Challenges in Interpreting Geochemical Data: An Appraisal of Analytical Techniques Applied to a Karstic Lake Sediment Record

Aritina Haliuc,Alicja Bonk,Jack Longman,Simon M Hutchinson,Michal Zak,Daniel Veres

doi:10.3390/w14050806

Abstract

The paleoclimatic and paleoenvironmental changes inferred from shifts in lake sediment geochemistry require reliable, efficient and cost-effective methods of analysis. The available geochemical techniques, however, suggest that different analytical approaches can influence data interpretation. X-ray fluorescence core scanner analyses (XRF-CS), field portable X-ray fluorescence (FPXRF) and inductively coupled plasma optical emission spectrometry (ICP-OES) were concurrently applied to provide a multi-method geochemical appraisal of a 6000-year-long karstic sediment record (Lake Ighiel, Romania). The comparison between techniques was based on a set of elements that are widely employed in environmental reconstructions (Ti, K, Fe, Ca). Descriptive and statistical approaches were used to assess the advantages and disadvantages of each method and assess their optimal use in karstic environments. Our data display similar downcore patterns, with strong to moderate correlations between the datasets. The discrepancies observed between method-specific downcore multi element behaviour are related to the preparation steps and sampling. To best capture the complexity of past environmental changes in karstic settings, a combination of quantitative and qualitative geochemical methods would be the most appropriate approach to reliable data acquisition and subsequent paleoenvironmental interpretation of lake sediment data.

Highlights

To ensure high data reproducibility, the analysis focused on explored the relationship between X-ray fluorescence core scanner analyses (XRF-CS), field portable X-ray fluorescence (FPXRF) and inductively coupled plasma optical emission spectrometry (ICP-OES) data obtained from a assessing the patterns in a set of lithogenic indicators, Ti, K, Ca, Fe
For elements included in the study, the relative percent difference (RPD) between the concentration of the reference material and the concentration measured by FPXRF was less than 10%
XRF-CS provides a detailed view of the chemical composition of the scanned sediment, XRF-CS provides a detailed view of the chemical composition of the scanned sedibut this is hampered by background noise and is highly sensitive to organic matter content, ment, but this is hampered by background noise and is highly sensitive to organic matter which can mask the lithogenic fraction [31,52]

Summary

Introduction

Lake sediments are among the most valuable records when unravelling local to regional environmental changes over time [1–3]. A proliferation in the availability of quantitative and qualitative geochemical analyses has resulted in a range of high-resolution research studies aiming to better understand long- and short-term lacustrine changes in relation to climate variability and human impacts. These studies focused on a variety of topics such as past climate variability [4], land-use changes [5,6], catchment dynamics, sediment delivery and lake responses [7–12], identifying rapid depositional events [13] and assessing the rate and amplitude of anthropogenic impacts [14–17]

Results

Discussion

Conclusion