Alternative explanations for rising dissolved organic carbon export from organic soils
Alternative explanations for rising dissolved organic carbon export from organic soils
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DOI：
10.1111/j.1365-2486.2006.01241.x
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发表时间：
2006-11-01
影响因子：
11.6
通讯作者：
Cresser, Malcolm S.
中科院分区：
文献类型：
--
作者：
Evans, Christopher D.;Chapman, Pippa J.;Cresser, Malcolm S.
自1988年以来，在酸性水域监测网络（AWMN）中，英国湖泊和溪流的溶解有机碳（DOC）浓度平均增加了91%。在欧洲和北美大部分地区的地表水中也观察到类似的DOC增加。与其他与碳循环有关的研究一样，关于DOC上升原因的争论主要集中在与气候变化有关的因素上。我们的泥炭岩心实验数据支持气候对DOC的影响，特别是在好氧条件下，以及在较小程度上的厌氧条件下，产量随温度的升高而增加。然而，我们认为气候因素可能不是DOC变化的主要驱动因素。土壤水的高酸度和离子强度抑制了DOC的溶解度，自1980年代以来，由于硫沉积的减少，这两者都有所下降，1990年代在联合王国由于海盐沉积的周期性下降而有所增加。我们的观测和实验数据表明，土壤溶液中DOC和硫酸盐浓度之间存在明确的、反向的和定量的重要联系。对11个AWMN湖泊的统计分析表明，温度升高、硫沉积减少和海盐负荷变化是DOC变化趋势的主要原因。这些证据表明，大气沉积化学成分的变化，特别是过去20年来人为硫排放的大幅减少，是DOC上升的一个关键原因。如果DOC输出的增加主要与酸沉积的减少有关，而不是与气候变化有关，那么其对碳循环的影响将会非常不同，这表明这些系统可能正在恢复而不是不稳定。
Since 1988, there has been, on average, a 91% increase in dissolved organic carbon (DOC) concentrations of UK lakes and streams in the Acid Waters Monitoring Network (AWMN). Similar DOC increases have been observed in surface waters across much of Europe and North America. Much of the debate about the causes of rising DOC has, as in other studies relating to the carbon cycle, focused on factors related to climate change. Data from our peat-core experiments support an influence of climate on DOC, notably an increase in production with temperature under aerobic, and to a lesser extent anaerobic, conditions. However, we argue that climatic factors may not be the dominant drivers of DOC change. DOC solubility is suppressed by high soil water acidity and ionic strength, both of which have decreased as a result of declining sulphur deposition since the 1980s, augmented during the 1990s in the United Kingdom by a cyclical decline in sea-salt deposition. Our observational and experimental data demonstrate a clear, inverse and quantitatively important link between DOC and sulphate concentrations in soil solution. Statistical analysis of 11 AWMN lakes suggests that rising temperature, declining sulphur deposition and changing sea-salt loading can account for the majority of the observed DOC trend. This combination of evidence points to the changing chemical composition of atmospheric deposition, particularly the substantial reduction in anthropogenic sulphur emissions during the last 20 years, as a key cause of rising DOC. The implications of rising DOC export for the carbon cycle will be very different if linked primarily to decreasing acid deposition, rather than to changes in climate, suggesting that these systems may be recovering rather than destabilising.