环境化学
沉积物
水柱
富营养化
深部区域
直接还原铁
化学
浮游植物
环境科学
营养物
海洋学
地质学
古生物学
有机化学
作者
Meret Aeppli,Geoffrey Schladow,Juan S. Lezama Pacheco,Scott Fendorf
标识
DOI:10.1021/acs.est.2c05714
摘要
Increased periods of bottom water anoxia in deep temperate lakes due to decreasing frequency and depth of water column mixing in a warming climate may result in the reductive dissolution of iron minerals and increased flux of nutrients from the sediment into the water column. Here, we assessed the sediment properties and reactivities under depleted oxygen concentrations of Lake Tahoe, a deep ultraoligotrophic lake in the Sierra Nevada mountain range. Using whole-core incubation experiments, we found that a decrease in dissolved oxygen concentration in the top 2 cm of the sediment resulted in an extension of the microbial iron reduction zone from below 4.5 to below 1.5 cm depth. Concentrations of reactive iron generally decreased with sediment depth, and microbial iron reduction seemingly ceased as concentrations of Fe(II) approximated concentrations of reactive iron. These findings suggest that microorganisms preferentially utilized reactive iron and/or iron minerals became less reactive due to mineral transformation and surface passivation. The estimated release of iron mineral-associated phosphorus is not expected to change Lake Tahoe's trophic state but will likely contribute to increased phytoplankton productivity if mixed into surface waters.
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