Environmental monitoring of pollution at legacy mines in Greenland using portable X-ray Fluorescence Spectrometry (pXRF)

Abstract

As the world’s need for raw materials increases, more mines are planned to be established in the Arctic. The Arctic provides a unique and challenging environment for mining operations and introduces concerns for the potential spread of pollution. Arctic environmental conditions linked to wind- and waterborne pollution transport such as hydrology, precipitation, temperature, windspeed and wind direction vary markedly throughout the year and the environment is sensitive to anthropogenic influence. In Greenland, several legacy mines provide testimony to how pollution still affects the sensitive Arctic environment. These legacy mines serve as valuable study sites that can improve future predictions on environmental consequences of mining operations in Greenland and other areas in the Arctic. Environmental studies at legacy mine sites in Greenland have previously focused on the leaching of pollutants into the marine environment and little is known about the spatial distribution of pollution in the terrestrial environment at these sites. In the current study, we present preliminary data from an environmental survey at the Blyklippen legacy mine. Blyklippen was a lead and zinc mine in East Greenland that operated between 1956-1963. Mining operations caused substantial pollution of lead (Pb), zinc (Zn), and other heavy minerals such as cadmium (Cd), barium (Ba) and copper (Cu), still measurable today. The primary sources of pollution today are the tailings storage facility and remains of ore concentrate spills along the haul road and at the quay areas at the harbor. Pollution is dispersed from these sites into the surrounding environment by wind and water. The aim of the current study is to investigate and map the spatial distribution of heavy metals in the environment surrounding the Blyklippen legacy mine using both field measurements by portable X-Ray Fluorescence spectrometry (pXRF) on depth specific sediment samples at in situ conditions and laboratory measurements on freeze-dried samples to investigate the effect of soil moisture on the accuracy of the field screening. Field measurements were conducted using short measurement times of 5-10 seconds, whereas laboratory measurement times were 180 seconds. A total number of 995 discrete sediment samples were collected over 10 days at the Blyklippen mine site and surrounding area of Mestersvig from 178 sampling locations at depth intervals of 5 cm. Our results demonstrate the effectiveness of pXRF as a field measurement tool for identifying the spatial delineation of soil pollution by comparing in situ measurements against pre-defined natural background values for heavy metals such as Pb and Zn. Comparison between Pb and Zn concentrations measured in the field versus in the laboratory on freeze-dried samples showed a good agreement for mineral soils. On organic and/or wet samples, field concentrations were underestimated for some elements. Overall, the approach shows that a fast and cost-effective large-scale field survey at legacy mines is obtainable using pXRF, enabling an effective identification of pollution ‘hotspots’ directly in the field. In combination with geostatistical mapping, the approach can improve the overall accuracy of environmental monitoring and mapping of pollution with enhanced environmental protection at both legacy, recent and future mines.