SEGH Articles

# Urban Geochemical Mapping by the Geochemistry Expert Group of EuroGeoSurveys

25 March 2016
Given the fact that by 2050 more than 80% of the European population will be living in cities (United Nations, 2014), the quality of the urban environment is becoming an important issue in the 21st century.

Given the fact that by 2050 more than 80% of the European population will be living in cities (United Nations, 2014), the quality of the urban environment is becoming an important issue in the 21st century. Ever since the industrial revolution, with a peak after the Second World War, the urban environment has been contaminated with many toxic elements and compounds, which are being emitted by a wide variety of human activities (industry, traffic, domestic heating, coal and oil combustion, incineration, construction activities, etc.),  and often accumulate in urban soil.

Since, the 1970s a conscious attempt is being made in many countries to develop industrial estates outside the residential, commercial, and recreational parts of cities. Within the urban structure remain, however, the brownfield sites, and the enormous problem of their redevelopment in order to reduce the pressure on greenfield sites.  As many health-related problems are linked to the state of the urban environment, the European citizens want to know the geochemistry of the land their houses are built on. Moreover, it is very important that the chemical quality of soil in public places, such as schoolyards, parks, playgrounds, kindergartens, recreation areas, and workplaces is known. Estate agents need to know the quality of the land they are marketing, and insurance brokers the potential risks to their customers.

The Geochemistry Expert Group of EuroGeoSurveys realising that knowledge about soil contamination, geochemical background concentrations, and detailed spatial element distribution is becoming a key issue in urban planning initiated in 2008 an Urban Geochemistry project with the acronym URGE.  The first part was the compilation of all hitherto knowledge and its publication in a full-colour textbook “Mapping the Chemical Environment of Urban Areas” (Johnson et al., 2011):

The first part of the textbook covers more general aspects of urban chemical mapping, with an overview of current practice, and reviews of different features of the component methodologies (chemical analysis, quality control, data interpretation and presentation, risk assessment, etc.). The second part includes a number of case studies from different urban areas, principally from Europe, but with some contributions from North America, Africa and Asia.  Many of the chapters discuss the potential impact on human health and describe the multi-disciplinary effort, usually supported by legislation, required to deal with the legacy of contamination found in many urban areas.

Apart from the publication of the textbook, different urban geochemical projects were carried out in different European cities, and the results are in the process of being published in a Special Issue of the Journal of Geochemical Exploration on Urban Geochemical Mapping, thus ending the first phase of the URGE project.

One of the results of the textbook and the urban geochemical surveys that were carried out in Europe is that the comparability between investigations and results from different European cities, the European overview, is missing. Thus, a second phase of the URGE project is in the process of being initiated. The suggested project aims at advising the city administration how such studies should be carried out, and how the data are best stored, evaluated and presented.  Furthermore, a directly comparable database shall be built for a number of European reference cities (N=15-25), participating in the proposed project.  For this purpose, a detailed manual for sampling topsoil in urban areas has been written (Demetriades and Birke, 2015a):

As there was a demand for a comprehensive Urban Geochemical Mapping Manual by the EU COST  Sub-Urban project (http://www.sub-urban.eu/), the EuroGeoSurveys’ Geochemistry Expert Group was commissioned to write it (Demetriades and Birke, 2015b) as part of WG 2.6 “Geochemistry” (http://sub-urban.squarespace.com/new-index-1/#geotechnical-modelling-hazards-wg-25):

former Director of the Division of Geochemistry and Environment,

Hellenic Institute of Geology and Mineral Exploration, Athens

References

Demetriades, A., Birke, M., 2015a.  Urban Topsoil Geochemical Mapping Manual (URGE II).  EuroGeoSurveys, Brussels, 52 pp., http://www.eurogeosurveys.org/wp-content/uploads/2015/06/EGS_Urban_Topsoil_Geochemical_Mapping_Manual_URGE_II_HR_version.pdf.

Demetriades, A., Birke, M., 2015b.  Urban Geochemical Mapping Manual:  Sampling, Sample preparation, Laboratory analysis, Quality control check, Statistical processing and Map plotting.  EuroGeoSurveys, Brussels, 162 pp., http://www.eurogeosurveys.org/wp-content/uploads/2015/10/Urban_Geochemical_Mapping_Manual.pdf.

Johnson, C.C., Demetriades, A., Locutura, J., Ottesen, R.T. (Editors), 2011.  Mapping the chemical environment of urban areas.  Wiley-Blackwell, John Wiley & Sons Ltd., Chichester, U.K., 616 pp., http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0470747242.html.

United Nations, 2014.  World Urbanization Prospects:  The 2014 Revision, Highlights (ST/ESA/SER.A/352). United Nations, Department of Economic and Social Affairs, Population Division, New York, 32 pp., http://esa.un.org/unpd/wup/Highlights/WUP2014-Highlights.pdf

As there was a demand for a comprehensive Urban Geochemical Mapping Manual by the EU COST  Sub-Urban project (http://www.sub-urban.eu/), the EuroGeoSurveys’ Geochemistry Expert Group was commissioned to write it (Demetriades and Birke, 2015b) as part of WG 2.6 “Geochemistry” (http://sub-urban.squarespace.com/new-index-1/#geotechnical-modelling-hazards-wg-25):

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### Abstract

Mangroves are often converted into gei wai ponds for aquaculture, but how such conversion affects the accumulation and behavior of heavy metals in sediments is not clear. The present study aims to quantify the concentration and speciation of heavy metals in sediments in different habitats, including gei wai pond, mangrove marsh dominated by Avicennia marina and bare mudflat, in a mangrove nature reserve in South China. The results showed that gei wai pond acidified the sediment and reduced its electronic conductivity and total organic carbon (TOC) when compared to A. marina marsh and mudflat. The concentrations of Cd, Cu, Zn and Pb at all sediment depths in gei wai pond were lower than the other habitats, indicating gei wai pond reduced the fertility and the ability to retain heavy metals in sediment. Gei wai pond sediment also had a lower heavy metal pollution problem according to multiple evaluation methods, including potential ecological risk coefficient, potential ecological risk index, geo-accumulation index, mean PEL quotients, pollution load index, mean ERM quotients and total toxic unit. Heavy metal speciation analysis showed that gei wai pond increased the transfer of the immobilized fraction of Cd and Cr to the mobilized one. According to the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) analysis, the conversion of mangroves into gei wai pond reduced values of ([SEM] − [AVS])/f oc , and the role of TOC in alleviating heavy metal toxicity in sediment. This study demonstrated the conversion of mangrove marsh into gei wai pond not only reduced the ecological purification capacity on heavy metal contamination, but also enhanced the transfer of heavy metals from gei wai pond sediment to nearby habitats.

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### Abstract

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