Seasonal Variation And Output Of C,N,P In Jialing River

With industrialization and urbanization process increasing, human activities make more frequent and profound impact on water environment. Aquatic eutrophication has been a widespread ecological problems.when the Three Gorges reservoir started storage water in June 2003,the natural riverway becomes a river reservoir, water quality and safety of the Three Gorges reservoir area has becoming widespread concerned, and many scholars have did much research and analysis about water quality of the Three Gorges Reservoir.The scope of these studies focused on the main stream and backwater region of branch river, and few research on water quality of branch river,especially water quality in the Jialing River.The studies are also focused on the water quality changing and eutrophication after the Three Gorges reservoir started storage water, few studies on the concentration and forms of C,N,P,and the output flux of nutrient salt from branch river to main stream of the Three Gorges Reservoir reservoir.C, N, P is the most important nutrient salt which caused eutrophication,nutrient salt content in branch river changes in different seasons.The velocity of flow changes when the dispatching plans of Three reservoir area changes. In the dry season, the water level is higher in front of the dam, and the velocity of flow is lower. In the flood season, the water level is lower in front of the dam,and the velocity of flow is farther.Besides,in the Three Gorges reservoir area, most of the sunlight is concentrated in June to September.Therefore, the degree of eutrophication is different in different seasons.Through analysis the changes of C,N,P content in Jialing River in different seasons throughout the year and the output flux of nutrient, comparison of C, N, P content in the main stream of the Three Gorges Reservoir in different seasons to research the impact on the main stream in different seasons and discusses eutrophication of the Jialing River and its seasonal impaction of nutrient salt input to the main stream,and provides guidance for environmental protection of water quality of the Three Gorges Reservoir area.Like as Changjiang River,dissolved nitrogen(NH₃-N,NO₂-N,NO₃-N) is the main forms in Jailing River, and NH₃-N is the main form of dissolver nitrogen.The concentration of TN is high in the Jialing River,and the average concentration of TN is 1.74mg/L in 2005, which only meet the standardâ…¤, and 2.03mg/L and 2.17mg/L in 2006 and 2007, which are all beyond the standardâ…¤. The concentration of TP is low in Jailing River.and the average concentration of TP is 0.140 mg/L in 2005, which can meet the standardâ…¢, and 0.076 mg/L and 0.066 mg/L in 2006 and 2007, which all meet standardâ…¡.The proportion of TN/TP has a big fluctuation in Jialing River, and the average proportion of TN/TP is between 29.2 and 39.9. Apart from a few months, the average proportion of TN/TP is greater than 13,so the main factor of limiting biological life is P in Jialing River. When the phosphorus pollution is more serious, the water body will have the conditions for the occurrence of eutrophication, and increase the risk of eutrophication.The research focused on nutrient seasonal variation shown that the seasonal variation of concentration of NH₃-N,NO₂-N,NO₃-N were not notable, the seasonal variation of concentration of TN is dry season higer than other seasons; The seasonal variation of concentration of COD_Mn and TP in Jialing River are both flood season>normal season>dry season. There are a large number of nutrients get into Jialing river with runoff. COD_Mn, TP and water discharge had marked positive correlationship in 2005, 2006 and 2007, respectively, indicating that serious organic pollutant in Jialing river area and the dominance of diffuse agricultural runoff sources.The concentration change of diverse forms N is not notable. However the concentration change of diverse forms COD_Mn is notable, concentration of particle COD_Mn rate in total COD_Mn in flood season is higher.The seasonal variation of concentration of particle COD_Mn in flood season is higher than other seasons, and particle COD_Mn and water discharge had marked positive correlationship.The seasonal variation of concentration of Dissolved COD_Mn was not notable. Like the the concentration change of diverse forms COD_Mn. concentration change of diverse forms P is notable. PP accounted for the largest percentage of TP in flood season, ranging from 25%-95%. The concentration of PP in flood season is significant higher than dry season and shows a significant positive correlation relationship with water discharge. It shows the seasonal variation of COD_Mn and TP is mainly caused by the seasonal variation of Particle COD_Mn and PP, the nutrients that runoff brings is mainly particled in flood season, because of serious soil erosion along the Jialing River led to a large number of sand caused by entering the water body.The research focused on nutrients vertical variation showed that the vertical variation of concentration of COD_Mn, BOD₅, NH₃-N, NO₂-N, NO₃-N, TN and TP were not notable and organic pollutants were not layered.The contrast analysis, which compiared the N,P content in the Jialing river with the Changjia river, showed that the TN content of the Jialing river is slightly higher than that in the Changjian river, which indicated that the N content of the Changjia river will be increased due to the N import from Jialing river and will have some influence on Changjia river's water quality. However, the TP content in the Jialing River was far less than than in the Changjia river, which means P import from Jialing river will have some dilution effects on the TP content of the three gorges reservoir area.Seasonal variation of flux of COD_Mn,BOD₅,NH₃-N,NO₂-N,NO₃-N,TN and TP is also revealed in Jialing River, and the flux in flood season is higher than other seasons.Flux of COD_Mn, BOD₅,NH₃-N,NO₂-N,NO₃-N,TN,TP and water discharge had marked positive correlationship, respectively. Compared with COD_Mn and BOD₅ in industry pollutant load and domestic sewage load in 2005-2007, flux in Jialing River is higher prominently. Compared with NH₃-N in industry pollutant load and domestic sewage load in 2005-2007, flux in Jialing River is higher in 2005 and 2007. On the basis of the above, the water of the Three Gorges Reservoir area is effected greatly by the organic materials from the Jialing River. Furthermore, the N content in the Changjia River is higher than normal and the flow velocity of the Changjiang River will be slower when the water level reaches 175 meters. These two factors will go against the transportation and transformation of the contaminated material. So, the security of water quality of the three gorges reservoir area will be guaranteed to be safe by controlling organic materials strickly from Jialing River.