Project at a Glance

Title: Integrated soil processes studies at Emerald Lake watershed

Principal Investigator / Author(s): Brown, Aaron D

Contractor: Department of Soil and Environmental Science, UC Riverside

Contract Number: A5-204-32

Research Program Area: Ecosystem & Multimedia Effects

Topic Areas: Acid Deposition, Ecosystem Impacts


We have studied the physical, chemical, and biological properties and processes of subalpine soils of the Emerald Lake Watershed (EL W), Sequoia National Park. Soils cover about 20% of the surface area of the watershed but other surficial materials not mapped as soils may have soil-like properties of weathering, cation and anion retention. In general most EL W soils can be classified as Cryorthents or Cryumbrepts with slightly different properties. A depression in pH and alkalinity were observed in response to the 1987 snow- melt in soil solutions extracted from a Cryumbrept in the field. The same degree of response was not observed at four other sites. Weathering of soil minerals to release AI3 + is a major mechanism of rapid acid neutralization in soils. Cation exchange is also important in affecting solution base cation composition. Sulfate adsorption appears to maintain relatively constant sulfate concentrations in soil solutions and surface waters through the critical snowmelt period, but adsorption levels are near capacity. Nitrate uptake, denitrification and mineralization moderate soil solution and surface water N concentrations, particularly during the summer months. In general, subalpine Sierra Nevada soils have significant capacity for neutralization of acidic deposition. The fact that snowmelt can reduce Cryumbrept soil solution ANC to negative levels is an indication that the rates of neutralization processes may be exceeded even under present conditions.

For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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