Bioavailability of bound residue derived from ^(14)C-labeled chlorsulfuron in soil and its mechanism of phytotoxicity

The bioavailability of bound residue(BR) derived from 14 C-labeled chlorsulfuron in soil and effect of the main components of the BR on growth of rape(brassica napus) and rice(Oryza sativa L.) were investigated. The results showed that the BR with the concentration of 0 28 and 0 56 nmol/g air-dried soil, which was calculated by special radioactivity of 14 C-labeled chlorsulfuron parent compound, resulted in significant depression effect on growth of rape seedling. It was assured that the main components(2-amino-4-methoxyl-6-methyl-1,3,5-triazine, 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine, and 2-chloro-benzenesul-f onamide) of the BR did not inhibit the growth of rape and rice. LC-MS analysis demonstrated that the parent compound previously bound to the soil matrix could be again released and transformed into methanol-extractable residue during the course of rape growth. It was concluded that the molecular leading to the phytotoxicity to rape and rice in the BR is still the parent compound.

Identification of the bound residue composition derived from ^(14)C-labeled chlorsulfuron in soil by using LC-MS and isotope tracing method

A new method for extracting the bound residue(BR) derived from 14 C-labeled chlorsulfuron in soils was developed, and the technique of combining LC-MS with isotope tracing method was subsequently applied to identify the composition of the 14 C-BR in a loamy Fluvent derived from marine deposit. The results showed that the 14 C-[2-amino-4-methoxyl-6-methyl-1,3,5]-triazine, 14 C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine and 14 C-chlorsulfuron parent compound constituted the main composition of the 14 C-BR derived from 14 C-labeled chlorsulfuron in the soil. The radioactive ratio of three compounds accounted for 39.8%, 35.4% and 17.9% of total recovered radioactivity, respectively. However, a small amount(3.6% of total recovered radioactivity) of the complex of 14 C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine might have existed in the 14 C-BR in association with an unknown soil substrate. 2-chlorobenzenesulfonamide was also detected to be one of the components of the BR. The results could well explain the mechanism of phytotoxicity caused by the BR derived from chlorsulfuron in soil. In addition, the mechanism of BR formation in soil was also discussed in details.

Influence of chlorsulfuron herbicide on size of microbial biomass in the soil

A laboratory incubation experiment was conducted to study the effect of chlorsulfuron herbicide on the size of the microbial in loamy sand soil. The herbicide was applied, at four levels that were control, field rate 0\^01 (FR), 0\^1 (10FR) and 1 (100FR) μg/g. Determinations of microbial biomass C content and microbial biomass N content were carried out 1, 3, 5, 7, 10, 15, 25 and 45 days after herbicide application. In comparison to untreated soil, the microbial biomass carbon and biomass nitrogen decreased significantly in soil treated with herbicide in levels 10FR and 100FR within the first 10 days incubation. A more considerable increase in the microbial biomass C∶N ratio was observed in the herbicide treated soil than the non treated control. This effect was transitory and only at the higher rates of chlorsulfuron was significant.

Distribution of ^(14)C-chlorsulfuron bound residues in soil organic matter

The reason why chlorsulfuron(2-chloro-N-[4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide)bound residues can still make an in-jury to rotational crops is still kept unknown. The experiment was conducted under laboratory conditions to determine the dynamics of extractable and non-extractable (bound) residues of chlorsulfuron in soil, and the distribution of chlorsulfuron bound residues in organic matter fractions. The results showed that extractable 14C-residues decreased t0 25.12% of applied chlorsulfuron over an incubation period of 150 days;this in turn, the formation of bound residues increased to 47.07% of the applied. The proportions of 14C-bound residues in soil organic matter fractions increase in order of: humic acid (HA)<humin<fulvic acid(FA), most of bound residues ekisted in FA fraction, however, the amount of bound residues in humin fraction increase with incubation time. The fact that most of bound residues existed in water-soluble FA fraction is tentatively regarded as one of major reasons why 14C-chlorsulfuron bound residues can still make an injury to rotational crops.

Dynamic response of chlorsulfuron herbicide to nitrogen mineralization and the ratio of microbial biomass nitrogen to nitrogen mineralization in the soil

A laboratory incubation experiment was conducted to elucidate the effect of chlorsulfuron herbicide on nitrogen mineralization and the ratio of microbial biomass nitrogen to nitrogen mineralization (N mic /N min ratio) in loamy sand soil.The herbicide was applied at four levels that were control, field rate 0\^01 (FR), 10 times of field rate 0\^1(10FR),and 100 times of field rate 1\^0 (100FR) μg/g soil. Determinations of N\|mineralization and microbial biomass\|N content were carried out 1,3,5,7,10,15,25 and 45 days after herbicide application. In comparison to untreated soil, the N\|mineralization decreased significantly in soil treated with herbicide at levels 10FR and 100FR within the first 5 days incubation. A more considerable reduction in the N mic /N min ratio was observed in the herbicide treated soil than the non\|treated control.Among the different treatment of chlorsulfuron, 100FR displayed the greatest biocidal effect followed by 10FR and FR,showing their relative toxicity in the order of 100FR>100FR>FR.The results indicated that the side effect of this herbicide on N\|mineralization is probably of little ecological significance.

