Mechanisms of plant pollutant uptake as related to effective biomonitoring

Abstract

Biomonitoring is a method that uses the responses of plants or animals to their surroundings to evaluate the status of an environment. Among taxonomic groups, pine needles and mosses are widely used for biomonitoring, especially for atmospheric environments. However, several studies have indicated that each of these plants reacts differently to changes in their habitat. Here, we characterized these contrasting responses and investigated the causes of these differences by comparing atmospheric pollutants (polycyclic hydrocarbons: PAHs) that accumulated in pine needles and mosses. Our results revealed that pine needles absorbed lower molecular weight PAHs, whereas mosses preferentially accumulated higher molecular weight PAHs. Furthermore, the comparison of their PAH isomer ratios showed that the pollution sources were not identical, even though the plant samples were collected from nearly the same sites. These differences can be explained by their distinct leaf structures and uptake mechanisms, as well as the influence of soil particles. Our novel results suggest that both pine needles and mosses can be used as bioindicators to assess PAH pollution multi-directionally.