id	keyword
aiol-7576	metals
aiol-7576	elements
aiol-7576	sediments
aiol-7576	trace
aiol-7576	trace elements
aiol-7576	reservoir
aiol-7576	concentrations
aiol-7576	g–1
aiol-7576	contamination
aiol-7576	nigeria
aiol-7576	water
aiol-7576	values
aiol-7576	arsenic
aiol-7576	mean
aiol-7576	background