Urban street dusts play a key role in human exposure pathways to metals, especially in cities impacted by active and legacy mining (like Copiapó, an arid Chilean city).  They also record the recent history of metal accumulation from natural and human sources.  While some studies have assessed the occurrence of metals in street dusts, not much is known yet about their spatial and temporal response to city-wide episodic perturbations, like floods and landslides.  We studied the dynamics of metals in street dust before (November 2014), the same year (October 2015, 7 months after), and after a mudslide in Copiapó (December 2016) (29 samples). Major and trace elements (arsenic, calcium, cobalt, copper, iron, manganese, lead, zinc) were analyzed by X-ray fluorescence in samples previously dried and sieved to 2 mm. Concentrations of copper and lead (in mg/kg, mean value in brackets) ranged between 111-10,224 (900) and &lt;22-224 (56) in 2014; 80-4,789 (352) and &lt;22 (0% quantification) in 2015; and 67-5,811 (471) and &lt;22-144 (33) in 2016, respectively. Differences in concentration (p&lt;0.05) were not statistically significant for: manganese 2014-2015; arsenic, calcium, cooper and zinc 2015-2016; and arsenic 2014-2016, suggesting a disruptive effect of the mudslide in the spatial and temporal distribution of the other elements measured. Furthermore, the mean concentration of all elements (except for manganese) was lower in 2015, suggesting an attenuation effect that reverted over time (arsenic, copper, lead, and zinc increased from 2015 to 2016). Additionally, the mean values were generally greater than the geochemical background calculated for the area, suggesting enrichment due to anthropogenic activities (mining and tailings). Moreover, all copper concentrations exceeded Canadian recommendations for residential soils, indicating a potential health risk to the population. Further research is needed in order to understand the effect of natural and anthropogenic events on urban geochemistry, feeding critical information to public policies towards environmental and human health protection in mining cities.

Dynamics of metals in street dust after a mudslide: Case of mining city in Chile

2019 Fall National Meeting

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