Peat moss adsorption of simazine was examined using laboratory batch adsorption and field wetland cells with dimensions 1.2m wide x 4.9m long x 0.3m deep.  Simazine adsorption on peat was examined using coarse versus fine particle sizes, mortal and pedestal grinding versus Wiley-Mill cutting, and autoclaved versus non-autoclaved peat. One or two g of peat was added to erlenmeyer flasks and shaken for 24 hours with 150 mL solutions of simazine (0, 0.5, 1.0, 1.5, 2.0 and 2.5 ug/mL). The adsorption coefficient was 450 mL/g when all treated peat (except autoclaved) was combined.  There was a “solids” effect as the 1 g peat adsorbed more simazine per g then did the 2 g of peat.   At 2 ug/mL simazine added,  41% simazine was adsorbed, while at 1 ug/mL simazine added, 57.6% of simazine was adsorbed.  Simazine adsorption was greatest for the smaller particles on a 200 mesh sieve (50%) compared to the larger particles on a 30 mesh sieve (38%). The fibrous peat hair fraction adsorbed 44% of simazine. At pH 10 simazine sorption was 21% compared to pH 2-8 (39-44.7%).  Autoclaved peat sorbed 33% of simazine compared to the other treatments which sorbed 44%.  Peat adsorbed from 21-63% simazine in the batch adsorption experiments depending on the simazine concentration, pH, particle size, and pretreatment.    Peat removed 81-100% of simazine in the field at 1 and 3 d hydraulic retention times. There was no difference when flow rate was doubled nor between 1 and 3 d hydraulic retention times.  The larger percent of simazine removed in the field was partially attributed to lower simazine mass loading rates of peat in the field compared to the batch adsorption studies.