We have obtained new data on the chemical composition (including trace elements) and discharge of the Golubye Ozera ultra acid boiling springs which emit water on the southwestern slope of Baransky Volcano, Iturup Island. It is shown that the cation composition corresponds to solution of 1 g host rock and 1 L water. We carried out hydrologic and hydrochemical measurements to find the total hydrothermal release of magmatic volatiles Сl and S (in the form SO4) along the beds of the main streams that drain the solfataric fields and springs of Baransky Volcano (Kipyashchy Creek and Sernaya River) and estimated the chemical erosion affecting the volcanic edifice. The total measured hydrothermal discharge of Cl and SO4 into the Pacific Ocean reaches 14 t/d and 41 t/d, respectively. The mixed chemical erosion affecting the volcanic deposits in the Sernaya R. basin is about 150 t/km2/yr. The contribution of Kipyashchy Creek into the discharge of dissolved rock-forming components is above 30% of total discharge into the Pacific Ocean on the part of the Sernaya River.