IMPROVING WATERSHED UNDERSTANDING IN THE ARCTIC THROUGH A COMPARATIVE HYDROGEOCHEMICAL ANALYSIS OF ICELANDIC GLACIAL MELTWATER

A detailed hydrogeochemical assessment of Icelandic glacier meltwater variability was conducted based on different types of glaciers. The goal of this study is a comparative geochemical characterization of three different types of Iceland glacial systems, which was carried out from June 7, 2016 to June 9, 2016 in a total of 11 outlet glaciers draining from three different ice caps. A total of 25 grab samples were collected. The ice caps include the second largest one in Europe, Vatnajökull, Eyjafjallajökull, and Mýrdalsjökull, the latter two of which are volcanically active. The alkaline (pH 6.65-9.22) nature of surface meltwaters of Iceland indicate that they are characteristically well buffered. Total suspended solids (0-499 mg/L), alkalinity (9.07 to 191.66 mg/L), and dissolved oxygen (10.99-17.18 mg/L) are highly variable between the glaciers and indicate possible influences from the bedrock over which the meltwater is flowing and differential erosion. The glacial lagoon, Jökulsárlón, had the highest concentration of nitrates (29.3 to 32.76 mg/L), possibly from birds defecating into the lagoon, and high levels of bicarbonate, sodium, total dissolved solids, and specific conductivity, which may be from its close connection to the ocean, where the waters mix. The concentration of cations and anions in glacial meltwaters draining from Mýrdalsjökull are on the order of Ca > Na > Mg > K and HCO₃ > Cl > SO₄ > NO₃ > F; Vatnajökull Na > Ca > Mg > K and HCO₃ > NO₃ > Cl > SO₄> F; and Eyjafjallajökull Na > Ca > Mg > K and HCO₃ > Cl > SO₄> NO₃ > F, respectively. The glacial meltwater draining from Kvíárjökull glacial exhibits highest concentrations of heavy metals such as, Fe (~8.3 mg/L) and Si (20.19 – 23.06 mg/L). Collectively, these data provide the first baseline sampling event of a series of three sampling events that will capture the onset of the melting season, its peak, and the transition between the ablation and accumulation seasons for the glaciers under study and will be compared against future data to determine the seasonal and hydrogeologic influences on glacier meltwater in southern Iceland.