Science and Technology Branch, Environment Canada and Climate Change, 105 McGill St., QC, H2Y 2E7 Montreal, Canada.
Science and Technology Branch, Environment Canada and Climate Change, 105 McGill St., QC, H2Y 2E7 Montreal, Canada.
Sci Total Environ. 2020 Dec 10;747:141539. doi: 10.1016/j.scitotenv.2020.141539. Epub 2020 Aug 6.
In the last decades, a worldwide increase in dissolved organic carbon (DOC) concentrations has been observed in temperate and boreal lakes. This phenomenon has several detrimental effects on the aquatic life and affect local C geochemical cycles. In this study, we measured DOC concentration in the water column of 36 lakes located in eastern Canada over a period of 35 years (1983-2017) and assessed the influence of climatic, hydrologic and morphometric variables on both DOC concentrations and on the rate of DOC changes (∆DOC). Our data show that morphometric and hydrologic variables have a stronger direct influence on lake water DOC concentrations than vegetation and climatic variables. DOC concentration strongly increased with the drainage ratio and the surface covered by organic deposits, which together explained 59% of the variance. As expected, we observed a significant increase in lake water DOC concentration in 72% of the surveyed lakes, which averaged 20% over the study period. Meanwhile, lake water SO concentration decreased by 60%. ∆DOC was poorly influenced by the rate of changes in lake water SO as well as by the rate of changes in mean annual air temperature and precipitation. ∆DOC was more related to the vegetation type and the morphometry of the catchment: a model including the percentage of conifers, terrestrial catchment area and ∆Cl yielded a variance explanation of 39%. This shows that the rate of increase was primarily driven by morphometric variables which did not change over the study period.
在过去的几十年里，人们观察到在温带和北方湖泊中溶解有机碳 (DOC) 的浓度在全球范围内有所增加。这一现象对水生生物有许多不利影响，并影响当地的碳地球化学循环。在这项研究中，我们测量了 36 个位于加拿大东部的湖泊水柱中的 DOC 浓度，时间跨度为 35 年（1983-2017 年），并评估了气候、水文和形态变量对 DOC 浓度和 DOC 变化率（∆DOC）的影响。我们的数据表明，形态和水文变量对湖泊水中 DOC 浓度的直接影响大于植被和气候变量。DOC 浓度与排水比和有机沉积物覆盖的表面积呈强烈正相关，这两个变量共解释了 59%的方差。正如预期的那样，我们观察到在 72%的受调查湖泊中，湖水 DOC 浓度显著增加，在研究期间平均增加了 20%。与此同时，湖水 SO浓度下降了 60%。∆DOC 受湖水 SO 变化率以及年平均气温和降水变化率的影响较小。∆DOC 与植被类型和集水区形态更为相关：一个包含针叶树百分比、陆地集水区面积和 ∆Cl 的模型可以解释 39%的方差。这表明，增长率主要由形态变量驱动，而这些变量在研究期间没有变化。
