实现"双碳"目标,是我国实现可持续发展、高质量发展的内在要求,也是推动构建人类命运共同体的必然选择.鉴于此,本研究基于"理性经济人"假设理论,构建了"碳中和政策实施→不同碳中和政策的选择→对林地的影响→不同利用方式的选择→产生相应的碳中和效果"的理论分析框架.在实地访谈式问卷调查的基础上,运用多元无序Logit模型研究政策变量对农户林地利用方式而提出相应的对策建议,为碳中和政策与林地利用政策制定提供参考.

成渝城市群作为中国经济增长第四极,也是我国雾霾频发地之一,属于国家"大气污染防治行动计划"划定的大气污染重点控制区.加快清洁能源替代、构建清洁能源体系是成渝地区控制大气污染的有利依托,是建设"成渝地区双城经济圈"和实现"美丽中国"要求的重要支撑.以促进清洁能源替代改善空气质量为出发点,首先定量评估了成渝地区清洁能源资源禀赋、生产供给能力和利用现状,其次通过与京津冀等地区的比较分析了成渝地区清洁能源替代的前景,最后结合实际情况为成渝地区未来推进清洁能源消纳、加快能源结构调整、坚持大气污染源头防治等方面提出了对策与建议.

基于成渝地区2017年监测数据,运用普通克里金插值法、空间自相关和相关性分析,对该区域PM2.5时空分布特征及影响因素进行了研究.结果表明:成渝地区PM2.5浓度季节变化呈现出冬高(1月最高)夏低(7和8月最低)、春秋居中的规律,日均值整体趋势与月均值变化相似,且呈现为周期性脉冲型起伏变化;区域PM2.5浓度在空间上存在集聚现象,高值主要聚集在成都平原经济区、川南经济区;前体物的二次转化、机动车保有量和燃料燃烧对成渝地区PM2.5浓度有显著影响;从全年来看,该区域的PM2.5浓度与气温、风速、降水量都呈显著负相关.

The road transport sector in megacities is confronted with pressing local air pollution and carbon dioxide (CO2) control issues. To determine effective policy instruments for saving energy and the co-control of air pollutants and CO2, several mainstream measures were examined and compared in Chongqing's road transport sector from 2017 to 2035. An integration assessment framework was developed by combining the Long-range Energy Alternatives Planning (LEAP) system and a set of quantitative methods for evaluating the co-benefits of emission reductions (including the air pollutant equivalent (APeq), co-control coordinate system, and pollutant reduction cross-elasticity (Elsa/b)). Results showed that the shifting transportation modes scenario presented the most significant potential for energy-saving and emission reductions, reducing energy use by 30.9% and air pollutants and CO2 emissions by approximately 27–32% compared with the business as usual (BAU) scenario in 2035. The improving energy efficiency scenario also provided significant co-benefits for reducing air pollutants and CO2 emissions. Nevertheless, the promoting alternative fuel scenario may increase fine particulate matter (PM2.5) emissions by 2.2% compared to BAU in 2035 under the cleanness of regional electricity in 2017. Our findings suggest that the shifting transportation modes were effective measures to reduce air pollutants and CO2 in the short term synergistically, and highlighted the importance of cleaner electricity generation to develop electric vehicles in the medium and long term.

The arrowhead plant stalk (APS) has been investigated as a novel biosorbent for removal of Cd(II), Pb(II), and Cr(III) ions from aqueous solution. The surface physicochemical properties favorable for metals adsorption were systematically characterized. The Langmuir isotherm fitted well with Cd(II) and Pb(II) adsorption process onto APS while Dubinin-Radushkevich model best described Cr(III) sorption. The maximal adsorption capacities of APS for Cd(II), Pb(II), and Cr(III) were up to 38.2, 97.1, and 23.5 mgg(-1), respectively. The adsorption kinetic data of individual metal fitted the pseudo-second order model best. The adsorption of Cd(II) was exothermic, whereas the Pb(II) and Cr(III) underwent endothermic reaction. Overall, this investigation indicated, for the first time, APS is a potentially efficient biosorbent applied in Cd(II), Pb(II), and Cr(III) adsorption. It is also helpful for further utilizing the abundant quantity of APS which were abandoned in dietary arrowhead processing. Practical applicationsThe growing food industry around world generates large quantity of by-products. The high value-added utilization of food processing by-products is one of the most important area in food industry. An attempt was made in present study to use the food by-product, arrowhead plant stalk (APS), as a novel biosorbent for removing Cd(II), Pb(II), and Cr(III) ions. In present study, it was evidenced that the adsorption capacities of APS for Cd(II), Pb(II), and Cr(III) were obviously higher than those of most reported agricultural by-products. This finding is significant for sustainable utilization of food crop arrowhead plant and elimination of environmental issues arising from the abandoned arrowhead plant stalk.