Geochemical properties of aquifers and other geological formations in the UK

Milne, C.J.; Kinniburgh, D.G.. 2012 Geochemical properties of aquifers and other geological formations in the UK. Nottingham, UK, British Geological Survey, 255pp. (OR/12/090) (Unpublished)

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Abstract/Summary

The intrinsic geochemical characteristics of geological for-mations have a considerable influence in controlling solute and pollutant transport behaviour during groundwater flow through the shallow geosphere. The interactions between solute or pollutants and the surface geochemistry of the rock matrix will often determine both the extent and speed of solute transport in the saturated and unsaturated zones. Consequently, understanding these processes is of critical importance for a range of environmental management re-quirements, such as landfill leachate monitoring or contam-inated land evaluation, including requirements related to statutory obligations for ensuring good groundwater status under the EU Water Framework Directive. Risk assessment and management approaches frequent-ly make use of numerical geochemical modelling to predict contaminant transport. These models necessarily require parameterization of the geochemical properties of the geo-logical formations involved and the predictions which can be obtained are inevitably only as good as the quality of the data which are used. However, the natural variation in li-thologies and extensive spatial heterogeneities of the UK rock formations result in considerable variability of the most important geochemical properties. Identifying or ob-taining good relevant data for calculations can be difficult; new laboratory measurements can be expensive and time-consuming, published data are relatively sparse and existing data from previous site investigations are often held com-mercially and are difficult to get hold of. This study, supported by the British Geological Survey and the Environment Agency, presents the first comprehen-sive national compilation of geochemical properties data of relevance to geochemical modelling. An assessment has been made of existing available primary data. Relatively few data are available, but those which are have been col-lated. To underpin this the project has undertaken an exten-sive programme of new experimental measurements on the geochemical properties of samples from geological for-mations across the country. Initially attention was focussed on England and Wales, but this was later expanded to in-clude data and samples from Scotland. Over 600 new sam-ples have been included, providing by far the largest high-quality internally-consistent dataset currently available for these parameters. The geochemical properties addressed are those consid-ered to be of greatest significance for the purposes of mod-elling and risk assessment, namely: • cation exchange capacity (CEC); • fractions of organic and inorganic carbon (fOC, fIC); • extractable (readily soluble) element contents of iron (Fe), manganese (Mn) and sulphur (S); • whole-rock and clay-fraction mineralogy. It is intended that the Geochemical Properties Manual rep-resented by this report and database should provide a relia-ble reference resource for practitioners carrying out site in-vestigations in the future. Whilst site-specific parameter measurements will always provide the greatest confidence, this manual will provide a benchmark of what is known and what can reasonably be expected for the geochemical prop-erties of given types of geological formations. In this re-spect the manual is related to the manuals of physical prop-erties of major and minor aquifers produced by BGS previ-ously. However, for geochemical properties date have been included for any geological formations, not only aquifers, as aquitards and aquicludes also play an important role in constraining transport behaviour. Chapters 1 and 2 of the report introduce the data compi-lation, structure and presentation. Chapters 3 and 4 provide a brief overview of the principles of geochemical modelling and of the use of geochemical data in geochemical model-ling. Chapters 5-8 then provide the bulk of the report, cata-loguing the available data by geology for a selection of the key geochemical parameters relevant to numerical model-ling. The data are presented as numerical and graphical sta-tistical summaries to try to assist the user in finding the most suitable parameter values to use in their own circum-stances. This report (OR/12/090) supersedes an earlier version (CR/06/216N) which is now withdrawn. It contains some corrections, updated lithostratigraphical classifications and additional data added to the database up to the end of De-cember 2012.

Item Type:	Publication - Report
Funders/Sponsors:	British Geological Survey, Environment Agency
Additional Information. Not used in RCUK Gateway to Research.:	This item has been internally reviewed, but not externally peer-reviewed.
Additional Keywords:	GroundwaterBGS, Groundwater
Date made live:	24 May 2022 13:25 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/532664

Item Type:

Publication - Report

Funders/Sponsors:

British Geological Survey, Environment Agency

Additional Information. Not used in RCUK Gateway to Research.:

This item has been internally reviewed, but not externally peer-reviewed.

Additional Keywords:

GroundwaterBGS, Groundwater

Date made live:

24 May 2022 13:25 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/532664