HR: 1340h
AN: H43D-0401    [Abstracts]
TI: Weathering in and Calcium Losses From Semi-Arid Agricultural Landscapes: Insight From Strontium Isotope Ratios
AU: * Suzuki, K
EM: ksuzuki1@mail.wsu.edu
AU: Keller, C
EM: ckkeller@wsu.edu
AU: Vervoort, J D
EM: vervoort@wsu.edu
AB: The strontium isotope ratio ($^{87}$Sr/$^{86}$Sr) has been used in a number of recent studies of calcium cycling in forested ecosystems. In this research $^{87}$Sr/$^{86}$Sr was used to investigate weathering and, specifically, seasonal variation of calcium loss in drainage from semi-arid, agricultural landscapes in the Palouse Region of Washington State, USA. The Palouse is dominated by rolling loess hills. The soils are silt-loam Mollisols and the predominant origin of the loess substrate is continental crust. Tile drains are widely used to improve drainage of lower-slope fields. $^{87}$Sr/$^{86}$Sr of tile drainage, soil water, stream water and precipitation water were measured by multiple-collector Inductively Coupled Plasma Mass Spectrometry. $^{87}$Sr/$^{86}$Sr of precipitation waters exhibited considerable variation (0.708 to 0.713). $^{87}$Sr/$^{86}$Sr of the other water samples ranged from 0.707 to 0.708. These values are not close to continental crust values (0.716) but are more similar to basalts (0.702 to 0.707). $^{87}$Sr/$^{86}$Sr of tile drainage appeared to be negatively correlated with discharge during the rainy season. Thus it appears that sources of dissolved calcium in drainage vary seasonally. Results of this work may help predict the soil-acidification effects of heavy loading of these systems with ammonia-N fertilizers.
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
DE: 1875 Unsaturated zone
DE: 1040 Isotopic composition/chemistry
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting