化学农药对生态环境安全评价研究 Ⅷ、农药在水体中和土壤表面的光降解

本文研究了呋喃丹、甲基对硫磷和γ—6663种不同类型的农药在水体中和土壤表面的光降解作用。试验表明,3种农药在水体中与土壤表面的光解速率为呋喃丹>甲基对硫磷>γ—666。试验同时表明,同一农药在不同土壤表面的光解速率基本相同,但不同农药在同一种土壤表面的光解速率则相差很大。该研究方法在新农药开发中可为评价农药的光稳性提供参考。     

表面活性剂和金属离子对新农药硫肟醚光解的影响

硫肟醚[O-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]是我国研制成功的具有自主知识产权的一种新型杀虫剂.在室内紫外光(λ254 nm)照射下研究了几种表面活性剂和金属离子对硫肟醚在水溶液中光解的影响.试验结果表明,当土温80(Tween80)、十二烷基苯磺酸钙(ABS-Ca)、蓖麻油聚氧乙烯醚(BY)、三氯化铁(FeCl_3)、硫酸铜(CuSO_4)和无水硫酸镁(MgSO_4)分别与硫肟醚以1:1的比例混合后,硫肟醚的光解速率发生了不同程度的改变.ABS-Ca对硫肟醚在水溶液中的光解速率表现出显著的光猝灭降解效应,蓖麻油聚氧乙烯醚类表面活性剂BY对硫肟醚在水溶液中的降解表现出一定程度的光敏化作用.而吐温80对硫肟醚在水体中光解速率的影响则随照光时间而改变,当照光时间小于40 min时,表现为光敏化降解作用,大于40 min时可延缓硫肟醚的光解进程,表现出光猝灭作用.Fe~(3+)使硫肟醚在水溶液中的光解速率增快,表现出明显的光敏化降解效应,而Cu~(2+)和Mg~(2+)使硫肟醚在水体中的光解速率减慢,表现为较强的光猝灭降解作用.硫肟醚在含Tween80、ABS-Ca、BY、FeCl_3、CuSO_4和MgSO_4水溶液中的光解半衰期分别为21.63、34.42、15.29、9.85、43.95和32.20 min,而在不含任何农药化肥的纯净水中的光解半衰期为22.30 min.     

三种丙烯菊酯系列产品的光解和水解稳定性

研究了富右旋反式丙烯菊酯、Es-生物丙烯菊酯、右旋丙烯菊酯 3种丙烯菊酯系列农药在水体中的光解以及不同温度、pH条件水体中的水解作用。结果表明 ,在 5 0 0W氙灯下 ,3种菊酯类农药在水溶液中的光解均呈一级动力学反应 ,3种农药的光解半衰期分别为 1.84 ,1.37和 1.5 1h ;在 2 5℃的酸性水溶液中 ,3种农药的水解速率很慢 ,半衰期均大于 16 2d ;水温的升高与碱性的增强均能加速水解过程。在 5 0℃的碱性水溶液中 ,3种农药的光解半衰期分别为 0 .2 1,0 .2 2和 0 .18d。虽然 3种丙烯菊酯异构体含量不同 ,但其光解、水解特性没有显著差别。本文对有关水解机理也作了初步分析。     

农药杀虫双的光解和挥发研究

本文研究了农药杀虫双及其降解产物沙蚕毒的光解和挥发,结果表明:杀虫双在水溶液中、沙蚕毒在甲醇溶液中的光解为一级动力学过程。在450W中压汞灯下的光解速率常数分别为0.33min~(-1)和0.15min~(-1),半衰期分别为2.10min和4.70min。在阳光下的光解速率常数分别为0.00308min~(-1)和0.033min~(-1),半衰期分别为3.75h和21.0min。它们在365nm波长下的光解量子产率分别为255.9相36.6。经初步测定,杀虫双、沙蚕毒在25℃时的饱和蒸气压分别为2.6×10~(-6)mm Hg和4.6×10~(-5)mm Hg。     

3种表面活性剂对有机氯农药污染场地土壤的增效洗脱修复效应

以有机氯农药生产企业工业场地污染土壤为对象,研究Tween80、TritonX-100和SDS这3种表面活性剂对土壤中氯丹(α-氯丹和γ-氯丹)、灭蚁灵、七氯、硫丹(α-硫丹和β-硫丹)的增溶洗脱效应.结果表明,3种表面活性剂对土壤中的有机氯农药均具有一定的增效洗脱作用,且洗脱去除率随表面活性剂添加量升高而逐渐增加.3种表面活性剂对土壤中氯丹、硫丹和七氯的去除率明显高于灭蚁灵,TritonX-100对灭蚁灵的去除率明显高于SDS和Tween80.Tween80和TritonX-100添加量为10g·L-1、SDS添加量为8.50g·L-1时,对土壤中4类有机氯农药的总去除率最高,分别为32.8％、59.7％和60.1％.对于该类污染场地土壤,选择10g·L-1 TritonX-100溶液在50℃条件下振荡5min时洗脱效果最好.     

