The honey bee as an active and mobile sampler of pollutant particulate matter in Parma

The honey bees (Apis mellifera L.) is a well-known bioindicator of environmental contamination. During the wide-ranging foraging activity, the bee strongly interacts with vegetables, air, soil, and water surrounding the hive, and pollutants from these sources (e.g. heavy metals, radionuclides, VOCs and pesticides) are brought back to the hive. Recently, it has been demonstrated that the forager bee is an ideal tool also for monitoring airborne PM, an emergent pollutant whose exposure is ubiquitous and linked with several adverse health effects. In early spring 2017, during a citizen science project involving students from high school, honey bees were used for monitoring PM in a highly industrialised areas of the Parma Municipality, characterised by the presence of an incinerator, a highway and a high-speed railway. Later on, within the Ecoresiliente Project funded by the Università Cattolica and with the collaboration of the Università Milano Bicocca, a monthly collection of forager bees and pollen grains along the whole productive season led us to highlight the specific role of the different anthropogenic emission sources. Methods. Worker bees were collected monthly, from April to October, from the hive. Fore wings and pollen grains were analysed by means of a Scanning Electron Microscope (SEM) coupled with X-ray spectroscopy (EDX). Airborne dusts were then characterized dimensionally, morphologically and chemically. Results. Both the bees and the pollen grains displayed a high number of inorganic particles from both natural and anthropogenic origin. PM10, PM5, PM2.5, PM1 and several ultrafine dusts (PM<0.1) have also been observed. The morphological and chemical characterization led us to highlight the environmental presence of many compounds possibly emitted from the incinerator and the traffic. Conclusions. Our study confirms that coupling the use of an efficient PM sampler like the honey bee with SEM/EDX analyses can provide accurate information on the environmental presence of airborne PM pollutants and on the specific contribution of different emission sources.