基于能值分析方法的城市代谢过程研究--理论与方法

Urban metabolism process based on emergy synthesis: Theory and method

作为一个以人类活动为中心的社会-经济-自然复合生态系统,城市所遵循的高投入、低产出、高污染的粗放型发展模式导致了严重的结构性隐患与环境问题。基于生物物理的视角考虑,城市生态环境问题的出现,与城市代谢不良密切相关。当前对城市代谢的研究视角多基于污染物排放和资源消费,需要一种热力学的全新视角从整体角度来重新诠释可持续发展。开发了一种基于能值分析方法的城市代谢过程研究框架,首先对城市的可持续发展进行热力学解析,其次针对现有能值方法的局限,结合自然系统对污染物的自净化及污染对经济系统和生态系统的损害程度测度方法,从水体污染、大气污染和固体废物研究城市代谢对人群健康和自然生态系统的影响。研究有利于解决城市代谢不良的影响因子识别问题和代谢系统综合评价问题,使政策制定者建立以生态为本的城市观,推动社会系统的生态化转型实践,力求突破当前城市发展的瓶颈,促进城市的可持续发展。

As the center of human activities and social civilization, city has developed at the cost of serious environmental degradation and huge eco-environmental pressure, which further lower the human living standard and impeded the sustainable development of the urban ecosystem. Current urban metabolic methods have broader views and focus more on ecological aspects--impact of emissions and resource consumption ― but they lack a rigorous thermodynamic framework. Consequently, there is a need for modifying existing processes and developing new technologies that minimize environmental impact while providing stimulating ecological flow. This study developed an emergy-based framework for evaluating ecological objectives in traditional urban metabolic process. It started with a brief historical review of urban sustainable development and examines the controversial concept critically from a thermodynamic point of view. Then the assessment framework was proposed by reviewing and compiling existing data and studies on environmental issues available primarily at some sources, which includes resource accounting and environmental impact assessment. The direct and indirect emergy demand was assessed and quantied based on airborne/waterborne pollutants dilution patterns, and concepts of Life Cycle Impact Assessment. Such a framework is a necessary pre-requisite to perform a reliable cost-benefit evaluation of urban sustainability strategies, and provide guidance to policy decisions.