Abstract:
This study mainly focuses on the comparison of airborne microplastics (AMPs)
deposition between the surface of epiphytic crustose lichens and the bark of trees
in the surrounding area of an open dumpsite and a plastic crusher plant in
Kanadola, Sri Lanka. Epiphytic crustose lichen samples and bark samples were
collected at three sampling zones by using stratified random sampling techniques
at different distances from the center of the plastic crusher plant: the close zone
(n=4, 50 m), the intermediate zone (n=3, 100 m), and the remote zone (n=3, 200
m). Background control samples (n=3) were collected from the Kumbalgama area
(undisturbed forest). At each sampling point, epiphytic crustose lichens were
collected carefully, removing them from selected trees (bark Type-Smooth). Each
sampling point corresponds to a tree. Additionally, bark samples were collected
from the area adjacent to where the lichen samples were removed from the tree.
Epiphytic crustose lichen and adjacent bark samples were collected from the tree,
covering the area from ground level up to a height of 1.5 m. Anthropogenic
microplastics were visually inspected with a microscope after acid digestion of
lichen and bark samples. A hot needle test was used to identify microplastic in
the quantification of the AMPs. The total number of microplastics found per 1 g
of the dry weight of lichen and bark was compared using one-way ANOVA (with
a 95% confidence interval). Results revealed a statistically significant difference
(P<0.05, P=0.024) in microplastic deposition between lichen and bark, and
lichen showed a higher deposition level of airborne microplastics. This study
demonstrates, for the first time in the world, the potential of epiphytic crustose
lichens as a biomonitor for airborne microplastics.
