环境化学土壤有机农药部分英文翻译.docx

446 ORGANIC BIOCIDES 5. A carbamate hydrolyses to generate an amine, an alcohol, and carbon dioxide:The hydrolysis reaction for carbaryl，a very widely used horticultural insecticide, occurs as follows. In this case, the aromatic alcohol 1-naphthol is formed:6. The thiocarbamate family likewise reacts to form amines, thiols, and carbon dioxide:This is illustrated by the hydrolysis of benthiocarb, a selective pre-emergence herbicide used especially against annual grasses and broad leaf weeds in rice fields:Benthiocarb 7. A well known example of hydrolysis occurs with the triazine herbicides:An example is the hydrolysis of simazineSimazine hydroxysimazine OxidationOxidation reactions are extremely important in terms of the total degradation of organic species in the environment. For oxidation to occur, an appropriate oxidant must be avail-able; the nature of the oxidant depends on the environmental circumstance. In surface soils and water, where the pE: is high, there is a plentiful supply of oxygen and in addition,446 有机农药5一个氨基甲酸酯水解生成胺,酒精,和二氧化碳.: 胺甲萘的水解反应是一种被广泛使用的园艺杀虫剂,它的反应发生如下。在这种条件下反应生成了芳香醇-萘酚甲萘威6.硫代氨基甲酸酯族发生同样反应生成胺,硫醇,二氧化碳灭草丹的水解就举例证明了,这种选择性预防种子萌发的除草剂，尤其是在治理稻田里一年生禾本科牧草阔叶杂草上得到了广泛应用 杀草丹一个众所周知的水解例子伴随着三嗪除草剂出现另一个例子是西玛津的水解 西玛津 2-羟基-4,6-二（乙氨基）-1,3,5-三嗪化学氧化对于环境里的有机物种类的总降解，氧化反应是非常重要的。氧化反应的发生，必须有适当的氧化剂，氧化剂的性质取决于环境的情况。在表层的土壤和水，只要PE（电子活度）足够高就会有充足的氧气供应，此外CHEMICAL STABILITY 447more powerful oxidants produced by photochemical processes may be present. These include the hydroxyl radical, hydrogen peroxide, ozone, and singlet oxygen (0(D). While the concentration of each of these species is normally small compared with ground-state dioxygen (02(3Cg-).they can play a dominant role in bringing about oxidation of otherwise refractory molecules. Under the variety of anoxic conditions, other less powerful oxidants like nitrate and sulfate are potential electron acceptors for the oxidation of biocides. When all oxidants are depleted, reductive degradation becomes operative. Some of the types of oxidation reactions are as follows.1. Alkanes or aliphatic hydrocarbon substituents are oxidized, often at the terminal group, to produce alcohols, aldehydes, and then carboxylic acids:Various microorganisms using unique mechanisms are capable of bringing about parts or all of this sequence. Subterminal oxidation is also possible.2.Alkenes are oxidized through a number of processes resulting in the production of ketones, alcohols, and carboxylic-adds. When attack occurs at the double bond, the following reaction sequence occurs from alkene to epoxide to 1,2-diol tohydroxy acid and finally to a carboxylic acid that has one less carbon than the original alkene.3.Branched chain hydrocarbons, while somewhat more stable than straight chain molecules, undergo similar types of biological oxidation processes. Alicyclic hydrocarbons are highly resistant to oxidative degradation in most situations.4.Aromatic hydrocarbons are also highly resistant to oxidation reactions as was observed in our earlier discussion of polyaromatic hydrocarbons in the atmosphere. Nevertheless, oxidation does occur with the rate and extent strongly influenced by the nature of substituents on the molecule. Halogens, nitro-, and sulfonate groups are stabilizing compared with hydroxyl，methoxy, and carboxylate groups. The number and position of substituentsis also important.One mechanism for the oxidation of benzene itself involves the initial formation of an epoxide or oxirane which is subsequently converted to the diol with concomitant rearomatization of the benzene ring:化学稳定性447可能会出现因光化学过程而产生的更强的氧化剂。其中包括氢氧自由基、过氧化氢、臭氧、和单线态氧(O(D)。而与基态氧分子相比，每一个这些物种的浓度通常都比较小。(O2(3Cg-)他们可以发挥主导作用,带来其他耐火材料分子的氧化剂。在各种各样的缺氧条件下,其它不那么强的氧化剂，如硝酸和硫酸，是氧化杀虫剂的潜在的电子受体。当所有氧化剂枯竭,降解还原变得有效。一些类型的氧化反应如下。1.烷烃或取代基脂肪族烃氧化,通常在末端基,产生醇、接着是醛、最后是羧酸各种微生物使用独特的机制能够带来部分或所有这些序列。接近末端的氧化也是可能的2.烯烃通过一系列的氧化过程导致产生酮、醇、羧酸。当双键受到攻击时,下面的反应序列会依次按照烯烃、环氧化物、邻二醇、-羟基酸（果酸）、最后是比原始烯烃少一个碳的羧酸的顺序发生。 3.