[H-TT31] New development of environmental traceability methods

[HTT31-P04] Estimation of sulfur dynamics in a small forest catchment by isotopic ratio analysis

*Tatsuyoshi SAITO¹, Naoyuki YAMASHITA¹, Yayoi INOMATA¹, Shigeki UCHIYAMA², Makoto NAKATA³, Tsuyoshi OHIZUMI¹, Hiroyuki SASE¹ (1.Asia Center for Air Pollution Research, 2.Environmental Science Research Niigata, 3.Faculty of Agriculture, Niigata University)

Keywords:sulphur isotopic ratio, rainfall, stream water, soil water

This study is conducted to clarify the dynamics of sulphur derived from atmospheric deposition, by sulphur isotopic analysis.
The study plot was selected in a small catchment of a Japanese ceder forest in Kajikawa, Niigata prefecture, Japan which suffered large amount of deposition from transboundary air pollution. Rainfall, stream water and soil solution were collected from the study site at least once a month. In addition, throughfall and stemflow were also collected. Sulphur isotopic ratio(δ³⁴S) and also water chemicals in these samples were determined.
Seasonal variation of δ³⁴S from Aug. 2012 to Aug. 2013 is shown in Figure. Clear variation is shown in rainfall, but δ³⁴S in stream water is stable at 9‰. It suggests that sulphur in rainfall does not directly reach to stream. Sulphur deposition may be retained once in ecosystem and δ³⁴S changed by some processes for example soil adsorption. We’ll discuss about the data include throughfall, stemflow and soil solutions in presentation.
The study was supported by the grant from APN (ARCP2013-13CMY-Sase). Authors thank them for their support and cooperation.