Increased phosphorus (P) availability under flooded, anaerobic conditions may accelerate P loss from soils to water bodies. Existing knowledge on P release to floodwater from flooded soils is limited to summer conditions and/or room temperatures. Spring snowmelt runoff, which occurs under cold temperatures with frequent freeze-thaw events, is the dominant mode of P loss from agricultural lands to water bodies in the Canadian Prairies. This research examined the effects of temperature on P dynamics under flooded conditions in a laboratory study using five agricultural soils from Manitoba, Canada. The treatments were (a) freezing for 1 wk at -20 °C, thawing and flooding at 4 ± 1 °C (frozen, cold); (b) flooding unfrozen soil at 4 ± 1 °C (unfrozen, cold); and (c) flooding unfrozen soil at 20 ± 2 °C (warm). Pore water and surface water were collected weekly over 8 wk and analyzed for dissolved reactive phosphorus (DRP), pH, calcium, magnesium, iron (Fe), and manganese (Mn). Soils under warm flooding showed enhanced P release with significantly higher DRP concentrations in pore and surface floodwater compared with cold flooding of frozen and unfrozen soils. The development of anaerobic conditions was slow under cold flooding with only a slight decrease in Eh, whereas under warm flooding Eh declined sharply, favoring reductive dissolution reactions releasing P, Fe, and Mn. Pore water and floodwater DRP concentrations were similar between frozen and unfrozen soil under cold flooding, suggesting that one freeze-thaw event prior to flooding had minimal effect on P release under simulated snowmelt conditions.

中文翻译：

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淹水厌氧条件下温度和冻结对土壤磷释放到上覆洪水的影响

在淹水、厌氧条件下增加磷 (P) 可用性可能会加速 P 从土壤到水体的流失。现有关于从淹水土壤释放到洪水中的磷的知识仅限于夏季条件和/或室温。春季融雪径流发生在寒冷的温度下，经常发生冻融事件，是加拿大大草原从农田到水体磷流失的主要模式。本研究使用加拿大马尼托巴省的五种农业土壤，在实验室研究中检验了温度对洪水条件下磷动态的影响。处理是（a）在-20°C下冷冻1周，在4±1°C下解冻和淹没（冷冻，冷）; (b) 在 4 ± 1 °C 下淹没未冻土（未冻、冷）；(c) 在 20 ± 2 °C（温暖）下淹没未冻土。在 8 周内每周收集孔隙水和地表水，并分析溶解的活性磷 (DRP)、pH、钙、镁、铁 (Fe) 和锰 (Mn)。与冻土和未冻土的冷驱相比，暖驱下的土壤显示出增强的磷释放，孔隙和地表洪水中的 DRP 浓度显着更高。在冷驱下厌氧条件的发展缓慢，Eh 仅略有下降，而在暖驱下，Eh 急剧下降，有利于释放 P、Fe 和 Mn 的还原溶解反应。冷驱下冻结和未冻结土壤的孔隙水和洪水 DRP 浓度相似，这表明在模拟融雪条件下，洪水前的一次冻融事件对 P 释放的影响最小。