Keywords: monitoring land use Substances: 1-Naphthylacetic acid (PRPINYUDVPFIRX-UHFFFAOYSA-N) 3-5-dibromo-4-hydroxybenzoic acid (PHWAJJWKNLWZGJ-UHFFFAOYSA-N) Acetochlor (VTNQPKFIQCLBDU-UHFFFAOYSA-N)