A simple methodology for the evaluation of groundwater pollution risks

Area of Science:

• Environmental Science
• Hydrogeology
• Soil Science

Background:

• Groundwater is a critical resource for drinking and irrigation, necessitating the preservation of its quality and availability.
• Assessing pollutant export to groundwater is vital for effective environmental management and protection strategies.

Purpose of the Study:

• To evaluate the potential export of soil contaminants to groundwater via soil drainage.
• To quantify the contribution of pollutants, particularly zinc, to groundwater following a toxic spill event.

Main Methods:

• Measuring soil solution contaminants at the soil base after simulated rainfall.
• Estimating drainage water using a daily water balance "bucket model" with stochastic climate data (50-100 years).
• Applying the methodology in the Guadiamar valley post-Aznalcóllar pyrite mine spill.

Main Results:

• Zinc (Zn) was identified as the dominant contaminant, contributing 1.2 g m(-2)year(-1) to groundwater.
• A gravel-rich horizon below 50 cm depth was found to increase drainage rates.
• These findings indicate a significant threat to groundwater quality in the studied area.

Conclusions:

• The developed methodology effectively assesses pollutant export to groundwater.
• Zinc contamination poses a substantial risk to groundwater resources in the Guadiamar valley.
• Subsurface geological conditions, like gravelly horizons, can exacerbate groundwater contamination risks.