冰晶中双氧水的UV光解

本文采用253.7 nm的紫外灯光解冰晶中的双氧水,研究其光解率随光照时间和温度的变化.以及Cl~-,SO_4~(2-)和CO_3~(2-)对其降解的影响,结果表明,相同条件下三种离子对其影响大小依次为:Cl~->SO_4~(2-)>CO_3~(2-).对比冰晶和水溶液中双氧水的光解,冰晶中双氧水的光解速率低于水溶液中双氧水的光解速率.紫外-可见光谱(UV-vis)分析其光解产物,没有发现新的物质生成.由此可以认为,冰晶中双氧水主要在冰晶笼子中进行反应,少部分在类似液体层(QLL)中降解.     

三种丙烯菊酯系列产品的光解和水解稳定性

研究了富右旋反式丙烯菊菌、Es-生物丙烯菊菌、右旋丙烯菊菌3种丙烯菊菌系列农药在水体中的光解以及不同温度1pH条件水体中的水解作用。结果表明，在500w氙灯下，3种菊菌类农药在水溶液中的光解均呈一级动力学反应，3种农药的光解半衰期分别为1．以，1．37和1．51h；在25℃的酸性水溶液中，3种农药的水解速率很慢，半衰期均大于162d；水温的升高与碱性的增强均能加速水解过程。在50℃的碱性水溶液中，3种农药的光解半衰期分别为0．21，0．22和0．18d。虽然3种丙烯菊酯异构体含量不同，但其光解、水解特性没有显著差别。本文对有关水解机理也作了初步分析。     

土壤表面农药光化学降解研究进展

农药在土壤表面的光化学降解是重要的非生物转化途径,其过程和产物对农药药效、代谢、毒性及环境影响重大.本文综述了土壤表面农药光解研究方法和影响农药光解的土壤因素,分析了农药在土壤表面的主要光反应类型,并讨论了土壤表面农药光解实际应用等方面的热点问题.     

双氯芬酸在水环境中光降解的初步研究

考察了在模拟太阳光照射下,双氯芬酸初始浓度、pH值、光强、温度、丙酮和双氧水对双氯芬酸光解的影响,并通过淬灭实验初步探讨了双氯芬酸光解.结果表明,双氯芬酸的光降解过程符合准一级动力学方程.光解速率随着双氯芬酸初始浓度的降低、光强的增强以及温度的升高而增大.当pH值从3变化到5时,反应速率常数变大;pH值从5变到8时,反应速率常数变小,再继续增大pH值,反应速率常数增大.水环境中存在的双氧水和丙酮对双氯芬酸的光解具有促进作用.最后,通过淬灭实验表明双氯芬酸的光解过程包括直接光解以及通过活性氧物种进行的自敏化光解.     

六六六(α-HCH)在水、冰和雪中的光化学反应

研究了紫外光作用下六六六(α-HCH)在水、冰和雪3种介质中的光化学反应,考察了α-HCH的光化学反应动力学、产物和机理.结果表明,在水、冰和雪中,α-HCH均可以发生光化学反应,且反应均符合一级动力学方程.光化学反应速率大小顺序为雪>水>冰.在水和冰中,α-HCH均生成了异构化产物β-HCH和γ-HCH,异构化机理是α-HCH分子中的氯原子改变原来的构像;由于雪中α-HCH的光化学反应较快,因此在雪中未检测到异构化产物.在3种介质中,α-HCH的光解产物均为二氯苯和五氯环己烯,其机理为氯化氢或氯原子的脱除反应.     

