Zeta电位法研究除草剂在土壤胶体中的吸附

应用Zeta(ζ)电位法研究比较了扑草净和扑灭通在4种土壤胶体中的吸附.结果表明,当带有正电荷的除草剂在负电荷土壤表面吸附后,土壤表面的ζ电位有所增加,甚至使ζ电位从负转变成正.通过零电荷点计算得到除草剂和土壤之间的吸附常数和Gibbs自由能,并由经典的振荡平衡法得到相近结果.     

Adsorption of chloroacetanilide herbicides on soil and its components Ⅲ. Influence of clay acidity, humic acid coating and herbicide structure on acetanilide herbicide adsorption on homoionic clays

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite, soil humic acid, and their mixtures was studied by coupling batch equilibration and FT-IR analysis. Adsorption isotherms of acetochlor, alachlor, metolachlor and propachlor on Ca²⁺-, Mg²⁺ -. Al³⁺ -and Fe³⁺ -saturated clays were well described by the Freundlich equation. Regardless of the type of exchange cations, Kf decreased in the order of metolachlor ＞ acetolachlor ＞ alachlor ＞ propachlor on the same clay. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in binding, probably via H-bond with water molecules in the clay interlayer. The type and position of substitutions around the carbonyl group may have affected the electronegativity of oxygen, thus influencing the relative adsorption of these herbicides. For the same herbicide, adsorption on clay increased in the order of Mg²⁺ ＜ Ca²⁺ ＜ Al³⁺ ≤ Fe³⁺ which coincided with the iucreasing aciditv of homoionic clays. Acidity of cations may have affected the protonation of water, and thus the strength of H-bond between the clay water and herbicide. Complexation of clay and humic acid resulted in less adsorption than that expected from independent adsorption by the individual constituents. The effect varied with herbicides, but the greatest decrease in adsorption occurred at a 60:40 clay-to-humic acid ratio for all the herbicides. Causes for the decreased adsorption need to be characterized to better understand adsorption mechanisms and predict adsorption from soil compositions.     

Diurnal activity of soil-surface arthropods in agroecosystems: Design for an inexpensive time-sorting pitfall trap

The design for an inexpensive time-sorting pitfall trap is presented. The basis of the mechanism is a rotary stepping solenoid powered by lantern batteries. Traps were utilized to sample soil-surface arthropods at 2-h intervals for five 24-h periods in 1983. One trap was placed in a conventional tillage (CT) agroecosystem and one in a no-tillage (NT) agroecosystem. Soil arthropod surface activity was greatest in CT on 19 July during the dawn and dusk periods and during dusk on 27 June.     

Adsorption of chloroacetanilide herbicides on soil and its components Ⅲ. Influence of clay acidity, humic acid coating and herbicide structure on acetanilide herbicide adsorption on homoionic clays

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite, soil humic acid, and their mixtures was studied by coupling batch equilibration and FT-IR analysis. Adsorption isotherms of acetochlor, alachlor, metolachlor and propachlor on Ca2 + -, Mg2 + -. Al3 + -and Fe3 + -saturated clays were well described by the Freundlich equation. Regardless of the type of exchange cations, Kf decreased in the order of metolachlor ＞ acetolachlor ＞ alachlor ＞ propachlor on the same clay. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in binding, probably via H-bond with water molecules in the clay interlayer. The type and position of substitutions around the carbonyl group may have affected the electronegativity of oxygen, thus influencing the relative adsorption of these herbicides. For the same herbicide, adsorption on clay increased in the order of Mg2+ ＜ Ca2+ ＜ Al3+ ≤ Fe3+ which coincided with the iucreasing aciditv of homoionic clays. Acidity of cations may have affected the protonation of water, and thus the strength of H-bond between the clay water and herbicide. Complexation of clay and humic acid resulted in less adsorption than that expected from independent adsorption by the individual constituents. The effect varied with herbicides, but the greatest decrease in adsorption occurred at a 60:40 clay-to-humic acid ratio for all the herbicides. Causes for the decreased adsorption need to be characterized to better understand adsorption mechanisms and predict adsorption from soil compositions.     

