二氰蒽醌在几种典型土壤中的降解吸附和移动特性

采用室内模拟试验方法,研究了二氰蒽醌在国内3种典型土壤江西红壤、东北黑土和太湖水稻土中的降解、吸附和移动特性。结果表明,25℃下二氰蒽醌在江西红壤、东北黑土与太湖水稻土中的降解半衰期分别为5.614、1.939、4.767d,其在土壤中化学稳定性较弱,易于降解,且pH越高,降解越快。二氰蒽醌在江西红壤的吸附等温线可以Freundlich方程很好地拟合,在东北黑土和太湖水稻土中的则可用线性方程拟合,吸附系数Kd值分别为36.4、114.6和51.9,Koc值分别为3 661.9、6 741.1、4 119.0,二氰蒽醌在土壤中具有中等或较强的吸附性能,在环境中迁移扩散的能力较弱。采用土壤薄层试验得到二氰蒽醌在这三种土壤中的移动分配系数Rf均<0.1,属于难于淋溶的农药,对地下水影响较小。二氰蒽醌在我国的几种典型土壤中均表现出了易降解性,难迁移以及难淋溶的特性,在目前的使用情况下,二氰蒽醌的环境风险较低。     

敌草胺在土壤中的吸附及其与持久性和生物有效性之间的关系（英文）

土壤吸附是农药在环境中归趋的关键支配因素,也是支配农药在环境中的持久性和生物有效性的重要因素之一。该文采用高效液相色谱法研究了除草剂敌草胺在不同性质土壤中的吸附、持久性和生物有效性以及吸附与土壤持久性、蚯蚓生物有效性之间的关系。结果表明,在供试浓度范围内,采用批量平衡技术测定的敌草胺土壤吸附等温线可用Freundlich模型表征(r0.99),土壤有机质含量(P0.01)是影响敌草胺在土壤中吸附的主要因素,其次为黏粒含量(P0.1)。敌草胺在土壤中的持久性较长,其降解过程符合一级动力学特征,降解速率随土壤有机质含量的升高而加快,半衰期(t50)在61.3-97.6 d之间;微生物对敌草胺在土壤中的持久性影响显著,微生物降解是敌草胺在土壤环境中降解的主要途径,灭菌处理后其在土壤中的半衰期延长了2.09~3.65倍。蚯蚓Eisenia foetida对敌草胺的吸收和生物积累也主要取决于土壤性质,特别是土壤的有机质含量水平(P0.05);敌草胺在土壤中的吸附系数与其半衰期(r=–0.885,P0.05)、生物积累因子(BAF)(r=–0.796,P0.05)之间均存在负相关关系,相应回归方程分别为t50=94.210–3.535 K_f和BAF=0.264–0.014 K_f,表明吸附系数可用作模型参数来评价敌草胺在土壤中的持久性和生物有效性。     

敌草胺在土壤中的吸附及其与持久性和生物有效性之间的关系

土壤吸附是农药在环境中归趋的关键支配因素,也是支配农药在环境中的持久性和生物有效性的重要因素之一。该文采用高效液相色谱法研究了除草剂敌草胺在不同性质土壤中的吸附、持久性和生物有效性以及吸附与土壤持久性、蚯蚓生物有效性之间的关系。结果表明,在供试浓度范围内,采用批量平衡技术测定的敌草胺土壤吸附等温线可用Freundlich模型表征（r>0.99）,土壤有机质含量（PPt50）在61.3-97.6 d之间;微生物对敌草胺在土壤中的持久性影响显著,微生物降解是敌草胺在土壤环境中降解的主要途径,灭菌处理后其在土壤中的半衰期延长了2.09~3.65倍。蚯蚓Eisenia foetida对敌草胺的吸收和生物积累也主要取决于土壤性质,特别是土壤的有机质含量水平（Pr=-0.885,Pr=-0.796,Pt50=94.210-3.535 Kf和BAF=0.264-0.014 Kf,表明吸附系数可用作模型参数来评价敌草胺在土壤中的持久性和生物有效性。     

苦参碱在土壤中的环境行为研究

农药在土壤中的吸附、移动及消解等特性是评价其环境安全性的重要指标。为评价植物源农药苦参碱对土壤环境的安全性,依据《化学农药环境安全评价试验准则》,探讨了苦参碱在东北黑土、江西红土、关中娄土及河南二合土等典型土壤中的吸附、移动、消解特性及其影响因素。结果表明:苦参碱在4类典型土壤中均为中等吸附、易移动,且土壤有机质含量与其吸附性呈正相关;在未灭菌条件(25℃,避光)下,苦参碱在4类6种不同土壤中的消解半衰期为4.1~9.8 d,而在灭菌条件下,半衰期为11.6~13.7 d,均为易降解。研究表明,苦参碱对土壤环境较为安全。     

