Environment Canada, Science and Technology Branch, 105 McGill St., Montreal, QC, Canada H2Y 2E7.
Environ Sci Pollut Res Int. 2012 Feb;19(2):361-71. doi: 10.1007/s11356-011-0565-6. Epub 2011 Jul 14.
Increases in dissolved organic carbon (DOC) concentrations have been reported in surface waters worldwide in the last 10 to 20 years. The causes behind these increases have been attributed to many factors, including climate change and decreasing depositions of atmospheric sulphate (SO₄²⁻). Trends in DOC concentrations and their potential causal factors were examined in a network of 30 lakes lying in undisturbed temperate and boreal catchments in the province of Quebec, Canada.
Temporal trends in lake DOC concentrations were analysed with the seasonal Kendall test. For each lake, the variation in DOC concentration over time was assessed in light of the variation in SO₄²⁻ concentration in precipitation, air temperature, precipitation and solar radiation using the forward stepwise multiple regression.
Between 1989 and 2006, significant increases in DOC were observed in most of the lakes, the mean rate of change being 0.05 mg L(-1) year(-1). Lake DOC concentrations were significantly explained by different models that yielded a variance explanation ranging from 13% to 77%. The models included long-term temperature variables (i.e. averaged over intervals of 10 years), short-term precipitation variables (i.e. summed over intervals 6 months), radiation (i.e. ice-free period prior to the DOC observation) and precipitation SO₄²⁻ concentration as explanatory variables.
Temporal changes in DOC concentrations seem more consistent with the evolution of climate parameters rather than SO₄²⁻ concentrations despite the fact that most lakes were in the process of recovery, showing increases in pH.
在过去的 10 到 20 年中，全球地表水的溶解有机碳 (DOC) 浓度有所增加。这些增加的原因可归因于多种因素，包括气候变化和大气硫酸盐 (SO₄²⁻) 沉积减少。本研究在加拿大魁北克省未受干扰的温带和北方地区的 30 个湖泊网络中，检查了 DOC 浓度的趋势及其潜在的因果因素。
使用季节性 Kendall 检验分析湖泊 DOC 浓度的时间趋势。对于每个湖泊，根据降水、气温、降水和太阳辐射中 SO₄²⁻浓度的变化，使用逐步向前多元回归评估 DOC 浓度随时间的变化。
在 1989 年至 2006 年期间，大多数湖泊的 DOC 显著增加，平均变化率为 0.05mgL⁻¹year⁻¹。湖泊 DOC 浓度由不同的模型显著解释，这些模型的方差解释范围从 13%到 77%不等。模型包括长期温度变量（即 10 年平均值）、短期降水变量（即 6 个月总和）、辐射（即 DOC 观测前的无冰期）和降水 SO₄²⁻浓度作为解释变量。
尽管大多数湖泊处于恢复过程中，pH 值升高，但 DOC 浓度的时间变化似乎与气候参数的演变更为一致，而不是与 SO₄²⁻浓度的演变更为一致。
