Improving carbon emission efficiency (CEE) is a necessary consideration in response to economic downturn and climate change. In this case, industrial symbiosis paves the way for cities to conserve energy, reduce carbon emissions, and upgrade economic development patterns. This paper verifies the influence of industrial symbiosis policies on CEE, represented by National Demonstration Eco-industrial Parks (NDEPs). The difference-in-differences (DID) and spatial DID (SDID) models, as well as panel data of 282 Chinese cities during 2003–2019, were used to complete this argumentation process. The results show that NDEP policy dramatically increases the CEE of pilot cities. Compared with cities without NDEP, pilot cities climb by 3.49% on CEE, mainly due to industrial structure upgrading and green technological innovation. Moreover, eastern, non-resource-based, and multi-NDEP cities experience a noticeable increase in CEE. NDEP increases not only the CEE of pilot cities but also that of their neighboring cities within 450 km through diffusion and demonstration effects. All these findings help promote China’s NDEP construction and offer decision-making guidance for climate governance and low-carbon transition in China and others following a similar pathway.

In the initial stage, the epidemic area is relatively concentrated, and some traffic modes may be subject to traffic control. In this period, the timely delivery of adequate emergency medical supplies to the epidemic points will play an important role in controlling the spread of the epidemic. However, the existing emergency medical supplies loading optimization model has not taken the initial period of the epidemic as the research time nor fully considered the traffic control situation in that period. Therefore, combined with the characteristics of the initial epidemic period of COVID-19, this study establishes an optimization model for emergency medical supplies stowage at the rescue point, considering the variation in demand for different kinds of medical supplies at the epidemic point in different cycles and the impact of traffic control on the mode of transportation. The model is an integer programming model. The objective function is the least total cost, including total transportation cost and total inventory cost. The constraints include the supply limit of each medical material that can be provided by the rescue point, the transportation capacity limit of the transportation mode, the demand constraints, inventory constraints, nonnegative constraints, and integer variable constraints of various medical supplies in each cycle of the epidemic location. Finally, combining the development of the epidemic situation in Wuhan January 18–23, 2020, a case study was carried out, and the optimal combination of different transportation modes and different stowage schemes in different periods of the rescue point was obtained, which verified the feasibility and practicality of the model. The model constructed in this study can provide a theoretical reference to the optimal decision-making plan of emergency medical supplies of the implementation of traffic control during the initial period of emergency public health events.

Under the new water control philosophy, reclaimed water utilization is an important strategic measure to increase water supply and reduce water environmental pollution. This has important implications for addressing the water crisis in urban development. The scientific and reasonable price of reclaimed water has a positive effect on promoting the utilization of reclaimed water and improving the utilization rate of urban reclaimed water. Therefore, this study extracted the influencing factors of reclaimed water price through grounded theory and used the ISM method to elucidate the logical hierarchy and investigate their influencing mechanisms. The results indicate that the structural system of factors affecting the price of reclaimed water was composed of 16 factors, which could be divided into four hierarchical levels. Among them, the external value of reclaimed water utilization, the technical level of reclaimed water processes, the regional economic development level, and the quality differences between reclaimed water and conventional water were the deep-rooted factors that affect the price of reclaimed water. In the end, the policy implications regarding the management of reclaimed water prices were proposed from the perspectives of surface-level direct factors, middle-level indirect factors, and deep-rooted factors.

Unconventional water includes reclaimed water, harvested rainwater, desalinated seawater, and mine water. Unconventional water use is considered more of a “mandatory responsibility” in China. The initial allocation of unconventional water emphasizes quantity-centered responsibility allocation while the minimum utilization reflects this responsibility. The unconventional water use responsibility (UWUR) should be tailored to the characteristics of each area, moving away from a ‘more is better’ mindset. However, there is a large research gap in this field. This paper first presented six fundamental principles for unconventional water allocation. Ensuring fairness in allocation involves aligning the allocated amount with urban water usage characteristics. Hence, based on four key features, this paper integrated various socioeconomic and environmental factors to build an initial allocation model. To enhance efficiency, an optimal allocation model was constructed using the zero-sum gains–data envelopment analysis (ZSG-DEA) method. The models were then applied to Jiangsu Province, China, to verify their applicability. The results showed that the projected minimum UWUR allocation (unit: 100 million m³) for each city in 2025 is 1.482 (Nanjing), 1.501 (Wuxi), 0.919 (Xuzhou), 1.029 (Changzhou), 2.977 (Suzhou), 1.497 (Nantong), 0.818 (Lianyungang), 0.766 (Huai’an), 0.875 (Yancheng), 0.920 (Yangzhou), 0.790 (Zhenjiang), 0.858 (Taizhou), and 0.766 (Suqian). The rational and feasible results indicated that the allocation framework proposed in this paper has a certain practicability. Lastly, this paper considered the differences in unconventional water utilization conditions across 13 cities and proposed corresponding measures to improve the utilization. This paper represents a tentative exploration of unconventional water allocation in China and offers theoretical and practical insights for policy-makers to improve territorial spatial planning and sustainable water management.