Nutrient leaching and copper speciation in compost-amended bioretention systems.

Area of Science:

• Environmental Engineering
• Water Quality Management
• Soil Science

Background:

• Bioretention systems are engineered to treat stormwater runoff.
• Compost amendments in bioretention systems can lead to nutrient and metal export.
• Dissolved organic matter (DOM) plays a role in contaminant transport.

Purpose of the Study:

• Quantify nutrient, copper, and DOM removal/export in compost-amended bioretention systems.
• Investigate the influence of DOM on copper leaching.
• Assess the speciation and potential toxicity of copper.

Main Methods:

• Simulated bioretention systems irrigated with stormwater.
• Leachate analysis for nitrates, phosphorus, copper, and DOM.
• Copper speciation modeling using Visual MINTEQ.

Main Results:

• Compost amendments resulted in significant nitrate, phosphorus, and DOM export.
• Bioretention systems initially exported copper but later became a sink.
• Dissolved copper was predominantly complexed with DOM.

Conclusions:

• Compost-amended bioretention systems can be sources of nutrients and DOM.
• DOM mobilizes copper from compost, influencing its leaching dynamics.
• Copper-DOM complexation may reduce copper's toxicity to aquatic life.