Phytotoxicity of four herbicides on Ceratophyllum demersum, Vallisneria natans and Elodea nuttallii

The physiological effects of 4 herbicides (butachlor, quinclorac, bensulfuron-methyl and atrazine) on 3 submerged macrophytes (Ceratophyllum demersum, Vallisneria natans and Elodea nuttallii) were tested in laboratory conditions. The variables of the relative growth rate and the photosynthetic pigments content showed that all of the tested herbicides affected the growth of the plants obviously. The abnormal growth of the plants was observed in most treatment groups, even at the lowest concentration (0.0001 mg/L). Except for the C. demersum treated with quinclorac at 0.005 and 0.01 mg/L, the relative growth rates of the plants were inhibited significantly (p < 0.05). Statistical analysis of Chl-a content was carried out with both the t-test and one-way ANOVA to determine the difference between the treatment groups and control. The results showed that Chl-a contents of the plants in all treatment groups were affected by herbicides significantly, except for the C. demersum treated with bensulfuron-methyl at 0.0005 mg/L. The decrease content in Chl-a was positively correlated to the dosage of the herbicides in most treatment groups. It was suggested that herbicides in water body might potentially affect the growth of aquatic macrophytes. Since the Chl-a content of submerged macrophytes responded to the stress of herbicides sensitively and directly, it could be used as biomaker in environmental monitoring or in the ecological risk assessment of herbicide contamination.     

三种磺酰脲类除草剂在土壤中的降解及吸附特性

采用室内模拟试验方法,研究了氟胺磺隆、氯吡嘧磺隆和磺酰磺隆3种磺酰脲类除草剂在5种不同种类土壤(江西红壤、太湖水稻土、东北黑土、南京黄棕壤、陕西潮土)中的降解及吸附特性.结果表明,这3种磺酰脲类除草剂在这5种不同土壤中的降解速率均比较快,且降解过程均遵循一级动力学方程,土壤pH值是影响土壤降解速率的主要因素.3种磺酰脲类除草剂在土壤中的吸附均符合Frendlich模型,且具有较低的吸附容量.3种磺酰脲类除草剂在不同土壤中的吸附自由能变化均小于40kJ.mol-1,吸附主要以物理吸附为主,吸附常数随土壤pH值的增大而逐渐减小.     

Biodegradation of acetanilide herbicides acetochlor and butachlor in soil

The biodegradation of two acetanilide herbicides, acetochlor and butachlor in soil after other environmental organic matters addition were measured during 35 days lal)oratory incubations. The herbicides were applied to soil alone, soiI-SDBS (sodium dodecylbenzene sulfonate) mixtures and soil-HA (humic acid) mixtures. Herbicide biodegradation kinetics were compared in the different treatment. Biodegradation products of herbicides in soil alone samples were identified by GC/MS at the end of incubation. Addition of SDBS and HA to soil decreased acetochlor biodegradation, but increased butachlor biodegradation. The biodegradation half-life of acetochlor and butachlor in soil alone, soilSDBS mixtures and soil-HA mixtures were 4.6d, 6, ld and 5.4d and 5.3d, 4.9d and 5.3d respectively. The biodegradation products were hydroxyacetochlor and 2-melhvl-6-ethvlaniline for acetochlor, and hvdroxvbutachlor and 2,6-diethvlaniline for butachlor.     

