单甲脒盐酸盐等农药在土壤中的淋溶行为

本文用土壤柱淋溶法重点研究了单甲脒及其盐酸盐在土壤柱中的淋溶行为，以及田间试验的检测结果。同时与灭幼脲和涕灭威在土壤柱中的分布进行比较，研究表明，单甲脒、单甲脒盐酸盐和灭幼脲都不会污染地下水，而涕灭威则会对地下水构成严重的威胁。     

涕灭威等三种农药在土壤中的移动性

涕灭威、呋喃丹和拉索三种农药在土壤中的淋溶结果表明，经过３０ｃｍ土柱下渗到收集器中的涕灭威为８８．０％，呋喃丹为６９．１％，拉索为１．８４％；农药在四种土壤中的淋溶速度，砂土＞砂壤土＞粘壤土＞粘土；土壤性质对农药移动的影响比农药自身性质的影响要小。     

涕灭威农药的残留、毒性及其对生态环境的影响

本文描述了涕灭威农药在土壤、水体和生物中的残留、降解和归趋以及对生物的毒性。涕灭威是一种剧毒农药、在环境中虽能很快降解成亚砜,并能进一步降解成毒性更低的化合物,但它仍有可能造成对地下水的污染和对生物与人体的潜在危害。     

单甲脒等农药的土壤薄层层析行为

用土壤薄层层析法研究单甲脒，单甲脒盐酸盐、灭幼脲和涕灭威等农药在不同土壤中的迁移行为，分别获得了这几种化合物的Ｒｆ值，它们分别为０．１４、０．１７，０．０８，０．７６，研究表明，单脒，单甲脒盐酸盐和灭幼脲不会污染地下水，而涕灭威则会对地下水污染构成严重的威胁。     

运用SCI-GROW模型预测农药对地下水的污染风险

在对美国环境保护局开发的地下水暴露评价模型进行比较的基础上,选择SCI-GROW模型预测我国福建省甘蔗种植区5种常用农药对地下水的污染风险,并将模型预测结果与该地区地下水中农药的实测结果进行比较,对模型进行验证.结果表明,模型预测结果与实测结果之间具有很好的相关性,SCI-GROW模型能较好地用于我国东南沿海等地下水位较高、降水量较大、土壤砂性等地下水易受污染地区农药的筛选评价.最后,运用SCI-GROW模型预测涕灭威等17种我国常用农药对地下水的污染风险,为这些农药的科学使用提供参考.     

噻虫嗪在土壤中的吸附和淋溶特性

采用振荡平衡法、土壤薄层层析法和土柱淋溶法研究了噻虫嗪在砂土、粉砂壤土和砂姜黑土等3种不同理化性质土壤中的吸附和淋溶特性,探讨了农药的吸附与淋溶特性与土壤理化性质的关系以及剂型对农药淋溶特性的影响.结果表明,噻虫嗪在3种土壤中的吸附较好地符合Freundlich方程,Kd值分别为砂土1.25、粉砂壤土2.95、砂姜黑土5.10,其大小顺序与Koc值一致.黏粒含量是影响噻虫嗪在土壤中吸附性的最主要因素,有机质含量为次要因素.土壤薄层层析实验和土柱淋溶实验均表明噻虫嗪在3种土壤中的淋溶速率顺序为砂土粉砂壤土砂姜黑土,且油悬浮剂、水悬浮剂淋溶量较高,水分散粒剂次之,颗粒剂最低.噻虫嗪存在对地下水污染的潜在风险,特别是在黏粒和有机质含量低的环境下使用时,其风险应该引起足够的重视.     

