Permafrost thaw and climate warming may decrease the CO2, carbon, and metal concentration in peat soil waters of the Western Siberia Lowland

T V Raudina; S V Loiko; A Lim; R M Manasypov; L S Shirokova; G I Istigechev; D M Kuzmina; S P Kulizhsky; S N Vorobyev; O S Pokrovsky

doi:10.1016/j.scitotenv.2018.04.059

Permafrost thaw and climate warming may decrease the CO₂, carbon, and metal concentration in peat soil waters of the Western Siberia Lowland

Sci Total Environ. 2018 Sep 1:634:1004-1023. doi: 10.1016/j.scitotenv.2018.04.059. Epub 2018 Apr 11.

Authors

Affiliations

¹ BIO-GEO-CLIM Laboratory, Tomsk State University, Lenina av, 36 Tomsk, Russia.
² BIO-GEO-CLIM Laboratory, Tomsk State University, Lenina av, 36 Tomsk, Russia; N Laverov Federal Center for Integrated Arctic Research, Institute of Ecological Problems of the North, Russian Academy of Science, Arkhangelsk, Russia.
³ N Laverov Federal Center for Integrated Arctic Research, Institute of Ecological Problems of the North, Russian Academy of Science, Arkhangelsk, Russia; Geoscience and Environment Toulouse (GET), UMR 5563 CNRS University of Toulouse, 14 Avenue Edouard Belin, 31400 Toulouse, France.
⁴ Geoscience and Environment Toulouse (GET), UMR 5563 CNRS University of Toulouse, 14 Avenue Edouard Belin, 31400 Toulouse, France,. Electronic address: oleg.pokrovsky@get.omp.eu.

PMID: 29660859
DOI: 10.1016/j.scitotenv.2018.04.059

Abstract

Soil pore waters are a vital component of the ecosystem as they are efficient tracers of mineral weathering, plant litter leaching, and nutrient uptake by vegetation. In the permafrost environment, maximal hydraulic connectivity and element transport from soils to rivers and lakes occurs via supra-permafrost flow (i.e. water, gases, suspended matter, and solutes migration over the permafrost table). To assess possible consequences of permafrost thaw and climate warming on carbon and Green House gases (GHG) dynamics we used a "substituting space for time" approach in the largest frozen peatland of the world. We sampled stagnant supra-permafrost (active layer) waters in peat columns of western Siberia Lowland (WSL) across substantial gradients of climate (-4.0 to -9.1°C mean annual temperature, 360 to 600mm annual precipitation), active layer thickness (ALT) (>300 to 40cm), and permafrost coverage (sporadic, discontinuous and continuous). We analyzed CO₂, CH₄, dissolved carbon, and major and trace elements (TE) in 93 soil pit samples corresponding to several typical micro landscapes constituting the WSL territory (peat mounds, hollows, and permafrost subsidences and depressions). We expected a decrease in intensity of DOC and TE mobilization from soil and vegetation litter to the supra-permafrost water with increasing permafrost coverage, decreasing annual temperature and ALT along a latitudinal transect from 62.3°N to 67.4°N. However, a number of solutes (DOC, CO₂, alkaline earth metals, Si, trivalent and tetravalent hydrolysates, and micronutrients (Mn, Co, Ni, Cu, V, Mo) exhibited a northward increasing trend with highest concentrations within the continuous permafrost zone. Within the "substituting space for time" climate change scenario and northward shift of the permafrost boundary, our results suggest that CO₂, DOC, and many major and trace elements will decrease their concentration in soil supra-permafrost waters at the boundary between thaw and frozen layers. As a result, export of DOC and elements from peat soil to lakes and rivers of the WSL (and further to the Arctic Ocean) may decrease.

Keywords: Carbon dioxide; Climate warming; Methane; Peat; Permafrost table; River; Suprapermafrost flow.