Tracking sources of groundwater nitrate contamination using nitrogen and oxygen stable isotopes at Beijing area,China     

Liu Mingzhu  Alfa-Sika Mande Seyf-Laye  Tchakala Ibrahim  Djaneye-Boundjou Gbandi  Chen Honghan 《Environmental Earth Sciences》2014,72(3):707-715

The identification of sources and behavior of contaminants is important to control and manage groundwater quality of aquifer systems in urban areas. In this study, hydrogeochemistry of major constituents and stable isotope ratios of nitrate in groundwater were determined to identify contamination sources and transformation processes occurring in soils and deeper groundwater of Beijing with intense human activities. The nitrogen and oxygen isotopic compositions of nitrate in pore water extracts from groundwater samples indicate at least three potential sources of nitrate in groundwaters at Beijing. Stable isotope analyses from this study site, which has atmospheric, chemical fertilizer and human waste nitrate sources, provide a tool to distinguish nitrate sources in a confined aquifer where concentrations alone do not. These data indicate that the most common sources of high nitrate concentrations in groundwater at Beijing are wastewater and denitrification process occurred specially in the Central area. NO₃–N and cation and anion concentrations (Ca²⁺, Mg²⁺ Cl^? and SO ₄ ² ) showed strong correlations indicating that they originated from the same sources. This study demonstrates that a thorough evaluation of hydrodynamic and hydrochemical parameters with dual isotopes of NO₃ ^? constitutes an effective approach for identifying sources and transformation processes of NO₃ ^? in deeper groundwater systems.  相似文献   

Hydrochemical and isotopic characterization of groundwater in the southeastern part of the Plateaux Region,Togo     

Kossitse Venyo Akpataku  Shive Prakash Rai  Masamaéya Dadja-Toyou Gnazou  Lallébila Tampo  Limam Moctar Bawa  Gbandi Djaneye-Boundjou 《水文科学杂志》2019,64(8):983-1000

Hydrochemical, inverse geochemical modelling and isotopic approaches are used to assess the hydrogeochemical evolution of groundwater from the basement aquifers in the southeastern part of the Plateaux Region, Togo. Groundwater originates from present-day rainwater infiltration and is mostly fresh and slightly acidic to neutral. Hydrochemical facies are predominantly mixed cations-HCO₃ associated with Ca/Mg-Cl, Na-HCO₃ and Na-Cl water types in equilibrium with kaolinite and Ca/Mg-smectites. They are related to silicates hydrolysis, anthropogenic contamination, nitrification/denitrification, mixing along flowpaths and dissolution/precipitation of secondary minerals. The pattern of flow paths is in accordance with an increasing trend in total dissolved solids (TDS) toward the potentiometric depression located in the central and southern parts of the aquifer system. Inverse geochemical modelling using the NETPATH-WIN model showed the relative importance of biotite, plagioclase and amphibole weathering and dissolution of secondary carbonate minerals along the flowpath, suggesting that an abundance of minerals is not necessarily the main factor controlling the groundwater chemistry evolution.  相似文献