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Water from air: An overlooked source of moisture in arid and semiarid regions

September 8, 2015

Water drives the functioning of Earth’s arid and semiarid lands. Drylands can obtain water from sources other than precipitation, yet little is known about how non-rainfall water inputs influence dryland communities and their activity. In particular, water vapor adsorption – movement of atmospheric water vapor into soil when soil air is drier than the overlying air – likely occurs often in drylands, yet its effects on ecosystem processes are not known. By adding 18O-enriched water vapor to the atmosphere of a closed system, we documented the conversion of water vapor to soil liquid water across a temperature range typical of arid ecosystems. This phenomenon rapidly increased soil moisture and stimulated microbial carbon (C) cycling, and the flux of water vapor to soil had a stronger impact than temperature on microbial activity. In a semiarid grassland, we also observed that non-rainfall water inputs stimulated microbial activity and C cycling. Together these data suggest that, during rain-free periods, atmospheric moisture in drylands may significantly contribute to variation in soil water content, thereby influencing ecosystem processes. The simple physical process of adsorption of water vapor to soil particles, forming liquid water, represents an overlooked but potentially important contributor to C cycling in drylands.

Publication Year 2015
Title Water from air: An overlooked source of moisture in arid and semiarid regions
DOI 10.1038/srep13767
Authors Theresa McHugh, Ember M. Morrissey, Sasha C. Reed, Bruce A. Hungate, Egbert Schwartz
Publication Type Article
Publication Subtype Journal Article
Series Title Scientific Reports
Index ID 70168431
Record Source USGS Publications Warehouse
USGS Organization Southwest Biological Science Center