Environmental and Life Sciences Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON K9J7B8, Canada.
Sci Total Environ. 2011 Mar 1;409(7):1235-42. doi: 10.1016/j.scitotenv.2010.12.027. Epub 2011 Jan 14.
Peatlands are large repositories of atmospheric carbon and concern has been raised over the stability of this carbon store because increasing dissolved organic carbon (DOC) concentrations have been observed in peatland drainage waters. A number of potential causes have been proposed in the literature, and conflicting results among studies conducted at different spatial and temporal scales suggest that the methodological approach may be an important confounding factor. The objective of this study was to determine the influence of moisture and temperature on DOC release from a south-central Ontario peatland during the fall (a major export period) following three commonly used approaches: laboratory microcosms, an intensive field study and analysis of long-term data (1980-2008). The effect of variations in temperature and moisture differed among microcosm, field study and analysis of the long-term record. Water content was important at the microcosm scale as DOC concentration and aromaticity increased with peat water-saturation. Drought caused a decrease in DOC concentration and pH, and an increase in sulphate and base cation concentrations. In contrast, the field study indicated that DOC concentration was strongly associated with temperature, and weakly correlated (negatively) with stream discharge. Average fall DOC concentration (but not export) increased over the 29 year record, and was correlated with fall discharge and precipitation (negative) and summer precipitation and fall stream pH (positive). As no common strong predictor of fall DOC was found at three scales of investigation at a single, well-studied site, it may be unreasonable to expect to identify a universal driver behind the widespread increase in DOC concentration.
泥炭地是大气碳的巨大储存库，人们对这种碳储存的稳定性表示担忧，因为已经观察到泥炭地排水水中溶解有机碳 (DOC) 浓度的增加。文献中提出了许多潜在的原因，而在不同时空尺度上进行的研究结果相互矛盾，这表明方法学方法可能是一个重要的混杂因素。本研究的目的是确定在安大略省中南部泥炭地秋季（主要的输出期），在三种常用方法（实验室微宇宙、密集野外研究和长期数据（1980-2008 年）分析）下，水分和温度对 DOC 释放的影响。在微宇宙、野外研究和长期记录分析中，温度和水分的变化对 DOC 释放的影响不同。水含量在微宇宙尺度上很重要，因为 DOC 浓度和芳构度随着泥炭水分饱和而增加。干旱导致 DOC 浓度和 pH 值降低，硫酸盐和碱基阳离子浓度增加。相比之下，野外研究表明，DOC 浓度与温度密切相关，与溪流流量（负相关）和流量（负相关）与夏季降水和秋季溪流 pH 值（正相关）弱相关。由于在单个研究充分的地点的三个调查尺度上没有找到秋季 DOC 的共同强预测因子，因此期望确定 DOC 浓度普遍增加背后的普遍驱动因素可能是不合理的。
