Detection of herbicides in water bodies of the Samambaia River sub-basin in the Federal District and eastern Goiás

Abstract

The objective of this study was to identify and quantify herbicide residues in water samples of rain, cisterns, streams, ponds, springs, semi-artesian wells, dams and a river in the Rio Samambaia sub-basin in the Federal District and eastern Goiás. A total of 287 samples were collected from 20 farms in the sub-basin in the rainy (February, summer) and dry (August, winter) seasons in 2016. Aminomethylphosphonic acid (AMPA, a glyphosate metabolite), clethodim, chlorimuron-ethyl, diuron, fluazifop acid (a fluazifop-p-butyl metabolite and the active ingredient), haloxyfop acid (a haloxyfop-methyl metabolite and the active ingredient), imazamox, mesotrione, metsulfuron, nicosulfuron and pendimethalin were not identified in any water sample. In the rainy season, approximately 99% of the samples contained residues at least one of the evaluated herbicides; in the dry season (, 100% of the samples contained residues of at least one of the evaluated herbicides. When considering only detection frequency, metribuzin, atrazine, clomazone and haloxyfop-methyl were the main herbicides found in the water of the Samambaia River sub-basin. In turn, based on levels higher than the limit of quantification, the main compounds detected were atrazine, clomazone, haloxyfop-methyl and glyphosate. In both seasons, the highest relative concentrations of herbicides for the rainy and dry seasons were found in spring water, 25% and 56%, respectively, and dam water, 23% and 16%, respectively.     

含莠去津和乙草胺河水灌溉对苗期水稻危害的研究

本文以１９８８、１９９２和１９９３年洋河流域张家口市部分水稻田污染受害事故为背景，通过事故现场调查资料分析、洋河水质监测、宣化区污染源调查、水稻的药害暴露实验和模型计算，研究了含有除草剂莠去津和乙草胺的河水灌溉对苗期水稻的危害。结果显示，河水中莠去津和乙草胺对水稻苗期的安全灌溉浓度分别为０．０１ｍｇ／Ｌ和０．０５ｍｇ／Ｌ；河水中莠去津对水稻的致死浓度是０．１ｍｇ／Ｌ；ｐＨ、ＮＨ３－Ｎ和表面活性剂对这种危害作用具有一定的协同效应；为了满足河水对水稻的灌溉水质要求，污染源允许排放的莠去津和乙草胺分别为１．０ｋｇ／ｄ和２．０ｋｇ／ｄ。     

除草剂阿特拉津(Atrazine)的环境行为综述

阿特拉津（２－氯－４－乙胺基－６－异丙氨基－１，３，５，－三氮苯）是目前应用广泛的化学除草剂之一。在世界许多国家和地区的地表水和地下水中已检出了阿特拉津的残留物。阿特拉津对人类的威胁究竟有多大，已成为目前研究的热点。本文从阿特拉津的检测方法、动力学性质、生化性质及风险评估四个方面进行了综述，并提出了自己的观点。     

Impact of a native Streptomyces flavovirens from mushroom compost on green mold control and yield of Agaricus bisporus

ABSTRACT

Thirty-five actinobacterial isolates, obtained from button mushroom (Agaricus bisporus) substrates (i.e., compost in different phases of composting, black peat or casing layer) in Serbia in 2014–2016 were tested in vitro against the causal agents of green mold in cultivated mushroom. Out of six most promising isolates, A06 induced 42.4% in vitro growth inhibition of Trichoderma harzianum T54, and 27.6% inhibition of T. aggressivum f. europaeum T77. The novel strain A06 was identified as Streptomyces flavovirens based on macroscopic and cultural characteristics and 16S rDNA sequence and used in mushroom growing room experiments. Actinobacteria had no negative influence on mycelial growth of the cultivated mushroom in compost in situ. Isolate S. flavovirens A06 enhanced mushroom yield significantly, up to 31.5%. The A06 isolate was more efficient in enhancing yield after inoculation with the compost mold T. aggressivum (26.1%), compared to casing mold T. harzianum (8%). Considering disease incidence, actinobacteria significantly prevented green mold in compost caused by T. aggressivum (6.8%). However, fungicide prochloraz-Mn had a more significant role in reducing symptoms of casing mold, T. harzianum, in comparison with actinobacteria (24.2 and 11.8%, respectively). No significant differences between efficacies of S. flavovirens A06 and the fungicide prochloraz-Mn against T. aggressivum were revealed. These results imply that S. flavovirens A06 can be used to increase mushroom yield and contribute to disease control against the aggressive compost green mold disease caused by Trichoderma aggressivum.     

典型土壤组分及其与丁草胺除草剂作用的红外光谱研究

运用红外光谱法对3种典型土壤(红壤、潮土和黑土)的矿物质、胡敏酸及其与丁草胺的吸附附着物进行了研究.结果表明,江西红壤为高岭石型矿物质,在3 703,3 628,1 089,1 035,914,696及471 cm-1处有特征吸收峰.北京潮土和黑龙江黑土为蒙脱土型矿物质,在1 432和872 cm-1处有特征吸收峰,而在3 703和3 628 cm-1处吸收较弱或微弱.不同土壤中胡敏酸的组成基本相同,均在3 420,2 935,2 847,1 724,1 660及1 035 cm-1处有明显吸收,表明其含有缔合羟基、芳烃、羰基、醇、酚及酸等.丁草胺与土壤胡敏酸的吸附机理主要是在胡敏酸的羰基及酚醇羟基上形成氢键.      

