Phosphorus distribution in Haihe River of Tianjin City

The monitoring results and distribution characteristics of orthophosphate,total dissolved phosphorus(TDP) and total phosphorus(TP) in 29 water samples taken from the mainstream of the Haihe River and some tributaries(the Beiyunhe River,the Ziyahe River and the Nanyunhe River) show that TP in the main stream of the Haihe River ranges from 0.4 to 3.5 mg/L,thus failing to meet the grade Ⅴ standard of Environmental quality standards for surface water(GB38382002).The concentrations of orthophosphate and TDP in the mainstream are,respectively,0.09-0.75 mg/L and 0.24-1.42 mg/L.The concentrations of TP,orthophosphate and TDP in the tributaries are,respectively,0.2-5.0 mg/L,0.01-3.63 mg/L and 0.12-4.16 mg/L.The content of phosphorus at most cross sections of the tributaries is higher than that in mainstream.TDP is the dominant part of TP due to the low concentration of suspended sediments in the Haihe River in Tianjin City.