[Characteristics, Impact Factors and Potential Sources of PM_2.5 Pollution for Hainan Island]

Based on the environmental monitoring data and meteorological observational data in Hainan Island from 2015 to 2021, the PM_2.5-polluted characteristics, influencing factors, and potential contributing regions were analyzed using the backward trajectory simulation, cluster analysis, potential source analysis function （PSCF）, and concentration weight trajectory （CWT） methods. The results showed that PM_2.5 in Hainan Island had an obvious seasonal variation, with the highest in winter （22.6 μg·m^-3）, followed by that in autumn and spring （17.38 and 16.53 μg·m^-3, respectively）, with the lowest in summer （9.79 μg·m^-3）. In the past seven years, there were 30 days in Hainan Island in which PM_2.5 concentration exceeded the standard. The annual average and four seasons of PM_2.5 showed a significant downward trend, and the climatic change rates were -0.97 （annual mean）, -1.09 （spring）, -0.61 （summer）, -0.83 （autumn）, and -1.25 （winter） μg·（m³·a）^-1. PM_2.5 in Hainan Island was highly correlated with gaseous pollutants, with correlation coefficients of 0.471 （SO₂）, 0.633 （NO₂）, 0.479 （CO）, and 0.773 （O₃-8h）, all passing a significance level of 0.01. PM_2.5 was positively correlated with average wind speed and atmospheric pressure and negatively correlated with precipitation, relative humidity, sunshine duration, average temperature, and total solar radiation. Among them, average temperature, relative humidity, and total solar radiation were the main dominant meteorological factors on PM_2.5 in Hainan Island. Backward trajectory and potential source analysis revealed that PM_2.5 concentration was high （≥20 μg·m^-3） in winter and autumn, which was influenced by airflow from inland regions, and Fujian, Zhejiang, Hunan, Jiangxi, Guangdong, and Guangxi provinces were the main potential sources of PM_2.5 in Hainan Island.