COMPARATIVE STUDY OF DROUGHT PREDICTION TECHNIQUES FOR RESERVOIR OPERATION1

ABSTRACT: Predicting the likelihood of a drought markedly enhances the efficiency of reservoir operations. This study applies the kriging method and time series analysis to predict inflows to Shihmen Reservoir in northern Taiwan. A subsequent reservoir operation simulation is employed to determine the drought lead time (DLT), the time before the onset of a drought. A more efficient reservoir operational strategy can be established with the aid of DLT and the probability of successful drought prediction (P s). Simulation results of reservoir operation over a period of three decades demonstrate that, at one month DLT, the kriging approach achieves 0.86 of P s for moderate droughts and 0.94 of P s for severe droughts. The kriging approach generally outperformed the time series approach in terms of DLT, P s of drought prediction, and the number of correctly predicted drought events.     

北京大气PM2.5中铅的同位素测定和来源研究

用石英滤膜连续采集北京2003-02～2003-03的12个PM_2.5样品,进行无机多元素、OC、EC和铅同位素丰度比的分析测定.对样品进行聚类分析,结合气象信息讨论了分组结果,描述了2003年春北京市的2个大气铅污染过程.2个污染过程均表现出铅含量高,²⁰⁶Pb/²⁰⁷Pb丰度比低的特点.Al、Ca、K等地壳元素的含量与Pb的含量负相关,表明土壤尘对铅的贡献不大.比较Pb、As、Zn、Se和Al、Ca等地壳元素含量的相关性,2个铅污染过程是由有色冶金排放和燃煤排放共同主导的.而02-28～03-02的铅污染过程中,燃煤排放贡献增大,有色冶金排放贡献下降.结果表明,汽油无铅化以后,北京市春季大气颗粒物中的铅主要来源于有色冶金排放与燃煤排放.     

新型胺化介孔炭的制备及其对Pb(II)的吸附

采用微波辅助磷酸活化制备了高中孔率蔗渣基介孔炭,并通过硝酸氧化和乙二胺聚合在其孔道内修饰了含氮多胺基团,探索了溶液浓度、温度、吸附剂剂量等对改性介孔炭的Pb(II)吸附性能、行为和热力学特性的影响.结果表明,蔗渣基介孔炭较宽的孔道结构可通过乙二胺缩水聚合反应在其表面接枝酰胺、仲胺等含氮基团;胺化改性增强化了介孔炭对水溶液中Pb(II)的固定作用,改性后介孔炭对Pb(II)的吸附量高达180mg/g,是改性前介孔炭的1.5倍;改性介孔炭对Pb(II)的去除率显著增加,对溶液浓度<60mg/L的Pb(II)去除率接近100%.等温吸附与热力学数据表明,胺化改性介孔炭对Pb(II)的吸附位能量存在差异化,吸附是自发的吸热反应过程,温度对铅(II)离子吸附有促进作用,化学作用在吸附过程中发挥了重要作用.     

土壤Pb暴露下赤子爱胜蚓(Eisenia fetida)的急性毒性和氧化应激反应

根据OECD试验指南,研究了人工土壤铅暴露下赤子爱胜蚓(Eisenia fetida)的急性毒性和氧化应激反应. 结果表明:铅暴露对赤子爱胜蚓14d的LC₅₀(半致死浓度)为2576.76mg/kg,95%置信区间为2388.42~2792.00mg/kg;铅暴露第1、7、14天赤子爱胜蚓的SOD(超氧化物歧化酶)活性,铅暴露第1、14天的POD(过氧化物酶)活性,铅暴露第14天的MDA(丙二醛)含量均与w(Pb)呈良好的剂量-效应关系,但CAT(过氧化氢酶)活性与w(Pb)未呈剂量-效应关系. 赤子爱胜蚓体内3种抗氧化酶对人工土壤铅污染响应的敏感程度为SOD>POD>CAT,SOD作为抗氧化系统的重要酶类可以更好地预测污染物对于赤子爱胜蚓的亚致死毒性.      

