Mercury emission and pollution in Chongqing City, China

Investigation showed that mercury emission in Chongqing City, China is about 2.1 t/a, 70% of which came from coal burning.Mercury in many water bodies have been detected, in vegetables and milk had exceeded the food standard value in some places.

Evolutionary characteristics and driving factors of carbon emission performance at the city level in China

To achieve carbon peak targets,realize carbon neutrality vision,and tackle global climate change,China must improve the carbon emission performance at the city level.Based on the carbon emission performance of 191 prefecture-level cities in China from 1997 to 2017,this paper analyses the evolution characteristics of urban carbon emission performance from three aspects:the overall spatial and temporal evolution,the differences according to both region and city size,and the differences among clusters categorized by carbon emission performance at the city level.This paper also reveals the impact of the social and economic transition on China’s carbon emission performance.The results show that:(1)The overall level of carbon emission performance of Chinese cities is low,and there is a downward trend during the study period.The differences in carbon emission performance among cities are convergent,but there is a wide gap between high and low values.(2)The carbon emission performance of cities in eastern coastal areas is higher than that in non-coastal areas cities.Large urban agglomerations and economically developed regions,such as provincial capitals,are the agglomeration areas of high urban carbon emission performance values.(3)The carbon emission performance level of cities with similar sizes will converge.At the same time,such changes will enhance the differences among carbon emission performances at the city level within the same region.(4)Cities that belong to high urban carbon emission performance clusters are mainly distributed in the eastern region.Such cities are classified into large cities,supercities,and megacities.Compared with low urban carbon emission performance clusters,cities in high urban carbon emission performance clusters show a higher proportion in the medium-high level and high level of carbon emission performance.Moreover,cities in high urban carbon emission performance clusters are more likely to improve their urban carbon emission performance.(5)The economic agglomeration effect,industrial structure adjustment and carbon intensity reduction have a significant impact on improving urban carbon emission performance.Population agglomeration has an incremental effect,and the anticipated benefits of environmental regulation have yet to be fully realized.The impacts of different clusters and different regions are variable.Finally,this paper advances policy enlightenment according to its research findings.

Carbon Emission Measurement and the Decoupling Effect Under the“Double Carbon”Goal in Xi’an,China

Cities generate more than 60%of carbon emissions and are the main battleground for achieving the target.However,there is no unified and standardized measurement methods of carbon emissions in cities.In this paper,we took Xi’an as an example and started by measuring carbon emissions with the new standards.Then,the decoupling of economic development from carbon emissions was studied according to the Tapio decoupling theory.Based on the generalized Divisia index method,the decoupling effort model was proposed to study the impact of carbon emission factors contributing to carbon reduction.The results show:(i)During the period 1995–2021,the carbon emissions of Xi’an increased rapidly,with an average annual growth rate of 6.06%,due to the accelerating pace of urbanization and industrialization.(ii)The energy consumption sector accounted for the largest share of carbon emissions,ranging from 77.38%to 89.46%.Xi’an’s energy structure is primarily based on fossil fuels,especially coal,which holds a significant proportion.To achieve the“double carbon”goal,it is crucial to reduce the dependence on fossil fuels.(iii)The 10th Five-Year Plan was in the state of“expansive coupling”,while other periods were in the“weak decoupling”state from the 9th to 14th Five-Year Plan periods.After the carbon peak year in the 15th Five-Year Plan,it would be in a state of“strong decoupling”.The agricultural production account was the first to achieve a“strong decoupling”state.(iv)The government of Xi’an made efforts to decouple,but these were not enough.Technological innovation played a crucial role in the carbon reduction of Xi’an,and was a key factor in achieving the“double carbon”goal.