Spectromicroscopy Mapping of Colloidal/Particulate Organic Matter in Lake Brienz, Switzerland

Abstract

Transmission electron microscopy (TEM), soft X-ray scanning transmission X-ray microscopy (STXM), and mu-FTIR spectromicroscopy were used to map colloidal/ particulate material in an ultra-oligotrophic lake, Lake Brienz, Switzerland, with a special focus on organic functionality. Within the statistical margin of error and the uncertainties arising from the representativeness of the results, the research reveals that organic material was associated with potassium-rich inorganic colloids present in surface and deep water (depths of 1 and 100 m, respectively), which indicates a vertical transfer of aggregates by sedimentation. Pure organic colloids could only be detected in surface waters. In addition, correlation map analysis of synchrotron-based mu-FTIR and carbon K-edge STXM spectromicroscopic data using spectra from the Lütschine and Aare Rivers as target spectra revealed spectral similarities with organic components from both tributary rivers in deeper regions (100 m) of the lake. The results prove that STXM and mu-FTIR can characterize colloidal and particulate organic material in low organic carbon systems.

Organic Carbon Chemistry in Soils Observed by Synchrotron-Based Spectroscopy

“…Increased abundance of heterocyclic N in organomineral admixtures as compared to coatings and microbial matter ) also points at cyclic organic matter playing a role in the formation of organomineral interactions. Some indications also exist from research on lake colloids where organic matter associated with minerals was characterized by greater proportions of aromatic C (Schäfer et al, 2007). This will need to be tested more rigorously in the future for soil organic C interactions with different minerals.…”

Bentonite Nanoparticle Stability and the Effect of Fulvic Acids: Experiments and Modelling

“…In order to verify the fulvic acid surface association with montmorillonite colloids at pH 6 and 8, aliquots of the investigated suspensions were ultracentrifuged, and the settlements were investigated by carbon K-edge STXM. The STXM method has been tested in various environmental systems, including (a) natural particulate matter of ultra-oligotrophic lakes [63], (b) distribution of natural organic matter in low carbon claystone formations [64], (c) chemical characterisation of natural organic matter, humic and fulvic acids [65], and (d) their fractionation through metal complexation or mineral interaction [65][66][67], which proved to be a very sensitive technique.…”

Molecular Composition of Humic Acids from Coastal Wetland Soils along a Salinity Gradient

“…Th eir amphipathic nature enables them to interact with a wide variety of inorganic and organic pollutants including heavy metals and charged organic pollutants via chemical bonding and with nonpolar organics through nonspecifi c physical interactions (Li et al, 2003). Interaction between humic substances and inorganic mineral phases leads to the formation of organic coatings/complexes on mineral phases and a change in surface charge (Kleber et al, 2007;Schäfer et al, 2007). In addition, different types of humic substances with diff erent functionalities could exert contrasting infl uences on mineral colloid coagulation (Schäfer et al, 2007).…”

“…Interaction between humic substances and inorganic mineral phases leads to the formation of organic coatings/complexes on mineral phases and a change in surface charge (Kleber et al, 2007;Schäfer et al, 2007). In addition, different types of humic substances with diff erent functionalities could exert contrasting infl uences on mineral colloid coagulation (Schäfer et al, 2007). Hence, understanding the molecular composition of SOM in a given soil will be of great utility in elucidating reaction mechanisms of humic substances with mineral surfaces as well as their role in contaminant transport.…”