新农药硫肟醚在土壤中的降解

在实验室条件下对新农药硫肟醚[o-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]在不同地区土壤中的降解动态进行了研究.结果表明,硫肟醚在土壤中的降解遵循一级动力学方程.硫肟醚在非灭菌与灭菌长沙粉砂质黏土中的降解速率常数(k)分别为8.106×10^-3和1.630×10^-3,半衰期分别为85.5d和425.2d,微生物对硫肟醚在土壤中的降解具有显著的影响.硫肟醚在3种土壤中的降解速率大小依次为湖南永州重黏土>甘肃天水黏土>辽宁沈阳粉砂质黏土,其降解半衰期分别为46.1,63.8,70.0d,降解速率常数分别为1.503×10^-2,1.087×10^-2,9.904×10^-3.根据国内农药在土壤中的残留期划分标准,硫肟醚属于较易降解类农药.     

甲黄隆在有机溶剂中的光解

以中压汞灯为光源,研究了甲黄隆在甲醇和丙酮等有机溶剂中的光解动力学,结果表明均为一级反应。甲黄隆在甲醇中的光解速率与在水中相差不大,而丙酮可明显促进其光解。甲黄隆在甲醇中光解先断裂脲桥,生成磺酰胺和取代三嗪,磺酰胺继续光解生成苯甲酸甲酯和微量的硫酚。     

丁草胺在水体中的光解和稻田中归趋的研究

丁草胺在太阳光下，纯水中稳定，田水中消解较快。在模拟太阳的紫外光下，水体的ｐＨ值和溶解氧对其光解无影响；丙酮可加速其光解；Ｈ２Ｏ２可诱发化学氧化和水解，同时加速光解反应。主要光解产物被分离、鉴定。丁草胺在水中不易挥发，能够被土壤吸附。在田间丁草胺在水中消解较快，半衰期〈１ｄ，８－１６ｄ检不出；在土壤中，半衰期为３．３ｄ，３０ｄ后检不出。     

敌草快在水溶液中的光解动力学研究

常温常压条件下,用500 w高压汞灯和太阳光分别照射处理敌草快水溶液,考察光照和初始浓度对敌草快在水溶液中光降解的影响。研究表明,分别用500 w高压汞灯和太阳光照射下,敌草快的光解反应均符合一级动力学规律,降解半衰期分别为0.11 d和240.63 d;敌草快的初始浓度越大,其光解率越小,光解率与其初始浓度呈负相关。     

异丙草胺在水溶液中的光解动力学

常温条件下,用400W高压汞灯和太阳光分别照射处理异丙草胺水溶液,考察光照和初始浓度对异丙草胺在水溶液中光降解的影响研究表明,太阳光照射下,异丙草胺的光解反应符合一级动力学规律,降解速率相对很小,在石英试管中1h的光解率只有5.5%;汞灯照射条件下异丙草胺的光解过程可用双室降解模式来描述,1h时的光解率可达80.9%;异丙草胺的初始浓度越大,其光解率越小,降解产物的生成影响异丙草胺本身的光解进程.运用GC-MS技术鉴定出异丙草胺的主要光解产物有6种,光解过程中苯环保持完好,并推测了异丙草胺的光解反应机理.     

有机磷农药在土壤环境中的降解转化

有机磷农药是世界上应用最广泛的农药种类之一。有机磷农药是属于比较容易降解，而且对环境污染较小的一类农药，从有机磷农药的性质出发，着重讨论了有机磷农药的水解，光解和微生物降解等，在土壤中的主要降解转化过程。     

磺酰脲类除草剂在环境中的光降解研究——水溶液中的光解动力学

以汞灯为光源,研究了甲黄隆,苯黄隆,氯黄隆,氯嘧黄隆,苄嘧黄和胺苯黄隆６种磺酰脲类除草剂在水液中的光解动力淡。结果表明,５种磺酰的降解呈一级动力学反应;体系的ＰＨ值对降解速率影响不明显,光强的影响较明显著;Ｈ２Ｏ２丙酮和溶解有机质均可促进磺酰光解;党妥氧对该类除草剂光解的影响表现为光氧化与淬灭２种作用的竞争。     

新农药环境化学行为研究（V）─—三氟羧草醚（Acifluorfen）在土壤和水环境中的滞留、转化

从如下几方面研究了三氟羧草醚在土壤－水环境中的化学行为：一是土壤对该药的吸附，结果表明，吸附强度与土壤理化特性密切相关，Ｆｒｅｕｎｄｌｉｃｈ常数ｋ＿ｆ＝０．９４Ｗ＿（ＯＭ）＋０．６５Ｗ＿（ＣＬＡＹ）－９．５９ｐＨ（ｒ￣２＝０．９４）；二是吸附机理研究，发现三氟羧草醚能与碱金属以外的许多金属离子形成配合物，并证实了与Ｃｕ￣（２＋）形成的双核桥联配合物的可能性；三是实验指出它在水中避光有一定的稳定性，不易水解；四是它在＜３５０ｎｍ的光辐照下，易脱羧转化，速度较快，光解产物有较好的稳定性。     

