Variation in the sensitivity of DOC release between different organic soils following H2SO4 and sea-salt additions
Variation in the sensitivity of DOC release between different organic soils following H2SO4 and sea-salt additions
复制标题
添加 H2SO4 和海盐后不同有机土壤之间 DOC 释放敏感性的变化
DOI：
10.1111/j.1365-2389.2010.01344.x
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发表时间：
2011
影响因子：
4.2
通讯作者：
Clark J
中科院分区：
文献类型：
--
作者：
Clark J
北美东部和欧洲的长期监测数据表明，过去二十年来，地表沃茨中溶解有机碳（DOC）浓度的增加与大气污染物和海洋硫（S）沉积的减少之间存在联系。这一假设是，降低酸度和离子强度与下降的S沉积增加了DOC的溶解度。然而，DOC趋势的迹象和幅度不同的网站之间，在某些情况下，在S沉积下降的网站，DOC没有显着增加已被观察到，造成不确定性的因果机制驱动观察到的趋势。在本文中，我们证明了DOC释放的化学调节有机土壤在批量实验中引起的酸度和电导率的变化（测量作为离子强度的代理）与控制SO42 −添加。在20小时的提取期内，添加0 - 437 µ eq SO42 − l − 1硫酸（H2SO4）和中性海盐溶液（含有Na+、Mg2+、Cl −、SO42 −），有机矿质土壤和泥炭的O层顶部10 cm处DOC释放量下降了21 - 60%。在大多数但不是所有土壤中，随着酸度的增加，酸敏感的有色芳香族腐殖酸的比例（通过254 nm处的特定紫外吸光度（苏瓦）测量）也显着下降（P <0.05），证实DOC质量以及数量随着SO42 −的增加而变化。DOC释放似乎是更敏感的酸度比电导率增加。通过比较DOC释放的变化与散装土壤性质，我们发现，DOC释放从O-层的有机矿质土壤和半封闭泥炭，其中含有更多的交换性铝（Al）和较低的盐基饱和度（BS），更敏感的SO42-添加比DOC释放从毯泥炭与低浓度的交换性铝和更大的BS。因此，在土壤类型和酸/碱状态的网站之间的变化可能部分解释DOC的变化幅度的差异，在不同的网站，在S沉降下降已经相似。
Long‐term monitoring data from eastern North America and Europe indicate a link between increased dissolved organic carbon (DOC) concentrations in surface waters over the last two decades and decreased atmospheric pollutant and marine sulphur (S) deposition. The hypothesis is that decreased acidity and ionic strength associated with declining S deposition has increased the solubility of DOC. However, the sign and magnitude of DOC trends have varied between sites, and in some cases at sites where S deposition has declined, no significant increase in DOC has been observed, creating uncertainty about the causal mechanisms driving the observed trends. In this paper, we demonstrate chemical regulation of DOC release from organic soils in batch experiments caused by changes in acidity and conductivity (measured as a proxy for ionic strength) associated with controlled SO42−additions. DOC release from the top 10 cm of the O‐horizon of organo‐mineral soils and peats decreased by 21–60% in response to additions of 0–437 µeq SO42−l−1sulphuric acid (H2SO4) and neutral sea‐salt solutions (containing Na+, Mg2+, Cl−, SO42−) over a 20‐hour extraction period. A significant decrease in the proportion of the acid‐sensitive coloured aromatic humic acids (measured by specific ultra‐violet absorbance (SUVA) at 254 nm) was also found with increasing acidity (P< 0.05) in most, but not all, soils, confirming that DOC quality, as well as quantity, changed with SO42−additions. DOC release appeared to be more sensitive to increased acidity than to increased conductivity. By comparing the change in DOC release with bulk soil properties, we found that DOC release from the O‐horizon of organo‐mineral soils and semi‐confined peats, which contained greater exchangeable aluminium (Al) and had lower base saturation (BS), were more sensitive to SO42−additions than DOC release from blanket peats with low concentrations of exchangeable Al and greater BS. Therefore, variation in soil type and acid/base status between sites may partly explain the difference in the magnitude of DOC changes seen at different sites where declines in S deposition have been similar.