土壤中嗪草酮迁移和降解的研究

 通过两季马铃薯大田试验，研究了嗪草酮在灌溉沙壤土中的消失和移动情况。结果表明，表层土壤中，嗪草酮施用后最初7～15天内其含量急剧降低，此后随时间推移降低幅度平缓，1993年和1994年试验结束时的残留量分别为5.9μg/kg和2.3μg/kg。两年共采集的379个土样（分布在15～75cm各土层）中只有5个检测到有嗪草酮。1994年大田135cm土层处的水样中，嗪草酮的检测率高达66％，检测浓度范围为0.06～15.85μg/kg，平均浓度为1.94μg/kg。相比较，嗪草酮在大田试验中的消失速率远大于实验室控制条件下的降解速率。     

Kinetic,equilibrium and thermodynamic studies for the sorption of metribuzin from aqueous solution using banana peels,an agro-based biomass

Banana peels were employed for the removal of metribuzin from aqueous solution. Sorption in the batch mode was optimized regarding pH, contact time, sorbent dose, initial pesticide concentrations, and temperature. The sorption data were fitted to pseudo-first-order, pseudo-second-order, intraparticle diffusion, Elovich, and liquid film diffusion model, the pseudo-second-order exhibiting best fit (R² = 0.9803). Of the four most common sorption isotherm models (Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich), the data followed the Langmuir isotherm with highest correlation. The maximum adsorption capacity was found to be 167 mg g^?1. Gibbs free energy, enthalpy, and entropy showed that the sorption was exothermic and spontaneous.     

嗪草酮降解菌Rhodococcus sp.MA的降解特性及固定化应用

从农田土壤中分离得到1株嗪草酮高效降解菌株,命名为MA,该菌5 d对50 mg·L^-1嗪草酮的降解率达到74.8%,最适反应温度和pH分别为30℃和7.0.根据表型与生理生化特征及16S rRNA序列分析,将其鉴定为Rhodococcus sp.MA.利用气相色谱-质谱联用（GC-MS）鉴定菌株MA降解嗪草酮的中间产物为脱氨基嗪草酮.以海藻酸钠为包埋剂,经正交试验表明,3%海藻酸钠、2% CaCl₂、包埋比8：1和固定时间6 h条件下,菌株对嗪草酮的降解效率最高,为71.2%.将固定化菌体细胞用于修复实验,结果表明,未固定化处理的菌液对湖水及池塘水中嗪草酮（15 mg·L^-1）的去除率分别为72.1%和69.9%;固定化处理后可提高对嗪草酮的去除率,分别达到87.3%和82.6%,具有良好的应用前景.     

降解嗪草酮微生物菌剂的制备及稳定性研究

通过富集培养分离出嗪草酮降解菌N1,降解菌在固体平板上培养,菌落大,表面粗糙,扁平,不规则,为质地软、稍有光泽的白色菌落,直径为5～7mm.菌体细胞为杆状,末端方,成短或长链,菌体大小为1.0～ 1.2 μm× 3.0～ 5.0 μm.将N1降解菌制成菌剂,用气楣色谱法进行定量分析,通过单因素试验确定菌剂中载体配比、接种菌液量、加入营养液量、发酵时间、烘干温度等影响因子的优势条件,设计正交试验确定最优菌剂制备条件:m(豆粕):m(麦麸):m(木屑):m(硅藻土)比例为60:20:15:5,接种菌液量为15％,营养液量为10％,发酵时间为48 h,烘干温度为30℃.在上述条件制备的菌剂对嗪草酮的降解率为79％.该菌剂在25℃下保存50d后对嗪草酮仍有较高的降解效果.     

嗪草酮农药生产环合废水物化处理工艺研究

采用絮凝-树脂吸附组合工艺对嗪草酮农药生产环合废水进行物化预处理.实验确定的最佳工艺条件为:(1)絮凝-絮凝剂为10%硫酸铝溶液(W/W),投加量为8%(V/V),废水pH为6～9,快速搅拌1 min(150～180 r/min),慢速搅拌15 min(80～100 r/min);(2)树脂吸附-双柱串联吸附:上柱液p...     

