Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems

Michael E. McClain, Elizabeth W. Boyer, C. Lisa Dent, Sarah E. Gergel, Nancy Grimm, Peter M. Groffman, Stephen C. Hart, Judson W. Harvey, Carol A. Johnston, Emilio Mayorga, William H. McDowell, Gilles Pinay

Research output: Contribution to journalReview article

1372 Scopus citations


Rates and reactions of biogeochemical processes vary in space and time to produce both hot spots and hot moments of elemental cycling. We define biogeochemical hot spots as patches that show disproportionately high reaction rates relative to the surrounding matrix, whereas hot moments are defined as short periods of time that exhibit disproportionately high reaction rates relative to longer intervening time periods. As has been appreciated by ecologists for decades, hot spot and hot moment activity is often enhanced at terrestrial-aquatic interfaces. Using examples from the carbon (C) and nitrogen (N) cycles, we show that hot spots occur where hydrological flowpaths converge with substrates or other flowpaths containing complementary or missing reactants. Hot moments occur when episodic hydrological flowpaths reactivate and/or mobilize accumulated reactants. By focusing on the delivery of specific missing reactants via hydrologic flowpaths, we can forge a better mechanistic understanding of the factors that create hot spots and hot moments. Such a mechanistic understanding is necessary so that biogeochemical hot spots can be identified at broader spatiotemporal scales and factored into quantitative models. We specifically recommend that resource managers incorporate both natural and artificially created biogeochemical hot spots into their plans for water quality management. Finally, we emphasize the needs for further research to assess the potential importance of hot spot and hot moment phenomena in the cycling of different bioactive elements, improve our ability to predict their occurrence, assess their importance in landscape biogeochemistry, and evaluate their utility as tools for resource management.

Original languageEnglish (US)
Pages (from-to)301-312
Number of pages12
Issue number4
StatePublished - Jun 1 2003


  • Biogeochemical cycles
  • Carbon
  • Nitrogen
  • Spatial scale
  • Temporal scale
  • Water resources management

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Environmental Chemistry
  • Ecology

Fingerprint Dive into the research topics of 'Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems'. Together they form a unique fingerprint.

  • Cite this

    McClain, M. E., Boyer, E. W., Dent, C. L., Gergel, S. E., Grimm, N., Groffman, P. M., Hart, S. C., Harvey, J. W., Johnston, C. A., Mayorga, E., McDowell, W. H., & Pinay, G. (2003). Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems. Ecosystems, 6(4), 301-312.