Vertical distributions of interstitial phosphate and fluoride in anoxic sediment: Insight into the formation of an authigenic fluoro-phosphorus compound.

Abstract

In order to investigate the chemical form of authigenic phosphate compounds being precipitated in coastal sediments, the vertical distributions of dissolved phosphate and fluoride in pore water from the sediments of Funka Bay (Japan) were determined for the period from April 1997 to July 1998. The phosphate concentration in surface sediment pore water was typically 0-5 µM and increased up to 40-60 µM at 70 cm depth below the surface. In spring and summer, small maximums higher than 100 µM were found at a depth of around 20 cm, probably resulting from decomposition of organic matter and/or desorption of phosphate from the ambient sediment particles under anoxic conditions. Seasonal and vertical variations in the fluoride concentration of the pore water were in the range 53-74 µM. We found an inverse relationship between interstitial phosphate and fluoride concentrations, suggesting precipitation of an authigenic fluoro-phosphorus compound with a P/F atomic ratio of around 1/3 in the sediment. Formation of such a compound will greatly contribute to the global sink of phosphate from the ocean.

Genomes of Two New Ammonia-Oxidizing Archaea Enriched from Deep Marine Sediments

“…The absence of these genes in the deep marine sedimentary AOA metagenome datasets may reflect habitat-specific circumstances. It is likely that sufficient phosphate is available in marine sediment as phosphate levels up to 100 µM were previously noted [51] ; this is 50-fold higher than phosphate concentrations in the marine water column (∼2.0 µM) [52] .…”

Regeneration dynamics of iron and nutrients from bay sediment into bottom water of Funka Bay, Japan

“…The sudden increase in D-Fe and T-Fe concentrations with depth in deep-bottom waters in August 2010 probably resulted from a marked increase in soluble Fe(II) concentrations in anaerobic pore waters near the bay sediment-water interface in addition to the release of the dissolved Fe from biogenic particles, which would be related with DO and nutrient concentrations. In previous study, the oxidation-reduction potential (Eh) values in the sub-surface layer (around 5 cm) of the sediment at Stn 30 of the Funka Bay were from 0 to -50 mV in February and decreased to around -200 mV in April (Sasaki et al 2001). Under the low Eh values in the sub-surface layer, it is possible that the denitrification (CH 2 O (organic carbon)+NO 3 -N 2 +CO 2 ) and the reduction to water-soluble Fe 2+ (CH 2 O+particulate Fe(OH) 3 Fe 2+ +CO ) occur in the anaerobic bay sediment through microbial utilization of oxygen from oxygen-containing compounds such as nitrate and particulate Fe(III) hydroxide, respectively (Stigliani 1988).…”

The Next Generation of Microbial Ecology and Its Importance in Environmental Sustainability

“…Because the organisms being sampled are so small and the microhabitats that can define abundance and distribution are many, the current sampling is often of bulk soil or water that is far from specific. For instance, even within a soil aggregate or at the sediment–water interface where gradients in physical and chemical properties are quite prominent, conditions can go from aerobic (+ 200 mV) at the surface to anaerobic (− 400 mV) in a distance of about 1 mm (e.g., [ 24 , 25 ], thus affecting other processes (e.g., [ 26 , 27 ]). It is difficult not to sample overlapping microhabitats; however, discussion of the intent and shortcomings of sampling should be made clear.…”