▁its ▁source . ▁It ▁can ▁be ▁defined ▁as ▁the ▁study ▁of ▁the ▁sources , ▁re actions , ▁transport , ▁effects , ▁and ▁f ates ▁of ▁chemical ▁species ▁in ▁the ▁air , ▁soil , ▁and ▁water ▁environments ; ▁and ▁the ▁effect ▁of ▁human ▁activity ▁and ▁bi ological ▁activity ▁on ▁these . ▁Environment al ▁chem istry ▁is ▁an ▁inter dis cipl inary ▁science ▁that ▁includes ▁atmos pher ic , ▁aqu atic ▁and ▁soil ▁chem istry , ▁as ▁well ▁as ▁heavily ▁re lying ▁on ▁analyt ical ▁chem istry ▁and ▁being ▁related ▁to ▁environmental ▁and ▁other ▁areas ▁of ▁science . ▁ ▁Environment al ▁chem istry ▁involves ▁first ▁understanding ▁how ▁the ▁un cont amin ated ▁environment ▁works , ▁which ▁chemical s ▁in ▁what ▁concentr ations ▁are ▁present ▁naturally , ▁and ▁with ▁what ▁effects . ▁Without ▁this ▁it ▁would ▁be ▁impossible ▁to ▁accur ately ▁study ▁the ▁effects ▁humans ▁have ▁on ▁the ▁environment ▁through ▁the ▁release ▁of ▁chemical s . ▁ ▁Environment al ▁chem ists ▁draw ▁on ▁a ▁range ▁of ▁concepts ▁from ▁chem istry ▁and ▁various ▁environmental ▁sciences ▁to ▁assist ▁in ▁their ▁study ▁of ▁what ▁is ▁happening ▁to ▁a ▁chemical ▁species ▁in ▁the ▁environment . ▁Import ant ▁general ▁concepts ▁from ▁chem istry ▁include ▁understanding ▁chemical ▁re actions ▁and ▁equations , ▁solutions , ▁units , ▁sampling , ▁and ▁analyt ical ▁techniques . ▁ ▁Cont am ination ▁A ▁cont amin ant ▁is ▁a ▁subst ance ▁present ▁in ▁nature ▁at ▁a ▁level ▁higher ▁than ▁fixed ▁levels ▁or ▁that ▁would ▁not ▁otherwise ▁be ▁there . ▁▁ ▁This ▁may ▁be ▁due ▁to ▁human ▁activity ▁and