furthermore, a stable desulfurizing agent such as TS02 could not ensure a safe desulfurizing process. The results of this study would benefit the safety management of desulfurizing processes during production and storage. 相似文献
The production of biodiesel is gaining momentum with the ever increasing demand of the fuel. Presently, limited literature is available with respect to well designed solid heterogeneous catalyst for biodiesel production considering all the characteristics, process and operation parameters. Hence, a study was conducted to design effective heterogeneous catalyst for biodiesel production. Further, the significant impact of different catalysts, different feed stock, various reaction conditions such as temperature, methanol oil molar ratio, catalyst concentrations and stability/inactivation of the catalysts, are detailed out for transesterification process of biodiesel production. Based on the studies it can be concluded that well designed heterogeneous catalyst can yield high throughput of biodiesel. 相似文献