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.

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.