多环芳烃蒽、屈在水体中的光解动力学模拟研究

研究了紫外光和太阳光下蒽、在甲醇一水溶液中的光分解反应结果表明,水中较低浓度葱、的光解表观上呈一级反应动力学规律,微观上是二级反应的加和蒽和的光解速率常数随着温度升高、光照距离减小及水中溶解氧增加而增大,但与水中急和宏的初始浓度无关黄浦江沉积物作为悬浮物加入后蒽和的光解效率下降对蒽和光解速率的比较分析表明,多环芳烃光解速率常数与受光解物质的结构特性有关     

小球藻对新杀虫剂HNPC-A9908的富集与降解

HNPC-A9908[O-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]是国家南方农药创制中心湖南基地研制成功的具有自主知识产权的一种新型杀虫剂.作者研究了蛋白核小球藻对HNPC-A9908的富集与降解.结果表明,蛋白核小球藻具有降解HNPC-A9908的能力,在20,100,400mg/L的浓度下,5d内HNPC-A9908的降解率分别为90.50%、66.02%和43.19%,日平均降解速率分别为3.60,13.20,34.55mg/L,其降解动力学方程可用二级反应动力学方程很好地拟合,拟合度达到83%以上.此外,蛋白核小球藻对HNPC-A9908也具有一定的富集能力,当浓度为20,100,400mg/L时达到最大富集的时间分别为24,48,48h,富集量分别为11.58,15.15,16.42mg/gFW,此后随时间的延长而逐步降低.     

Dynamics of novel insecticide HNPC-A9908 residue in vegetable-field ecosystem

HNPC-A9908 （o-（3-phenoxybenzyl）-2-methylthio-1-（4-chlorophenyl） propyl ketone oxime）, a novel oxime insecticide, is a highly effective and broad-spectrum insecticide which can be widely used to control many species of foliar insects on various crops. A study was conducted to evaluate the fate of HNPC-A9908 and study the degradation dynamics of HNPC-A9908 residue in vegetable field ecosystem. The results showed that degradation of HNPC-A9908 was much faster in vegetable pakchoi than in soil, and its half-life in pakchoi and soil was 1.32 and 3.75 d, respectively. The final residue of HNPC-A9908 in pakchoi was at the undetectable level to 0.122 mg/kg. As a conclusion, a dosage of 90 g/hm^2 was suggested and considered to be safe to human beings and animals.     

Photodegradation of new herbicide HW-02 in organic solvents

HW-02 is a new organophosphates herbicide which is discovered and developed in China. The kinetics and mechanism of HW- 02 photodegradation in the organic solvents were studied at 25°C under the irradiation of ultraviolet light. The results showed that photochemical reaction of HW-02 in organic solvents such as n-hexane, methanol, dimethyl benzene and acetone under UV light could be well described by the first kinetic equation, and the photodegradation efficiency decreased with a order of n-hexane methanol xylene acetone. The photodegradation efficiency constant of HW-02 in n-hexane, methanol, xylene and acetone were 4.951 × 10 2 , 3.253 × 10 2 , 2.377 × 10 2 and 1.628 × 10 2 min 1 , and the corresponding half-lives were 13.99, 21.20, 29.15 and 42.56 min, respectively. By separation and identification of photoproducts using GC-MS, it could be concluded that HW-02 was photolyzed through ester cleavage, photo-dechlorination and photoisomerization of the molecule itself.     

Abiotic degradation of four phthalic acid esters in aqueous phase under natural sunlight irradiation

Abiotic degradability of four phthalic acid esters (PAEs) in the aquatic phase was evaluated over a wide pH range 5–9. The PAE solutions in glass test tubes were placed either in the dark and under the natural sunlight irradiation for evaluating the degradation rate via hydrolysis or photolysis plus hydrolysis, respectively, at ambient temperature for 140 d from autumn to winter in Osaka, Japan. The e ciency of abiotic degradation of the PAEs with relatively short alkyl chains, such as butylbenzyl phthalate (BBP) and di-nbutyl phthalate (DBP), at neutral pH was significantly lower than that in the acidic or alkaline condition. Photolysis was considered to contribute mainly to the total abiotic degradation at all pH. Neither hydrolysis nor photolysis of di-ethylhexyl phthalate (DEHP) proceeded significantly at any pH, especially hydrolysis at neutral pH was negligible. On the other hand, the degradation rate of diisononyl phthalate (DINP) catalyzed mainly by photolysis was much higher than those of the other PAEs, and was almost completely removed during the experimental period at pH 5 and 9. As a whole, according to the half-life (t1=2) obtained in the experiments, the abiotic degradability of the PAEs was in the sequence: DINP (32–140 d) > DBP (50–360 d), BBP (58–480 d) > DEHP (390–1600 d) under sunlight irradiation (via photolysis plus hydrolysis). Although the abiotic degradation rates for BBP, DBP, and DEHP are much lower than the biodegradation rates reported, the photolysis rate for DINP is comparable to its biodegradation rate in the acidic or alkaline condition.     

