National Marine Science Centre, Southern Cross University, Coffs Harbour, New South Wales, Australia; School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia.
School of Environment, Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia; Southern Cross Geoscience, Southern Cross University, Lismore, New South Wales, Australia.
Sci Total Environ. 2021 Jul 10;777:146124. doi: 10.1016/j.scitotenv.2021.146124. Epub 2021 Mar 1.
The small-scale spatial variability in dissolved carbon dioxide (CO) and water-air CO flux dynamics were investigated within first-order catchments of the upper Blue Mountains Plateau (New South Wales, Australia). Water samples were collected at 81 locations during winter and summer over two consecutive years across seven aquatic ecosystem types: wetland, impoundment, lake, tributary stream, mainstem, escarpment complex, and urban-aquatic interface. Dissolved [CO] ranged from 15 to 880 μM (94 to 4760%Sat), and dissolved [O] from 0 to 350 μM (0 to 101%Sat). CO supersaturation was typically highest in wetlands and vegetated impoundments of the upper plateau, and decreased downstream approaching atmospheric equilibrium at the escarpment waterfalls. Gas transfer velocities ranged from 0.18 m d in lentic waters to 292 m d at the bottom of waterfalls due to bubble-mediated transfer. The first- and second-order streams represented only 4.8% of the total open water area yet contributed to 61% of the total water-air CO outgassing. The lake, escarpment and mainstem group systems had narrow diel and seasonal CO concentration variability, while wetlands and vegetated impoundments had the widest ranges. Our high resolution spatio-temporal sampling was essential to identifying CO outgassing hotspots in these geomorphically diverse catchments. Overall, >95% of excess dissolved CO traversing the upper Blue Mountains Plateau was outgassed to the atmosphere.
本研究调查了澳大利亚新南威尔士州蓝山高原上游一级流域中溶解二氧化碳（CO）和水-气 CO 通量动态的小规模空间变异性。在连续两年的两个冬季和夏季，在七个水生态系统类型（湿地、水坝、湖泊、支流溪流、干流、悬崖复合体和城市-水界面）的 81 个位置采集了水样。溶解[CO]的范围从 15 到 880 μM（94 到 4760%Sat），溶解[O]的范围从 0 到 350 μM（0 到 101%Sat）。CO 过饱和度通常在高原上部的湿地和植被水坝中最高，并且随着接近悬崖瀑布的大气平衡，沿下游逐渐降低。由于气泡介导的转移，气体转移速度从静水水域的 0.18 m d 到瀑布底部的 292 m d 不等。第一级和第二级溪流仅占总开放水域面积的 4.8%，但贡献了总水-气 CO 排放的 61%。湖泊、悬崖和干流系统的 CO 浓度昼夜和季节变化范围较窄，而湿地和植被水坝的变化范围最宽。我们的高分辨率时空采样对于确定这些地貌多样的流域中的 CO 排放热点至关重要。总体而言，穿过蓝山高原上游的超过 95%的过量溶解 CO 被排放到大气中。
