Chemistry of organic matter in some New Zealand soils: correlation with pesticide sorption

摘要

Soil organic matter (SOM) regulates retention behaviour of pesticides in terrestrial environments. It is generally assumed that soils have same reactivity for pesticides per unit mass of organic C. However, the chemical composition of the organic constituents may differ among soils from various agroecological regions. Studies were performed to probe variations in the chemical composition of SOM using solid-state CPMAS ~(13)C NMR technique in a diverse range of New Zealand soils. Carbon chemistry of the soil samples revealed differences in the composition of organic matter in soils from different regions. Generally. N- and O-alkyls and acetals dominated in soils, while alkyl C was the second and aromatic C the third quantitatively most important C types seen by ~(13)C NMR. Overall, proportion of O-alkyl C in the soils varied from 23.3 to 59.5%, alkyl C from 18.4 to 46.6% and aromatic C ranged from 8.8 to 22.4%. Carbonyls were the least abundant group. Our recent studies on the role of the chemistryof SOM in retention propensities for pesticides in soils from various regions demonstrated markedly different sorption affinities for pesticides. Therefore dissimilarities in the chemical nature of SOM need to be considered while estimating sorption capacities of soils for xenobiotics.