铅锌冶炼厂渣堆场周边土壤铅污染特征

金属冶炼过程留下的废渣经过雨水冲刷及渗滤液等的作用使残留在废渣中的重金属发生迁移转化,导致渣堆场下及周边土壤受到重金属污染。了解冶炼厂渣堆场下及周边土壤重金属污染状况对场地修复及土地利用规划均有重大意义。本研究调查了湖南某铅锌冶炼厂渣堆场0~4 km内三个采样区0~20 cm表层土壤及0~100 cm深度土壤中铅的污染状况,采用单项污染指数法进行铅污染评价,并分析了铅纵向迁移随深度变化和横向迁移随距离变化的分布特征。结果表明,铅锌冶炼厂渣堆场下及周边0~1 km范围内土壤受到了铅污染,渣堆场下、距渣堆场10 m处及1 km处表层土壤中重金属铅的质量分数分别可达775.25、645.33和309.80 mg·kg^-1,超过了当地土壤中铅的背景值,也超过了土壤二级质量标准甚至三级质量标准。三个采样区的铅污染指数分别为2.6、2.1及1.03,污染等级均为Ⅱ级,污染程度为轻度污染。三个采样区土壤中铅污染主要集中于0~20 cm土壤层中,铅的质量分数分别达775.25,645.33和309.80 mg·kg^-1,20~100 cm土壤层中铅的质量分数低于0~20 cm的,分别在88.48~120.96 mg·kg-1、235.01~380.16 mg·kg^-1及309.80~59.32 mg·kg^-1之间。渣堆场下土壤中的铅从0~20cm土壤层往下至20~100cm土壤层迁移量远小于距渣场10 m处及1 km处的。三个采样区表层0~20 cm土壤层中铅的变化规律为距渣堆场0 m（渣堆场下）〉距渣堆场10 m〉距渣堆场1 km〉距渣堆场4 km,质量分数随距离增加而降低。20~40 cm及40~60 cm土壤层中铅的变化规律为距渣堆场10 m〉距渣堆场1 km〉距渣堆场0 m处（渣堆场下）〉距渣堆场4 km,60~80 cm及80~100 cm土壤层的变化规律为距渣堆场10 m〉距渣堆场0 m处（渣堆场下）〉距渣堆场1 km〉距渣堆场4 km,铅的质量分数随距离的增加先升高后降低。     

Pb、Cd及其复合污染对紫茎泽兰生长及吸收富集特征的影响

外来植物紫茎泽兰（Eupatorium adenophorum）入侵我国西南地区并造成了严重的生态灾难,通过研究Pb、Cd及其复合污染对紫茎泽兰生长及吸收富集特征的影响,有助于从生态学角度为紫茎泽兰的综合防控提供依据。采用模拟Pb、Cd污染土壤培养法研究了不同浓度Pb、Cd及其复合污染作用下紫茎泽兰的生长响应及重金属吸收、富集和迁移特征变化。结果表明：低浓度的Pb、Cd对紫茎泽兰的生长有促进作用,高浓度则表现出一定的抑制作用,生物量,株高,根长均明显减少。紫茎泽兰体内Pb、Cd吸收量与污染土壤具有良好的相关性,随处理浓度增加明显增大,极端浓度Pb、Cd胁迫下紫茎泽兰各器官Pb、Cd积累量与对照相比显著增加,1000 mg·kg-1处理时紫茎泽兰根、茎、叶的Pb质量分数均分别高达603.69、568.31、598.85 mg·kg-1;100 mg·kg-1 Cd处理时其根、茎、叶的Pb、Cd累积量依次为165.21、93.59、152.79 mg·kg-1。说明紫茎泽兰对Pb、Cd具有较好吸收累积及转运能力,可作为重金属污染地区的一种理想的修复植物。     

Analysis of lead in tongkat Ali hitam herbal preparations in Malaysia

The DCA (Drug Control Authority), Ministry of Health, Malaysia implemented the phase three registration of traditional medicines on January 1st, 1992. As such, a total of 100 products in various pharmaceutical dosage forms of a herbal preparation obtained in Malaysia, containing tongkat Ali hitam, either single or combined preparations, were analyzed for the contamination of a heavy toxic metal, lead, using atomic absorption spectrophotometer, after performing a simple random sampling to enable each sample an equal chance of being selected in an unbiased manner. Results showed that 17% of these products contained 10.3–20.3?ppm of lead, and therefore, do not comply with the quality requirement for traditional medicines in Malaysia. The quality requirement for traditional medicines in Malaysia is not exceeding 10?ppm for lead. Out of these 17 products, 7 products have been registered with the DCA, Malaysia whilst the rest, however, have not registered with the DCA, Malaysia. Although this study showed that 83% of the products complied with the quality requirement for traditional medicines in Malaysia pertaining to lead, however, they cannot be assumed safe from lead contamination because of the risk of batch-to-batch variability.     

