Estimation of reduced greenhouse gas emission from municipal solid waste incineration with electricity recovery in prefecture- and county-level cities of China.

Municipal solid waste (MSW) without proper managements could be a significant source of greenhouse gas (GHG) emissions. MSW incineration with electricity recovery (MSW-IER) is recognized as a sustainable way to utilize waste, but its effectiveness on reducing GHG emissions at the city scale in China remain unclear due to limited data of MSW compositions. The aim of the study is to investigate reduction potential of GHG from MSW-IER in China. Based on the MSW compositions covering 106 Chinese prefecture-level cities during the period of 1985 to 2016, random forest models were built to predict MSW compositions in Chinese cities. MSW compositions in 297 cities of China from 2002 to 2017 were predicted using the model trained by a combination of socio-economic, climate and spatiotemporal factors. Spatiotemporal and climatic factors (such as economic development level, precipitation) accounted for 6.5 %-20.7 % and 20.1 %-37.6 % to total contributions on MSW composition, respectively. The GHG emissions from MSW-IER in each Chinese city were further calculated based on the predicted MSW compositions. The plastic is the main GHG emission source, accounting for over 91 % of the total emission during 2002-2017. Compared to baseline (landfill) emission, the GHG emission reduction from MSW-IER was 12.5 × 107 kg CO2-eq in 2002 and 415 × 107 kg CO2-eq in 2017, with an average annual growth rate of 26.3 %. The results provide basic data for estimating GHG emission in MSW management in China.

Environmental and economic benefits of substituting chemical potassium fertilizer with crop straw residues in China.

Chemical potassium (K) fertilizer plays a crucial role in improving crop productivity, yet its production and application also result in environmental issues including greenhouse gas emission and atmospheric pollution emissions. In addition, the abandon or open burning of crop straw not only causes the wasting of resource, but also creates environmental problems. On-present studies recognize the importance of the substitution of straw resource utilization for chemical K fertilizer, yet whether such action can effectively mitigate the emissions of greenhouse gas and pollutants remains unclear. In this study, we examine the effects of substituting straw for chemical K fertilizer on the emissions of greenhouse gas and pollutants and the associated direct and damage cost implications in China at the provincial level. Results showed that the useable straw contributed 2750 Gg of K from 2000 to 2009 and 3567 Gg from 2010 to 2017, equaling 121% and 57.3% of chemical K fertilizer, respectively. Chemical K fertilizer substitution with straw can also reduce annual emissions of greenhouse gases, ammonia, nitrogen oxide, and fine particulate matter by 664 Gg, 18.5 Gg, 10.7 Gg, and 1.48 Gg, respectively. The average abatement cost reached 4790 million USD during 2000-2009 and 3898 million USD during 2010-2017, respectively. And the mitigation potential of the emissions of greenhouse gas and pollutants and average abatement cost showed a large spatial heterogeneity at the provincial level. Overall, replacing chemical K fertilizer with straw is an efficient strategy to reduce environmental risk and utilize agricultural waste.

Evaluation of the vulnerability to public health events in the Guangdong-Hong Kong-Macao Greater Bay Area.

With the continuous improvement in the integration of urban agglomeration, a multi-functional, socialized, and complex dynamic system, effective prevention and control of emergent public health events have become increasingly important. Based on the Public-Health Vulnerability-Assessment-System of Urban Agglomeration (PVUA), the temporal and spatial differentiation characteristics of vulnerability in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) for the period of 2015-2019 are explored, and the vulnerable cities to public health events are identified in this area. The results can be summarized as follows: (1) The overall vulnerability to public health events in GBA decreases in the investigated period. (2) In the temporal dimension, accompanied by social and economic development, the sensitivity to public health events increases in GBA, and the coping capacity change from stable fluctuation to rapid improvement. (3) From the spatial dimension, the sensitivity level in GBA is low in the west, relatively high in the middle, and high in the southeast; the coping capacity is high in the southeast and low in the northwest; the collaborative governance capacity presents a spatial pattern of being low in the south and high in the north. (4) In the period of study, the vulnerability to public health events in Guangzhou and Jiangmen is stable at the lowest level, while that in Zhaoqing, Foshan, and Hong Kong SAR (Special Administrative Region) gradually reduces; the vulnerability in Shenzhen, Zhuhai, and Dongguan is fluctuating, and that in Huizhou, Zhongshan, and Macao SAR is continually maintained at a higher and the highest level.