Air quality biomonitoring in an urban and industrial hot-spot of Central Italy
Particulate matter (PM) is a complex mixture of solid and liquid airborne particles, characterized by different size, shape, chemical composition, solubility and origin [1]. The high costs associated to the definition of a traditional monitoring network determine an increasing demand for new and low-cost techniques for air pollution monitoring [2]. In this context, leaves are often described as efficient passive biomonitors for airborne pollutants such as particulate matter [3]. Deposition of PM on vegetation is influenced by species-specific characteristic and also by chemical and physical characteristics of PM (dimension, composition, morphology and solubility) [4]. This study reports the evaluation of PM deposition on giant reed leaves (A. donax (L.)), in Terni city, an industrial and urban hotspot of Central Italy. Leaves were collected in six different collection sites along the river Nera that cross the city, in order to evaluate the role of the different emission sources present in this area. The chemical characterization of washed and unwashed leaves allows us to estimate PM deposition on leaf surface. Thanks to the utilization of new and innovative PM samplers (HSRS, Fai Instruments, Fonte Nuova, Italy) it was possible to build an extensive air monitoring network, useful to compare the airborne elemental concentrations with the PM deposition on A. donax (L.) leaves data. The comparison between leaves deposition results and atmospheric concentrations of PM10 elemental components allowed us to evaluate the efficiency of A. donax leaves as biomonitors for PM pollution. Deposition data confirmed to be reliable for elements such as Ni, Mo and Cr emitted at high concentrations by the steel plant. The obtained results proved the influence of chemical and physical characteristics on the deposition efficiency of each elemental component.