id	keyword
esrj-37619	elements
esrj-37619	trace
esrj-37619	formation
esrj-37619	lignite
esrj-37619	coal
esrj-37619	nigeria
esrj-37619	icp
esrj-37619	trace elements
esrj-37619	asaba
esrj-37619	analysis
esrj-37619	ogwashi
esrj-37619	table
esrj-37619	samples
esrj-37619	basin
esrj-37619	et al
esrj-37619	geology
esrj-37619	factor
esrj-37619	fus