DANIEL OBRIST

Associate Research Professor
Division of Atmospheric Sciences

PROFESSIONAL INTERESTS:

My research interests include atmospheric chemistry, transport, and biogeochemistry of pollutants and quantification of surface exchange processes of atmospheric constituents between soils, plants, and the atmosphere.  A special emphasis includes cycling of mercury in the environment and how global change and disturbances affect these processes. Current research projects include (i) systematic quantification of mercury loads in forest across the United States to assess atmospheric loadings sequestered in terrestrial systems; (ii) study of biogeochemical processes of mercury sequestered in soils and litter to assess it’s fate during organic carbon decomposition; (iii) assessment of long-range transport of atmospheric pollutants (e.g., Asian pollution events) and tropospheric oxidation of mercury at DRI’s high-elevation research Station, Storm Peak Laboratory in the Rocky Mountains; (iv) development of a novel real-time sensor based on Cavity-Ring-Down spectroscopy to measure atmospheric mercury concentrations; and (v) study of mercury depletion events in the halogen-rich atmosphere at the Dead Sea, Israel to determine oxidation pathways and kinetics for mercury oxidation in temperate areas. Other interests include effects of wildfires and global change (e.g., elevated CO2, increasing tropospheric ozone) on hydrology and carbon and nutrient cycling processes in terrestrial ecosystems.

PROJECT WEBSITES:

• MRI: Development of a Cavity Ring-Down Sensor for Real-Time Measurement of Atmospheric Mercury Concentrations and Fluxes
• Mercury Oxidation and Depletion in the Reactive Halogen Enriched Troposphere of the Dead Sea
• Effects of Global Change on the Atmospheric Mercury Burden and Mercury Sequestration Through Changes in Ecosystem Carbon Pools
• Air-snow exchanges and snow chemistry in alpine and polar areas
• Long-range transport of Mercury from Asia to the Western United States
• Mass-balance approach to quantify watershed-scale mercury fluxes in the Sierra Nevada

SELECTED PUBLICATIONS:

Faïn, X., Obrist, D., Hallar, A.G., McCubbin, I., and Rahn, T., (2009).

High levels of reactive gaseous mercury observed at a high elevation research laboratory in the Rocky Mountains, Atmos. Chem. Phys. Discuss., 9, 15641-15671.

Cheng X, Luo Y, Su B, Verburg P, Hui D, Obrist D, Arnone JA, Johnson DW, Evans RD (2009).

Responses of net ecosystem CO2 exchange to nitrogen fertilization in experimentally manipulated grassland ecosystems. Agricultural and Forest Meteorology, in press.

Obrist D, Johnson DW, Lindberg SE (2009).

Mercury concentrations and pools in four Sierra Nevada forest sites, and relationships to organic carbon and nitrogen. Biogeosciences, 6, 1-13.

Fritsche J, Wohlfahrt G, Ammann C, Zeeman M, Hammerle A, Obrist D, Alewell C (2008).

Summertime elemental mercury exchange of temperate montane grasslands on an ecosystem-scale. Atmos. Chem. and Physics, 8, 7709-7722.

Obrist D, Hallar AG, McCubbin I, Stephens BB, Rahn T (2008).

Measurements of atmospheric mercury at Storm Peak Laboratory in the Rocky Mountains: Evidence for long-range transport from Asia, boundary layer contributions, and plant mercury uptake. Atmos. Environ., 42, 7579-7589.

Fritsche J, Obrist D, Zeeman MJ, Conen F, Eugster W, Alewell C (2008).

Elemental mercury fluxes over a sub-alpine grassland in Switzerland determined with two micrometeorological methods. Atmos. Environ., 42, 2922-2933.

Fritsche J, Obrist D, Alewell C (2008).

Effects of microbiological activity on Hg0 emission in uncontaminated terrestrial soils. Plant Nutrition and Soil Science, 171, 200-209.

Obrist D, Moosmüller H, Schürmann R, Chen A, Kreidenweis S (2008).

