Abstract
A number of characteristics of the Lake Hovsgol watershed, such as the lake`s location at the edge of the Central Asian continuous permafrost zone, provide a unique opportunity to evaluate possible anthropogenic impacts in this remote area in northern Mongolia. In this study, we compared stream solute concentrations in six sub-watersheds in the Lake Hovsgol watershed. Water samples were collected during the summer months between 2003 and 2005. Concentrations of Cl- ranged from 9.8 to 51.3 μmol/L; average nitrate concentrations were very low and ranged from undetectable to 1.1 μmol/L and average SO4(2-) concentration at sampling stations with minimal animal grazing ranged from 66 to 294 μmol/L. Average dissolved organic carbon (DOC) concentrations ranged from 642 to 1,180 μmol C/L. We did not find statistically significant differences in DOC concentrations among the six streams, although DOC concentrations tended to be higher in the two northernmost streams, possibly related to differences in the active layer above the permafrost. Dissolved organic nitrogen (DON) concentrations were correlated with DOC concentration, and followed the same spatial pattern as those for DOC. In streams in this remote watershed, total dissolved nitrogen was made up of mostly organic N, as has been found for other regions distant from anthropogenic N sources. Overall, these results suggest that future research on the dynamics of DOC and DON in this watershed will be especially insightful in helping to understand how changes in climate and land use patterns will affect transformations, retention, and export of dissolved organic matter within these sub-watersheds in the Lake Hovsgol region.