Delwiche Kyle, Gu Junyao, Hemond Harold, Preheim Sarah P
Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, U.S.A.
Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, MD, U.S.A.
Biogeosciences. 2020;17(12):3135-3147. doi: 10.5194/bg-2019-243. Epub 2020 Jun 19.
Bubbles adsorb and transport particulate matter both in industrial and marine systems. While methane-containing bubbles emitted from anoxic sediments are found extensively in aquatic ecosystems, relatively little attention has been paid to the possibility that such bubbles transport particle-associated chemical or biological material from sediments to surface waters of freshwater lakes. We quantified transport of particulate material from sediments to the surface by bubbles in Upper Mystic Lake, MA and in a 15 m tall experimental column. Vertical particle transport was positively correlated with the volume of gas bubbles released from the sediment. Particles transported by bubbles originated almost entirely in the sediment, rather than being scavenged from the water column. Concentrations of arsenic, chromium, lead, and cyanobacterial cells in bubble-transported particulate material were similar to those of bulk sediment, and particles were transported from depths exceeding 15 m, resulting in daily fluxes as large as 0.18 mg of arsenic m and 2 × 10 cyanobacterial cells m in the strongly stratified Upper Mystic Lake. While bubble-facilitated arsenic transport currently appears to be a modest component of total arsenic cycling in this lake, bubble-facilitated cyanobacterial transport could comprise as much as 17% of recruitment in this lake and may thus be of particular importance in large, deep, stratified lakes.
在工业和海洋系统中，气泡都会吸附和运输颗粒物。虽然缺氧沉积物释放的含甲烷气泡在水生生态系统中广泛存在，但对于此类气泡将与颗粒相关的化学或生物物质从沉积物运输到淡水湖泊表层水的可能性，人们关注相对较少。我们对马萨诸塞州上神秘湖以及一个15米高的实验柱中气泡将颗粒物从沉积物运输到表层的情况进行了量化。垂直颗粒运输与沉积物释放的气泡体积呈正相关。由气泡运输的颗粒几乎完全源自沉积物，而非从水柱中 scavenged（此处可能有误，推测是scavenged，意为 scavenged from the water column 从水柱中捕获，应翻译为“捕获”）而来。气泡运输的颗粒物中砷、铬、铅和蓝藻细胞的浓度与沉积物总体的浓度相似，并且颗粒从超过15米的深度被运输，这导致在强烈分层的上神秘湖中日通量高达每平方米0.18毫克砷和每平方米2×10个蓝藻细胞。虽然目前气泡促进的砷运输在该湖总砷循环中似乎占比较小，但气泡促进的蓝藻运输可能占该湖蓝藻补充量的17%，因此在大型、深水、分层湖泊中可能尤为重要。
