State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2023 Apr 15;291:122300. doi: 10.1016/j.saa.2022.122300. Epub 2022 Dec 31.
Dissolved organic matter (DOM) plays key roles in species-distribution of contaminants and the biogeochemical cycle of carbon in ecosystems. Riparian zone is the representative of water-land ecotone and controls the DOM exchange between water and land. However, the variance of DOM in different landcover areas of an urban river riparian zone is unknown. In this study, fluorescence excitation-emission matrix (EEM) spectroscopy coupled with parallel factor analysis (PARAFAC) and partial least squares structural equation model (PLS-SEM) was applied to character dissolved organic matter (DOM) fractions in four types of landcover riparian areas (natural forest, artificial forest, semi-natural grassland, and cropland) of Puhe River and trace latent factors. Soil samples were collected at 0-20 cm, 20-40 cm, 40-60 cm, and 60-80 cm. The results showed that soil DOM components and humification varied between forests with grassland and cropland samples, and soil humification was obviously higher in the forest samples than that in the grassland and cropland samples. In the natural and artificial forest soils, the humic/fulvic-like were the dominant fractions of DOM, whose variations were smaller than the protein-like with soil depths. However, the tyrosine-like was the representative component in the grassland and cropland soils, whose variation was smaller than the humus substances. According to the PLS-SEM, the DOM components and humification were affected by soil physiochemical properties and DOM sources. The humification in the forest soils had a positive correlation with tryptophan-like, which derived from blended source of the autochthonous and terrigenous. Nevertheless, a positive correlation was observed between humification and humus substances, which could derive from microbial degradation of tyrosine-like, in the grassland and cropland soils. Moreover, the soil physiochemical properties were negatively related to DOM components in all soil samples, which could affect indirectly soil humification. Therefore, EEM combined with PARAFAC and PLS-SEM might be an effective method to investigate DOM fractions and trace the latent factors in different landcover areas of the riparian zone.
溶解有机质（DOM）在污染物的物种分布和生态系统碳的生物地球化学循环中起着关键作用。河岸带是水陆交错带的代表，控制着水和陆地之间的 DOM 交换。然而，城市河流河岸带不同土地覆盖区 DOM 的变化尚不清楚。本研究采用荧光激发-发射矩阵（EEM）光谱结合平行因子分析（PARAFAC）和偏最小二乘结构方程模型（PLS-SEM），对浦河四种土地覆盖区（自然林、人工林、半天然草地和耕地）的溶解有机物质（DOM）分数进行了特征分析，并追踪了潜在因素。土壤样品采集自 0-20cm、20-40cm、40-60cm 和 60-80cm 处。结果表明，森林与草地和耕地土壤样本之间的 DOM 成分和腐殖化存在差异，且森林样本的腐殖化程度明显高于草地和耕地样本。在自然和人工林土壤中，腐殖酸/富里酸样是 DOM 的主要组分，其变化幅度小于随土壤深度的蛋白质样。然而，在草地和耕地土壤中，酪氨酸样是代表性组分，其变化幅度小于腐殖质物质。根据 PLS-SEM，DOM 成分和腐殖化受土壤理化性质和 DOM 来源的影响。森林土壤的腐殖化与色氨酸样呈正相关，后者来源于混合的本地和陆源来源。然而，在草地和耕地土壤中，腐殖化与腐殖质物质呈正相关，这可能来自于酪氨酸样的微生物降解。此外，所有土壤样本中的土壤理化性质与 DOM 成分呈负相关，这可能间接影响土壤腐殖化。因此，EEM 结合 PARAFAC 和 PLS-SEM 可能是一种有效的方法，用于研究河岸带不同土地覆盖区的 DOM 分数并追踪潜在因素。
