D.M.A. Flight

Soil quality assessment under emerging regulatory requirements

New and emerging policies that aim to set standards for protection and sustainable use of soil are likely to require identification of geographical risk/priority areas. Soil degradation can be seen as the change or disturbance in soil quality and it is therefore crucial that soil and soil quality are well understood to protect soils and to meet legislative requirements. To increase this understanding a review of the soil quality definition evaluated its development, with a formal scientific approach to assessment beginning in the 1970s, followed by a period of discussion and refinement. A number of reservations about soil quality assessment expressed in the literature are summarised. Taking concerns into account, a definition of soil quality incorporating soils ability to meet multifunctional requirements, to provide ecosystem services, and the potential for soils to affect other environmental media is described. Assessment using this definition requires a large number of soil function dependent indicators that can be expensive, laborious, prone to error, and problematic in comparison. Findings demonstrate the need for a method that is not function dependent, but uses a number of cross-functional indicators instead. This method to systematically prioritise areas where detailed investigation is required, using a ranking based against a desired level of action, could be relatively quick, easy and cost effective. As such this has potential to fill in gaps and compliment existing monitoring programs and assist in development and implementation of current and future soil protection legislation.

Overbank sediments from central Mexico : an evaluation of their use in regional geochemical mapping and in studies of contamination from modern and historical mining

Abstract Overbank sediment sequences in central Mexico display vertical changes in chemistry which can be related to both anthropogenic contamination and natural geological sources and processes. They also show significant lateral chemical variation, at both local and regional levels, which makes the design of a sampling strategy for regional geochemical mapping or contamination studies difficult. This variation is particularly pronounced in drainage basins which have been contaminated by mining activity and limits the use of overbank sediment as a systematic regional geochemical mapping medium. To be used with confidence, overbank sediments require detailed studies of fluvial geomorphology and history, accompanied by accurate age dating. Active drainage sediments are a more viable alternative in areas of historical mining activity, but must be examined carefully in the light of the regional background where levels of contamination are low or the contaminants are buried within the river floodplain.

Public participation in soil surveys: lessons from a pilot study in England.

In many countries there are policies in place that impact on soils, but very few legislative or policy tools specifically for the protection of soil. Recent EU legislative proposals on soil protection have been met with opposition on the grounds of excessive cost and resource demands. With the need for evidence based policy, and recognition that involving the public in environmental monitoring is an effective way of increasing understanding and commitment, there has been growing interest in soil surveys. In addition, it is accepted that the success of environmental policies depends greatly on how effectively scientists, regulators, stakeholders, and society communicate. This paper presents the Open Air Laboratories (OPAL) Soil and Earthworm Survey as an example of public participation in soil surveys that aims to integrate the above. It is demonstrated how such surveys generate data that can be used to prioritise soil assessment, in order to address some of the concerns and objections to soil protection policies. Lessons from this pilot study in England highlight that with strategic planning of civic participation activities, this approach can deliver improvements in the quality of the evidence collected and allow for effective public involvement in policymaking and implementation, on top of direct educational benefits.

Geochemical mapping of stream water for environmental studies and mineral exploration in the UK

Abstract The stream water hydrogeochemical database, prepared by the British Geological Surveys Geochemical Survey Programme, in conjunction with databases for stream sediments, soil samples and mineral concentrates, has recently been enhanced for a range of economic and environmental objectives. The density of systematic stream water sampling and analysis has been increased to one sample per km 2 and a broader spectrum of determinands introduced. An orientation suite of hydrogeochemical maps has been produced from water samples collected at 1279 sample sites in North Wales to test the methodology. Preliminary results indicate that bedrock geology and mineralisation are the most important variables which influence the surface water chemistry. The primary control by geological parameters is variously modified by secondary influences which include geomorphological factors (especially altitude) atmospheric (climatic and coastal effects), and anthropogenic (agriculture, urban and industrial developments). Regional hydrogeochemical stream water maps have a wide range of economic and environmental applications, especially when interpreted in conjunction with geological data. Results obtained so far indicate that interpretation is likely to be further enhanced in the future by intercomparison with regional stream sediment, hydrogeological, geomorphological, pedological, agricultural, landuse, climatic and remotely sensed datasets in a GIS environment. Hydrogeochemical sampling and analysis represents a cost-effective addition to the Regional Geochemical Survey of the UK.

The geochemistry of niobium and its distribution and relative mobility in agricultural soils of Europe

The Geochemical Mapping of Agricultural and Grazing Land Soil (GEMAS) project provides soil geochemical data for over 50 elements at a density of 1 sample per 2500 km2 across the European continent. Median baseline total concentrations of niobium (Nb) determined by X-ray fluorescence spectrometry in the <2 mm fraction of 2108 ploughed agricultural soil (0–20 cm) and 2024 grazing land (0–10 cm) samples are 13 and 12 mg/kg, respectively. These concentration levels are more than 23 times higher than the median extractable concentration of Nb obtained by aqua regia digestion. Thus >95% of Nb in soils can be considered ‘immobile’. All anomalous soil concentrations can be related to geogenic processes. Many of the elevated Nb concentrations are underlain by Hercynian granitic intrusions and alkaline volcanic rocks. High Nb levels also correspond to the occurrence of residual soils over karst areas of southeast Europe and, to some extent, loess deposits of central and Eastern Europe. Lowest Nb concentrations are found in soils developed on most recent glacial sediments of northern Europe. Comparison of the aqua regia extractable concentrations of Nb in both sample types collected within <450 m of each other show that concentrations are on average 0.12 mg/kg (15.4%) higher in grazing land soils, suggesting an influence of different land-use practises.

