Hydrogeochemical characterization in a possible carbon sink from shallow saline-alkaline groundwater in the eastern Hetao basin of Inner Mongolia in China

The question of how saline-alkaline groundwater can be used as a CO2 sink in arid saline-alkaline areas remains controversial. This study investigates the role of saline-alkaline groundwater as a CO2...

Processes Governing Alkaline Groundwater Chemistry within a Fractured Rock (Ophiolitic Mélange) Aquifer Underlying a Seasonally Inhabited Headwater Area in the Aladağlar Range (Adana, Turkey)

The aim of this study was to investigate natural and anthropogenic processes governing the chemical composition of alkaline groundwater within a fractured rock (ophiolitic mélange) aquifer underlying a seasonally inhabited headwater area in the Aladağlar Range (Adana, Turkey). In this aquifer, spatiotemporal patterns of groundwater flow and chemistry were investigated during dry (October 2011) and wet (May 2012) seasons utilizing 25 shallow hand-dug wells. In addition, representative samples of snow, rock, and soil were collected and analyzed to constrain the PHREEQC inverse geochemical models used for simulating water-rock interaction (WRI) processes. Hydrochemistry of the aquifer shows a strong interseasonal variability where Mg–HCO3 and Mg–Ca–HCO3 water types are prevalent, reflecting the influence of ophiolitic and carbonate rocks on local groundwater chemistry. R-mode factor analysis of hydrochemical data hints at geochemical processes taking place in the groundwater system, that is, WRI involving Ca- and Si-bearing phases; WRI involving amorphous oxyhydroxides and clay minerals; WRI involving Mg-bearing phases; and atmospheric/anthropogenic inputs. Results from the PHREEQC modeling suggested that hydrogeochemical evolution is governed by weathering of primary minerals (calcite, chrysotile, forsterite, and chromite), precipitation of secondary minerals (dolomite, quartz, clinochlore, and Fe/Cr oxides), atmospheric/anthropogenic inputs (halite), and seasonal dilution from recharge.

Nondestructive Microscopy Test on Damage of Waterproof Material in Underground Engineering

The microstructure changes of acrylate spray-on waterproof material in alkaline groundwater environment were tentatively studied with X-ray microscopy (XRM), and the validity of deciding the failure of the material was explored in paper. Regarded NaOH solution with pH=12 as corrosive medium, after the immersion in the alkaline solution, spray-on waterproof material was scanned with XRM, and the structure was characterized with some indexes such as porosity and pore connectivity. The results show that when the waterproof material is immersed in alkaline solution for some time, the surface of the material becomes uneven, the overall porosity falls and the pore connectivity rises. It is feasible to study on the failure of waterproof material in underground engineering with XRM.