Preliminary study on strontium-rich characteristics of shallow groundwater in Dingtao Area,China

Based on the analysis of element correlation,the Gibbs diagram,hydro-geochemical ion ratios,isoline maps of groundwater and soil,and change patterns of strontium content after normalization,the study examines water-rock interaction of shallow groundwater in Dingtao area.The results suggest that strontium in the study area mainly comes from waterrock interactions,and the strata interacting with groundwater are the top of Quaternary and Neogene.The element correlation analysis shows that the formation of strontium-rich groundwater is sufficiently affected by sulfate and carbonate.The Gibbs diagram suggests that the chemical composition of groundwater is mainly influenced by water-rock interactions,accompanied by evaporation crystallization.c(Ca2++Mg2+)/c(HCO3-+SO42-)reflects that the main reactions in the groundwater system is weathering dissolution of carbonate and sulfate,and ion exchange takes place.c(Na+)/c(Cl-)indicates that Na+in groundwater may have waterrock interactions with rocks it flows through.c(Cl-)/c(Ca2+)indicates that the hydrodynamic condition in the pumping well is poor and the water circulation is slow.The study examines the macro isoline map change patterns,correlation curves of change of strontium content in groundwater and shallow soil,and correlation curves of change of strontium content in groundwater,shallow soil,and deep soil.The results suggest that the strontium content in the study area has the same change pattern in groundwater and in soil,which further indicates that strontium in the study area comes from water-rock interactions.

Qualitative analysis and quantitative simulation on Yin-Huang water salinization mechanism in Bei-Da-Gang Reservoir

Yellow River water transfer for Tianjin is important in solving the water shortage in Tianjin, which facilitate economic development and social progress for many years. Fresh water drawn from Yellow River（ i. e., Yin-Huang water） becomes saltier and saltier when being stored in the Bei-Da-Gang reservoir. We qualitatively analyze the water salinization mechanism based on mass transfer theory. The main factors are salinity transfer of saline soil, evaporation concentrating, and the agitation of wind. A simulative experimental pond and an evaporation pond were built beside the Bei-Da-Gang reservoir to quantitatively investigate the water salinization based on water and solute balance in the simulative pond. 80% of increased [Cl^-] is due to the salinity transfer of the saline soil and the other 20% is due to evaporation concentrating, so the former is the most important factor. We found that the salinization of Yin-Huang water can be described with a zero-dimension linear model.

Geochemical significance of the Paleogene soda-deposits bearing strata in Biyang Depression,Henan Province

The Biyang Depression, lying in the eastern Nanxiang Basin, has a dustpan-shape with faults developed to the southwest and southeast. The Paleogene Hetaoyuan Formation in this depression hosts one of the oldest soda-deposits, the Anpeng deposit. These sodium carbonate-bearing strata consist of lutites, muddy dolomites, and bedded soda-deposits, which are dominated by nahcolite with little trona, mirabilite, and halite. In the top Unit 3 and lower Unit 2 of Hetaoyuan Formation where the sodium carbonates are concentrated, dolomitic shale, muddy carbonate, and sodium carbonate can be separated based on their distinct A1203, TiO〉 Na20, MgO＋CaO, and LOI （loss on ignition） contents. By using Na20/（MgO＋CaO） ratio as an indicator for the relative concentration of Na carbonates to Mg-Ca carbonates, the muddy dolomites can be classified into two groups. One group with Na20/（MgO＋CaO）〈0.6 exhibits a positive correlation between this ratio and AI203＋TiO2 content, an proxy for ter- rigenous clastic input and the other group with Na20/（MgO＋CaO）〉0.6 presents a negative correlation. As the clastic propor- tion decreases, the former indicates that it tends to form pure Mg-Ca carbonates reflecting evaporation less than or equal to re- plenishment for the lake water in a relative humid climate, and the latter reveals a trend to form sodium carbonates with lake water＇s evaporation more than replenishment in a relatively dry climate. From muddy dolomite to sodium carbonate samples, with Na20/（MgO＋CaO） ratio increasing, the A1 normalized Zr, Ti, La, K, Rb, and Ba tend to be enriched and the post-Archean Average Shale （PAAS） normalized positive Eu anomaly becomes more obvious. Integrated with the high B contents and the report of searlesite in the bedded sodium carbonates and the regional extensional tectonic regime, the above geochemical characteristics were interpreted to signify hydrothermal contribution to forming these soda-deposits through the deep fault systems of basin margins.