Imagine Greenland, an environment synonymous with being untouched by humans and severe climate or think about Iceland – where more than one- tenths of the land is covered by ice and population density is smaller than in any other European country. Both countries are resourced with significant amounts of fresh water which is polluted to a negligible degree. This makes drinking only tap water quite common among their inhabitants. That sounds reasonable, as it reduces costs and is environmentally friendly. However there is a hidden danger. My research has shown that the tap water in Iceland may be too clean to provide vital nutrients found in tap water elsewhere.
To exemplify a typical bottle of mineral water may contain about 240 mg/L of Ca2+ and 120 mg/L of Mg2+. Quantity of that water necessary to achieve the normal daily intake of calcium and magnesium cations (not considering other sources) is about 3 liters. In comparison, drinking only Greenland tap water, the amount would be 360 liters per day, so 12 times more.
How do I know that? While staying in Tasiilaq (Southeastern Greenland) and Reykjavik (the capital of Iceland) I have taken tap water samples and tested them using atomic absorption spectroscopy (AAS). The main advantage of AAS is the determination of the overall concentration of the particular metal in a sample. It does not matter whether the metal is bound within a compound or is just an ion. This is because the liquid sample is heated or transferred to a graphite tube to be atomised and then ionised. The absorbed energy is than emitted and measured. Other benefits of using AAS are high selectivity and uncomplicated sample preparation, which really counts when we have to transport it tucked away in luggage to a different continent.
The concentration of calcium and magnesium in tap water from Tasiilaq and Reykjavik is low – in both samples it does not exceed 2.5 mg/L, but levels of other tested metals – cobalt, copper, iron and zinc were even under limit of detection (less than 1 mg/L for iron and 0.1 mg/L for others). European Economic Area norms for tap water are approximately 20 times higher than ones measured in water from Greenland and Iceland. Moreover, considering the influence of such an insignificant content of macro elements we have to include two more factors – diet and subarctic climate.
Especially in Greenland, in towns stricken by poverty, diet lacks in vegetables and fruit, as they have to be transported from Denmark. For instance, prices of vegetables rich in magnesium in the only ‘supermarket’ in Tasiilaq are higher than in the centre of London or other European cities.
Nevertheless, all of these metals are supplied within our everyday food and drinks. The research did not involve medical tests or sufficient number of samples. At that level, my study is pointing out the need of further tests than stating clearly the problem.
About the author:
Dominika Łącała is a final class student at the John III Sobieski Secondary School in Kraków, currently applying to study Chemistry in England. She conducted her research at the University of Technology and Science, Kraków. Her main area of interest is analytical chemistry, especially atomic absorption spectroscopy and voltammetry. In her free time she enjoys travelling to frosty places, caring for animals and studying other sciences.