Spatial autocorrelation of nitrogenous compounds and amino acids (AAs) in wastewater-supplied urban rivers
Date
2025
Authors
Zhao, Y.
Song, Y.
Zhang, L.
Guo, C.
Huang, J.
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Journal article
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Ecological Informatics, 2025; 45(1):164-174
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Abstract
In river systems, upstream and midstream nitrogen compounds can potentially impact downstream concentrations. While the most studies have focused on the spatial and temporal variation of nitrogenous compounds and total hydrolyzed amino acids (THAAs), their spatial autocorrelation has often been overlooked. This study is the first to analyze the spatial autocorrelation of nitrogenous compounds and THAAs in water and sediment in Liangshui River, an urban river fed by wastewater in Beijing, China. Through a year-long survey, this study investigated nitrogenous compounds and THAAs from urban to rural areas. Significant spatial variations were found in nitrogenous compounds within the water (R = 0.4688, p = 0.0001) and in NH₄+-N/NO₃−-N/NO₂−-N within the sediment (R = 0.1724, p = 0.0468), while THAAs in sediments showed no significant spatial variations. This study observed relatively even contributions of nitrogenous compounds from each sampling site, suggesting homogeneous discharge patterns. Among the sites examined for sediments, Site 3 was identified as the main contributor to spatial variability (from 6.43 % to 48.25 %) in most nitrogenous compounds and THAAs.
The positive Moran's I values for all nitrogenous compounds in water and for 11 types of THAAs/NO₂−-N/NO₃−-N/TN/OrgNˢᵉᵈ in sediment indicated similar spatial distribution characteristics among successive sites. The correlation length of these nitrogenous compounds was longer than the distance between successive sites, suggesting low natural attenuation along the river. The study found that while the primary source of nitrogenous compounds in the water was adjacent contributions, the sediment's nitrogen content was mainly influenced by local sources. This study provides a new perspective for the treatment of nitrogen pollution in urban rivers, emphasizing the importance of focusing on primary sites of contribution and addressing local inputs, particularly for NH₄+-N in sediment.
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Data source: Supplementary data, https://doi.org/10.1016/j.ecofro.2024.10.004
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Copyright 2024 Published by Elsevier B.V. on behalf of Ecological Society of China.