RESUMO
Recently, a large number of laboratory studies have focused on the aqueous-phase photochemistry of single organic compound in atmospheric condensed phases, yet few studies have been conducted on the aqueous-phase photochemical oxidation of real-world complex dissolved organic matter (DOM). Therefore, in this work, we report experimental results for the photochemical oxidation of DOM extracts from ambient fine aerosol samples upon direct photolysis or against OH oxidation, under both simulated sunlight and ultraviolet irradiation conditions. The products at different stages of photolysis were analyzed via UV-vis and spectroscopy and soot-particle aerosol mass spectrometry (SP-AMS) to investigate their optical and chemical characteristics. The results demonstrate the effective degradation of DOM under UV irradiation, and the f44 values of the corresponding products aremuch lower than under sunlight irradiation. A variety of carboxylic acids were generated during liquid-phase photolysis, and oxalic acid was found to be the most abundant. The light absorbance and concentration of HULIS did not change significantly under sunlight illumination; however, under UV and UV+·OH conditions, the concentration of HULIS increased continuously with reaction time. The HULIS concentration at 23 h was approximately four times the initial value, indicating the formation of brown carbon species with carboxyl, hydroxyl, and aromatic and other functional groups. Our results show that the increase in light absorptivity and formation rate of brown carbon from DOM are limited when aqueous-phase oxidation occurs under sunlight illumination. In comparison, DOM can constantly decompose into HULIS or small molecules under ultraviolet light illumination, and the light absorptivity of the remaining organic matter may be relatively high, resulting in final products with a high unit mass absorption efficiency (MAE). We have investigated the aqueous-phase oxidation of actual filter extracts for the first time, and our results provide valuable insights to the formation of air pollution complexes.
RESUMO
OBJECTIVES@#The rapid growth of health expenditure has always been the focus of health policy. This study aims to project health expenditure in Shanghai and to carry out policy simulations on the impact of chronic disease prevention programs on health costs in the Healthy Shanghai Initiative.@*METHODS@#Based on the Shanghai health accounts, component-based model was used to project Shanghai total health expenditure of 2020-2035, and the policy stimulation was implemented.@*RESULTS@#In 2020-2035, Shanghai's health expenditure is expected to grow continually, the proportion of total health expenditure in GDP will exceed 8.00% in 2023, reach 9.00% in 2025, and 10.03% in 2035. The proportion of current health expenditure in GDP will exceed 8.00% in 2024 and reach 9.55% in 2035. The chronic disease prevention plan help saving the medical expenditure of respiratory diseases,endocrine system diseases, and circulatory system diseases, accounting 3.28% to 10.58% of total health expenditure.@*CONCLUSIONS@#The sustainability of health financing in Shanghai is facing challenges under the new normal of economy. It is necessary to promote the prevention and control of chronic diseases and strengthen cost control from both the supply and demand sides.
