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Tannin surges increase metal oxide loss and potentially destabilize soil aggregates

Zhifeng XieGuangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, ChinaGairen YangGuangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, China. Electronic address: [email protected]Yusong DengGuangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, ChinaYuhan HuangGuangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning 530004, ChinaHuili WangGuangxi Laboratory of Forestry, Guangxi Forestry Research Institute, Nanning 530002, ChinaJizhao CaoGuangxi Laboratory of Forestry, Guangxi Forestry Research Institute, Nanning 530002, China

Ecotoxicology and Environmental Safetyjournal2026en

ABI

Annotatsiya

The unclear mechanisms of interaction between plant-derived tannins and soil metal oxides (Al, Fe, Mn), especially in tannin-rich ecosystems like eucalyptus plantations, hinder accurate predictions of long-term soil health under continuous tannin exposure. Therefore, controlled soil column leaching experiments were conducted using different tannin types and concentrations. Metal oxide speciation (free, amorphous, and complexed) was quantified by a modified parallel extraction method, while aggregate stability was assessed through mean weight diameter (MWD) and geometric mean diameter (GMD) measurements. Results demonstrate that hydrolyzable tannins (e.g., gallic acid) exhibit superior metal mobilization capacity compared to condensed tannins (e.g., epigallocatechin gallate), establishing tannin chemistry as the primary determinant of oxides reactivity. A sequential dissolution-recomplexation pathway was identified, resulting in a 4 %-26 % decrease in amorphous oxides coupled with a 6 %-149 % increase in complexed oxides. The strong positive correlation between aggregate stability and complexed manganese content confirms its crucial cementing role. These findings resolve the apparent paradox of short-term stabilization versus long-term degradation in tannin-rich ecosystems by revealing that while initial complexation enhances aggregation, persistent tannin input ultimately depletes amorphous oxides, compromising soil structure. This mechanistic understanding provides a scientific basis for assessing metal-leaching risks and for developing sustainable management strategies in affected ecosystems. • Hydrolyzable tannins dominate Al/Fe oxide mobilization over condensed tannins. • A sequential dissolution-recomplexation pathway underlies tannin-driven metal cycling. • Tannin-rich soils shift from short-term stabilization to long-term degradation. • Sustainable management must balance soil carbon gains with metal leaching risks.

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Mavzular

Heavy metals in environment Chromium effects and bioremediation Arsenic contamination and mitigation

Identifikatorlar

DOI: 10.1016/j.ecoenv.2025.119601

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