Arif Gunawan, Dasapta Erwin Irawan, Achmad Darul, Rusmawan Suwarman
Groundwater phosphate pollution is an emerging environmental concern in regions facing rapid urbanization and agricultural intensification. The Surabaya-Lamongan Groundwater Basin (SLGB) in East Java, Indonesia, exemplifies such conditions, where diverse land uses and anthropogenic pressures threaten groundwater quality. This study systematically assessed phosphate contamination across a rural–urban gradient to identify spatial variability, contamination sources, and the influence of well depth and land use–land cover (LULC) on phosphate distribution. Fifty-eight groundwater samples were collected from wells representing different LULC categories and aquifer depths using a grid-based sampling design. Phosphate concentrations were analyzed by UV–Vis spectrophotometry employing the phosphomolybdenum blue method. LULC classification was derived from Landsat 7 ETM + (2000) and Landsat 8 OLI TIRS (2021) imagery. Statistical analyses including independent samples t-test, one-way ANOVA, and one-sample t-test were used to differentiate contamination patterns and evaluate exceedances of the 0.2 mg/L drinking water threshold. Phosphate concentrations were significantly higher in shallow wells than in deep wells (p < 0.05). Residential areas exhibited the highest mean value (1.107 mg/L), followed by agricultural land (0.337 mg/L), while industrial zones had the lowest (0.168 mg/L). The overall mean phosphate concentration (0.627 mg/L) exceeded the permissible limit (p < 0.001), with notable spatial variability across administrative regions. The study provides the first integrated, depth-dependent assessment of phosphate contamination in the SLGB, linking LULC dynamics with groundwater vulnerability across a rural–urban gradient. These findings underscore the need for targeted management strategies to reduce phosphate loading and ensure sustainable groundwater use in rapidly developing basins. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.
Department of Geological Engineering, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), West Java, Bandung, 40132, Indonesia; Muhammadiyah University of East Kalimantan (UMKT), East Kalimantan, Samarinda, 75124, Indonesia; Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), West Java, Bandung, 40132, Indonesia; Department of Geological Engineering, Faculty of Industrial Technology, Sumatera Institute of Technology (ITERA), Lampung, 35365, Indonesia; Professional Engineering Program, Graduate School, Padjadjaran University (UNPAD), West Java, Bandung, 40132, Indonesia