Importance of Permafrost Wetlands as Dissolved Iron Source for Rivers in
the Amur-Mid Basin
Y. Tashiro1,2*, M. Yoh3, V. P.
Shesterkin4 , T. Shiraiwa5, T.
Onishi6, D. Naito7,8*
1United Graduate School of Agricultural Science, Tokyo
University of Agriculture and Technology, Tokyo 1838509, Japan,2Institute for Space–Earth Environmental Research,
Nagoya University, Aichi 4648601, Japan, 3Emeritus
professor, Institute of Agriculture, Tokyo University of Agriculture and
Technology, Tokyo 1838509, Japan, 4Khabarovsk Federal
Research Center of the Far Eastern Branch of the Russian Academy of
Sciences, Institute of Water and Ecology Problems (FEB RAS), Khabarovsk
680000, Russia, 5Institute of Low Temperature Science,
Hokkaido University, Hokkaido 0600819, Japan, 6Faculty
of Applied Biological Sciences, Gifu University, Gifu 5011193, Japan,7Center for International Forestry Research (CIFOR),
Bogor 16115, Indonesia, 8Faculty/Graduate School of
Agriculture, Kyoto University, Kyoto 6068502, Japan
*Current Affiliation
Corresponding author: Yuto Tashiro
(tassy40y@gmail.com)
Key Points:
- We provide a landcover classification method with high resolution of
30m using Landsat-8 data and machine learning (decision tree
analysis).
- Three normalized indices (for vegetation, soil, and water) and slope
enabled us to identify the distribution of permafrost wetland.
- Riverine dissolved iron concentrations in the watersheds showed a
clear positive correlation with the coverages of permafrost wetland.
Abstract
Dissolved iron (dFe) transported by the Amur River greatly contributes
to phytoplankton growth in the Sea of Okhotsk. Nevertheless, there has
been little research on the dFe source of rivers, especially in the
Amur-Mid Basin which is situated in a sporadic permafrost area. In the
Amur-Mid Basin, permafrost generally exists under wetlands in the flat
valley, and these permafrost wetlands could be a dFe source of rivers.
To asess the importance of the permafrost wetlands as a dFe source,
first we made a landcover map with high resolution of 30 m using
Landsat-8 data and a machine learning technique (decision tree
analysis). As a result of decision tree analysis, three normalized
indices (normalized diference vegetation index, normalized difference
soil index, and normalized difference water index) and slope enabled us
to classify landcovers into three vegetation types: wetland, forest, and
grassland. Using this landcover map, we investigated the coverages of
the permafrost wetland in the sampled watersheds and examined the
correlation with river water chemistry (dFe, dissolved organice carbon:
DOC, and electrical conductivity: EC). As a result, dFe and DOC
concentrations showed a clear positive correlation (dFe:r2 = 0.66, DOC: r2 =
0.46) with the coverage of permafrost wetlands, while EC showed a
negative correlation with those (r2 = 0.45).
These findings are the first to demonstrate the direct evidence about
the importance of permafrost wetlands to supply dFe and DOC to rivers in
the Amur-Mid Basin.