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21.
This study uses knowledge discovery concepts to analyze large amounts of data step by step for the purpose of assisting in the formulation of environmental policy. We performed data cleansing and extracting from existing nation-wide databases, and used regression and classification techniques to analyze the data. The current water hardness in Kaohsiung, Taiwan contributes to the prevention of cardiovascular disease (CVD) but exacerbates the development of renal stones (RS). However, to focus on water hardness alone to control RS would not be cost effective at all, because the existing database parameters do not adequately allow for a clear understanding of RS. Analysis of huge amounts of data can most often turn up the most reliable and convincing results and the use of existing databases can be cost-effective.  相似文献   
22.
长江河口近岸水体自然净化作用及其初步评价   总被引:9,自引:1,他引:8  
按照水体的净化机理,结合长江口和上海滨岸带近岸水体的物理、化学和生物等因素的实际特征,对近岸水体的自然净化作用进行了阐述和分析。并在历史资料和实测资料基础上,就近岸水体的自然净化作用进行了评价。评价结果表明,因长江河口近岸水体存在较强的自然净化作用机制,近岸水体体的自然净化能力较强,环境容量较大,但由于污染物输入量的不断增加,部分岸段近岸水体的环境质量有逐渐下降的趋势;近岸水体的自然净化作用具有明显的季节性变化,长江口南岸水域洪水季节水体的自然净化作用比估水季节强,而杭州湾北岸水域的自然净化作用表现为相反的变化趋势,因此建议在近岸污水排放过程中应考虑近岸水体的净化能力,遵循水体的自然净化作用规律。  相似文献   
23.
湖北省雨涝灾害的风险评估与区划   总被引:8,自引:0,他引:8  
随着我国灾害科学研究的不断深入及经济建设的日益发展,从风险角度分析灾害已成为灾害分析的一种新视角,它有助于决策者进行灾害管理和制定减灾策略时有针对性地选择最优技术政策,防患于末然。雨涝灾害是湖北省最严重的气象灾害之一,据统计,湖北省平均每年受雨涝危害的农田面积为80.62万hm^2,成灾面积为47.07万hm^2,特别是20世纪80年代以来湖北省工农业生产重地江汉平原和鄂东雨涝事件明显增多,严重威胁和制约着我省国民经济持续稳定发展。依据自然灾害风险分析原理,在分析湖北省雨涝灾害孕灾环境、致灾因子、承灾体密度和经济发展水平及承灾体的抗灾能力的基础上,综合评价了湖北省雨涝灾害风险程度的地域差异,以能综合体现风险程度的风险指数作为指标,将湖北省雨涝灾害分为极重度、重度、中度和轻度四个风险区,并提出了相应的对策措施,为有关部门灾害管理和减灾决策制定提供了参考依据。  相似文献   
24.
Diadromous fish often enter freshwater directly from seawater via fish ladders or channels built in estuarine dams. The oxygen consumption rates (OCR) of glass eel, Anguilla japonica, were determined using an automatic intermittent flow respirometer under various salinity and temperature regimes to physiologically explain this direct movement. The endogenous rhythm of the OCR in wild glass eels, freshly collected from estuaries, was nearly synchronous with the tidal pattern at the estuarine collection site. When the salinity was changed from 20 psu (12°C) at a constant temperature to that of freshwater, the OCR of the glass eels decreased by 21.6±7.0% (mean ± SD) (P<0.05), showing a dampened rhythm for about 48 h. After this period of impediment, the glass eels resumed normal metabolic activity. Direct migration from seawater to freshwater under constant temperature would result in a severe physiological stress for these glass eels for about two days. When the glass eels were exposed to a cyclic change in water temperature of 2°C 26 h−1, as they encounter in estuaries, and then were introduced to freshwater abruptly, the OCR rhythm corresponded to the cyclic changes in water temperature after exposure to freshwater. Under these conditions, the mean OCR of the glass eels had a small difference before and after exposure to freshwater. These data explained how glass eels can directly move from sea water into the freshwater without any apparent metabolic stress in the estuaries showing cyclic change in water temperature (Δt=2°C).  相似文献   
25.
26.
