Toxic effects of acetochlor and methamidophos on earthworm Eisenia fetida in phaiozem, northeast China

Acetochlor and methamidophos are two important agrochemicals which are widely applied to agricultural production in northeast China. The investigation on the earthworm Eisenia fetida as an important type of soil animals exposed to single and binary-combined contamination of acetochlor and methamidophos was thus carried out. The single toxic effect test showed that the two agrochemicals had their toxicity to the earthworms living in phaiozem. Acetochlor had a stronger acute toxic effect on the earthworms than methamidophos. The mortality of the earthworms exposed to individual acetochlor and methamidophos changed with an increase in the exposure time and the exposed concentrations. The LD50 value of acetochlor and methamidophos toxic to the earthworms was 115.6-275,3 and 29.5-228.6 mg/kg, respectively. The weight of the earthworms was a more sensitive index compared to the mortality in indicating toxic effects of acetochlor and methamidophos in phaiozem. When considering both the mortality and the body-weight change, the combined pollution of acetochlor and methamidophos in phaiozem resulted in their synergic toxic effects on the earthworms.

Single and joint stress of acetochlor and Pb on three agricultural crops in northeast China

In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.

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 laboratory incubations. The herbicides were applied to soil alone, soil 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, soil SDBS mixtures and soil HA mixtures were 4.6d, 6.1d and 5.4d and 5.3d, 4.9d and 5.3d respectively. The biodegradation products were hydroxyacetochlor and 2 methyl 6 ethylaniline for acetochlor, and hydroxybutachlor and 2,6 diethylaniline for butachlor.

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.

Adsorption-desorption behavior of acetochlor to soils in the presence of some environmental substances

The behavior of herbicide acetochlor adsorption desorption to soil in the presence of humic acid (HA), anionic surfactant sodium dodecylbenzene sulfonate (SDBS), cationic surfactant hexadecyltrimethyl ammonium bromide (HDAB) and NH 4NO 3 as a chemical fertilizer was studied. Observed acetochlor adsorption isotherm were well described using Freundlich isotherm equation, from which the desorption isotherm equation has been deduced. The deduced equation can more directly describe acetochlor desorption process. The results showed that the enhance of acetochlor adsorption capacity by solid HA was greater than by soluble HA. The presence of NH 4NO 3 can slightly enhance acetochlor adsorption to soil by comparison with that measured in NH 4NO 3 free solution. In soil water system, surfactant acetochlor interaction is very complex, and the surfactant adsorptions as well as acetochlor adsorption need to be considered. When acetochlor soil suspensions contained lower concentration SDBS or HDAB (40 mg/L), K f for acetochlor adsorption was decreased in comparison to that measured in SDBS or HDAB free solution. When acetochlor soil suspensions contained higher concentration SDBS or HDAB (corresponding 1400 mg/L or 200 mg/L), K f for acetochlor adsorption was increased in comparison to that measured in SDBS or HDAB free solution.

Impact of acetochlor on ammonia-oxidizing bacteria in microcosm soils

Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and community composition of AOB in soil amended with three concentrations of acetochlor (50, 150, 250 mg/kg) and the control (0 mg acetochlor/kg soil) in a microcosm experiment by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and the phylogenetic analysis of excised ...

Photodegradation of acetochlor in water and UV photoproducts identified by mass spectrometry

