Water quality assesment of Pengambang River, Pekanbaru City, Riau Province, Indonesia using pollution index (PI)Yuliati Yuliati, Eni Sumiarsih, Adriman Adriman, Efawani Efawani and Daniel Poima Saputra NapitupuluBIO Web Conf., 74 (2023) 05003DOI: https://doi.org/10.1051/bioconf/20237405003