Atrazine and Alachlor Inputs to Surface and Ground Waters in Irrigated Corn Cultivation Areas of Castilla-Leon Region, Spain

The inputs of atrazine and alachlor herbicides to surface and ground waters from irrigated areas dedicated to corn cultivation in the Castilla-León (C-L) region (Spain) as related to the application of both herbicides were studied. Enzyme-linked immunosorbent assays (ELISA) were used for monitoring the atrazine and alachlor concentrations in 98 water samples taken from these areas. Seventy-nine of the samples were of ground waters and 19 were of surface waters. The concentration ranges of the herbicides detected in the study period (October 1997–October 1998) were 0.04–25.3 g L^–1 in the surface waters and 0.04–3.45 g L^–1 in the ground waters for atrazine, and 0.06–31.9 g L^–1 in the surface waters and 0.05–4.85 g L^–1 in the ground waters in the case of alachlor. The highly significant correlation observed between the concentrations of both herbicides in the surface waters (r = 0.89, p < 0.001) pointed to a parallel transport of atrazine and alachlor to these waters. A study was made of the temporal evolution of the concentrations of both herbicides, and it was found a maximum recharge of atrazine in the ground waters for April 1998 and of alachlor in October 1997 and October 1998. The temporal evolution of the concentrations of both herbicides in surface waters was parallel. The highly significant correlations observed between atrazine concentrations determined by ELISA and by HPLC (r = 0.92, p < 0.001) and between alachlor concentrations also determined by both methods (r = 0.96, p < 0.001) confirmed the usefulness of ELISA for monitoring both herbicides in an elevated number of samples. Using HPLC, the presence in some waters of the alachlor ethanesulfonate (ESA) metabolite was found at a concentration range of 0.52–4.01 g L^–1. However the interference of ESA in the determination of alachlor by ELISA was negligible. The inputs of atrazine and alachlor to waters found in this study, especially the inputs to ground waters, could pose a risk for human health considering that some waters, though sporadically, are even used for human consumption.     

Remediation of alachlor and atrazine contaminated water with zero-valent iron nanoparticles

Zero-valent iron nanoparticles (nZVI, diameter < 90 nm, specific surface area = 25 m² g^?1) have been used under anoxic conditions for the remediation of pesticides alachlor and atrazine in water. While alachlor (10, 20, 40 mg L^?1) was reduced by 92–96% within 72 h, no degradation of atrazine was observed. The alachlor degradation reaction was found to obey first-order kinetics very closely. The reaction rate (35.5 × 10^?3–43.0 × 10^?3 h^?1) increased with increasing alachlor concentration. The results are in conformity with other researchers who worked on these pesticides but mostly with micro ZVI and iron filings. This is for the first time that alachlor has been degraded under reductive environment using nZVI. The authors contend that nZVI may prove to be a simple method for on-site treatment of high concentration pesticide rinse water (100 mg L^?1) and for use in flooring materials in pesticide filling and storage stations.     

Adsorption of chloroacetanilide herbicides on soil and its components Ⅲ. Influence of clay acidity, humic acid coating and herbicide structure on acetanilide herbicide adsorption on homoionic clays

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite, soil humic acid, and their mixtures was studied by coupling batch equilibration and FT-IR analysis. Adsorption isotherms of acetochlor, alachlor, metolachlor and propachlor on Ca²⁺-, Mg²⁺ -. Al³⁺ -and Fe³⁺ -saturated clays were well described by the Freundlich equation. Regardless of the type of exchange cations, Kf decreased in the order of metolachlor ＞ acetolachlor ＞ alachlor ＞ propachlor on the same clay. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in binding, probably via H-bond with water molecules in the clay interlayer. The type and position of substitutions around the carbonyl group may have affected the electronegativity of oxygen, thus influencing the relative adsorption of these herbicides. For the same herbicide, adsorption on clay increased in the order of Mg²⁺ ＜ Ca²⁺ ＜ Al³⁺ ≤ Fe³⁺ which coincided with the iucreasing aciditv of homoionic clays. Acidity of cations may have affected the protonation of water, and thus the strength of H-bond between the clay water and herbicide. Complexation of clay and humic acid resulted in less adsorption than that expected from independent adsorption by the individual constituents. The effect varied with herbicides, but the greatest decrease in adsorption occurred at a 60:40 clay-to-humic acid ratio for all the herbicides. Causes for the decreased adsorption need to be characterized to better understand adsorption mechanisms and predict adsorption from soil compositions.     

催化臭氧化饮用水中甲草胺的研究

利用Fe2+、Mn2+和腐殖酸对水中甲草胺进行了催化臭氧化研究.实验表明,少量的催化剂就可促进甲草胺的降解,过量则会产生抑制作用.深入研究表明,甲草胺的降解与具有极强氧化能力的羟基自由基有关.     

