根际效应对狼尾草降解土壤中阿特拉津的强化作用

采用盆栽根袋培养法,研究了根际效应在狼尾草降解土壤阿特拉津中的作用。结果表明,盆栽培养28 d后,狼尾草对土壤中阿特拉津有较好的根际强化降解效果,狼尾草根际土壤阿特拉津去除率为52.70%,非根际土壤的阿特拉津去除率为37.60%。土壤自身具有修复阿特拉津的潜能,无狼尾草处理的湛江砖红壤中阿特拉津降解以非生物降解为主,降解率为16.90%,土著微生物对阿特拉津的生物降解效果弱于非生物降解,仅为11.70%。狼尾草通过根际效应显著提高了土壤总微生物数量和活性,增加了土壤可培养细菌、真菌和放线菌的数量,尤其是土壤可培养细菌数量,提升了土壤细菌群落结构的丰富度和均匀度,进而间接强化土壤阿特拉津的生物降解。     

氰津·莠30%悬浮剂的气相色谱分析

本文采用气相色谱法,使用CP7906X;英毛细管柱和FID检测器,对混剂中的氰草津和莠去津进行分离与定量。邻苯二甲酸二正丁酯为内标物。分析结果表明氰草津和莠去津的线性相关系数分别为0．99995、0．99999;标准偏差分别为0．23、0．16：变异系数分别为1．49％、1．06％;回收率分别在98．94～100．11％和98．38～101．51％之间。     

不同浓度莠去津对谷子田间杂草的防除效果(英文)

该研究比较了不同浓度莠去津(播后苗前喷药处理)对谷子田间杂草的防除效果,为筛选适宜谷子生产的除草剂最佳使用浓度提供理论依据。结果表明:喷施25 d和40 d后,莠去津4 500 ml/hm_2处理株防效和鲜重防效最好,鲜重防效达到83.16%和86.43%,与喷施清水(CK)相比2 250 ml/hm处理增产效果最佳,增产率达到54.31%,3 000 ml/hm_2次之,因此2 250 ml/hm_2是谷子生产中莠去津(播后苗前喷药)使用的最佳浓度。     

污泥土地利用途径分析

污泥中含有丰富的氮、磷和有机质等肥力成分,土地利用是污泥处置的主要途径。污泥和污泥堆肥的土地施用可以促进植物的生长、提高作物的产量以及明显改善土壤的物理和生物学性质,然而污泥中的重金属元素是限制其大规模农田利用的重要因素。污泥和施污土壤中重金属形态的研究可以用来评价土壤中重金属的生物有效性以及它们在土壤中的移动性。文章概述了提取土壤中重金属元素的主要方法及污泥土地利用的方式。     

Persistence of herbicides in forest nursery soils

The persistence of the four herbicides atrazine, hexazinone, lenacil and linuron was studied in forest nursery soils. The adsorption capacities of the soils for the chemicals were described by the distribution coefficients kj and k_oc. Due to the low content of organic matter in the soils the k_a‐values were low, in several cases being <1 for hexazinone. Hexazinone also had the lowest k _oc‐value (30) while the other substances had k_oc ‐values within the range 200–400. In some cases hexazinone showed great mobility under field conditions. The formula c=c_o‐kt^1/2 was used to describe the disappearance of the herbicides from the various soils. The rate of degradation of the four herbicides correlated well with the rate of respiration in the same soils in laboratory experiments, and for linuron reasonably well also in field experiments. In the field experiments the herbicides penetrated the top soil layer. In the subsoil the risk of further transport downward to the drainage system or ground water increased, especially for hexazinone. Linuron as well as the fungicides maneb and tolylfluanid suppressed the decomposition rate of hexazinone in laboratory experiments.     

粘土矿物固定化微生物对土壤中阿特拉津的降解研究

以粘土矿物为载体,采用吸附挂膜法对已筛选的阿特拉津降解菌株进行固定化,并应用固定化微生物降解土壤中的阿特拉津。结果表明,该菌株在粘土矿物上生长良好,根据菌种生理生化特性、环境扫描电镜图片以及16S rDNA基因的相似性分析初步鉴定该菌株为Ochrobactrum sp.。接种降解菌能明显加快阿特拉津在土壤中的降解速率,粘土矿物固定化微生物的降解效果要明显优于游离菌,粘土矿物粒径越小,固定化微生物的降解效果越好,纳米粘土矿物固定化微生物的降解效果要好于原粘土矿物。用一级动力学方程描述阿特拉津在土壤中的降解过程,不同土壤中阿特拉津的降解速率不同。阿特拉津在红壤、砂姜黑土、黄褐土中的降解半衰期（t1/2）分别为36.9、49.1、55.0 d,投加纳米蒙脱石固定化降解菌后的半衰期则分别为16.3、25.3、21.7 d。     