绿磺隆在土壤中的放射性同位素残留分析

本文综述了利用同位素元踪法研究^14C-绿磺隆在土壤中的吸附、淋溶、迁移和降解等特性，分析了^14C－绿磺隆在土壤中的残留动态。     

环酰菌胺在土壤中的吸附及降解特性

为评价环酰菌胺在土壤中的生态风险,采用超高效液相色谱-串联质谱(UPLC-MS/MS)方法测定了土壤和水中环酰菌胺的残留量,研究了该农药在红壤和水稻土中的吸附及降解特性,并对其淋溶特性进行了分析,评估了该农药对地下水的污染风险。结果表明:环酰菌胺在红壤和水稻土中的吸附符合Freundlich吸附等温线方程,KOC值分别为373.69和726.86 mL/g,水稻土对环酰菌胺的吸附能力强于红壤。好氧条件下,环酰菌胺在红壤和水稻土中的降解半衰期分别为0.63和5.06 d,积水厌氧条件下的降解半衰期分别为6.80和9.24 d,表明环酰菌胺在好氧条件下降解较快。环酰菌胺在红壤和水稻土中的地下水污染指数(groundwater ubiquity score)分别为1.19和1.10,表明其对地下水的污染风险较低。结果可为环酰菌胺的生态风险评估提供参考。     

聚酰胺和聚甲基丙烯酸甲酯微塑料对异菌脲土壤环境行为的影响

微塑料可以吸附环境中的有机污染物,可能会影响农药在土壤中的降解、吸附和迁移等环境行为,其影响与微塑料和农药的类型有关。为明确微塑料对异菌脲在土壤中环境行为的影响,通过室内模拟试验,研究了聚酰胺 (PA) 和聚甲基丙烯酸甲酯 (PMMA) 微塑料对异菌脲在土壤中吸附、迁移、淋溶和降解的影响。研究结果表明:含2% (质量分数,下同) PMMA土壤和含2% PA土壤的土壤吸附常数 (K_f) 分别是对照土壤的2.9倍和1.2倍;在pH 4 ~ 7范围内,土壤对异菌脲的吸附容量随pH值的增加而增加;异菌脲在对照土壤、含2% PA土壤、含2% PMMA土壤中的比移值 (R_f) 分别为0.12、0.097和0.091,在第一段土柱中的含量分别为85.4%、100%和100%;异菌脲在对照土壤、含2% PA土壤和含2% PMMA土壤中的降解半衰期分别为19.8、26.7和40.8 d。研究表明,微塑料通过提高土壤对农药异菌脲的吸附能力,抑制了异菌脲在土壤中的迁移和淋溶,延长了其在土壤中的降解半衰期,因而可能会加剧其对表层土壤环境的威胁。     

磺酰脲类除草剂在土壤中的物理化学行为研究进展

综述了磺酰脲类除草剂在土壤中的吸附与解吸、降解、迁移等物理化学行为与土壤p H、有机质含量、黏粒含量等因素的关系,以及除草剂残留对后茬作物的影响。     

双唑草腈在3种典型土壤中的降解

为明确双唑草腈在环境中的降解行为特性,采用室内模拟试验方法,分别研究了积水厌气、好氧和灭菌条件下,双唑草腈在紫色土、水稻土及红壤3种典型土壤中的降解特性。结果表明:双唑草腈在3种土壤中的降解均符合一级反应动力学方程,好氧条件下,其在紫色土、水稻土及红壤中的降解半衰期分别为13.4、10.1和31.1 d,且降解速率与土壤中有机质和黏粒含量呈正相关;不同条件下的降解速率依次为积水厌气 > 好氧 > 灭菌,说明双唑草腈在土壤中的降解一定程度上受水解和微生物活性的影响;在一定的土壤持水量范围内,双唑草腈在土壤中的降解速率随土壤含水量增加而加快。研究表明,双唑草腈在稻田淹水条件下施用降解较快,残留期较短。所得结果可为双唑草腈的合理使用及其环境安全性评价提供科学依据。     

氟虫腈在三种土壤中的降解特性研究

实验室条件下,研究了氟虫腈在东北黑土、江西红壤和太湖水稻土中的降解特性。结果表明,氟虫腈在土壤中降解较慢,其在好气条件下的东北黑土、江西红壤和太湖水稻土中的降解半衰期分别为165、267和42 d,在渍水条件下的3种土壤中的降解半衰期分别为31、173和32 d。氟虫腈在pH 偏中性的太湖水稻土中降解最快;微生物对氟虫腈在土壤中的降解起主要作用;渍水条件有利于氟虫腈的降解,推测降解氟虫腈的微生物主要是厌氧菌属。     

