The degradation of parathion and DDT in aqueous systems containing organic additives

Abstract

Laboratory studies were conducted to investigate some of the factors influencing pesticide degradation in‐ aqueous systems. Parathion added to natural water in ethanol, acetone or without organic solvent, was completely degraded within 2 wk. While most of the parathion was reduced to amino‐parathion when added in ethanol, no amino‐parathion was detected in the presence of acetone or when no solvent was added, suggesting that in the latter two cases the insecticide was aerobically degraded to other metabolites. No paraoxon was detected. When ethanol concentration was increased from 1% to 2 and 4%, the rate of parathion degradation was inversely related to the ethanol concentration. In the presence of glucose as a carbon source, approximately 50% of the parathion was reduced to aminoparathion. DDT degradation in natural water was more rapid when it was added in ethanol than when added in acetone. The only DDT metabolite detected was TDE, with about 36% conversion in presence of ethanol, and 20% when the DDT was added in acetone.     

某市南郊水源地土壤四氯化碳污染特征

含四氯化碳废水在排放的过程中沿排污渠侧壁和底部的渗漏对土壤造成污染.在对某市南郊受四氯化碳污染的水源地进行钻孔检测的过程中发现,土壤四氯化碳污染的特征:靠近排污沟的钻孔均检测出四氯化碳,而远离排污沟的钻孔则未检出;四氯化碳的垂向分布存在不连续性,且受降雨影响较大;大部分钻孔浅层土壤中基本未检测到四氯化碳,而在3 m以下的土层和基岩中检测到四氯化碳;抽水井的抽水行为导致抽水井附近土壤中四氯化碳明显高于其他钻孔点位检测结果.     

Metabolism of potassium bromate in rats I. In vivo studies

Potassium Bromate was administered orally to rats and its fate in the body was studied. The bromate was rapidly absorbed from the digestive tract and was partly excreted in the urine within two hours of administration. No bromate was detected in body organs or in the blood 24 hours after dosing. Excretion of bromate into the urine was proportional to the dose, except that at 2.5mg/kg or less no excretion was observed. The administration of bromate increased the bromide concentration in various organs and in urine.     

DO和pH值在短程硝化中的作用

在SBR反应器中对DO和pH值在短程硝化和半亚硝化过程中的作用进行试验研究,结果表明,控制低DO和适宜的pH值在短程硝化过程中起着重要的作用.本试验条件下,当DO为0.5～1.0 mg/L、pH值为7.5～8.0时,在SBR反应器中很容易实现短程硝化;当DO＞0.3 mg/L时,DO越低,出水NO2--N积累率越高;当pH值＞6.8时,不会影响系统NO2--N积累的稳定性.另外,研究结果还表明,通过控制DO和pH值可以实现半亚硝化.本试验条件下,当进水氨氮浓度为120 mg/L时,控制DO为0.3～0.4 mg/L可实现出水半亚硝化;当进水氨氮浓度为200 mg/L时,控制DO为0.5～0.6 mg/L或pH值为6.8也可以实现出水半亚硝化.     

Adsorption of phenol by bentonite

The potential of bentonite for phenol adsorption from aqueous solutions was studied. Batch kinetics and isotherm studies were carried out to evaluate the effect of contact time, initial concentration, pH, presence of solvent, and the desorption characteristics of bentonite. The adsorption of phenol increases with increasing initial phenol concentration and decreases with increasing the solution pH value. The adsorption process was significantly influenced by the solvent type in which phenol was dissolved. The affinity of phenol to bentonite in the presence of cyclohexane was greater than that in water and was lowest in the presence of methanol. Methanol was used to extract phenol from bentonite. The degree of extraction was dependent on the amount of phenol adsorbed by bentonite. X-ray diffraction analysis showed that the crystalline structure of bentonite was destroyed when cyclohexane was used. The ability of bentonite to adsorb phenol from cyclohexane decreased as the water to cyclohexane ratio was increased. Furthermore, hysteresis was observed in phenol desorption from bentonite in aqueous solutions. The equilibrium data in aqueous solutions was well represented by the Langmuir and Freundlich isotherm models. The removal of phenol from aqueous solutions was observed without surface modification.     