The sunlight photodegradation half-lives of 20 mg/L acetochlor were 151, 154 and 169 days in de-ionized water, river water and paddy water, respectively. When exposed to ultraviolet (UV) light, acetochlor in aqueous solution was rapidly degraded. The half-lives were 7.1, 10.1, and 11.5 min in de-ionized water, river water and paddy water, respectively. Photoproducts of acetochlor were identified by gas chromatography/mass spectrometry(GC/MS) and found at least twelve photoproducts resulted from dechlorination with subsequent hydroxylation and cyclization processes. The chemical structures of ten photoproducts were presumed on the basis of mass spectrum interpretation and literature data. Photoproducts are identified as 2-ethyl-6-methylaniline; N,N-diethylaniline; 4,8-dimethyl-2-oxo-1,2,3,4- tetrahydroquino-line; 2-oxo-N-(2-ethyl-6-methylphenyl)-N-(ethoxymethyl)acetamide; N-(ethoxymethyl)-2′-ethyl-6′-methylformanilide;1-hydroxyacetyl-2-ethoxyl-7-ethylind ole; 8-ethyl-1-ethoxymethyl-2-oxo-1,2,3,4-tetrahydroquinoline; 4,8-dimethyl-1-ethoxymethyl-2-oxo-1,2,3,4-tetrahydroquinoline; 2-hydroxy-2′-ethyl-6′-methyl-N-(ethoxymethyl)acetanilide and a compound related to acetochlor. The other two photoproducts were detected by GC/MS although their chemical structure was unknown.

Single and Combined Effects of As (Ⅲ) and Acetochlor on Phosphatase Activity in Soil

The actions and interactions of acetochlor and As on the soil phosphatase activity were investigated after 1, 3, 6, 10, 15, 30 and 60 d of exposure under control conditions. The soils were exposed to various concentrations of acetochlor and As individually and simultaneously. The results showed that acetochlor, As only, and combined pollution all clearly inhibited soil phosphatase activity. The maximum inhibition ratios of soil phosphatase activity by acetochlor, As only and combined pollution were 36.44, 74.12 and 61.29%, respectively. Two kinetic models, ν=c/（1＋bi） （model 1） and ν=c（1＋ai）/（l＋bi） （model 2）, were used to describe the relationship between the concentrations of As and acetochlor and the activity of soil phosphatase. The semi-effect dose （ED 50 ） values induced by As and acetochlor stress based on the inhibition of soil phosphatase were 18.1 and 33.11 mg kg-1, respectively, according to calculation by model 1. The interactive effect of acetochlor with As on soil phosphatase primarily consisted of significant antagonism effects at the higher concentrations tested. The step regression results show that the toxicity order was As （III）〉acetochlor〉As （III）×acetochlor throughout the incubation period.

Effect of herbicide acetochlor on cytochrome P450 monooxygenases and GST of earthworms Eisenia fetida

To assess the sublethal toxicity of the herbicide acetochlor to earthworms and to find out biomarkers possible inducted under acetochlor exposure, Eiseniafetida was exposed to artificial soils supplemented with different concentrations of acetochlor（5, 10, 20, 40 and 80 mg/kg soil）. Effects of the acetochlor on cytochrome P450 monooxygenases p-nitroanisole O-demethylase（ODM）, aldrin epoxidase（AE） and glutathione-S-transferases （GSTs） activities were determined. The results revealed cytochrome P450 monooxygenases were elevated with increasing concentrations of acetochlor, and the AE activity increased significantly compared with control at the concentration of 80 mg/kg （P〈0.05）. However, ODM activity from E. fetida was not induced significantly by acetochlor at all treatments（P〉0.05）. Sodium dodecyl sulfate-polyacryamide gel electrophoresis（SDS-PAGE） showed that one protein band was visualized and no evident differences were found in protein profiles between treatments and control. The GST activity increased significantly with longer duration（P〈0.05） and increasing concentrations of acetochlor exposure（P〈0.05）. This study showed that the monooxygenases and GSTs activities in E. fetida could be induced by acetochlor, and thus, the AE and GST could be used in sublethal assays for soil contamination surveys and GST could be used as biomarkers of acetochlor exposure in E. fetida.

Bioremediation of Acetochlor in Soil and Water Systems by Cyanobacterial Mat

This study investigated the bioremediation of organic pollution in soil and water systems by cyanobacterial mats collected from Wadi Gaza. Acetochlor, a model compound of herbicide, was used as a standard organic pollutant. Various concentrations of acetochlor were injected in soil and water samples pre-treated with cyanobacterial mat for several periods of time. Percentage of growth of wheat as a test plant was taken as indicator of bioremediation of acetochlor. Results showed that acetochlor was degraded in both soil and water systems. Degradation was?much?faster in the water system than in the soil system. Concentrations of acetochlor above the field rate did not affect the bioremediation process in the water system whereas it did in soil pots. Furthermore, bioremediation in water system was nearly completed in 15 days whereas it did not reach high percentage?in the soil system. These encouraging results are new contribution in field of bioremediation of pesticide by cyanobacterial mats and suggest that application of cyanobacterial mat could be a fast and suitable methodology for bioremediation of organic pollutant in the ecosystem.

