The “black waters” of Malaysia: Tracking water quality from the peat swamp forest to the sea

Longitudinal water quality trends were assessed in the Tengi River system, Selangor State, Malaysia, as the water moved from a peat swamp forest, through different agricultural land uses, and finally through an urban area to the Straits of Malacca. Water draining from the peat swamp forest was dark in color due to its organic content and low in dissolved oxygen, pH, E. coli, calcium, nitrate, and ammonia. The normal diurnal pattern for water temperature was observed for the peat swamp forest drainage, but no diurnal pattern was evident in the dissolved oxygen data. The E. coli levels increased monotonically from the peat forest waters (0 colonies/100 mL) through the agricultural areas (100-2,000 colonies/100 mL) and the urban area (7,100 colonies/100 mL), and similarly pH increased along the same continuum. Dissolved oxygen increased from the peat swamp forest through the agricultural areas, but was lower in the urban-impacted reach of the Tengi River.