ABSTRACT

Humic lakes play a key role in the processing of organic carbon (OC) mobilised from their catchments, but knowledge of OC dynamics in lakes within maritime temperate climates is limited. Climate exerts a significant influence on mechanisms of OC capture, storage, and processing on the wet and cloudy west coast of Ireland. We examined a high-frequency dataset of partial pressure of CO₂ (pCO₂) in the surface waters of Lough Feeagh collected over 1 year. The annual pattern in pCO₂ ranged between 491 and 1169 µatm and was strongly related to allochthonous riverine OC inputs. In contrast to observations in colder climates, a single peak in pCO₂ occurred in Lough Feeagh in early September. Generalised additive mixed modelling revealed that 2 variables, inflow water colour concentration (a reliable proxy for DOC concentrations) and lake Schmidt stability, together explained 68% of pCO₂ variability. Both the statistical analysis and timing of the peaks in inflow DOC and pCO₂ strongly suggested that catchment carbon export drove pCO₂ supersaturation in the lake, and hence CO₂ emissions. We estimated that between 217 and 370 t CO₂-C (0.55–0.94 t/ha) was emitted during the study period. These results highlight the interplay between catchment OC fluxes and climate in determining pCO₂ dynamics in maritime temperate lakes.

摘要

腐殖质湖泊在从其集水区动员的有机碳 (OC) 的加工过程中发挥着关键作用，但对海洋温带气候下湖泊中有机碳动态的了解是有限的。气候对爱尔兰潮湿多云的西海岸的 OC 捕获、储存和加工机制产生重大影响。我们检查了超过 1 年收集的 Lough Feeagh 地表水中CO ₂ ( p CO ₂ )分压的高频数据集。p CO ₂的年度模式介于 491 和 1169 µatm 之间，并且与外来河流 OC 输入密切相关。与在较冷气候下的观察结果相反，p CO ₂的单峰9 月初发生在 Lough Feeagh。广义加性混合模型显示，流入水色浓度（DOC 浓度的可靠代表）和施密特湖稳定性这两个变量共同解释了p CO ₂变异性的68% 。流入 DOC 和p CO ₂峰值的统计分析和时间都强烈表明集水区碳输出导致湖中p CO ₂过饱和，从而导致 CO ₂排放。我们估计 217 至 370 吨 CO ₂-C (0.55–0.94 t/ha) 在研究期间排放。这些结果突出了集水区 OC 通量和气候之间在确定海洋温带湖泊中p CO ₂动态方面的相互作用。