Dechlorination of DDT by Aerobacter aerogenes

Dechlorination of DDT to DDD in higher animals requires the presence of molecular oxygen, but in microorganisms the presence of oxygen hinders dechlorination. In cell-free preparations of Aerobacter aerogenes, the use of selected metabolic inhibitors indicated that reduced Fe(II) cytochrome oxidase was responsible for DDT dechlorination. This finding may possibly explain. the persistence of DDT residues in soils and sediments.     

北京市农田土壤中有机氯农药残留的空间分析

【目的】通过在北京平原区农田采取的131个表层土壤样品的化验分析，研究土壤中有机氯农药六六六（HCH）和滴滴涕（DDT）残留总量及异构体、代谢物含量的空间变异特征。【方法】样品测定结果采用传统统计分析，半方差结构和模型拟合的地统计分析以及结合普通Kriging 和反比距离插值方法进行分析。【结果】传统统计分析表明，土壤中残留HCH和DDT的异构体、代谢物及总量均服从对数正态分布，并全部属于强变异。基于半方差结构和模型拟合的地统计分析， -HCH、 -HCH和HCH总量没有空间变异结构方差，而其它农药含量存在空间变异结构方差、且可分别用指数模型或高斯模型拟合。模型拟合的结果看出α-HCH、DDT总量及其异构体以较大范围的变异为主（变程大于18 km），而 -HCH的变程只是2.73 km。趋势分析表明DDT的异构体、代谢物及总量都存在明显的趋势效应，而HCH及其异构体中只有 -HCH 和 -HCH略有趋势效应。结合普通Kriging和反比距离插值方法，获得了土壤有机氯农药残留含量的等值线图，并分析了其空间分布规律。【结论】所有土壤样本中的六六六含量和 85%的土壤样本的滴滴涕农药含量均达到国家《土壤环境质量标准》(GB15618-1995)一级标准（<0.05 mg·kg-1），残留污染较轻。     

DDT in the biosphere: where does it go?

The worldwide pattern of movement of DDT residues appears to be from the land through the atmosphere into the oceans and into the oceanic abyss. Calculations based on the fragmentary data available on. rates of movement and sizes of various pools of DDT residues lead to the conclusion that concentrations in the atmosphere and in the mixed layer of the oceans lag by only a few years behind the amounts of DDT used annually throughout the world. A model suggests that maximum concentrations of DDT residues occurred in air in 1966 and will occur in the mixed layer of the oceans in 1971. The biota probably contains in total less than 1/30 of 1 year's production of DDT during the mid-1960's, a very small amount in proportion to the total potentially available. The reason for the biota's failure to absorb larger quantities and to be affected much more severely is unclear. The analysis suggests that mere good fortune has protected man and the rest of the biota from much higher concentrations, thus emphasizing the need to determine the details of the movement of DDT residues and other toxins through the biosphere and to move swiftly to bring world use of such toxins under rational control based on firm knowledge of local and worldwide cycles and hazards.     

江西省不同利用方式土壤DDT残留特征及生态风险评价

[目的]探究江西省不同利用方式土壤DDT残留特征及生态风险。[方法]利用GC-ECD检测江西省7种不同利用方式土壤中的DDTs残留。比较了不同利用方式土壤DDT残留水平,分析了DDT来源,评价了DDT生态风险。[结果]7种不同利用方式土壤DDTs残留量整体处于较低水平,其平均残留量为0.37μg/g。7种不同利用方式土壤DDTs残留量：桔树生长地土壤〉水稻种植地土壤〉茶树生长地土壤〉河滩草地土壤〉蔬菜种植地土壤〉板栗树生长地土壤〉棉花种植地土壤。DDT组分中,仅p.p′-DDT被检出,这表明7种土壤均有新的DDT污染源输入。生态风险评价表明,7种不同利用方式土壤中的DDTs对该地区鸟类、土壤生物及哺乳动物的风险较低。[结论]DDT对江西省农产品质量安全和人类健康存在潜在的威胁。     

POISONING BY DDT: RELATION BETWEEN CLINICAL SIGNS AND CONCENTRATION IN RAT BRAIN

The severity of signs of poisoning in rats after a single dose of DDT is directly proportional to the concentration of the compound in their brains. The concentrations associated with death after one large dose are about the same as those after many smaller doses.     

河北省土壤中滴滴涕的残留量分析

采用快速溶剂萃取仪和气相色谱仪研究了河北省土壤中有机氯农药滴滴涕的残留状况.结果表明,河北省土壤中滴滴涕的残留量均值为51.52 ng/g,经对比相关标准,河北省土壤中的滴滴涕残留量处于较低的污染水平.     

