We investigated the fluorescent dissolved organic matter (FDOM) composition in two watersheds with variable land cover and wastewater infrastructure, including sanitary sewers and septic systems. A four-component parallel factor analysis model was constructed from 295 excitation–emission matrices recorded for stream samples to examine relationships between FDOM and geospatial parameters. The contributions of humic acid- and fulvic acid-like fluorescence components (e.g., C1, C2, C3) were fairly consistent across a 12 month period for the 27 sampling sites. In contrast, the protein-like fluorescence component (C4) and a related ratiometric wastewater indicator (C4/C3) exhibited high variability in urban tributaries, suggesting that some sites were impacted by leaking sewer infrastructure. Principal component analysis indicated that urban areas clustered with impervious surfaces and sanitary sewer density, and cross-covariance analysis identified strong positive correlations between C4, impervious surfaces, and sanitary sewer density at short lag distances. The presence of wastewater was confirmed by detection of sucralose (up to 1,660 ng L^–1) and caffeine (up to 1,740 ng L^–1). Our findings not only highlight the potential for C4 to serve as an indicator of nearby, compromised sanitary sewer infrastructure, but also suggest that geospatial data can be used to predict areas vulnerable to wastewater contamination.

中文翻译：

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城市流域荧光溶解有机物的地理空间变化：与土地覆盖和废水基础设施的关系

我们调查了两个土地覆盖和废水基础设施（包括生活污水管道和化粪池系统）可变的流域中的荧光溶解有机物 (FDOM) 组成。根据为流样本记录的 295 个激发发射矩阵构建了四分量并行因子分析模型，以检查 FDOM 和地理空间参数之间的关系。 27 个采样点的 12 个月内，腐殖酸和黄腐酸类荧光成分（例如 C1、C2、C3）的贡献相当一致。相比之下，类蛋白质荧光成分 (C4) 和相关的比率废水指标 (C4/C3) 在城市支流中表现出较高的变异性，表明某些地点受到下水道基础设施泄漏的影响。主成分分析表明，城市地区不透水表面和生活污水管密度聚集，交叉协方差分析发现，C4、不透水表面和生活污水管密度之间在短滞后距离上存在很强的正相关关系。通过检测三氯蔗糖（高达 1,660 ng L ^–1）和咖啡因（高达 1,740 ng L ^–1 ）证实废水的存在。我们的研究结果不仅强调了 C4 作为附近受损的下水道基础设施指标的潜力，而且还表明地理空间数据可用于预测容易受到废水污染的区域。