The influence of summer seasonal extremes on dissolved organic carbon export from a boreal peatland catchment: evidence from one dry and one wet growing season.
The influence of summer seasonal extremes on dissolved organic carbon export from a boreal peatland catchment: evidence from one dry and one wet growing season.
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DOI：
10.1016/j.scitotenv.2008.10.005
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
D. F. Jager;M. Wilmking;J. Kukkonen
中科院分区：
文献类型：
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作者：
D. F. Jager;M. Wilmking;J. Kukkonen
在芬兰东部的一个小泥炭地集水区进行了监测径流和出口的溶解有机碳。为了验证泥炭地在不同气象条件下的响应，提供了一个非常干燥和一个潮湿的生长季节的数据。径流量分别为194和387 mm，DOC输出量分别为4.2和11.3 gC m− 2。水文过程分析表明，在这两年中，最径流和DOC输出产生在高峰流量事件，低基流在中间时期。降雨事件的径流响应是最强的高水位下，在春季和秋季，夏季径流最小。干旱对径流的影响只发生在6月中旬后，当时融雪的影响已经消失。因此，融雪占主导地位的DOC输出在干燥的一年（61%），但贡献少得多（29%）在潮湿的一年。径流和地下水位之间的关系是非常相似的，在这两年。在此观察到的任何变化都可能与夏季干燥条件下泥炭表面的表面沉降和泉水水位升高有关，从而导致洪水导致排水受限。DOC浓度在这两年中观察到的变化一般有DOC输出的影响有限。在高峰径流事件，浓度下降成比例的事件的大小。这种可用DOC的减少被认为是由主导的供应和生产的淋溶和泥炭地表面的特定水力特性。在干旱条件下，DOC浓度高出约25%。这些高浓度被消除春季融雪的第二年，表明冬季积雪在北方地区可能有助于限制长期的水文和生化影响的干旱。
A small peatland catchment in eastern Finland was monitored for runoff and export of dissolved organic carbon. To exemplify the response of a peatland under years of different meteorological conditions, data from one very dry and one wet growing season are presented. Runoff was 194 and 387 mm, and DOC export was 4.2 and 11.3 gC m−2in the dry and wet year respectively. Analysis of the hydrographs showed that in both years most runoff and DOC export was generated during peak flow events, with low baseflow in the intermediate periods. Runoff response to rain events was strongest under a high water table in the spring and autumn, with a summer runoff minimum. The effect of drought on runoff occurred only after mid June when the effects of snowmelt had dissipated. Snowmelt therefore dominated DOC export in the dry year (61%) but contributed much less (29%) in the wet year. The relationship between runoff and the water table was highly similar in both years. Any variation that was observed herein was potentially related to a superficial subsidence of the peat surface under drier summer conditions and to raised spring water levels, causing restricted drainage due to flooding. The observed variation of DOC concentrations in both years generally had a limited impact on DOC export. During peak runoff events, concentrations dropped proportionally to the magnitude of the events. This decrease in available DOC is argued to be caused by a dominance of leaching over supply and production and by the specific hydraulic characteristics of the peatland surface. DOC concentrations were some 25% higher under drought conditions. These elevated concentrations were dispelled by spring snowmelt of the next year, demonstrating that a winter snowpack in boreal regions may be instrumental in limiting the longer term hydrological and biochemical effects of a drought.