Sources, distribution, and risk assessment of organochlorine pesticides in Nairobi City, Kenya

The distribution and sources of organochlorine pesticides (OCPs) in air and surface waters were monitored in Nairobi City using triolein-filled semipermeable membrane devices (SPMDs). The SPMDs were extracted by dialysis using n-hexane, followed by cleanup by adsorption chromatography on silica gel cartridges. Sample analysis was done by GC-ECD and confirmed by GC–MS. Separation of means was achieved by analysis of variance, followed by pair-wise comparison using the t-test (p≤ 0.05). The total OCPs ranged between 0.018 – 1.277 ng/m³ in the air and <LOD – 1391.000 ng/m³ in surface waters. Based on the results, the means of Industrial Area, Dandora and Kibera were not significantly different (p≤ 0.05), but were higher (p≤ 0.05) than those of City square and Ngong’ Forest. The results revealed non-significant (p≤ 0.05) contribution of long-range transport to OCP pollution in Nairobi City. This indicated possible presence of point sources of environmental OCPs in the city. The water-air fugacity ratios indicated that volatilization and deposition played an important role in the spatial distribution of OCPs in Nairobi City. This indicated that contaminated surface waters could be major sources of human exposure to OCPs, through volatilization. The incremental lifetime cancer risks (ILCR) determined from inhalation of atmospheric OCPs were 2.3745  ×  10^?13 – 1.6845  ×  10^?11 (adult) and 5.5404  ×  10^?13 – 3.9306  ×  10^?11 (child) in the order: Dandora > Kibera > Industrial Area > City Square > Ngong’ Forest. However, these were lower than the USEPA acceptable risks, 10^?6 – 10^?4. This study concluded that atmospheric OCPs did not pose significant cancer risks to the residents.     

铁基质强化新型功能性化粪池高效处理黑水的试验

以铁基质生物载体为核心,将物理、生物和化学方法结合,对化粪池进行功能强化,实现黑水的原位深度处理.探究了溶解氧（DO）和碳氮比（C/N）等因素对黑水中污染物降解的影响,并在最佳运行参数下考察了氮素在系统中的转化机制.结果表明,当C/N为7.3~8.4时,好氧生物铁基质载体池DO为2.3~2.7mg/L时,系统氨氮（NH₄⁺-N）、总氮（TN） 、COD和总磷（TP）的平均去除率分别可达90.74%、85.81%、92.65%和95.78%;当进水C/N降至3.3~4.2时,系统NH₄⁺-N、TN、COD和TP的平均去除率仍可维持在81.16%、76.62%、93.87%和94.75%.铁基质生物载体内电解作用显著强化了化粪池内TN的脱除、COD的氧化和TP的固定.氮素转化机制分析表明,内电解与反硝化菌的耦合强化了反硝化作用,降低了反硝化过程对有机碳源的需求,强化了低C/N条件下TN、TP的脱除.     

解决对氨基二甲基苯胺光度法测定硫化物中的几个问题

介绍对氨基二甲基苯胺光度法测定硫化物方法中如何降低空白值,提高硫化钠溶液的稳定度以及提高酸化吹气回收率的原理和方法.     

梯度淋洗快速分析水中多环芳香烃

根据流动相极性理论，采用梯度淋洗一检测器编程方法检测多环芳烃，大大缩短了分析时间，并提高了灵敏度和精密度．为进一步定量分析提供了优良的途径。     

城市中水回用环境经济效益分析——以福州市洋里污水处理厂出水回用为例

以福州市洋里污水厂出水回用为例,运用费用效益分析方法计算得出静态投资回收期为2.64 a,远远小于基准投资回收期15~20 a。效益-费用比为1.44,大于1。结果表明,洋里污水厂达标出水作为中水回用的经济效益良好,并且具有明显的社会效益和环境效益。     

The effect of catch crops on sulphate leaching and availability of S in the succeeding crop on sandy loam soil in Denmark

