HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Connin, S. L. Articles by Virginia, R. A. Search for Related Content PubMed Articles by Connin, S. L. Articles by Virginia, R. A. Agricola Articles by Connin, S. L. Articles by Virginia, R. A.

Isotopic Study of Environmental Change from Disseminated Carbonate in Polygenetic Soils

Dep. of Earth Sciences

Ross A. Virginia

Environmental Studies Program, Dartmouth College, Hanover, NH 03755

* Corresponding author ( lachlan{at}sun1paztcn.wr.usgs.gov).

ABSTRACT

We evaluated the extent to which ¹³C and ¹⁸O values of disseminated carbonate preserve a signal of Holocene and modern vegetation changes in polygenetic soils of the Jornada Basin, New Mexico. Factors and processes influencing carbonate chemistry were constrained in a relict grassland community and recent mesquite [Prosopis glandulosa var. torreyana (L. Benson) M. Johnston] dunes, using ¹⁴C dates and ¹³C data of soil organic matter (SOM) as independent measures of site history. Total-profile carbonate contents ranged from 39 to 451 kg m^-2 due to local patterns of soil water infiltration and erosion. In grassland soils, ¹⁴C ages and ¹³C values of disseminated carbonate in A and B horizons were influenced by the presence of older detrital carbonate, reworked from surrounding surfaces. As a result, carbonate isotopes did not record mid-Holocene climate and vegetation changes, which were inferred from ¹³C values of coexisting SOM. Shrub expansion during the past century was recorded by changes in the ¹³C values of disseminated carbonate and SOM from mesquite dunes. Carbon-14 data and mass balance estimates indicated that at least 80% of the dune carbonate (in C horizons) has been isotopically altered by dissolution and recrystallization processes in <100 yr. The modern carbonate is apparently forming from soil waters composed of nearly equal amounts of summer and winter rainfall, as evidenced by carbonate ¹⁸O values. Our analyses indicate that disseminated carbonate can provide a meaningful environmental signal in polygenetic soils, when pedogenic contributions to isotopic variability are constrained.

Received for publication August 5, 1996.

This article has been cited by other articles:

				A. Serna-Perez, H. C. Monger, J. E. Herrick, and L. Murray Carbon Dioxide Emissions from Exhumed Petrocalcic Horizons Soil Sci. Soc. Am. J., March 29, 2006; 70(3): 795 - 805. [Abstract] [Full Text] [PDF]