Houser Principles and Dynamics of the Critical Zone

1. Auflage 2015
ISBN: 978-0-444-63412-2
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, Band Volume 19, 674 Seiten

Reihe: Developments in Earth Surface Processes

Principles and Dynamics of the Critical Zone is an invaluable resource for undergraduate and graduate courses and an essential tool for researchers developing cutting-edge proposals. It provides a process-based description of the Critical Zone, a place that The National Research Council (2001) defines as 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.' This text provides a summary of Critical Zone research and outcomes from the NSF funded Critical Zone Observatories, providing a process-based description of the Critical Zone in a wide range of environments with a specific focus on the important linkages that exist amongst the processes in each zone. This book will be useful to all scientists and students conducting research on the Critical Zone within and outside the Critical Zone Observatory Network, as well as scientists and students in the geosciences - atmosphere, geomorphology, geology and pedology. - The first text to address the principles and concepts of the Critical Zone - A comprehensive approach to the processes responsible for the development and structure of the Critical Zone in a number of environments - An essential tool for undergraduate and graduate students, and researchers developing cutting-edge proposals

Autoren/Hrsg.

Houser, Chris

Leseproben

Chapter 1

Introduction to the Critical Zone

John R. Giardino*

Chris Houser**
*    High Alpine and Arctic Research Program, Department of Geology and Geophysics and the Water Management and Hydrological Science Graduate Program, Texas A&M University, College Station, Texas, USA
**    Department of Geography, Department of Geology and Geophysics, Office of the Dean of Geosciences, Texas A&M University, College Station, Texas, USA

Abstract

The National Research Council (NRC, 2001, p. 2) defined the Critical Zone as “the heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air and living organisms regulate the natural habitat and determine availability of life sustaining resources.” From this original definition, many, now loosely worded, definitions have been crafted to define the limits of this zone as ranging from the top of the canopy layer down to the bottom of the aquifer, so that the Critical Zone includes all the upper zone of Earth sensu lato. The term Critical Zone, referring to this near-surface and surface zone, was first introduced by Gail Ashley in 1988 to recognize that soil connects the vegetation canopy to the soil; the soil connects to the weathered materials and the weathered materials connect to bedrock, and bedrock provides the connection to the aquifer. In recognition of the importance of this cause-and-effect relationship between previously unconnected spheres, the US National Science Foundation (NSF) established 10 Critical Zone Observatories (CZOs) supported by a national office. This was followed by the establishment of Soil Transformations in European Catchments (SoilTrEC) by the consortium of European Union members. Today there are 64 CZOs spread across the planet but within a narrow range of biophysical environments. The raison d’être of the Critical Zone network is driven by basic principles of science: all the research at each location is focused on asking fundamental integrated biophysical questions and collecting and building long-term data banks from a well-studied environment. In this respect, one of the most important applied aspects of the global CZO network will be the development of reliable data that will lead to enlightened policy and management of the geoscience base of Earth. The name “Critical Zone” has become a fashionable term, but very little, truly integrated work occurs at the CZOs, which we argue will only be possible if it recognized that the real thread that connects all the components of the Critical Zone is water. That said, we think the Critical Zone concept is still a step in the right direction to serve as a unifying principle for the geosciences and an opportunity for truly integrative research of the biophysical environment and the role of humans within that environment.

Keywords

Critical Zone

water

Critical Zone Observatories

regolith

soil

It ain’t what they call you, it's what you answer to.

W.C. Fields

1.1. Introduction

Pick up a newspaper or magazine. Turn on the television or radio and watch or listen to the news or typical talk show. All of these will have articles or programs that focus on global change and human-caused actions that focus on drought, floods, earthquakes, oil spills, hurricanes, tsunamis, forest fires, coastal erosion, landslides, avalanches, and pollution of air and water resources. The list can go on and on. Partly as a result of the impact of these events on humans and the environment, the Nation Research Council's (NRC) Committee on Basic Research Opportunities in the Earth Sciences, and the National Science Foundation (NSF) created the Critical Zone Observatory (CZO) program (NRC, 2001). Whereas the NRC conceptualized the term, the funding of the program fell on the shoulders of NSF.