污泥活性炭强化SBR法处理垃圾渗滤液的实验研究

为了进一步处理垃圾渗滤液，试验采用污泥活性炭强化序批式间歇反应器（SBR）法进行处理，通过对比普通SBR法试验，得出投加污泥活性炭强化SBR法处理垃圾渗滤液的效果要远远高于普通SBR法。当污泥活性炭的投加量为1.2 g/L，容积负荷为0.5～1.5 kg BOD₅/(m³·d)时，进水1 h，曝气10 h，沉淀1.5 h，闲置1.5 h，处理效果最好，COD的去除率达到了85%，NH³-N的去除率达到了90%。     

Comparative studies on the biokinetics of Cd, Cr, and Zn in the green mussel Perna viridis and the Manila clam Ruditapes philippinarum

A kinetic approach was employed to determine the rates of metal uptake (Cd, Cr and Zn) from the dissolved phase and the rate constants of metal depuration in the mussel Perna viridis and the clam Ruditapes philippinarum. The effects of ambient metal concentration, salinity, and body size on the metal influx rate were examined. A linear positive relationship was observed between the metal influx rate and the metal concentration in ambient seawater. There was some evidence that Zn uptake was regulated by the bivalves in response to an increase in ambient Zn concentration. The uptake rate constant was highest for Zn and lowest for Cr in both bivalves, and was higher in mussels than in clams. The metal influx rate decreased by 1.6-1.8 times for the three metals when the salinity was increased from 15 ppt to 30 ppt. However, the effect of salinity on Zn influx in mussels was not statistically significant. A negative relationship of Cd and Zn influx rates with tissue dry weight was also found in both bivalves. Cr uptake in mussels was not significantly correlated with body size, but its uptake in clams was significantly correlated with body size. Metal concentration in ambient seawater appeared to be the most determining factor on metal uptake from the dissolved phase in both bivalves. The efflux rate constants of the three metals were within the range of 0.01-0.03 d-1, and were comparable between the mussels and the clams. Using a simple bioenergetic-based kinetic model, it was shown that both dissolved uptake and food ingestion can contribute to metal accumulation in the bivalves. However, Zn accumulation in the clam R. philippinarum was dominated by uptake from food ingestion. Metal partitioning in ingested food was found to be critical in affecting the relative importance of metal uptake from the dissolved phase and food source, primarily because of the large variability of this parameter in natural environments.     

Uptake and intracellular compartmentation of thorium in Saccharomyces cerevisiae

When Saccharomyces cerevisiae was cultured in the presence of thorium, the element was accumulated by the cells and was visible in electron micrographs as electron dense granules. When thorium was present during exponential growth, these granules were located mainly in the vacuole, with some present in the cytosol. Where thorium was present only during the stationary phase, there appeared to be greater thorium deposition in the cell wall than during exponential growth and some vacuolar deposits were also evident. Thorium uptake by exponential-phase cells was not stimulated by glucose and was thus independent of metabolic energy.     

林可霉素菌(Streptomyces lincolnensis)利用吡唑酮废水的研究

采用被吡唑酮废液驯化、分离、筛选后的林可霉素菌,并对其在摇瓶上利用吡唑酮废液中的硫酸铵发酵(7 d)生产林可霉素进行了研究。实验结果表明,废液加入培养基体积比都为1∶10,实验1中菌丝代谢和对照比正常,其中还原糖利用最快,在发酵后期为0.24 mg/L,林可霉素起步效价最低为2 100 IU/mL,与对照相比最后发酵效价降低了70 IU/mL;实验2发酵过程pH值偏低,全程为5.86～6.50,氨基氮代谢缓慢为40 mg/100 mL,最后林可霉素效价最低为4 480 IU/mL;实验3中废液在发酵进入48 h中后期的时候补入能促进菌丝体分泌,最后林可霉素为5 180 IU/mL,比对照发酵水平高出8.82%。可见实验3的实验设计有利于林可霉素菌利用吡唑酮废液生产林可霉素,为废物循环利用、变废为宝的可行性作了有意义尝试。     

Behavior of potassium in bread by ion chromatography

Public attention was aroused when mutagenicity was found in potassium bromate (KBrO₃) which has been used as an oxidizing agent in baking bread. Ion chromatography was found to be very useful for analyzing bromide and bromate ions in food. The residual condition of potassium bromate added to bread in the baking process was clarified.It was found that the residual rate of bromate ions in bread was approximately 30% at the added level of 100 μg/g, but it decreased markedly when the added levels went down. At 40 μg/g no residue was detected.     

