Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70808, USA.
Department of Oceanography and Coastal Sciences, College of the Coast and Environment, Louisiana State University, Baton Rouge, LA 70808, USA.
Sci Total Environ. 2019 Feb 15;651(Pt 1):122-133. doi: 10.1016/j.scitotenv.2018.09.031. Epub 2018 Sep 7.
The interactions between the microbial reduction of Fe (III) oxides and sediment geochemistry are poorly understood and mostly unknown for the Louisiana deltaic plain. This study evaluates the potential of P mobilization for this region during bacterially mediated redox reactions. Samples were collected from two wetland habitats (forested wetland ridge, and marsh) characterized by variations in vegetation structure and elevation in the currently prograding Wax Lake Delta (WLD) and two habitats (wetland marsh, and benthic channel) in degrading Barataria Bay in Lake Cataouatche (BLC). Our results show that PO mobilization from WLD and BLC habitats were negligible under aerobic condition. Under anaerobic condition, there is a potential for significant release of PO from sediment and wetland soils. PO release in sediments spiked with Fe reducing bacteria Shewanella putrefaciens (Sp-CN32) were significantly higher in all cases with respect to a control treatment. In Wax Lake delta, PO release from sediment spiked with Sp-CN32 increased significantly from 0.064±0.001 to 1.460±0.005μmolg in the ridge and from 0.079±0.007 to 2.407±0.001μmolg in the marsh substrates. In Barataria bay, PO release increased from 0.103±0.006μmolg to 0.601±0.008μmolg in the channel and 0.050±0.000 to 0.618±0.026μmolg in marsh substrates. The PO release from sediment slurries spiked with Sp-CN32 was higher in the WLD habitats (marsh 30-fold, ridge 22-fold) compared to the BLC habitats (marsh 12-fold, channel 6-fold). The increase in PO release was significantly correlated with the Fe bound PO in sediments from different habitats but not with their organic matter content. This study contributes to our understanding of the release mechanism of PO during bacterial mediated redox reaction in wetland soils undergoing pulsing sediment deposition and loss.
微生物还原 Fe(III)氧化物与沉积物地球化学之间的相互作用知之甚少，在路易斯安那三角洲平原更是几乎不为人知。本研究评估了在细菌介导的氧化还原反应过程中，该地区磷释放的潜力。样品取自两个湿地生境（林地湿地脊和沼泽），其植被结构和当前推进的 Wax Lake 三角洲（WLD）的海拔高度存在差异，以及两个生境（湿地沼泽和海底通道）在退化的 Barataria 湾在 Lake Cataouatche（BLC）。我们的研究结果表明，在有氧条件下，WLD 和 BLC 生境中的 PO 释放可忽略不计。在厌氧条件下，沉积物和湿地土壤中可能会有大量 PO 释放。在添加铁还原细菌 Shewanella putrefaciens（Sp-CN32）的沉积物中，PO 的释放与对照处理相比，所有情况下都明显升高。在 Wax Lake 三角洲，从 Sp-CN32 接种的沉积物中释放的 PO 分别从山脊中的 0.064±0.001 显著增加到 1.460±0.005μmolg，从沼泽基质中的 0.079±0.007 增加到 2.407±0.001μmolg。在 Barataria 湾，从 0.103±0.006μmolg 增加到 0.601±0.008μmolg 时，通道中的 PO 释放增加，沼泽基质中的 0.050±0.000 增加到 0.618±0.026μmolg。与 BLC 生境（沼泽 12 倍，通道 6 倍）相比，WLD 生境（沼泽 30 倍，山脊 22 倍）中添加 Sp-CN32 的沉积物悬浮液中 PO 的释放量更高。PO 释放量的增加与不同生境沉积物中结合态 PO 显著相关，但与有机质含量无关。本研究有助于我们理解在经历脉冲沉积和损失的湿地土壤中，细菌介导的氧化还原反应过程中 PO 释放的机制。
