Water quality in-situ purification method in river estuary

A water quality in-situ purification method in river estuary relates to a water quality purification method in river estuary, especially relates to river estuary of convergence of lakes and rivers. A deposition pond, a aeration oxidation zone, a facultative pond and a floating island biological purification zone are disposed along rivers flowing into the lake direction in turns in river estuary of the horn-mouth shape region where watercourse crossing rivers and lakes, the method is: a, upstream polluted river water flows into the deposition pond for sedimentation, anaerobic decomposition and plant absorption; b, deposited river water flows into the aeration oxidation zone in order for increasing oxygen content; c, then the river water flows from the aeration oxidation zone into the facultative pond for degradation; d, degraded river water flows into the floating island biological purification zone at last, then the polluted water flows into lake by purification treatment. The invention uses in-situ purification method to process river water, no occupation of watercourse side land, resolving problem of rare land resource in river estuary and difficult to build water quality purification establishment. Key point of the invention provided water quality purification is intensifying absorption of natural hydrophyte and metabolism of microorganism for degrading pollutant in water, the water quality purification effect is obvious and brings no secondary pollution.