Abstract:

Environment pollutants and carbon emissions are highly homologous, and it is feasible to simultaneously control both of them. To address the release of nitrogen, phosphorus, and carbon emissions during algae decomposition in eutrophic lakes, this study conducted column simulation experiments to analyze the impact of algae salvage on nitrogen and phosphorus concentrations and greenhouse gas (CO₂, CH₄ and N₂O) fluxes, and assessed the effectiveness of algae salvage in controlling pollutants and reducing carbon emissions in eutrophic lakes. The results indicated that, the removal of algal biomass by 33%, 66%, and 99% resulted in a decrease in total nitrogen by 26.1%, 35.4%, and 53.8%, and total phosphorus by 50.9%, 72.9%, and 78.2%, respectively. Similarly, the removal of algal biomass resulted in decreases in CO₂ fluxes by 26.7%, 39.4%, and 54.5%, CH₄ fluxes by 58.1%, 89.0%, and 91.5%, and N₂O fluxes by 71.3%, 90.4% and 87.5%, respectively. Furthermore, the removal of algal biomass prevented water dissolved oxygen depletion, changed the oxidation-reduction conditions, regulated the carbon and nitrogen decomposition process, and reduced the proportion of CH₄ and N₂O in greenhouse gas emissions. Under the low, medium, and high intensities of algal biomass removal, the proportion of CH₄ derived CO₂-eq decreased by 6.4%, 2.2%, and 2.2%, respectively, while the proportion of N₂O derived CO₂-eq decreased by 6.1%, 2.6%, and 4.6%, respectively, leading to a further reduction in total CO₂-eq emissions. Under the low, medium, and high intensities of algal biomass removal, the CO₂-eq emission decreased by 35.9%, 51.4%, and 62.7%, respectively. The removal of algal biomass decreased nitrogen and phosphorus concentrations, and reduced greenhouse gas fluxes, thus achieving co-control of pollutants and carbon emissions in eutrophic lakes. These findings offer useful insights for future comprehensive assessments of the ecological benefits of algae salvage in eutrophic lakes.

Key words: lake, eutrophication, algae salvage, pollutant and carbon emission control, nitrogen and phosphorus, greenhouse gas

摘要：

环境污染物与温室气体排放具有高度同根同源特征，在环境治理过程中减污和降碳方面具有协同推进的潜力。针对富营养化湖泊藻源性生物质分解带来的氮磷二次释放和温室气体排放问题，利用水-沉积物柱实验体系，通过人为移除藻源性生物质的方式模拟了不同蓝藻打捞强度，分析了不同藻源性生物质移除强度对水体氮磷水平与温室气体（CO₂、CH₄和N₂O）排放通量的影响，评估了蓝藻打捞削减污染水平和控制碳排放效果。结果表明，当藻源性生物质移除33%（低强度）、66%（中强度）、99%（高强度）时，总氮分别下降26.1%、35.4%、53.8%，总磷分别下降50.9%、72.9%、78.2%，CO₂释放通量分别下降26.7%、39.4%、54.5%。CH₄释放通量分别下降58.1%、89.0%、91.5%，N₂O释放通量分别下降71.3%、90.4%、87.5%。此外，藻源性生物质的移除避免了水体溶解氧耗竭，改变了氧化还原条件，调控了碳氮分解过程，降低了高CO₂当量（CO₂-eq）的CH₄和N₂O在温室气体排放中的占比。在低、中、高移除强度下，CH₄的CO₂-eq占比分别为6.4%、2.2%、2.2%，N₂O的CO₂-eq占比分别为6.1%、2.6%、4.6%，进一步降低总CO₂-eq释放通量。在低、中、高移除强度下，CO₂-eq释放通量分别下降35.9%、51.4%和62.7%。藻源性生物质移除不仅直接削减了水体氮磷水平，降低了温室气体排放通量，实现了减污降碳有效协同。该研究对于富营养化湖泊蓝藻打捞环境效益综合评估具有重要借鉴意义。

关键词: 湖泊, 富营养化, 蓝藻打捞, 减污降碳, 氮磷, 温室气体