Award Date

5-1995

Degree Type

Thesis

Degree Name

Master of Science in Geoscience

Department

Geoscience

First Committee Member

Neil L. Ingraham, Chair

Second Committee Member

John W. Hess

Third Committee Member

David L. Weide

Graduate Faculty Representative

Stanley D. Smith

Number of Pages

144

Abstract

Precipitation, vapor water, ground water, soil water, grape berry and grape leaf water, grape must, and vintage wines were collected from northern California for stable isotopic analysis. An understanding of factors controlling isotopic ratios of wine allows evaluation of wine as a surrogate of past precipitation. Stable isotopic compositions of grape berry waters collected at Charles Krug Winery in Napa Valley. CA range from -31 to -17 per mil in 8D and +7.2 to +15.3 per mil in 8180, and plot along a transpiration line of slope 2. 7. Grape leaf waters range from -25 to +5 per mil in 8D and +0.9 to +12.4 per mil in 8180, and plot along a transpiration line of slope 2.1. Isotopic compositions of wine range from -3 to +20 per mil in 1\D and +4.6 to +10.2 per mil in 8180 and plot along a "wine line" of slope 3.5. Similar samples collected from Concannon Vineyard in Livermore Valley, CA show similar variations as those from Napa Valley, CA.

Grape berry and grape leaf waters are up to 59 per mil in 8D and 18 per mil in 8180 more enriched than soil water. Grape leaf water was more responsive to pre-harvest precipitation, shifting 15 per mil in 8D and 8.1 per mil in 8180, than grape berries which showed a delayed shift of 13 per mil in 8D and 4.6 per mil in 8180.

Yearly variations in isotopic values for wines produced in Napa Valley in the last 30 years range from 0 to 13 per mil in 8D and 0.1 to 4.8 per mil in o180. Variations average 6 per mil in oD and 1. 7 per mil in o180 between each consecutive year. Strong correlations are observed between isotopic ratios of wine and temperature (0.94). relative humidity (·0.93), and ET (0.93) for approximately 1-3 months prior to harvest. The correlation with annual precipitation (0.30) suggests that amount of rainfall has nominal affect on stable isotopic ratios of wine. And the correlation observed between compositions of wine and wine quality (0.43) has no practical predictive capabilities.

Wines do not provide sufficient information for annual weather data In verification of climate models. Nevertheless. variations in stable isotopic ratios of wine represent changes in weather conditions during the growing season.

Keywords

Climate; Climatic changes; Isotope geology; Water chemistry; Wine — Composition; Wine and wine making — Temperature

Disciplines

Climate | Geology | Hydrology

Language

English

Comments

(Refer to PDF file for exact formulas.)


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