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731.
催化光度法测定地下水中超痕量锰 总被引:1,自引:0,他引:1
本文基于氨三乙酸为活化剂,Mn(Ⅱ)对KIO_4氧化次甲基氯的催化效应,建立了一个测定超痕量Mn(Ⅱ)的新方法.本法的检出限为1×10~(-10)g/ml,测定范围为0~40ng/25ml,用于地下水中痕量Mn(Ⅱ)的测定,结果令人满意. 相似文献
732.
Weidong Wang Jun Zheng Zhongqiong Wang Rongbin Zhang Qinghua Chen Xinfeng Yu Chengqing Yin 《环境科学学报(英文版)》2016,28(1):119-133
Shijiuyang Constructed Wetland(110 hm~2) is a drinking water source treatment wetland with primary structural units of ponds and plant-bed/ditch systems. The wetland can process about 250,000 tonnes of source water in the Xincheng River every day and supplies raw water for Shijiuyang Drinking Water Plant. Daily data for 28 months indicated that the major water quality indexes of source water had been improved by one grade. The percentage increase for dissolved oxygen and the removal rates of ammonia nitrogen, iron and manganese were 73.63%, 38.86%, 35.64%, and 22.14% respectively. The treatment performance weight of ponds and plant-bed/ditch systems was roughly equal but they treated different pollutants preferentially. Most water quality indexes had better treatment efficacy with increasing temperature and inlet concentrations. These results revealed that the pond–wetland complexes exhibited strong buffering capacity for source water quality improvement. The treatment cost of Shijiuyang Drinking Water Plant was reduced by about 30.3%. Regional rainfall significantly determined the external river water levels and adversely deteriorated the inlet water quality, thus suggesting that the "hidden" diffuse pollution in the multitudinous stream branches as well as their catchments should be the controlling emphases for river source water protection in the future. The combination of pond and plant-bed/ditch systems provides a successful paradigm for drinking water source pretreatment. Three other drinking water source treatment wetlands with ponds and plant-bed/ditch systems are in operation or construction in the stream networks of the Yangtze River Delta and more people will be benefited. 相似文献
733.
Wei Li Longjun Wang Fan Liu Xiaoliang Liang Xionghan Feng Wenfeng Tan Lirong Zheng Hui Yin 《环境科学学报(英文版)》2016,28(7):18-27
Al substitution in goethite is common in soils, and has strong influence on the structure and physicochemical properties of goethite. In this research, a series of Al-doped goethites were synthesized, and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and extended X-ray absorption fine structure (EXAFS) spectroscopy. The adsorption behavior of these samples towards PO43 − was also investigated. Characterization results demonstrated that increasing Al content in goethite led to a reduction in crystallinity, increase in specific surface area (SSA), and morphology change from needle-like to granular. Rietveld structure refinement revealed that the lattice parameter a remained almost constant and b slightly decreased, but c was significantly reduced, and the calculated crystal density increased. EXAFS analysis demonstrated that the Fe(Al)–O distance in the structure of the doped goethites was almost the same, but the Fe–Fe(Al) distance decreased with increasing Al content. Surface analysis showed that, with increasing Al content, the content of OH groups on the mineral surface increased. The adsorption of phosphate per unit mass of Al-doped goethite increased, while adsorption per unit area decreased owing to the decrease of the relative proportion of (110) facets in the total surface area of the minerals. The results of this research facilitate better understanding of the effect of Al substitution on the structure and properties of goethite and the cycling of phosphate in the environment. 相似文献
734.
735.