Adsorption of phenthoate and acetochlor from water by clays and organoclays

Adsorption of phenthoate and acetochlor onto kaolin, montmorillonite, bentonite clays and respective organoclays prepared by the exchange of quaternary ammonium as tetradecyltrimethyl ammonium bromide(TTAB), dodecyltrimethylammonium bromide(DTAB), and cetylpyridinium chloride(CPC) were studied. The adsorption equilibrium data points were fitted to Freundlich isotherm equations. The adsorption of phenthoate and acetochlor were significantly enhanced by surfactant treatment of the clays. The amount of both pesticides adsorbed per unit mass of organoclay followed the order of TTA-kaolin < TTA-montmorillonite < TTA-bentonite, which is inconsistent with the organic carbon content of the clays. The removal efficiency of organomontmorillonite to treat acetochlor is in the order of CP(C 16 )-montmorillonite > TTA(C 14 )-montmorillonite > DTA(C 12 )-montmorillonite. Phenthoate is adsorbed to greater extent than acetochlor by each adsorbent, which may be due to the higher hydrophobicity of phenthoate, indicating considerable hydrophobic interaction between adsorbent/adsorbate systems.

Study on the Toxicity of Acetochlor to Loaches

[Objectives] This study was conducted to investigate the toxic effect of acetochlor in loaches. [Methods]Loaches were put into the acetochlor solution with concentrations of 0,0. 062 5,0. 125,0. 25,0. 5 and 1 μl/L,respectively. The effects on dismutase( SOD),peroxidase( POD),catalase( CAT) and glutathione( GSH) activity and malondialdehyde( MDA) content in the liver of loaches were analyzed after 12,24,48 and 72 h of exposure. [Results] The activity of SOD,POD,CAT and GSH increased with the stress time and concentration,reached their maximums at 48 h after acetochlor treatment,and then decreased.However,MDA content increased with the stress time and concentration. [Conclusions] Acetochlor had obvious oxidative stress on loaches,and the activity of SOD,POD,CAT and GSH showed an obvious induction-inhibition effect with the increase of acetochlor concentration and the extension of stress time.

Effects of Acetochlor and Methamidophos on Fungal Communities in Black Soils

Using plate counting and ergosterol assay, single and joint effects of acetochlor and methamidophos on the dynamicsof soil fungal population and total fungal biomass in the black soil zone of Northeast China were investigated. The resultsdemonstrated that acetochlor at high concentration levels (150 and 250 mg kg-1) had an acute and mostly chronic toxicityon both the soil fungal population and total fungal biomass, but at a low concentration (50 mg kg-1) generally had astimulating effect that was stronger with total fungal biomass than with the soil fungal population. Methamidophos ata high concentration level (250 mg kg-1) alone and almost all of its combinations with various dosages of acetochlorincreased the soil fungal population, whereas at most sampling dates with 250 mg methamidophos kg-1 soil, total fungalbiomass increased, but in combination with acetochlor it was decreased in the early period of incubation and then increased28 days after incubation. Thus, through measuring the number of colony forming unit of the soil fungal population alongwith the total fungal biomass, a better understanding on effects of agrochemicals on soil fungi could be made.

