UPTAKE KINETICS OF NH4+, NO3- AND H2PO4- BY SUBMERGED MACROPHYTES ELODEA NUTTALLII (ST. JOHN, 1920) AND VALLISNERIA NATANS (JUSSIEU, 1826)

The source of lake eutrophication comes from the excessive input of nitrogen and phosphorus and their uncoordinated proportion, while nitrogen and phosphorus are essential elements for the growth of aquatic plants.Using aquatic plants to treat sewage has incomparable advantages compared with chemical and physical methods.It not only makes the whole process is derived for natural behavior, but also improves landscape and avoids new environmental problems.Studying the uptake kinetics of NH4 + , NO3 -and H2PO4 -of aquatic plants can help us to select the proper aquatic macrophyte according to the status of eutrophic water.In June 2017, the absorption kinetics of NH4 + , NO3 -and H2PO4 -by Elodea nuttallii and Vallisneria natans under the eutrophication stress were studied in indoor simulation experiments at the plant nutrition laboratory of Huazhong Agricultural University of China.The results showed that the Vmax absorbed by NH4 + of Elodea nuttallii and Vallisneria natans at three phosphorus levels decreased with the increase of P concentration.The Km value increased with the increase of P concentration.On three phosphorus levels, in two plants the Vmax of NO3 -decreased with the increase of P concentration.The Km value of NO3 -absorbed by Elodea nuttallii at different levels of phosphorus decreased with the increase of P concentration.The Km of NO3 -on Vallisneria natans increased with the increase of P concentration.The Vmax of H2PO4 -of Elodea nuttallii and Vallisneria natans at three nitrogen levels decreased with the increase of N concentration.The Km value of Elodea nuttallii and Vallisneria natans at three nitrogen levels increased with the increase of N concentration.In eutrophication environment, the stress of submerged plants will affect their nutrient absorption.The nutritive stress of low N,P increased the absorption potential of N,P.High NP nutrition stress reduced the absorption rate and affinity.