Atmospheric, geological and geochemical influences on high mountain northern New Mexico lakes subjected to acidic deposition
Carl J. Popp, Thomas R. Lynch, Timothy J. Peter, and James M. Robertson

Abstract:

Acidic precipitation has been reported from many parts of the West, including New Mexico. High mountain watersheds may be especially vulnerable because their surficial rocks and soils often have low buffering capacity. A limnological and geological survey of 17 high elevation lakes was conducted in northern New Mexico. Data from five representative lake basins are reported herein. The relative contributions of precipitation and weathering to aqueous chemistry were also examined in one lake. Sedimentation ratios were determined using Cs-137 and Pb-210 geochronology. Lakes were typically small, shallow and colorless. Buffering capacity varied from 8 to 820 µeq/L and was directly related to the surficial geology. Atmospheric contributions to the chemistry of Santa Fe Lake are large in comparison to weathering inputs for all species except HCO3 and Si02. Half of the sulfate found in lake water originates from the atmosphere. Back-reacting the lake-water chemical  constituents attributable to geochemical weathering produced reasonable agreement with minerals present in the basin. Sedimentation rates in three of the five lakes varied from 7 to 13 mm/y. Profiles of Pb-210 in two lakes were anomalous. Sediment profiles of Cs- 137 were not representative of the fallout history and were therefore useless for age-dating purposes.


Citation:

  1. Popp, Carl J.; Lynch, Thomas R.; Peter, Timothy J.; Robertson, James M., 1990, Atmospheric, geological and geochemical influences on high mountain northern New Mexico lakes subjected to acidic deposition, in: Tectonic development of the southern Sangre de Cristo Mountains, New Mexico, Bauer, Paul W.; Lucas, Spencer G.; Mawer, Christopher K.; McIntosh, William C., New Mexico Geological Society, Guidebook, 41st Field Conference, pp. 439-444.

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