The release behavior of inorganic nitrogen and phosphorus in sediment during disturbance
ABSTRACT Sediments and surface water were sampled in a tide flat in the Huiquan Bay, Qingdao, China in January 2004 to simulate the
exchange of NH4-N/NO3-N/PO43− between sediments and surface water. A working system was designed with which samples were shaken at 60, 120 and 150 revolutions
per minute (r/min). Experiment results show that NH4-N concentration in water at shaking rate of 60 r/min decreased gradually, while at 120 r/min increased gradually. In resuspension,
fine-grained sediments contributed most NH4-N to the seawater, followed by medium-grained and coarse-grained sediments. The NO3-N concentration in water had a negative relation with the shaking rate; the medium-grained sediments contributed more NO3-N to seawater than the coarse-and fine-grained sediments. The PO43− concentration is positively related with the shaking rate, the fine-grained sediments were the main N and P contributor to
the seawater, followed by medium-and coarse-grained sediments.