| As the water source of the"Luanhe-Tianjin Diversion Project",Panjiakou and Daheiting reservoirs play important roles in the synergetic development of the Beijing-Tianjin-Hebei region.The water quality in the reservoir is directly related to the safety of drinking water and the health of the people in the water receiving area.Based on the historical water quality data of Panda Reservoir and the investigation of waterin July 2016,the changes and present situation of water environmental factors are analyzed in this paper.The results show that the total nitrogen of reservoir is basically in the inferior V level.In recent years,the total phosphorus is in the level of?to V,rising in recent years,reaching the historical high in 2016,ammonia nitrogen is in the level of class?to class?,and the change is relatively small in recent years.Nitrate nitrogen generally accords with the national drinking water source standard,and in recent years,the trend of decline is obvious,and in 2016 it reached the lowest point in history.The spatial distribution of total nitrogen and nitrate nitrogen in Panjiakou reservoir is obviously higher than that in Daheting reservoir.Ammonia nitrogen and total phosphorus were significantly higher in Daheting Reservoir than in Panjiakou Reservoir.The surface sediment of the reservoirs was investigated in July 2016,in order to illuminate the sediment nutrients?nitrogen,phosphorus and organic matter?contaminant status and the spatial pattern.The results showed that the average contents of total nitrogen?TN?,total phosphorus?TP?and organic matter?OM?were 1648.71 mg·kg-1,2790.89 mg·kg-1and 12.49%,respectively.TN contents were similar in Panjiakou and Daheiting reservoir,and TP content in Daheiting Reservoir was slightly higher than that in Panjiakou reservoir.Pearson linear correlation analysis showed that TN and TP were both significantly correlated with OM?p<0.05?,while TN had no significant correlation with TP?p>0.05?.This indicated that OM contributed a lot to nitrogen and phosphorus,but nitrogen and phosphorus might have different sources.C/N ratio?mean value was 29.08?implied that OM was mostly derived from exogenous pollution.Nitrogen speciation analysis showed that the organic nitrogen was the main form of the nitrogen in Panjiakou-Daheiting Reservoir and the bait and faces of fish were the important sources.Phosphorus speciation comparison showed that the phosphorus in the reservoirs mainly existed as the form of inorganic calcium-phosphorus?about 50%?,which indicated that the phosphorus was mainly from the primary minerals.The evaluation results of organic index and pollution index showed that the sediments of Panjiakou-Daheiting reservoirs were in the organic pollution status and have reached the level of serious pollution.In the reservoir,ammonia nitrogen diffuses from sediment to overlying water with flux between 1.64 and 33.05 mg·m-2·d-1,and the value of most of the points is relatively high.It is necessary to be alert to the effect of ammonia nitrogen release on water quality.Nitrate nitrogen and phosphate are mainly distributed from overlying water to sediment,the release flux ranged from-1.11 to 0.23 mg·m-2·d-1 and-0.45 to 0.18 mg·m-2·d-1,respectively.The potential release risk of nitrate nitrogen is very low,but phosphorus in sediment is high due to the high content of iron,aluminum,phosphorus and some organic phosphorus,and there is still a certain release risk under the condition of changing the environmental conditions of the interface between sediment and water. |
PDF Full Text Request