Sulphate leaching losses may reduce the long-term possibility of maintaining the S supply of crops in low input farming systems. The ability of catch crops (Italian ryegrass (Lolium multiflorum Lam), winter rape (Brassica napus L.) and fodder radish (Raphanus sativus L.)) to reduce soil sulphate concentrations in autumn and make it available to a succeeding crop was investigated in 1996–1998 on sandy loam soil in Denmark. All catch crops reduced soil sulphate concentrations in the autumn compared to bare soil. Especially, the cruciferous catch crops had the ability to deplete efficiently soil sulphate levels and thus, reduce the sulphate leaching potential. The S uptake in aboveground catch crop was 8, 22 and 36 kg S per ha for ryegrass, winter rape and fodder radish, respectively. In the following spring, sulphate levels of the autumn bare soil were low in the top 0.5 m and a peak of sulphate was found at 0.75–1 m depth. In contrast, where a fodder radish catch crop had been grown, high sulphate levels were present in the top 0.5 m, but only small amounts of sulphate were found at 0.5–1.5 m depth. In spring barley (Hordeum vulgare L.), that followed catch crops, S concentrations at heading and maturity revealed that the availability of soil S increased following winter rape and fodder radish, whereas there were indications that following ryegrass, the S availability was reduced compared to bare soil. This initial study showed that catch crops have a high potential for reducing sulphate leaching and may be used to synchronise S availability with plant demand in a crop rotation.     

乙酸型顶极群落的内平衡与反馈调节机制研究

通过产酸脱硫反应器处理高浓度硫酸盐有机废水的连续流试验，从“动态”角度考察COD／SO4^2-比改变引起的pH值、氧化还原电位（ORP）、碱度（ALK）和末端产物（VFAs）等的变动及生态因子的叠加效应引发的优势种群变迁，分析了乙酸型顶极群落的稳定性及其发生定向性生态演替的规律，进而阐明了乙酸型顶极群落抵抗环境压力的内平衡与反馈调节机制，并指出乙酸型代谢和乙酸型顶极群落是产酸脱硫生态系统的典型特征。     

The curve of ion exchange ratio(%)-pH of the interaction between suspended particles with Cd(II) in the Yellow River

The curve of ion exchange ratio(%)-pH of the interactionbetween suspended particles with Cd(II) in the Yellow River wasstudied. The effects of lysine on this curve have been alsoinvestigated. The results showed that (1) Cadmium in Cd(OH)+ formin the suspended particles exchanges with the cations.The exchangeratio of Cd2+ is nearly at its greatest value in the range of pH(8.0-8.5) in natural aquatic system; (2) Ion exchange ratiodecreases as the concentration of Cd2+ raises from 8.9×10-6 mol/L to 2x8.9 x 10-6mol/L; (3) At the lysine concentration of 6.8x10-6 mol/L, it can promote the ion exchange ratio; (4) Adsorption of thesuspended particles to cadmium is weaker in seawater and Jin ShaRiver than in the Yellow River.     

渤海江豚组织中钠,钙,锶,镁,磷,钾的研究

１９９０年，作者于辽东湾采集了１０头江豚标本，分别测定了其骨骼、皮肤、肌肉、肝脏、肺、肾、心、胃、肠、胰、脾、肾上腺及生殖腺等１３种组织中Ｃａ、Ｓｒ、Ｍｇ、Ｐ、Ｋ、Ｎａ６种元素的含量，详细分析了骨骼及其他各组织中的Ｃａ／Ｍｇ值、Ｃａ／Ｋ值、Ｃａ／Ｐ值、Ｃａ／Ｎａ值和Ｃａ／Ｓｒ×１００值。结果表明，Ｃａ、Ｓｒ、Ｍｇ、Ｐ，Ｋ在骨骼中累积率最高，钾在肌肉中具有高累积，Ｓｒ、Ｃａ在肌肉中累积率最低；Ｍｇ累积率最低的组织是生殖腺，Ｐ累积率最低的组织是肠，而Ｋ在骨骼中，Ｎａ在肌肉中的累积率均高于其他组织。分析结果还显示，Ｃａ／Ｍｇ值最高的是骨骼，最低为肌肉，Ｃａ／Ｐ值最高的是骨骼，最低的是肌肉和胰脏，Ｃａ／Ｋ值最高为骨骼，最低为脾Ｃａ／Ｓｒ×１００值最高为肺、最低为肠，而Ｋ／Ｎａ值最高为肌肉，最低为骨骼，在骨中Ｃａ／Ｐ值大约为１，类同于猫和人类。     

Assessing the impact of pesticides on the environment

Pesticide use in agriculture can cause undesirable effects on humans and the natural environment. One of the objectives of integrated agriculture is the elimination or reduction of possible sources of environmental pollution such as pesticides. To achieve this objective, farmers need a method to assist them in estimating the environmental impact of pesticide use. This paper addresses a two-part question: what factors should be taken into consideration to assess pesticide environmental impact, and how can impact be quantified? As the environmental impact of a pesticide depends on its dispersion in the environment and on its toxicological properties, the literature on these topics is reviewed to address the first part of the question. To address the second part of the question, six recent approaches to assess the impact of pesticides on the environment are compared regarding choice, transformation and aggregation of input parameters. The use of simulation models to assess environmental impact is discussed.