环境条件和微生物对灭线磷降解的影响

环境条件和微生物影响灭线磷在土壤中的降解。随着土壤含水量和温度的增加,灭线磷的降解速度加快;微生物对灭线磷的降解有显著影响,30℃、含水量为40%条件下,未灭菌土中灭线磷的半衰期为16.6 d,灭菌土中灭线磷的半衰期为31.6 d;有机质对灭线磷的降解也有显著影响,有机质含量高,有利于灭线磷的降解;灭线磷在碱性土壤中的降解快于在酸性土壤中;30℃、含水量为40%条件下,灭线磷在3种土壤中的降解速度为:东北黑土＞广东红土＞山东砂壤土。     

实验室条件下威百亩及异硫氰酸甲酯在土壤中的降解特性

在实验室条件下,利用高效液相色谱研究了威百亩及其降解产物异硫氰酸甲酯在土壤中的降解特性及影响因素。结果表明:威百亩在土壤中的降解与土壤绝对含水量、环境温度和土壤有机质含量均密切相关。25 ℃下,威百亩在绝对含水量为0、20%、40%、60%的土壤中的半衰期分别为5.0、1.2、4.1和4.3 d,绝对含水量约为20%的土壤最有利于其降解。威百亩的降解速率还随温度的升高和土壤有机质含量的增加而加快。异硫氰酸甲酯的降解趋势与威百亩基本相同。研究结果可为威百亩的田间安全、合理施用提供参考。     

咪唑烟酸在不同土壤中的降解动态及其影响因子

研究了咪唑烟酸在小粉土、海涂土、黄筋泥及黄红壤4种不同类型土壤中的降解动力学,并探讨了土壤各性质对其降解的影响。结果表明:咪唑烟酸在4种土壤中的降解速率常数分别为 0.022 7、0.023 3、0.017 5、0.015 7,即在海涂土中降解最快,在黄红壤中降解最慢。土壤中影响降解的主要因子为有机质含量,其次为土壤酸碱度,即有机质含量越高,土壤碱性越强,则其半衰期越短,降解速度越快。外界环境条件对咪唑烟酸的降解影响也较大,温度越高,湿度越大,则咪唑烟酸的降解越快,温度效应系数(Q)的范围在1.08~1.42之间,与范特荷夫(Van,t Hoff)规则不吻合,说明温度对咪唑烟酸在土壤中降解速率的影响明显低于对水解的影响,最适的降解温度为25~35℃。与上述因子的影响相反,添加浓度高,则降解速率明显下降。     

环境条件对除草剂莎稗磷降解的影响

环境条件影响莎稗磷在土壤中的降解速度 :随着土壤温度的升高和含水量的增加 ,莎稗磷降解速度加快 ,在温度为 2 0、30和 4 0℃下 ,经过 10 d,莎稗磷的降解率分别为10 .4 %、2 6 .7%和 37.6 % ;在相对含水量为 30 %～ 110 %的土壤中 ,15d后莎稗磷降解 4 5.0 %～ 6 8.4 %。土壤中有机质能促进莎稗磷的降解 ,在有机质含量为 3.35%和 0 .55%的两种土壤中 ,莎稗磷的半衰期分别为 11d和 15d。莎稗磷在碱性土壤中比在酸性土壤中降解快 ,在偏酸性 (p H值为 6 .0 1)土壤中的半衰期为 2 2 d,在偏碱性 (p H值为 7.98)土壤中半衰期为 15d.     

Movement of fluometuron and 36Cl− in soil under field conditions: computer simulations

The movement of chloride ion and the movement and degradation of fluometuron in two soils of contrasting texture and structure was predicted with a simulation model which included terms for the degradation of fluometuron as a function of temperature and moisture. The simulated distributions of soil water, chloride ion and fluometuron were compared with the observations reported in a previous paper (Hance, Embling, Hill, Graham-Boyce & Nicholls, 1981), Soil waler contents and fluometuron distribution were simulated reasonably accurately. Movement of chloride to below 30 cm in both soils and degradation of fluometuron in the WRO sandy loam soil were not well simulated. The discrepancies between observed and predicted water contents and chloride distribution show the importance of measuring dynamic as well as static water properties. Therefore refined simulation models may need to account for pore continuity, soil particle movement and mobile and immobile categories of water.     

