粒径和底床地形对沉积物中有机磷释放的影响

主要研究了2种沉积物粒径（35 μm和130 μm）及底床微地形对沉积物中内源溶解性有机磷释放的影响。选取某浅水湖泊沉积物为研究对象，对其人工污染溶解性有机磷，利用室内循环直流水槽顶盖驱动流模拟风生流，考察静态和风生流作用下，不同粒径沉积物及底床微地形对溶解性有机磷释放的影响。实验结果表明：在20 cm·s-1及38 cm·s-1 2种驱动流速条件下，35 μm粒径沉积物实验组中沉积物有机磷释放速率均大于130 μm实验组。对于35 μm粒径沉积物实验组，在20 cm·s-1驱动水流扰动下，沉积物有机磷的平衡释放量为0.44 mg·L-1，在38 cm·s-1驱动水流扰动下为0.49 mg·L-1；对于130 μm粒径沉积物实验组，在20 cm·s-1和38 cm·s-1 2种扰动下的沉积物有机磷平衡释放量分别为0.29 mg·L-1、0.30 mg·L-1；驱动流速的提高促使达到平衡状态时的释放量提高，小粒径沉积物，提高驱动流速更利于平衡释放量的提高，且高驱动流速缩短达到释放平衡所需的时间。在底床微地形（对地形的描述采用y=0.1sin2πx）实验中发现，静态条件下，波峰处上覆水有机磷浓度首先逐渐降低至0.18 mg·L-1，其后升高至0.40 mg·L-1并达到平衡，而波谷处则不断上升至极大值0.87 mg·L-1，其后下降至0.77 mg·L-1并达到平衡；而在20 cm·s-1的驱动水流扰动下，波峰波谷处上覆水有机磷浓度变化较为一致，均逐渐增长至极大值0.39 mg·L-1和0.45 mg·L-1后达到平衡状态。此外，在静态和动态条件下，波谷处上覆水中有机磷含量始终高于波峰处。

Impact of grain sizes and bed micro landform on release of soluble organic phosphorus (SOP) from sediment

This experiment mainly studied the impact of two grain sizes of sediment (35 μm and 130 μm)and specific lakebed landform,on the release of soluble organic phosphorus (SOP)from the sediment. The sediments from one end of orange isle were selected as the subject,which were then manually "polluted" with SOP. The indoor circulation straight-flow flume was applied to simulate open channel flow,so as to explore,under both static and dynamic conditions,how sediments of different grain size and specific landform impact the release of SOP. The test results showed that,under the two lid-driven flow rates of 20 cm·s-1 and 38 cm·s-1,the release rate of SOP in the test group of grain size 35 μm was always greater than that in the 130 μm test group. For the 35 μm test group,with the lid-driven flow rate of 20 cm·s-1,the equilibrium release amount of SOP was 0.44 mg·L-1,whereas it was 0.49 mg·L-1 with a lid-driven flow rate of 38 cm·s-1. For the 130 μm test group,the equilibrium release amounts of SOP were 0.29 mg·L-1 and 0.30 mg·L-1,under the flow rates of 20 cm·s-1 and 38 cm·s-1,respectively. Increase in the lid-driven flow rate increased the amount of SOP released only slightly,once the absorb-release equilibrium was achieved. As for the smaller grain size,the increase in the flow rate is conducive to an increase in the release amount in equilibrium. Moreover,the increase in the lid-driven flow rate decreased the time needed to achieve the equilibrium. In the test of the specific landform (which is shaped according to the expression y=0.1sin2πx),under static conditions,the SOP near the crest drops at first and is bottomed at 0.18 mg·L-1,but then rebounds and peaks at 0.40 mg·L-1,reaching the equilibrium thereafter. The SOP near the valley initially keeps rising until it peaks at 0.87 mg·L-1,then falls back and eventually reaches the equilibrium at 0.77 mg·L-1. On the other hand,with the lid-driven flow rate of 20 cm·s-1,the SOPs near both the crest and the valley are in sync with each other,increasing monotonically,peaking at 0.39 mg·L-1 and 0.45 mg·L-1,respectively,eventually achieving equilibrium. In addition,under both static and dynamic conditions,the SOP near the valley appears higher than near the crest.