Prevalence of anaemia among children living in five communities in and near Karachi,Pakistan

The primary objectives of this research were to estimate the prevalence of anaemia and low haematocrit among preschool children living in Karachi. Through a geographically stratified design, 349 children aged 36–60 months were selected, from five communities in and near Karachi. Blood samples were drawn from children and a questionnaire was administered to evaluate various demographic and socioeconomic characteristics. Chi-square test and multiple logistic regression procedures were used to compare the prevalence of anaemia and low haematocrit among various strata. The overall prevalence of anaemia and low haematocrit were 55.9 and 48.4%, respectively. Children living in the rural community had the highest prevalence of anaemia (78.7%) and low haematocrit (63.8%). Children aged 36–48 months had also higher prevalence of anaemia and low haematocrit. Children's nutritional status was significantly associated with both anaemia and low haematocrit. We recommend appropriate interventions to reduce the burden of these conditions in Pakistan.     

Lead-induced alterations in protein-deficient rat liver–role of zinc

This study was designed to determine the protective effects of zinc (Zn) using liver marker enzymes in the serum and liver along with hepatic elemental profile in lead (Pb)-treated protein-deficient (PD) Sprague–Dawley male rats. Zn in the form of zinc sulfate at a dose of 227?mg?L^?1 in drinking water was administrated to control, PD as well as Pb-treated PD rats for 8 weeks. Pb treatment was given orally as lead acetate at a dose level of 100?mg?kg^?1 body weight to control and PD rats. The effects of different treatments were studied on the activities of enzymes that included alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum. The status of different elements (Cl, K, Mn, Fe, Cu, Zn, Se, Rb, Pb) in liver was also studied. Rats given PD diet and Pb showed significant inhibition in serum ALP activity associated with significant elevation in both AST and ALT activities. Serum ALP activity showed a significant inhibition week 1 until week 8 in Pb-treated PD rats. In contrast, serum AST activity was elevated both at 3 and 8 weeks while serum ALT activity was elevated at 8 weeks in Pb-treated PD rats. Pb treatment to PD rats elevated hepatic ALP, AST and ALT activities but depressed hepatic AST. Zn supplementation to Pb-treated PD rats restored the altered enzyme activities. The levels of K, Fe, Cu, Zn, Se and Rb were altered in protein deficiency. Furthermore, treatment with Pb to these animals depressed the Cu levels. Zn treatment to Pb-treated PD animals tended to restore the levels of altered elements. Hence, the present study clearly suggests that Zn plays an important role in regulating the liver marker enzymes and essential elements under conditions of Pb toxicity and protein deficiency.     

Experimental investigations of five different mosses on accumulation capacities of Cu,Pb and Zn

Uptake of Pb, Cu and Zn by different epiphytic moss species Floribundaria floribunda (Doz. &; Molk.) Fleisch., Taxiphyllum giraldii (C. Muell.) Fleisch. and Thuidium sparsifolium (Mitt.) Jaeg., an epilithic moss Thuidium delicatulum (L.) Mitt. and a leafy liverwort Ptychanthus striatus (Lehm. &; Linderb.) Nees. was studied experimentally. The plant bodies were treated with single metal and mixed metal solutions of Pb(NO₃)₂, CuCl₂ and ZnCl₂ at different concentrations ranging from 10^?10 to 10^?2 mol L^?1. Higher uptake of Pb, Cu and Zn by T. giraldii, T. sparsifolium and P. striatus than by F. floribunda and T. delicatulum was shown in both treatments. Compared with the single metal treatment, the uptake of Zn was very low at higher concentrations in the mixed metal treatment. A slight depletion of Zn was noticed in the long-term exposure. Leaching of naturally accumulated Zn from the mosses and leafy liverwort was also observed when treated with higher concentrated (10^?4, 10^?2 mol L^?1) Pb(NO₃)₂ and CuCl₂ solutions. Similarly, the leaching of naturally accumulated Cu was observed in leafy liverwort P. striatus with 10^?2 mol L^?1 Pb(NO₃)₂ and ZnCl₂ treatments. However, insignificant changes were observed on naturally accumulated Pb and Cu in mosses. From these experiments, the epiphytic mosses T. giraldii and T. sparsifolium, which have high Cation exchange capacity and large leaf surface area, have been found to be suitable for assessing heavy metal concentration in a moderately or slightly contaminated environment.