在含水飽和之系統中，土壤無機相被極性水分子所佔據，故系統中之有機污染物質以土壤有機質之兩相分佈作用為主，其吸附等溫線為線性；並以有機碳分佈常數Koc值，表示該特定的非離子有機污染物(NOCs)在土壤-水系統中流佈趨勢之指標值。然而近年來許多研究發現土壤有機質之結構、含量以及非離子有機污染物之物化特性等，對此常數造成影響。本研究針對於土壤有機質含量極低時，Koc值產生明顯變化之情形作為探討目標；利用鈉蒙特石作為吸附劑，將陽離子染料與界面活性劑作為吸附於土壤表面作為有機質唯一來源，並將所製備之低有機質土壤，進行污染物( BTEX與有機氯農藥)批次吸附實驗。 實驗結果顯示在低有機質土壤中，非離子有機污染物之Koc值確實高出一般土壤約4~10倍。當土壤被極少量有機質覆蓋時，無機相之極性作用力仍會透過有機相，而作用至到非離子有機污染物上，此現象較類似吸附作用，因此吸附等溫線之線性關係逐漸減弱，形成些許彎曲現象，又以BTEX極性較高的有機化合物受到土壤無機相極性作用最為明顯。 In the water-saturated soil system, the mineral phase of soil is occupied by the polar water molecules. The extent of soil uptake for contaminants is mainly controlled by partitioning to the soil organic matter and the sorption isotherms are all relatively linear. Normally, organic carbon normalized partition coefficient (Koc) is used to predict the distribution of NOCs (Nonionic Organic Compounds, NOCs) in the soil–water system. Our previous finding indicate that the quantity and the composition of soil organic matter would affect the organic carbon normalized partition coefficient (Koc). Therefore, the objective for our study is to elucidate the variation of Koc under the extremely low soil organic matter content. Na-montmorillonite was used as adsorbent. The cation dye and surfactant that adsorbed on the soil surface were the only source of the soil organic matter. Organochemical-clay complexes were prepared by reacting clay with organic cation. Adsorption isothems of NOCs (BTEX and organochlorine pesticides) were obtained by the batch experiment. The experimental results show that the Koc of the NOCs is significantly higher than natural soil about 4~10 times. When the soil was covered by only a few organic matter, the polar force of the soil mineral can penetrate organic matter film react on the NOCs. The predominant effect of SOM in this case is more like adsorption than partitioning. Moreover, all adsorption isotherms became a little crooked in this condition. Furthermore, BTEX which with higher polarity are profoundly affected by the polarity of soil mineral phase.
