林丹对鼠的毒性

本文介绍了林丹的不同剂型、染毒量和给药方式对鼠类的毒性、中毒症状及其影响因素.     

林丹对人的毒性作用

本文根据自愿受试者、职业中毒、意外中毒和企图自杀接触林丹后的临床表现,结合理化检验,较全面地概括了林丹的中毒特征为呼吸加快,痉挛,惊厥,运动失常,口腔出血,昏迷,脑电图紊乱,谷丙及谷草转氨酶、乳酸脱氢酶等活性升高,肝脏出现脂肪性病变或损坏.但一般经过治疗均可恢复.     

林丹对鸟类和其它动物的影响

本文通过一些典型动物试验和离体培养试验,介绍了林丹对鸟类和哺乳类动物的毒性、中毒特征和某些作用机制.     

林丹致癌作用研究概况

本文通过启动、促成和作用方式的研究,较全面地详述了林丹对大、小白鼠的致癌危险性.大量结果证实,林丹对大白鼠既不能诱导肿瘤,亦无致癌作用,对小白鼠则有不同结果.有试验表明,当林丹使用剂量大于160mg/kg饲料时,有可能导致增生瘤或肝细胞腺瘤.如此高的剂量已超出了可忍受限度.机制研究表明林丹对小白鼠的致癌作用系非遗传机制.     

林丹的致敏、致畸和致突变作用

本文通过涂抹、口服、灌胃、注射、离体培养等方法的研究结果,全面的评价了林丹的致敏、致畸和致突变作用,尽管阳性与阴性结果均有报道,但基本结论是林丹对哺乳动物不存在致敏、致畸和致突变作用.     

林丹环境安全性评价研究

为了评价林丹在环境介质中的持久性,对林丹的土壤降解、水解、光解与快速生物降解性进行了试验研究。结果表明,林丹的土壤降解半衰期为36．9～68．6d,水解半衰期为8．94～2310d,对光反应稳定,难以快速生物降解。林丹对斑马鱼的96h—LC50为4．22μg·L^-1,对环境生物具有极高的毒性;林丹在金鱼体内的生物富集系数BCF〉1000,具有较高的生物富集性。根据试验结果推断,林丹在环境介质中具有极强的稳定性,很容易在食物链中发生生物积累。     

林丹在土壤中的残留动态研究

采用气相色谱法测定林丹在土壤中的残留动态。在自然状况下,林丹在土壤中的降解很快,２０ｄ后,灌淤土和灰漠土中降解率分别为３９９１％与４１２２％,两个月后降解分别达９９５９％和９９６９％。棉花种子及油菜种子经林丹拌种后,在土壤中的残留量很低,与不拌种的土壤残留相近。用干种子重量的０１５％林丹拌种,拌种棉田土壤中林丹的平均残留量为０００４２ｍｇ／ｋｇ,不拌种土壤中为０００２７ｍｇ／ｋｇ;油菜种子拌种土壤中平均残留量为０００３８ｍｇ／ｋｇ,不拌种的土壤中为０００１０ｍｇ／ｋｇ。棉花、油菜采用林丹拌种对土壤的污染是微不足道的。试验结果还表明,林丹在土壤中的残留量随用药浓度的提高而增加。     

林丹对微生物及水生生物的毒性

本文介绍了林丹对微生物和水生生物的毒性、中毒症状及潜在危险.     

水土流失社会经济因素作用机制分析

<正>严格地讲,在一定的相对稳定的地质时期内,水土流失受控于两种外力的作用,即涉及气候、地貌、植被、土壤等自然因素的外营力和人类活动.实际上,人类活动并不像地表径流等外营力那样直接参与侵蚀过程的发生,但人类活动的结果使水土流失过程发生了改变,使自然侵蚀过程大大加速.研究表明,在现代地质和气候未发生显著变化的情况下,人为活动特别是人为作用造成的天然植被的破坏是黄土高原现代水土流失加剧的根本原因;黄土高原土壤侵蚀的速率已由唐代以前7.9%的自然侵蚀速率上升到今天的25%.50年代我国的水土流失面积为153万km~2,1992年公布的遥感技术普查结果是水蚀面积179.4万km~2,40年来已治理53万km~2.也就是说,若不考虑其他原因,40年来以人类活动为主要原因的水蚀面积扩大了79万km~2.因此,人类不合理的社会经济行为是现代加速侵蚀的主导因素.     

根系分泌作用及其诱导机制

根系分泌作用及其实现植物对胁迫环境的适应，是近年来根际学领域的一个研究热点。文章评述了环境胁迫对植物根分泌物组成、含量的影响以及植物根系分泌的四种诱导假设；并对环境胁迫条件下的信号传递及根系分泌作用的生理及分子生物学基础进行了讨论。在此基础上，认为特定根分泌物的分泌是植物在进化过程中适应环境胁迫的实质。     

Lindane Biodegradation by Defined Consortia of Indigenous Streptomyces Strains

The current study aimed to compare lindane degradation by pure and mixed cultures of Streptomyces sp. Cell-free extracts were assayed for potentiating dechlorinase activity and, based on these results, consortia of two to six microorganisms were assayed for their growth on and degradation of lindane. Furthermore, the role of bacterial consortia of lindane-degrading strains was examined in lindane decontamination soil assays. Four actinobacteria, previously isolated from a pesticide-contaminated area, were selected because of their tolerance to lindane and their ability to use the pesticide as sole carbon source. These strains as well as Streptomyces sp. M7 and Streptomyces coelicolor A3 were used to study specific dechlorinase activity (SDA) and lindane removal in mixed cultures. Pure cultures presented SDA in the presence of 1.66 mg L^-1 lindane as carbon source. SDA was improved by certain mixed cultures until 12 times compared with pure cultures. Mixed cultures with two, three, and four strains showed maximum lindane removal of 46% to 68%, whereas combinations of five and six strains did not efficiently remove the pesticide from the culture medium. The Streptomyces sp. A2, A5, M7, and A11 consortium presented the lowest ratio between residual lindane concentration and SDA and could be a promising tool for lindane biodegradation.     

Lindane residues in the southern coastal aquifer of Israel

Water samples from twelve wells on the coastal aquifer of Israel were analyzed for γ-BHC (lindane), α-BHC, aldrin, o.p¹.DDD, p.p¹.DDT, dieldrin, heptachlor and heptachlor-epoxide. Lindane was found in five wells with concentrations ranging from traces to 15 ppt. α-BHC was detected in one well (4 ppt). None of the other pesticides could be detected. The wells where lindane was detected were between 13 m and 26 m deep and the soil above the water table was sandy. Lindane occurrence is attributed to heavy localized applications and downward movement of water in considerable quantities. Analysis of the potential mobility of lindane indicates that it can be rather mobile in sandy soils.