Comparative Analysis of Inundation Mapping Approaches for the 2016 Flood in the Brazos River,Texas 下载免费PDF全文
Jiaqi Zhang Yu‐Fen Huang Dinuke Munasinghe Zheng Fang Yin‐Phan Tsang Sagy Cohen 《Journal of the American Water Resources Association》2018,54(4):820-833
Accurate and timely flood inundation maps serve as crucial information for hydrologists, first‐responders, and decision makers of natural disaster management agencies. In this study, two modeling approaches are applied to estimate the inundation area for a large flooding event that occurred in May 2016 in the Brazos River: (1) Height Above the Nearest Drainage combined with National Hydrograph Dataset Plus (NHDPlus‐HAND) and (2) International River Interface Cooperative — Flow and Sediment Transport with Morphological Evolution of Channels (iRIC‐FaSTMECH). The inundation extents simulated from these two modeling approaches are then compared against the observed inundation extents derived from a Landsat 8 satellite image. The simulated results from NHDPlus‐HAND and iRIC‐FaSTMECH show 56% and 70% of overlaps with the observed flood extents, respectively. A modified version of the NHDPlus‐HAND model, considering networked catchment behaviors, is also tested with an improved fitness of 67%. This study suggests that NHDPlus‐HAND has the potential for real‐time continental inundation forecast due to its low computational cost and ease to couple with the National Water Model. Better performance of NHDPlus‐HAND can be achieved by considering the inter‐catchment flows during extreme riverine flood events. Overall, this study presents a comprehensive examination made of remote sensing compared with HAND‐based inundation mapping in a region of complex topography. 相似文献
736.
Yin Heliang Sun Tong Yao Lan Jiao Yan Ma Li Lin Lin Graff J Carolyn Aleya Lotfi Postlethwaite Arnold Gu Weikuan Chen Hong 《Environmental science and pollution research international》2021,28(30):40424-40430
Environmental Science and Pollution Research - Currently, 2019-nCoV has spread to most countries of the world. Understanding the environmental factors that affect the spread of the disease COVID-19... 相似文献
737.
Chuanbin Yin 《中国人口.资源与环境(英文版)》2017,15(2):157-166
In this study, we measure the environmental efficiency of western China in 2000–2014 by the super-efficiency slacks-based measure model which considers the undesirable outputs. The results show that the environmental efficiency of western China is low and rank behind in the national level. The environmental efficiency is lower than the traditional efficiency which reflects that the economic growth in 2000–2014 has paid high environmental costs. The difference between the traditional efficiency and environmental efficiency experienced “inverted U”-type trend change. The environmental efficiency of the western provinces presented differentiated developing trend and the differences between the western provinces were enlarging. The environmental efficiency of the western regions was not only lower than that in the eastern regions with a big gap but also lower than that in the central regions. Through the convergence test, we found that the environmental efficiency gap between the western and the eastern regions was gradually expanding; meanwhile, the environmental efficiency gap between the central and the western regions was narrowing. This paper also analyzes the determinants of environmental efficiency by the tobit model and then addresses. 相似文献
738.
<正>A model organism is a non-human species that is extensively studied to understand particular biological phenomena,with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms.模式生物是一类为了揭示特殊生物学现象而广泛采用的非人类种属,通过对模式生物物种进行的科学研究可以类推到同类或其他类别生物的某种具有普遍规律的生命现象。如今,模式生物的研究 相似文献
739.
Extensive research has examined the relationship between environmental management/performance and business performance but yielded no conclusive results. This paper makes two contributions to the literature. First, instead of focusing on one aspect, we try to compare using various types of cleaner production activities: low- and high-cost activities. Second, the study complements the existing literature which focuses on firms in developed countries with an analysis of firms in the Chinese manufacturing industry. In this paper, the relationship between cleaner production and business performance was analyzed using Structure Equation Model (SEM). We find an overall positive impact of cleaner production on firm's business performance. We also found that the cleaner production activities of low-cost scheme have a bigger contribution to financial performance compared to non-financial performance, while cleaner production activities of high-cost scheme have a greater contribution to non-financial performance, compared to financial performance. This study should be useful for firms that consider adopting cleaner production as well as stakeholders who aim to promote cleaner production. 相似文献
740.
浅议现代企业安全管理需要法治 总被引:1,自引:1,他引:0
简述了现代企业安全管理必须加强法制建设。只有逐步形成以法治为保障的安全管理模式,企业才能不断自我完善和发展。 相似文献