| At present,with the continuous acceleration of global industrialization and urbanization,ecological and environmental problems are becoming increasingly prominent,and air quality is constantly deteriorating.The formation of smog around the world is closely related to particulate matter with a particle size of less than 2.5?m(PM2.5),and its impact on human health has also become a major research topic all over the world.A large number of studies have shown that the PM2.5 content in atmospheric particles is closely related to the occurrence and development of respiratory system,cardiovascular system,endocrine system,immune system,nervous system,reproductive system diseases and tumors,but the specific cause The toxic mechanism and the toxic effects of various chemical components are currently unclear.This study is based on the analysis of the main chemical components in PM2.5,to carry out toxicological experiments on human lung epithelial cells.In this study,PM2.5 samples from the northern suburbs of Nanjing in 2016 and 2017 were collected,and the water-soluble ions,heavy metal elements,and water-soluble organic carbon components were determined and analyzed.The PM2.5 samples were proportioned into gradient poisoning pairs Human lung epithelial cells A549 were poisoned,and their biological toxicological effects were evaluated.The results of component analysis show that: the daily average mass concentration of PM2.5 in four seasons is greater than that in summer and autumn,and all seasons exceed China's secondary standard.The proportion of Al and Zn in PM2.5 in four seasons is much higher than other metal elements.SO42-,NO3- and NH4+?collectively referred to as SNA?are the main water-soluble ions in PM2.5,accounting for 69.3-79.9%,indicating that the Nanjing area is seriously affected by secondary pollution.For now,stationary sources are still the main source of pollution in Nanjing.Toxicological studies have shown that PM2.5 can induce an increase in the relative production of ROS in all seasons,and it has a dose-effect relationship with the PM2.5 exposure concentration.The amount of ROS produced in spring and winter is higher than that in summer and autumn.This seasonal difference is not obvious at low concentrations,medium concentrations can be clearly observed,and high concentrations are significantly different.This may be related to seasonal changes of metal elements such as Zn and atmospheric pollution diffusion conditions.Compared with 2016,PM2.5 has a higher degree of oxidative damage to cells and is more toxic in 2017;water-soluble components have a similar mechanism of toxicity to complete particles but have less toxicity.The high rate of apoptosis in late spring and the high rate of apoptosis in early summer result in a high total apoptosis rate in these two seasons.This high apoptosis rate is related to the TOC content in these two seasons.Regression analysis showed that Zn was significantly positively correlated with ROS and apoptosis rate.There may be soluble ligands in WSOC,which reduces the bioavailability of certain metals and dilutes the toxicity of PM2.5.High K+ outside the cell can prevent the decrease of K+ inside the cell,and then prevent apoptosis. |
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