不同复合碳源对沉积物-水界面营养盐垂直分布特征及交换通量的影响

Effects of complex carbon sources on vertical distribution and exchange flux of dissolved nutrients at sediment-water interface

  • 摘要: 为深入探究复合碳源的净化机理,以大口黑鲈 (Micropterus salmoides) 养殖系统为实验对象,设置2个处理组,分别添加玉米皮复合碳源和水稻杆复合碳源,对照组不添加复合碳源。通过平衡式孔隙水采样 (Pore water equilibriums, Peeper) 技术采集各组沉积物-水界面垂直剖面的原位水样,分析各组营养盐的垂直分布特征,并估算沉积物-水界面的交换通量,进而研究复合碳源对沉积物-水界面氮迁移转化的影响。结果表明:1) 各组沉积物-水界面各营养盐均具有明显的垂直分布规律,除铵态氮 (NH4 +-N)、总氮 (TN) 外,其他营养盐的浓度随深度增加呈下降趋势。2) 在大口黑鲈养殖系统沉积物中,硝态氮 (NO3 -N) 是主要的内源释放营养盐;相比对照组,2组复合碳源均促进了沉积物中NH4 +-N的释放;此外,玉米皮碳源减缓了NO3 -N、亚硝态氮 (NO2 -N) 和磷酸盐 (PO4 3−-P) 的释放,水稻杆碳源的影响不显著。3) 添加复合碳源促进了水体营养盐的去除,相比水稻杆碳源,玉米皮碳源对TN、PO4 3−-P和化学需氧量 (COD) 的去除率更高,分别为73%、53%和48%。综上,添加复合碳源能够影响营养盐垂直分布特征和沉积物-水界面的扩散通量,其中玉米皮碳源可减缓沉积物中营养盐的释放,且具有较好的水体净化效果。

     

    Abstract: In order to investigate the purification mechanism of composite carbon source, taking largemouth bass (Micropterus salmoides) breeding system as the experimental object, we added the treatment group with composite carbon source of corn husk and composite carbon source of rice straw, but did not add the control group with composite carbon source, and then collected the in situ water samples from the vertical profiles of each group of the sediment-water interface by using with the Peeper (Pore water equilibriums) technique, so as to analyze the vertical distribution of nutrient salts in each group and to estimate the exchange fluxes at the sediment-water interface, investigating the effects of the composite carbon sources on the nitrogen transport and transformation at the sediment-water interface. The results show that: 1) Each group of nutrient salts at the sediment-water interface had a strong vertical distribution pattern, except for ammonium nitrogen (NH4 +-N) and total nitrogen (TN), while the other nutrient salts showed a decreasing trend with depth. 2) NO3 -N was the main endogenously released nutrient salts in the sediments of the largemouth bass aquaculture system. Compared with the control group, the two groups of carbon sources both promoted the release of NH4 +-N in the sediments. The corn husk carbon source slowed down the release of nitrate nitrogen (NO3 -N), nitrite nitrogen (NO2 -N), and phosphate (PO4 3−-P), and the effect of the rice straw carbon source was insignificant. 3) The addition of the composite carbon source promoted the nutrient salts removal from the water body. Compared with the rice straw carbon source, the corn husk carbon source had higher TN, PO4 3−-P and chemical oxygen demand (COD) removal rates of 73%, 53% and 48%, respectively. In conclusion, adding composite carbon sources affects the vertical distribution characteristics of nutrient salts and diffusion fluxes at the sediment-water interface; the corn husk carbon source slowed down the release of nutrient salts from the sediment and had a better effect on water purification.

     

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