The Suquía River, the largest urban river in Córdoba (Argentina), has been severely polluted for decades. Actions must be taken to restore its environmental quality by managing riparian zones for increased water-self purification. The current study aimed to characterize organic matter (OM) dynamics and humic substances (HS) spectrochemical properties along the lower-middle basin of the Suquía River. Riparian soil (0–20 cm) and sediment (0–10 cm) samples were collected from a reference location (S1) and four polluted sites (S2–S5) during a low-flow period. The contents of soil and sedimentary OM and HS fractions were analyzed by wet oxidation, as well as HS Fourier transform infrared (FT-IR) and ultraviolet–visible (UV–Vis) spectrochemical properties. The OM and HS fractions from riparian soil were high upstream of Córdoba City (S1 and S2, 50.2–50.4 g/kg OM) and within a 50 km downstream location (S5, 30.9 g/kg OM) owing to a surplus of fresh plant biomass-carbon (C) inputs. Highly heterogeneous sediment samples did not show any significant differences among sites (P > 0.05). The lowest values of the ratio of absorbances at 465 and 665 nm (E₄/E₆) (1.78) and the Δ log K (0.15) coefficient (a measure of HS maturity degree) were obtained downstream of Córdoba City, for both riparian soil and sediment, indicating that HS were enriched by more condensed aromatic structures within highly degraded portions of the river. All samples exhibited similar IR spectra, implying overlapping recalcitrant-C structures at the functional group level, but with different absorbance intensity. Data from the current study constitute a baseline for understanding the chemical nature of HS from sediment and riparian soil along the Suquía River and can be used as a reference for future studies tracking OM compositional changes over time.

Suquía河是科尔多瓦（阿根廷）最大的城市河流，几十年来一直受到严重污染。必须采取措施，通过管理河岸带以提高水的自净性来恢复其环境质量。目前的研究旨在表征苏基亚河中下游盆地有机物（OM）动力学和腐殖质（HS）光谱化学性质。在低流量时期，从参考地点（S1）和四个污染地点（S2–S5）收集河岸土壤（0–20 cm）和沉积物（0–10 cm）样品。通过湿式氧化，HS傅立叶变换红外光谱（FT-IR）和紫外可见光谱（UV-Vis）的光谱化学特性分析了土壤和沉积物OM和HS组分的含量。河岸土壤中的OM和HS分数在科尔多瓦市上游较高（S1和S2，50.2–50。4 g / kg OM）和下游50公里以内的位置（S5，30.9 g / kg OM），这是由于新鲜植物生物量碳（C）投入过多。高度异质的沉积物样本在站点之间没有显示任何显着差异（P  > 0.05）。最低吸光度比在465和665 nm（E ₄ / E ₆）（1.78）和Δ在河岸土壤和沉积物上都获得了科尔多瓦市下游的log K（0.15）系数（衡量HS成熟度的指标），表明HS在河道高度退化的部分中被更多冷凝的芳香结构所富集。所有样品均表现出相似的红外光谱，这意味着官能团水平上的顽固性C结构重叠，但吸收强度不同。来自当前研究的数据构成了了解Suquía河沿岸沉积物和河岸土壤中HS的化学性质的基线，可以用作将来跟踪OM组成变化的研究的参考。