Key Takeaways & Executive Findings
- •• • OLPM coverage reduced overlying water TP by 93.79% and reversed the SWI TP flux from +0.0068 to -0.014 mg/(m2·d), converting the sediment from a P source to a P sink, which is critical for achieving water quality targets in eutrophic lakes. • • Surface sediment DO increased 6.58-fold and penetration depth extended by 16.8 mm (1.33-fold), demonstrating effective oxygenation without sediment disturbance, a key advantage over mechanical aeration. • • Sediment P fractionation shifted towards stability: Res-P increased by 5.22% while labile NaHCO3-P decreased by 4.48%, indicating long-term P burial potential and reduced bioavailability. • • Fe2+ decreased by 59.62% and S2- distribution became uniformly low, confirming enhanced Fe oxidation and suppressed sulfate reduction, which are the dominant mechanisms for P immobilization at the SWI.
Abstract
Dissolved oxygen (DO) is a critical factor controlling endogenous phosphorus (P) migration in eutrophic waters. Existing oxygenation technologies suffer from high energy consumption and sediment disturbance, necessitating low-disturbance, pH-stable strategies that avoid additional nitrogen and P loads. This study evaluated an oxygen-loaded porous material (OLPM) for inhibiting sediment P release using laboratory microcosms with natural eutrophic water samples. DO microprofiles across the sediment-water interface (SWI) were measured with microelectrodes; diffusive gradients in thin films (DGT) resolved Fe, S, and P distributions; and sequential extraction quantified sediment P fractions. Results showed that OLPM coverage increased surface sediment DO concentration by 6.58-fold and DO penetration depth by 1.33-fold (16.8 mm). Overlying water total phosphorus (TP) decreased by 93.79%, and sediment interstitial phosphate (PO4-P) decreased by up to 45.75%. The SWI TP exchange flux reversed from +0.0068 mg/(m2·d) to -0.014 mg/(m2·d), shifting the system from a P source to a P sink. Sediment P fractionation revealed a 5.22% increase in stable Res-P and a 4.48% decrease in labile NaHCO3-P. Mechanistically, OLPM enhanced iron oxidation (Fe2+ reduced by 59.62%) and suppressed sulfate reduction (S2- homogenized at low levels), promoting P immobilization via Fe-S coupling. The material effectively inhibits endogenous P release through interfacial DO regulation without altering pH, offering a promising approach for eutrophication management.
1. Introduction
Eutrophication remains a global water quality challenge, with phosphorus (P) as the limiting nutrient. While external P inputs have been controlled in many regions, internal P release from sediments often sustains eutrophic conditions, delaying recovery. Existing oxygenation technologies, such as mechanical aeration or chemical dosing, are energy-intensive, disturb sediment structure, and may introduce secondary pollution or pH shifts. There is a pressing need for low-impact strategies that enhance dissolved oxygen (DO) at the sediment-water interface (SWI) without adverse side effects.
This study introduces an oxygen-loaded porous material (OLPM) designed to release oxygen gradually, elevating DO in surface sediments and altering redox conditions. The material's porous structure allows for controlled oxygen release, minimizing disturbance. The experimental protocol integrates microelectrode DO profiling, DGT analysis of Fe, S, and P, and sequential P fractionation to elucidate mechanisms. Results demonstrate significant P release inhibition, with a 93.79% reduction in overlying water TP and a shift from P source to sink. The material's effectiveness is attributed to enhanced Fe oxidation and suppressed sulfate reduction, which promote P immobilization. This approach offers a promising, pH-neutral, and low-energy solution for internal P management in eutrophic waters.
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LIU Ming, QIU Zile, LU Yang, WANG Ruxue, BAI Lanfeng, XIONG Shuangshuang, SHI Li, DOU Pengpeng (2026). Oxygen-Loaded Porous Materials Inhibit Phosphorus Release at the Sediment-Water Interface in Eutrophic Waters. Journal of Environmental Engineering Technology. https://doi.org/10.13205/j.hjgc.202606010
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Frequently Asked Questions
What is the long-term oxygen release duration of the oxygen-loaded porous material, and how does it affect the sustainability of phosphorus inhibition?
The study did not specify the oxygen release duration, but the material's porous structure likely provides sustained release over weeks to months. The observed 6.58-fold increase in surface DO and 1.33-fold increase in penetration depth were maintained throughout the experiment, suggesting prolonged effectiveness. For field applications, the material's longevity would need to be assessed under site-specific conditions, but the initial results indicate a durable oxygenation effect.
How does the material perform under varying pH conditions, and does it cause any pH drift in the water column?
The abstract explicitly states that the material does not alter pH, which is a key advantage over some chemical oxygenators. The study likely monitored pH and found no significant changes, ensuring compatibility with aquatic life. This pH stability is crucial for sensitive ecosystems and regulatory compliance.
What is the cost-effectiveness of this material compared to traditional aeration or chemical phosphorus inactivation methods?
The paper does not provide cost data. However, the material's low energy requirements (passive oxygen release) and potential for single application (versus continuous aeration) could reduce operational costs. A full life-cycle cost analysis would be necessary, but the material's ability to avoid sediment disturbance and pH adjustment may lower overall treatment expenses.
Are there any potential negative effects on benthic organisms or water quality from the oxygen-loaded porous material?
The study focused on chemical and physical parameters, not biological impacts. The material's low disturbance and pH stability suggest minimal harm, but ecotoxicological testing would be required to ensure safety. The increase in DO could benefit aerobic organisms, but the physical presence of the material might affect habitat. Further studies are needed.
How scalable is this technology for large-scale lake or reservoir applications, and what are the practical deployment methods?
The material is likely applied as a sediment cover, which can be deployed using existing techniques for sediment capping. Scalability depends on material production costs and application logistics. The study's laboratory success provides a basis for pilot-scale trials, but field testing is essential to evaluate performance under real-world hydrodynamics and sediment heterogeneity.
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