甲草胺和丁草胺等除草剂在多介质环境中环境行为综述

本文详细综述了甲草胺和丁草胺的物理化学性质,总结了它们在土壤和水中的迁移,吸附和微生物降解转化,对动植物的毒性和作用机制,酰胺类除草剂在分析检测方面的进展以及在污染的防治与修复方面的一些措施     

Decontamination of alachlor herbicide wastewater by a continuous dosing mode ultrasound/Fe2+/H2O2 process

We used a ultrasound/Fe2+/H2O2 process in continuous dosing mode to degrade the alachlor.Experimental results indicated that lower pH levels enhanced the degradation and mineralization of alachlor. The maximum alachlor degradation(initial alachlor concentration of 50 mg/L) was as high as 100% at pH 3 with ultrasound of 100 Watts, 20 mg/L of Fe2+, 2 mg/min of H2O2 and 20℃ within60 min reaction combined with 46.8% total organic carbon removal. Higher reaction temperatures inhibited the degradation of alachlor. Adequate dosages of Fe2+and H2O2 in ultrasound/Fe2+/H2O2process not only enhance the degradation efficiency of alachlor but also save the operational cost than the sole ultrasound or Fenton process. A continuous dosing mode ultrasound/Fe2+/H2O2 process was proven as an effective method to degrade the alachlor.     

PESTICIDE ACCUMULATION IN A NEW IMPOUNDMENT IN IOWA1

ABSTRACT: Estimates were made of the amounts of selected pesticides entering and leaving Saylorville Reservoir, a new partly filled impoundment on the Des Moines River. Samples were collected at 1– or 2-week intervals at stations above, in, and below the reservoir. Atrazine, alachlor, and cyanazine were found only in the dissolved state, and dieldrin and p, p′ -DDE in both the, dissolved and suspended state. Heptachlor epoxide, p,p-DDT. p, p′ -DDD, 2,4-D, 2,4,5-TP, endrin, lindane, methoxychlor, propachlor, and toxaphene were not detected or were at very low concentrations. Estimated deposition in the reservoir from September 1977 to October 1978 was 281 kg atrazine, 251 kg alachlor, 26 kg cyanazine, 16 kg dieldrin, and 20 kg p, p′ -DDE.     

饮用水中内分泌干扰物甲草胺的O3氧化降解机制研究

研究了饮用水中一种具有内分泌干扰作用的有机污染物甲草胺的臭氧氧化降解机制.采用液相色谱、气相色谱、UV吸收及离子色谱对甲草胺臭氧氧化降解反应的中间产物和最终产物进行跟踪分析.结果表明,O₃在酸性条件下单独作用时,反应进行30 min后就可去除甲草胺约94%,但TOC仅去除了约35%, 这说明O₃氧化降解甲草胺的过程不能完全矿化为CO₂和H₂O.通过UV和液相色谱可观察到反应过程中大量中间产物的生成,其中有一定量的小分子有机酸产生,导致处理后水的pH从5.96下降到3.94,反应中无机离子的产生也证实了甲草胺的结构在一定程度上被破坏.     

Herbicide movement and dissipation at four midwestern sites

Abstract

This study was conducted to evaluate atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl‐1, 3, 5‐triazine) and alachlor (2‐chIoro‐N‐(methoxymethyl)acetamide) dissipation and movement to shallow aquifers across the Northern Sand Plains region of the United States. Sites were located at Minnesota on a Zimmerman fine sand, North Dakota on Hecla sandy loam, South Dakota on a Brandt silty clay loam, and Wisconsin on a Sparta sand. Herbicide concentrations were determined in soil samples taken to 90 cm four times during the growing season and water samples taken from the top one m of aquifer at least once every three months. Herbicides were detected to a depth of 30 cm in Sparta sand and 90 cm in all other soils. Some aquifer samples from each site contained atrazine with the highest concentration in the aquifer beneath the Sparta sand (1.28 μg L^‐1). Alachlor was detected only once in the aquifer at the SD site. The time to 50% atrazine dissipation (DT₅₀) in the top 15 cm of soil averaged about 21 d in Sparta and Zimmerman sands and more than 45 d for Brandt and Hecla soils. Atrazine DT₅₀ was correlated positively with % clay and organic carbon (OC), and negatively with % fine sand. Alachlor DT₅₀ ranged from 12 to 32 d for Zimmerman and Brandt soils, respectively, and was correlated negatively with % clay and OC and positively with % sand.     

甲草胺热裂解气相色谱-质谱分析

甲草胺是一种广泛用于农作物上的酰胺类除草剂.本文利用裂解气相色谱与质谱联用(Py-GC-MS)研究了甲草胺在热裂解温度200℃、400℃、600℃、800℃下的降解产物和热降解机理.实验结果表明,共有60种裂解产物被分离鉴定,随着温度的升高甲草胺显著分解,当裂解温度超过600℃时,大量的芳烃类、喹啉类、吲哚类化合物在高温裂解中产生,温度越高他们的相对含量也越高.基于对裂解产物的定性和它们含量的变化提出了甲草胺的热降解机理.