Concentration and Recovery of Viruses from Water: A Comprehensive Review

Enteric viruses are a cause of waterborne disease worldwide, and low numbers in drinking water can present a significant risk of infection. Because the numbers are often quite low, large volumes (100–1,000 L) of water are usually processed. The VIRADEL method using microporous filters is most commonly used today for this purpose. Negatively charged filters require the addition of multivalent salts and acidification of the water sample to effect virus adsorption, which can make large-volume sampling difficult. Positively charged filters require no preconditioning of samples, and are able to concentrate viruses from water over a greater pH range than electronegative filters. The most widely used electropositive filter is the Virosorb 1MDS; however, the Environmental Protection Agency has added the positively charged NanoCeram filters to their proposed Method 1615. Ultrafilters concentrate viruses based on size exclusion rather than electrokinetics, but are impractical for field sampling or processing of turbid water. Elution (recovery) of viruses from filters following concentration is performed with organic (e.g., beef extract) or inorganic solutions (e.g., sodium polyphosphates). Eluates are then reconcentrated to decrease the sample volume to enhance detection methods (e.g., cell culture infectivity assays and molecular detection techniques). While the majority of available filters have demonstrated high virus retention efficiencies, the methods to elute and reconcentrate viruses have met with varying degrees of success due to the biological variability of viruses present in water.     

Adsorption kinetics of the herbicide safeners, benoxacor and furilazole, to activated carbon and agricultural soils

Chloroacetamide herbicides, namely acetochlor and metolachlor, are common herbicides used on corn and soybean fields. Dichloroacetamide safeners, namely benoxacor and furilazole, are commonly used in formulations containing chloroacetamide herbicides. Extensive reports on adsorption of chloroacetamide herbicides are available, yet little information exists regarding adsorption potential of co-applied safeners. Herein, the adsorption and desorption characteristics of selected herbicide safeners to granular activated carbon (GAC) and in agricultural soils are reported. Further, soil column studies were performed to understand the leaching behaviour of the herbicide Dual II Magnum. Equilibrium sorption experiments of safeners to three agricultural soils and one GAC showed that adsorption was best fitted by the Freundlich isotherm. The Freundlich adsorption constant, K_f, for benoxacor and furilazole sorption onto three agricultural soils ranged from 0.1 to 0.27 and 0.1 to 0.13 (mg/g) × (mg/L)?(1/n), respectively. The K_f for benoxacor and furilazole to GAC was 6.4 and 3.4 (mg/g) × (mg/L)?(1/n), respectively, suggesting more favorable sorption of benoxacor to GAC than furilazole to GAC. The sorption to soils was reversible as almost 40%–90% of both safeners was desorbed from three soils. These results were validated in four replicated soil column studies, where S-metolachlor was shown to leach similarly to the safener benoxacor, originating from the herbicide formulation. The leaching of S-metolachlor and benoxacor was influenced by soil texture. Cumulatively, these results show that safeners will move through the environment to surface waters similarly to the active ingredients in herbicides, but may be removed during drinking water treatment via GAC.     

L-半胱氨酸对酰胺类除草剂的离体脱氯反应与机制

研究了L-半胱氨酸与酰胺类除草剂的反应动力学、热力学及其机制.结果表明,L-半胱氨酸促进酰胺类除草剂的降解,该反应遵循二级动力学方程;除草剂降解速率同除草剂分子的亲电常数线性相关,降低顺序为甲草胺(kL-cysteine=7.65×10-3mol/(L×s))>乙草胺(kL-cysteine=7.23×10-3mol/(L×s))>丁草胺(kL-cysteine=6.01×10-3mol/(L×s))>S-异丙甲草胺(kL-cysteine=2.15×10-3mol/(L×s)),这与其土壤和高效菌降解速率顺序相一致;产物的质谱鉴定表明,L-半胱氨酸取代除草剂分子中氯原子.表明该反应为双分子亲核取代脱氯反应.热力学分析显示,该反应为焓控反应.除草剂间降解速率的差异性由熵变控制,且除草剂的降解速率与反应熵变(ΔS)具有良好的线性关系,ΔS数值越负,除草剂的降解速率越小.分子中N原子上的醚键取代基支链结构及链长度对反应速率影响较大,而芳环取代基结构没有明显影响.     

