A reservoir of nitrate beneath desert soils |
| |
Authors: | Walvoord Michelle A Phillips Fred M Stonestrom David A Evans R Dave Hartsough Peter C Newman Brent D Striegl Robert G |
| |
Institution: | U.S. Geological Survey, Lakewood, CO 80225, USA. walvoord@usgs.gov |
| |
Abstract: | A large reservoir of bioavailable nitrogen (up to approximately 10(4) kilograms of nitrogen per hectare, as nitrate) has been previously overlooked in studies of global nitrogen distribution. The reservoir has been accumulating in subsoil zones of arid regions throughout the Holocene. Consideration of the subsoil reservoir raises estimates of vadose-zone nitrogen inventories by 14 to 71% for warm deserts and arid shrublands worldwide and by 3 to 16% globally. Subsoil nitrate accumulation indicates long-term leaching from desert soils, impelling further evaluation of nutrient dynamics in xeric ecosystems. Evidence that subsoil accumulations are readily mobilized raises concern about groundwater contamination after land-use or climate change. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|