Potential use of corn leaf and silk to monitor atmospheric particulate matter

Atmospheric particulate matter (APM) is prevalent in urban and rural areas and poses serious hazards to human health. Compared with the monitoring of APM in urban areas, monitoring of APM in rural areas has been inadequate. In this study, corn leaves and silks were collected from 17 regions of Shandong Province, which is a major corn-producing area in China, to analyze the mass concentrations of PM2.5 and PM10, respectively adsorbed by these materials. The correlation between our results and the local APM monitoring results acquired through conventional methods was analyzed to investigate the possibility of using local crops for APM biomonitoring. Both corn leaf and corn silk were able to effectively retain APM, but the APM contents on corn leaves were not correlated with the APM concentrations in the atmosphere, indicating that corn leaves are not suitable for monitoring APM pollution. In contrast, PM10 content on the corn silk had a weak positive correlation with atmospheric PM10 concentration at the 0.05 level, while the correlation was strongly positive at the 0.01 significance level for the corn silk PM2.5 and atmospheric PM2.5, suggesting that corn silk could retain PM2.5 more effectively. Moreover, the APM concentrations in the coastal areas of Shandong were significantly lower than the APM concentrations in the inland areas. Correspondingly, biomonitoring through corn silks also showed that areas with a low APM concentration were mostly located in coastal areas, but this phenomenon was not revealed by biomonitoring through corn leaves. Therefore, the amount of PM2.5 on corn silk reveals not only the degree of air pollution by PM2.5 but also the distribution of atmospheric PM2.5 pollution and can help trace the pollution source of atmospheric PM2.5. The use of corn silk, which is an agricultural waste, to monitor PM2.5 pollution has considerable application potential.