Photolysis of polycyclic aromatic hydrocarbons on soil surfaces under UV irradiation

Photolysis of some polycyclic aromatic hydrocarbons (PAHs) on soil surfaces may play an important role in the fate of PAHs in the environment.Photolysis of PAHs on soil surfaces under UV irradiation was investigated.The effects of oxygen,irradiation intensity and soil moisture on the degradation of the three PAHs were observed.The results showed that oxygen,soil moisture and irradiation intensity enhanced the photolysis of the three PAHs on soil surfaces.The degradation of the three PAHs on soil surfaces is related to their absorption spectra and the oxidation-half-wave potential.The photolysis of PAHs on soil surfaces in the presence of oxygen followed pseudo first-order kinetics.The photolysis half-lives ranged from 37.87 days for benzo[a]pyrene to 58.73 days for phenanthrene.The results indicate that photolysis is a successful way to remediate PAHs-contaminated soils.     

节球藻毒素的紫外光降解研究

为优化节球藻毒素(NOD)光解处理的最佳光源及反应条件,利用自制光反应装置研究了NOD在暗反应、可见光、暗反应+TiO_2、可见光+TiO_2及单独紫外光(UVA、UVB、UVC)处理下的去除效果,继而选择UVC作为最佳光源进行后续实验,探讨NOD初始浓度、温度、p H和光强对NOD去除效果的影响及反应动力学.结果表明:暗反应、可见光、可见光+TiO_2的组合、UVA和UVB均对NOD无显著去除作用,最高去除率约为20%;UVC处理可以快速去除水中NOD,其去除过程符合二级动力学.UVC处理时,pH对NOD的去除无显著影响;温度升高,NOD去除率缓慢增大,但组间差异并不显著;初始浓度越大,NOD去除率越低;光强增大,NOD去除率快速升高,但到达一定临界值后保持稳定状态.3种因素对UVC去除NOD的影响程度由大到小分别为:光强时间温度.光强318μW·cm~(-2)、p H=7、温度30℃、反应时间4 h为最佳处理条件,此时NOD去除率最高,初始浓度为0.1μg·m L~(-1)的NOD几乎被完全去除,残留浓度低于WHO及我国规定的藻毒素含量限值.研究表明,UVC光解NOD安全高效,是一种非常理想的NOD去除方法.     

四环素在水体中的自然光解作用机制

近年来,抗生素引发的水体环境污染问题日益受到关注,光解是其在环境中消减的重要过程,但其中的关键机制及影响因素尚不明确.本研究系统地考察了初始浓度、pH以及无机离子、溶解性有机物等环境因子对四环素（TC）光解的影响,明确了自然光解的关键活性氧物种（ROS）,同时结合理论计算和降解产物的分析,揭示出了TC的自然光解路径及作用机制.结果表明,模拟自然光条件下TC可快速降解,5 μmol·L^-1 的TC在180 min内降解率为75.0%,符合一级反应动力学,反应速率常数为0.007 min^-1,远高于避光条件.随着TC初始浓度的上升,TC光解率和速率呈现出下降的趋势,并且碱性条件更有利于TC光解.水体中存在Cu（II）、Fe（III）和NO₃^-均能显著促进TC光解;富里酸（FA）则由于光屏蔽和淬灭作用对TC的光解产生显著抑制,但FA 和Fe（III）共存时,Fe（III）对光解的促进作用占主导.水体中TC的自然光解不仅存在直接光解,并且以超氧阴离子（O₂^-·）和羟基自由基（·OH）为关键ROS的自敏化光解在TC的光解过程中也起到重要作用.结合TC光解后的产物分析发现,发生间接光解后TC发生开环反应,相比于直接光解和自敏化光解降解地更充分.综上,TC在自然水体中的光解强烈受环境因素影响,可以通过增强活性氧介导的间接光解过程促进水体抗生素污染修复.     

Photolysis kinetics and influencing factors of bisphenol S in aqueous solutions

The photodegradation of bisphenol S (BPS) in aqueous solutions was studied under different conditions. Photolysis and kinetics were investigated, as were the photolysis mechanism and the influences of initial pH value, light source, and environmental substances in water. The results showed that the photolysis of BPS occurred under UV light, and the rate increased with light source intensity. The photolysis of 5.0-50.0 mg/L BPS in water followed first-order kinetics: the rate was γ= 0.0161C_BPS under a 40-W UV-lamp, and the degradation half-life was 43.1 min. Due to its absorption of light, direct photolysis of BPS was a predominant pathway for BPS but was not obviously affected by reactive oxygen species. The results confirmed that the photolysis rates of BPS in alkaline water solution were faster than those in acidic and neutral water solution because of the ionization of BPS. The photodegradation rate of BPS increased in the presence of chloride and ferric ions, while the rate was inhibited by nitrate and phosphate in aqueous solution.