DDT污染土壤的植物修复技术

本文报道用植草方法研究为DDT及其主要降解产物污染土壤的植物修复技术。在污染物的浓度为 0 .2 15mg/kg的土壤中 ,种植 10种草 3个月后DDT及其主要降解产物的总含量分别降低 19.6 %— 73.0 %。种植不同品种的草对土壤中污染物有不同的去除能力 ,其中以种植丹麦产的Taya草 (Per .ryegrass)与美国产的Titan草 (Tallfescue)为最强。用种植草的方法修复受DDT及其主要降解产物污染的土壤是一项可行的技术。在去除土壤中DDT的作用上 ,草的吸收是轻微的 ,只占原施药量的 0 .13%— 1.0 8% ,土壤中污染物消失的主要因素是土壤中生物降解作用的结果。     

DDT污染土壤的植物修复技术

本文报道用植草方法研究为DDT及其主要降解产物污染土壤的植物修复技术。在污染物的浓度为0．215mg/kg的土壤中，种植10种草3个月后DDT及其主要降解产物的总含量分别降低19．6％－73．0％。种植不同品种的草对土壤中污染物有不同的去除能力，其中以种植丹麦产的Taya草（Per.ryegrass）与美国产的Titan草（Tall fescue）为最强。用种植草的方法修复受DDT及其主要降解产物污染的土壤是一项可行的技术。在去除土壤中DDT的作用上，草的吸收是轻微的，只占原施药量的0．13％－1．08％，土壤中污染物消失的主要因素是土壤中生物降解作用的结果。     

表面活性剂强化植物-微生物联合修复双对氯苯基三氯乙烷污染土壤研究

通过实验对比研究植物(油菜)修复、微生物(甲基营养型芽孢杆菌(Bacillus methylotrophicus))修复、表面活性剂(聚氧乙烯山梨醇酐单硬脂酸酯(Tween 60))以及联合修复技术对双对氯苯基三氯乙烷(DDT)污染土壤的DDT去除效果。结果表明:以植物-表面活性剂-微生物共同作用下的DDT去除效果最好,土壤DDT去除率达到52.44%;油菜不仅可有效去除土壤中残留的DDT,同时只在地下部分对DDT进行了微量吸收,但没有进行转运,防止了农药在油菜可食部位的累积,保障了食品与生产安全。     

六六六、滴滴涕停用后对银川郊区蔬菜残留动态的初步探讨

一、前言 蔬菜如同粮食和水一样,是人们日常生活必不可少的食品,对于六六六(缩写BHC,下同)、滴滴涕(缩写DDT,下同)停止使用后,它们在土壤及作物中的残留动态已为世人所瞩目.为此我们选择了采样时已不再施用BHC、DDT的银川市郊区银新、红花二公社为点,对各类蔬菜及对应的土壤进行了检测,拟对停用BHC、DDT后,其异构体及代谢产物在各类蔬菜和对应土壤中的残留现状及其在菜地土壤中的消长动态,不同类蔬菜的吸收特性以及在蔬菜体内的转移动向等问题,进行初步探讨.这种     

典型污染场地中滴滴涕浓度空间变异性研究

利用经典统计学和地统计学相结合的方法,以某滴滴涕(DDT)粉剂生产企业为例,对污染场地中表层和地下5m处土样DDT浓度的空间变异性进行了研究。结果表明:表层和地下5m处土样DDT浓度经过对数转化后均通过了柯尔莫哥洛夫-斯蜜诺夫检验(K-S检验),能够很好地服从正态分布;表层和地下5m处土样DDT浓度的半变异函数拟合符合高斯模型,决定系数分别为0.8973和0.9348,由空间自相关引起的空间变异性分别占系统总变异性的99.11%和83.12%;用克里格插值法制出的DDT浓度等值线图能直观地反映表层和地下5m处土样DDT浓度的空间分布特征,DDT浓度呈现以原粉生产车间为中心向四周扩散的趋势,地下5m处土样DDT浓度空间分布与表层基本一致。     

