Manganese oxidation and reduction in soils: effects of temperature, water potential, pH and their interactions

作者：Leigh A. Sparrow, N. C. Uren · 发表于：Soil Research · 年份：2014 · DOI：10.1071/sr13159 · 被引用次数：130 · 研究领域：Geochemistry and Elemental Analysis、Heavy metals in environment、Radioactive element chemistry and processing

Manganese (Mn) toxicity is a potential limitation to plant growth on acidic and poorly drained soils. Five laboratory experiments using such soils were conducted to examine the influence of soil temperature, pH and water potential on the redox reactions of Mn and the potential for Mn toxicity. The microbial inhibitor sodium azide was used in some experiments to assess the role of microorganisms in these reactions. The reduction of Mn oxides (MnOx) during waterlogging was faster at 20°C and 30°C than at 10°C or 4°C. Sodium azide slowed the reduction of Mn oxides at 20°C and 30°C during waterlogging but had little effect at 4°C and 10°C, suggesting that microbial MnOx reduction during waterlogging was minimal at the lower temperatures. Re-oxidation of Mn2+ in soil drained after severe waterlogging was only observed in soil not treated with sodium azide, indicating that even when very high concentrations of Mn2+ were present, Mn2+ oxidation was still microbial. Prior liming of aerobic soil established lower starting concentrations of water-soluble plus exchangeable (WS+E) Mn2+ and slowed the reduction of Mn oxides during subsequent waterlogging. After drainage, rapid re-oxidation of Mn2+ was observed in all lime treatments but was fastest at the two highest lime rates. In the fourth and fifth experiments, interactions between temperature and water potential were observed. When waterlogged soils were drained to –5 and –10 kPa, re-oxidation of Mn2+ occurred at both 10°C and 20°C. ...