Cloud water and precipitation chemistry in a tropical montane forest, Monteverde, Costa Rica

Cloud water, mist and precipitation samples were collected at two sites in a tropical montane forest (TMF), Monteverde, Costa Rica. Cloud water, mist and wind-driven (u greater than or equal to 2 m s(-1)) precipitation samples were collected with passive cloud water-type collectors, and precipitation at low windspeeds (u < 2 m(-2)) was sampled with a bulk precipitation-type collector. Concentrations of H+, NO3-, and NH4+ in cloud water were 132 +/- 150, 103 +/- 82, and 149 +/- 200 mu mol l(-1) (mean +/- 1 S.D., n = 15), respectively. Concentrations of NO3-, NH4+, Ca-2(+) and K+ in cloud water samples collected at the middle and end of the dry season, which corresponded to biomass burning activities in the region, were significantly greater when compared to those collected early in the dry season. The mean concentration of H+ in cloud water at Monteverde was lower, but concentrations of NO3- and NH4+ were within the range of those collected at a number of montane sites in North America (62-195 mu mol NO3- l(-1) and 74-184 mu mol NH4+ l(-1)). Ion concentrations in mist were 2-24 times greater than those in both categories of precipitation. Ion concentrations in both categories of precipitation were generally within the range of those reported in bulk precipitation from other tropical premontane and TMF sites. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.