Photooxidative removal of the herbicide Acid Blue 9 in the presence of hydrogen peroxide: modeling of the reaction for evaluation of electrical energy per order (EEO)

The present work deals with photooxidative removal of the herbicide, Acid Blue 9 (AB9), in water in the presence of hydrogen peroxide (H₂O₂) under UV light illumination (30 W). The influence of the basic operational parameters such as amount of H₂O₂, irradiation time and initial concentration of AB9 on the photodegradation efficiency of the herbicide was investigated. The degradation rate of AB9 was not appreciably high when the photolysis was carried out in the absence of H₂O₂ and it was negligible in the absence of UV light. The photooxidative removal of the herbicide was found to follow pseudo-first-order kinetic, and hence the figure-of-merit electrical energy per order (E_Eo) was considered appropriate for estimating the electrical energy efficiency. A mathematical relation between the apparent reaction rate constant and H₂O₂ used was applied for prediction of the electricity consumption in the photooxidative removal of AB9. The results indicated that this kinetic model, based on the initial rates of degradation, provided good prediction of the E_Eo values for a variety of conditions. The results also indicated that the UV/H₂O₂ process was appropriate as the effective treatment method for removal of AB9 from the contaminated wastewater.     

Nonformal environmental education: a case study with farmers in a town of the South Minas Gerais state,Brazil

Brazil is a central place in the international agricultural markets and this fact has been demanding environmentally oriented agricultural practices by Brazilian farmers and professionals involved in the agricultural market chain. A concise and structured questionnaire was applied to obtain the environmental perception of a group of Brazilian farmers in a town of the south Minas Gerais state, using herbicides as the topic for a case study. A highly variable opinion about taking the environment into account when choosing the most appropriate herbicide was found. Anyway, efficacy has been indicated as the most important factor when choosing an herbicide, followed by the environment and price. The outcomes from the questionnaires, i.e. the insufficient conception and importance given to environment when choosing the herbicide, motivated the creation of a teaching-learning model for the nonformal environmental education using the concept of socio-ecological resilience. This routine puts in practice the resilience thinking currently invoked as a major tool to achieve the conservation of the socio-ecological system, as well as it is complimentary to the outcome-oriented optimization for conservation theory. For the case study about farmers and the use of herbicides, we conclude that a complex reasoning and, ultimately, pro-environmental actions can be improved after experiencing the recommended model for environmental education.     

调水过程中城市内河含氮污染物负荷变化规律研究

针对我国城市内河污染日益严重的问题,以巢湖市老城区环城河为研究对象,拟定调水方案,进行调水试验。依据沿河水文水质情况,布设6个实时水质监测点,并将环城河概化为5个河段。应用测得的水文水质数据对各河段不同时间点的含氮污染物负荷进行估算,初步研究了各河段NH3-N、TN负荷量的变化规律。通过对比上下游各河段含氮污染物负荷去除效果,分析调水效果的影响因素,总结个别河段调水效果不佳的原因,提出4条优化意见。并结合实际情况,选取其中可行性较强的1条对其有效性进行实验验证。     

取代脲类除草剂光催化降解动力学比较

为研究取代脲类除草剂在TiO₂光催化降解过程中的动力学规律,以非草隆、异丙隆和利谷隆3种取代脲类除草剂为研究对象,通过Langmuir-Hinshelwood动力学模型对其TiO₂光催化降解动力学进行模拟,并系统探讨了催化剂用量、C₀(取代脲类除草剂的初始浓度)、溶液pH、温度、ROSs(活性氧物种)和电子捕获剂等的影响. 结果表明:非草隆、异丙隆和利谷隆的TiO₂光催化降解均符合假一级动力学模型,其动力学常数分别为0.082 8、0.068 7和0.095 4 min-1;取代脲类除草剂分子中的芳香环和脲桥上的取代基对降解速率常数的大小有明显的影响. ROSs试验表明,非草隆、异丙隆和利谷隆光催化降解过程中分别有91.6%、95.5%和86.8%的贡献来自·OH;而光生空穴和其他ROSs的贡献相对较小,并且电子捕获剂BrO₃-和S₂O₈2-对取代脲类除草剂的降解动力学有显著的促进作用.      

HERBICIDES AND DEGRADATES IN SHALLOW AQUIFERS OF ILLINOIS: SPATIAL AND TEMPORAL TRENDS1

ABSTRACT: During the fall of 2000, the occurrence was examined of 16 herbicides and 13 herbicide degradates in samples from 55 wells in shallow aquifers underlying grain producing regions of Illinois. Herbicide compounds with concentrations above 0.05 μg/L were detected in 56 percent of the samples. No concentrations exceeded regulatory drinking water standards. The six most frequently detected compounds were degradates. Water age was an important factor in determining vulnerability of ground water to transport of herbicide compounds. Unconsolidated aquifers, which were indicated to generally contain younger ground water than bedrock aquifers, had a higher occurrence of herbicides (73 percent of samples) than bedrock aquifers (22 percent). Temporal analysis to determine if changes in concentrations of selected herbicides and degradates could be observed over a near decadal period indicated a decrease in detection frequency (25 to 18 percent) between samplings in 1991 and 2000. Over this period, significant differences in concentrations were observed for atrazine (decrease) and total acetochlor (increase). The increase in acetochlor compound concentrations corresponds to an increase in acetochlor use during the study period, while the decrease in atrazine concentrations corresponds to relatively consistent use of atrazine. Changes in frequency of herbicide detection and concentration do not appear related to changes in land use near sampled wells.     

