Studying the impact of land urbanization on smog pollution has important guiding significance for the sustainable development of cities. This study adds the spatial effect between regions into the research framework of smog pollution control in China. On the basis of a panel dataset of 31 province-level administrative regions in China from 2000 to 2017, we investigate the impact of land urbanization on smog pollution. We construct a spatial weight matrix and use Moran’s I statistic and the spatial autoregressive panel data model. The research results show that land urbanization and smog pollution have an inverted U-shaped relationship. With the advancement of land urbanization, the area’s smog pollution first increases and then decreases. However, in general, China has not passed the inflection point and is still at a stage where increasing land urbanization rate aggravates smog pollution. Moreover, the country’s smog pollution has a significant spatial positive correlation that shows agglomeration. In that context, multiple environmental governance entities, including the government, enterprises, and the public, need to collaborate on measures to reduce smog pollution. Future urban construction in China will need to integrate solutions that address the current nexus between urbanization and smog pollution to achieve green and sustainable development.

The CO₂ emissions from marine fisheries have a significant impact on marine ecology, despite generally being overlooked in studies on global climate change. Few studies have estimated the carbon emissions from marine fisheries while taking into account all pertinent sectors. This study evaluated marine fisheries’ CO₂ emissions based on three sectors: marine fishing, mariculture, and the marine aquatic product processing industry. Kernel density estimation and the spatial Durbin model were used to investigate the spatial and temporal characteristics and the key socioeconomic drivers of the CO₂ emissions from marine fisheries in 11 coastal provinces of China from 2005 to 2020. The results are as follows: (1) marine fishing is the sector that produces the most CO₂ emissions; trawling operations generate more CO₂ than all other modes of operation combined; (2) China’s marine fisheries’ CO₂ emissions show a rising, then declining, trend, with significant differences in coastal provinces; (3) the development of the marine fishery economy and trade have a positive driving effect on CO₂ emissions, the expansion of the tertiary industry does not decrease CO₂, the technical advancement and income growth of fishermen are negatively related to carbon emissions, and the effect of environmental regulation has failed to pass the significance test; (4) the carbon emissions of marine fisheries have significant spatial spillover effects.

National marine parks (NMPs) are a crucial form of marine protected areas that serve an essential function in safeguarding marine ecosystems and the related inland urban ecosystems. Though 30 coastal cities in China have established NMPs, little is known about the ecological benefits national marine parks contribute to surrounding areas. This study takes China’s coastal cities as an example and employs a multi-period DID model to investigate how eco-efficiency responds to the establishment of national marine parks, based on panel data from 2003 to 2020. The results show that the establishment of NMPs contributed to a 3.87% enhancement in the eco-efficiency of coastal cities. This finding remains robust after a series of robustness tests such as PSM-DID. In addition, significant heterogeneities are captured, with NMPs exhibiting a more substantial enhancement effect for cities along the East China Sea and South China Sea. NMPs with a large area increased the eco-efficiency of coastal cities by 5.18%, but small-area NMPs failed the significance test. A mechanism analysis further reveals that NMPs could improve the eco-efficiency of coastal cities by optimizing the industrial structure, enlivening the local economy, and inhibiting sewage pollution behaviors. This study provides evidence of the impact of NMPs on local eco-efficiency in developing countries.