Study on the mechanisms of water ecological remediation integrated by attapulgite and submerged macrophyte

<p>Phosphorus is considered to be a limiting nutrient that affects primary productivity, and sediment is an important source and sink of phosphorus in lakes. This study investigates how raw attapulgite (RAT) and thermally modified attapulgite (MAT) interact with submerged macrophyte <i>Hydrilla verticillata</i> to control sediment endogenous phosphorus. Attapulgite is rich in essential trace and major elements for plant growth, with properties such as non-toxicity, strong adsorption, and chemical stability. Results show that calcination at 500°C significantly enhances attapulgite's phosphorus adsorption capacity, increasing its specific surface area and pore volume. The growth of <i>Hydrilla verticillata</i> was improved by MAT, which enhanced its stress resistance through increased antioxidant enzyme activity. The addition of 10% and 20% RAT notably increased sediment redox potential, reduced sediment pH to neutral, and created favorable conditions for biological proliferation. Additionally, the findings indicate that the addition of attapulgite markedly reduces the organic matter and phosphorus content in sediments, helping to mitigate the risk of internal nutrient release in eutrophic lakes. In summary, attapulgite can accelerate the recovery of lake ecosystem by enhancing the stress resistance of submerged macrophyte, reducing the content of organic matter and phosphorus in sediments, improving the oxygen content of sediments, and reducing the release of endogenous phosphates. This study provides scientific evidence and theoretical support for the application of attapulgite in the restoration of eutrophic lake sediments.</p>