Phosphorus reference concentrations in European lakes

Abstract

As part of an assessment of the ecological quality of surface waters, recent European water legislation, the water framework directive (WFD), requires the setting of environmental objectives for particular chemicals. As part of this, many European countries are choosing to develop a quality classification scheme for total phosphorus (TP) concentration. The assessment of ecological quality and its component parts, such as TP, must be based on the degree of divergence of a water body from an appropriate baseline, or 'reference condition'. For this reason, it is important to determine TP reference conditions for all lake types, or alternatively, models for predicting reference TP concentrations on a site-specific basis. With this purpose in mind, we have assembled a large dataset of European lakes considered to be in reference condition; 567 lakes in total. Data has been collated on TP concentration, mean depth, alkalinity, humic type, altitude, area, and geographical region. Reference TP concentrations have been derived from this dataset using two empirical approaches. Firstly, lake-type specific TP reference conditions were derived simply from descriptive statistics (median and percentiles) of TP concentrations by lake type. Secondly, empirical models were developed for estimating sitespecific reference TP concentrations from a set of potential predictor variables. TP concentrations were found to vary with lake type and by geographical region. TP increased with colour and alkalinity, and decreased with lake depth and altitude. There was no clear relationship between TP and lake area. Altitude, mean depth and alkalinity were selected as independent explanatory variables for prediction of site-specific reference TP concentrations, with different models developed for humic and non-humic lakes. A simpler site-specific predictive model based solely on the morphoedaphic index (MEI) (a combination of a site's alkalinity and mean depth) was also shown to be comparably effective.

A model‐based assessment of non‐compliance of phosphorus standards for lakes in England and Wales

“…A European version of the Morpho-Edaphic Index (MEI) by Vighi and Chiaudani (1985) was developed from a database of more than 500 European reference lakes (Cardoso et al, 2007) for site-specific standards. Site specific standards were available for about 160 lakes in England and Wales with known depth and alkalinity data.…”

“…Site specific standards were available for about 160 lakes in England and Wales with known depth and alkalinity data. All lakes used the clear-water MEI model outlined in Cardoso et al (2007). Where depth and alkalinity were not known, type-specific standards were used.…”

“…Type specific phosphorus concentrations for good ecological status were developed by Cardoso et al (2007) from a database of over 500 European reference lakes. The phosphorus good/moderate boundary was set based on ecologic impact and derived from the chlorophyll Table 4 Type specific annual mean total phosphorus concentrations (µg l -1 TP) at lake status boundaries used in this study good/moderate boundary using TP-Chlorophyll regression relationships (Phillips et al, 2008).…”

The use of diatom records to establish reference conditions for UK lakes subject to eutrophication

“…In contrast, within the medium and high Indeed the strength of this relationship led Vighi and Chiaudani (1985) to construct the morphoedaphic index (MEI) which predicts background TP concentrations based on the ratio between total dissolved solids, as measured by alkalinity or conductivity, to lake mean depth. In an analysis of data from over 500 European reference lakes, Cardoso et al (2007) observed that TP increased with alkalinity and declined with depth and a similar conclusion was drawn from the examination of over 1000 TP observations from a range of lake types across Europe ). Owing to the strong relationship between TP and chlorophyll a in these lakes ) chlorophyll a similarly varies with lake type such that reference concentrations are highest in high alkalinity, shallow lakes and are lowest in low alkalinity, deep lakes ).…”

Palaeolimnology without a core: 153 years of diatoms and cultural environmental change in a shallow lowland lake (Belgium).

“…As such, their restoration target may correspond to the good status required for the most pertinent natural lake-water type or deviate ± considerably due to societal restraints. So far, reference conditions for natural, often stratified lakes have drawn most attention (bennion et al 2003, LyCHe soLHeiM 2005, Leira et al 2006, CarDoso et al 2007) and ecological potential was addressed more sparingly (e.g. LaMMens et al 2008), even though it probably pertains to a majority of lowland water bodies.…”