Soil organic matter and biogenic-abiogenic interactions in soils of Larsemann Hills and Bunger Hills, East Antarctica

Abstract

Although Antarctic soils are usually described as weakly developed, recent studies indicated the significant variability in soil forming conditions across the sixth continent as well as considerable diversity of soils. The identification of pedogenetic processes in Antarctica is crucial for understanding not only the current state of its environment, but also for better understanding of soil development on Earth through time. Our study provides a detailed investigation of micromorphological features and molecular composition of organic matter of soil and soil-like bodies of remote areas of East Antarctica - Larsemann Hills and Bunger Hills, which are characterized by harsh environmental conditions. Studied soils showed predominantly coarse structure and low organic carbon content, alkaline to almost neutral pH range. Thin sections of studied soils were characterized by predominance of grains of quartz, feldspars, and other primary minerals with angular shapes indicating relatively weak degree of their alteration. All studied humic substances are characterized by the predominance of aliphatic structures. Moreover, it was observed that studied humic acids contains significant amounts of carbohydrates, polysaccharides, esters and amino acids and hydrophilic fragments predominate. Organo-mineral interactions were mostly connected with development of biofilms in the topsoil horizons with the maximal biological activity among studied soils.