Organic carbon export from the Icelandic glaciers: quantification, sources, and down-stream fluxes

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Glaciers are an important store of organic carbon (OC) with potential effects on the land-to-ocean carbon fluxes. Due to climate change these fluxes are expected to accelerate. The release of glacial OC has been quantified in several regions worldwide, but there is no comparable data available for Iceland, although the largest nonpolar ice cap of Europe is located there.To enhance the global prediction of glacial organic carbon export, this pilot project aims to quantify the export of glacial dissolved and particulate organic carbon (DOC, POC) of Icelandic glaciers for the first time and to establish new cooperation with Icelandic scientists for common future research projects.Thus, a total of 4 field campaign during different seasons will be carried out together with face-to-face meetings with the Icelandic scientists. At each field campaign ice samples of 23 glaciers of the ice caps Vatnajökull, Langjökull, Hofsjökull, Myrdalsjökull, and Snæfellsjökull will be taken to investigate the biogeochemical diversity of glacial organic matter and to calculate an average export of DOC and POC along with the annual mass balances. Further, water samples will be taken in proglacial streams to detect the release of OC at the glacier terminus and to investigate the downstream alteration of DOC at 6 rivers with different distances from the glacier terminus to the ocean ranging from 2 km to 130 km. The long-term impact of the rapid glacier retreat on a glacier-fed river ecosystem will be assessed by repeating and comparing the investigations on macroinvertebrates carried out in 1997 by Prof. Gíslason. At the same time, to develop a more time-saving and less invasive method for monitoring the future impact of the glacial retreat on the glacier-fed stream ecosystem, water samples will be taken for eDNA barcoding in this river section.Beside on-site measurement of electrical conductivity, water temperate, pH-value, oxygen, turbidity and chlorophyll α innovative lab devices will be applied (HPLC, DNA barcoding, Picarro, GC, TOC) to detect the composition of OC in ice and water samples (DOC, DIC, POC, optical properties (fluorescence, absorbance), nutrients (P-PO4, N-NO3, N-NO2, N-NH4), stable isotopes (18O, 2H), chlorophyll α, carbon dioxide and aquatic organisms.The application of parallel factor analysis modeling based on excitation emission matrices will advance the identification of sources of OC exported from the different glaciers. The spatial diversity of OC characteristics in the glacial ice and in the proglacial streams will be assessed using principal component analysis.The gained knowledge will contribute to an enhanced global prediction of glacial OC export and to a deeper understanding of glacial environments. For the early career applicants this project will lead to promising future collaborations focusing on the spatial and temporal aspects of carbon cycling and fluxes as well as the ecology of glacial environments with Icelandic scientists.