Keywords: monitoring land use Substances: 1-Naphthylacetic acid (PRPINYUDVPFIRX-UHFFFAOYSA-N) 3-5-Diiodo-L-tyrosine (NYPYHUZRZVSYKL-ZETCQYMHSA-N) Acetochlor (VTNQPKFIQCLBDU-UHFFFAOYSA-N)