Evaluation on the Joint Action Between Chlorsulfuron and Haloxyfop-R by Bioassay

The joint action between chlorsulfuron and haloxyfop R was evaluated by bioassay with wheat and corn,respectivly.The dose response curve derived from wheat bioassay showed that the inhibition of haloxyfop R to wheat root growth wasn't affected by the increasing rate of chlorsulfuron.It indicated that chlorsulfuron had no antagonism to haloxyfop R.Meanwhile,the variation analysis of corn bioassay indicated that these two herbicides had joint action on inhibition to corn primary root growth.The joint action was evaluated as additive action by using Isobole Method.So chlorsulfuron and haloxyfop R could be used as tank mixture.

The release of ^(14)C-chlorsulfuron bound residue by autoclaving method and its identification

When individual microorganisms were used to release bound pesticide residues, it was ussually not take into full account whether the autoclavingmethod could lead to the release of bound residues. The soil containing bound 14Cchlorsulfuron residues was treated with an autoclave in this study. The results revealthat the bound 14C-chlorsulfuron residue can be released from the soil when treatedwith the autoclave and the release rate can be remarkably enhanced by adding water into the soil when subjected to such treatment. A TLC analysis showed that thereleased 14C-residue was one of the degraded products of 14C-chlorsulfuron. Afterderivatization and analysis using the GC-MS, the released 14C-residue was tentativelyidentified aS 2-amino-4-hydroXyl-6-methyl-1,3,

Electrochemical Degradation of Chlorsulfuron Herbicide from Water Solution Using Ti/IrO₂-Pt Anode

Chlorsulfuron (ChS) which is a nonbiodegradable herbicide was effectively removed using an electrochemical method at the Ti/IrO2-Pt anode. The influences of current density, initial ChS concentration, initial solution pH and different NaCl dosages on electrochemical degradation of ChS were investigated. HOCl formed during electrolysis and quickly generated .OH radicals would likely play an important role in the electrochemical degradation of ChS with the presence of NaCl. At current density of 20 mA?cm–2, ChS concentration decreased from 1 mg.L–1 to 0 mg.L–1 after 10 min electrolysis with 0.2 g?L–1 NaCl dosage. It was found that the ChS removal rate increased with increasing current density and the ChS degradation was similar at different initial pH values, which means that Ti/IrO2-Pt anode can be used in a wide pH range. The electrochemical performance of Ti/IrO2-Pt anode for degradation of ChS will not decrease after serviced for a long time. These results reveal that an electrochemical approach would be a novel treatment method for effective and rapid degradation of ChS herbicide from aqueous solution.

Determination of Herbicide Chlorsulfuron Residual Kinbetic and Accumulated Residues in Soil by Gas Chromatography

In this paper, residual kinetic and accumulated residues of chlorsulfuron in soil was studied by Gas chromatograhy. The result identify, chlorsulfuron was applied to winter wheat at rates of 15 g aiha -1 ; 30 g ai·ha -1 , degradation on of Half-life in soil were 43.2 days; 36.9 days, respectively, and one year later, the residues in soil were 0.34 ng·g -1 ; 0.43 ng·g -1 , respectively. Chlorsulfuron was applied continuously several years, the residues in soil was accumulated.

氯磺隆和苯磺隆对玉米乙酰乳酸合成酶抑制作用的研究

用玉米沙培主根长度法测定了玉米品种农大 3138和农大 10 8对氯磺隆和苯磺隆的相对敏感性。结果表明 ,农大 3138耐药能力比农大 10 8强 ,氯磺隆对玉米生长的影响比苯磺隆大。有关玉米离体乙酰乳酸合成酶(ALS)的研究结果表明 ,氯磺隆和苯磺隆对两种玉米离体ALS酶具有强烈的抑制作用 ,是玉米ALS酶的非竞争性抑制剂 ,氯磺隆对两种玉米ALS酶的抑制作用强于苯磺隆。低浓度的氯磺隆和苯磺隆对活体ALS酶无抑制作用 ,高浓度下才抑制活体ALS酶的活性。

