Can tree-ring chemistry be used to monitor atmospheric nanoparticle contamination over time?

Abstract

Industrial activities and human population growth have resulted in an unprecedented increase in the release of particulate matter (PM) into the environment. Nanoparticle (NP) contamination is widespread and affects all terrestrial and aquatic ecosystems, putting humans and environment at risk. Several studies on the impact of PM and NPs on human health have been conducted over the past two decades, but their effects on plants are still poorly understood. What happens to them in forest ecosystems and trees has yet to be explored. In this paper, we review the literature on the capacity of trees to be used as bioindicators and proxy recorders of past air pollution events. Current research indicates that ultrafine particles can be taken up and translocated to different parts of a tree by physical and chemical processes, as we present studies of plant uptake and translocation processes of NPs in trees. Tree-ring chemistry, i.e., dendrochemistry, has been successfully used to reconstruct trace metal deposition from a variety of sources of pollution, including cars, metal refineries and coal burning. The use of dendrochemistry in environmental monitoring seems promising particularly given the presence of recent development of analytical tools, and is likely to provide useful data on atmospheric NP contamination that could not be obtained from any other source. However, still relatively little is known about the dynamic relationships between NPs and trees. We therefore discuss what future dendrochemical research is needed to make dendrochemical analyses as accurate as possible for monitoring atmospheric nanoparticle contamination over time.