人工甜味剂在不同类型土壤中的淋溶行为研究

人工甜味剂(artificial sweeteners)是一类人工合成或半合成的蔗糖替代品,广泛应用于食品、药物、个人护理品和饲料中,但是大多数人工甜味剂在人和动物体内几乎不被代谢而随尿液和粪便直接进入环境。在天津污水河沿线及甜味剂厂附近不同深度土层中检测到安赛蜜、糖精、甜蜜素和三氯蔗糖。为探讨人工甜味剂在土壤中的移动性及其对地下水污染的风险,应用土柱淋溶实验研究了安赛蜜和三氯蔗糖在2种土壤中的淋溶行为,并观测了人工甜味剂淋溶对土柱淋出液的溶解性有机质(DOM)、pH以及电导率(EC)的影响。结果表明安赛蜜和三氯蔗糖在2种土壤中表现出较强的移动性,超过87%的甜味剂均被淋出,只有不到13%的甜味剂被土壤截留或损失,因此对地下水具有较大的风险。安赛蜜和三氯蔗糖能够促进土壤溶解性有机质的溶出,但对淋出液的pH和电导率无显著影响。     

毒死蜱在土壤中的残留和淋溶动态

对土壤中毒死蜱的残留和淋溶动态进行了研究.结果显示,毒死蜱在土壤中的残留降解属于一级动力学反应,在土壤中的降解半衰期为63.0 d.通过土柱模拟淋溶试验,对毒死蜱在土壤中淋溶的影响因子进行了研究.结果表明,降水量对毒死蜱的淋溶影响较大,主要表现为降水水量增大, 毒死蜱在土层中的最大淋溶深度也随之增加, 出现浓度最高峰的土层深度也越大, 两者呈正相关关系.与降水量相比,降水强度对毒死蜱的淋溶的影响相对较小.     

杀虫双农药在土壤中行为的研究

本文研究了杀虫双的降解、吸附和田间淋溶情况。结果表明:杀虫双在pH3—9范围内的水解反应极为缓慢,杀虫双在土壤中的降解主要是微生物作用下的生物降解过程,杀虫双和沙蚕毒素在太阳光下的降解作用很快。土壤对杀虫双的吸附量很少,而沙蚕毒素较易被土壤所吸附。田间试验结果证实了杀虫双具有很大的淋溶趋势,应对该农药的地下水污染予以重视。     

涕灭威及其复合物对茎线虫DNA的影响

选择了一种毒性很高的氨基甲酸酯农药涕灭威、一种最常见的阴离子表面活性剂十二烷基苯磺酸钠(SDBS)及一种土壤中普遍存在的天然物质腐殖酸,组成两种复合污染体系;研究了它们对茎线虫的生态毒理效应和对DNA的影响.结果发现,涕灭威-SDBS复合体系在4 d内对茎线虫的DNA造成了明显的损伤,而涕灭威-SDBS-腐殖酸复合体系在8 d内对茎线虫DNA造成的损伤却远远低于未加入腐殖酸的复合体系.关于涕灭威及其复合污染物对茎线虫的生态毒理效应和对DNA损伤的研究尚未见文献报道.     

Atrazine leaching into groundwater: comparison of five simulation models

Five deterministic models (BAM, GLEAMS, HYDRUS, MOUSE and TETrans) were compared to evaluate, in first order of approximation, their ability to predict different soil vulnerabilities with respect to the atrazine leachability towards shallow groundwater. Two environmental scenarios were defined on the basis of the measured groundwater contamination. The former scenario corresponded to a vulnerable sandy loam soil, the latter to a moderately vulnerable sandy loam-organic soil. The pesticide was applied on both soils for corn weed control in early June 1986, while the groundwater samplings were made in February and September 1987. The small atrazine transport into groundwater through the sandy loam-organic soil, as it was detected from the groundwater sampling in late winter, was simulated only by TET rans model. With respect to the sandy loam soil vulnerability, satisfactory simulations were performed by both TETrans and HYDRUS. The applied herbicide was leached throughout this soil towards groundwater both in February and in September 1987. Conversely, atrazine leaching simulated by GLEAMS, MOUSE and BAM compared less consistently with the measured groundwater contaminations.     

