Abstract: An experiment was conducted to study the removal of  total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N) and  total phosphorus (TP) by three hydrophyte plant species, Iris sanguinea, Acorus calamus, and Iris pseudacorus. The eutrophicated water in laboratory was prepared according to the eutrophication status of Dahuofang Reservoir and its tributary inflow. The results showed that after 28 days growing in the water, the removal rates on the four pollutants were 78.1%, 73.1%, 84.8% and 90.3% by I. sanguinea, 73.4%, 90.7%, 63.1% and 89.1% by A. calamus, and 83.9%, 77.3%, 75.0% and 93.8% by I. pseudacorus, respectively. The removal efficiencies on four pollutants by the three plants showed similar variations: From initial high rate to gradually lower rate. Removal effect was obvious for NO₃^--N during the whole experiment while more obvious for TN and NH₄⁺-N during the first 14 days, and more obvious for TP during the first 21 days.

Key words: spatial variation, thermal property., diurnal change, stem temperature