硝磺草酮·莠去津550克，升悬浮剂防除夏玉米田杂草田间药效试验

通过硝磺草酮·莠去津550克／升悬浮剂在夏玉米苗2、4、6叶期对田间杂草进行防效试验,结果表明：其对夏玉米田间禾本科杂草和阔叶杂草具有较好的防除效果,且对夏玉米生长安全。在60～120mL／667m。剂量下,药后30d,对禾本科杂草和阔叶杂草的株防效分别为76．1％～100．0％,95．5％～100．0％,鲜重防效为82．6％～100．0％,且2、4叶期施药,对夏玉米产量增产8．4％～27．5％。     

52%烟嘧磺隆·莠去津可湿性粉剂防除夏玉米田杂草药效试验

2009年对52%烟嘧磺隆·莠去津可湿性粉剂防除夏玉米田杂草进行了田间药效试验。结果表明,666.7m2用52%烟嘧磺隆.莠去津可湿性粉剂75~100 g,茎叶处理20 d对一年生禾本科、阔叶杂草的株防效可达89.3%~95.2%,40 d鲜重防效达90.6%~96.3%,增产9.43%~16.23%,且对玉米安全。     

Satellite images as a tool to identify accelerated atrazine mineralization in soils

Microflora adaptation to atrazine (6-chloro-N²-ethyl-N⁴-isopropyl-1,3,5-triazine-2,4-diamine) mineralization due to its frequent use on the same soil has been clearly demonstrated. Studies show accelerated herbicide mineralization with mineralization percentages reaching up to 60% of the applied atrazine in a few days, which results in decreased weed control efficiency. Frequently, atrazine doses are increased to circumvent low efficiency, although this solution does not solve accelerated atrazine mineralization. The identification of soils with accelerated atrazine mineralization to guide selection of adequate management strategies and achieve good atrazine performance in adapted soils is critical. The present research assessed accelerated atrazine mineralization recognition on the basis of previous years maize (Zea mays L.) cropping as an indicator of atrazine use identified using satellite images. Three years of crop sequences were monitored by visual interpretation of Landsat satellite images. Bands 3, 4, and 5 were evaluated and corresponded, respectively, to red, near infrared, and mid-infrared. Vegetation was distinguished by selecting the R:4 G:5 B:3 color composition. Prior to assessment, atrazine behavior was evaluated in soils with high (S_H) and low (S_L) atrazine mineralization capacity. ¹⁴C-ring-labeled atrazine distribution between extractable, non-extractable, and mineralized soil culture fractions was subject to monitoring. Atrazine mineralization was determined by soil laboratory incubation. These included some soils of known past use and others with history predicted by satellite imagery. Topsoil (0-10 cm) samples were extracted according to two soil sampling strategies: Type A sampling (designated site A) consisted of 25 topsoil samples with known history, and type B sampling (designated site B) comprised 20 topsoil samples from history inferred via satellite imagery.Atrazine mineralization was monitored for 23 days under laboratory conditions. Soil ¹⁴C applied mineralization ranged from 0.3-73.0% and 0.2-30.0% in sites A and B, respectively. These broad ranges were closely related to maize presence/absence in the crop rotation at both sites. Following three straight growing seasons of maize, atrazine mineralization capacity reached a plateau in site A soils, with similar results observed in site B soils. This pattern suggests that satellite image information will be of utility to soil managers in selecting strategies to improve atrazine efficiency, including simultaneous fertilization, post-emergence atrazine applications, and choice of maize hybrids based on canopy architecture and weed competitiveness.     

Inlfuence of Soil pH and Temperature on Atrazine Bioremediation

Present study was conducted to clarify soil pH and temperature influence on different atrazine bioremediation techniques. For this purpose, sodium citrate,Arthrobactorsp. strain DNS10, sawdust and animal manure were selected to clarify their atrazine remediation efficiency under pH 5, 7 and 9 and temperatures 20, 30 and 40℃, respectively. Results showed that atrazine remediation was generally optimized at pH 7 and 30℃ for all the treatments except sodium citrate as soil treated with sawdust was not temperature dependant, but at pH 5 remediation process was determined slower. Atrazine remediation in soil with no additional amendment was only 34%, while in soil treated with sawdust, DNS10, sodium citrate and animal manure were 75.17%, 89%, 74.17% and 76.83% at optimized pH and temperature. Overall atazine removal rate was significantly (≥0.01) higher with increasing in temperature at all the selected pH.