麦谷宁生测方法及其对玉米的安全性研究

选用种植面积较大且抗逆性较强的玉米品种农大 10 8为指示植物 ,研究了麦谷宁的玉米沙培试验方法。结果表明 ,浸种催芽 ,播种后先盖覆沙量的一半后加药 6 0 m L,再盖沙至 2 cm厚 ,于 2 5℃黑暗培养 3d,可获得满意的结果。回归分析表明 ,麦谷宁浓度的对数与玉米主根长抑制率相对应的机率值成很好的线性关系 ,r2 均大于 0 .90。就大面积种植的 16个玉米品种对麦谷宁的敏感性测定结果表明 ,掖单 12对麦谷宁较敏感 ,农大 3138对麦谷宁耐药力最强 ,各品种对麦谷宁的 IC50 值均大于 7.38μg· kg-1。

农作物对磺酰脲类除草剂耐性的研究

不同作物品种对磺酰脲类除草剂的耐性有一定差异。春小麦不同品种对绿磺隆的耐性差异很小，但在不同温度条件下有一定差异。大豆品种问对立磺隆耐性不同，荆山朴、东农７７－８０４，哈３７－６４３７和７９０２的耐性最强，绿秣食豆、东农３９和龙６８０４耐性中等，合丰２５，礼炮２１６和东农３３耐性较差。玉米不同类型对玉农乐耐性不同，其耐性顺序为硬粒型＞一般型＞普甜型＞爆裂型。

一株绿磺隆降解菌的分离鉴定及其特性研究

从长期施用绿磺隆的土壤中采取土样 ,经驯化富集后筛选到一株能高效降解绿磺隆的细菌LHL 1菌株 ,经初步鉴定为黄单胞菌 (Xanthomonassp)。在此基础上 ,研究了该菌株对绿磺隆的降解特性。结果表明 :在绿磺隆浓度为 2 0mgL- 1的无机盐培养基中 ,3 0℃、1 5 0rmin- 1振摇 40h ,其对绿磺隆的降解率达 62 %。在所试的金属离子中 ,Pb2 +、Ag+抑制其生长 ,Ba2 +、Al3+、Zn2

绿黄隆在三种土壤中的降解

在实验室内，采用改进的玉米根长生测方法，定期测定一定温、湿度条件下绿黄隆在３种土壤中的残留动态。对降解时间和残留剂量进行回归分析，符合一级反应动力学指数方程Ｃ＝Ｃ０ｅ－ｋｔ，相关系数达极显著水平，半衰期ｔ１／２＝ｌｎ２／ｋ。实验结果表明，在２５℃、２５％温、湿度条件下，绿黄隆在太湖水稻土中降解最快，半衰期为１．６周；其次是砂姜黑土，半衰期为２．５周；高砂土中降解最慢，半衰期为１３．３周。分析认为，土壤ｐＨ值和微生物量是影响绿黄隆降解的主要因素。高温灭菌土壤测得绿黄隆在砂姜黑土的灭菌土和未灭菌土中，半衰期分别为２６．５周和２．１周；太湖水稻土的灭菌和未灭菌土中，半衰期分别为５．０周和０．９周。从而进一步证实，绿黄隆在太湖水稻土中以非酶水解和微生物活动共同降解，在碱性砂姜黑土中主要以微生物降解。探讨了绿黄隆在３种土壤中的残留动态对农业生产的重要性，建议长江流域碱性沙质土壤农区慎用或禁用绿黄隆。

氯磺隆的化学行为

氯磺隆是典型的乙酰乳酸合成酶抑制剂 ,在酸性条件下主要以中性分子形式存在 ,其水解反应是准一级的SN2 反应 ;在中性或碱性条件下 ,主要以阴离子形式存在 ,水解反应较慢 .在土壤中 ,除化学降解外 ,微生物降解也是氯磺隆另一重要环境归趋 ,而光化学降解并非氯磺隆环境归趋的主要方式 .

安全剂R-28725保护玉米免受氯磺隆药害的作用

采用生物测定法研究了安全剂R-28725保护玉米免受除草剂氯磺隆药害的作用。在氯磺隆毒土浓度为2μg/kg时,使用5mg/kg R-28725浸种处理,玉米根部受到氯磺隆抑制的谷胱甘肽(GSH)含量由空白对照的57.3%恢复至83.4%;玉米叶片中乙酰乳酸合成酶(ALS)活性增加了17.2%;玉米根部的谷胱甘肽-S-转移酶(GST)活性增加了191.8%;GST酶促反应动力学参数Vmax增大102.5%,Km减小40.0%。结果显示:R-28725能够提高氯磺隆处理后玉米中GSH的含量,增加GST和ALS活性,增强了玉米根部GST酶对底物的亲和力,缓解氯磺隆对玉米产生的药害。

