草萘胺在五种土壤及其胶体上的吸附行为

土壤胶体是土壤中颗粒最细小的部分,由于具有巨大的比表面积和较高的吸附容量,是环境中污染物的重要吸附剂,直接影响到污染物的归趋和生物有效性.本文采用批次吸附试验的方法,研究了农药草萘胺在黄棕壤等5种土壤及土壤胶体上的吸附行为.结果表明,草萘胺在供试土壤及胶体上的吸附均能很好地符合Freundlich方程;与本体土壤相比,...     

Structural and functional diversity of bacterial community in soil treated with the herbicide napropamide estimated by the DGGE,CLPP and r/K-strategy approaches

Napropamide is one of the most commonly used herbicide in agricultural practice and can exhibit toxic effect to soil microorganisms. Therefore, the main objective of this study was to examine the genetic and functional diversity of microbial communities in soil treated with napropamide at field rate (FR, 2.25 mg kg⁻¹ of soil) and 10 times the FR (10 × FR, 22.5 mg kg⁻¹ of soil) by the denaturing gradient gel electrophoresis (DGGE) and the community level physiological profile (CLPP) methods. In addition, the r/K-strategy approach was used to evaluate the effect of this herbicide on the community structure of the culturable soil bacteria. DGGE patterns revealed that napropamide affected the structure of microbial community; however, the richness (S) and genetic diversity (H) values indicated that the FR dosage of napropamide experienced non-significant changes. In turn, the 10 × FR dosage of herbicide caused significant changes in the S and H values of dominant soil bacteria. DGGE profiles suggest an evolution of bacteria capable of degrading napropamide among indigenous microflora. Analysis of the CLPPs indicated that the catabolic activity of microbial community expressed as AWCD (average well-color development) was temporary positively affected after napropamide application and resulted in an increase of the substrate richness (S_R) as well as functional biodiversity (H) values. Analysis of the bacterial growth strategy revealed that napropamide affected the r- or K-type bacterial classes (ecotypes). In treated-soil samples K-strategists dominated the population, as indicated by the decreased ecophysiological (EP) index. Napropamide significantly affected the physiological state of culturable bacteria and caused a reduction in the rate of colony formation as well as a prolonged time of growth rate. Obtained results indicate that application of napropamide may poses a potential risk for soil functioning.     

敌草胺对油菜抗氧化酶活性及相关基因表达的影响

除草剂药害严重影响油菜产量,研究筛选预防药害发生的生物标记物,结合植物生长调节剂的药害缓解机制,可有效解决油菜田敌草胺的药害问题。以盆栽油菜为材料,研究敌草胺处理后抗氧化酶活性及相关基因表达的变化规律,探究赤·吲乙·芸苔的药害缓解机制。结果显示过氧化物酶（POD）反应最灵敏,1.2 g/L 敌草胺处理12 h酶活达到最高值;2.4 g/L敌草胺能够显著诱导油菜GST基因较对照6.4倍的高表达。4.8 g/L和6.0 g/L敌草胺处理48 h,叶片内SOD、POD、CAT活性和相关基因表达量显著低于对照,氧化损伤严重。喷施0.1 mg/L赤·吲乙·芸苔,能激活低浓度（1.2 g/L、2.4 g/L）敌草胺胁迫的油菜抗氧化系统,解除药害影响。综上,敌草胺对油菜抗氧化酶活性和相关基因表达整体呈低浓度促进高浓度抑制,先升高后降低的趋势。2.4 g/L敌草胺接近油菜受害的临界浓度,POD可用于药害发生的早期预警。喷施0.1 mg/L 赤·吲乙·芸苔可较好的缓解敌草胺产生的轻度药害。     

除草剂萘丙酰草胺在4种药用植物根中的残留分析

采用气质联用(GC-MS-SCAN)仪器测定了使用无药害的萘丙酰草胺正常剂量2 kg(a.i.)/hm2条件下的桔梗、轮叶党参、当归、地黄根中丙酰草胺量.结果表明,4种药用植物干燥根中未能检测出萘丙酰草胺残留痕迹.     

草萘胺在黄泥土不同粒径微团聚体上的吸附行为

采用超声分散法提取了太湖地区黄泥土中不同粒径的团聚体颗粒,用批次吸附试验的方法研究了除草剂草萘胺在各团聚体颗粒组上的吸附特点。结果表明,不同粒径微团聚体的草萘胺吸附等温线均可用Freundlich方程定量描述,Kf值介于5.56~11.40之间,以粒径<0.002mm和2.00~0.25mm两个粒组吸附容量最大,粒径0.25~0.02mm和0.02~0.002mm两个粒组吸附容量较小。在各团聚体粒组中对土壤吸附草萘胺相对贡献率最大的是粒径<0.002mm粒组。由于颗粒细小的微团聚体更易于在土壤-水环境中迁移,因此,草萘胺在黄泥土上的这种分布特点对环境的潜在影响不容忽视。