제주도 토양에서 Diazinon, Fenitrothion, Alachlor, Metalaxyl 및 Atrazine의 흡착 및 용탈특성

Abstract

The agricultural soils around the springwaters being heavily affected by pesticide run-off and the agricultural soils around wells considering the regional characteristics were sampled at 24 stations among the soils of Jeju Island which have the diverse physicochemical properties, their physicochemical properties were examined. In these soils, the adsorption and leaching characteristics of diazinon, fenitrothion, alachlor, atrazine and metalaxyl were investigated. The results obtained in this study were summarized as follows:

1. Examining the major physicochemical properties of soils affecting the adsorption and leaching of pesticides, the values of soil pH, organic matter content and cation exchange capacity (CEC) were in the range of 4.64～8.30, 0.9∼13.1% and 12.7～31.7 meq/100 g, respectively, indicating their values were different greatly depending on the sampling stations. The contents of clay, silt and sand in soil texture were 9.4～42.7%(mean 21.2%), 9.8～58.1%(mean 22.6%) and 19.7～76.4%(mean 56.2%), respectively, showing the great difference in each content depending the sampling stations, and sampled soils were classified as 7 clay loam, 4 light clay, 4 sandy clay loam, 4 sandy loam, 2 silty clay, 2 loam and 1 sandy clay in the classification of soil texture.

2. The Freundlich constant, KF, which gives a measure of the adsorption capacity, decreased in the order of fenitrothion > diazinon > simazine > alachlor > atrazine > metalaxyl among the pesticides. Among the soils, it was very highly correlated with organic matter content (r2 = 0.800～0.876) and CEC (r2 = 0.715～0.825), highly correlated with clay content (r2 = 0.473～0.575), soil pH (r2 = 0.40～0.45), negatively correlated with sand content (r2 =-0.299～-0.337) and little correlated with silt content.

3. The Freundlich constant, 1/n, which gives a measure of the adsorption intensity, was in the range of 0.5～0.9 for fenitrothion, alachlor and metalaxyl and in the range of 0.9～1.1 for diazinon in most soils, indicating that the adsorption kinetics correponded to the L type for the former and C type for the latter in the clasification of proposed by Giles et al. (1960).

4. The leaching of pesticides in soil column showed the reverse relationhip with their adsorption in soils, namely, the pesticides were leached the most quickly for the soils with the lowest organic matter content, CEC and clay content among the soils, and were leached in the order of metalaxyl > atrazine > alachlor > diazinon > fenitrothion among the pesticides,

5. With the results of evaluation of groundwater contamination potential of pesticides using groundwater ubiquity score (GUS) proposed by Gustafson(1989), the leaching potential of pesticides was in the order of metalaxyl > atrazine > alachlor > diazinon > fenitrothion based on high GUS value. The pesticides exceeding GUS 2.8 and with moderately leaching potential and with little leaching potential in most soils were metalaxyl, atrazine, and alachlor, diazinon and fenitrothion, respectively.