Dry deposition and heavy acid loading in the vicinity of Masaya Volcano, amajor sulfur and chlorine source in Nicaragua

Certain volcanoes constitute the world's largest sources of SO2, HCl, and H F emissions and contribute significantly to regional acid deposition. Howev er, the impact of volcanic acid emissions to nearby ecosystems remain poorl y documented. In this paper, the spatial pattern of acid dry depositions wa s monitored within 44 km;of Masaya Volcano, Nicaragua, with a network of su lfation plates. Measured SO2 deposition rates were < 2 - 791 mg m(-2) day(- 1) The plates also collected the dry deposition of HCl at rates of < 1 - 29 7 mg m-2 day(-1). A similar deposition velocity 1/d (gas transfer) of 1.6 /- 0.8 cm/s was calculated for SO2 and HCl above the plate surfaces. Quanti ties of SO2 and HCl deposited daily within the area surveyed amounted to 1. 5 x 10(8) g and 5.7 x 10(7) g, respectively, which correspond to about 10% of the total SO2 and HCl released by the volcano. These depositions may gen erate an equivalent hydrogen flux ranging from < 1 to 30 mg m(-2) day(-1). Our results demonstrate that volcano emissions can dramatically affect acid deposition downwind and in turn cause extreme acid loading of the local ec osystems. This study opens exciting prospects for investigating the sensivi ty of volcanic ash soils to acid inputs.