日本看麦娘对氯磺隆、异丙隆和骠马的抗药性

在连续施用氯磺隆不同年限的麦田采集日本看麦娘种子.室内进行不同剂量的氯磺隆、异丙隆、骠马处理,测定日本看麦娘植株鲜重抑制率.连续施用氯磺隆5～6年后再施用异氯混剂(异丙隆与氯磺隆的混配剂)3～5年,日本看麦娘的抗性指数达325.80～613.40;麦田连续施用氯甲混剂(氯磺隆与甲磺隆的混配剂)3～4年、异氯混剂2～3年,日本看麦娘的抗性指数为15.22～42.45;对氯磺隆产生抗性的日本看麦娘种群(R1～R9)均对异丙隆、骠马敏感;连续施用骠马2～3年麦田的日本看麦娘种群对骠马未产生抗性.

绿黄隆在土壤中的迁移特性

应用土壤薄层层析（ＴＬＣ）法测定了１４Ｃ－绿黄隆在１０种土壤中的移动率，其Ｒｆ值为０．６５～１．０，表明绿黄隆在供试土壤中分别属可移动性和极易移动性。用大面积土柱淋溶法测得３种土壤柱在模拟降雨下的淋溶动态及其参数，经计算，在黄潮土、黄棕壤和红壤中，使１４Ｃ－绿黄隆垂直移动透过１０ｃｍ土层所需连续降水量分别为７５，８０和９４ｍｍ。绿黄隆在土壤中的迁移性与土壤ＰＨ值密切相关，随ｐＨ值增高其移动性和淋溶性增大。绿黄隆随水迁移性较强，它有可能对农业生态环境产生不良影响。

^(14)C-绿磺隆在土壤中的可提态残留、结合残留和矿化研究

本文对14 C 绿磺隆在 7种不同类型土壤中形成结合残留 ( 14 C ER)、可提态残留( 14 C ER)以及矿化为14 C CO2 的规律、影响14 C BR的主要因子及其在腐殖质中的分布规律等进行了研究。结果表明 :( 1 ) 14 C 绿磺隆在土壤中形成的14 C ER含量与土壤pH呈显著正相关 ,与土壤粘粒和有机质含量呈显著负相关 ,14 C ER中的绿磺隆母体化合物的消减满足一级反应动力学方程 ,其在 7种土壤中的半减期分别为 1 3 0～ 1 3 3 3d。pH是影响绿磺隆母体化合物降解的主要因子 ;( 2 ) 14 C 绿磺隆在 7种土壤中的14 C BR含量与土壤pH呈显著负相关 ,并与土壤粘粒含量呈显著正相关 ,土壤pH是14 C 绿磺隆在土壤中形成BR的主要影响因子 ;( 3 ) 14 C 绿磺隆形成的14 C BR主要分布在富啡酸和胡敏素中 ;14 C BR分布在胡敏酸中的相对百分比约为 2 % ,在14 C 绿磺隆BR的形成过程中 ,富啡酸的作用 >胡敏素 胡敏酸 ;( 4) 14 C 绿磺隆在 7种土壤中的14 C BR含量 ,在培养 2 0d内均随时间而快速增加 ,2 0d后变化量较小。 7种土壤中的14 C BR含量最大值分别占引入量的 53 5%、40 9%、3 7 8%、1 6 4%、42 5%、41 0 %和 3 1 3 % ;( 5)培养 90d内 ,14 C 绿磺隆通过三嗪杂环开环矿化为14 CO2 的量约占引入量的 4%～9% ,而土壤 1表明14

土壤残留氯磺隆和镉联合胁迫对菠菜代谢产物的影响

通过盆栽试验,评价土壤长残效期除草剂氯磺隆与重金属镉单一污染及复合污染对后茬作物菠菜生长、代谢产物的影响。基于GC-MS技术对3个不同处理组菠菜的代谢产物进行了辨识和分析。主成分分析结果表明,3个处理组的代谢物含量存在显著差异。具体表现为:1)与空白对照相比,氯磺隆诱导菠菜多种氨基酸、与能量代谢相关的3种糖类物质、苹果酸、γ-氨基丁酸、乳酸和腐胺的含量显著上升(*P<0.05);肌醇显著下降(*P<0.05);镉诱导菠菜多种氨基酸、与能量代谢相关的5种糖类物质、参与三羧酸循环的苹果酸和柠檬酸含量显著上升(*P<0.05);肌醇和腐胺含量显著下降(*P<0.05)。2)与单一污染相比较,复合污染诱导菠菜多种氨基酸,多种糖类物质和苹果酸等含量显著下降(*P<0.05)。由此可见,复合污染减弱了氯磺隆和镉单一污染时对氨基酸代谢和能量代谢的上调作用;氯磺隆和镉之间没有协同作用,相反对某些特定的代谢物存在拮抗作用。