Quantifying chemical reactions by using mixing analysis.

Area of Science:

• Hydrogeology
• Environmental Chemistry
• Geochemistry

Background:

• Urban aquifers face complex chemical processes impacting groundwater quality.
• Organic pollutants pose risks to water resources in populated areas.
• Understanding these processes is crucial for effective water management.

Purpose of the Study:

• To develop and apply a methodology for quantifying chemical processes in urban aquifers.
• To determine mixing ratios and identify specific geochemical reactions affecting groundwater.
• To assess the impact of recharge sources on groundwater chemistry.

Main Methods:

• Utilized mixing calculations to quantify chemical processes affecting organic pollutants.
• Identified recharge sources (end-members) and selected relevant chemical species.
• Analyzed groundwater samples from the Besòs River Delta over multiple field campaigns.
• Incorporated calcite and magnesite dissolution, aerobic respiration, and denitrification into the analysis.

Main Results:

• Successfully applied the methodology to the Besòs River Delta aquifer.
• Required three distinct river end-members (W1, D1, D2) to capture temporal variability.
• Quantified mixing ratios and identified key chemical processes at observation points.
• Demonstrated the utility of the approach for understanding groundwater evolution.

Conclusions:

• The proposed mixing calculation approach is effective for quantifying chemical processes in urban aquifers.
• The methodology provides insights into groundwater-surface water interactions and geochemical transformations.
• This approach aids in managing groundwater resources impacted by pollution and recharge dynamics.