鱼藤酮在不同类型土壤中的降解

Study on the degradation of rotenone in various soils

利用高效液相色谱法(HPLC)研究鱼藤酮在不同类型土壤(稻田土、菜田土和果园土)中的降解,并探讨土壤微生物、土壤含水量、紫外光照和土壤理化性质等因子对鱼藤酮降解的影响。结果表明,鱼藤酮在不同类型土壤中的降解符合一级动力学方程。避光条件下,鱼藤酮在稻田土(pH=5.5)、菜田土(pH=5.64)和果园土(pH=4.78)中的降解速率常数分别为0.164 5、0.147 8和0.120 3;鱼藤酮在灭菌菜田土中的半衰期为10.51 d,而在未灭菌菜田土中的降解半衰期为4.76 d。避光条件下,鱼藤酮在烘干的土壤中稳定,其半衰期为15.16 d;土壤含水量为田间饱和含水量的60%时,鱼藤酮半衰期为4.03 d;厌氧条件下,鱼藤酮半衰期为3.51 d。紫外光照也是加速鱼藤酮降解的重要因素,未接受紫外照射的土壤中的鱼藤酮半衰期为67.28 h,接受照射时仅为10.51 h。研究表明,鱼藤酮在土壤中的降解受微生物、紫外光照及土壤含水量的影响较大;土壤pH值越小,鱼藤酮滞留时间越长;此外,土壤理化性质也是影响鱼藤酮在土壤中滞留性的重要因子。本研究为正确评估鱼藤酮的环境安全性提供了依据。

The authors in this paper are engaged in the study on the degradation of rotenone in the soil in different conditions by using HPLC as well as on the effects of such factors as microorganisma, water content, ultraviolet irradiation, as well as the physico-chemical properties of the soil, on the process of degradation. The results of our study have shown that the degradation of rotenone in soils can be described by the first-order kinetics equation. The rotenone＇ s degradation rate constant proves to be equal to 0. 164 5 for the paddyfield soil, and 0.147 8 for the kaleyard soil, whereas it is 0.120 3 for the orchard soil, with the pH being 5.5, 5.64, 4.78, respectively. The half-life of the degradation of rotenone turns to be 10.51 d in the sterilized soil and 4.76 d in the non-sterilized soil. In addition, rotenone turns stable in the low water-holding capacity soil and its half-life proves to be 15.16 d in the dried soll and 4.03 d in the soil which water content is 60% of the field saturation percentage. It is also found that the ultraviolet light can accelerate the degradation of rotenone in the soils. Thus, it can be concluded that the main factors effecting rotenone degradation were the content of water, the activity of soil microorganism, as well as the UV irradiation. Besides, the characteristic features of the soil also prove to be of great significance, when the lower the pH of soil, the more the residues of rotenone in the soil.