|关键词: 泥水界面 无机氮 交换通量 京杭大运河
|Simulated Study on the Exchange of the Inorganic Nitrogen (IN) at the Sediment water Interface in Changzhou Segment of the Grand Canal
|The behavior of different nitrogen forms at sediment water surface was studied, based on the simulated experiments on the release of IN at 4 sites in high flow period, mean flow period and low flow period in Changzhou segment of the grand canal. Results showed thatNH+
４-Nwas released from sediment to overlying water all the year. The exchange rates were［182.3mg／(m2 during mean flow period,［94.0mg／(m2?d)］during high flow period and ［29.5mg／(m2?d)］ during low flow period following descending order, while the flux mass of downstream sites that was seriously polluted was proved to be higher than those at other sites; sediment was acted as the main source of NO-３-N in overlying water in high flow period, while it became the sink in the mean and low flow periods. In addition, the adsorption rate during mean flow period was 6 times as that in low flow period. The exchange behaviors of NO-２-Nwere represented as the characteristics of sediment adsorption, while an extremely low exchange rate occurred in low flow period. Generally, the amount of DIN inputs into the sediment was much higher than the output from the sediment. Sedimentary adsorption on theNO-３-N with high levels in the overlying waters might be the reason why the sediment pollution aggravated gradually.
|Key words: sediment water surface inorganic nitrogen exchange flux grand canal