Arsenic leaching and speciation in C&D debris landfills and the relationship with gypsum drywall content.

•Arsenic leaching and speciation in C&D debris landfills was investigated.•Arsenic leaching decreased with increasing sulfide up to about 1000μg/L.•Arsenic leaching increased when sulfide is greater than 1000μg/L.•The formation of thioarsenic ions at high S2− (>1000μg/L) favors arsenic leaching.