To study the seasonal change characteristics and form composition of nitrogen and phosphorus output concentration and pollutant discharge load with rainfall characteristics at the outlet of Gufu river small watershed,the quality and quantity of water combined with natural rainfall events were monitored from January to December 2014.The results showed that the annual runoff volume of the Gufu river small watershed was 0.6×108 m3.The runoff was concentrated in raining season (from July to September),accounting for 63.9%.There was significant (P<0.01) positive correlation between the runoff flow and the annual rainfall.The annual emission of total nitrogen (TN) was 1432 t·a-1,and the emission was 853 t·a-1 during the raining season,accounting for 59.6% of annual TN emission content.The dissolved nitrogen was the main form of nitrogen emission,and the emission load of each month accounted for 55.4%-91.3% of TN.The positive correlation between the nitrate nitrogen concentration and rainfall was significant (P<0.05).The annual emission of total phosphorus (TP) was 563.1 t·a-1,and the content during the raining season accounted for 78.6% of TP annual emission content.The particle phosphorus (PP) was the main form of phosphorus emission,and the emission load of each month accounted for 41.9%-79.5% of TP.There was significant (P<0.01) positive correlation between the annual rainfall,sediment and TP,PP.The correlation between the total dissolved phosphorus concentration and rainfall was significant (P<0.05).
Keywords: Three Georges Reservoir Area; nitrogen; non-point pollution; phosphorus; small watershed.