微型测定法测定白醋中的总酸度

利用微型滴定法测定白醋中的总酸度,并对常量实验和微型实验的测定结果进行了比较分析。结果两种方法无显著性差异,F检验、t检验均在允许范围内,微型实验的准确度和精密度均达到常量实验的测定水平,完全满足化学分析要求,并且有效地节省了实验试剂,大大降低了实验成本。     

Development of a Quantitative Pasture Phosphorus Management Tool Using the SWAT Model1

Abstract: Assessment tools to evaluate phosphorus loss from agricultural lands allow conservation planners to evaluate the impact of management decisions on water quality. Available tools to predict phosphorus loss from agricultural fields are either: (1) qualitative indices with limited applicability to address offsite water quality standards, or (2) models which are prohibitively complex for application by most conservation planners. The purpose of this research was to develop a simple interface for a comprehensive hydrologic/water quality model to allow its usage by farmers and conservation planners. The Pasture Phosphorus Management (PPM) Calculator was developed to predict average annual phosphorus (P) losses from pastures under a variety of field conditions and management options. PPM Calculator is a vastly simplified interface for the Soil and Water Assessment Tool (SWAT) model that requires no knowledge of SWAT by the user. PPM Calculator was validated using 33 months of data on four pasture fields in northwestern Arkansas. This tool has been extensively applied in the Lake Eucha/Spavinaw Basin in northeastern Oklahoma and northwestern Arkansas. PPM Calculator allows conservation planners to take advantage of the predictive capacity of a comprehensive hydrologic water quality model typically reserved for use by hydrologists and engineers. This research demonstrates the applicability of existing water quality models in the development of user friendly P management tools.     

1957-2007年新疆天山山区气候变化对径流的影响

利用天山山区1957-2007年的气温、降水量及径流数据,借助非参数检验、小波变换等方法分析了天山山区气温、降水量及年径流量的变化趋势及多时间尺度相关。结果表明:玛纳斯河与塔里木河源流区年径流量、气温与降水量均呈显著增加趋势;在年代际上,塔里木河源流区气温存在11、18和22 a的主周期,降水量存在10、20与22 a的主周期;玛纳斯河气温在10与22 a处存在明显周期,降水量在20与22 a处周期性明显;同时,两源流区气温和降水量皆存在3~6 a的年际周期变化;塔里木河年径流量、气温和降水量的突变点分别发生在1993、1993和1992年,而玛纳斯河分别在1995、1988与1996年发生显著性突变;两流域源流区年径流量与气候因子存在显著的多时间尺度相关关系。     

过滤式碳纤维电极消毒效果比较与机理研究

过滤式电极消毒作为一种安全、高效的新型消毒技术备受关注, 然而目前使用的电极材料比较单一, 且稳定性和高效性难以兼备, 制约了该技术的设备化发展.本文采用过滤式消毒方式, 考察了几种高孔隙率的导电碳纤维毡的消毒效果.结果表明, 碳纤维毡电极具有优异的消毒能力, 活性碳纤维电极可在几伏的电压下使细菌死亡, 与传统电化学消毒相比, 电压降低了1~2个数量级.其中A-PCF(聚丙烯腈基活性碳纤维)电极在外接电压2 V, 水力停留时间2 s时即可对大肠杆菌菌液实现>6.5log的去除.当外接电压≤2 V时, 流出物中未检测到氯, pH保持不变, 排除了电化学产物的影响.A-PCF可作为过滤式电极消毒的优选电极材料.     

工业循环冷却水系统阻垢剂研究进展

本文简介了循环冷却水系统的应用现状和面临的问题．同时论述了冷却水系统结垢的成因和阻垢的机理,并介绍了阻垢剂的发展历程、研究进展及其特点。最后总结概括了未来阻垢剂的发展趋势。     

Health and environmental assessment of mercury exposure in a gold mining community in Western Mindanao, Philippines

The small-scale gold mining activities using mercury began in the late 1980s in Sibutad, Western Mindanao. It is located very near the Murcielagos Bay with tailing ponds directly discharging into bodies of water. This cross-sectional study aimed to determine the health and environmental effects of gold mining activities on the community. Residents were randomly selected and classified into two groups, namely, the directly exposed and indirectly exposed populations using a set inclusion criteria. Complete medical and laboratory examinations were performed. Environmental and biologic samples were collected for total mercury and methylmercury determinations. The results showed that the directly exposed group had significantly higher mean blood total mercury and methylmercury levels in comparison with the indirectly exposed population. Although there were no significant differences between hair total mercury and methylmercury levels, there was a trend for higher levels of these biomarkers among the directly exposed residents as compared with the unexposed group. The absence of statistically significant differences may be attributable to the small sample size. Ambient air quality monitoring for mercury exceeded the allowable levels. However, levels of mercury in drinking water and sediments were within allowable limits. Frequency of gastrointestinal complaints was significantly associated with elevated hair methylmercury levels (p=0.02). Also, there appears to be a trend towards higher blood total mercury levels and frequency of gastrointestinal complaints (p=0.09). An interesting finding in this study was the increasing incidence of elevated diastolic blood pressure with elevated hair total mercury levels (p=0.07). Mercury storage at home is a risk factor.     

UASB反应器常温下处理生活污水的中试研究

中试试验研究讨论了利用颗粒污泥接种的UASB反应器常温下处理生活污水的运行性能。在7～31℃温度范围内处理生活污水,考察了不同温度、不同负荷条件下反应器的处理效率,讨论了各参数对反应器运行的影响,为UASB反应器常温下处理生活污水提供理论和实践指导。     

磷石膏制硫酸钾中试研究

以湿法磷酸副产的磷石膏和工业品氯化钾为原料 ,采用两步法 ,常温常压下 ,在 5 0 0 0t a工业化装置中 ,生产符合国标ZBG2 10 0 6 89农用一级品硫酸钾。整个过程流程较简单 ,能耗低 ,投资省 ,基本无“三废”排放。钾的收率达70 %。工艺条件稳定 ,产品质量稳定。中试结果与小试有较好的重复性 ,放大效果好。