淡水养殖磷流层级模拟及其损失发生机制研究

Freshwater aquaculture is a critical human activity that interferes in the biogeochemical cycling of phosphorus. Excess input of phosphorus would lead to extra losses that cause eutrophication in cultured and surrounding waters. The quantification of phosphorus cycling and identifying the underlying driving forces for phosphorus loss in freshwater aquaculture play an important role in understanding the phosphorus cycle and protecting the aquatic environment. However, the phosphorus cycling mechanisms in freshwater aquaculture remains a challenge. This study takes Jiangsu Province with intensive freshwater aquaculture activities as the research area, uses the life-cycle substance flow analysis method to develop a hierarchical phosphorus cycling model and an inventory database for freshwater aquaculture after extensive literature review, field investigation and on-site monitoring, etc. Through the hierarchical modelling of phosphorus cycling in various freshwater aquaculture processes, we are able to address the characteristics of phosphorus input, harvest and loss and identify the dominant driving force(s) for phosphorus loss from freshwater aquaculture, which would lead to suggestions concerning phosphorus pollution control in freshwater aquaculture. This study will fill the blank of the hierarchical structure of phosphorus cycling in freshwater aquaculture and reveal the root causes of phosphorus loss from freshwater aquaculture. It will provide a scientific basis for eutrophication control and the sustainable development of freshwater aquaculture in river plain areas.

淡水养殖是人为干预磷循环的重要活动。磷的过量输入会增加淡水养殖磷损失，造成养殖水体及其周边水域发生富营养化。定量研究淡水养殖磷流格局及其损失发生机制对理解磷循环过程和保护水环境具有重要的基础意义。针对目前磷循环模型对淡水养殖过程研究的不足，本项目拟以淡水养殖活动密集的江苏省为研究区域，依据生命周期物质流分析原理，运用文献查阅、实地调研和现场监测等手段，建立淡水养殖磷素流动层级模型及物料清单数据库，通过对淡水养殖过程磷流路径的层级模拟，定量刻画淡水养殖磷投入、吸收、损失等特征，识别影响淡水养殖磷损失的主要因素及其影响程度，借此提出淡水养殖磷污染控制的对策建议。本研究将填补磷循环模型中淡水养殖模块的层级结构空白，揭示淡水养殖磷损失的问题根源，为平原河网地区富营养化控制战略制定和淡水养殖业可持续发展提供科学依据。

淡水养殖是人为干预磷循环的重要活动。磷的过量输入会增加淡水养殖磷损失，造成养殖水体及其周边水域发生富营养化。定量研究淡水养殖磷流格局及其损失发生机制对理解磷循环过程和保护水环境具有重要的基础意义。针对目前磷循环模型对淡水养殖过程研究的不足，本项目建立了淡水养殖磷素流动层级模型及物料清单数据库，输入端主要包括生物量投入、饵料投入、肥料投入、化学药物投入四大类，输出端主要包括生物量输出、排水、清除的底泥。通过对淡水养殖过程磷流路径的层级模拟，定量刻画了淡水养殖磷投入、吸收、损失等特征，识别了影响淡水养殖磷损失的主要因素及其影响程度。主要研究结果如下：1. 发现了池塘养殖的化肥磷占输入磷总量的比例约四分之一，说明前人研究低估了水产养殖中化肥输入的重要性。2. 发现了肥料成本只占总投入成本的不足1%，这与输入磷流的结构形成了较为鲜明的对比，推断肥料价格的低廉可能会造成淡水养殖过程中肥料的过量投入，从而导致磷损失。3. 底泥累积是最主要的磷输出途径（85%以上），其次为排水，因此，除了对池塘养殖尾水进行监管外，更需要对养殖底泥进行合理处置和养分回收。本研究填补了磷循环模型中淡水养殖模块的层级结构空白，揭示了淡水养殖磷损失的问题根源，为富营养化控制战略制定和淡水养殖业可持续发展提供了科学依据。