Acidity controls on dissolved organic carbon mobility in organic soils
Acidity controls on dissolved organic carbon mobility in organic soils
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DOI：
10.1111/j.1365-2486.2012.02794.x
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发表时间：
2012-11-01
影响因子：
11.6
通讯作者：
Freeman, Chris
中科院分区：
文献类型：
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作者：
Evans, Chris D.;Jones, Tim G.;Freeman, Chris
欧洲和北美大部分地区地表水中的溶解有机碳 (DOC) 浓度有所增加，对陆地碳平衡、水生生态系统功能、水处理成本和人类健康产生影响。在过去的十年中，人们提出了许多假设来解释这一现象，从气候变化和土地管理到富营养化和酸沉降。由于依赖时间序列数据的相关分析以及缺乏对所提出的机制进行可靠的实验测试，这一争论的解决受到阻碍。在为期 4 年、涉及酸化和脱酸处理的四点重复田间实验中，我们检验了这样的假设：泥炭和有机矿物土壤中的高水平土壤酸度先前抑制了 DOC 淋溶，因此观察到的 DOC 增加是土壤酸度降低的结果。我们观察到所有地点的 DOC 和酸度变化之间存在一致的正相关关系。通过所有位点 DOC 和氢离子浓度标准化变化之间类似的双曲线关系来描述响应，表明潜在的普遍适用性。这些关系解释了附近监测溪流中观察到的 DOC 峰值浓度变化的很大一部分，并且应用于英国范围内的高地土壤 pH 数据集表明，自 1978 年以来，仅从酸化中恢复就可能导致土壤溶液 DOC 按栖息地类型增加 46126%。我们的研究结果提出了土壤酸度变化可能对生态系统碳平衡产生更广泛影响的可能性。硫沉积的减少可能会加速陆地碳流失，并使地表水恢复到自然的高 DOC 条件。
Dissolved organic carbon (DOC) concentrations in surface waters have increased across much of Europe and North America, with implications for the terrestrial carbon balance, aquatic ecosystem functioning, water treatment costs and human health. Over the past decade, many hypotheses have been put forward to explain this phenomenon, from changing climate and land management to eutrophication and acid deposition. Resolution of this debate has been hindered by a reliance on correlative analyses of time series data, and a lack of robust experimental testing of proposed mechanisms. In a 4 year, four-site replicated field experiment involving both acidifying and deacidifying treatments, we tested the hypothesis that DOC leaching was previously suppressed by high levels of soil acidity in peat and organo-mineral soils, and therefore that observed DOC increases a consequence of decreasing soil acidity. We observed a consistent, positive relationship between DOC and acidity change at all sites. Responses were described by similar hyperbolic relationships between standardized changes in DOC and hydrogen ion concentrations at all sites, suggesting potentially general applicability. These relationships explained a substantial proportion of observed changes in peak DOC concentrations in nearby monitoring streams, and application to a UK-wide upland soil pH dataset suggests that recovery from acidification alone could have led to soil solution DOC increases in the range 46126% by habitat type since 1978. Our findings raise the possibility that changing soil acidity may have wider impacts on ecosystem carbon balances. Decreasing sulphur deposition may be accelerating terrestrial carbon loss, and returning surface waters to a natural, high-DOC condition.