Investigating the Mineral Composition of Peat by Combining FTIR-ATR and Multivariate Analysis

Abstract

The mineral content of peat has received little attention until the last few decades, when peat cores have been increasingly used to study past dust deposition. Paleodust deposition is commonly reconstructed through elemental datasets, which are used to infer deposition rates, storminess patterns, mineral composition, source identification, and fertilization effects. To date, only a few studies have directly analyzed the mineralogy (by XRD and SEM) and particle size of peat mineral matter, and the conducted studies have usually been constrained by the need to remove a large amount of organic matter, which risks altering the mineral component. One alternative is to use quick, nondestructive techniques, such as FTIR-ATR, that require little sample preparation. In this study, we analyzed by FTIR-ATR both the bulk peat and ash fractions of a sequence taken in a minerogenic mire that covered a wide inorganic matter content range (6%–57%). Aided by principal component analysis on transposed IR spectral data, we were able to identify the main minerals in bulk peat and ash, quartz, mica (likely muscovite), K feldspar (likely microcline), and plagioclase (likely anorthite), which are consistent with the local geology of the mire catchment. Changes in mineral composition during the last ca. 2800 years were coeval with previously reconstructed environmental changes using the same core. Our results suggest that FTIR-ATR has great potential to investigate peat mineral matter and the processes that drive its compositional change.

Eco-Friendly and Effective Diatomaceous Earth/Peat (DEP) Microbial Carriers in the Anaerobic Biodegradation of Food Waste Products

“…The publications of other scientists contain detailed analyses of the FT-IR spectrum of peat, confirming the diversity of natural composition of peat and the presence of characteristic functional groups in its structure, including: hydroxyl groups, O-H; ether groups, C-O; and carbonyl groups, C=O. The presence of a developed aliphatic structure was confirmed by the absorption band derived from the stretching vibrations of C-H bonds [40,53].…”

Storm chasing: Tracking Holocene storminess in southern Sweden using mineral proxies from inland and coastal peat bogs

“…In the transposed PCA each sample is assigned a loading value for each component, and as we used the correlation matrix, the square of the loading (i.e., its partial communality) represents the proportion of the samples' MIR spectral variance that is accounted for by each component. Variations in partial communalities can be taken as a proxy for changes in the relative abundance of the compounds/ minerals along the peat core (Martínez-Cortizas et al, 2021a). However, it is worth noting that the proportion of MIR spectral variance of a mineral in a sample cannot be directly equated to the amount of that mineral present in the sample.…”

Application of mid-infrared spectroscopy for the quantitative and qualitative analysis of organic matter in Holocene sediment records

“…Minerogenic wavenumbers were removed to make the comparison with the organic pyrolytic data more intuitive and because approaches for qualitative and quantitative analysis of mineral matter with MIR has been done elsewhere (e.g. Hahn et al, 2018; Kanbar et al, 2021; Martínez Cortizas et al, 2021a). Their removal does not affect the order of the organic components nor which components the wavenumbers load on, with the exception of one wavenumber for Dragsjön and four for Lång-Älgsjön.…”