渔塘种稻对塘体沉积物-水界面氮磷迁移转化的影响及其作用机制

Rice is an important cereal crop in China, and also has great ability in the accumulation of water nutrients. Therefore, coupling of the rice cropping system and pond culture system could have great potential for ecological restoration of aquaculture pond eutrophication and achieving a win-win situation of rice and fish production. However, the mechanism is still unclear that how the rice mitigate the nutrients (nitrogen and phosphorous) in the water of aquaculture pond. The key process regulating the contents of nutrients in the water of aquaculture pond is the migration and transformation of nutrients at sediment-water interface. So the impacts of rice on this process should be the main pathway mitigating the nutrients in the water of aquaculture pond. Therefore, this project plan to take the rice-fish co-culture new mode (planting rice in aquaculture pond) as an example, and conduct a field study to investigate the impacts of rice planting on the environment factors, the forms of nitrogen and phosphorous, and the fluxes of these two nutrients at sediment-water interface. And the main pathway and mechanism of rice production on the nutrients migration and transformation at the sediment-water interface will be elucidated. These results will increase our knowledge on the mechanism of rice mitigating the nutrients in the water of aquaculture pond, and also will provide good reference for the investigation and application of new farming models which can be both environmentally friendly and win-win of fish and rice production.

水稻是我国重要的粮食作物，对水体养分也具有显著吸收能力。将稻作系统与池塘养殖进行生态耦合，对于减轻水体富营养化和“促养增粮”具有巨大应用潜力。沉积物-水界面氮磷迁移转化是影响养殖池塘水体养分的核心过程，稻作系统主要通过对这一过程的影响来净化水体。然而，目前对此过程的作用机制仍有待进一步深入研究。为此，本项目以水稻-水产生态耦合新模式——渔塘种稻为例，通过小区实验研究渔塘种稻对养殖塘沉积物-水界面微环境、氮磷赋存形态以及扩散通量的影响，探讨水稻对沉积物-水界面氮磷迁移转化的作用途径，分析其中的作用机制。以增加对水稻净化水质作用机制的科学认识，为环境友好型“促养增粮”模式的探索与应用提供理论依据。

集约化精养池塘对水体的富营养化污染是目前池塘养殖可持续发展面临的重要问题。将稻作系统与池塘养殖进行生态耦合，对减轻水体富营养化和促养增粮具有巨大应用潜力。但是目前对水稻消减水体养分的作用机制还缺乏深入研究。沉积物-水界面养分迁移转化是影响水体养分含量的重要过程。为此，本项目重点针对养殖池塘沉积物-水界面氮磷迁移转化过程，研究渔塘种稻对沉积物-水界面微环境、氮磷赋存形态以及扩散通量等界面特征的影响。以增加对水稻消减水体养分的作用机制的科学认识。经过三年的研究，取得了以下主要结果：1）水稻种植显著降低了养殖池塘水体富营养化程度，改善了水质。与单养鱼相比，稻鱼共作显著降低了水体总氮、总磷、氨态氮和硝态氮含量。稻鱼共作池塘水体总氮和总磷含量可以达到国家I级排放标准。2）渔塘种稻对沉积物-水界面O2、Eh和pH剖面分布存在显著影响。与单养鱼池塘相比，稻鱼共作可增加沉积物-水界面O2浓度和渗透深度，增加界面附近Eh值，降低pH值。3）池塘种稻能够促进底泥中有机态氮磷的矿化，增加无机态氮磷的比例。水稻生长吸收显著降低了底泥中氨态氮的含量，但是无机氮在总氮中所占比例却呈增加趋势。水稻种植也促进了底泥中有机磷向无机磷的转化，HCl-P和NH4Cl-P的比例呈增加趋势。4）池塘种稻显著降低了沉积物-水界面NO3--N、NO2--N和NH4+-N释放通量，但对DIP通量没有显著影响。5）渔塘种稻能够显著降低养殖水体N2O和NH3排放。与单养鱼池塘相比，黄颡鱼和青虾种稻池塘N2O排放分别降低83.4%和143.4%； NH3挥发分别降低29.7%和28.9%。 6）水稻对池塘养分具有显著的富集作用。黄颡鱼塘水稻对氮、磷的总富集量分别达到14.7 g m-2和1.95 g m-2； 青虾塘水稻对氮、磷的总富集量分别达到8.9 g m-2和1.35 g m-2。上述结果可以丰富我们对池塘种稻模式中养分循环过程的科学认识，为新型稻鱼共作模式的探索与应用提供理论依据。通过三年的研究，目前已发表学术论文3篇，其中SCI论文1篇。获得国家专利3项。制定农业部行业标准1项。