Effect of groundwater on the ecological water environment of typical inland lakes in the Inner Mongolian Plateau

To explore the causes of the ecological environment deterioration of lakes in the Inner Mongolia Plateau,this study took a typical inland lake Daihai as an example,and investigated the groundwater recharge in the process of lake shrinkage and eutrophication.Using the radon isotope(^(222)Rn)as the main means of investigation,the ^(222)Rn mass balance equation was established to evaluate the groundwater recharge in Daihai.The spatial variability of ^(222)Rn activity in lake water and groundwater,the contribution of groundwater recharge to lake water balance and its effect on nitrogen and phosphorus pollution in lake water were discussed.The analysis showed that,mainly controlled by the fault structure,the activity of ^(222)Rn in groundwater north and south of Daihai is higher than that in the east and west,and the difference in lithology and hydraulic gradient may also be the influencing factors of this phenomenon.The ^(222)Rn activity of the middle and southeast of the underlying lake is greater,indicating that the ^(222)Rn flux of groundwater inflow is higher,and the runoff intensity is greater,which is the main groundwater recharge area for the lake.The estimated groundwater recharge in 2021 was 3017×10^(4) m^(3),which was 57%of the total recharge to the lake,or 1.6 times and 8.1 times that of precipitation and surface runoff.The TN and TP contents in Daihai have been rising continuously,and the average TN and TP concentrations in the lake water in 2021 were 4.21 mg·L^(−1) and 0.12 mg·L^(−1),respectively.The TN and TP contents entering the lake with groundwater recharge were 6.8 times and 8.7 times above those of runoff,accounting for 87%and 90%of the total input,respectively.The calculation results showed that groundwater is not only the main source of recharge for Daihai,but also the main source of exogenous nutrients.In recent years,the pressurized exploitation of groundwater in the basin is beneficial in increasing the groundwater recharge to the lake,reducing the water balance difference of the lake,and slowing down the shrinking degree of the lake surface.However,under the action of high evaporation,nitrogen and phosphorus brought by groundwater recharge would become more concentrated in the lake,leading to a continuous increase in the content of nutrients and degree of eutrophication.Therefore,the impact of changes in regional groundwater quantity and quality on Daihai is an important issue that needs further assessment.

Determining the groundwater basin and surface watershed boundary of Dalinuoer Lake in the middle of Inner Mongolian Plateau,China and its impacts on the ecological environment

The surface watershed and groundwater basin have fixed recharge scale,which are not only the basic unit for hydrologic cycle research but also control the water resources formation and evolution and its corresponding eco-geological environment pattern.To accurately identify the boundary of the surface watershed and groundwater basin is the basis for properly understanding hydrologic cycle and conducting the water balance analysis at watershed scale in complicated geologic structure area,especially when the boundary are inconsistent.In this study,the Dalinuoer Lake located in the middle of the Inner Mongolian Plateau which has complicated geologic structure was selected as the representative case.Based on the multidisciplinary comprehensive analysis of topography,tectonics,hydrogeology,groundwater dynamics and stable isotopes,the results suggest the following:(1)The surface watershed ridge and groundwater basin divide of Dalinuoer Lake are inconsistent.The surface watershed was divided into two separate groundwater systems almost having no groundwater exchange by the SW-NE Haoluku Anticlinorium Fault which has obvious water-blocking effect.The surface drainage area of Dalinuoer Lake is 6139 km^(2).The northern regional A is the Dalinuoer Lake groundwater system with an area of 4838 km^(2),and the southern regional B is the Xilamulun Riverhead groundwater system with an area of 1301 km^(2).(2)The groundwater in the southern of regional A and the spring-feeding river are the important recharge sources for the Dalinuoer Lake,and it has greater recharge effects than the northern Gonggeer River system.(3)It is speculated that the trend of Haoluku Anticlinorium Fault is the boundary of the westerlies and the East Asian summer Monsoon(EASM)climate systems,which further pinpoints the predecessor’s understanding of this boundary line.At present,the Dalinuoer Lake watershed is proved to have gone through a prominent warming-drying trend periods,which leads to the precipitation reduction,temperature rise,human activities water usage increasement.So the hydrological cycle and lake eco-environment at watershed scale will still bound to be change,which may pose the potential deterioration risk on the suitability of fish habitat.The results can provide basic support for better understanding water balance evolution and lake area shrinkage cause as well as the ecological protection and restoration implementation of Dalinuoer Lake watershed.

Application value of 3D printing assisted pedicle screw placement in the treatment of thoracolumbar spinal fractures

Objective:To evaluate the value of 3D printing assisted pedicle screw placement in the treatment of thoracolumbar spinal fractures.Methods: 56 cases of thoracolumbar spinal fractures patients underwent 3D printing assisted pedicle screw placement (study group) and another 56 cases of thoracolumbar spinal fractures patients underwent conventional screw placement (control group) in our department from February 2016 to September 2017 were selected. Then the surgical related indicators, JOA score, the reduction of injured vertebrae and complications were recorded and compared between groups at different time points, including, before operation (T0), postoperative 1mon (T1), postoperative 6mon (T2) and postoperative 12mon (T3).Results: The operation time, intraoperative X-ray fluoroscopy frequency and intraoperative blood loss in the study group were significantly lower than those in the control group (P<0.05), meanwhile the accuracy rate of screw placement was significantly higher than that of the control group (P<0.05). JOA scores at T1, T2 and T3 in both groups were significantly higher than those at T0 (P<0.05), and JOA scores at all postoperative time points in the study group were significantly higher than those in the control group (P<0.05). Compared with T0, the ratio of the anterior and posterior border height of injured vertebrae in the two groups at T2 was significantly increased (P<0.05), while the Cobb Angle of sagittal kyphoid significantly was decreased (P<0.05). Meanwhile, the reduction of injured vertebrae in the study group was significantly better than that the control group at T2 (P<0.05). The incidence of complications in the study group was significantly lower than that in the control group (P<0.05).Conclusion: The application of 3D printing assisted pedicle screw placement in the treatment has the advantages of less injury to patients, good prognosis and high safety, which is worthy of clinical application.