Optimal conditions for chlorothalonil and dissolved organic carbon in horizontal subsurface flow constructed wetlands

The most efficient system of horizontal subsurface flow constructed wetlands (HSSFCW) for removing dissolved organic carbon (DOC) in the presence of chlorothalonil pesticide (CLT) present in synthetic domestic wastewater was determined using the macrophyte Phragmites australis. Two concentrations of CLT (85 and 385 μg L^?1) and one concentration of glucose (20 mg L^?1) were evaluated in four pilot scale horizontal surface flow constructed wetlands coupled with two sizes of silica gravel, igneous gravel, fine chalky gravel (3.18–6.35 mm), coarse gravel (12.70–25.40 mm) and two water surface heights (20 and 40 cm). For a month, wetlands were acclimated with domestic wastewater. Some groups of bacteria were also identified in the biofilm attached to the gravel. In each treatment periodic samplings were conducted in the influent and effluent. Chlorothalonil was quantified by gas chromatography (GC-ECD m), DOC by an organic carbon analyzer and bacterial groups using conventional microbiology in accordance with Standard Methods. The largest removals of DOC (85.82%–85.31%) were found when using fine gravel (3.18–6.35 mm) and the lower layer of water (20 cm). The bacterial groups quantified in the biofilm were total heterotrophic, revivable heterotrophic, Pseudomonas and total coliforms. The results of this study indicate that fine grain gravel (3.18–6.35 mm) and both water levels (20 to 40 cm) can be used in the removal of organic matter and for the treatment of agricultural effluents contaminated with organo-chloride pesticides like CLT in HSSFCW.     

气相色谱法测定地表水中百菌清和菊酯类农药

采用正己烷萃取地表水中的百菌清和6种菊酯类农药,通过毛细管气相色谱法-电子捕获检测器(GC-ECD)定性定量。供试农药的线性范围:百菌清为10.0μg/L～200μg/L,6种菊酯类为50.0μg/L～1 000μg/L;方法检出限分别为:百菌清0.054μg/L,甲氰菊酯0.62μg/L,三氟氯氰菊酯0.68μg/L,氯菊酯0.40μg/L,氯氰菊酯0.65μg/L,氰戊菊酯0.78μg/L,溴氰菊酯0.15μg/L;对地表水样品3个质量浓度水平的平均加标回收率为91.3%～118%,6次平行测定的RSD<5%。     

A comparison of mixture toxicity assessment: examining the chronic toxicity of atrazine, permethrin and chlorothalonil in mixtures to Ceriodaphnia cf. dubia

Pesticides predominantly occur in aquatic ecosystems as mixtures of varying complexity, yet relatively few studies have examined the toxicity of pesticide mixtures. Atrazine, chlorothalonil and permethrin are widely used pesticides that have different modes of action. This study examined the chronic toxicities (7-d reproductive impairment) of these pesticides in binary and ternary mixtures to the freshwater cladoceran Ceriodaphnia cf. dubia. The toxicity of the mixtures was compared to that predicted by the independent action (IA) model for mixtures, as this is the most appropriate model for chemicals with different modes of action. Following this they were compared to the toxicity predicted by the concentration addition (CA) model for mixtures. According to the IA model, the toxicity of the chlorothalonil plus atrazine mixture conformed to antagonism, while that of chlorothalonil and permethrin conformed to synergism. The toxicity of the atrazine and permethrin mixture as well as the ternary mixture conformed to IA implying there was either no interaction between the components of these mixtures and/or in the case of the ternary mixture the interactions cancelled each other out to result in IA. The synergistic and antagonistic mixtures deviated from IA by factors greater than 3 and less than 2.5, respectively. When the toxicity of the mixtures was compared to the predictions of the CA model, the binary mixture of chlorothalonil plus atrazine, permethrin plus atrazine and the ternary mixture all conformed to antagonism, while the binary mixture of chlorothalonil plus permethrin conformed to CA. Using the CA model provided estimates of mixture toxicity that did not markedly underestimate the measured toxicity, unlike the IA model, and therefore the CA model is the most suitable to use in ecological risk assessments of these pesticides.     

