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Fledging Critical Zone Science for Environmental Sustainability Yihe Lü,*,†,‡ Ting Li,†,§ Kun Zhang,†,§ and Bojie Fu†,‡ †
State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China ‡ Joint Center for Global Change Studies, Beijing 100875, China § University of Chinese Academy of Sciences, Beijing 100049, China interactions among physical, chemical and biological processes from the atmosphere, biosphere, pedosphere, hydrosphere, and lithosphere. How to address these complex interactions using systematic monitoring and modeling remains a huge challenge in advancing CZS.4 Efforts to overcome this challenge are necessary for advancing CZS and pave the way for technological innovations targeting environmental sustainability. First, it is necessary to incorporate an extended multidimensional CZ concept for environmental sustainability. The original CZ concept defined CZ as a biophysical and geophysical entity and put much emphasis on its vertical dimension spatially and its temporal dimension from an evolutional perspective.3 However, the horizontal spatial dimension and the dimension of socioeconomics are also key for understanding the categorical and regional differentiations (Figure 1) of the Earth’s surface environment as well as the affiliated human−biophysical environmental interactions that have often been the root causes of many environmental problems, including ecological degradation and pollution. Even the cornerstone task of establishing CZ observatories and optimizing their global networks3 can be guided by the n the Anthropocene, humans face increasing challenges of understanding of geographical differentiations of earth surface sustainability from local to global scales. Responding to these systems for priority site selection. More specifically, human challenges, the United Nations released 17 sustainable activities and environmental impacts may transcend the former development goals and their related 169 targets up to 20301 defined boundary of the CZ both horizontally and vertically. with the key objective of protecting our planet and the longVertically, more and more people live and work in high term strong sustainability of coupled human and natural buildings well above the vegetation canopy in an urbanizing systems. Environmental sustainability is a fundamental world. Processes and their regulation in ambient environment, component of this key objective. However, environmental such as climate and air pollution, still need more scientific science has not yet developed to the point of significantly understanding of the lower atmosphere above the vegetation 2 facilitating environmental sustainability. Incorporating new canopy. Horizontally, areas without canopy cover (e.g., scientific developments in earth science may strengthen the permanent snow or glacier, or shallow water covered wetland) capacity of environmental science to understand and solve real provide critical functionality on provisioning natural resources world problems that humans face. Critical zone science (CZS) and regulating environmental processes. is such a new field of earth system science (ESS). The United Second, environmental services need to be put into the States National Research Council (NRC) first defined the central research themes of CZS to fully represent the criticality critical zone (CZ) as the surface layer of the terrestrial of CZ for environmental sustainability and human well-being. environment from the top of the vegetation canopy down to The CZ is inherently multifunctional, as it sustains and the weathering zone or bottom of groundwater aquifer. The regulates the complex interactions among biophysical, geoNRC recommended CZS as a new research focus of ESS in the 3 chemical, and socioeconomic development processes. CZ 21st century. The criticality of the CZ stressed by the NRC lies environmental services are a subset of CZ functions that in the functionality of the CZ to sustain life and thus the wellprovide environmental goods (e.g., clean air, clean water, and being of the human society. However, this function-oriented important habitats conserved for wildlife and people), mitigate perspective has not been incorporated into contemporary environmental pollution and degradation, and contribute to researches and the most significant progress of CZS so far has been the establishment of CZ observatories and the relevant findings on the observatory scale CZ structure, evolution, and Received: May 24, 2017 processes.3 In fact, the function of the CZ depends on complex
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© XXXX American Chemical Society
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DOI: 10.1021/acs.est.7b02677 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
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Environmental Science & Technology
Figure 1. Importance of horizontal environmental heterogeneity for categorizing regional critical zone (CZ) as illustrated by the Yellow River basin of China covering about 752 thousand km2. The Yellow River basin originates in the west from the Qinghai-Tibet plateau (QTP) with mean elevation of over 4000 m above sea level; the Loess Plateau lies in the central with elevation between 1000 m and 2000 m above sea level; main agricultural areas and large cities locate in river valleys and flood plains. Therefore, at least three types of CZ observatories on headwater remote highlands, midstream semiarid Loess Plateau, and river valley urban−rural areas can be established respectively according to the above regional scale geographical differentiations for environmental monitoring and research.
links among the diversified quantification and modeling methods, researchers can gain deep understanding of the behaviors and environmental impacts of CZ change. Rational adaptions of humans to CZ change with the goal of environmental sustainability can also be informed by such improved modeling. Multidisciplinary and international collaborations will be a practical means to facilitate the above advanced research in CZS oriented by common environmental and human well-being interests. Such collaborations can be encouraged by international research projects such as the European Commission-funded SoilTrEC3 and the ChinaUnited Kingdom initiatives on CZS of ecologically vulnerable regions (the Loess Plateau in northern China and Karst region in southwest China) and urbanization.5
ecosystem health and the physical and mental health of humans. The classification and quantification of CZ environmental services are priorities for advancing environmental sustainability. Finally, societal scale deep coupling research (i.e., a synergistic approach from multidisciplinary and interdisciplinary perspectives to fully understand the coevolution of CZ structures and functions3) is fundamental to advancing CZS for the sustainability of the terrestrial environment where humans live. Despite the fact that the understanding of CZ evolution needs to know the geologic history over millions of years as recorded in CZ,3 we have to put more emphasis on human history scale spanning just thousands of years to reveal the source and evolution of environmental degradation and pollution problems. To find solutions for environmental problems and to build capacity for adapting to environmental change, it is crucial to focus on the temporal scales of societal decision-making up to decades at most to keep uncertainties at acceptable level and raise the probability of effective actions. At these temporal scales, CZS needs to strengthen the research on the mechanisms of coupling among different CZ components and CZ-human interactions as well as on the incurred environmental and human well-being implications. Spatially distributed and dynamic CZ environmental monitoring, data sharing, and simulation model building are basic steps for advancing CZS. Particularly for modeling the dynamics of coupled environment-human systems under CZS perspective, the key challenge to overcome is to appropriately integrate various quantification and simulation approaches3,4 into a network of smoothly connected methods rather than only model libraries to represent the fast processes (e.g., chemical, biological, and atmospheric, and anthropogenic) and slow processes (e.g., geologic and pedologic) in CZ. Via seamless
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Yihe Lü: 0000-0002-1427-1333 Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS
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REFERENCES
This work was funded by the National Natural Science Foundation of China (41571130083).
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DOI: 10.1021/acs.est.7b02677 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
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DOI: 10.1021/acs.est.7b02677 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