Degradation rates in soil of 1-benzyltriazoies and two triazole fungicides

The degradation rates in soil of 1-benzyltriazole together with six analogues having substituents in the phenyl ring and two commercial triazole fungicides, PP450 and triadimefon, were determined at 15°C and 20 % soil water content. The order of degradation rates of the benzyltriazoles was H > 4-OCH₃ > 4-F>4-Cl.4-≥tert-C₄H_g3,4-diCl>3-CF₃. Thus, in general, persistence was enhanced by electron-withdrawing substituents and by lipophilic groups that increased sorption by soil. Of the commercial fungicides, PP450 was degraded very slowly (half-life 578 days) while triadimefon was quickly converted (half-life 15 days) to the corresponding alcohol, triadimenol, which in turn was degraded very slowly. The effects of temperature and soil water content on rate of degradation were studied for 1-benzyltriazole and 1-(4-fluorobenzyl)triazole. The rate of degradation of 1-benzyltriazole was more sensitive to soil temperature and water content than was that of 1 -(4-fluorobenzyl)triazole. The influence of these results on the input data required by models which simulate persistence in field soil is discussed.     

Effect of pH on the degradation of atrazine,dichlorprop, linuron and propyzamide in soil

The rates of disappearance of atrazine, dichlorprop, linuron and propyzamide were measured in two soils incubated at 22°C and 80% water holding capacity. Observations were made at four pH levels in each soil. Atrazine degradation was relatively insensitive to pH; it increased slightly with increasing pH in one soil and decreased in the other. The other compounds all degraded more slowly at low pH in both soils although dichlorprop had essentially disappeared in 14 days under all conditions, so that the effect of pH is not unlikely to be of practical interest. The ratios of the degradation rates of atrazine, linuron, and propyzamide varied with the soil and the pH.     

Degradation and adsorption of 14C-MCPA in soil—influence of concentration, temperature and moisture content on degradation

MCPA was weakly absorbed in soils with 2.4, 3.0 and 2.9% humus. K_d-values were 0.7, 0.9 and 1.0, respectively. In soil, not previously treated with MCPA, the degradation of 0.05 mg kg^?114C-MCPA followed first-order reaction kinetics whereas degradation of 5 mg kg^?1 was only first-order for 2 weeks; exponentially increasing degradation rates followed indicating enrichment of the soil with MCPA decomposers. Degradation was monitored by evolution of ¹⁴CO₂. The influence of temperature on degradation of MCPA (4 mg kg^?1) could initially be described by Q₁₀ values or by the Arrhenius equation. After 1 day of incubation in two field soils Q₁₀ values were 3.3 and 2.9, respectively, between 0°C and 29°C; the activation energies were 87 and 76 kj mol^?1. Exponentially increasing degradation rates followed with doubling times of about 4.0, 1.8, 1.2 and 0.6 days at 6,10, 15 and 21°C, respectively. After 51 days of incubation, at temperatures between 6°C and 29°C, about 60%¹⁴C was evolved in CO₂ and only traces of MCPA were left in the soil. At 0°C and at 40°C only 1% and 10%¹⁴C, respectively, were evolved as CO₂ after 51 days. ¹⁴C-MCPA (4 mg kg^?1) was incubated at moisture contents from that in air-dried soil to 2.3 times field capacity. Optimum for degradation was from 0.6 to 1.2. field capacity. Degradation was very slow where water contents were below the level of wilting point and was nil in air-dried soil. In wet soil degradation was delayed, but even in water-logged soil (2.3 times field capacity) MCPA was decomposed after 4 to 5 weeks at 10°C.     

Prediction of field atrazine persistence in an allophanic soil with Opus2

A modified version of the model Opus was applied to measurements of soil water dynamics and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) persistence in a Bruntwood silt loam soil (Haplic Andosol, FAO system) in Hamilton, New Zealand. The modified model, Opus2, is briefly described and parameter estimation for the simulations is discussed. Soil water dynamics were more accurately described by applying measured soil hydraulic properties than by estimating them using pedotransfer functions. A parameter sensitivity analysis revealed that degradation was the most relevant process in simulating pesticide behaviour by Opus2. The Arrhenius equation incorporated in Opus2 did not correctly describe the effect of temperature on degradation rates obtained at 10, 20 and 30 degrees C. However, as the Arrhenius coefficient is a very sensitive parameter and soil temperature variation was relatively narrow in the field, the Arrhenius coefficient was approximated from the laboratory study. The simulation results obtained were superior to modelling at constant temperature. Field measured persistence of atrazine in the topsoil was underpredicted using the half-life determined in the laboratory at 10 degrees C. Modelling with a lag phase followed by accelerated degradation by use of a sigmoidal degradation equation in Opus2 significantly improved the modelling results. Nevertheless, degradation processes in the laboratory under controlled conditions did not accurately represent field dissipation, however well the laboratory degradation data could be described by simple kinetic equations. The study indicates the importance of improving field techniques for measuring degradation, and developing laboratory protocols that yield degradation data that are more representative of pesticide dynamics in field soils.