多环芳烃光解活性的量子化学研究

应用量子化学从头算HF／6-311 G(d)和B3LYP／6-311 G(d)方法计算了16种PAHs的多种量子化学参数,选取六种参数为分子结构的描述符,采用最小二乘法对16种PAHs的光解半衰期进行逐步多元线性回归分析,得到两个PAHs光解半衰期的QSAR模型,模型具有较高的相关系数,可有效地用于预测PAHs的光解半衰期,结果表明,HF方法所得模型优于B3LYP方法所得的模型,所得模型与基于半经验PM3算法的QSAR模型相比较,HF从头算方法所建立的QSAR模型比半经验PM3算法的结果要好,在所考查的诸多参数中,分子最高占有轨道特征值EHOMO对PAHs光解半衰期起着决定作用,最后,运用所得模型预测了3种PAHs的光解半衰期。     

Photodegradation of fungicide triadimefon and pesticide pirimicarb in aqueous TIO2 suspension

Two agrochemicals composed of nitrogen‐containing heterocyclic ring, triadimefon and pirimicarb, were degraded photocatalytically. The disappearance and TOC elimination rates of triadimefon were close to those of pirimicarb, whereas the photolysis of triadimefon was 4 times slower than that of pirimicarb. For triadimefon its aromatic moiety degraded quickly and Cl^‐ was released immediately, while triazole moiety degraded slowly. The formation rates of NH⁺ ₄ and NO₃ ^‐ by the degradation of triazole moiety were influenced by the rest of the molecule. The difference between disappearance and TOC elimination rates of both triadimefon and pirimicarb were far larger than those of aromatic compounds.     

Photodegradation of the organophosphorus insecticide ‘Phorate’

The photolysis of Phorate(I) (0,0‐diethyl S‐ethyl thiomethyl phosphordithioate) has been studied as a thin film on a glass surface and in a solution of methanol‐water (60:40) by ultraviolet light (λ > 290 nm). The rate of disappearance of Phorate in the solution show first order Kinetics with a rate constant of 4.9 × 10^–5 S ^–1. The half‐life of (I) exposed on a glass surface is found to be 5 hours. The structure of the major photoproducts were characterised by ¹H NMR and mass spectroscopy.     

冰相中双氧水体系罗丹明B的光解机理

研究了模拟太阳光作用下冰相中双氧水体系罗丹明B(RhB)光转化规律,考察了光照时间、温度、RhB初始浓度、pH值和双氧水剂量对RhB光解的影响.对照冰相与水相中RhB在双氧水体系中的光解效果,发现冰相中RhB的去除率远远低于水相,说明冰相中晶格的笼子效应限制了RhB与H2O2之间的反应.同时,研究了外加3种无机阴离子(还原性Cl-、氧化性SO42-和S2O82-)对冰相中RhB降解的影响,结果表明,3种离子都能促进冰相中双氧水体系RhB的光解,其中S2O82-能显著提高RhB的去除率.S2O82-和Cl-加入剂量越高,RhB去除率越高,而SO42-加入剂量增加会阻碍RhB的光解.依据研究结果,推测了冰相中RhB在双氧水体系中的光解历程与机理,为深入了解冰相中污染物自由基降解规律提供依据.     

Acute nitrate poisoning in two cattle

Abstract

The rate and product composition during photooxidation of aromatic hydrocarbons (toluene, o‐, m‐, p‐xylene and cumene) dissolved in n‐hexane and spread as a liquid film on water is reported. The photo degradability of these chemicals is 10–20%. The products identified are oxygenated aromatic compounds. It is observed that the absorption bands of the compounds under investigation depend upon the partial pressure of dissolved oxygen and these bands extend up to 290 nm. The new absorption band around 290 nm is probably due to broadening of ¹L_b bands which is responsible for direct photolysis.

stream. We have been especially interested in investigating the rate of disappearance and distribution of main oxidation products in two phases. Besides that an attempt has been made to throw some light on the reaction mechanism.     

7种农药对管氏肿腿蜂的毒性及初级风险评价

为评估农药对寄生类自然天敌昆虫的安全性,选择管氏肿腿蜂(Scleroderma guani Xiao et Wu)作为受试生物,采用管测药膜法测定了3种杀虫剂、2种除草剂、2种杀菌剂对其致死效应,并根据田间推荐剂量计算暴露量,采用风险商值HQ对杀虫剂进行风险评估。结果显示,与空白对照比较,3种杀虫剂均具明显毒性作用,其中丁硫克百威、吡虫啉和呋虫胺对管氏肿腿蜂的24 h半致死量(24 h-LR50)分别为5.11、2.92和0.06 g a.i.·ha-1,农田内风险商值分别为60.23、16.64和3 105。除草剂和杀菌剂在3倍最大田间推荐剂量作用下,24 h管氏肿腿蜂死亡率均小于50%。上述结果表明,在田间推荐用量下,3种杀虫剂对管氏肿腿蜂的初级风险评价为存在高风险,建议进一步开展高级阶段风险评估或者采取合理的风险管理措施来降低风险;除草剂和杀菌剂对管氏肿腿蜂的风险可接受。     

