SEGH Articles

Urban soil of Athens, Greece: Local geology beats human pollution on trace elements

04 June 2014
Bearing in mind the historical absence of heavy industry within the Greater Athens and Piraeus area, the tested hypotheses was that local geology is important in controlling the distribution of potentially harmful trace elements in urban soil.

Bearing in mind the historical absence of heavy industry within the Greater Athens and Piraeus area, the tested hypotheses was that local geology is important in controlling the distribution of potentially harmful trace elements in urban soil.


The first geochemical baseline study of surface soil in Athens, based on a systematic sampling survey covering the Greater Athens and Piraeus area, was recently performed by the Laboratory of Economic Geology and Geochemistry, University of Athens. In the study, the contents of the major elements Fe, Al, K and Ca, and potentially harmful elements Ni, Cr, Co, Mn, As, Pb, Zn, Cu, Cd, Sb and Sn were determined.

Athens, Greece is a European city with a very long history. The area has been continuously inhabited for more than 7,000 years and provides an example of early urbanization in the ancient world. However, unlike most European capitals, the urbanization of modern Athens was not related to the Industrial Revolution. The city experienced rapid population growth from ~400,000 people in 1925 to > 1,000,000 by 1950.  The population increase of modern Athens is marked by the return of Greek refugees from Asia Minor in the 1920s after World War I, and extensive internal migration after World War II. Today, the urban area of Greater Athens and Piraeus has a population of ~ 3.2 million over an area of 412 km2. This constitutes ~ 1/3rd of the Greek population. In addition, this area is the center of economic and commercial activities for the country.

Principle Component Analysis and Cluster Analysis, combined with analysis of soil heterogeneity and spatial variability, were implemented in order to distinguish the sources of elements and their classification as geogenic or anthropogenic. It was found that the major factor controlling variability of the chemical composition of surface soil was the bedrock chemistry, resulting in a significant enrichment in concentrations of Ni, Cr, Co and possibly As. Greek soil is naturally enriched in Cr, Ni, Co and Mn as a result of the widespread occurrence of basic and ultrabasic rocks. Furthermore, elevated As concentrations in soil and natural waters have been linked to metamorphic rocks in Greece.

Anthropogenic influences were also significant, controlling a spectrum of elements that are typical of human activities, i.e. Pb, Zn, Cu, Cd, Sb, and Sn. The highest concentrations of the classical urban contaminants were observed in the surface soil from roadside verges and in the older parts of the city, as well as the densely populated areas. Spatial distribution patterns of PHEs demonstrated an increase in concentrations of the anthropogenically induced metals towards the city core and the port of Piraeus. On the contrary, the naturally derived Ni, Cr and Co are mainly enriched in the periphery of Athens Basin.


Taking into account the salient enrichment of geogenic PHEs in Athens soil, comparing with concentrations measured in other cities around the world, this study provides base for further research into PHE mobility and bioaccessibility. This work is also important for under the current economic conditions the development of urban agriculture is an emerging initiative of several municipalities. The results of the study are presented in a publication in the Science of the Total Environment:


Dr. Ariadne Argyraki, Assistant Professor in Geochemistry, University of Athens (

Keep up to date

Submit Content

Members can keep in touch with their colleagues through short news and events articles of interest to the SEGH community.

Science in the News

Latest on-line papers from the SEGH journal: Environmental Geochemistry and Health

  • Geophagy among East African Chimpanzees: consumed soils provide protection from plant secondary compounds and bioavailable iron 2019-12-01


