液化条件下沉积物中氮、磷的释放规律

Release of nitrogen and phosphorus from sediment under liquefaction

湖泊、海岸沉积物中的氮(N)、磷(P)等营养物质可以通过静态扩散或沉积物再悬浮向水体中释放。沉积物再悬浮过程中N、P的释放量可能大于静态扩散的释放量,特别是沉积物液化时再悬浮过程会对水体中N、P浓度产生重要影响。本文利用波浪水槽试验,研究了沉积层中的N、P在静置固结阶段(I)、加波未液化阶段(II)、加波液化阶段(III)中的释放规律。试验结果表明:阶段I水中的总磷(TP)、溶解性总磷(TDP)、总氮(TN)、溶解性总氮(TDN)浓度最低。阶段II水中TP比阶段I提高了数倍,阶段II水中TDP浓度比阶段I平均仅提高了0.2倍;阶段III水中TP和TDP比阶段I分别提高可达59倍和25倍。阶段II和III水中TN、TDN均比阶段I提高了数倍。

Sediments in lakes and coasts can release N and P into the overlying water due to static diffusion or resuspension,the value of which may be higher than that of static diffusion. Moreover,the resuspension under sediment liquefaction may have important impact on the concentration of N and P in water. In this paper,flume experiments were carried out to study the release of N and P at phase of consolidation（ Ⅰ）,non-liquefaction（ Ⅱ）,and liquefaction phase（ Ⅲ）. The results showed that the concentrations of total phosphorus（ TP）,total dissolved phosphorus（ TDP）,total nitrogen（ TN） and total dissolved nitrogen（ TDN） were lowest at phase Ⅰ,the concentration of TP at phase Ⅱ increased several times than those at phase Ⅰ,the concentration of TDP at phase Ⅱ meanly increased by only 0. 2 times than those at phase Ⅰ; the concentration of TP and TDP increased most（ up to 59 times and 25 times,respectively） at phase Ⅲ with 14 cm wave height. The concentration of TN and TDN at both phase Ⅱ and Ⅲ increased several times than those of phase Ⅰ.