吡虫啉的光解水解和土壤降

在实验室测定了吡虫啉的光解、不同ｐＨ条件下的水解与在东北黑土等３种不同土壤中的降解。试验结果表明，在３００Ｗ低压汞灯下，吡虫啉水相溶液的光解呈一级反应动力学反应，光解半衰期为６．８１ｈ；在ｐＨ５、ｐＨ７、ｐＨ９的缓冲溶液中的水解半衰期分别为３０．６、１３．６与８．０ｄ；在东北黑土、太湖水稻土和江西红壤中的降解半衰期分别为１０．７、１１．１和４．１ｄ。     

Relationships between exposure to polyhalogenated aromatic hydrocarbons and organochlorine pesticides and the risk for developing type 2 diabetes: a systematic review and a meta-analysis of exposures to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)

A systematic review was performed to evaluate the association between environmental exposures to polyhalogenated aromatic hydrocarbons (PHAHs) and organochlorine (OC) pesticides and the risk for type 2 diabetes (T2D). Searches of EMbase, Google Scholar, Medline, and Scopus were performed. Reports were included if they were original human studies whose design included a control group and if the sample size was larger than 10 participants per group. The articles were excluded if the type of diabetes was unknown or Type 1. Odds ratios (OR), 95% confidence intervals (CI), and modified Naranjo scores for the effects of environmental contaminants were determined for each study. Of the 35 eligible studies, six were included in the meta-analysis; these focused specifically on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Meta-analysis of these studies showed no significant increased OR for the development of T2D from exposure to TCDD. However, subgroup analysis showed significant elevated OR for the development of T2D if exposure is repeated and accompanied by exposure to other persistent pesticides (OR?=?1.48; 1.10–1.90) but a decreased odds for T2D with exposure resulting from accidental exposure (OR?=?0.46; 0.39–0.52). Our results suggest that there are significant risks of developing T2D in populations with recurring exposures to TCDD in concert with other persistent chlorinated pesticides. A mean Naranjo score of 2.0 was determined for all 35 articles; this score was 2.5 when examining only TCDD studies and 2.1 when examining studies that looked only at T2D. Each of these Naranjo scores suggests a possible association between the prevalence of T2D and exposure to PHAHs or OC pesticides.     

The link between social network density and rank-order consistency of aggressiveness in juvenile eels

The emergence of an animal’s personality is the result of interactions between genetics, environment and experience. It is known that individuals are able to modulate their behaviour according to the context or the social environment. Many studies have shown for example, that familiarity among conspecifics diminishes aggressiveness, although little is known about the underlying processes. Nevertheless, personality traits have long been determined while ignoring the social context, especially in lower vertebrates such as fish. In the present experiment, we hypothesize that group connections (network density) may be positively correlated to consistency of aggressiveness by avoiding over-aggressive acts in further encounters. To test this hypothesis, we used eels (Anguilla anguilla) as a model species and monitored both aggressiveness and sociability in 64 individuals over their first 7 months of growth from the glass eel stage. As expected, social fish were less aggressive than their non-social counterparts at all times, highlighting the existence of a behavioural syndrome in eels. Additionally, rank-order consistency of aggressiveness was higher in groups of fish with high social connectivity, compared to those in less-connected fish groups. While aggressiveness must be consistent to be considered a personality trait, our results suggest that both aggressiveness and its consistency are influenced by initial social context.     

Modified ��-cyclodextrins as prospective agents for improving water solubility of organic pesticides

The drawback of some organic pesticides is their low water solubility. Cyclodextrins are used as agents for improving pesticides water solubility. However, the stabilization of the crystalline lattice can reduces to a large extent the solubility of cyclodextrins, especially β-cyclodextrin. Here, searching for the water soluble β-cyclodextrin derivatives, a set of new “host” compounds were prepared by the reaction of β-cyclodextrin with methyl epoxycinnamate. The reactants ratio was varied in to study the substitution degree of the obtained derivatives. The structure was determined by the ¹H-NMR and FT IR spectra. The average degree of substitution was determined by integration of the corresponding NMR signals and by elemental analysis. The solubility of four selected pesticides: dimethoate, simazine, linuron and thiram, in water with and without addition of the new modified β-cyclodextrin was measured by ultraviolet spectrophotometry. Our results showed that the modified β-cyclodextrins significantly improve solubility of pesticides.