Bioconcentration capacity of moss Leskea angustata Tayl., for heavy metals and its application in the atmospheric biomonitoring of a metropolitan area

Abstract

In this work, the bioconcentration capacity of heavy metals Cd, Cu, Pb and Zn in the moss Leskea angustata Tayl., exposed under laboratory conditions was evaluated, and subsequently the usefulness of moss for the heavy metals’ biomonitoring associated with suspended particulate matter in air of the Toluca Valley Metropolitan Area was determined by means of the moss bag technique. To achieve the aims, bioassays were carried out in the laboratory with the moss, the exposure for a period of 6 months of the moss bags in the sites of the Automatic Atmospheric Monitoring Network of the Government of the State of Mexico and their subsequent analysis through of elemental and structural characterization techniques. The results of the bioassays on the moss L. angustata, demonstrate that this moss has adequate bioconcentration capabilities to be used as a biomonitor of heavy metals in polluted areas. The structural characterization of the moss L. angustata, shows that this moss has good adsorption characteristics (presence of functional groups, surface area of 19.87 m2 g-1, average pore diameter equal to 2.86 nm and a total pore volume of 0.014218 cm3 g-1). The significant correlations between Cd–Zn–Pb and between Pb and Zn with PM2.5, as well as a strong correlation between Pb and Zn with PM10, allow us to establish that these three metals have their main origin in the domestic combustion of wood and liquid petroleum gas (LP gas), as well as emissions from agricultural burning in the study area. Cu has a different origin than other metals and PM10 and PM2.5. The findings demonstrate a strong association between anthropogenic activities - such as domestic wood and LP gas combustion, agricultural burning emissions, vehicular emissions, tire wear, and industrial activities - and the detection, entrapment, and accumulation of several heavy metals by L. angustata moss.