吉林省蔬菜与水果中滴滴涕残留量分析

[目的]了解并掌握吉林省内蔬菜、水果中农药滴滴涕残留量的情况。[方法]依据GB/T5009.19-2008,采用气相色谱法进行检测。[结果]吉林省地区的蔬菜样品平均含量为2.03μg/kg,瓜类、水果样品平均含量分别为1.25、1.47μg/kg。[结论]按照《食品中农药最大残留限量》判断,4个地区的瓜果、蔬菜中滴滴涕农药的残留量较低,均未超过国家限值。     

固相萃取－气相色谱法测定小麦粉中六六六和滴滴涕残留量

[目的]建立小麦粉中六六六和滴滴涕农药残留量的固相萃取-气相色谱分析方法。[方法]以乙腈为提取剂,超声提取,采用Carbon NH2固相萃取柱净化,用乙腈-甲苯(3+1,V/V)作为洗脱液,经HP-1毛细管色谱柱分离后使用电子捕获检测器(ECD)测定。[结果]六六六和滴滴涕农药的质量浓度为0.005~0.400μg/m L时线性良好,相关系数为0.998 6~0.999 5。在0.05、0.10、0.20 mg/kg3个添加水平下,六六六和滴滴涕的加标回收率在80.21%~113.41%,相对标准偏差在1.30%~4.33%(n=6),检出限为0.10~1.51μg/kg。[结论]该方法具有样品前处理操作简单、灵敏度高、试剂用量少、重现性好等优点,适用于小麦粉中六六六、滴滴涕的定性定量分析。     

DDT residues and declining reproduction in the Bermuda petrel

Residues of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane] averaging 6.44 parts per million in eggs and chicks of the carnivorous Bermuda petrel indicate widespread contamination of an oceanic food chain that is remote from applications of DDT. Reproduction by the petrel has declined during the last 10 years at the annual rate of 3.25 percent; if the decline continues, reproduction will fail completely by 1978. Concentrations of residues are similar to those in certain terrestrial carnivorous birds whose productivity is also declining. Various considerations implicate contamination by insecticides as a probable major cause of the decline.     

Chlorinated hydrocarbon insecticides: root uptake versus vapor contamination of soybean foliage

The major environmental source of DDT (dichlorodiphenyltrichlo-roethane) residues in soybean plants arises from vapor movement from contaminated soil surfaces. In contrast, the presence of dieldrin, endrin, and heptachlor results primarily from root uptake and translocation through stems to leaves and seeds.     

Airborne particulates in Pittsburgh: association with p, p -DDT

The DDT associated with samples of airborne particulates was measured by gas chromatography. Because of possible vaporization of DDT during sampling, concentrations reported represent minimum values but demonstrate that DDT can be present in an urban atmosphere that is distant from any large-scale agricultural activity.     

Nitrogen source for a detritivore: detritus substrate versus associated microbes

Detritivores have been thought to derive nutrition from microbes associated with detrital particles and not from the nonliving plant substrate. The polychaete Capitella capitata, however, was found to derive a major portion of its nitrogen from the plant substrate when it feeds on detritus derived from seaweed. Microbes play a role as a nitrogen source for this detritivore when it feeds on detritus derived from marsh grass.     

川麦冬残留有机氯农药含量的测定与分析

[目的]测定四川道地药材—＂川麦冬＂中残留有机氯农药的含量,以评判川麦冬作为四川道地药材的质量情况,为川麦冬药材质量标准的制定提供了试验数据,也为三台县所产麦冬作为四川道地药材的用药质量提供了依据。[方法]以四川三台县所产川麦冬为材料,采用气相色谱法测定其总六六六（BHC）、总滴滴涕（DDT）和五氯硝基苯（PCNB）的含量。[结果]三台县所产川麦冬中残留有机氯农药含量均低于限量标准。[结论]从有机氯农药残留含量方面印证了川麦冬作为四川道地药材的优越性,符合国家中药材GAP标准和食品标准。     

DDT: interaction with nerve membrane conductance changes

The falling phase of action potentials of lobster giant axons is prolonged by DDT; finally a plateau phase is produced like cardiac action potentials. In axons poisoned with DDT, peak transient (sodium) currents associated with step depolarizations are turned off very slowly, and steady-state (potassium) currents are markedly suppressed. These two changes would cause the prolongation of action potentials and are considered the major ionic mechanisms of DDT action.     

