Adsorption of Herbicide Diuron in Pineapple-Growing Soils of Eastern Thailand

摘要

Four pineapple-growing soils (topsoil) were collected from Chonburi and Chachoengsao provinces in Thailand to analyze the physiochemical properties, chemical composition of organic carbon and diuron adsorption isotherm (batch experiment). Results revealed that diuron adsorption rate of soils was low (ranging between 1.81 and 27.63%) and adsorption data fit well with Freundlich equation (R-2 = 0.83-0.97), in which the adsorption coefficient (K-F) is between 0.57 and 4.87 L kg(-1). Soil organic matter and clay content were responsible for the adsorption of diuron in these soils (r = 0.95** and 0.78**, respectively). In addition, total nitrogen, silt content and cation exchange capacity also had a positive correlation with diuron adsorption in the soils. Organic carbon partitioning coefficient (K-OC) of soils ranged from 125.84 to 480.36 L kg(-1) and showed a positive correlation with the functional group of organic carbon, including aromatic carbon and carbonyl (r = 0.80** and 0.67*, respectively). This low rate of diuron adsorption in pineapple-growing soils posed a risk in diuron contamination in the environment. The increase of organic matter in these soils, particularly those coarse to medium-textured soils, through proper soil management would increase the herbicide adsorption ability of these soils and should subsequently reduce the contamination markedly.