六氯苯在中国典型持久性有机污染物污染场地中空间分布研究

在多年六氯苯生产车间及周围布设采样点,采取不同深度的土壤进行分析,研究持久性有机污染物(POPs)污染场地中六氯苯的空间分布规律.结果表明,生产车间附近污染严重,六氯苯的最高质量浓度为25 911.95 mg/kg,平均为4 944.07 mg/kg,在风力作用下六氯苯浓度向东南方向扩散;-3 m土层(以表土层为基准,表土层以下的土层深度为负值)中六氯苯最高质量浓度为369.63 mg/kg.平均为54.77 mg/kg,六氯苯浓度较表土层迅速下降,六氯苯污染中心位置与表土层对应;-5 m土层由于土壤类型为黏土或淤泥质黏土,六氯苯浓度相对于- m土层反而升高.平均质量浓度为92.13 mg/kg.纵观整个污染场地六氯苯的污染分布情况,污染中心位置向南移动,且六氯苯在垂直方向的迁移和浓度与土壤有机质含量相关.     

有机氯农药对珠江广州河段水质的污染情况

广州地区有机氯农药的生产和施用和全国其他地区一样,已有较长的历史.有机氯农药种类繁多,曾普遍施用而今引起人们关注的一般是666和DDT,进行环境监测和研究较多的也是666和DDT.几年来我站共采集珠江广州段水样四百多个,进行有机氯农药残留量的分析,通过对有关资料和数据的整理、研究,掌握了有机氯农药对珠江广州段水质的污染的基本情况,对该河段水质及环境的综合评价和研究、污染防治及水资源利用有一定帮助.     

环境条件对土壤中磺胺间甲氧嘧啶降解的影响

通过在实验室模拟不同的环境条件,研究常用兽药抗生素--磺胺间甲氧嘧啶(SMM)在土壤中的降解动态及其影响因素(如微生物和光照,土壤含水量、药物起始浓度等).结果表明,SMM在土壤中的降解遵循一级反应动力学方程.SMM在土壤中的降解主要是光降解和化学降解,微生物降解只占较小比例;土壤含水量的增加明显加快了SMM的降解速率,因而可以通过降低土壤中SMM残留浓度或提高土壤含水量等方法加速SMM的降解.以降低其对环境土壤和水体的风险;SMM的降解速率随土壤中SMM起始浓度增加而降低,表明土壤中降解微生物对SMM的浓度敏感.     

有机质对污染土壤中DDTs热脱附行为的影响

采用2种不同性质土壤(黑土和棕壤)作为供试土壤,利用DDT农药自配滴滴涕类(DDTs,包括p,p'-DDT、o,p'-DDT、p,p'-DDD、p,p'-DDE)污染土壤.采用热脱附方法,研究了原土及去有机质后土壤中DDTs在300℃,6个停留时间(5、10、20、30、40和50 min)下的去除率以及脱附后土壤中D...     

杀虫剂十氯酮的多介质环境行为模拟

应用EQC模型模拟十氯酮在多介质环境中的归宿和迁移通量.结果表明:土壤是十氯酮最大的贮存库,在稳态平衡条件下,残留率达到95.0%;在稳态非平衡条件下,十氯酮单独排放到水体,有37.5%残留在于排放的水体中,其在大气的浓度水平和质量分布均很低,在沉积物中的质量则来自于水体向沉积物的沉降迁移;十氯酮主要通过水体的水平迁移和土壤的厌氧降解输出;十氯酮的主要界面迁移过程是大气向土壤的迁移,其次是水体向沉积物的沉降和大气向水体的迁移.     

Effect of microbial activity, soil water content and added copper on the temporal distribution patterns of HCB and DDT among different soil organic matter fractions

Temporal changes in the distribution of exogenous HCB and DDT among different soil organic matter fractions were studied under sterile and non-sterile conditions, different soil water contents, and different concentrations of added Cu(2+). The residence time was 311days. Soil organic matter was fractionated into fulvic acid (FA), humic acid (HA), bound-humic acid (BHA), lipid, and insoluble residue (IR) fractions by a methyl isobutyl ketone (MIBK) method. Results revealed that there is a mass transfer tendency of DDT and HCB from FA, HA and BHA to IR and lipid fractions with increasing residence time. Microbial activity accelerated the mass transfer, while the addition of Cu(2+) slowed it down. The HCB and DDT transfer rate decreased as the soil moisture increased from 1.9% to 60%, but increased when soil moisture increased further to 90%. A two-compartment first order kinetic model was used to describe the mass transfer from FA, HA and BHA.     

