Earth's Critical Zone

The Earth's Critical Zone is the “heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air, and living organisms regulate the natural habitat and determine the availability of life-sustaining resources” (NRC, 2001).

The Critical Zone includes the land surface, vegetation, and water bodies, and extends through the pedosphere, unsaturated vadose zone, and saturated groundwater zone. The critical zone is the most heterogeneous portion of the Earth. An array of important physical, chemical, and biological interfacial processes and reactions occur in the critical zone over a range of spatial and temporal scales. These processes impact mass and energy exchange necessary for biomass productivity, chemical recycling, and water storage. They also control transport and cycling of contaminants including organics, metals, and radionuclides.

History

In late August 2003, a group of Scientists submitted a funding request to the National Science Foundation and following approval of this request, the first Weathering System Science Workshop convened in Baltimore, MD (October 2003). The organizing committee for this workshop included Susan Brantley, Oliver Chadwick, Louis Derry, Lee Kump and Art White.

Participants agreed to promote subsequent outreach activities to broaden the cross section of involved Earth scientists and crafted a set of questions that would drive further development of Weathering System Science. This field of science was considered to include all aspects of chemistry, biology, physics, and geology of the Critical Zone.

The Weather System Science Consortium was established in early 2004 and later was changed to the [http://www.czen.org Critical Zone Exploration Network] (CZEN) in 2006.

In October 2005 WSSC/CZEN solicitated a call for proposals to initiate seed sites that would help grow and establish a critical zone network. [http://www.czen.org/CZENsites 8 sites] were awarded grants.

In 2005 the University of Delaware hosted an NSF-sponsored workshop ( [http://ag.udel.edu/plsc/Conference/ Frontiers in Exploration of the Critical Zone] ) that resulted in a call by scientists for an international initiative to study the critical zone. As key parts of that initiative, the scientists called for the development of an international Critical Zone initiative and a systematic approach to the investigation of processes in the critical zone across a broad array of sciences, including geology, soil science, biology, ecology, chemistry, geochemistry, geomorphology and hydrology. A booklet ( [http://www.czen.org/booklet Frontiers in Exploration of the Critical Zone] ) was produced from the meeting.

On July 24, 2006 NSF posted a solicitation for proposals for [http://www.nsf.gov/funding/pgm_summ.jsp?pims_id=500044&org=NSF&sel_org=NSF&from=fund Critical Zone Observatories] (CZO) with in the Division of Earth Sciences. The Awards have not yet been announced.

Established in 2007, the University of Delaware Center for Critical Zone Research [http://ag.udel.edu/plsc/CenterforCriticalZone.htm] is a multidisciplinary initiative bringing together scientists, engineers and policy specialists across the university to focus on basic research of the Earth’s critical zone. The Center will develop strong partnerships with government agencies (local, state, and federal), industry and the public. A key goal of the Center is to integrate science, ethics, and public policy.

A Fall 2007 workshop discussed the ongoing collection and compilation of data for CZEN.

Related Sites

The Critical Zone Exploration Network [http://www.czen.org]
Delaware EPSCoR Science [http://www.epscor.dbi.udel.edu/outreach/science/article.php?id=9]
University of Delaware Center for Critical Zone Research [http://ag.udel.edu/plsc/CenterforCriticalZone.htm]