In the Principles and Dynamics in the Critical Zone, we have assembled a group of authors to provide a broad-ranging approach to Critical Zone research that extends beyond the current CZOs. Each chapter has been written with the perspective of integrating the viewpoints from specific fields into an interdisciplinary view of the Critical Zone. Each chapter provides a view of a specific discipline or from a specific environment and the contributions it brings to Critical Zone research. As a first step in reading this volume, we begin by providing a succinct overview of the Critical Zone.

1.2. Brief history and background of the Critical Zone observation network and Critical Zone Observatories

In 2001, a panel of the US National Research Council (NRC, 2001) recommended an integrated study of the Critical Zone as one of the most compelling research areas in Earth sciences in the twenty-first century. They (NRC, 2001, p. 2) went on to define the Critical Zone as “… the heterogeneous, near surface environment in which complex interactions involving rock, soil, water, air and living organisms regulate the natural habitat and determine availability of life sustaining resources.” From this original definition, many, now loosely worded definitions have been crafted to define the limits of this zone as ranging from the top of the canopy layer down to the bottom of the aquifer (Fig. 1.1).

Figure 1.1The diagram illustrates the extent of the Critical Zone from the top of the canopy to the bottom of the aquifer.
The pathways, which act as linkages for flows of energy and mass between the various subsystems of Earth, are shown as gray arrows. Modified from NRC (2001, p. 36).

Fortunately, today these various refinements and rewordings of the definition of the Critical Zone have brought additional clarity. For example, groundwater has been constrained from all groundwater to “freely circulating fresh groundwater,” instead of groundwater sensu lato. Aquifers that contain deep connate brines and confined aquifers have also been excluded (White, 2012). In reading the original definition, it is unclear what environments were to be included, and in fact, if some had not been excluded. One was left to assume that any environment present on the surface of Earth was included, but that was not clear. White (2012) has provided clarity to the definition, so that it encompasses polar/arctic, alpine, and desert environments, but not coastal. Whereas still limited, we think this clarification of the broader definition of the term Critical Zone has a more meaningful application than originally penned.

The NRC was not the creator of the “Critical Zone” term. It has been around for a long time. Tsakalotos (1909) first introduced the term into the chemical literature to describe the binary mixture of two fluids and geologists have long used the term to refer to the complex geology of the Bushveld Complex in South Africa (Cameron, 1963). The precursor application of the term Critical Zone to this relatively thin zone of Earth was first suggested by Gail Ashley (1998). She noted that the term applied where the soil connects the vegetation canopy to the soil; the soil connects to the weathered materials, and the weathered materials connect to bedrock, and bedrock provides the connection to the aquifer.

Critical Zone is a term that brings attention to both the scientific community and the layperson, of the important, critical role of what this relatively thin zone plays in the existence of life on Earth. Latour (2014) provided an interesting view of the Critical Zone from a geopolitical point-of-view. He argued that the important contributions of CZOs and the data they produce are providing various types of consistent observations from selected locations on Earth. More importantly, the Critical Zone concept deconstructs the planet into much smaller components of the “living planet.” Using the Critical Zone concept that focuses on an individual location brings understanding to the public of the linkages between a single, garden parcel to a total watershed to the complete planet. He pointed out how important the concept of scale is for humans to understand and accept responsibility for stewardship of Earth. This idea has been pushed by environmental groups who have coined the phrase “Think globally – Act locally.”

The creation of the CZOs is not the first time NSF has been involved with major contributions that benefit society. In fact, several authors have suggested that it was the contribution of scientists and engineers that helped win World War II that ultimately lead to the establishment of NSF (Mazuzan, 1988; Bronk, 1975; Kleinman, 1995). Today NSF is the only federal agency solely dedicated to the support of fundamental research and education. Over the past few years, NSF has shifted their focus from funding strictly fundamental research to requiring researchers to expand fundamental research to include contributions to society and outreach. The CZOs is one outcome of this new, important focus at NSF.

It was not until 2003 that funding for Critical Zone research appeared. The initial step in creating CZOs began with the funding of The Weathering System Science Workshop. The main...