气氛含氧量对DDT热处理特性的影响

滴滴涕属于有机氯农药,其所含成分DDTs在环境中难以降解,并具有生物毒性。利用高温管式炉研究气氛中含氧量对滴滴涕热处理特性的影响,为研发废弃滴滴涕高温热处理技术提供理论依据。实验结果表明,在600℃时,滴滴涕去除率最高为含氧量21%时的70.48%;在900℃条件下,当含氧量为21%时DDT去除率≥99%;在1 200℃条件下,当含氧量≥12%时DDT去除率≥99.9%。在滴滴涕热处理残渣中,o,p’-DDT占DDTs总量的比例在3个温度段中都随含氧量的增加而增长,DDT则都随含氧量增加而减少,且上述变化随温度升高而幅度加大。在尾气中,p,p’-DDE占DDTs总量的比例在3个温度段中都随含氧量增加而递增,在1 200℃条件下尤为明显。     

盐城滩涂土壤中六六六和滴滴涕的残留量测定

采集了盐城滩涂响水-滨海段化工园区周边区域内9个表层土壤样品,通过索氏提取土壤中的六六六(BHC)和滴滴涕(DDT)。最后通过带电子捕获检测器的气相色谱仪,定量分析了土壤中六六六和滴滴涕各异构体的含量及其百分比,以及六六六、滴滴涕的总含量,以了解该区域土壤中有机氯的当前含量水平和评估其潜在的环境毒害能力。结果表明,所有样品的六六六、滴滴涕总含量均远低于国家规定的土壤环境质量一级标准(50μg/kg)。     

Laboratory studies of dissipation of 14C‐DDT from soil and plywood surfaces

Abstract

The effects of temperature and solar radiation on dissipation of ¹⁴C‐p,p'‐DDT from a latosol soil were studied under laboratory conditions. Volatilization was measured by trapping organic volatiles during 6 weeks and was found to increase with rise of temperature from 3.8% of initial amount at ambient temperature to 5.9% at 45°C.

Studies on the effect of solar radiation using quartz tubes under sterilized and non‐sterilized conditions have shown that volatilized organics were highest in quartz tubes, with soil microflora presumably playing a very minor role in volatilization. Mineralization was shown to be low in sterilized systems and highest in non‐sterilized quartz systems. Studies on binding suggest that soil bioactivity may be involved in the formation of a portion of the bound residue. These laboratory experiments seem to support data from the field, where it is maintained that volatilization is a major mechanism for dissipation. Degradation in soil and to a lesser extent solar irradiation contribute also substantially to the dissipation mechanisms. Radiocarbon dissipated from plywood surfaces under indoor conditions in a biphasic fashion. Loss of 50% occurred after 5.5 weeks while the remainder dissipated at a very slow rate.     

Behaviour of DDT under laboratory and outdoor conditions in Germany

Abstract

Experiments were conducted on adsorption, volatilization and UV‐degradation of p,p'‐DDT on soil surface, and leaching and degradation in sand columns. p,p'‐DDT was shown to adsorb stronger to soils with higher organic content. UV irradiation at 290 nm for 10 hours mineralized less than 0.1% of DDT in soil.

Results show that only 0.1% of DDT volatilized in a sun‐exposed semi‐closed quartz system. Polar compounds accounted from 1.4% after 55 days. The rate of volatilization and degradation in an open system was much higher; only 15% DDT and 7% DDE were recovered after 6 weeks in the organic extract. p,p'‐DDT was adsorbed to a great extent on the top layers of sand columns; 86% in the top 8 cm.     

