RELATIONSHIP BETWEEN DEVELOPMENTS OF THE HUANGHE AND YONGDING RIVERS AND THE EVOLUTION OF THE FOSSIL LAKES OF THE CENOZOIC ERA IN THE DRAINAGE AREA

The Huanghe and Yongding rivers were formed before the early and middle Pliocene epoch. Then they became interior rivers because of the appearance of interior fault lake basins at the end of the Pliocene epoch. The interior flow period continued until the end of the early Pleistocene or the middle pf the Middle Pleistocene, and then they changed into the exterior rivers again till today.

Eutrophication Evaluation of Water Body at Huailai Section of the Yongding River

In order to understand the water pollution characteristics in Huailai section of the Yongding River,the monitoring from November of 2016 to October of 2017 was conducted. 6 sampling points were selected for monitoring 6 indicators,and the temporal-spatial variation characteristics of nitrogen and phosphorus in the river were explored. Moreover,the ratio of nitrogen to phosphorus and an exponential universal formula of power function in logarithmic form were used to analyze temporal-spatial variation rules of nitrogen and phosphorus in water,assess the degree of eutrophication,and analyze eutrophication risk. The results showed that water pollution in Huailai section of the Yongding River was more serious. TN was13. 25 times of concentration limit of class III water in the dividing of surface water environment function area in the " 13 thFive-year" Development Planning" of National Environmental Protection Standard. ON and NO-3-N were the main forms of TN,while mean value of TP was 0. 64 mg/L,and each index had the characteristics of agricultural non-point source pollution. The temporal-spatial distribution characteristics of nitrogen and phosphorus in the water body was obvious. At the time scale,the concentrations of nitrogen and phosphorus in the water body showed seasonal variation; at the space scale,the distribution of nitrogen and phosphorus in the water body was similar. The annual average ratio of nitrogen and phosphorus in Huailai section of the Yongding River was 32. 78,and the phytoplankton was in the overall state of phosphorus limitation. During the flat water period,phosphorus was the limiting nutrient element,and the ratio of nitrogen and phosphorus in the dry period and the abundant water period was suitable for the growth and reproduction of algae. The temporal-spatial variation of water body in Huailai section of the Yongding River was mostly in the " eutrophication" stage. The maximum EI value was 228. 11 in dry season,and the lowest was 213. 06 in flood season,while it was218. 30 in flat water period. The fluvial dynamics process in Huailai section of the Yongding River was good,and the flow pattern of the river was continuous. The flow velocity of the main stream was 0. 43-1. 45 m/s,which was much larger than that of the algal bloom. The risk of cyanobacteria blooms in the main stream was low.

A HYDROECOLOGICAL STUDY OF EUTROPHIC YONGDING RESERVOIR

The water quality of Yongding Reservoir was evaluated by using aquatic ecological techniques combinedwith chemical and physical methods.Of the 14 biological,chemical and physical parameters examined inthis study,10,including primary productivity and chlorophyll a.were found to exceed the critical levelsfor eutrophic waters.Most of the indicators and Carlson’s Comprehensive Trophic State Index(TST)indi-ces indicated that the water quality of the western side of the reservoir was worse than that of the easternside.Polluted water from the Yongding River was considered a main source of pollutants in the reser-voir,while the farming of carp in net cages also contributed to the low water quality.A comparison ofthe water quality data in 1982 and 1988 indicated that the rate of eutrophication of Yongding Reservoir was alarming.

Typical earthquake-induced soft-sediment deformation structures in the Mesoproterozoic Wumishan Formation, Yongding River Valley, Beijing, China and interpreted earthquake frequency

The Mesoproterozoic Wumishan Formation, composed of dolomite is a widely distributed stratigraphic unit in the Beijing area. It was formed over a long period of time in the Yan-Liao aulacogen, a stable peritidal environment that was ideal for recording earthquakes in the form of soft-sediment deformation structures (SSDS). Numerous examples occur in the upper part of the Wumishan Formation, along the Yongding River Valley. In addition, brittle structures include intrastratal fault and seismically cracked breccias. The soft-sediment deformation structures include liquefied features (diapirs, clastic dykes, convolute bedding), compressional deformation features (accordion folds, plate-spine breccias, mound-and-sag structures), and extensional plastic features (loop-bedding). Based on the regional geological setting and previous research, movements along the main axial fault of the Yan-Liao aulacogen are considered as the triggers for earthquakes since the Early Mesoproterozoic. The number and distribution of the SSDS suggest the major earthquake frequency in the Wumishan Formation of 20 to 32 thousand years.

