Surface charge property governing co-transport of illite colloids and Eu(Ⅲ) in saturated porous media

The transport of colloids and radionuclides is sophisticated because of the variety of charge properties between colloidal particles and host subsurface media, which causes great difficulty in establishing a reliable model of radionuclides migration by taking the colloid phase into consideration. In this work,the co-transport of illite colloids(IC) and Eu(Ⅲ) in the quartz sand and iron-coated sand porous media was investigated by column experiments to address the predominant mechanism of charge properties on co-transport. Results showed that Eu(Ⅲ) transport was driven by the illite colloids and electrostatic interaction was critical in governing the co-transport patterns. The promotion of Eu(Ⅲ) transport by IC was attenuated in the iron-coated sand systems;more IC-Eu(Ⅲ) complexes were retained uniformly in the column. The pore throat shrinkage caused by electrostatic attachment between aggregated IC and iron oxides exacerbated the physical straining and size exclusion effect of IC-Eu(Ⅲ) complexes. An aggravated irreversible retention of IC-Eu(Ⅲ) was detected in iron-coated sand column due to the electrostatic attraction of IC-Eu(Ⅲ) to host media. The findings are essential for improving the understanding on the potential transport, retention and release risk of colloids associated radionuclides, and imply that the positively charged permeable reactive barrier is an effective strategy to reduce the transport risk of colloid associated radionuclides.

Digital Trade Rules and the Position of Chinese Enterprises in the Global Value Chain

Digital trade rules and higher positions of enterprises in the global value chain(GVC)are both important topics in the context of high-quality economic development.This paper refers to the data of RTA digital trade rules concluded by China in the TAPED database in 2000-2014 and the matched data in the WIOD database,the China Customs Import and Export Database and the China Industrial Enterprise Database to investigate the effects of digital trade rules on Chinese enterprises as to their ascending GVC positions.It finds that signing the RTA digital trade rules can steadily and significantly promote the position ascendance;compared with the digitalization rules on trading objects,signing the digitalization rules on trade modes produces greater effects of driving up the positions,which are realized mainly via the three channels of advancing cross-border flow of R&D factors,promoting corporate digital transformation,and improving professional management.Digital trade rules that are horizontally broader and vertically deeper are in greater favor of Chinese enterprises for ascending in the global value chain,which is especially evident among those in digital industry and processing trade.During the negotiations of digital trade rules,it's imperative to pay close attention to the rules on e-commerce cooperation,awareness of e-commerce importance,intellectual property protection,attempts in big data-related trade in goods,and cross-border data flow,so as to secure the core interests of Chinese enterprises in gaining higher positions.This paper offers great policy implications as to how to sign digital trade rules by China in the future and how to select partners in greater support for Chinese enterprises to ascend to the middle and high end of the global value chain.

谁从最低工资调整中获益?——基于2018年广东最低工资调整的评估调查

最低工资制度对提高低工资劳动者收入水平具有积极作用,是国家干预收入分配、促进共同富裕的一项重要政策工具。本文研究了针对2018年广东省最低工资标准调整的调查数据,发现:第一,最低工资调整对低收入群体收入增长起到了积极作用,新标准实施后低工资群体出现收入增长的可能性更大,但也会对高工资群体产生溢出效应;第二,工资结构是最低工资促进职工工资增长的作用路径,即加班工资占总工资收入比例越高,最低工资调整之后,工资增长的可能性越大。第三,从最低工资调整获益来看,低技能劳动者对加班工资的依赖更大。本文进一步肯定了最低工资制度对工资劳动者收入增长的重要作用,彰显了最低工资制度在减少贫困和促进分配公平方面的政策价值。但企业自主设置的薪酬结构抑制了最低工资提升的收入分配效应,抵消了最低工资制度带来的用工成本冲击,这也是当前最低工资制度在执行过程中面临的主要难题。