| Dissolved organic matter (DOM) adsorption on minerals plays an important role in many functions of soils, including the retention of carbon by soils. These interactions exist across scales in the environment, with implications from field to molecular levels. Work spanning these scales is presented, highlighting DOM dynamics in agricultural soils under different management as well as laboratory based studies of model biomolecule-mineral interactions. Field level studies show the amount and characteristics of DOM differ greatly between surface and subsoils. Observed depth trends in DOM are influenced by tillage, with tilled soils exhibiting two discreet distributions in DOM characteristics. A punctuated change from sorptive partitioning of surface DOM inputs to source driven DOM dynamics in subsoils is observed in tilled systems with no-till soils showing a gradual transition between the two. Molecular-level studies of protein (bovine serum albumin (BSA)) and nucleic acid (deoxyribonucleic acid (DNA)) interaction with the common soil minerals montmorillonite and goethite demonstrate the interplay between biomolecular characteristics and the kinetic, equilibrium and conformational aspects of adsorption. Furthermore, studies were conducted with both BSA and DNA in solution together. Under these conditions, assembly of BSA and DNA in solution is shown to impact the mechanism and quantity of biomolecule adsorption on goethite. These results enhance our understanding of organic matter interaction with soils at two distinct scales, both through probing DOM transformation in agricultural soils and mechanistic studies of biomolecule adsorption on minerals. |
