SEGH Articles

# Global dispersion of trace metals in South America

04 November 2014
Pre-Hispanic metallurgical activities released enough metals to be transported throughout the entire South American continent.

Our recent study of a peat bog in remote Tierra del Fuego and published in PLOS ONE revealed that a part of trace metals – namely copper, lead, antimony and tin – originating from pre-Hispanic metallurgical activities can be recorded in Southern South America. It highlights for the first time that although of relatively small scale, pre-Hispanic metallurgical activities released enough metals to be transported throughout the entire South American continent through favourable wind trajectories. We also found that recent coal, gold and oil rushes released substantial amounts of local lead in the Southern American atmosphere. The uniqueness of these finding connects a number of different fields of research (geochemistry, archaeology, geology, atmospheric sciences) and has many important implications for our understanding of ancient metallurgy, and its legacy on trace metal emission, transport and deposition. First, it provides a scientific answer to a series of observations and questions that have puzzled the archaeological community for decades: (i) how large were the metal exploration and processing in pre-Hispanic times (as only point sources or artefacts have been found); (ii) was there a continuum between the metallurgical activities from different civilizations; and (iii) how far were metallurgical by-products transported via the atmosphere, and how they impacted the environment. Second, our finding will lead to a general agreement that past atmospheric circulation had a secondary North to South wind trajectory, which is opposed to the actual Westerly wind system dominating in South America. This mechanism evidenced by our HYSPLIT modelling and the fact that pre-Hispanic metals were transported to Tierra del Fuego, directly connects the geological cycles of trace elements with past atmospheric dust cycles, wind circulation and climate.

Picture 1. A partial view of the Karukinka peat bog complexe. Photo Courtesy J-Y De Vleeschouwer

Picture 2. F. De Veeschouwer and colleagues open a peat core containing several thousands of years of information about past metal and dust deposition, climate and environment. Photo Courtesy G. Le Roux

Picture 3. Outcrop of the ancient coal mine “Mina Elena” in South Patagonia. Photo Courtesy G. Le Roux

To know more about our research in South America and in peatlands in general, connect to our project webpage and our facebook page.

F. De Vleeschouwer - SEGH Member and former SEGH 2013 Conference Chairman

Webpage: http://www.ecolab.omp.eu/profils/DE-VLEESCHOUWER_Francois

Reference:

De Vleeschouwer F, Vanneste H, Mauquoy D, Piotrowska N, Torrejon F, et al. (2014) Emissions from Pre-Hispanic Metallurgy in the South American Atmosphere. PLoS ONE 9(10): e111315. doi:10.1371/journal.pone.0111315

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## Science in theNews

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

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• 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.