Keywords: trace analytics stream pyrethroids Systems: stream Substances: Chlorpyrifos (SBPBAQFWLVIOKP-UHFFFAOYSA-N) Cyphenothrin (FJDPATXIBIBRIM-UHFFFAOYSA-N) Empenthrin (YUGWDVYLFSETPE-JLHYYAGUSA-N) Chlorpyrifos-methyl (HRBKVYFZANMGRE-UHFFFAOYSA-N)