Characteristics and source apportionment of PM_(2.5) under the dual influence of the Spring Festival and the COVID-19 pandemic in Yuncheng city

Based on the online and membrane sampling data of Yuncheng from January 1st to February 12th,2020,the formation mechanism of haze under the dual influence of Spring Festival and COVID-19 (Corona Virus Disease) was analyzed.Atmospheric capacity,chemical composition,secondary transformation,source apportionment,backward trajectory,pollution space and enterprise distribution were studied.Low wind speed,high humidity and small atmospheric capacity inhibited the diffusion of air pollutants.Four severe pollution processes occurred during the period,and the pollution degree was the highest around the Spring Festival.In light,medium and heavy pollution periods,the proportion of SNA (SO_(4)^(2-),NO_(3)-and NH_(4)^(+)) was 59.6%,56.0%and 54.9%,respectively,which was the largest components of PM_(2.5);the[NO_(3)-]/[SO_(4)^(2-)]ratio was 2.1,1.5 and 1.7,respectively,indicating that coal source had a great influence;the changes of NOR (nitrogen oxidation ratio,0.44,0.45,0.61)and SOR (sulphur oxidation ratio,0.40,0.49,0.65) indicated the accumulation of secondary aerosols with increasing pollution.The coal combustion,motor vehicle,secondary inorganic sources and industrial sources contributed 36.8%,26.59%,11.84%and 8.02%to PM_(2.5)masses,respectively.Backward trajectory showed that the influence from the east was greater during the Spring Festival,and the pollutants from the eastern air mass were higher,which would aggravate the pollution.Meteorological and Spring Festival had a great impact on heavy pollution weather.Although some work could not operate due to the impact of the COVID-19 epidemic,the emission of pollutants did not reduce much.

Compositional characteristics and toxicological responses of human lung epithelial cells to inhalable particles (PM_(10)) from ten typical biomass fuel combustions

As the primary component of haze,atmospheric inhalable particulate matters(PMio)are highly detri-mental to human health.Biomass combustion is one of China's most pivotal sources to aerosols pollution,inducing non-negligible emissions and uncertain risks.PMio samples directly from 10 representative biomass fuel combustion sources(2 groups covering the reality widely:straws of rice,wheat,corn,corncob,soybean,peanut,rape,sesame;and branches of pine,peach)were collected using the dilution channel sampler and analyzed for chemical compositions and in vitro cytotoxicity to human lung epithelial cell lines A549.The components of PMio are dominated by organic carbon(OC),followed by Water-soluble K+and Cl,and rich in metals Fe,Zn,Cr,and Ni.Generally,PMio emitted from biomass fuel combustions can weaken the antioxidant capacity of cells,and straws emissions,especially rape and peanut straws,show stronger ability to further induce oxidative stress and inflammatory damage than fuelwoods,owing to the key toxic roles of Cr,Ni,and Co.Therefore,reducing the specific source emis--sions of PMio from crop straw combustions rich in heavy metals could be an effective oriented strategy to improve environmental air quality and control aerosols pollution precisely for protecting public health.