Clouds in southern Chile: An important source of nitrogen to nitrogen-limited ecosystems?

Rainwater collected from remote, southern Chile is reported to be some of the most dilute in the world and is estimated to result in the deposition of less than or equal to 1 kg ha(-1) yr(-1) of nitrogen to ecosystems. Rainwater, however, is only one form of atmospheric deposition. Cloudwater deposition and the deposition of particles and gases can result in significant atmospheric inputs to ecosystems. Here we report the first data on cloudwater chemistry from remote, southern Chile. Cloud samples were collected from 1987 to 1994 using active cloudwater collectors. Average cloudwater chemistry from remote, southern Chile was dominated by ions commonly associated with seawater [e.g., Ca2+, Mg2+, Na+, Cl-), but had surprisingly high concentrations of inorganic nitrogen (NH4+ (48.3) and NO3- (19.6 mu equiv/L)] as well. Relative to volume-weighted mean concentrations of rainwater from a nearby location, cloudwater ranged from 2 (H+) to 80 (NH4+) times more concentrated. Estimated nitrogen deposition via cloudwater suggests that clouds may be a very important source of nitrogen, especially for nitrogen-limited ecosystems in this region.