Contents and sources of DDT impurities in dicofol formulations in Turkey

Background, aim, and scope  Dicofol is widely used as a pesticide in agriculture applications. Since dicofol is mainly synthesized from dichlorodiphenyltrichlorethane (DDT), it contains DDT as an impurity. The European Community has forced Prohibition Directive 79/117/EEC to reduce DDT in dicofol formulations. Specifically, DDT content in a dicofol formulation cannot exceed 0.1%. The goal of this project was to determine the DDT content in dicofol formulations used in Turkey. Materials and methods  Samples of all the dicofol formulations in Turkey were collected to quantify DDT and DDT-related compounds. Four replicates were used for each sample. GC/MS/MS was used to analyze p,p′ and o,p′ isomers of DDT, DDD, and DDE. A HPLC was used to determine p,p′-Cl-DDT concentrations. Results  The total DDT content of the formulated dicofol was found between 0.3% and 14.3%. The concentration of p,p′-DDE ranged from 167 to 1,042 mg kg⁻¹ in dicofol samples. p,p′-DDT concentrations were found to be 32 to 183 mg kg⁻¹. The o,p’-DDT level ranged from 2 to 34 mg kg⁻¹ in the dicofol formulations analyzed. Discussion  It was estimated that 617.8 kg of DDT was released from dicofol. The main impurity was identified as p,p-Cl-DDT. Based on these results, dicofol serves as a continuing source of DDT contamination. Conclusions  All DDT concentrations in dicofol samples analyzed were higher than the permitted 0.1% level of Prohibition Directive 79/117/EEC. The reduction of dicofol is critical since it serves as a continual source of DDT contamination. Recommendations and perspectives  DDT has been found in soil, water, and air samples. Dicofol has been identified as a contributor to continued DDT contamination in soil and water. More studies are needed to ascertain the source of DDT in the air.     

Studies of the effects of temperatures and solar radiation on volatilization,mineralization and binding of 14c‐DDT in soil under laboratory conditions

Abstract

The effects of temperatures and solar radiation on the dissipation of ¹⁴C‐p,p'‐DDT from a loam soil was studied by quantifying volatilization, mineralization and binding. The major DDT loss occurred by volatilization, which was 1.8 times more at 45^oC than at ambient temperature (30°C). Mineralization of DDT slowly increased with time but it decreased slightly with increase in temperature. Binding of DDT to soil was found to be less at higher temperatures (35 and 45°C) as compared to ambient temperature. Degradation of DDT to DDE was faster at higher temperatures.

Exposure of non‐sterilized and sterilized soils treated with ¹⁴C‐DDT to sunlight in quartz and dark tubes for 6 weeks resulted in significant losses. Volatilization and mineralization in quartz tubes were more as compared to dark tubes. The volatilized organics from the quartz tubes contained larger amounts of p,p'‐DDE than the dark tubes. Further, higher rates of volatilization were found in non‐sterilized soils than in sterilized soils. The results suggest that faster dissipation of DDT from soil under local conditions relates predominantly to increased volatilization as influenced by high temperature and intense solar radiation.     

Bioavailable DDT residues in sediments: laboratory assessment of ageing effects using semi-permeable membrane devices

We describe the reduction in bioavailability of DDT in contaminated soil after it was incubated as sediment for 365 d. Bioavailability was assessed using semi-permeable membranes. Contaminated soils from three cattle dip sites, one spiked paired uncontaminated site, and one spiked OECD standard soil were studied. Sandy soil with residues of 1880 mg/kg summation operator DDT incurred since 1962, initially had 4.6% of summation operator DDT available, reducing to 0.6% following 365 d. Clay soil (1108 mg summation operator DDT/kg) had 4.1% initially available, reducing to 0.3% after 365 d. Freshly spiked soils had a greater amount of DDT initially available (10.9%), but this reduced to 1.5% by the end of the incubation. Of the DDT congeners, both o,p'-DDD and p,p'-DDD were most bioavailable in the soils, but also had the most significant decrease following incubation.     

DDT uptake by arbuscular mycorrhizal alfalfa and depletion in soil as influenced by soil application of a non-ionic surfactant

A greenhouse pot experiment was conducted to investigate the colonization of alfalfa roots by the arbuscular mycorrhizal (AM) fungus Glomus etunicatum and application of the non-ionic surfactant Triton X-100 on DDT uptake by alfalfa and depletion in soil. Mycorrhizal colonization led to an increase in the accumulation of DDT in roots but a decrease in shoots. The combination of AM inoculation and Triton X-100 application enhanced DDT uptake by both the roots and shoots. Application of Triton X-100 gave much lower residual concentrations of DDT in the bulk soil than in the rhizosphere soil or in the bulk soil without Triton X-100. AM colonization significantly increased bacterial and fungal counts and dehydrogenase activity in the rhizosphere soil. The combined AM inoculation of plants and soil application of surfactant may have potential as a biotechnological approach for the decontamination of soil polluted with DDT.