Abstract
An existing steady state model of lake phosphorus (P) budgets has been adapted to allow reconstruction of long-term average historic lake water total phosphorus (TP) concentrations using lake sediment records of P burial. This model can be applied without site-specific parameterisation, thus potentially having universal application. In principle, it is applicable at any site where there is both a sediment P burial record and knowledge of the current water budget, although we advise caution applying it to problematic sediment records. Tested at six published case study sites, modelled lake water TP concentrations agree well with water-quality monitoring data, and limited testing finds good agreement with wholly independent diatom inferred lake water TP. Our findings, together with a review of the literature, suggest that well preserved lake sediments can usefully record a long-term average P burial rate from which the long-term mean lake water TP can be reliably estimated. These lake water TP reconstructions can provide meaningful site-specific reference values to support decision making in lake eutrophication management, including establishing targets for lake restoration.
Highlights
Excess phosphorus (P) loading and the resulting eutrophication of waterbodies is a problem that affects aquatic ecosystems globally
We present a geochemical method for reconstructing long-term average water total phosphorus (TP) concentrations based on lake sediment P burial fluxes, an approach which in principle is universally applicable at sites with well-preserved sediment records
In principle the model is applicable at any site where there is both a sediment P burial record and knowledge of the current water budget, as discussed above we advise caution applying it to problematic sediment records
Summary
Excess phosphorus (P) loading and the resulting eutrophication of waterbodies is a problem that affects aquatic ecosystems globally. Current approaches use palaeoecological records as indicators of change, where transfer functions can turn a microfossil assemblage into a record of past water quality, with diatom records the most common way of reconstructing lake water total phosphorus (TP) (Cumming et al 2015). This palaeoecological approach requires a time and resource-intensive tailored training set, and has the disadvantage that microfossil records do not preserve in all lakes. The validity of the transfer function approach has been questioned on theoretical grounds (Juggins 2013)
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