Project
Puzzling organic matter fractions: Characterization of Hy and HON fractions
Organic matter plays a key role in multiple organo-geochemical processes both in the natural environment and organic waste systems (e.g. compost heaps or landfills). A key role of organic matter is that of a reactive surface to which major and minor elements (nutrients, contaminants) can bind.
Background
Organic matter contributes both to the mobilisation of elements (when present as dissolved organic matter) and immobilisation of elements (when present as solid organic matter). While fully elucidating the role of organic matter is of utmost importance, its intrinsic heterogeneity makes characterisation (and thus understanding) of organic matter challenging, which has led to a plethora of analytical techniques.
One such method has been developed by Van Zomeren and Comans (2007), in which organic matter is fractionated in several operationally defined humic substances: humin, humic acid (HA), fulvic acid (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). The HA and FA fractions have been shown to enable adequate modelling of major and minor element binding to organic matter in soil systems. For this reason HA and FA fractions and their dynamics have been extensively studied. The Hy and HON fractions have received little attention. Yet, composts and landfills have shown to be systems where Hy and HON fractions are, based on carbon content, a considerable fraction of the total humic substances concentration. The Hy fraction might be especially important in the dissolved organic matter fraction that increases the mobility of major and minor elements. The HON fraction is an even less studied fraction that might play an important role in the dynamics of solid organic matter. Yet, due to the fractionation technique the HON fraction is the hardest to isolate and thus the least studied.
The aim of this MSc thesis is to gain a better understanding of the structural composition and binding characteristics of either the Hy or HON fraction in organic waste systems and possibly compare them to soil systems. The composition of these fractions can be characterised by a range of to be further determined analytical techniques. A few proposed techniques could include Py-GC/MS, FTIR or solid-state NMR. Reactivity of the Hy and HON fraction might be explored using proton titration.
The results of this MSc thesis will provide fundamental insights in the structure and characteristics of an understudied organic matter fraction (Hy, HON). These insights are essential for better management of organic waste systems to limit contamination of the environment by these systems.
Used skills
- Literature review;
- Proposal and thesis writing;
- Laboratory work;
- Data analyses.
Requirements
- SOC81336 Soil Chemistry and Chemical Soil Quality