Impact of cascade damming on nitrogen and phosphorus nutrient distribution in the Heihe River Basin
Cascade dams alter the hydrological characteristics along with material transport and transformation patterns of rivers,thereby influencing water environment quality.Therefore,exploring the spatio-temporal distri-bution impact of nitrogen(N)and phosphorus(P)nutrients in the upper reaches of Heihe River under cascade dams and analyzing eutrophication risks is of certain reference significance for ecological restoration and cascade water resources management in Heihe River Basin.This study conducted statistical analysis on multi-year data of 10 water physicochemical indicators at 16 major monitoring sections in the upper reaches of Heihe River.The re-sults demonstrate that there were significant spatio-temporal differences in the physicochemical properties of the water in the upper reaches of Heihe River.The overall water quality is weakly alkaline with good self-purification capacity,and the concentrations of total nitrogen(TN)and total phosphorus(TP)comply with Class Ⅲ and Class Ⅱ water quality standards.For temporal distribution,the concentrations of TN,ammonia nitrogen(NH3-N),and nitrite nitrogen(NO2-N)in the upper reaches of Heihe River are higher during the dry season than the flood season,while TP concentration is higher during the flood season than the dry season.In terms of spatial dis-tribution,the distribution of nutrient salts in individual reservoirs exhibits potential cumulative effects,but under the action of cascade reservoirs,the overall distribution of nutrient salts shows a decreasing trend,indicating that the cumulative effect along the river is gradually weakening.Furthermore,NH3-N and NO2-N are primarily dis-tributed in the middle layer of the reservoir,while TN and TP have higher concentrations in the lower layer than the upper layer,indicating a stratification phenomenon with a large amount of N and P accumulating in the lower layer sediment.This study highlights the necessity for the implementation of management strategies aimed at mit-igating eutrophication risks.
cascade dammingnitrogen and phosphorus nutrientsspatio-temporal distributioneutrophication assessmentHeihe River
万方数据
维普