五种农药对土壤转化酶活性的影响

测定了5种农药(多菌灵、百菌清、多菌灵-百菌清混剂、吡虫啉、氯氰菊酯)对长春市郊大棚土壤转化酶活性的影响,对农药作用下的大棚土壤与农田土壤的转化酶活性进行了比较研究.结果表明,百菌清、百菌清-多菌灵混剂、氯氰菊酯在实验浓度范围内(0.1～50mg/g)明显抑制土壤转化酶活性;多菌灵、吡虫啉浓度低于0.1mg/g时,对转化酶有激活作用,而浓度高于0.5mg/g时抑制转化酶活性;百菌清和多菌灵联合使用,会使农药毒性明显增强;不同农药对大棚土壤、农田土壤转化酶活性的影响不同.     

Nylon 6,6 modified screen printed carbon electrodes as electrochemical sensors for rapid chlorothalonil determination in water samples using differential pulse cathodic stripping voltammetry

A newly developed electrochemical sensor for chlorothalonil based on nylon 6,6 film deposited onto screen printed electrode (SPE) with electrochemical modulation of pH at the electrode/solution interface was studied for the first time. Differential pulse cathodic stripping voltammetry (DPCSV) was used to carry out the electrochemical and analytical studies. Experimental parameters such as accumulation potential, initial potential, accumulation time and pH of Britton-Robinson buffer have been optimized. Chlorothalonil gave optimum analytical signal in a medium of 0.04?M Britton-Robinson buffer at pH 6.0. A well-defined reduction peak was observed, at E_p= ?0.851 and ?0.938?V vs. Ag/AgCl (3.0?M KCl) for both bare SPE and modified SPE, respectively. The peak currents of modified SPE were significantly increased as compared to bare SPE. At the modified SPE, a linear relationship between the peak current and chlorothalonil concentration was obtained in the range from 0.1 to 2.8?×?10^?6?M with a detection limit of 1.53?×?10^?8?M (S/N=?3). The practical applicability of the newly developed method has been demonstrated on analyses of real water samples. The newly developed sensor shows good reproducibility with RSD of 3.92%. The nylon 6,6 modified SPE showed itself as promising sensor with good selectivity for chlorothalonil determination.     

在线固相萃取-双梯度高效液相色谱测定环境水体中痕量甲萘威和百菌清

利用双梯度液相色谱仪与固相萃取技术结合,建立了一种在线固相萃取-高效液相色谱同时测定环境水体中甲萘威和百菌清的方法。在取样2.5 mL时,甲萘威和百菌清的检出限分别为0.6 ng/mL和0.4 ng/mL。以20 μg/L标准溶液作为样品溶液,连续进样5针,测定峰面积,计算相对标准偏差(RSD),结果甲萘威的RSD为1.45%,百菌清的RSD为1.20%,符合方法学要求。     

Determination of chlorothalonil residues in coffee

Coffee beans were treated with the fungicide chlorothalonil (2,4,5,6‐tetrachloro‐1,3‐benzene‐dicarbonitrile) and the residues were determined by high‐performance liquid Chromatograph (HPLC). Several techniques including Soxhlet extraction (SE), microwave‐assisted extraction (MAE) and accelerated solvent extraction (ASE) were compared for the extraction of residues. A column clean‐up procedure was developed to remove the co‐extractives in the extract before HPLC analysis. The overall mean recoveries from extracts obtained by SE, MAE and ASE were 89.2 ±3.9, 88.4 ±1.9 and 82.8 ±0.3, respectively. The results show that MAE followed by HPLC is a viable alternative to the commonly used SE and gas Chromatographic analysis for the determination of chlorothalonil in coffee.     

液液萃取-气相色谱-质谱法同时测定饮用水中的酞酸酯、百菌清和联苯胺

建立了液液萃取-气相色谱-质谱（LLE -GC/MS）同时测定饮用水中的6种酞酸酯类化合物、百菌清和联苯胺的方法。选用3种有机溶剂进行萃取，筛选出回收率高、操作简单的前处理方法，萃取后经气相色谱-质谱分析。方法表明：8种物质线性良好，相关系数为0．9978～0．9995，用二氯甲烷萃取回收率最佳，回收率在90．1％～118％之间，相对标准偏差在0．24％～7．21％之间。