[Research Progress on the Remediation Technology of Herbicide Contamination in Agricultural Soils].

Asthe most-used pesticides in the agricultural production process, herbicides are mainly applied to protect crops from weeds. However, with the increased global demand for food, the dosage of herbicides is rising annually, and the efficacy of herbicides is getting stronger, which can cause some environmental issues including the accumulation, migration and transformation, and toxic effects of herbicides in agricultural soils. According to the characteristics of herbicide contamination and regional agricultural production, developing green and low-carbon technologies to reduce the ecological risks of herbicides to the soil-crop systems is a current concern in the ecological environment field. In this paper, relevant studies in recent years on herbicide pollution management in agricultural soils were identified and reviewed, the research progress and application cases of remediation technologies for herbicide pollution was analyzed and demonstrated, and future research and development tendency regarding the remediation of herbicides pollution was also prospected. Current remediation technologies for herbicides mainly include bioremediation technologies (e.g., microbial remediation, enzyme remediation, and phytoremediation), adsorption, and immobilization technologies (e.g., biochar-based materials). The bioremediation technologieswere rather mature and had been applied to the herbicide-contaminated soil in fields. Additionally, many successful bioremediation cases have been reported. Moreover, in order to enhance the remediation effect on herbicide pollution in agriculture soils, remediation technologies have been gradually developed from a single model to a coupled model with physical,chemical, and biological technology, which can maximize the synergy of the multi-technology application.

[Growth and degradation characteristics of an efficient and broad-spectrum atrazine-degrading strain SB5]. / ä¸€æ ªé«˜æ•ˆå¹¿è°±èŽ åŽ»æ´¥é™è§£èŒSB5的生长和降解特性.

In this study, triazine-degrading strain SB5 was isolated and screened from the activated sludge contaminated with atrazine by enrichment culture technology. Based on its morphology and 16S rRNA gene analysis, strain SB5 was initially identified as Paenarthrobacter sp. It contained the atrazine-degrading genes trzN, atzB, and atzC. The addition of glucose, sucrose, sodium citrate, yeast extract and peptone to the culture medium significantly increased the biomass and atrazine degradation efficiency of strain SB5. The addition of (NH4)2SO4 and NH4Cl inhibited the biomass of strain SB5, but did not affect its degradation efficiency for atrazine. The addition of starch did not affect the biomass of strain SB5, but significantly inhibited its degradation for atrazine. Strain SB5 showed good atrazine tolerance and atrazine degradation ability in the temperature range of 4-42 ℃, initial pH of 4-10 and initial concentration of 50-1000 mg·L-1. Using 100 mg·L-1 atrazine as the sole carbon source, the strain SB5 degraded 100% of atrazine within 36 h under the optimal conditions of 37 ℃ and initial pH 8.0. The results of degradation spectrum analysis showed that strain SB5 had a good degradation effect on the six triazine herbicides (simazine, terbuthylazine, propazine, cyanazine, ametryn and prometryn) at an initial concentration of 100 mg·L-1, and the degradation rates were 86.4%, 92%, 98.6%, 95.6%, 100% and 99.2% after 48 h of incubation, respectively. The results demonstrated that SB5 was an efficient and broad-spectrum degradation strain. The strain SB5 further enriched the strain resources for atrazine biodegradation, and its high-efficient and broad-spectrum degradation characteristics for triazine herbicides showed a potential application value in the development of bioremediation technology for the pollution of triazine herbicides.

Discovery of novel PDE10 inhibitors by a robust homogeneous screening assay.

AIM: To develop a homogeneous assay for high-throughput screening (HTS) of inhibitors of phosphodiesterase 10 (PDE10). METHODS: Purified human PDE10 enzyme derived from E coli, [(3)H]-cAMP and yttrium silicate microbeads were used to develop an HTS assay based on the scintillation proximity assay (SPA) technology. This method was applied to a large-scale screening campaign against a diverse compound library and subsequent confirmation studies. Preliminary structure-activity relationship (SAR) studies were initiated through limited structural modifications of the hits. RESULTS: The IC50 value of the control compound (papaverine) assessed with the SPA approach was comparable and consistent with that reported in the literature. Signal to background (S/B) ratio and Z' factor of the assay system were evaluated to be 5.24 and 0.71, respectively. In an HTS campaign of 71 360 synthetic and natural compounds, 67 hits displayed reproducible PDE10 inhibition, of which, 8 were chosen as the scaffold for structural modifications and subsequent SAR analysis. CONCLUSION: The homogeneous PDE10 SPA assay is an efficient and robust tool to screen potential PDE10 inhibitors. Preliminary SAR studies suggest that potent PDE10 inhibitors could be identified and developed through this strategy.

[Effects of chlorimuron-ethyl and urea on soil microbial biomass carbon and nitrogen and soil inorganic nitrogen].

A microcosm experiment was conducted to study the effects of different concentration chlorimuron-ethyl (20, 200, and 2000 microg x kg(-1) soil) and its combination with urea (120 mg x kg(-1) soil) on the dynamic changes of soil microbial biomass carbon and nitrogen and soil nitrate nitrogen and ammonium nitrogen. Applying chlorimuron-ethyl alone decreased the soil microbial biomass carbon and nitrogen throughout the experiment period (60 days), and the decrement increased with increasing chlorimuron-ethyl concentration. Chlorimuron-ethyl had little effects on the soil ammonium nitrogen and nitrite nitrogen in the early period of the experiment, but increased the soil ammonium nitrogen in the mid-period (15 d) and the soil nitrate nitrogen in the late period (after 30 days) significantly. Both urea addition and its combination with chlorimuron-ethyl increased the soil microbial biomass carbon and nitrogen obviously in a short time, but the effect of combined addition of urea and chlorimuron-ethyl weakened then. Applying urea and its combination with chlorimuron-ethyl resulted in a lasting increase of soil nitrate nitrogen and ammonium nitrogen.