Lacustrine Archives of Metals from Mining and Other Industrial Activities—A Geochemical Approach

Abstract

Since the first studies reporting recent stratigraphic changes of metal concentration in lake sediments, many hundreds of studies have been published in the peer-reviewed literature. It is an impossible task to do justice to all of these works here; instead we: (1) examine recent methodological advances and place these in the context of the historical development of the discipline; and (2) explore the various purposes to which such methods have been applied. Such a historical emphasis may appear in conflict with the needs of a review of new approaches; however, this is not in fact the case for two main reasons. First, most new advances supplement rather than replace traditional methods, such that a thorough understanding of the practical and theoretical issues impacting these is still essential for reliable interpretation of palaeolimnological data. Second, while many of the new methods purport to circumvent problems, they achieve this only under favourable conditions, not dissimilar to the conditions that influence the earlier methods, so the same lesson must be learned anyway. Consequently, we use this historical narrative to address the fundamentals of the discipline.The chapter comprises two main parts; methodology and applications. The methodological section has three subsections: (1) Introduction to processes controlling natural variations in metal fluxes and concentrations in lake sediments; (2) Measurement of metal concentrations in sediments; (3) Calculation of enrichment or fluxes from sediment metal concentration data.There are four main applications subsections focusing on the value of lake sediment records of metals derived from mining or industry. They are: (1) Geochronological markers in sediments providing chronology for other research goals; (2) Lake sediment heavy metal records to quantify pollution loading histories, or to

The geomorphology of the Anthropocene: emergence, status and implications

“…Globally, however, some floodplains possess stratigraphic units attributable to anthropogenically‐enhanced soil erosion, principally overbank loams that host archaeological remains (Brown, , ) (Figure ). A similar anthropogenic stratigraphy may also be recorded in lake sediment archives (Dearing and Jones, ), possibly in association with anthropogenic geochemical (Boyle et al , ) or even DNA signatures (Taberlet et al , ). In extensively studied regions such as northwest Europe, the Mediterranean and North America, such floodplain and lake stratigraphic markers are diachronous, the timing of anthropogenic increases in soil erosion being dependent on the regional history of deforestation and agriculture.…”

The fate of atmospheric metal pollutants in the landscape, Snowy Mountains, south-eastern Australia

“…This constitutes a significant gap in understanding because geomorphic processes, which themselves vary across the landscape, may mobilize and transport atmospherically derived metals between landscape stores, in the process modifying the concentration of anthropogenic metals relative to matrix materials (Boyle et al, 2015). In addition, increases in metal contaminants may be masked by the supply of naturally generated metals at concentrations that are high relative to those of the excess metal (Stromsoe et al, 2013).…”

“…At remote sites, the abundance of anthropogenic metals may be orders of magnitude lower than in more polluted areas (Boyle et al, 2015). Consequently examining concentrations alone is not usually sufficient to distinguish anthropogenic contamination from naturally occurring metals.…”

“…The use of lake sediments to reconstruct past rates of regional atmospheric deposition is predicated on the assumption that metals are incorporated into sediments in direct proportion to atmospheric emissions (Boyle et al, 2015). This is more likely to be the case in lakes where the overall rate and background variability of metal transport from the catchment is low (e.g.…”

“…This is controlled by: 1) metal solubility, i.e. the ease by which an element dissolved in the soil solution to be leached from soil, and/or re-precipitated in the soil itself or in another environment (this is influenced by redox potential and soil pH); 2) size fractionation of sediment during transport leading to either concentration or dilution of pollutant metals depending on the transport regime, due to the preferential association of industrial metals with clay and silt sized grains or; 3) concentration/dilution due to early diagenesis or the transport of matrix minerals, causing post-depositional enrichment/depletion within the profile (Boyle et al, 2015). Thus, the concentration of metals in some archives may not directly reflect the rate of atmospheric deposition.…”