Microbial cycling contributes to the release of dissolved inorganic phosphate into the groundwater of floodplain aquifers

Little is known about biological processes controlling inorganic phosphate (PO4) in groundwater ecosystems. Here we present analyses of groundwater samples from the Hetao Basin, China that show an increasing contribution of microbial cycling to groundwater PO4 from oxic to anoxic conditions along a...

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Bibliographic Details
Published in:Communications earth & environment 2024-09, Vol.5 (1), p.494-13, Article 494
Main Authors: Li, Yao, Neidhardt, Harald, Guo, Huaming, Nagel, Christiane, Shao, Wen, Yu, Chen, Zhao, Bo, Chen, Dou, Xiu, Wei, Oelmann, Yvonne
Format: Article
Language:English
Subjects:
Anoxic conditions
Apatite
Aquifers
Bacteria
Biological activity
Cycles
Floodplains
Groundwater
Groundwater flow
Iron
Isotope ratios
Isotopes
Microorganisms
Oxygen isotope ratio
Oxygen isotopes
Redox properties
Sediment samplers
Sulfate reduction
Sulfate-reducing bacteria
Water analysis
Water sampling
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Summary:Little is known about biological processes controlling inorganic phosphate (PO4) in groundwater ecosystems. Here we present analyses of groundwater samples from the Hetao Basin, China that show an increasing contribution of microbial cycling to groundwater PO4 from oxic to anoxic conditions along a flow path with phosphate-bound oxygen isotopes (δ18OPO4). Under oxic conditions, although 25–47% of the dissolved PO4 inherited the initial source signal of igneous apatite, groundwater δ18OPO4 reflected a pronounced impact of intracellular enzymatic cycling. Under anoxic conditions, dissolved PO4 carried a nearly exclusive equilibrium isotope signal, which was probably due to (i) release of PO4 with an equilibrium δ18OPO4 from Fe(III) oxides, as a result of Fe(III) reduction in the presence of Fe(III)- and sulfate-reducing bacteria; and/or (ii) cumulative microbial cycling of dissolved PO4 with increasing groundwater residence time. Our study highlights that PO4 in groundwater is tightly microbially cycled under a wide range of redox conditions and microbial cycling contributes to the release of PO4 in groundwater.The contribution of microbial phosphorus cycling to the dissolved phosphate concentration increases along a groundwater flow path from oxic to anoxic conditions, according to groundwater and sediment sampling in the Hetao Basin, China and stable oxygen isotope ratio analysis.
ISSN:2662-4435
2662-4435
DOI:10.1038/s43247-024-01666-3