摘要:选取闽江河口潮汐湿地短叶茳芏枯落物为研究对象，通过设置不同盐度（0、5、10、15）和淹水程度（不浸没分解袋，淹水Ⅰ和持续浸没分解袋，淹水Ⅱ）等处理，分析枯落物分解过程中可溶性有机物（DOM）的含量及组成结构的紫外光谱、荧光光谱和红外光谱学等变化特征。研究结果表明，在181 d的分解过程中，枯落物可溶性有机碳（DOC）、可溶性总氮（DTN）、可溶性无机氮（DIN）和可溶性有机氮（DON）等浓度在不同盐度和淹水处理下均有显著差异（P<0.05）。盐度对DOC和DON影响不显著，但高盐组的DIN显著较低（P<0.05）；除淹水Ⅰ对照组外，各盐分处理组的芳香化指数（AI）随分解时间推移呈上升趋势。不同分解阶段对枯落物DOM组分和光谱特征有重要影响。分解前期（前89 d），淹水Ⅰ处理下，盐分升高可导致枯落物中的腐殖化指数（HIX_syn， HIX_em）降低。分解中、后期（120 d后），盐分较高条件下，腐殖质在枯落物中累积；而淹水Ⅱ处理下，盐分处理组在整个实验期内始终抑制枯落物的分解，腐殖化程度较高。淹水程度也会影响枯落物DOM的淋溶和腐殖化过程。在分解前期，淹水Ⅰ处理的AI和HIX_em显著高于淹水Ⅱ处理，而淹水Ⅱ处理下枯落物DOM较淹水Ⅰ处理更容易发生N的淋溶；分解中、后期，淹水Ⅱ处理下的厌氧环境反而抑制枯落物DOM中的腐殖质和芳香类物质析出。红外光谱分析表明，闽江河口短叶茳芏枯落物DOM中结构简单、容易分解的碳水化合物含量相对较高，但是不同淹水处理并未改变枯落物DOM的结构特征。



Abstract:In this study, we chose the withered litters of Cyperus malaccensis in Min River estuary wetlands as the research object, adopting different salinity (0,5,10,15) and flooding degree (unimmersed litterbags, flooded treatment Ⅰ and continuous immersion litterbag, flooded treatment Ⅱ) to do experiments on decomposition of the withered litters, of which its dissolved organic matter (DOM) content and structures of UV-visible spectroscopy, Fluorescence Spectroscopy, and Infrared Spectroscopy with changes in characteristics and so on. The results of this study show that the concentrations of dissolved organic carbon (DOC), total soluble nitrogen (DTN), dissolved inorganic nitrogen (DIN) and soluble organic nitrogen (DON) are of significant difference under the condition of different salinity and flooded treatment in the decomposition time (P<0.05) over 181 days of decay period. The concentrations of DOC and DON were no significant difference in different salinities, but the DIN in high salt group was significantly lower (P<0.05). The aromaticity index (AI) with different salinity treatments increased throughout the decomposition time except under the condition of flooded treatment Ⅰ. Different decomposition phases had important effects on the DOM components of C.malaccensis litters and spectral characteristics. At the earlier stage of decomposition (before 89 d), under the condition flooded Ⅰ, humification index of withered litters and debris (HIX_syn, HIX_em) was decreased when the salinity was increased. During the middle and later periods of litters decomposition (after 120 d), the higher salinity was in favor of the accumulation of humus. While under the condition of flooded treatment Ⅱ, the decomposition of litters was inhibited throughout the whole experiment period and thus the degree of humus was much higher. Water conditions also had an impact on leaching and humification of DOM of litter. The value of AI and HIX_syn were both higher in flooded Ⅰ treatments compared to flooded Ⅱ treatments at the earlier stage of litter decomposition, but more leaching of nitrogen was observed in the DOM of C. malaccensis litter under the flooded Ⅱ treatments than the flooded Ⅰ treatments in this phase. Humus and aromatic of the withered litters DOM were restrained due to the anaerobic environment under the flooded treatment Ⅱ condition during the middle and later periods of litters decomposition. Infrared Spectroscopy analysis indicates that the withered litters DOM of C. malaccensis in Min River estuary, of which the structure was simple and easy to resolve carbohydrates content which is comparatively higher. However, the structure characteristics of the withered litters DOM in C. malaccensis were unchanged under the two flooded treatments conditions.





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