REVIEW: Natural organic matter in aquatic systems – a South African perspective

Abstract

Natural organic matter (NOM) is a complex heterogeneous mixture of humic (HS) and non-humic substances which are widespread in the aquatic environment. Other constituents are amino acids, aliphatic and aromatic hydrocarbons containing oxygen, nitrogen and hydroxyl groups. It is the combination and proportions of these motifs which give NOM its overall polarity and reactivity. Its main origins include soils, residues of fauna and flora, microbial excrements and anthropogenic faecal loads, agriculture activities and urban landscapes. Due to the different origins of the precursor material and the extent of transformation it undergoes, the composition of NOM in different water bodies varies. Characterization methods for NOM can be divided into three broad categories namely: (i) direct measuring methods, which measure the amount of organic matter in the sample; (ii) spectrometric methods, which measure the amount of radiation absorbed and or released by chromophores; and (iii) fractionation methods, which separate NOM according to size and polarity.

Authors

Categories