Research article Amplified impacts of human activities: Non-linear responses of riverine microbial communities to distribution of land use Zhenyu Zhang a,f , Junhao Tang b,c , Long Wang b,* , Chongchong Zhu d,** , Qian Xun g , Daniel Rosado e,f a School of Geographical Sciences, Fujian Normal University, Fuzhou, 350007, China b School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China c School of Life Sciences, Guangzhou University, Guangzhou, 510006, China d Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, School of Geography, Nanjing Normal University, Nanjing, 210023, China e Department of Chemical and Environmental Engineering, University of Seville, 41092, Sevilla, Spain f Department of Hydrology and Water Resources Management, Institute for Natural Resource Conservation, Kiel University, 24118, Kiel, Germany g RISE Research Institutes of Sweden, Brinellgatan 4, Borås, 50462, Sweden A R T I C L E INFO Keywords: Land use Riverine microbial communities Urbanized watershed Geographical detector model ABSTRACT Rapid global urbanization poses considerable ecological risks to freshwater systems, notably leading to sub- stantial reductions in microbial communities. To assess the impacts of human activities on these communities, we applied the high-throughput amplicon DNA sequencing to examine spatial variations in riverine microbial communities within an urbanized watershed. Coupled with the Geographical Detector Model, the effects of the land use were identified across the watershed. Results show that microbial communities were closely linked to the human-impacted land use patterns. The upstream region, dominated by forest cover (71%), exhibited the highest microbial population (3384 OTUs), whereas the urbanized downstream outlet (91% urban land) showed the lowest microbial population (471 OTUs). Additionally, the spatial distribution of the human-impacted land use appears to abruptly alter microbial pathways along the river. The spatial threshold effect of human-impacted land use is indicated by a Moran’s I value exceeding 0.80. Notably, a 300-m buffer zone around different land uses seems to significantly influenced sediment microbial communities. Besides, the influence of land use on microbial communities is intensified by spatial drivers. For instance, agricultural land use was found to impact riverine Parcubacteria communities, with factor detector values increasing by over 30% in 400–500 m buffer zones. These findings provide new insights into the complex relationship between human activity and riverine microbial communities, highlighting important implications for ecosystem management in rapidly urbanization regions. 1. Introduction Rapid global urbanization presents a significant ecological risk to freshwater systems by increasing nutrient, heavy metals, and other pollutant loads, leading to a substantial loss of biodiversity in aquatic communities (Li et al., 2018; Zhang et al., 2024a). As the foundational biotic element of these systems, microbes serve as primary and sec- ondary producers by regulating critical biogeochemical cycles in the riverine systems. In particular, microbial communities in sediments act as the primary drivers of essential biochemical cycles, such as those of carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, and various metals, making them integral to the freshwater ecosystem’s function- ality (Dang et al., 2021; Fan et al., 2024). As key indicators of ecological risk in watersheds systems, sediment microbial communities are highly sensitive to changes in physicochemical properties at the sediment-water interface, where they influence pollutant pathways by altering their distribution, transport, and fate within this complex dy- namic system (Pan et al., 2022; Zhang et al., 2024b). So far, our knowledge of how sediment microbial communities respond to human-induced changes is still limited (Liao et al., 2019; Hu et al., * Corresponding author. School of Environmental Science and Engineering, Guangzhou University, Guangzhou, 510006, China. ** Corresponding author. E-mail addresses: zhangzy@fjnu.edu.cn (Z. Zhang), 32214100012@e.gzhu.edu.cn (J. Tang), wlong@gzhu.edu.cn (L. Wang), 201301035@njnu.edu.cn (C. Zhu), qian.xun@ri.se (Q. Xun), djrosado@us.es (D. Rosado). Contents lists available at ScienceDirect Journal of Environmental Management journal homepage: www.elsevier.com/locate/jenvman https://doi.org/10.1016/j.jenvman.2024.123937 Received 5 August 2024; Received in revised form 15 November 2024; Accepted 27 December 2024 Journal of Environmental Management 373 (2025) 123937 Available online 4 January 2025 0301-4797/© 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.