Combined effects of two sulfonylurea herbicides on soil microbial biomass and N-mineralization

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Adsorption and correlation with their thermodynamic properties of triazine herbicides on soils

IntroductionAdsorptionofherbicidesonsoilfromwaterisanimportantfactoraffectingtheirfate,biologicalactivity,andpersistenceinsoil watersystem .Itisoftenaffectedbyseveralpropertiesofsoil.Betterunderstandingofadsorptionanditsaffectingfactorswillmakeitpossibletoadjusttheherbicidedosageaccordingtosoilproperties,thusreducingtheenvironmentalpollutionofherbicidesintheenvironment.Fig .1　StructuresofthreetriazineherbicidesAmongthepost emergentherbicides,triazineherbicidesaremostcommonlyusedworldwideonco…     

Herbicide promotes the conjugative transfer of multi-resistance genes by facilitating cellular contact and plasmid transfer

The global dissemination of antibiotic resistance genes(ARGs), especially via plasmidmediated horizontal transfer, is becoming a pervasive health threat. While our previous study found that herbicides can accelerate the horizontal gene transfer(HGT) of ARGs in soil bacteria, the underlying mechanisms by which herbicides promote the HGT of ARGs across and within bacterial genera are still unclear. Here, the underlying mechanism associated with herbicide-promoted HGT was analyzed by detecting intr...     

黄河三角洲贝类增养殖区海水中16种除草剂污染特征及评价

本文以黄河三角洲贝类增养殖区为研究对象,选取3个典型区域,采用气相色谱-质谱法分析16种除草剂在海水中的污染状况和分布特征。结果表明,黄河三角洲贝类增养殖区海水中检出阿特拉津等10种除草剂,其中阿特拉津、扑草净、西草净、莠灭净、扑灭津和异丙甲草胺6种除草剂的检出率和平均检出浓度均较高;同区域7月海水中16种除草剂平均检出浓度的总量低于4月和10月;L区域16种除草剂平均检出浓度的总量低于H、K区域;聚类分析发现,扑草净、西草净和莠灭净的分布特征相似,异丙甲草胺与上述3种除草剂的分布特征不同,阿特拉津和扑灭津的分布特征不明显;生态风险分析发现,10月贝类增养殖区海水样品中阿特拉津、异丙甲草胺浓度存在中度风险,4月、7月和10月扑草净浓度存在中度生态风险。     

环境水体中三嗪类除草剂的SPME-GCMS联用仪测定

文章研究了固相微萃取-气相色谱/质谱联用技术测定环境水体中的11种三嗪类除草剂的方法.选择了以聚二甲基硅氧烷(PDMS)/二乙烯苯(DVB)和聚丙烯(PA)作为涂层材料的两种不同固相微萃取纤维对11种除草剂的萃取能力进行比较,PDMS/DVB萃取效果较好.为了提高萃取效果,分别从pH、解吸温度、萃取时间、盐效应等方面优...     

甲醇衍生法测定环境水体中八种酸性除草剂

文章建立了一种测定环境水体中8种酸性除草剂残留量的分析方法。1 000 mL样品在pH<2的情况下由乙醚分三次萃取后,萃取液经脱水,K-D浓缩至约1 mL,转移到衍生瓶中。在衍生瓶中补加2 mL正己烷、1 mL甲醇、8滴浓硫酸,80℃水浴加热1 h,进行甲醇衍生化处理,衍生后的样品运用气相色谱-质谱联用-分段选择离子扫描技术测定,内标法定量。结果表明:8种除草剂在0.05～2.5μg/L范围内线性均良好;方法灵敏度高,检出限均低于或等于0.02μg/L;方法的准确度和精密度高,在0.10、0.50、1.00、1.50μg/L添加水平下所有除草剂的回收率均在82.07%～116.99%之间,相对标准偏差RSD≤7.68%;经实际样品检测,可用于测定环境水体中酸性类除草剂的残留量。     

