关键词: 甲氧基丙烯酸酯类杀菌剂, 土壤, 降解, 吸附, 地下水

Abstract:

Adsorption and degradation of two kinds of strobilurin fungicides in red soil from Jiangxi, black soil from Northeast China and paddy soil from the Taihu region were systematically studied through an in-lab simulation experiment, and their impacts on groundwater analyzed with GUS index. Results show that the two fungicides vary quite sharply in degradation rates, because they have different functional groups. Under room temperature and aerobic conditions, Picoxystrobin is fairly hard to degrade in the red soil and black soil, and hard to degrade pesticides in the paddy soil, while trifloxystrobin degrades easily in all the 3 types of soils. But under room temperature and anaerobic waterlogging conditions, picoxystrobin is moderate in degradability, while trifloxystrobin is high in all the three types of soils. Obviously, anaerobic waterlogging conditions facilitate degradation of the pesticides and anaerobia is an important factor affecting the degradation of strobilurin fungicides. Picoxystrobin is well adsorbed in the 3 types of soils, which fits the Freundlich equation well, with K_oc being 811, 613 and 926 in the red soil, black soil and paddy soil, respectively, indicating that the soils are quite low in adsorption capability. Content of organic matter in the soil is the major factor affecting the soil's capacity of adsorbing picoxystrobin. HPLC reveals that trifloxystrobin is higher than 20 000 in K_oc indicating that trifloxystrobin belongs to the category of chemicals easily adsorbed. In all the three types of soils picoxystrobin varies between 1.8 and 2.8 in GUS index, indicating that the pesticide is leachable and poses a potential risk of polluting the groundwater, while trifloxystrobin is lower than 1.8 in GUS index, indicating that the chemical poses little pollution risk to the groundwater.

Key words: strobilurin fungicides, soil, degradation, adsorption, groundwater