Jordan F. Clark

Professor -Enviro. Studies and Earth Science
Professor - Enviro. Studies and Earth Science

Contact Phone

(805) 893-7838

Office Location

Webb Hall 2115


Geochemistry, Hydrologic Sciences, Tracer Hydrology and Environmental Geology

Faculty in Environmental Studies and Earth Sciences Departments


  • Ph.D., Columbia University


Dr. Jordan Clark's research is focused on understanding hydrological and geochemical interactions that occur near the earth's surface and the effects of external anthropogenic and climatic forcing on these interactions. He uses geochemical tracers (both trace solutes and isotopes) in his investigations of earth surface processes. During the last decade, isotope hydrology as a sub-field has matured significantly and can now be used to addresses a significant number of new problems relating to hydrology and near surface processes.

He believes it is important to work on fundamental aspects of regional environmental problems and I spend a considerable amount of time on this type of research. His graduate studies on the Hudson River and, more recently, his research on Aquifer Storage and Recovery in California and aspects of the study on natural marine hydrocarbon seepage are examples of this effort. The remainder of his research time is spent examining geochemical problems related to global cycles and climate change (both recent and glacial/interglacial). His research on the hydrochemistry of springs, paleo-proxy data stored in groundwater, and methane emissions from hydrocarbon seepage illustrate this effort. Although his work examines problems in different environments, it is united by a common set of questions: how do transport processes affect water chemistry and quality and what are the impacts of climate change and other anthropogenic forcing on water chemistry and flow.


Research interests lie in the general field of aqueous geochemistry and center on: 1)

  1. the transport of water and dissolved material in groundwater, surface waters, and the coastal ocean 
  2. how flow patterns affect water quality
  3. gas exchange across the air-water interface
  4. climate change during the last 30,000 yr

These questions are examined using experiments conducted by introducing chemical tracers into the water bodies, plus analysis of flow patterns, residence times, and mixing rates inferred from the distribution of natural and anthropogenic tracers.


Impact of natural marine hydrocarbon seeps on the regional environment and global methane cycle. Seeps Web Page:
Groundwater flow near Aquifer Storage and Recovery sites.  
Chemical evolution of the shallow groundwater.


Selected Publications:

TClark, J. F., Washburn, L.,  ornafius, J. S., and Luyendyk, B. P. (2000) Dissolved hydrocarbon flux from natural marine seeps to the southern California Bight. Journal of Geophysical Research, 105, 11,509-11,522. pdf file

Leifer, I., J. F. Clark, and R. F. Chen (2000) Modifications of the local environment by natural marine hydrocarbon seeps. Geophysical Research Letters, 27, 3711-3714. pdf file
Clark, J. F. and G. B. Hudson (2001) Tracing hydrothermal fluids in hypersaline Mono Lake using helium isotopes. Limnology and Oceanography, 46, 189-196. pdf file
Radamacher*, L. K., J. F. Clark, G. B. Hudson, D. C. Erman, and N. A. Erman (2001) Chemical evolution of shallow groundwater as recorded by springs, Sagehen basin, Nevada County California. Chemical Geology, 179, 37-51. pdf file
Boles, J. R., J. F. Clark, I. Leifer, L. Washburn (2002) Temporal variation in natural methane seep rate due to tides, Coal Oil Point area, California. Journal of Geophysical Research, 106, 27,077-27,086. pdf file
Clark, J. F., I. Leifer, L. Washburn, B. P. Luyendyk (2003) Compositional changes in natural gas bubble plumes: Observations from the Coal Oil Point Seep Field. Geo-Marine Letters, 23, 187-193.
Clark, J. F., G. B. Hudson, M. L. Davisson, G. Woodside, and R. Herndon (2004) Geochemical imaging of flow near an artificial recharge facility, Orange County, CA. Ground Water, 42, 167-174.
Rademacher*, L. K., J. F. Clark, D. W. Clow, G. B. Hudson (2005) Old groundwater influence on stream hydrochemistry and catchment response in a small Sierra Nevada catchment: Sagehen Creek, California. Water Resources Research, 41, W02004, doi:10.1029/2003WR002805.
Clark, J. F., G. B. Hudson, and D. Avisar (2005) Gas transport below artificial recharge ponds: Insights from dissolved noble gases and a dual gas (SF6 and 3He) tracer experiment. Environmental Science and Technology, 39, 3939-3945.
Cook, P. G., S. Lamontagne, D. Berhane, J. F. Clark (2006) Quantifying groundwater discharge to Cockburn River, southeastern Australia, using dissolved gas tracers 222Rn and SF6. Water Resources Research, 42, W10411, doi:10.1029/2006WR004921.
Leifer, I., B. P. Luyendyk, J. R. Boles, J. F. Clark (2006) Natural marine seepage blowout: Contribution to atmospheric methane. Global Biogeochemical Cycles, 20, GB3008 10.1029/2005GB002668.
Clark, J. F. and G. B. Hudson (2006) Excess air: A new tracer for artificially recharged surface water. In: Recharge Systems for Protecting and Enhancing Groundwater Resources, IHP-VI, Series on Groundwater No. 13, UNESCO, 342-347.
*Graduate Student

