School of Biological Sciences, The University of Adelaide, Adelaide, Australia.
School of Physical Sciences, Department of Earth Sciences, Metal Isotope Group (MIG), The University of Adelaide, Adelaide, Australia.
Chemosphere. 2022 Jul;299:134383. doi: 10.1016/j.chemosphere.2022.134383. Epub 2022 Mar 23.
Climate change is leading to global sea level rise. Storm surges and higher tides will generate short-term 'pulses' of seawater into freshwater systems, often for the first time in over 3000 years. The effect of increased seawater inundation upon soil geochemistry is poorly understood. We identified 12 sites in South Australia which are predicted to be inundated by seawater storm surges in the next 20 years. Within these 12 sites are three distinct environments; fresh water streams and lakes, hypersaline saltmarsh and mangroves, and acid sulfate soils. Soils were inundated with seawater under laboratory conditions to replicate a short-term (two weeks) inundation by a storm surge. Lowering of redox potential and dissolution of high concentrations of reactive Mn and Fe in freshwater environments lead to the release of dissolved Fe and Mn in the soils from freshwater environments. Soils also released As, Cu, Ni, Cd and Co, while Zn and Pb were less mobilised. Concentrations of metals released exceeded water quality guidelines to protect freshwater aquatic ecosystems in most cases. By comparison, hypersaline soils only released minor amounts of Mn, Fe, Cd and Ni, and only in some of the soils. The moderately acidic acid sulfate soil (pH 5.41) reductively dissolved Mn and Fe releasing significant amount of Fe and Mn as well as As, Cu, Ni, Cd and Co, whereas almost all metal species decreased in the porewaters of the strongly acidic acid sulfate soil (pH 2.77). The response to short-term seawater inundation in acid sulfate soils was dependent upon the baseline soil acidification status. This study highlights the need for further research on seawater inundation of coastal soils as sea levels rise and storm surges penetrate further inland.
气候变化导致全球海平面上升。风暴潮和高潮位将在短时间内（通常是 3000 多年来的首次）将海水“脉冲式”涌入淡水系统。海水入侵对土壤地球化学的影响尚未得到充分了解。我们在南澳大利亚确定了 12 个预计在未来 20 年内将被海水风暴潮淹没的地点。在这 12 个地点中，有三种不同的环境：淡水溪流和湖泊、高盐沼泽和红树林以及酸性硫酸盐土壤。在实验室条件下，用海水淹没土壤，模拟风暴潮的短期（两周）淹没。在淡水环境中，氧化还原电位降低和高浓度反应性 Mn 和 Fe 的溶解导致淡水环境中的土壤中溶解的 Fe 和 Mn 释放。土壤还释放了 As、Cu、Ni、Cd 和 Co，而 Zn 和 Pb 的迁移性较小。在大多数情况下，释放的金属浓度超过了保护淡水水生生态系统的水质指南。相比之下，高盐土壤仅释放少量的 Mn、Fe、Cd 和 Ni，而且仅在部分土壤中释放。中等酸性的酸性硫酸盐土壤（pH 值为 5.41）将 Mn 和 Fe 还原溶解，释放出大量的 Fe 和 Mn 以及 As、Cu、Ni、Cd 和 Co，而在 pH 值为 2.77 的强酸性酸性硫酸盐土壤的孔隙水中，几乎所有金属物种都减少了。酸性硫酸盐土壤对短期海水淹没的反应取决于基线土壤酸化状况。本研究强调了随着海平面上升和风暴潮进一步深入内陆，需要进一步研究沿海土壤的海水淹没情况。
