Classification and 3-D distribution of upper layer water masses in the northern South China Sea

Using the fuzzy cluster analysis and the temperature-salinity(T-S) similarity number analysis of cruise conductivity-temperature-depth(CTD) data in the upper layer(0–300 m) of the northern South China Sea(NSCS), we classify the upper layer water of the NSCS into six water masses: diluted water(D), surface water(SS),the SCS subsurface water mass(U_S), the Pacific Ocean subsurface water mass(U_P), surface-subsurface mixed water(SU) and subsurface-intermediate mixed water(UI). A new stacked stereogram is used to illustrate the water mass distribution, and to examine the source and the distribution of U_P, combining with the sea surface height data and geostrophic current field. The results show that water mass U_P exists in all four seasons with the maximum range in spring and the minimum range in summer. In spring and winter, the U_P intrudes into the Luzon Strait and the southwest of Taiwan Island via the northern Luzon Strait in the form of nonlinear Rossby eddies, and forms a high temperature and high salinity zone east of the Dongsha Islands. In summer, the U_P is sporadically distributed in the study area. In autumn, the U_P is located in the upper 200 m layer east of Hainan Island.

Environmental taxation and regional inequality in China

In order to combat environmental pollution, China enacted the Environmental Protection Tax Law in early 2018. Yet the impacts of the environmental tax on individual regions with different socioeconomic statuses, which are crucial for social justice and public acceptance, remain unclear. Based on a MultiRegional Input-Output(MRIO) table and a nationally regulated tax payment calculation method, this study analyzes the distributional impacts of an environmental tax based upon province’s consumption from both inter-provincial and rural-urban aspects. The national tax revenue based on the current levy mechanism is estimated to be only one seventh of the economic loss from premature mortality caused by ambient particulate matter(PM2.5). The taxation may slightly alleviate urban-rural inequality but may not be helpful with reducing inter-provincial inequality. We further analyze two alternative levy mechanisms. If each province imposes taxes to products it consumes(rather than produces, as in the current mechanism), with the tax rate linearly dependent on its per capita consumption expenditure, this would moderately increase the national tax revenue and significantly reduce inter-provincial inequality.To better compensate for the economic costs of air pollution and reduce regional inequality, it would be beneficial to increase the tax rate nationwide and implement a levy mechanism based on provincially differentiated levels of consumption and economic status.

跨界PM_(2.5)污染健康影响及其不平等性的历史演化

大气传输导致的PM;跨界输送会引起重大的跨境健康影响.在过去几十年间,各区域人为源污染物排放发生了巨大且不同的变化,但是,由此产生的全球跨界健康影响及其中隐含的健康不平等性问题仍不清楚.本研究发现,在1950~2014年间,全球人为源PM_(2.5)累计导致了1.86(95%CI:1.16~2.56)亿例过早死亡,其中约14%是跨界PM;所致.在四个不同富裕程度的地区中,从对跨界PM;过早死亡的人均贡献的角度来说,越富裕的地区所造成的累计跨界健康影响越严重,而最贫穷的地区承受着最严重的跨界健康负担.这意味着,大气输送所造成的跨界健康影响不平等性问题十分严峻.并且,跨界健康效应及其不平等性随时间的变化也十分显著.降低PM;跨界污染需要全球紧密合作,而合作的基础应当将历史责任以及健康不平等性问题考虑在内.

Effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke

Diffusion of oxygen in the ash layer usually dominated the combustion of oil shale semicoke particles due to the high ash content.Thus,effective diffusivity of oxygen in the ash layer was a crucial parameter worthy of careful investigation.In this paper,the effective diffusivity of oxygen in the ash layer of Huadian oil shale semicoke was measured directly using an improved Wicke-Kallenbach diffusion apparatus.The experimental results showed that higher temperature would lead to a higher effective diffusivity and a thicker ash layer had the negative effect.Especially,the effective diffusivity along the direction perpendicular to bedding planes was much lower than that along the direction parallel to bedding planes.In addition,an effective diffusivity model was developed,which could be used to describe the mass transfer of oxygen in the ash layer of oil shale semicoke.