Are sustainable drainage systems (SuDS) effective at retaining dissolved trace elements?

Area of Science:

• Environmental Science
• Water Quality Management
• Urban Hydrology

Background:

• Urban and road runoff increase trace element contamination.
• Sustainable drainage systems (SuDS) are vital for mitigating these contaminants.
• Limited research exists on SuDS' dissolved trace element removal capabilities.

Purpose of the Study:

• To assess the trace element removal efficiency of different SuDS types.
• To investigate dissolved phase trace element removal in SuDS.
• To understand the impact of rainfall events and antecedent conditions on SuDS performance.

Main Methods:

• Water samples collected from three diverse SuDS in Devon over six rainfall events.
• Analysis of 15 trace elements, including during the first flush of runoff.
• Comparison of removal rates across different SuDS types and rainfall intensities.

Main Results:

• SuDS showed variable, generally modest, removal of dissolved trace elements.
• Highest element concentrations occurred during the first flush, influenced by antecedent dry periods.
• During high flows, SuDS could release trace elements from resuspended fine particulates.
• Mature ponds with macrophytes retained solids and metals, but poor maintenance reduced efficiency.

Conclusions:

• SuDS performance in trace element removal is inconsistent and element-specific.
• Effective long-term management planning is essential for optimizing SuDS contaminant removal.
• Understanding first flush dynamics and potential for resuspension is critical for SuDS design and maintenance.