不同产地莲子和莲子心中有机氯农药残留分析

[目的]检测10个不同产地莲子和莲子心中有机氯农药残留.[方法]样品采用超声提取-磺化法或超声振荡提取-Varian柱提取纯化,OV-17毛细管柱程序升温,外标法定量,GC-ECD测定了10个不同产地的莲子和莲子心中六六六4种异构体、滴滴涕4种异构体和五氯硝基苯共9种有机氯农药残留.[结果]9种有机氯农药在1～ 250 μg/L浓度范围内呈良好线性关系,平均加样回收率在93.21％～102.16％,10个产地的莲子心中未检测到有机氯农药残留,莲子中有机氯农药残留量远远低于《中国药典》标准.[结论]建立了一套简便、操作性强的莲子和莲子心中有机氯农药残留的分析方法.     

Dietary intake of pesticide chemicals. Calculated daily consumption of pesticides with foods are discussed and compared with currently accepted values

Residues of chlorinated organic pesticide chemicals were commonly found in all diet samples and all food classes within samples except beverages at a daily intake of 0.0014 mg per kilogram of body weight. Meat, fish, and poultry were the major source of pesticide residues and, when combined with dairy products, account for more than half of the intake of chlorinated organic pesticide chemicals. Fruits, garden fruits, and grain foods each accounted for about 10 percent of the intake of chlorinated pesticides. The DDT, its two analogs, dieldrin, lindane, and heptachlor epoxide account for 85 percent of the total intake of chlorinated pesticides. A single pesticide, DDT, accounts for one-third of the total. There was no statistically significant change in frequency or quantities of these compounds during this study. Frequency and quantities of the 14 additional chlorinated pesticides were too low to be meaningful.     

Photooxidation of DDT and DDE

The pesticide DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane] and its metabolite DDE [ 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene] can be photoOxidized in methanol. Photolytic generation of free radicals that may abstract hydrogen from solvent, react with oxygen, or abstract hydrogen from unreacted substrate occurs. Further decomposition of short-lived intermediates yields many compounds. Oxidation products include benzoic acids, aromatic ketones, and chlorinated phenols. The DDE also undergoes photocyclization to give dichlorofluorene derivatives.     

巢湖东半湖沉积物中有机氯农药的残留特征及风险评价

采样测定了巢湖东半湖4个样点的表层沉积物中有机氯农药(OCPs)的含量.结果表明,11种有机氯农药在样品中被检出,总含量为8.26～31.73 ng·g~(-1);OCPs在沉积物中的垂直分布从上往下大体呈递减趋势;且OCPs的最高含量都出现在上层沉积物中,说明巢湖东半湖沉积物中有机氯农药主要集中在0～3 cm的表层.根据分析,DDTs来自于早期残留或者施用农药后的长期风化残留.沉积物风险评估表明,巢湖东半湖表层沉积物中的有机氯农药存在一定的生态风险.     

辽宁植烟土壤重金属含量和农药残留量调查与评价

为了解辽宁植烟土壤重金属污染和农药残留状况,对辽宁省10个植烟县(市)土壤的As、Hg、Pb、Cd、Cr、Cu和Ni 7种重金属含量及六六六(HCH)和滴滴涕(DDT)2种农药残留量进行了测定与污染评价。结果表明,无论辽宁植烟区整体还是各个县(市),土壤重金属Cr、Ni、Cu、As含量均达到国家土壤环境质量一级标准,Hg含量均达到国家土壤环境质量二级标准;Cd、Pb含量整体分别达到国家土壤环境质量二级、一级标准,仅个别地区处于一级、二级标准。无论辽宁植烟区整体还是各个县(市),土壤HCH和DDT残留量均达到国家土壤环境质量一级标准。土壤中As、Hg、Pb、Cd、Cr、Cu、Ni及HCH、DDT的污染指数均小于1,重金属的内梅罗综合污染指数为0.60,农药的内梅罗综合污染指数为0.042,两者均小于0.7。可见,辽宁植烟土壤处于清洁水平,适合无公害农产品生产。     

同羊肉质的分析研究

对经放牧肥育屠宰的6只周岁羯同羊肉样中水分、粗蛋白质、粗脂肪、灰分、氨基酸、脂肪酸、胆固醇及有毒物质残留量等8项指标分析结果表明:同羊周岁羯羊肉的基本成分高于一般绵、山羊肉,尤以粗蛋白质以及对人体必需的氨基酸和有益的油酸含量颇高,而胆固醇含量低(尾脂又少于体脂),有毒物质残留量中,仅检出相当国家标准五分之一以下的“六六六”,无“滴滴涕”残留,符合国家食品卫生检验标准,可在产区内组织大批量的优质同羊肉生产。