Quantitative analysis of the rate of geochemical weathering of sulfur (
S) from sedimentary rocks (
GeoS) was conducted using concentration (
Cs) and discharge (
Qs) data from the Tedori River and atmospheric deposition (
AtdepS) in the basin. First,
S fluxes were calculated using 16 years of
Cs and
Qs data. The annual average discharge of
S (
TotalS) was estimated at 8597
ton·year
-1 (117.3 kg·ha
-1·year
-1). Of this, 1331 ton·year
-1 was
AtdepS (18.2 kg·ha
-1·year
-1) and another 7266 ton·year
-1 was
GeoS (99.1 kg·ha
-1·year
-1). Monthly changes in
TotalS were investigated, which showed that
GeoS was highest in summer, because of the air temperature, while
AtdepS peaked in winter because of seasonal wind. Using
Qs and
AtdepS corrected for altitude,
TotalS,
AtdepS and
GeoS were estimated at six sites, and among these sites we found that the
TotalS per unit area values were random, depending on the site characteristics. In particular, the discharge from the Kuwajima site was remarkably high suggesting that the sedimentary rocks at this site had higher pyrite content than at the other sites. Finally, we also assessed the relationship between the characteristics of sedimentary rocks and
GeoS in a range of rivers in the Hokuriku Region, and found that there was a close relationship between concentrations of
SO42- greater than 10 mg·l
-1 and sedimentary rocks containing the pyrite group. In addition, we estimated that the influence of
GeoS was present when the concentration of
SO42- in river water was greater than 2
- 3 mg·l
-1 in the Hokuriku region.