氮添加对北方泥炭地溶解性有机质组成和生物降解性的影响

doi:10.13287/j.1001-9332.202609.047

摘要/Abstract

摘要： 在北方泥炭地中,溶解性有机质(DOM)是最活跃的有机质组分,驱动着生态系统碳周转过程。然而,氮有效性增加对北方泥炭地DOM动态的影响及其驱动机制尚不明确。本研究在大兴安岭北部连续多年冻土区泥炭地开展14年氮(0、3、6和12 g N·m^-2·a^-1)添加试验,利用三维荧光光谱技术结合室内培养试验,研究了氮添加对地表水和0~15 cm土壤孔隙水中DOM化学组成和生物降解性的影响。结果表明:随着氮添加水平增加,地表水中溶解性有机碳(DOC)和溶解性全氮(DTN)浓度呈先升后降的趋势,其中氮添加水平为6 g N·m^-2·a^-1时,DOC和DTN浓度分别比对照提高了44.8%和944.5%,而溶解性全磷(DTP)则由0.20 mg·L^-1降低至0.08 mg·L^-1。DOC∶DTP和DTN∶DTP随着氮添加水平而不断升高,意味着限制性养分由氮逐渐向磷转变。三维荧光光谱分析表明,氮添加提高了蛋白质类等相对易降解的组分比例,但降低了腐殖质组分的比例。历时42 d的室内培养试验表明,DOM生物降解性随氮添加水平增加呈先增后降的趋势。地表水在氮添加水平为6 g N·m^-2·a^-1时DOM生物降解性最高(30.3%),而土壤孔隙水在氮添加水平为3 g N·m^-2·a^-1时DOM生物降解性最高(28.8%)。逐步回归分析表明,地表水DOM生物降解性与碳质量与养分有效性显著相关,而土壤孔隙水DOM生物降解性与其芳香化程度显著相关。本研究表明,氮富集将改变北方泥炭地DOM化学组成和生物降解性,这对于理解北方泥炭地碳循环具有重要的科学意义。

关键词: 北方泥炭地, 生态化学计量, DOM化学结构, 微生物降解, 养分限制

Abstract: Dissolved organic matter (DOM) represents the most labile fractions of organic matter and drives ecosystem carbon turnover in northern peatlands. However, the effects of increased nitrogen (N) availability on DOM dynamics and the underlying mechanisms remain unclear in northern peatlands. We conducted a 14-year N addition experiment (0, 3, 6, and 12 g N·m^-2·a^-1) in a peatland located in the continuous permafrost region of the northern Greater Khingan Mountains. We examined the effects of N addition on DOM chemical composition and biodegradability in surface water and soil pore water (0-15 cm) using the excitation-emission matrix (EEM) fluorescence spectroscopy and laboratory incubation experiments. We found that dissolved organic carbon (DOC) and dissolved total nitrogen (DTN) concentrations in surface water initially increased and then decreased with the increases of N addition levels. Compared with control, N addition at 6 g N·m^-2·a^-1 had 44.8% and 944.5% higher DOC and DTN concentrations, respectively. In contrast, dissolved total phosphorus (DTP) decreased from 0.20 mg·L^-1 to 0.08 mg·L^-1 with increasing N addition levels. These changes resulted in the increases in the DOC:DTP and DTN:DTP ratios, showing the shift in the nutrient limitation status from N to P. Fluorescence analysis revealed that N addition increased the proportion of relatively labile components such as protein-like components, but reduced the proportion of humic-like components. A 42-day incubation experiment showed that DOM biodegradability initially increased and then decreased with increasing N addition levels. In surface water, N addition at 6 g N·m^-2·a^-1 had the highest DOM biodegradability (30.3%), while in soil pore water, N addition at 3 g N·m^-2·a^-1 had the greatest DOM biodegradability (28.8%). Furthermore, the stepwise regression analyses showed that DOM biodegradability correlated significantly with C quality and nutrient availability in surface water, but correlated significantly with the intrinsic aromaticity in soil porewater. Overall, our findings demonstrated that N enrichment could alter DOM chemical composition and biodegradability in northern peatlands, with implications for understanding C cycling in these ecosystems.

Key words: northern peatland, ecological stoichiometry, DOM chemical structure, microbial degradation, nutrient limitation

于乐琳, 吴璟玥, 沈辉龙, 许畅, 邹淦, 毛瑢. 氮添加对北方泥炭地溶解性有机质组成和生物降解性的影响[J]. 应用生态学报, 2026, 37(9): 3151-3158.

YU Lelin, WU Jingyue, SHEN Huilong, XU Chang, ZOU Gan, MAO Rong. Effects of nitrogen addition on the composition and biodegradability of dissolved organic matter in northern peatlands of the Greater Khingan Mountains, Northeast China.[J]. Chinese Journal of Applied Ecology, 2026, 37(9): 3151-3158.

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