褐煤活性炭吸附处理焦化废水

研究褐煤活性炭吸附处理焦化废水的性能，为褐煤活性炭用于废水处理提供理论依据和技术指导。以河南某气化厂的焦化废水为吸附原水，进行褐煤活性炭对酚吸附性能的静态和动态实验。静态实验表明，褐煤活性炭对酚的吸附性能符合弗兰德里希（Freundlich）吸附方程式。在室温条件下，对于150 mL焦化废水，当活性炭的用量为10 g，吸附反应时间为1 h，酚的去除率可达92%以上。动态实验研究表明，当进水酚浓度为3 800 mg/L，吸附1.5 h，活性炭的吸附容量可达21.38 mg/g。水处理的实验研究表明，利用褐煤制备的活性炭，对焦化废水具有良好的处理效果。     

Loss of HCH from surface soil layers under subtropical conditions

The loss of HCH (hexachlorocyclohexane) at an application rate of 25 kg ha(-1) was studied under field conditions from two surface soil layers, each of 7.5 cm, at two sites in Delhi. The soil at both sites was sandy loam type, with a pH of 8.2, and 0.8 to 1.0% organic matter content. At site 1, which was kept fallow and not watered, the upper 7.5-cm layer of soil initially lost HCH more rapidly than the lower layer. The half-life of the HCH in the upper and lower 7.5-cm layers was 21 and 41 days, respectively, and it was 26 days for the total HCH in the combined 15-cm soil layer. At site 2, which contained ornamental plants and was watered regularly, there was not much difference in the loss of HCH between the upper and lower layers. The half-life of HCH was 17 and 25 days for the upper and lower 7.5-cm layers, respectively, and it was 20 days for the total 15-cm soil layer, at this site. The loss was greatest initially at the sites, and was faster in wet soil than in dry soil.     

底物初始浓度对光合细菌产氢动力学特性的影响

实验研究了底物初始浓度对光合细菌产氢动力学特性的影响，并对光合细菌产氢得率和初始底物转化为氢气得率进行比较，分析底物初始浓度对光合细菌产氢代谢的影响，实验发现底物初始浓度为120 mmol/L时最适合光合细菌的产氢代谢，底物初始浓度达到140 mmol/L时，光合细菌主要进行生物量合成和产酸代谢，得到各浓度梯度下的最大生物量，但对产氢代谢产生抑制作用，表明最大生物量与最大的产氢能力之间不成正比关系及光合细菌产生CO2机制与产氢机制不同；光合细菌最大比产氢活性表现在对数生长期，最大生物量出现在稳定期。实验证明，光合细菌对数生长期受底物浓度影响大，底物浓度低，最大生物量所对应的时间相对较早，底物浓度增大，最大生物量所对应的时间相对延后。     

林可霉素菌（Streptomyces lincolnensis）利用吡唑酮废水的研究

采用被吡唑酮废液驯化、分离、筛选后的林可霉素菌,并对其在摇瓶上利用吡唑酮废液中的硫酸铵发酵（7 d）生产林可霉素进行了研究。实验结果表明,废液加入培养基体积比都为1∶10,实验1中菌丝代谢和对照比正常,其中还原糖利用最快,在发酵后期为0.24 mg/L,林可霉素起步效价最低为2 100 IU/mL,与对照相比最后发酵效价降低了70 IU/mL;实验2发酵过程pH值偏低,全程为5.86～6.50,氨基氮代谢缓慢为40 mg/100 mL,最后林可霉素效价最低为4 480 IU/mL;实验3中废液在发酵进入48 h中后期的时候补入能促进菌丝体分泌,最后林可霉素为5 180 IU/mL,比对照发酵水平高出8.82%。可见实验3的实验设计有利于林可霉素菌利用吡唑酮废液生产林可霉素,为废物循环利用、变废为宝的可行性作了有意义尝试。     

层次分析法与地理信息系统在农田土壤重金属污染评价中的应用

以《土壤环境质量标准》(GB 15618—1995)二级标准作为评价标准,采用以改进层次分析法确定权重的加权平均法对南京市郊典型蔬菜地的土壤重金属污染状况进行了评价。结果表明,研究区土壤中Cu、Pb、Cr的单因子污染指数平均值均小于1,含量超标率均不超过10.32%,而Cd的单因子污染指数平均值达2.15,含量超标率为84.13%,急需对该区土壤和受体做进一步的Cd污染深入调查或风险评估;研究区土壤重金属综合污染指数平均值为1.28,属玷污水平;利用ArcGIS 8.3软件进行土壤重金属污染的空间分布特征分析结果表明,研究区各元素的污染程度为Cd>Pb>Cu>Cr,各元素的污染格局较为相似,城市化活动对土壤污染贡献较大;研究区有81.16%的土壤重金属污染级别为玷污,3.78%处于本底级,15.06%处于安全级。     

