id	keyword
brj-23686	ppb
brj-23686	et al
brj-23686	species
brj-23686	doi
brj-23686	pollution
brj-23686	metal
brj-23686	tree
brj-23686	concentrations
brj-23686	changes
brj-23686	average
brj-23686	species sn
brj-23686	air
brj-23686	directions
brj-23686	article
brj-23686	north
brj-23686	bark