State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
J Environ Manage. 2022 Sep 1;317:115371. doi: 10.1016/j.jenvman.2022.115371. Epub 2022 May 23.
The metabolic processes of cities and their embedded regions have received great attention, but it is still unclear how the metabolic processes change at the scale from cities to urban agglomerations. In view of the lack of multi-scale research in the field of urban metabolism, this study took Beijing-Tianjin-Hebei region, one of the urban agglomerations with largest economic scales in China, as a case to construct metabolic network models at two scales of city and urban agglomeration. The material transfers between nodes were calculated, and the connection degree index was put forward in the ecological network analysis to quantify the influence of a single node on the network when multi-level transfers were considered. On this basis, the similarities and differences of metabolic nodes at the two scales were analyzed. The results showed that nearly 97% of the volume of material transfers in the urban agglomeration was concentrated within the cities, among which the transfer volumes of Tangshan, Handan, and Shijiazhuang were more than 600 Mt. Manufacturing and environment were the major contributors to material transfers. The connection degrees of nodes had both commonness and differences at the two scales. In general, the connection degrees at the urban scale were relatively homogeneous, while their difference was large at the urban agglomeration scale. The connection degrees of nodes in Langfang were prominent at the urban agglomeration scale. The connection degrees of environment and manufacturing ranked top 3 at both scales. Meanwhile, the connection degree of energy conversion at the urban scale was relatively high, while its influence was replaced by mining sector at the urban agglomeration scale. The analysis of material metabolic nodes in Beijing-Tianjin-Hebei region can provide theoretical supports to position the key points in the process of material utilization in the cities or the urban agglomeration, and help to identify the breakthrough points for subsequent regulatory.
城市及其嵌入区域的代谢过程受到了广泛关注，但城市代谢过程在城市到城市群的尺度上如何变化仍不清楚。鉴于城市代谢领域缺乏多尺度研究，本研究以中国经济规模最大的城市群之一——京津冀地区为例，构建了城市和城市群两个尺度的代谢网络模型。计算了节点之间的物质转移量，并在生态网络分析中提出了连接度指数，以量化在考虑多层次转移时单个节点对网络的影响。在此基础上，分析了两个尺度上代谢节点的异同。结果表明，城市群中近 97%的物质转移量集中在城市内部，其中唐山、邯郸和石家庄的转移量超过 600Mt。制造业和环境是物质转移的主要贡献者。节点的连接度在两个尺度上既有共性又有差异。一般来说，城市尺度上的连接度相对均匀，而城市群尺度上的差异较大。在城市群尺度上，廊坊的节点连接度较为突出。环境和制造业的连接度在两个尺度上均排名前 3 位。同时，城市尺度上的能源转换连接度相对较高，而在城市群尺度上则被采矿业所取代。对京津冀地区物质代谢节点的分析可以为确定城市或城市群物质利用过程中的关键点提供理论支持，并有助于识别后续调控的突破点。