Application of an aerosol electrical mobility spectrum analyzer: Charged-particle polarity ratio measurement in the Antarctic and Arctic regions

An aerosol electrical mobility spectrum analyzer (AEMSA), developed at Hanyang University, was employed to investigate the particle charge characteristics in the Antarctic and Arctic regions. The particle charge characteristics in these areas were compared with the charging state in Ansan, South Korea, located in the midlatitude, where artificial factors, such as human activity, urbanization, and traffic, might result in a higher total concentration. Furthermore, in Ansan, South Korea, the charged-particle polarity ratio was very stable and was close to 1. However, notably different particle charge characteristics were obtained in the Antarctic and Arctic regions. The imbalance between the numbers of positively and negatively charged particles was evident, resulting in more positive charges on the atmospheric particles. On average, the positively charged particle concentrations in the Antarctic and Arctic areas were 1.4 and 2.8 times higher, respectively, compared with the negatively charged particles. The developed AEMSA system and the findings of this study provide useful information on the characteristics of atmospheric aerosols in the Antarctic and Arctic regions and can be further utilized to study particle formation mechanisms.     

取代脲类除草剂光催化降解动力学比较

为研究取代脲类除草剂在TiO₂光催化降解过程中的动力学规律,以非草隆、异丙隆和利谷隆3种取代脲类除草剂为研究对象,通过Langmuir-Hinshelwood动力学模型对其TiO₂光催化降解动力学进行模拟,并系统探讨了催化剂用量、C₀(取代脲类除草剂的初始浓度)、溶液pH、温度、ROSs(活性氧物种)和电子捕获剂等的影响. 结果表明:非草隆、异丙隆和利谷隆的TiO₂光催化降解均符合假一级动力学模型,其动力学常数分别为0.082 8、0.068 7和0.095 4 min-1;取代脲类除草剂分子中的芳香环和脲桥上的取代基对降解速率常数的大小有明显的影响. ROSs试验表明,非草隆、异丙隆和利谷隆光催化降解过程中分别有91.6%、95.5%和86.8%的贡献来自·OH;而光生空穴和其他ROSs的贡献相对较小,并且电子捕获剂BrO₃-和S₂O₈2-对取代脲类除草剂的降解动力学有显著的促进作用.      

农田土壤除草剂污染的修复技术研究进展

除草剂主要用于保护农作物免受杂草的侵害,是现代农业生产中用量最多的一类农药.然而,随着全球粮食需求的增加,除草剂的用量逐年增大,药效也不断增强,导致除草剂在农田土壤中出现累积、迁移转化和毒害作用等问题.为了降低除草剂给土壤-作物系统带来的生态风险,根据除草剂污染特征和区域农业生产规律研发绿色低碳修复技术,是目前生态环境领域需要关注的问题.基于此,整理了近年来关于农田土壤除草剂污染治理的相关报道,重点分析了修复技术的研究进展和应用案例,并对除草剂修复领域未来的发展动态进行了展望.目前应用于农田除草剂的修复技术主要有基于微生物修复、酶修复和植物修复的生物修复技术,以及基于生物炭基材料的吸附固定技术.其中,生物修复技术的发展相对成熟,已经应用于实际农田除草剂的修复治理工作,并形成了成功的修复案例.为了提升对农田土壤除草剂污染的修复效果,修复技术逐渐从单一模式向物理化学-生物多技术耦合模式发展,以充分发挥多技术集成应用的协同作用.     

水中典型含氮有机物氯化生成消毒副产物的潜能研究

选取了受污染原水中广泛存在的12种含氮有机物（除草剂、杀虫剂、氨基酸、工业品等）,开展了氯化和氯胺化培养生成典型消毒副产物的实验,目的是通过对水中脲类除草剂、嗪类除草剂和其他含氮化合物培养生成不同消毒副产物的生成量,讨论不同种类含氮化合物生成含碳和含氮消毒副产物规律以及考察不同消毒副产物的可能前体物.研究发现,脲类除草...