微胶囊EDTA对2种土壤中铅释放的影响

选用不同铅污染程度及pH值的土壤,采用连续批浸提实验和土柱淋溶实验,比较研究微胶囊EDTA（Cap-EDTA）和未微胶囊化EDTA（Ncap-EDTA）对不同土壤溶液中pH值和铅离子浓度动态变化影响,以及土壤渗滤液中铅离子淋失特征。结果表明：施加2种不同形式的EDTA,可极显著地增加土壤溶液中铅离子浓度,Cap-EDTA能控制土壤溶液中铅浓度的突增幅度,且使土壤溶液中的铅持续保持在适度浓度的时间更长。同一种土壤不同处理间土壤pH值的变化趋势基本一致,无显著差异。施用2种不同形式EDTA可极显著地增加土壤渗滤液中铅离子含量,土壤铅累积淋失量呈对数曲线上升,但施用Cap-EDTA处理能显著降低土壤中铅的初始淋失量和淋失总量。在相同浓度及形式的EDTA下,高铅浓度和高pH值的土壤铅更易活化和淋失。因此,在进行污染土壤植物修复的EDTA调控时,采用微胶囊化EDTA,能降低其带来的污染地下水风险。     

Effect of natural organic matter on arsenic release from soils and sediments into groundwater

Arsenic (As) contamination in groundwater has received significant attention recently. Natural and anthropogenic sources contribute to the worldwide occurrence of As contamination. As speciation is an important factor related to its toxic and mobile behavior. The release of As from soils and sediments into groundwater is governed by several geophysicochemical processes, of which, As sorption behavior is of principle significance. This review paper summarizes existing information regarding the effects of natural organic matter (NOM) on the fate and mobility of As species in the environment. NOM may enhance the release of As from soils and sediments into the soil solution, thereby facilitating As leaching into the groundwater. The main influencing mechanisms include competition for available adsorption sites, formation of aqueous complexes, and/or changes in the redox potential of site surfaces and As redox speciation. NOM may also serve as binding agents, thereby reducing As mobility. However, comparably little research has been performed on this aspect. Since most investigations have been done on purified minerals under laboratory conditions, further research involving various geological materials under natural environmental conditions is required. Development of proper geochemical conceptual models may provide means of predicting the role of NOM in arsenic leaching and/or immobilization.     

Development and validation of a spectrophotometric method for soil adsorption study of malathion on three Indian soils

In view of the widespread use of pesticides in agriculture and its associated toxic effects on environment and human beings, the fate of these chemicals in soil is of major concern. The pesticide adsorption process is one of the major factors affecting its persistence and movement in the soil. With a view of studying the fate of malathion in soil, the adsorption of this insecticide was studied on three Indian soils by using batch equilibrium method. To carry out the adsorption study, a new simple, sensitive, and rapid method was developed, based on microwave-assisted alkaline hydrolysis of insecticide to the dimethyl dithiophosphate and its subsequent reaction with copper(I) perchlorate in acetonitrile. On mixing the reagents, a yellow color developed, which was stable for 120?min and was measured at 419?nm. The adsorption of malathion was studied by using Freundlich's adsorption equation and n _f values were observed less than 1 in all the soils. The leaching behavior of the insecticide was studied in terms of ground ubiquity score, which was below 1.8, classifying malathion as non-leacher pesticide, and hence it is not hazardous.     

Levels and distributions of organochlorine pesticides in the soil–groundwater system of vegetable planting area in Tianjin City,Northern China

To study the influence of long-term pesticide application on the distribution of organochlorine pesticides (OCPs) in the soil–groundwater system, 19 soil samples and 19 groundwater samples were collected from agricultural area with long-term pesticide application history in Northern China. Results showed that the composition of OCPs changed significantly from soil to groundwater. For example, ∑DDT, ∑HCH, and ∑heptachlor had high levels in the soil and low levels in the groundwater; in contrast, endrin had low level in the soil and high level in the groundwater. Further study showed that OCP distribution in the soil was significantly influenced by its residue time, soil organic carbon level, and small soil particle contents (i.d. <0.0002 mm). Correlation analysis also indicates that the distribution of OCPs in the groundwater was closely related to the levels of OCPs in the soil layer, which may act as a pollution source.     