    Geophagy, the intentional consumption of earth materials, has been recorded in humans and other animals. It has been hypothesized that geophagy is an adaptive behavior, and that clay minerals commonly found in eaten soil can provide protection from toxins and/or supplement micronutrients. To test these hypotheses, we monitored chimpanzee geophagy using camera traps in four permanent sites at the Budongo Forest Reserve, Uganda, from October 2015–October 2016. We also collected plants, and soil chimpanzees were observed eating. We analyzed 10 plant and 45 soil samples to characterize geophagic behavior and geophagic soil and determine (1) whether micronutrients are available from the soil under physiological conditions and if iron is bioavailable, (2) the concentration of phenolic compounds in plants, and (3) if consumed soils are able to adsorb these phenolics. Chimpanzees ate soil and drank clay-infused water containing 1:1 and 2:1 clay minerals and > 30% sand. Under physiological conditions, the soils released calcium, iron, and magnesium. In vitro Caco-2 experiments found that five times more iron was bioavailable from three of four soil samples found at the base of trees. Plant samples contained approximately 60 μg/mg gallic acid equivalent. Soil from one site contained 10 times more 2:1 clay minerals, which were better at removing phenolics present in their diet. We suggest that geophagy may provide bioavailable iron and protection from phenolics, which have increased in plants over the last 20 years. In summary, geophagy within the Sonso community is multifunctional and may be an important self-medicative behavior.

  • Accumulation of uranium and heavy metals in the soil–plant system in Xiazhuang uranium ore field, Guangdong Province, China 2019-12-01


    Plants that have grown for many years in the special environmental conditions prevailing in mining areas are naturally screened and show strong capacity to adapt to their environment. The present study investigated the enrichment characteristics of U and other heavy metals (As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni) in the soil–plant system in Xiazhuang uranium mine. Four dominant plants (Castanopsis carlesii, Rhus chinensis, Liriodendron chinense, and Sapium discolor) and soil samples were collected from the mined areas, unmined areas, and background areas away from the ore field. U, As, Cu, Pb, Mn, Mo, Zn, Cd, Co, and Ni concentrations were analyzed by ICP-MS. The results demonstrate that (1) The highest concentrations of U (4.1–206.9 mg/kg) and Pb (43.3–126.0 mg/kg) with the geoaccumulation index (Igeo) greater than 1 show that they are the main soil pollutants in the research area. (2) The biological accumulation coefficient (LBAC) values for Cd, Mn, and Cu are greater than zero in S. discolor, L. chinense, and C. carlesii and these three plants indicate that they can be used for remediation of the soil in the ore field. (3) R. chinensis inhibits the accumulation of heavy metals and shows sensitive pigment responses to the accumulation of U in the leaves. L. chinense has the strongest enrichment effect on heavy metals but exhibits weak biochemical responses under U stress. C. carlesii demonstrates strong adaptation to U and can maintain healthy pigment characteristics in case of high U enrichment. (4) S. discolor, L. chinense, C. carlesii and R. chinensis have strong tolerance to U toxicity and different biochemical responses.

  • Distribution, sources and health risk assessment of contaminations in water of urban park: A case study in Northeast China 2019-12-01


    This case study was performed to determine whether the pollutants in water of urban park could bring health risk to human engaging in water-related activities such as swimming and provide evidence demonstrating the critical need for strengthened recreational water resources management of urban park. TN, NH4+-N, TP, Cu, Mn, Zn, Se, Pb, As, Cd and Cr(VI) contents were determined to describe the spatial distribution of contaminations; sources apportionment with the method of correlation analysis, factor analysis and cluster analysis were followed by health risk assessment for swimmers of different age groups. The results reveal that element contents in all sites do not exceed Chinese standard for swimming area and European Commission standard for surface water; all detected elements except Cr(VI) have a tendency to accumulate in the location of lake crossing bridge; Mn and Zn are considered to have the same pollution source including geogenic and anthropogenic sources by multivariable analysis. Carcinogenic risks of different age groups descend in the same order with non-carcinogenic risks. Among all elements, Zn and Mn contribute the lowest non-carcinogenic risk (5.1940E-06) and the highest non-carcinogenic risk (7.9921E-04) through skin contact pathway, respectively. The total average personal risk for swimmers in swimming area is 1.9693E-03, and this site is not suitable for swimming. Overall, it is possible that swimmers are exposed to risk via the dermal route when carrying out water-related activities, it is recommended that necessary precautions and management should be taken in other similar locations around the world.