• 关键词：藻屑  沉积物-水界面  氮、磷营养盐  溶解性有机质

• 基金项目：国家自然科学基金面上项目（No.41471075，41171366）；国家水体污染控制与治理科技重大专项项目（No.2017ZX07603-005）；江苏省高校水处理技术与材料协同创新中心项目

• 王亚蕊
• 1. 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2. 中国科学院大学, 北京 100049

• 陈向超
• 1. 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2. 中国科学院大学, 北京 100049

• 陈丙法
• 1. 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008;2. 中国科学院大学, 北京 100049

• 钟继承
• 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008

• 柯凡
• 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008

• 陈开宁
• 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008

• 冯慕华
• 中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008

• 摘要：为探索不同密度藻屑堆积对沉积物-水界面污染物的释放效应，设置了对照组（无藻屑添加）、2个藻屑添加组（分别为1倍组（加入0.06 g干藻，约6 g·m^-2，以干重计）、20倍组（加入1.2 g干藻，约120 g·m^-2，以干重计）），于（16±1）℃避光培养.结果表明，实验前4 d，20倍组藻屑分解耗氧剧烈并释放出大量溶解性有机质（DOM）及氮、磷营养盐.其中，溶解氧（DO）浓度迅速下降至1.4 mg·L^-1以下，上覆水中类色氨酸类物质荧光强度在第4 d最高（0.8 RU）且高于空白组，对荧光强度的贡献比例高达51.7%，为DOM的主要成分，说明藻屑分解释放大量类色氨酸物质.释放的溶解性无机氮（DIN）、溶解性总磷（DTP）以氨氮（NH₄⁺-N）、正磷酸盐（PO₄^3--P）为主要形态.随后实验阶段上覆水中S_R值、E₂₅₀/E₃₆₀值降低，E₂₅₃/E₂₀₃值增加，说明藻屑在降解过程中腐殖化程度逐渐增加，取代基种类减少，导致释放的DOM以类腐殖质为主.因此，20倍组类色氨酸类物质逐渐被降解，导致荧光强度逐渐降低，类腐殖质荧光强度增加，对荧光强度的贡献比例高达62.7%.而对照组与1倍组污染物释放培养期间无显著性差异，DOM及氮、磷营养盐释放浓度均低于20倍组.因此，120 g·m^-2藻屑密度堆积情况下可造成水体明显缺氧至厌氧，导致大量氮、磷营养盐及溶解性有机物释放至上覆水中，成为水体富营养化的重要营养源.

• Abstract：In order to decipher the influence of algal-debris densities on the release of pollutants from sediments, two treatments, x1 treatment (adding 0.06 g dry algal-debris, about 6 g·m^-2) and×20 treatment (adding 1.2 g dry algal-debris, about 120 g·m^-2), were performed at light-avoiding condition (16±1)℃, together with the blank control (without algal-debris). The results show that the decomposition of algal-debris consumed dissolved oxygen (DO) drastically so as to release the large amounts of dissolved organic matter (DOM) and nutrients in the first four days. On the fourth day of experiment, the concentration of DO in×20 treatment decreased below to 1.4 mg·L^-1 and tryptophan-like fluorescence intensity (0.8 RU) of DOM reached highest, accounting for 51.7% of PARAFAC components, which were higher than that of control, indicating the release of tryptophan-like OM due to algal-debris decomposition. Ammonia nitrogen (NH₄⁺-N) and phosphate (PO₄^3--P) were the main forms of dissolved inorganic nitrogen (DIN) and dissolved phosphorus (DTP), respectively. During the following incubation, the decrease of S_R and E₂₅₀/E₃₆₀, and the increase of E₂₅₃/E₂₀₃ illustrate that the humification of algal-debris increased gradually and substituent species decreased, resulting in the dominant release of humic-like DOM. Therefore, the decrease of tryptophan-like fluorescence intensity and the increase of the humus fluorescence intensity suggest the degradation of tryptophan-like OM and the release of humus, resulting that humus contributes to 62.7% of fluorescence in×20 treatment. There is insignificant difference in the release of DOM and nutrients between×1 treatment and the control. In general, the addition of×20 algal-debris to sediment can cause oxygen deficient or even anaerobic condition in water body, and advance the release of nutrients and DOM from sediment-water interface to overlying water, which become important interior loading of eutrophication.

• Key words：algal-debris  sediment-water interface  nitrogen and phosphorus nutrients  dissolved organic matter

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