SEGH Articles

# A pre-mining survey to establish the geochemical baseline in stream water and sediment of a mineralised area in north Greece

02 March 2012

One of the lessons learnt by the legacy of mining is that involvement of environmental scientists in the initial planning stages, in geochemistry baseline studies is significant for setting up realistic goals for monitoring and remediation programs.

A recent PhD project in the Department of Economic Geology and Geochemistry at the University of Athens, Greece investigated the geochemical characteristics of surface water and stream sediments of Asprolakkas drainage basin, an area of sulphide mineralization within metamorphic rocks, located in Chalkidiki peninsula, north Greece. One of the research objectives was to establish the geochemical baseline conditions prior to any type of new mining activity. The area represents the only example of active mining and processing of base metal sulphide ore in Greece and also includes an unmined porphyry Cu-Au ore deposit that will be exploited in the near future. In a wider context, this research represents a pre-mining baseline geochemical study that can be used as an analogue for similar metallogenetic provinces in areas with a Mediterranean type climate. The deposits of the area have a long exploitation history that started in 600 BC and continues until today, mainly because of their Au potential. It is believed that the mining activity in Chalkidiki during ancient times was the major source of gold during the era of Fillip II and Alexander the Great.

Concentrations of dissolved major ions and trace metals displayed wide variability within the study area. Kokkinolakkas, the stream draining the exploited Pb-Zn (±Ag) ore bodies, is strongly influenced by chemical weathering of sulphide minerals and presents elevated levels of SO4, Pb, Zn, Mn, Ni, Cd, As and Sb. Stream water of the unmined areas demonstrated a different chemical composition with elevated values mainly for Pb and As. It was found that hydrological conditions are important in modeling the element concentrations in water under present conditions. Major ion content decreases in the wet period as a result of dilution owing to the heavy winter rainfall. A contrasting behavior was observed for heavy metal composition in Kokkinolakkas water samples, due to the enhanced base metal dissolution under high run off conditions. It appears that downstream dispersion of metals is favoured by transport via adsorption processes onto very fine particles (< 0.45 μm). The study also revealed that weathering of the mineral deposits supports the occurrence of a prevalent Fe-Mn oxyhydroxide surface, which is considered to be capable of scavenging toxic metals. However, these precipitates could be a secondary source of trace metals for the water column upon dissolution of the oxides under reduced conditions. Cadmium is the only labile metal indicating the different chemical binding, and higher solubility of this element, compared to the other heavy metals. High actual concentrations were also measured in the carbonate fraction of Kokkinolakkas stream sediment samples, highlighting that pH is the principal variable governing the potential release of these elements to the dissolved phase.

Bearing in mind the ongoing mining developments in the area, results of this study are very significant, providing scientific data about the present environmental-geochemical baseline conditions of the drainage basin and are available for any future comparison. These data can enable mine planners to better anticipate and plan for potential environmental impacts and are useful for setting up realistic goals in monitoring and remediation programs.

Dr Ariadne Argyraki, Assistant Professor in Geochemistry, National and Kapodistrian University of Athens. E-mail: argyraki@geol.uoa.gr

Stream water sampling in Chalkidiki, Greece.

Reference

Kelepertzis, E., Argyraki, A., Daftsis, E (2012). Geochemical signature of surface water and stream sediments of a mineralized drainage basin at NE Chalkidiki, Greece: A pre-mining survey, Journal of Geochemical Exploration, 114, 70-81. (doi:10.1016/j.gexplo.2011.12.006)

Keep up to date

## 34th SEGH International Conference: Geochemistry for Sustainable Development

Victoria Falls, Zambia

02 July 2018

## SubmitContent

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

## Science in theNews

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

• Fertilizer usage and cadmium in soils, crops and food 2018-06-23

### Abstract

Phosphate fertilizers were first implicated by Schroeder and Balassa (Science 140(3568):819–820, 1963) for increasing the Cd concentration in cultivated soils and crops. This suggestion has become a part of the accepted paradigm on soil toxicity. Consequently, stringent fertilizer control programs to monitor Cd have been launched. Attempts to link Cd toxicity and fertilizers to chronic diseases, sometimes with good evidence, but mostly on less certain data are frequent. A re-assessment of this “accepted” paradigm is timely, given the larger body of data available today. The data show that both the input and output of Cd per hectare from fertilizers are negligibly small compared to the total amount of Cd/hectare usually present in the soil itself. Calculations based on current agricultural practices are used to show that it will take centuries to double the ambient soil Cd level, even after neglecting leaching and other removal effects. The concern of long-term agriculture should be the depletion of available phosphate fertilizers, rather than the negligible contamination of the soil by trace metals from fertilizer inputs. This conclusion is confirmed by showing that the claimed correlations between fertilizer input and Cd accumulation in crops are not robust. Alternative scenarios that explain the data are presented. Thus, soil acidulation on fertilizer loading and the effect of Mg, Zn and F ions contained in fertilizers are considered using recent $$\hbox {Cd}^{2+}$$ , $$\hbox {Mg}^{2+}$$ and $$\hbox {F}^-$$ ion-association theories. The protective role of ions like Zn, Se, Fe is emphasized, and the question of Cd toxicity in the presence of other ions is considered. These help to clarify difficulties in the standard point of view. This analysis does not modify the accepted views on Cd contamination by airborne delivery, smoking, and industrial activity, or algal blooms caused by phosphates.

• Effects of conversion of mangroves into gei wai ponds on accumulation, speciation and risk of heavy metals in intertidal sediments 2018-06-23

### 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.

• Cytotoxicity induced by the mixture components of nickel and poly aromatic hydrocarbons 2018-06-22

### Abstract

Although particulate matter (PM) is composed of various chemicals, investigations regarding the toxicity that results from mixing the substances in PM are insufficient. In this study, the effects of low levels of three PAHs (benz[a]anthracene, benzo[a]pyrene, and dibenz[a,h]anthracene) on Ni toxicity were investigated to assess the combined effect of Ni–PAHs on the environment. We compared the difference in cell mortality and total glutathione (tGSH) reduction between single Ni and Ni–PAHs co-exposure using A549 (human alveolar carcinoma). In addition, we measured the change in Ni solubility in chloroform that was triggered by PAHs to confirm the existence of cation–π interactions between Ni and PAHs. In the single Ni exposure, the dose–response curve of cell mortality and tGSH reduction were very similar, indicating that cell death was mediated by the oxidative stress. However, 10 μM PAHs induced a depleted tGSH reduction compared to single Ni without a change in cell mortality. The solubility of Ni in chloroform was greatly enhanced by the addition of benz[a]anthracene, which demonstrates the cation–π interactions between Ni and PAHs. Ni–PAH complexes can change the toxicity mechanisms of Ni from oxidative stress to others due to the reduction of Ni2+ bioavailability and the accumulation of Ni–PAH complexes on cell membranes. The abundant PAHs contained in PM have strong potential to interact with metals, which can affect the toxicity of the metal. Therefore, the mixture toxicity and interactions between diverse metals and PAHs in PM should be investigated in the future.