Causes of variation in diuron KOC for a diverse set of soils were investigated.
HF-treatment increased KOC for all but three soils, on average by a factor of 2.4.
This showed organic matter–mineral interactions reduced KOC of whole soils.
There was no significant correlation between KOC for the whole and HF-treated soils.
KOC of HF-treated soils increased with aryl C and decreased with O-alkyl C, alkyl C.
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