High resolution regional hydrogeochemical baseline mapping of stream water of Wales, the Welsh borders and West Midlands region

Abstract The stream water hydrogeochemical database, produced by the Geochemical Baseline Survey (GBASE) of the British Geological Survey, has recently been enhanced in the light of experimental pilot studies in North Wales, to meet a wider range of economic and environmental objectives which require modern, integrated and strategic geochemical surveys for their implementation. Hydrogeochemical data are therefore now collected, in conjunction with geochemical data for stream sediments, soil samples and mineral concentrates. The density of sampling, based on the collection of stream water at near-baseflow conditions during the late summer period each year, has been increased to one site per 1.75 km 2 and a broader spectrum of geochemical determinants introduced. Provisional regional datasets are being prepared for an extensive region covering Wales, the Welsh Borders, and part of the West Midlands representing over 17 000 sample sites. Bedrock geology and base metal sulphide mineralisation are particularly well reflected in the stream water chemistry at the regional scale. The influence of secondary factors, such as geomorphology, atmospheric controls, and anthropogenic contamination due to agriculture, urban, industrial and military developments, can also be readily distinguished. The data obtained by systematic high resolution sampling of first and second order streams, vary in concentration over three or four orders of magnitude for many of the analytes studied here. This compares with a range of only one or two orders of magnitude for many of the analytes in stream sediment samples. The extended range in values for stream water is an important factor in the gridding, plotting and production of relatively stable maps. They are relatively unaffected either by short temporal changes in stream water flow, which are attributable either to storm events noted during the sampling campaign, or by annual differences between wet and dry summers in different years. This has enabled a series of robust surface hydrogeochemical maps to be prepared for analytical data collected during the summer sampling campaigns conducted annually from 1989 to 1994. These maps provide a unique source of synoptic baseline information for a wide range of economic and environmental applications especially, when combined with other geoscience datasets in a GIS environment.

THE COLLECTION OF DRAINAGE SAMPLES FOR ENVIRONMENTAL ANALYSES FROM ACTIVE STREAM CHANNELS

The collection of drainage samples from active stream channels for geochemical mapping is now a well-established procedure that has readily been adapted for environmental studies. This account details the sampling methods used by the British Geological Survey in order to establish a geochemical baseline for the land area of Great Britain. This involves the collection of stream sediments, waters and panned heavy mineral concentrates for inorganic chemical analysis. The methods have been adapted and used in many different environments around the world. Detailed sampling protocols are given and sampling strategy, equipment and quality control are discussed.

Regional geochemical comparisons from the Lower Palaeozoic, Southern Uplands-Down-Longford terrane in Northern Ireland and Scotland

Synopsis Newly-acquired regional geochemical data for the Down-Armagh (Northern Ireland) sector of the Southern Uplands–Down-Longford terrane are assessed by comparison with the equivalent dataset for southern Scotland. Despite the much thicker glacigenic cover to the Down-Armagh bedrock, the principal geochemical lineaments identified in the Southern Uplands are still apparent. Patterns of element distribution emphasize the continuity of structure and stratigraphy between the two regions, with Cr, Zr, Sr, Rb, Ba and Ca (as CaO) proving particularly instructive. Much of the Down-Armagh outcrop consists of Llandovery strata from the Gala and Hawick Groups, so it is this part of the terrane that is most closely considered. Though continuity is clear, there is a suggestion of additional structural imbrication in Down-Armagh, whilst variability in the defining element ratios suggests along-strike compositional changes in the turbidite sandstones. These changes may be controlled by lithostratigraphical variation in sedimentary provenance, or may be influenced by the dominant palaeocurrent flow towards the SW, which has resulted in a broadly more distal and mature Llandovery turbidite lithofacies in Down-Armagh than in the Southern Uplands.

Data Conditioning of Environmental Geochemical Data: Quality Control Procedures Used in the British Geological Survey's Regional Geochemical Mapping Project

Abstract Data conditioning procedures involve the verification, quality control and data levelling processes that are necessary to make data fit for the purpose for which it is to be used. It is something that has to be planned at the outset of any project generating geochemical data. Whether it is in the sampling phase, for example, determining how sites and samples should have a unique identity, or through to the data presentation phase in which disparate data sets may have to be joined to form a seamless map. This account describes the methods currently used by the British Geological Surveys regional geochemical mapping project that has been generating geochemical data for various sample media for nearly 40 years. It is important that users of the data are given information that will help them ascertain whether the provided environmental data is suitable for the purpose of its intended use.

The identification of mining related contamination in the UK using high resolution geochemical mapping: examples from Northeast England and North Wales.

The Geochemical Survey programme (GSP) of the BGS is currently undertaking the systematic multi-element regional geochemical mapping of the UK landmass.