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排序方式: 共有108条查询结果,搜索用时 15 毫秒
1.
Pesticide transport models commonly assume first-order pesticide degradation kinetics for describing reactive transport in soil. This assumption was assessed in mini-column studies with associated batch degradation tests. Soil mini-columns were irrigated with atrazine in two intermittent steps of about 30 days separated by 161 days application of artificial rain water. Atrazine concentration in the effluent peaked to that of the influent concentration after initial break-through but sharply decreased while influx was sustained, suggesting a degradation lag phase. The same pattern was displayed in the second step but peak height and percentage of atrazine recovered in the effluent were lower. A Monod model with biomass decay was successfully calibrated to this data. The model was successfully evaluated against batch degradation data and mini-column experiments at lower flow rate. The study suggested that first-order degradation models may underestimate risk of pesticide leaching if the pesticide degradation potential needs amplification during degradation.  相似文献   
2.
UV-H_2O_2联用工艺去除水中阿特拉津的研究   总被引:2,自引:0,他引:2  
采用间歇式反应器考察了UV-H2O2高级氧化技术去除水中阿特拉津的效果及其影响因素,并进行了相关的反应动力学研究。结果表明,在pH值6.9,阿特拉津初始浓度500μg/L,紫外辐照强度172μW/cm2时,H2O2投加量50mg/L,反应10min后,阿特拉津的去除率90%。UV-H2O2联用工艺对阿特拉津的降解符合一级反应动力学。H2O2在该联用工艺降解阿特拉津中具有双重作用,一方面,当H2O2投加量较小时,一级反应速率常数随H2O2投加量的增加基本呈现线性增加的趋势;另一方面,当H2O2浓度增加到一定程度(90mg/L)后,阿特拉津的降解速率随H2O2浓度的变化已不明显,而H2O2浓度为102mg/L时,则出现了抑制作用。  相似文献   
3.
Biotransformation studies of atrazine, metolachlor and evolution of their metabolites were carried out in soils and subsoils of Northern Greece. Trace atrazine, its metabolites and metolachlor residues were detected in field soil samples 1 year after their application. The biotransformation rates of atrazine were higher in soils and subsoils of field previously exposed to atrazine (maize field sites) than in respective layers of the field margin. The DT50 values of atrazine ranged from 5 to 18 d in the surface layers of the adapted soils. DT50 values of atrazine increased as the soil depth increased reaching the value of 43 d in the 80-110 cm depth layer of adapted soils. Metolachlor degraded at slower rates than atrazine in surface soils, subsoils of field and field margins with the respective DT50 values ranging from 56 to 72 d in surface soils and from 165 to 186 d in subsoils. Hydroxyatrazine was the most frequently detected metabolite of atrazine. The maximum concentrations of metolachlor-OXA and metolachlor-ESA were detected in the soil layers of 20-40 cm depth after 90 d of incubation. Principal Component Analysis (PCA) of soil Phospholipid Fatty Acids (PLFAs), fungal/bacterial and Gram-negative/Gram-positive ratios of the PLFA profiles revealed that the higher biotransformation rates of atrazine were simultaneously observed with the abundance of Gram-negative bacteria while the respective rates of metolachlor were observed in soil samples with abundance of fungi.  相似文献   
4.
Abstract

Greenhouse studies were conducted to determine the influence of waste‐activated carbon (WAC), digested municipal sewage sludge (DMS), and animal manure on herbicidal activity of atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐trazine] and alachlor [2‐chloro‐2’,6'‐diethyl‐N‐(methoxymethyl)acetanilide] in a Plainfield sandy soil. Amendments generally reduced bioactivity against oat (Avena sativa L.) and Japanese millet (E. crus‐galli frumentacea). The extent to which herbicide phytotoxicity was inhibited depended upon the application rate and the kind of soil amendment. WAC, applied at the loading rate of 2.1 mt C/ha, showed a significant inhibitory effect on both herbicides. In DMS‐ and manure‐amended soil, the reduction of atrazine activity was not significant at the rate of 8.4 mt C/ha, but reduction of alachlor activity was significant at the rate of 4.2 mt C/ha. Despite inhibition of herbicidal activity, the ED50 of atrazine and alachlor was below 2 ppm in most of the amendment treatments. Before adopting carbon‐rich waste amendments as management practices for controlling pesticide leaching in coarse‐textured soils, further studies are needed to characterize how alterations in sorption, leaching and degradation may affect herbicidal activity.  相似文献   
5.
