渔塘种稻对养殖池塘氮污染的消减效应及作用机制研究

The nitrogen pollution caused by intensive culture was a serious problem influencing the sustainable development of pond aquaculture. There is a great potential to reduce the nitrogen pollution by coupling the rice cultivation with pond culture. However, it is still unclear that how the rice to reduce the nitrogen pollution in rice-fish co-culture pond. Therefore, this project mainly focused on the nitrogen pollution in aquaculture pond, and plan to investigate the impact of rice planting on the nitrogen transformation, migration and allocation in different pond (fish, crab, and shrimp) by using 15N isotope labelled experiment. Furthermore, field and pot experiments were conducted to investigate the effect of rice on the key processes, such as the food intake and nitrogen excretion of aquaculture animals, the nitrogen release from sediment caused by bioturbation, and the gas loose of nitrogen. And the main pathway, mechanism and key inflation factors of rice on the mitigation of nitrogen pollution in aquaculture pond will be elucidated. These results 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.

集约化精养池塘对水体和大气环境的氮污染日益严重，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，对减轻池塘养殖的环境污染和“促养增粮”具有巨大应用潜力。但是目前对水稻如何消减养殖池塘氮污染的作用机制还缺乏深入研究。为此，本项目重点针对养殖池塘的氮污染问题。采用15N同位素示踪技术，研究水稻种植对不同类型养殖池塘（鱼、蟹、虾）饲料氮转化、迁移和分配特征的影响；通过小区和盆栽模拟试验，研究水稻对水产动物摄食与氮排泄、底泥生物扰动氮释放、以及底泥和水体氮素气态散失等关键过程的影响。解析水稻对养殖池塘氮污染消减途径、作用机制和关键影响因素。以期能为环境友好型“促养增粮”模式的探索与应用提供理论依据。

集约化池塘养殖对于保障我国淡水水产品供给至关重要。但是其对周边水体和大气环境的氮污染也日益严重。将稻作系统与池塘养殖进行生态耦合，有利于减轻池塘养殖的环境污染和“促养增粮”。但是目前对水稻如何消减养殖池塘氮污染的作用机制还缺乏深入研究。本项目围绕三种典型池塘种稻模式（青虾-稻、黄颡鱼-稻和螃蟹-稻），综合采用小区试验、盆栽模拟实验和15N同位标记试验等方法，研究了渔塘种稻对养殖池塘氮污染的消减效应，深入解析了水稻对水产动物摄食与氮排泄、底泥生物扰动氮释放、以及底泥和水体氮素气态散失等关键过程的影响及作用机制。主要取得以下结果：1）水稻种植对青虾、黄颡鱼、和螃蟹三种养殖池塘中水产动物的氮收获量没有显著影响。但显著降低了水体、底泥中氮残留量，显著降低了气态氮损失量。水稻种植有利于吸收利用池塘系统中冗余在水体和底泥中的氮，减少养殖尾水氮排放和气态氮排放，提高系统氮利用率。2）种植水稻显著增加鱼粗蛋白含量，但对其他生长性能指标以及消化酶活性、氮排泄速率没有显著影响。3）由于水稻根系对底泥的固持作用以及水稻茎叶对水体中悬浮颗粒物的吸附作用，渔塘种稻可以显著降低黄颡鱼和螃蟹生物扰动导致的沉积物再悬浮及再悬浮过程中的氮释放。水稻对鱼、蟹生物扰动的抑制效应随养殖密度的增加而降低。增加水稻种植密度可以增强水稻的抑制效应。4）渔塘种稻显著降低池塘水稻种植区及养殖沟氨挥发和N2O排放。投喂率和饲料蛋白含量的增加会削弱水稻对养殖池塘气态氮排放的消减效应。籼稻品种对N2O的消减效应强于粳稻。上述结果可以丰富我们对水稻消减养殖池塘氮污染的科学认识，为稻鱼共作模式的探索与应用提供理论依据。