在接受类似的生物氧化过程中，支链碳氢化合物,而比直链分子更稳定，接受类似的生物氧化过程。在大多数情况下，脂环族碳氢化合物能够高度抗氧化降解。4. 在我们先前关于大气中的多环芳香烃的讨论中，就已经观察到了芳烃也能高度抗氧化反应。然而，氧化的确会在速率和程度被取代基分子性质的强烈影响下发生。与羟基、甲氧基、羧酸盐相比，卤素、硝基和磺酸盐会更稳定。取代基的数量和位置也很重要。一个苯的氧化机制本身涉及到环氧或环氧乙烷的初始构造，这是随后转化为伴随着苯环重新芳构化的二醇448 ORGANICFurther oxidation can lead to ring fission with the production of a dicarboxylic acid: The rate of oxidative degradation of petroleum residues is of considerable current interest with respect to leakage from gasoline tanks-and oil spills associated with extraction or transport of crude petroleum. Many of the generalizations regarding hydrocarbon decomposition have been found to apply in a study2 of the microbial degradation of petroleum drilling cuttings. The cuttings, containing fuel oil, calcium salts and a small amount of emulsifier had a pH of 9.1, an organic matter content of 12.4% and a carbon：nitrogen ratio of 103. They were applied to a silty clay agricultural soil, of pH 5.1, organic matter 2.62%, and carbon:nitrogen ratio of 8.4. If the soils had been sterilized, there was little or no degradation over a 9 month period, but in non-sterilized soils, about 75% of the original mass of hydrocarbon was degraded during this time. Amongst the classes of hydrocarbon, there were very large differences in decomposition rate, with essentially all the low molar mass alkanes (those with less than 27 carbons) being degraded within 16 days. There was slower decomposition of branched chain and aromatic fractions. The residual unreacted material was an unresolved .complex mixture of mostly high molar mass hydrocarbons.5. Particular functional groups of biocide molecules are also subject to oxidative processes, although biotic hydrolysis reactions more often initiate a degradative sequence. A thioether sulfur atom can be oxidized in two-steps; first to a sulfoxide and then to a sulfone (reaction 20.28): thioether sulfoxide sulfoneAldicarb is a potent and broad spectrum insecticide, acaricide (active against spiders) and nematicide (active against nematodes), which is susceptible to such oxidation (reaction 20.29). As in the case of parathion, the oxidized analogue is more toxic than the original compound: aldicarb6. Another very important oxidative reaction is oxidation of fatty acid side chains, through a ketone intermediate to an acid with two fewer carbons in the chain: 448 有机物进一步氧化会导致环裂变而产生二羧酸在关于原油提取和运输中，坦克汽油泄漏和石油泄漏方面，石油残留量的氧化降解速率是相当大的。许多归纳有关碳氢化合物分解被发现应用于一项石油钻井岩屑微生物降解的研究中。这种是包括岩屑,含燃油、钙盐以及少量pH值为9.1,有机质含量为12.4%，碳氮比为103的乳化剂。他们被应用于pH值为5.1,有机物含量为2.62%,碳氮比为8.4的粉质粘土农业土壤。如果土壤经过杀菌消毒,在九个月内有极少或根本没有降解反应,但在没有杀菌消毒的土壤中,在这期间内，大约有75%的碳氢化合物的原始质量会发生降解。碳氢化合物类,在分解率有很大差异,基本上所有的低摩尔质量烷烃(少于27个碳)16天内会被降解。支链和芳香馏分会比较慢地分解。剩余未反应的材料是一个尚未解决的主要由高摩尔质量的碳氢化合物组成的复杂混合物。5. 尽管生物水解反应经常发起一个趋向下降的序列，杀虫剂分子的特定官能团也会受到氧化过程。硫醚硫原子可以在两步被氧化;第一步被氧化成亚砜，然后是砜 (反应20.28) 硫醚 亚砜 砜涕灭威是一个有效的广泛性杀虫剂,杀螨剂(主动针对蜘蛛)和杀线虫剂(主动针对线虫),它们都容易受到这种氧化的影响 (反应20.29)。对于硫磷来说，氧化类似物比最初的化合物更具毒性。 涕灭威6.另一个非常重要的氧化反应。脂肪酸侧链的氧化,通过酮的中间物到在主链上有少两个碳原子的酸CHEMICAL STABILITY 449 An example of this reaction is conversion of MCPB (2-(4-chloro-2-methylphenoxy) butryic acid), a herbicide used for post-emergence weed control in cereals and pasture, to MCPA (4-chloro-2-methyl-phenoxyacetic acid), as shown: ReductionReduction reactions occur in low pE environmental situations such as anoxic groundwater and flooded soils. Some important and well defined biotic degradation processes take place in these situations.1. Dehalogenation is a principal process of degradation of refractory halogenated organic compounds. While oxidative decomposition of such compounds is slow, the reduction reactions are frequently faster in some waste water treatment processes, advantage is taken of the increased rate in order to enhance the degradation of halogenated compounds present in a waste stream. It is also a possible means by which halogenated compounds are detoxified in a sanitary landfill. Zero-valent iron may be used as a reductant to increase the rate of reaction. Two general dehalogenation have b