A novel environmental geochemistry tool has been developed. Landscape Geochemistry (LG) is now combined with state-of-the-art spatial modelling with GIS. Current research includes combination of LG and advanced landscape metrics for geochemical barrier identification and contamination transport efficiency in catchments. LG spatial analysis is also combined with catchment hydrological and sediment transport models. Current activities are limited to the catchment scale (geochemical landscapes) and on mining related contamination problems.
Consistent geochemical mapping TERMINOLOGY now available!
Jordan & Szucs (2011) developed a consistent geochemical mapping terminology such as ‘anomaly’ and ‘geochemical background’:
Geochemical abundance is the measurement of element concentrations in a particular landscape component.
Total abundance and partial abundance
Total and partial abundances are total recoverable element concentration and the speciation of elements among certain phases (such as clay minerals, organic matter and pore water) in the collected sample, respectively. A partial abundance value or ‘partitioning coefficient’ is often used in risk assessment models of chemicals.
Relative abundance (enrichment and depletion)
Relative abundance is further distinguished, giving the element concentration related to a reference value such as concentration normalised to average precipitation or to sea water composition, or to other elements or element associations. A chemical substance can be enriched or depleted in a certain environment if its concentration relative to some reference is higher or lower.
The concentration of a chemical substance integrated over a volume of landscape gives the bulk abundance, i.e. the total mass content of the sample. Bulk abundance has a key role in contaminant risk assessment: a large land with low contaminant concentration (a non-point source) around a mine site may act as the same contamination risk source as a small spot of mine waste rock dump with high contamination concentration (point-source).
Geochemical signature is a certain association of chemical elements, i.e. the characteristic abundances of elements relative to each other.
Geochemical zones (also called geochemical provinces) are areas with characteristic geochemical signatures. These areas are often associated with ore mineralization in the bedrock and can include polluted lands or stream sections, for example.
Geochemical baseline is defined as the environmental conditions at a given time, regardless of the nature and extent of man’s activities. A baseline is chosen operationally and then serves as a reference point for future investigations or monitoring.
Natural geochemical background
Natural geochemical background is the original conditions of the environment prior to any influence of man’s activities. In areas with minimal anthropogenic influence the baseline is the same as the background. Baseline and natural background concentrations are defined for a given location (e.g. stream water monitoring point), but they can be extrapolated for an area (regional baseline and background).
Geochemical anomaly refers to unusually high or low geochemical abundance relative to the surrounding environment, called the geochemical background. Anomaly can be in the baseline (for example due to human pollution) and in the natural background (due to ore mineralization in bedrock) as well. Baseline, background and anomaly can be defined for any of the landscape components and for total, partial or relative abundances.
Contamination and deficiency
Contamination and deficiency refer to high and low geochemical abundances, respectively, posing risk of harmful effects to human health or to ecosystems. Contamination (and deficiency) can be caused by human activity or by natural background processes as well.
Man-made supply of substances to the natural environment (natural geochemical background) is pollution.
Geochemical gradient (geochemical breakline)
Geochemical gradient refers to the systematic and gradual changes of environmental parameters, including geochemical abundances of chemical substances. Gradients are the results of spatial and/or temporal trends and are scale dependent. Gradients drive geochemical flows such as contaminant transport along topographic gradients or along concentration gradients in the vertical soil profile, for example. Data on geochemical abundance is used for inter- and extrapolation to describe gradients of chemical elements that reflect transport processes. This is the subject of geochemical mapping. Gradual change along a gradient can seem a sharp boundary at a coarser scale. A sharp or abrupt change of environmental parameters at a given scale is a geochemical breakline.
Absolute mobility is defined as the rate at which elements are brought into chemical reactions. For example, some elements can have higher solubility than others in water-rock interaction and thus they may become more available for contamination risk.
Specific mobility is the rate at which elements are brought into chemical reactions in a specific geochemical environment. Specific mobility can change with changing environmental conditions: mobility of metals bound to organic matter can increase upon acidification of the environment, for example.
Relative mobility is further distinguished, giving the absolute or specific mobility of an element compared to the mobility of another element. Often conservative (non-reactive) elements such as Cl are used as references to characterise the relative mobility of other elements in the same environment. Low mobility or stability of a pollutant in a given environment decreases contamination risk at human health or ecosystem. Partial and relative abundances of the element measured in various landscape components or phases, such as in the bedrock and in the contacting water, are often used to describe the specific mobility of elements in the given landscape.
For more see Publications.
Jordan G. and A. Szucs, 2011. Geochemical Landscape Analysis: Development and Application to the Risk Assessment of Acid Mine Drainage. A Case Study in Central Sweden. Landscape Research, 36:231-261.
LANDSCAPE METRICS & SEDIMENT TRANSPORT MODELS PAPERS:
Jordan G., A. van Rompaey, A. Somody, U. Fügedi, M. Bats, and A. Farsang, 2009. Spatial Modelling of Contamination in a Catchment Area Impacted by Mining: a Case Study for the Recsk Copper Mines, Hungary. Journal of Land Contamination and Reclamation, 17:415-424.
Jordan G., van Rompaey A., Szilassi P., Csillag G., Mannaerts C. and Woldai T., 2005. Historical land use changes and their impact on sediment fluxes in the Balaton basin (Hungary). Agriculture, Ecosystems & Environment, 108:119-133.
Szilassi P., Jordan G., van Rompaey A. and Csillag G., 2005. Impacts of historical land use changes on erosion and agricultural soil properties in the Kali Basin at Lake Balaton, Hungary. CATENA, 68:96-108.
See Publications for papers.
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INTRODUCING LANDSCAPE GEOCHEMISTRY:
Landscape Geochemistry provides methodological framework and practical techniques for linking environmental geochemical process and landscape scale structures in order to assist land management and spatial planning. Geochemical landscape analysis studies the flow of chemical entities in the supergene zone and how these flows interact with landscapes and ecosystems based on the principle that geochemical flow is important in landscape evolution as being the principle link between biotic and abiotic components. Geochemical landscape analysis studies processes at all scales but focus is on the landscape mosaic (soil patch) because this is the primary scale of human activity and decision making. Elementary landscape, the smallest landscape geochemical unit is defined by the soil type and ‘geochemical landscape’ denotes the association of the elementary landscapes connected by material flow.
The 7 principles of landscape geochemistry are the concepts of
- geochemical abundance,
- geochemical gradients,
- element migration,
- geochemical flow,
- geochemical barriers,
- geochemical landscape classification and
- historical geochemistry,
together with the principles of hierarchy, similar to landscape ecology. Perelman (1986) developed the powerful tool of landscape geochemical barriers and Glazovskaya (1963) developed the basics of geochemical landscape classification. Traditional landscape geochemistry is limited by the lack of application of geochemical transport and reaction models, lack of use of GIS technology and lack of link with landscape ecology. Geochemical landscape analysis answers questions such as where the contamination in the landscape is and in what form and phase, how stable it is, which are the contamination transport processes, what is the relationship of contamination to other chemical element cycles and to other landscapes and ecosystems, how land use change affects geochemical processes, and where and what kind of geochemical reaction and transport control elements such as barriers and corridors are present in the landscape that can be used for contamination risk management.