HERBICIDE AND NITRATE VARIATION IN ALLUVIUM UNDERLYING A CORN FIELD AT A SITE IN IOWA COUNTY,IOWA1

ABSTRACT: A hydrologic investigation to determine vertical and seasonal variation of atrazine, alachlor, cyanazine, and nitrate at one location and to relate the variation to ground-water movement in the Iowa River alluvium was conducted in Iowa County, Iowa, from March 1986 to December 1987. Water samples were collected at discrete intervals through the alluvial sequence from the soil zone to the base of the aquifer. Alachlor, atrazine, and cyanazine were detected most frequently in the soil zone but also were present in the upper part of the alluvial aquifer. Alachlor was detected sporadically, whereas, atrazine, cyanazine, and nitrate were present throughout the year. In the alluvial aquifer, the herbicides generally were not detected during 1986 and were present in detectable concentrations for only a short period of time in the upper 1.6 meters of the aquifer during 1987. Nitrate was present throughout the alluvium and was stratified in the alluvial aquifer. The largest nitrate concentrations were detected in the middle part of the aquifer. Nitrate concentrations were variable only in the upper 2 meters of the aquifer. Vertical movement of herbicides and nitrate in the soil correlated with precipitation and degree of saturation. A clay layer retarded vertical movement of atrazine but not nitrate from the soil layer to the aquifer. Vertical movement could not account for the chemical variation in the alluvial aquifer.     

环境水体中三嗪类除草剂的SPME-GCMS联用仪测定

文章研究了固相微萃取-气相色谱/质谱联用技术测定环境水体中的11种三嗪类除草剂的方法.选择了以聚二甲基硅氧烷(PDMS)/二乙烯苯(DVB)和聚丙烯(PA)作为涂层材料的两种不同固相微萃取纤维对11种除草剂的萃取能力进行比较,PDMS/DVB萃取效果较好.为了提高萃取效果,分别从pH、解吸温度、萃取时间、盐效应等方面优...     

直接进水样气相色谱法测定水和工业废水中乙腈、丙烯腈、苯胺及硝基苯

直接进水样气相色谱法测定水和工业废水中微量含氮有机污染物具有快速、简便、精确的特点。本法用５３０μｍ熔融石英毛细管柱分离,高灵敏度的氮磷检测器,进样１μｌ时检测限分别为０．４μｇ／Ｌ、０．４５μｇ／Ｌ、４μｇ／Ｌ、１０μｇ／Ｌ。这一灵敏度可满足排污监测及环境评价的要求。     

Progress in herbicide determination with the thylakoid bioassay

Chloroplast thylakoids are used as biological units to determine herbicides in different kinds of water samples as well as in aqueous extracts of compost, soil or food samples. The thylakoid bioassy shows clearly inhibition of fluorescence yield in the presence of photosystem II specific herbicides. Due to this method the ecotoxicological effect of samples with unknown pollutants can be tested fast and cost effective. It has been proven that all photosynthetic active compounds are recorded at the same time because only additive interactions occur. Therefore, the contamination level can be expressed as cumulative parameter for photosystem II active substances. Application was improved clearly by the addition of the radical scavenger sodium ascorbate to the isolation media and by a higher concentration of the measuring medium. A new data evaluation method is described yielding in a lower detection limit of 0.4 μg diuron/1. The guidelines for the quality of water for human consumption with an allowable concentration of pesticides in groups is 0,5 μg/1 [1,2] and can be controlled with the thylakoid bioassay without performing any preconcentration steps.     

甲黄隆,氯黄隆,苄嘧黄隆及其降解产物对蛋白核小球藻生长的效应

本文研究了甲黄隆、氯黄隆、苄嘧黄隆及其降解产物对蛋白核小球藻（Chlorellapyrenoidosa）的96h生长抑制急性毒性和化合物氮的生物可获得性。急性毒性试验表明:黄隆的毒性比其降解产物取代磺胺和氮杂环化合物大得多（EC_(50)相差2—3个数量级）,降解产物取代磺胺、均三嗪、取代嘧啶存在明显的低浓度促进生长现象,氮的生物可获得性试验表明:小球藻能有效利用低浓度取代磺胺、均三嗪、取代嘧啶化合物中的氮促进生长,促进程度:氯磺胺>苄磺胺≈二甲氧基嘧啶>甲磺胺>均三嗪。