Atrazine, a widely used herbicide, is increasing the agricultural production effectively, while also causing great environmental concern. Efficient atrazine-degrading bacterium is necessary to removal atrazine rapidly to keep a safe environment. In the present study, a new atrazine-degrading strain ZXY-1, identified as Pseudomonas, was isolated. This new isolated strain has a strong ability to biodegrade atrazine with a high efficiency of 9.09 mg/L/hr.Temperature, p H, inoculum size and initial atrazine concentration were examined to further optimize the degradation of atrazine, and the synthetic effect of these factors were investigated by the response surface methodology. With a high quadratic polynomial mathematical model(R~2= 0.9821) being obtained, the highest biodegradation efficiency of 19.03 mg/L/hr was reached compared to previous reports under the optimal conditions(30.71°C, pH 7.14, 4.23%(V/V) inoculum size and 157.1 mg/L initial atrazine concentration).Overall, this study provided an efficient bacterium and approach that could be potentially useful for the bioremediation of wastewater containing atrazine.  相似文献   
6.
Atrazine biodegradation by immobilized pure and mixed cultures was examined. A pure atrazine-degrading culture, Agrobacterium radiobacter J14a (J14a), and a mixed culture (MC), isolated from an atrazine-contaminated crop field, were immobilized using phosphorylated-polyvinyl alcohol (PPVA). An existing cell immobilization procedure was modified to enhance PPVA matrix stability. The results showed that the matrices remained mechanically and chemically stable after shaking with glass beads over 15 days under various salt solutions and pH values. The immobilization process had a slight effect on cell viability. With the aid of scanning electron microscopy, a suitable microstructure of PPVA matrices for cell entrapment was observed. There were two porous layers of spherical gel matrices, the outside having an encapsulation property and the inside containing numerous pores for bacteria to occupy. J14a and MC were immobilized at three cell-to-matrix ratios of 3.5, 6.7, and 20 mg dry cells/mL matrix. The atrazine biodegradation tests were conducted in an aerobic batch system, which was inoculated with cells at 2,000 mg/L. The tests were also conducted using free (non-immobilized) J14a and MC for comparative purpose. The cell-to-matrix ratio of 3.5 mg/mL provided the highest atrazine removal efficiency of 40–50% in 120 h for both J14a and MC. The free cell systems, for both cultures, presented much lower atrazine removal efficiencies compared to the immobilized cell systems at the same level of inoculation.  相似文献   
7.
阿特拉津在土壤中的生物降解研究   总被引:25,自引:0,他引:25  
运用恒温培养法研究了阿特拉津在河北省白洋淀地区农田土壤中的生物降解动力学,并从中分离鉴定了土壤中降解阿特拉津的优势菌种,研究结果表明,该土壤对阿特拉津具有一定的降解能力,非生物+生物的降解、非生物降解和生物降解的速率分别为0.0262d^-1,0.005548d^-1和0.008194d^-1,半衰期分别为26d,125d和85d,发现土壤中降解阿特拉津的优势菌种为蜡状芽孢杆菌(Bacillus  相似文献   
8.
O3/H2O2降解Atrazine效能研究   总被引:1,自引:0,他引:1  
利用O3/H2O2降解莠去津,对氧化产物进行了色谱分析,以评价该体系降解莠去津效能.莠去津初始浓度2 mg/L,7.5mg/L的O3单独氧化去除率为27.2%;相同O3投量下,H2O2/O3摩尔比0.75时,5 min莠去津的去除率最高可达96.5%,表明H2O2/O3体系对莠去津的去除效果良好,降解速度快.以离子色谱对产物的离子进行分析,莠去津浓度下降的同时,硝酸根和氯离子浓度增高.GC-MS检测的产物和对LC-MS谱图的分析表明,有机产物中存在脱乙基、脱异丙基和脱氯莠去津,说明H2O2/O3并不能彻底氧化莠去津,因此工程中作为主要去除单元或突发性污染事件的应急手段可能还需要与活性炭等单元联用.  相似文献   
9.
水中阿特拉津的气相色谱法测定   总被引:2,自引:1,他引:1  
采用正已烷液液萃取方法,萃取液经320m石英弹性毛细管柱分离,用电子捕获检测器(ECD)检测水中阿特拉津,得到了良好的分离效果和较高的灵敏度及精密度,达到GB3838—2003《地面水环境质量标准》中的要求。  相似文献   
10.
To examine the link between corn agriculture and the observed decline of the endangered southern bell frog (SBF), the effects of two corn crop pesticides on larval growth and development were investigated. Tadpoles were exposed to terbufos sulfone (10 μg/L), a major breakdown product of the insecticide terbufos, and the herbicide atrazine (25 μg/L) individually and as a mixture until the completion of metamorphosis. Atrazine did not interact synergistically with terbufos sulfone or result in significant effects on growth and development alone, although there was some indication of accelerated metamorphosis in the pilot study. Terbufos sulfone alone and as a mixture (terbufos/atrazine) significantly slowed larval development and ultimately delayed metamorphosis. The observed developmental effects from an environmentally relevant concentration of terbufos sulfone indicates a risk posed by this persistent degradation product to the endangered SBF, which breeds and develops in the rice bays adjacent to corn fields treated with pesticides.  相似文献   
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