Oxidative stress induced by HCH in Hydrilla verticillata (l.f.) Royle: modulation in uptake and toxicity due to Fe

The effect of hexachlorocyclohexane (HCH) singly and in combination with iron was studied on chlorophyll, malondialdehyde, cysteine, total -SH contents and potassium ion leakage in the plants of Hydrilla verticillata. The effect of HCH was also studied on glutathione (reduced and oxidised) content and superoxide dismutase activity. The results showed an increase in malondialdehyde content and potassium ion leakage with increase in HCH concentrations, however, the presence of Fe played a protective role. The chlorophyll content was decreased with increase in HCH concentrations and exposure period. However, the chlorophyll content at 2 and 5 microg ml(-1) was significantly higher in HCH-treated plants as compared to HCH + Fe after 168 h, showing protective role of Fe. The results showed significant increase up to 1 microg ml(-1) in cysteine content with increase in concentrations in both the treatments. The total -SH content was increased with increase in concentrations in both the treatments. In HCH-treated plants, non-significant change was noticed in reduced glutathione (GSH) content however, oxidised glutathione (GSSG) content was increased significantly after 168 h, indicative of oxidative stress. In addition, superoxide dismutase activity was increased non-significantly with increase in HCH concentrations. The accumulation of HCH singly and in presence of Fe was concentration- and duration-dependent. The accumulation of HCH was decreased in presence of Fe at higher concentrations. In contrast, the accumulation of Fe was increased in presence of HCH at higher concentrations. The results showed that malondialdehyde content and potassium ions leakage are the primary responses of toxicity.     

Pteris multifida Poir., a new arsenic hyperaccumulator: characteristics and potential

This paper reports a new arsenic hyperaccumulator, Pteris multifida Poir, a fern that grows widely in the southeast of China. The results show that the average arsenic content in the fronds was 1144.78 mg/kg, with a highest value of 2061 mg/kg. The average arsenic content in the roots was 692.7 mg/kg, and the average bioconcentration factor was 1.2, with a highest value of 1.78. The average translocation factor was 1.77, with a highest value of 3.13. The arsenic content in fronds was significantly correlated with the pH and the phosphorus available in the soil, but less correlated with the arsenic concentration in the soil. P.multifida Poir might accumulate the maximum arsenic in fronds when the soil-available phosphorus was 55 mg/kg and the soil pH was 8.34.     

复合植物床式人工湿地研究

本实验研究针对应用于面源污染控制的人工湿地中水生植物的选择和布置问题进行研究,通过对人工湿地动态运行实验的研究考察,发现床体中COD、TN降解规律,通过人工湿地栽种不同水生植物的各床体的COD去除效果比较实验和不同水生植物复氧性能比较实验,得出复氧性能最好的水生植物为芦苇,然后综合这三个实验,在传统的植物床系统基础上,提出更加有利于提高系统污水处理效率的改进形式:复合植物床式人工湿地。     

冬季沈阳市典型源排放PM10浓度分布模拟分析

选取沈阳市7个典型的大气污染源2006年12月～2007年2月的PM10排放浓度资料，利用CALPUFF对PM10浓度月平均分布做模拟分析。模拟结果分析表明：冬季月平均PM10浓度分布的范围与风场、地形有直接的关系。地势平坦、风速大时，污染物扩散范围大，污染物浓度小；地势不平、风速小时，污染物扩散范围小，污染物浓度大。1月份是沈阳市冬季月平均大气污染最严重的月份，污染物分布主要集中在市区的北部、东部和南部地区，东部地区大气污染最为严重。     

树脂-气升式环流生物反应器的脱氮性能

为了提高废水生物处理过程的脱氮性能,设计了树脂-气升式环流生物反应器,通过实验考察了该反应器连续抗氨氮冲击的能力,并验证了反应器中吸附铵离子的强酸阳离子树脂生物再生的可行性,分析了生物再生机理。结果表明,原水中铵离子之外的阳离子的存在是实现树脂生物再生的关键。