耐乙草胺促生菌筛选及其对玉米幼苗的促生效应

分离筛选具有耐乙草胺特性的促生菌株,并对其进行菌种鉴定,可为推进多功能微生物菌剂的研发提供可行性方案和理论依据。本研究利用不同浓度乙草胺的改良培养基筛选出具有高耐乙草胺能力的菌株,测试其在不同培养基条件下的促生作用,并通过促发芽试验和盆栽试验验证可行性。结果表明:菌株JL7与JL16为高耐乙草胺且具有较强促生能力的根际促生菌,两株菌对乙草胺的最大抗性浓度达700 mg·L^(-1)。JL7的溶磷能力高达223.21 mg·L^(-1),产IAA(吲哚乙酸)量达82.40 mg·L^(-1)。经鉴定JL7菌株为肠杆菌属(Enterbacter sp.),JL16菌株为醋菌属(Acetobacter sp.)。促发芽试验结果表明,施入JL7与JL16菌株72 h后发芽率分别较对照提高9.42、3.84个百分点,且JL16菌株对芽长与根长有显著的促生作用,较对照增加52.53%、23.22%。盆栽试验中,JL7与JL16的添加对株高、茎粗、根直径、根长等植株形态指标均表现为促进作用,并证实菌株JL7、JL16在土壤中仍对乙草胺具有耐受性。两种耐乙草胺菌株在促生方面具有显著效果,这为后期微生物改良土壤和开发新型微生物肥料提供了菌种资源和理论基础。

Spatial and temporal distribution of acetochlor in sediments and riparian soils of the Songhua River Basin in northeastern China

The Songhua River Basin is a burgeoning agricultural area in the modern times in China. Particularly in recent years, increasing chemical fertilizers and pesticides have been applied with the development of agricultural production. However, the situation of non- point source pollution （NSP） from agricultural production in this basin is still obscure. In order to solve the problem, the occurrence and distribution of acetochlor in sediments and riparian soils of the Songhua River Basin before rain season and after rain season were investigated. In addition, total organic carbon was analyzed. The result showed that the concentration of acetochlor ranged from 0.47 to 11.76 μg/kg in sediments and 0.03 to 709.37 μg/kg in riparian soils. During the high flow period in 2009, the mean concentration was 4.79 μg/kg in sediments and 0.75 μg]kg in riparian soils, respectively. Similarly, the mean concentration was 2.53 μg/kg in sediments and 61.36μg/kg in riparian soils, during the average flow period in 2010. There was a significant correlation between the concentration of acetochlor and total organic carbon in surface sediments. Moreover, the distribution of acetochlor in sediments of the Songhua River was significantly correlated to land use and topography of the watershed. The investigated data suggested that the concentration of acetochlor in the Songnen Plain and the Sanjiang Plain was higher than that in the other areas of the basin, and riparian buffering zones in these areas bad been destroyed by human activities. The optimal agricultural measures to alleviate the contamination of pesticides should be adopted, including controlling agricultural application of acetochlor and ecological restoration of riparian buffering strips.

Application of the health risk assessment of acetochlor in the development of water quality criteria

Acetochlor is a widely used herbicide in agricultural production. Studies have shown that acetochlor has obvious environmental hormone effects, and long-term exposure may pose a threat to human health. To quantify the hazards of acetochlor in drinking water, a health risk assessment of acetochlor was conducted in major cities of China based on the data of acetochlor residue concentrations in drinking water. The approach of the Species Sensitivity Distributions(SSD) method is used to extrapolate from animal testing data to reflect worst case human toxicity. Results show that hazard quotients related to acetochlor residues in drinking water for different age groups range from 1.94 × 10-4 to 6.13 × 10-4, so, there are no indication of human risk. Compared to the total estimated hazard quotient from oral intake of acetochlor, the chronic exposure imputed to acetochlor residues in drinking water in China accounts for 0.4%. This paper recommends 0.02 mg/L to be the maximum acetochlor residue concentration level in drinking water and source water criteria.

乙草胺、扑草净、2,4-滴异辛酯在春玉米中的残留及膳食风险评估

为评价乙草胺、扑草净、2,4-滴异辛酯在春玉米上施用后可能产生的膳食暴露风险,通过规范的田间残留试验,检测春玉米中乙草胺、扑草净、2,4-滴异辛酯的残留量,结合中国的国家估算每日摄入量(NEDI)与可接受的每日摄入量(ADI),评估这些农药的风险商(RQ)。在0.01~0.55 mg/kg添加水平下3种有效成分及代谢物在青玉米、玉米、青玉米秸秆和玉米秸秆中的平均回收率为88%~113%,相对标准偏差为0.4%~8.6%。开展1年6地规范残留田间试验,3种有效成分及代谢物的最终残留量在青玉米、玉米、青玉米秸秆和玉米秸秆中均未检出。普通人群对3种有效成分的NEDI分别为0.035、0.032、0.28 mg/(kg bw),RQ分别为5.49%、1.29%和44.8%。膳食风险评估结果表明乙草胺、扑草净、2,4-滴异辛酯在春玉米中的残留量在可接受范围,不会对我国人体健康产生影响。