Data collected from the five air-quality monitoring stations established by the Taiwan Environmental Protection Administration in Taipei City from 1994 to 2003 are analyzed to assess the temporal variations of air quality. Principal component analysis (PCA) is adopted to convert the original measuring pollutants into fewer independent components through linear combinations while still retaining the majority of the variance of the original data set. Two principal components (PCs) are retained together explaining 82.73% of the total variance. PC1, which represents primary pollutants such as CO, NO(x), and SO(2), shows an obvious decrease over the last 10 years. PC2, which represents secondary pollutants such as ozone, displays a yearly increase over the time period when a reduction of primary pollutants is obvious. In order to track down the control measures put forth by the authorities, 47 days of high PM(10) concentrations caused by transboundary transport have been eliminated in analyzing the long-term trend of PM(10) in Taipei City. The temporal variations over the past 10 years show that the moderate peak in O(3) demonstrates a significant upward trend even when the local primary pollutants have been well under control. Monthly variations of PC scores demonstrate that primary pollution is significant from January to April, while ozone increases from April to August. The results of the yearly variations of PC scores show that PM(10) has gradually shifted from a strong correlation with PC1 during the early years to become more related to PC2 in recent years. This implies that after a reduction of primary pollutants, the proportion of secondary aerosols in PM(10) may increase. Thus, reducing the precursor concentrations of secondary aerosols will be an effective way to lower PM(10) concentrations.  相似文献   
27.
On an upland moor dominated by pioneer Calluna vulgaris and with an understorey of mosses and lichens, experimental plots were treated with factorial combinations of nitrogen (N) at +0 and +20kg Nha(-1)yr(-1), and phosphorus (P) at +0 and +5kg Pha(-1)yr(-1). Over the 4-year duration of the experiment, the cover of the Calluna canopy increased in density over time as part of normal phenological development. Moss cover increased initially in response to N addition but then remained static; increases in cover in response to P addition became stronger over time, eventually causing reductions in the cover of the dominant Calluna canopy. Lichen cover virtually disappeared within 4 years in plots receiving +20kg Nha(-1)yr(-1) and also in separate plots receiving +10kg Nha(-1)yr(-1), but this effect was reversed by the addition of P.  相似文献   
28.
采用高温煅烧工艺,以工业生产次磷酸钠的废渣为原料,制备饲料级磷酸三钙,并对最佳工艺条件进行探讨。最佳工艺条件:煅烧温度600℃、煅烧时间20min。制得的饲料级磷酸三钙中磷的质量分数为16%~18%,符合Q/YHY01—2003《饲料级磷酸三钙》产品质量企业标准。  相似文献   
29.
When combined in the lining and covering of waste-containment facilities, soil and geosynthetic components protect the environment by acting as a hydraulic barrier. Equipment loading may significantly increase the tensile stress induced in geosynthetic components, leading to a potential stability problem. Large equipment loadings may also result in a localized circular slip surface during construction operations. New analytical method based on discrete element modelling is proposed for estimating the distribution of tensile force developed in the individual geosynthetic components of the lining system and for evaluating the safety factor of slope failure due to equipment loading. The analytical results of an example are presented to demonstrate the applicability of the analytical method for the lining system of a waste landfill. The analyses of the example show that equipment loading provide a substantial increase in the tensile forces of the geosynthetic components of a lining system and that the possibility of shallow failure due to equipment loading increases as the slope becomes steeper. This method is a useful tool for analysing the lining system of waste landfills with complex lining components.  相似文献   
30.
Stormwater runoff is now a major contributor to the pollution of coastal waters in the United States. Public agencies are responding by requiring stormwater monitoring to satisfy the National Pollutant Discharge Elimination System stormwater permit. However, studies to understand the utility of the current programs or to improve their usefulness have not yet been performed. In this paper, we evaluate the land-use-based program, the industrial stormwater permit program, and beach water-quality monitoring in the County of Los Angeles, California, to determine if the results will be helpful to planners and regulators in abating stormwater pollution. The utility of the program has been assessed based on the programs' ability to accurately estimate the emissions for different classes of land use. The land-use program appears successful, while the industrial monitoring program does not. Beach water-quality monitoring suffers from a lack of real-time monitoring techniques. We also provide suggested improvements, such as sampling method and time, and parameter selection.  相似文献   
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