Sensitivity of sediment geochemical proxies to coring location and corer type in a large lake: Implications for paleolimnological reconstruction

Abstract

We compared a suite of geochemical proxies in sediment cores collected in 1982, 1988, 1991, and 2003 from sites near the depocenter of Lake Erie to evaluate the reliability of paleoenvironmental reconstructions derived from lacustrine sediments. Our proxies included the concentrations and carbon isotopic compositions of organic and inorganic carbon (TOC, CaCO 3 , d13 C org , and d 13C CaCO3 ), augmented by organic C to total N ratios (C org it difficult to extract consistent environment information from different cores. Our findings suggest that in addition to temporal environmental changes, high-resolution paleolimnological reconstruction is sensitive to many factors that could include spatial sediment heterogeneity, discontinuous sedimentation processes, bioturbation, sediment dating uncertainty, and artifacts associated with analytical and coring procedures. Therefore, multiple-core sampling and analysis are important in reliably reconstructing environmental changes, particularly for large, heterogeneous lacustrine basins.

Complexities of Stable Carbon and Nitrogen Isotope Biogeochemistry in Ancient Freshwater Ecosystems: Implications for the Study of Past Subsistence and Environmental Change

“…In comparison with sediments, archaeological fauna record environmental change from a different ecological perspective and data interpretation are subject to a different set of strengths and weaknesses, making them potentially complementary (Guiry et al, submitted). For instance, variability associated with short term intra-annual oscillations in environmental conditions, sediment mixing, and diagenesis that may complicate interpretations of time series composed from sediment isotopic compositions (Lehmann et al, 2002;Lu et al, 2014) may not present a significant issue when analyzing bone collagen isotopic compositions (which provide an inter-annual average) from longer-lived fauna-a quality which can lend a degree of temporal stability to a data set (Guiry et al, 2018). In this context, the prospect for exploring past climate change through isotopic analyses of time series of aquatic fauna, such as fish and birds from archaeological sources, is worthy of closer consideration.…”

Perspectives on My Career in Organic Geochemistry

“…The sediment sequences in the cored locations, although as close together in the smooth depocenter of the lake as navigation systems could achieve, were not identical. Instead, their properties indicated that bottom currents had winnowed the sediments (Lu et al., 2014). This phenomenon has been reported in other lakes and the deep sea, and it can both be a challenge and a source of new information to paleolimnological and paleoceanographic reconstructions.…”

Organic carbon accumulation and productivity over the past 130 years in Lake Kawaguchi (central Japan) reconstructed using organic geochemical proxies

“…To date, only a limited number of studies have compared more than one core from a single lake (Wang et al 2009;Lu et al 2014;Sarkar et al 2014;Kumar et al 2016). However, these studies strongly suggested that a single core is insufficient to represent a whole lake environment due to the spatial variability of sediment distribution.…”