Riparian zone control on base cation concentration in boreal streams
Riparian zone control on base cation concentration in boreal streams
复制标题
河岸带对北方溪流中碱阳离子浓度的控制
DOI：
10.5194/bg-10-3849-2013
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发表时间：
2013
期刊：
影响因子：
4.9
通讯作者：
S. Köhler
中科院分区：
文献类型：
--
作者：
J. Ledesma;T. Grabs;M. Futter;K. Bishop;H. Laudon;S. Köhler
河岸带(RZ)是控制森林溪流水化学的主要因素。RZ的盐基阳离子(BC)浓度、通量和循环值得关注，因为气候变化和森林采伐增加可能会对北方地表水产生负面影响，包括重新酸化。我们介绍了一项为期两年的研究，来自瑞典北部一个北方集水区不同景观元素的13个RZ和14个溪流的BC和SiO_2(Si)流量加权浓度。RZ和溪流BC和Si动态的空间差异可以用景观元素类型的差异来解释，粉质沉积物中浓度最高，泥炭为主的湿地地区浓度最低。河岸土壤水中BC和Si浓度的时间稳定性，显著稳定的镁/钙比，以及均匀的矿物学表明，RZ中发现的模式是地下水中明显的矿物学上坡信号的结果。溪水的镁/钙比值表明，该信号随后在溪流中保持不变。水源水中钙、镁和钠的流量加权浓度由RZ中的相应浓度表示，并使用河岸流浓整合模型(RIM)方法进行估算。溪流和RZ径流加权浓度对K和Si的影响不同，表明对这些元素有更强的生物地球化学影响，包括植被对K的再循环和RZ对Si的保留。与森林采伐有关的地下水位的潜在增加或降水制度的变化往往会降低从RZ到溪流的BC浓度，可能导致间歇性酸化。
Riparian zones (RZ) are a major factor controlling water chemistry in forest streams. Base cations' (BC) concentrations, fluxes, and cycling in the RZ merit attention because a changing climate and increased forest harvesting could have negative consequences, including re-acidification, for boreal surface waters. We present a two-year study of BC and silica (Si) flow-weighted concentrations from 13 RZ and 14 streams in different landscape elements of a boreal catchment in northern Sweden. The spatial variation in BC and Si dynamics in both RZ and streams was explained by differences in landscape element type, with highest concentrations in silty sediments and lowest concentrations in peat-dominated wetland areas. Temporal stability in BC and Si concentrations in riparian soil water, remarkably stable Mg/Ca ratios, and homogeneous mineralogy suggest that patterns found in the RZ are a result of a distinct mineralogical upslope signal in groundwater. Stream water Mg/Ca ratios indicate that the signal is subsequently maintained in the streams. Flow-weighted concentrations of Ca, Mg, and Na in headwater streams were represented by the corresponding concentrations in the RZ, which were estimated using the Riparian Flow-Concentration Integration Model (RIM) approach. Stream and RZ flow-weighted concentrations differed for K and Si, suggesting a stronger biogeochemical influence on these elements, including K recirculation by vegetation and retention of Si within the RZ. Potential increases in groundwater levels linked to forest harvesting or changes in precipitation regimes would tend to reduce BC concentrations from RZ to streams, potentially leading to episodic acidification.