Water quality characteristics and assessment of Yongding New River by improved comprehensive water quality identification index based on game theory

The Yongding New River is essential for the water supplies of Tianjin.To date,there is no comprehensive report that assesses the year-round water quality of the Yongding New River Main stream.Moreover,little attention has been given to determining a combined weight for improving the traditional comprehensive water quality identification index(ICWQII)by the game theory.Seven water quality parameters were investigated monthly along the main stream of the Yongding New River from May 2018 to April 2019.Organic contaminants and nitrogen pollution were mainly caused by point sources pollution,and the total phosphorus mainly by non-point source pollution.Dramatic spatio-temporal variations of water quality parameters were jointly caused by different pollutant sources and hydrometeorological factors.In terms of this study,an improved comprehensive water quality identification index(ICWQII)based on entropy weight or variation coefficient and traditional CWQII underestimated the water qualities,and an ICWQII based on the superstandard multiple method overvalued the assessments.By contrast,water qualities assessments done with an ICWQII based on the game theory matched perfectly with the practical situation.The ICWQII based on game theory proposed in this study takes into account not only the degree of disorder and variation of water quality data,but also the influence of standard-exceeded pollution indicators,whose results are relatively reasonable.All findings and the ICWQII based on game theory can provide scientific support for decisions related to the water environment management of the Yongding New River and other waters.

Development of a groundwater flow and reactive solute transport model in the Yongding River alluvial fan,China

The Yongding River in the western suburbs of Beijing has been recharged with reclaimed water since 2010 for the purpose of ecological restoration.Where the reclaimed water is not well treated,it poses a danger to the aquifer underneath the river.To provide a reliable tool which could be used in future research to quantify the influence of reclaimed water in the Yongding River on the local groundwater environment,a transient groundwater flow and reactive solute transport model was developed using FEFLOW^TM in the middle-upper part of the Yongding River Alluvium Fan.The numerical model was calibrated against the observed groundwater levels and the concentrations of typical solutes from June 2009 to May 2010 and validated from June 2010 to December 2010.The average RMSE and R2 of groundwater level at four observation wells are 0.48 m and 0.61,respectively.The reasonable agreement between observed and simulated results demonstrates that the developed model is reliable and capable of predicting the behavior of groundwater flow and typical contaminant transport with reactions.Water budget analysis indicates that the water storage in this aquifer had decreased by 43.76×10^6m^3 distributions of typical solutes suggest that the middle and southern parts of the unconfined aquifer have been polluted by previous discharge of industrial and domestic sewage.The results underscore the necessity of predicting the groundwater response to reclaimed water being discharged into the Yongding River.The study established a coupled groundwater flow and reactive solute transport model in the middle-upper part of the Yongding River Alluvium Fan,one of the drinking water supply sites in Beijing city.The model would be used for risk assessment when reclaimed water was recharged into Yongding River.

永定河上游地表水氟污染分布特征与健康风险评价

The excessive exposure to high concentrations of fluoride in drinking water can lead to a serious disease called fluorosis.The upstream region of the Yongding River is an ecological protection area for Beijing.Some studies have reported that there is a high concentration of fluoride in the groundwater in this area.However,there are few data on the distribution of fluoride in surface water and health risk assessments in this area.In this study,the fluoride concentrations were determined by using the spectrophotometric method using data from 2013 to 2017 from 9 surface water quality monitoring stations in the upper reaches of the Yongding River.The health risks of fluoride were assessed using the approach developed by the United States Environmental Protection Agency(US EPA).The results indicated that the fluoride content in the drinking water ranged from 0.30 to 1.50 mg L 1,with an average of 0.86 mg L"1.In total,22.7%of the analyzed samples exceeded the Chinese limit of 1.0 mg L"1 for fluoride,and 5.5%of samples had less than the permissible limit of 0.5 mg L"1.Higher fluoride concentrations and fluorosis hotspots were found to be predominately located downstream of the Yanghe River close to the Guanting Reservoir,where 71.4%of samples exceeded the limit of 1.0 mg/L'1.The spatial distribution of high fluoride concentrations was found to be primarily determined by industry.The hazard quotient(HQ)index for children,teenagers and adults indicated that 19.6%,15.6%,and 5.1%of the samples in the upper reaches of the Yongding River,respectively,posed health hazards to the associated groups.Furthermore,the HQ index more than 1 for children,teenagers and adults had values of 64.3%,56.1%,and 19.4%,respectively,in samples from the downstream region of the Yanghe River.Therefore,there are potential risks of dental and skeletal fluorosis in the upper river reaches of the Yongding River.It is imperative to take measures to reduce the fluoride pollution in surface water and control fluorosis.Action should be taken to improve the disposal of industrial waste.