不同密度下的鲤鱼扰动作用对沉积物-水界面硝化、反硝化和氨化速率的影响

为研究不同密度下的鲤鱼（Cyprinus carpio）扰动作用对沉积物-水界面硝化、反硝化及硝酸盐氨化速率的影响，实验设置了一个对照组（不放鲤鱼组，用C0表示）和5个不同鲤鱼放养密度组（2、4、6、8、10尾/水槽，分别用C2、C4、C6、C8、C10表示），定期用无扰动底泥采集器采集沉积物样品，乙炔抑制法测定沉积物-水界面的硝化、反硝化及硝酸盐氨化速率，示踪颗粒法测定鲤鱼的物理扰动深度。主要实验结果如下:（1）在5种密度下，鲤鱼对底泥的物理扰动深度主要集中在15 cm。（2）空白组（C0）沉积物-水界面硝化速率显著高于鲤鱼放养组（P0.05），而放养密度较大的C8和C10组，其沉积物-水界面的硝化速率显著高于低密度放养组（C2、C4和C6）（P0.05）。（3）实验期间，空白组（C0）沉积物-水界面几乎检测不出反硝化速率，而鲤鱼放养组则总体表现为放养密度越大，沉积物-水界面反硝化速率越高。（4）各组硝酸盐氨化速率波动范围不大，但放养密度较大的C8和C10组，其硝酸盐氨化速率相对其他组较高。实验结果表明:在实验条件下，鲤鱼对沉积物-水界面的硝化和反硝化作用均有明显的促进作用，放养密度越高促进作用越明显，在沉积物中有机碳含量充足的情况下，鲤鱼的扰动可以对富营养化池塘起到很好的去氮作用。  

EFFECT ON THE BIOTURBATION OF CARPS IN DIFFERENT DENSITY ON DENITRIFICATION,NITRIFICATION AND NITRATE AMMONIFICATION RATES ON SEDIMENT-WATER INTERFACE

Carp (Cyprinus carpio) is a common freshwater fish in China, and it widely cultivates in freshwater ponds. As a benthic fish, it makes a bioturbation to the procedures on sediment-water interface, including denitrification, nitrification and nitrate ammonification. To explore the effect of different density's carps' bioturbation on denitrification, nitrification and nitrate ammonification rates, six treatments were set in this research: treatment with no fish (C0); treatments with 2, 4, 6, 8 and 10 carps in each flume (C2, C4, C6, C8 and C10). Sediment samples were collected regularly with a sediment sampler with no boundary perturbation; denitrification, nitrification and nitrate ammonifi cation rates were measured using AIT (acetylene inhibition); tracers were used to determine the depth of the carps' physical disturbance. The results showed that: (1) In the five treatments with carps, the depth of the carps' physical disturbance was mainly in 15 cm; (2) Nitrification rate in C0 was significantly faster than that in the other treatments (P0.05), while the rates in C8 and C10 which had a higher density of carps were significantly faster than that in C2, C4 and C6 (P0.05); (3) Denitrification rate was almost to 0 in C0 during the research, but in C2, C4, C6, C8 and C10, the rate got faster in the treatment with carps of higher density; (4) Nitrate ammonification rate changed a little in each treatment, but the rate in C8 and C10 was relatively faster than that in the other treatments. The present study suggested that carps' bioturbation could evidently promote denitrification, nitrification and nitrate ammonification, when there was enough organic carbon in the sediment, carps' bioturbation would have a positive affect on the procedure of removing nitrogen in eutrophic ponds.