Other Signnificant Publications:
Clark, J. F., H. J. Simpson, R. F. Bopp, and B. Deck (1992) Geochemistry and loading history of phosphate and silicate in the Hudson estuary. Estuarine, Coastal and Shelf Science, 34: 213-233.
Stute, M., P. Schlosser, J. F. Clark, and W. S. Broecker (1992) Paleotemperatures in the southwestern United States derived from noble gas measurements in groundwater. Science, 256, 1000-1003.
Clark, J. F., R. Wanninkhof, P. Schlosser, H. J. Simpson (1994) Gas exchange in the tidal Hudson River using a dual tracer technique. Tellus, 46B, 274-285.
Clark, J. F., P. Schlosser, R. Wanninkhof, H. J. Simpson, W. S. F. Schuster, D. T. Ho (1995) Gas transfer velocities for SF6 and 3He in a small pond at low wind speeds. Geophysical Research Letters, 22, 93-97.
Clark, J. F., H. J. Simpson, R. F. Bopp, and B. Deck (1995) Dissolved oxygen in lower Hudson estuary: 1978-93. Journal of Environmental Engineering, ASCE., 121, 760-763. pdf file
Stute, M., M. Forster, H. Frischkorn, A. Serejo, J. F. Clark, P. Schlosser, W. S. Broecker, and G. Bonani (1995) 5°C cooling of tropical Brazil during the last glacial maximum. Science, 269, 379-383.
Clark, J. F., P. Schlosser, M. Stute, and H. J. Simpson (1996) SF6 - 3He tracer release experiment: A new method of determining longitudinal dispersion coefficients in large rivers. Environmental Science and Technology, 30, 1527-1532. pdf file
Clark, J. F., M. Stute, P. Schlosser, S. Drenkard, and G. Bonani (1997) An isotope study of the Floridan aquifer in Southeastern Georgia: Implications for groundwater flow and paleoclimate. Water Resources Research, 33, 281-289.
Macfarlane, P. A., Clark, J. F., Davisson, M. L., Hudson, G. B., and Whittemore, D. O. (2000) Late Quaternary ground water recharge in the central Great Plains from geochemical tracers in shallow ground water. Quaternary Research, 53, 167-174. pdf file
Quigley*, D. C., J. S. Hornafius, B. P. Luyendyk, R. D. Francis, J. F. Clark, and L. Washburn (1999) Decrease in natural marine hydrocarbon seepage near Coal Oil Point, California associated with offshore oil production. Geology, 27, 1047-1050. pdf file
Rademacher*, L. K., J. F. Clark, and G. B. Hudson (2002) Temporal changes in stable isotope composition of spring waters: Implications for recent changes in climate and atmospheric circulation, Geology, 20, 139-142. pdf file
Luyendyk, B. P., J. P. Kennett, and J. F. Clark (2005) Hypothesis for increased atmospheric methane input from hydrocarbon seeps on exposed continental shelves during glacial low sea level. Marine and Petroleum Geology, 22, 591-596.


ES/GEOL 168 River Mixing
ES/GEOL 169 Tracer Hydrology
ES/GEOL 170 Environmental Geology