农药在稻田使用对地下水的风险评估研究进展

农药风险评估可为农药登记和农药的环境安全管理提供重要的科学依据。水稻生产过程中病虫草害严重,农药使用品种多、频次高,田水存留时间长,对地下水污染风险高。开展农药在稻田使用对地下水的风险评估研究具有重要的现实意义。文章详细介绍了欧盟和美国的水稻-地下水风险评估研究进展,包括风险评估程序、暴露评估模型及暴露场景等。总结了我国农药在稻田使用对地下水风险评估的研究现状,并分析了我国研究的不足之处。在此基础上,提出了加强我国农药在稻田使用对地下水风险评估的建议。     

Biogeochemical transfer and dynamics of iodine in a soil–plant system

Radioactive iodide (¹²⁵I) is used as a tracer to investigate the fate and transport of iodine in soil under various leaching conditions as well as the dynamic transfer in a soil–plant (Chinese cabbage) system. Results show that both soils (the paddy soil and the sandy soil) exhibit strong retention capability, with the paddy soil being slightly stronger. Most iodine is retained by soils, especially in the top 10 cm, and the highest concentration occurs at the top most section of the soil columns. Leaching with 1–2 pore volume water does not change this pattern of vertical distributions. Early breakthrough and long tailing are two features observed in the leaching experiments. Because of the relatively low peak concentration, the early breakthrough is really not an environmental concern of contamination to groundwater. The long tailing implies that the retained iodine is undergoing slow but steady release and the soils can provide a low but stable level of mobile iodine after a short period. The enrichment factors of ¹²⁵I in different plant tissues are ranked as: root > stem > petiole > leaf, and the ¹²⁵I distribution in the young leaves is obviously higher than that in the old ones. The concentrations of ¹²⁵I in soil and Chinese cabbage can be simulated with a dual-chamber model very well. The biogeochemical behaviors of iodine in the soil-cabbage system show that cultivating iodized cabbage is an environmentally friendly and effective technique to eliminate iodine deficiency disorders (IDD). Planting vegetables such as cabbage on the ¹²⁹I-contaminated soil could be a good remediation technique worthy of consideration.     

未消化生活污泥中氮磷供应特性及其环境行为

采用土柱模拟试验，比较了生活污泥和化肥在水－旱耕作制下氮磷的肥效及其对地下水的影响。结果表明，污泥氮磷生物有效性在当季虽比等量的化肥略低，但仍有较大的肥效，且较化肥后效显著，有利于后茬作物的稳健生长。种水稻施用污泥或化肥都未发现有氮磷下渗现象；旱作条件下施化肥和污泥会产生较多的硝酸盐，且极易向下层土壤移动，但污泥的影响程度远没有化肥的大。作者认为在供试条件下按作物对养分的需要来施用污泥，不会构成氮磷对地下水污染的威胁。     

农药在土壤中归趋模型的研究进展

农药在土壤中的归趋模型是定量研究农药在土壤中分布和运移规律的主要手段 ,也是目前土壤环境学研究的重要内容之一 本文就几类常见的农药在土壤中的归趋模型作简要评述 ,分析它们的适用范围和局限性 ,并指出了今后的主要发展趋势和需要进一步研究的科学问题     

Environmental fate of pesticides used in Australian viticulture V. Behaviour of atrazine in the soils of the south Australian Riverland

The transport of the s‐triazine herbicide, atrazine, through the red, calcareous earth soils of the South Australian Riverland was investigated. Small, undisturbed soil cores were extracted from the inter‐row topsoil of a vineyard adjacent to the River Murray, approximately 10 km south‐west of Overland Corner, South Australia. The vines were grown in a deep (1–4 m) reddish brown, strongly alkaline, sandy loam with a low organic carbon content (<2%). Atrazine concentrations in the leachate were dependent on application rate and soil type. High application rates on subsoil gave high rates of leaching for a longer time compared to the same application rate on topsoil and/or lower application rates on either topsoil or subsoil. Overall, 37–65% of the applied atrazine was detected in the leachate from subsoil cores, 14–25% in topsoil core leachates. Small amounts of atrazine (< 10% of applied dose) were found only in the top 2 cm of the core profiles. The results suggest that this herbicide is somewhat mobile in such strongly alkaline, sandy loam soils and that the irrigated soils of this region are likely to be prone to leaching of atrazine, and therefore that groundwater supplies in this area may be at risk of contamination through use of triazine herbicides.