Geochemical Atlas of Agricultural and Grazing Land Soils
Country / Region: Europa
Begin of project: January 1, 2009
End of project: June 30, 2017
Status of project: November 5, 2011
The geochemical atlas of agricultural and grazing land soils is under preparation (GEMAS). This is essentially a follow-up project of the ‘Geochemical Atlas of Europe’, but concentrating on soil, and the reasons for carrying out this project follow. The administration of REACH (Registration, Evaluation, Authorisation and Restrictions of Chemicals), the new European Chemicals Regulation adopted in December 2006, and the pending EU Soil Protection Directive, require additional knowledge about ‘soil quality’ at the European scale. REACH specifies that industry must prove that it can produce and use its substances safely. Risks, due to the exposure to a substance during production and use at the local, regional and European scale, all need to be reliably assessed. In contrast to human-made organic substances that do not occur naturally in the environment, all industries dealing with natural resources will face in the near future a number of specific questions:
(i) Most of their ‘products’ occur also naturally – the natural background variation needs to be established, in addition to a methodology to differentiate the industrial impact from the natural geogenic background;
(ii) What is the ‘bioavailability’ of metals and other chemical elements in soil? and
(iii) What is the long-term fate of metals and other chemical elements added to soil?
The GEMAS project will deliver good quality and comparable exposure data of metals in agricultural and grazing land soil; in addition soil properties known to influence the bioavailability and toxicity of metals (and other elements) will be determined in soil at the European scale.
The sampling at a density of 1 site / 2500 km2 was completed at the beginning of 2009 by collecting 2211 samples of agricultural soil (Ap-horizon, 0-20 cm, regularly ploughed fields) and 2118 samples from land under permanent grass cover (grazing land soil, 0-10 cm), according to an agreed field protocol (EuroGeoSurveys Geochemistry Working Group, 2008).
All samples were shipped to Slovakia for sample preparation, where they were air dried, sieved to <2 mm using a nylon screen, homogenised and split to subsamples for analysis. They are analysed for (1) 53 chemical elements following an aqua regia extraction, (2) pH in CaCl2, TOC, LOI, grain size (on a selection of samples), total C and total S, (3) total concentrations of 39 elements by X-ray fluorescence, (4) Pb and Sr isotopes, (5) prediction of soil properties by mid infrared (MIR) measurements and (6) determination of Kd values for selected elements on selected samples. The aqua regia results were received in September 2009 and were subjected to a rigorous quality control procedure before their acceptance (Reimann et al., 2009). Because of the complexity of the project, and confidentiality of results, the Geochemical Atlas will be ready by 2013 (Download handout), and an example is given below.
Fig. 1: Geochemical distribution of aqua regia extractable Sr in the <2 mm fraction of agricultural soil (0-20 cm) (Reimann et al., 2009, Fig. 7, p.28)
Source: EGS Geochemistry Expert Group
Distribution of strontium (Sr) in agricultural soil
Natural variation of Sr is large (4 orders of magnitude) and can be reliably mapped as is shown in Figure 1. Nature, geology and climate are the major driving forces for its distribution patterns, while anthropogenic anomalies, as input by fertilisers are not recognisable at this scale. It is clearly indicated that there is not one background value for a sizeable area. Strontium, together with other elements, shows substantially lower concentrations in North than in South European agricultural soil. Surprisingly, recent volcanism (Cyprus, Sicily, mainland Italy) and active fault zones and plate margins are often better indicated by Sr anomalies than some of the major limestone areas, except those of eastern Spain, southern France, Italy, and Paris Basin in France.
.