While dissolved organic matter (DOM) is an important indicator of water quality, land use and land cover (LULC) of watersheds define the source, quality, and quantity of DOM delivered to a waterbody. This study examined the influence of various LULC classes in the spatial distribution of DOM in 41 lakes across the state of Mississippi. To scale the influence of LULC classes on DOM distribution, we have classified 41 lakes into five clusters based on DOM compositions determined by parallel factor analysis. Four major DOM compositions including terrestrial humic-like (C1), microbial humic-like (C2), soil-derived humic-like (C3), and tryptophan-like or tyrosine like (C4) components were identified. Higher amounts of terrestrial humic-like and soil-derived humic-like DOM compositions were observed in lakes within watersheds dominated by forested, barren, wetlands, or agricultural areas with exposed unconsolidated soil. Higher amounts of microbial humic-like composition were observed in lakes surrounded by hay/pasture, rangeland, and urbanized areas. Additionally, protein-like DOM and ammonia were more enriched in larger lakes, indicating the influences of photochemical reactions. High amounts of forested areas and higher concentrations of terrestrial humic-like DOM composition were identified in all lakes suggesting forested areas in the watershed as the principal source of DOM in Mississippi lakes.

中文翻译：

---

美国密西西比州 41 个湖泊中溶解有机质空间变化的土地利用和土地覆盖控制

虽然溶解有机物 (DOM) 是水质的重要指标，但流域的土地利用和土地覆盖 (LULC) 定义了输送到水体的 DOM 的来源、质量和数量。本研究检查了各种 LULC 类别对密西西比州 41 个湖泊中 DOM 空间分布的影响。为了衡量 LULC 类别对 DOM 分布的影响，我们根据并行因子分析确定的 DOM 组成将 41 个湖泊分为五个集群。确定了四种主要的 DOM 成分，包括陆地腐殖质样 (C1)、微生物腐殖质样 (C2)、土壤衍生腐殖质样 (C3) 和色氨酸样或酪氨酸样 (C4) 成分。在以森林为主的流域内的湖泊中观察到较高量的陆地类腐殖质和土壤衍生的类腐殖质 DOM 成分，裸露的松散土壤的贫瘠、湿地或农业区。在被干草/牧场、牧场和城市化地区包围的湖泊中观察到更多的微生物类腐殖质成分。此外，蛋白质样 DOM 和氨在较大的湖泊中更富集，表明光化学反应的影响。在所有湖泊中都发现了大量的森林区域和较高浓度的陆地腐殖质类 DOM 成分，表明流域中的森林区域是密西西比湖中 DOM 的主要来源。表明光化学反应的影响。在所有湖泊中都发现了大量的森林区域和较高浓度的陆地腐殖质类 DOM 成分，表明流域中的森林区域是密西西比湖中 DOM 的主要来源。表明光化学反应的影响。在所有湖泊中都发现了大量的森林区域和较高浓度的陆地腐殖质类 DOM 成分，表明流域中的森林区域是密西西比湖中 DOM 的主要来源。