A conceptual model for correcting groundwater 14C age

Determining groundwater age is critical for understanding hydrogeological systems and groundwater renewability. The C-14 with a half time of 5730 years is an important tracer to determine groundwater age ranging typically from 1000 years to 40,000 years. The use of C-14 age relies on the dissolved inorganic carbon of groundwater. The correction of the C-14 age of groundwater remains largely uncertain due to complex sources of dissolved inorganic carbon. This study provides a novel conceptual model to correct groundwater C-14 age by determining a virtual initial C-14 content (A(0)). This method has avoided large uncertainties of parameters used in conventional methods, such as the delta C-13 values of soil CO2 and (continental) carbonates. The uncertainty of the method is relatively small. A case study from the Xifeng loess tableland in the NW China showed that the initial C-14 content was estimated to be 46.1 +/- 1 percent Modern Carbon through determining the groundwater age around the water table using soil water percolation velocity, resulting in the uncertainty within 200 years, smaller than 500-2000 years using conventional methods. This study would help determine groundwater age and understand hydrogeological conditions.

Automated summary

Determining groundwater age is crucial for understanding hydrogeological systems and groundwater renewability. This study introduces a novel conceptual model for correcting groundwater C-14 age by determining a virtual initial C-14 content. This method avoids uncertainties associated with conventional approaches and has relatively smaller uncertainty.