Holuhraun lavafält, CO2 utsläpp till atmosfären och CO2 deponering genom silikatvittring : När går lavafältet i Holuhraun, Island från kolkälla till kolsänka?

Volcanic eruptions initially lead to an output of CO2 however through silicate weathering, basaltic lava fields may become carbon sinks. Basaltic lava is rich in silicate minerals and when the lava field interacts with CO2 and H2O, hydrolysis occurs, leading to CO2 being deposited into the oceans. Two proxy-based approaches were used to estimate weathering rates. One method was based on empirical river flux rates in northern Iceland and the other method was based on basaltic dissolution rates in a lab setting. The primary focus is to calculate the weathering rates, with a focus on Ca and Mg and determine the timescale for the lava field to go from a carbon source to a carbon sink. Using a satellite orthophoto from 2017, the surface area of the Holuhraun lava field which had its eruption 2014-2015 was estimated at 83.25 km2, with a specific surface area of 362.21 km2 based on its morphology. Dissolution rates were calculated to be 2.57 x 105 mol•km-2•yr -1 for the river fluxes and 7.22 x 106 mol•km-2•yr -1 for the basaltic glass. The estimated timeframe for Holuhraun lava field to transition from a carbon source to a carbon ranged from 56 to 168 years using the basaltic glass proxy, and from 1,576 to 4,727 years using the river flux proxy. Key factors influencing basalt weathering include temperature, pH, specific surface area, humic acids, and mineral composition. The potential of basaltic lava fields contributing to long-term CO2 sequestration depend on environmental conditions and mineral composition.