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: http://dx.doi.org/10.1016/j.scitotenv.2014.02.133

 

Dr. Ariadne Argyraki, Assistant Professor in Geochemistry, University of Athens (argyraki@geol.uoa.gr)

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

  • Fate and partitioning of heavy metals in soils from landfill sites in Cape Town, South Africa: a health risk approach to data interpretation 2019-06-14

    Abstract

    The fate and persistence of trace metals in soils and sludge from landfill sites are crucial in determining the hazard posed by landfill, techniques for their restoration and potential reuse purposes of landfill sites after closure and restoration. A modified European Community Bureau of Reference’s (BCR) sequential extraction procedure was applied for partitioning and evaluating the mobility and persistence of trace metals (As, Cd, Cr, Cu, Ni, Pb, Sb, Se, Zn) in soils from three landfill sites and sludge sample from Cape Town, South Africa. Inductively coupled plasma optical emission spectroscopy was used to analyze BCR extracts. The mobility sequence based on the BCR mobile fraction showed that Cu (74–87%), Pb (65–80%), Zn (59–82%) and Cd (55–66%) constituted the mobile metals in the soils from the three sites. The mobility of Cu, Zn and Ni (> 95%) was particularly high in the sludge sample, which showed significant enrichment compared to the soil samples. Geo-accumulation index (Igeo) and risk assessment code were used to further assess the environmental risk of the metals in the soils. Exposure to the soils and sludge did not pose any non-cancer risks to adult and children as the hazard quotient and hazard index values were all below the safe level of 1. The cancer risks from Cd, Cr and Ni require that remedial action be considered during closure and restoration of the landfill sites.

  • An investigation into the use of < 38 µm fraction as a proxy for < 10 µm road dust particles 2019-06-13

    Abstract

    It is well documented that a large portion of urban particulate matters is derived from road dust. Isolating particles of RD which are small enough to be inhaled, however, is a difficult process. In this study, it is shown for the first time that the < 38 µm fraction of road dust particles can be used as a proxy for road dust particles < 10 µm in bioaccessibility studies. This study probed similarities between the < 10 and < 38µm fractions of urban road dust to show that the larger of the two can be used for analysis for which larger sample masses are required, as is the case with in vitro analysis. Road dust, initially segregated to size < 38 µm using sieves, was again size segregated to < 10 µm using water deposition. Both the original < 38 µm and the separated < 10 µm fractions were then subject to single particle analysis by SEM–EDX and bulk analysis by ICP-OES for its elemental composition. Dissolution tests in artificial lysosomal fluid, representative of lung fluid, were carried out on both samples to determine % bioaccessibility of selected potentially harmful elements and thus probe similarities/differences in in vitro behaviour between the two fractions. The separation technique achieved 94.3% of particles < 10 µm in terms of number of particles (the original sample contained 90.4% as determined by SEM–EDX). Acid-soluble metal concentration results indicated differences between the samples. However, when manipulated to negate the input of Si, SEM–EDX data showed general similarities in metal concentrations. Dissolution testing results indicated similar behaviour between the two samples in a simulated biological fluid.

  • Degradation of petroleum hydrocarbons in unsaturated soil and effects on subsequent biodegradation by potassium permanganate 2019-06-13

    Abstract

    To date, the oxidation of petroleum hydrocarbons using permanganate has been investigated rarely. Only a few studies on the remediation of unsaturated soil using permanganate can be found in the literature. This is, to the best of our knowledge, the first study conducted using permanganate pretreatment to degrade petroleum hydrocarbons in unsaturated soil in combination with subsequent bioaugmentation. The pretreatment of diesel-contaminated unsaturated soil with 0.5-pore-volume (5%) potassium permanganate (PP) by solution pouring and foam spraying (with a surfactant) achieved the total petroleum hydrocarbon (TPH) removal efficiencies of 37% and 72.1%, respectively. The PP foam, when coupled with bioaugmentation foam, further degraded the TPH to a final concentration of 438 mg/kg (92.1% total reduction). The experiment was conducted without soil mixing or disturbance. The relatively high TPH removal efficiency achieved by the PP–bioaugmentation serial foam application may be attributed to an increase in soil pH caused by the PP and effective infiltration of the remediation agent by foaming. The applied PP foam increased the pH of the acidic soil, thus enhancing microbial activity. The first-order biodegradation rate after PP oxidation was calculated to be 0.068 d−1. Furthermore, 94% of the group of relatively persistent hydrocarbons (C18–C22) was removed by PP–bioaugmentation, as verified by chromatogram peaks. Some physicochemical parameters related to contaminant removal efficiency were also evaluated. The results reveal that PP can degrade soil TPH and significantly enhance the biodegradation rate in unsaturated diesel-contaminated soil when combined with bioaugmentation foam.