Joint effects of acetochlor and urea on germinating characteristics of crop seeds

In order to evaluate ecological risk of agrochemicals in common use, joint toxic effects of acetochlor and urea on germinating characteristics of Chinese cabbage (Brassica Pekinensis Rupr) seeds were investigated using the water-culture method and the soil-culture method. The results indicatedthat excessive application of acetochlor and urea, when the coninhibitory effects on the rate of seed germination, root elongation and hypocotyl length of Chinese cabbage. The inhibitory rate of the germinating characteristics of Chinese cabbage seeds was significantly increased with an increase in the concentration of acetochlor or urea. The two agrochemicals in water had a stronger toxicity than these in the soil at the same concentration.Among the three indexes, hypocotyl length was the most sensitive to the toxicity of acetochlor and urea.

不同除草剂及其组合对甘蓝田土壤养分及酶活性的影响

【目的】探明草甘膦、乙草胺及其组合剂对甘蓝田土壤养分及酶活性的影响,为其生产应用提供科学依据。【方法】采用田间试验方法,研究不同处理〔等量清水(CK)、草甘膦(T_(1))、乙草胺(T_(2))、草甘膦+乙草胺(T_(3))〕对甘蓝田土壤养分及酶活性的影响。【结果】不同处理有机质、全氮、有效氮、全磷、有效磷、全钾和有效钾分别为45.34~46.25 g/kg、2.43~2.54 g/kg、0.28~0.29 g/kg、0.69~0.71 g/kg、21.34~25.75 mg/kg、3.10~3.25 g/kg和0.10~0.14 g/kg,分别以T_(1)、T_(1)/CK、T_(3)、T_(2)/T_(3)、CK、T_(3)和CK最高,T_(2)、T_(2)、T_(1)/T_(2)/CK、T_(1)/CK、T_(1)、T_(1)和T_(1)最低,其中有机质、全氮、有效氮、全磷、有效磷和全钾各处理间差异不显著,有效钾CK显著高于T_(1)。过氧化氢酶、酸性磷酸酶、脲酶和蔗糖酶分别为2.84~2.92 mL/(g·24 h)、4.08~4.87μg/(g·24 h)、14.37~15.92 mg/(g·24 h)和8.00~9.43 mg/(g·24 h),分别以T_(3)、CK、CK和T_(1)最高,T_(1)、T_(2)、T_(1)和CK最低;过氧化氢酶T_(3)极显著高于T_(1),酸性磷酸酶、脲酶和蔗糖酶各处理间差异不显著。【结论】3个药剂处理对土壤有效磷和有效钾含量的影响较明显,对土壤有机质、全氮、有效氮、全磷和全钾影响相对不明显;生产上应避免高频使用除草剂单剂,应结合农业、物理和化学防治措施进行综合防控。

双刃剑乙草胺毒理学研究现状与挑战

本文综述了在农业中广泛使用的苗前除草剂乙草胺对环境和生态的影响。使用CiteSpace 5.7 R2软件对2012—2022年乙草胺毒性研究进行了全面的科学统计。乙草胺对非目标生物,包括土壤、植物、水生和陆地生物,甚至人类的有害影响已被广泛记录在案。对生物体的毒性作用归因于其通过疏水相互作用和氢键与抗氧化酶结合,导致过量的ROS积累和其它毒性途径的激活。这篇综述结合了现有的关于乙草胺环境影响的文献,确定了乙草胺在环境和可持续发展方面的挑战并提出了解决方案,为解决生态环境稳定问题提供了理论框架。