Effect of imazaquin applications on the growth,leaf chlorophyll and yield of soybean in the Guinea Savanna of Nigeria

Abstract

Field trials were conducted during the wet seasons of 1989, 1991, 1994 and 1995 to evaluate the effects of pre‐emergence and post‐emergence applications of four rates of imazaquin (0.00; 0.15; 0.30 and 0.45kg a.i/ha) on the growth, leaf chlorophyll types and grain yield of soybean c.v. SAMSOY 2. Imazaquin applications had no significant effect on the growth of soybean roots on most of the sampling dates, but pre‐and post‐emergence applications of imazaquin at 0.30 and 0.45kg a.i/ha reduced soybean root nodules at 5 and 7 weeks after planting (WAP). Soybean shoot growth was generally reduced at 5WAP by the pre‐emergence and at 7WAP by the higher rates (0.30 & 0.45kg a.i/ha) of post‐emergence application of imazaquin. Pre‐and post‐emergence applications of imazaquin showed a strong tendency to reduce the concentration of chlorophyll a and total chlorophyll at at 3 and 5WAP respectively. The concentrations of chlorophyll types in soybean leaves at 9WAP was generally comparable among most treatments especially in 1991. Whole plant fresh weight of soybean at 7WAP was reduced by all rates of post‐emergence application of imazaquin. However, there was no significant difference in the whole plant dry weight of soybean at 3 to 7 WAP in 1989 and at 3, 5 and 9WAP in 1991. In each trial, pre‐and post‐emergence applications of soybean significantly increased the grain yield of soybean compared with the control treatment. This study showed that, inhibition of soybean shoot growth and leaf chlorophyll concentration was transient and that soybean plants require about 6 weeks for complete recovery from imazaquin phytotoxicity.     

Biodegradation of triazine herbicide metribuzin by the strain Bacillus sp. N1

By enrichment culturing of soil contaminated with metribuzin, a highly efficient metribuzin degrading bacterium, Bacillus sp. N1, was isolated. This strain grows using metribuzin at 5.0% (v/v) as the sole nitrogen source in a liquid medium. Optimal metribuzin degradation occurred at a temperature of 30ºC and at pH 7.0. With an initial concentration of 20 mg L^?1, the degradation rate was 73.5% in 120 h. If the initial concentrations were higher than 50 mg L^?1, the biodegradation rates decreased as the metribuzin concentrations increased. When the concentration was 100 mg L^?1, the degradation rate was only 45%. Degradation followed the pesticide degradation kinetic equation at initial concentrations between 5 mg L^?1 and 50 mg L^?1. When the metribuzin contaminated soil was mixed with strain N1 (with the concentration of metribuzin being 20 mg L^?1 and the inoculation rate of 10¹¹ g^?1 dry soil), the degradation rate of the metribuzin was 66.4% in 30 days, while the degradation rate of metribuzin was only 19.4% in the control soil without the strain N1. These results indicate that the strain N1 can significantly increase the degradation rate of metribuzin in contaminated soil.     

Polynomial response of 2,4-D mineralization to temperature in soils at varying soil moisture contents,slope positions and depths

The herbicide 2,4-D [2,4-(dichlorophenoxy) acetic acid] is a widely used broadleaf control agent in cereal production systems. Although 2,4-D soil-residual activity (half-lives) are typicaly less than 10 days, this herbicide also has as a short-term leaching potential due to its relatively weak retention by soil constituents. Herbicide residual effects and leaching are influenced by environmental variables such as soil moisture and temperature. The objective of this study was to determine impacts of these environmental variables on the magnitude and extent of 2,4-D mineralization in a cultivated undulating Manitoba prairie landscape. Microcosm incubation experiments were utilized to assess 2,4-D half-lives and total mineralization using a 4 × 4 × 3 × 2 factorial design (with soil temperature at 4 levels: 5, 10, 20 and 40°C; soil moisture at 4 levels: 60, 85, 110, 135 % of field capacity; slope position at 3 levels: upper-, mid- and lower-slopes; and soil depth at 2 levels: 0–5 cm and 5–15 cm). Half-lives (t_1/2) varied from 3 days to 51 days with the total 2,4-D mineralization (M _T ) ranging from 5.8 to 50.9 %. The four-way interaction (temperature × moisture × slope × depth) significantly (p< 0.001) influenced both t_1/2 and M _T. Second-order polynomial equations best described the relations of temperature with t_1/2 and M_T as was expected from a biological system. However, the interaction and variability of t_1/2 and M_T among different temperatures, soil moistures, slope positions, and soil depth combinations indicates that the complex nature of these interacting factors should be considered when applying 2,4-D in agricultural fields and in utilizing these parameters in pesticide fate models.     

除草剂对土壤氮素循环的影响

土壤微生物参与土壤氮素循环的生物学与生物化学过程,对氮素形态转化与去向产生很大影响。在现代农作物生产上农田普遍施用除草剂,除草剂进入土壤生态环境中影响土壤微生物种群数量、活性和土壤氮素循环过程,在一定程度上改变氮素各去向的比例。因此,除草剂的施用对植物氮素吸收利用和土壤氮的环境释放具有一定效应。文章综述了除草剂对生物固氮、土壤氮矿化与转化、氨挥发、硝化反硝化、温室气体N2O排放、植物的氮吸收利用、土壤氮损失等方面的影响,并提出了今后进一步研究的方向,为减少氮素损失和温室气体排放以及除草剂使用的安全性评价提供参考。     

基于三维灰色关联度方法的大型煤炭企业转型能力评价研究

在中国转变经济发展方式的背景下,结合大型煤炭企业的转型任务与目标,对其转型能力结构进行分析,构建了主客观指标相结合的转型能力评价指标体系.采用三维灰色关联度方法,基于21家上市煤炭企业面板数据进行评价,发现大型煤炭企业转型能力不断提高,但整体水平欠佳,尤其是转型战略规划能力亟需提高,因此必须加强高管团队建设与学习,根据转型战略积极进行包括人才资源在内的资源储备,大力进行技术创新与管理创新.