Particulate-phase and gaseous elemental mercury emissions during biomass combustion: controlling factors and correlation with particulate matter emissions. Environ. Sci. and Techol., 42, 721-727.

Li W, Collins JF, Durbin TD, Huai T, Ayala A, Full G, Mazzoleni C, Nussbaum NJ, Obrist D, Zhu D, Kuhns HD, Moosmüller H (2007).

Detection of Gasoline Vehicles with Gross PM Emissions. SAE Tech. Pap. Ser., SP-2089, 2007-01-1113.

Peleg M, Matveev V, Tas E, Luria M, Valente RJ, Obrist D (2007).

Mercury depletion events in the troposphere in Mid-Latitudes at the Dead Sea, Israel. Environ. Sci. and Technol., 41, 7280-7285

Faïn X, Grangeon S, Bahlmann E, Fritsche J, Obrist D, Dommergue A, Ferrari CP, Cairns W, Ebinghaus R, Barbante C, Cescon P, Boutron C (2007).

Diurnal production of Gaseous Mercury in the alpine snowpack before snowmelt. J. Geophys. Res. – Atmos., 112, D21311.

Obrist D (2007).

Atmospheric mercury pollution due to losses of carbon pools? Biogeochemistry 85, 119-123.

Millhollen AG, Gustin MS, Obrist D (2006).

Foliar mercury accumulation and exchange for three tree species.  Environ. Sci. and Technol., 40, 6001-6006.

Millhollen AG, Obrist D, Gustin MS (2006).

Mercury accumulation in grass and forb species as a function of atmospheric carbon dioxide concentrations and mercury. Chemosphere, 65, 889-897.

Obrist D, Conen F, Vogt R, Siegwolf R, Alewell C (2006).

Quantification of elemental Hg0 exchange using 222Rn/Hg0 accumulation in the stable nocturnal boundary layer. Atmos. Environ., 40, 856-866.

Prater MR, Obrist D, Arnone JA, DeLucia EH (2006).

Net carbon exchange and evapotranspiration in postfire and intact sagebrush communities in the Great Basin.  Oecologia, 146, 595-607.

Obrist D, Gustin MS, Arnone JA, Schorran DE, Verburg PSJ, Johnson DW (2005).

Measurements of gaseous elemental mercury fluxes over intact tallgrass prairie monoliths during one full year.  Atmos. Environ., 39, 957-965.

Obrist D, Yakir, D, Arnone JA III (2004).

Temporal and spatial patterns of soil water following wildfire-induced changes in plant communities in the Great Basin.  Plant and Soil, 262, 1-12.

Verburg PS, Arnone JA, Obrist D, Schorran DE, Evans D, LeRoux-Swarthout D, Johnson D, Luo Y, Coleman JS (2004). 

Net ecosystem carbon exchange in two experimental grassland ecosystems.  Global Change Biology, 10, 498-508.

Obrist D, Verburg PSJ, Young MH, Coleman JS, Schorran DE, Arnone JA (2003).

Quantifying the effects of phenology on ecosystem evapotranspiration in planted grassland mesocosms using EcoCELL technology.  Agricultural and Forest Meteorology, 118,173-183.

Obrist D, DeLucia EH, Arnone JA (2003).

Consequences of wildfire on ecosystem CO2 and water vapor fluxes in the Great Basin. Global Change Biology, 9, 563-574.

Arnone JA, Obrist D (2003).

A large daylight geodesic dome for quantification of whole ecosystem CO2 and water vapor fluxes in arid ecosystems. J. Arid Environ., 55, 629-643.

Obrist D, Arnone JA (2003).

Root development, soil water use, and root proliferation into resource-rich soil patches of Larrea tridentata under past, ambient, and future atmospheric CO2 levels. New Phytologist, 159, 175-184.

Obrist D, Arnone JA, Körner Ch (2001).

In situ effects of elevated atmospheric CO2 on leaf freezing resistance and carbohydrates in a native temperate grassland. Annals of Botany, 87(6), 839-844.