Kinetics of metribuzin release from bentonite-polymer composites in water

A series of bentonite polymer-composites (BPCs) loaded with metribuzin were studied for their controlled release in aqueous medium. The release of active ingredient from BPCs was significantly lower as compared to commercial metribuzin formulation. The results revealed that the cumulative metribuzin release was highest (81%) from the BPCs containing 8% clay (commercial bentonite) and 2% metribuzin which correspond to the lowest (14 days) half-life values i.e., time required for 50% release of active ingredient (t_1/2). The metribuzin release from the BPCs decreased with increased concentration of clays in polymer matrix and the release was further decreased with BPCs prepared with pure nano-bentonite. BPCs containing 12% clay and 2% metribuzin showed maximum t_1/2 values i.e., 25 and 51 days for commercial bentonite and pure nano-bentonite as clay sources, respectively. The differential behaviour in the metribuzin release rates from BPCs was ascribed due to variations in crosslinking of metribuzin in the composites. As metribuzin release was found to be slower in BPCs compared to commercial formulation, it could be used for control of weeds tailored to different crops.     

Phytotoxicity and persistence of metribuzin residues in black soil

A bioassay procedure based on the root and shoot growth of cucumber and sorghum were used to study the phytotoxicity, as affected by varying the concentration of metribuzin, and persistence of metribuzin residues in soil. Sorghum and cucumber were found to be very susceptible test plant species to metribuzin. It was found that the persistence and phytotoxicity increased with increasing rate of application of metribuzin, and the relationship between herbicide concentration and phytotoxicity was best described by a quadratic equation. Sorghum and cucumber plants emerged as very sensitive new bioassay plants for metribuzin and could detect residues even at 0.010 and 0.046?ppm in the post harvest soil of potato crop.     

Constructing herbicide metribuzin sustained-release formulations based on the natural polymer poly-3-hydroxybutyrate as a degradable matrix

Polymer poly(3-hydroxybutyrate) [P(3HB)] has been used as a matrix in slow-release formulations of the herbicide metribuzin (MET). Physical P(3HB)/MET mixtures in the form of solutions, powders, and emulsions were used to construct different metribuzin formulations (films, granules, pellets, and microparticles). SEM, X-Ray, and DSC proved the stability of these formulations incubated in sterile water in vitro for long periods of time (up to 49 days). Metribuzin release from the polymer matrix has been also studied. By varying the shape of formulations (microparticles, granules, films, and pellets), we were able to control the release time of metribuzin, increasing or decreasing it.     

Controlled release formulations of metribuzin: Release kinetics in water and soil

Controlled release (CR) formulations of metribuzin in Polyvinyl chloride [(PVC) (emulsion)], carboxy methyl cellulose (CMC), and carboxy methyl cellulose-kaolinite composite (CMC-KAO), are reported. Kinetics of its release in water and soil was studied in comparison with the commercial formulation (75 DF). Metribuzin from the commercial formulation became non-detectable after 35 days whereas it attained maxima between 35–49 days and became non-detectable after 63 days in the developed products. Amongst the CR formulations, the release in both water and soil was the fastest in CMC and slowest in PVC. The CMC-KAO composite reduced the rate of release as compared to CMC alone. The diffusion exponent (n value) of metribuzin in water and soil ranged from 0.515 to 0.745 and 0.662 to 1.296, respectively in the various formulations. The release was diffusion controlled with half release time (t_1/2) from different controlled release matrices of 12.98 to 47.63 days in water and 16.90 to 51.79 days in soil. It was 3.25 and 4.66 days, respectively in the commercial formulation. The period of optimum availability of metribuzin in water and soil from controlled released formulations ranged from 15.09 to 31.68 and 17.99 to 34.72 days as against 5.03 and 8.80 days in the commercial formulation.