Jellyfish Lake, Palau: Regeneration of C, N, Si, and P in anoxic marine lake sediments

Abstract

Sediment cores from Jellyfish Lake were processed under an inert atmos phcre and the pore waters extracted and analyzed for the following parameters: pH, titration alkalinity (TA), Cl-, H4Si04, POd3-, NH4+, Ca2+, Mg2+, SOd2-, and H2S. Additionally, in one set of pore-water samples (core lo), the 613C of the X0, was also determined. The TA, H4Si04, POd3-, NH;+, and H,S increased with depth in the pore waters above anoxic bottom-water values. H,S values increased to 3.8 PM. In one case, both H,SiO, and POd3-concentrations increased to a maximum value and then decreased with depth, suggesting removal into solid phases. The H,SiO, concentrations are equal to or greater than pore-water values observed in sediments underlying upwelling areas. Pod3 -concentrations are, in general, lower than pore-water values from terrigenous nearshore areas but higher than nearshore carbonate pore-water values from Florida Bay or Bermuda. The Ca2+, Cl-, and Mg2+ : Cl-ratios show slight decreases in the top 15-20 cm, suggesting that authigenic carbonate may be forming. This suggestion is supported by the fact that the pore waters are saturated with respect to CaCO, due to the very high TAs. The 613C measurements of the pore-water X0, are from a shorter core. These measurements reach their most negative concentration at 72 cm and tilen become slightly heavier. This change is accompanied by a decrease in TA, suggesting the onset of methanogenesis at this location in this core.l Present address:

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

“…The lower DF concentration was chiefly found in the subsurface layer during spring and summer corresponding with a higher DRP concentration. Such lower concentrations of DF in the pore water of marine sediments have been reported for other coastal regions (Ruttenberg and Berner, 1993) and for a saline water lake (Lyons et al, 1996). In these observations, contemporaneous high concentrations of DRP in the pore water were also found.…”

“…The phosphorus to fluorine (P/F) atomic ratio of CFA has been reported to be in the range 2/1-5/1 (Parker, 1975;Burnett, 1977;Jahnke, 1984;Gulbrandsen et al, 1984;Baker and Burnett, 1988;Froelich et al, 1988). Although it has been suggested that CFA forms in reductive non-phosphogenic sediment (Sundby et al, 1992;Lyons et al, 1996;Louchouarn et al, 1997), the existence of CFA has not been confirmed in such sediment. Phosphorus contents of marine sediment are generally less than 1000 ppm making the contents difficult to analyze by either nondestructive analysis (such as X-ray diffraction) or isolation of the mineral for chemical analysis (e.g., Ruttenberg and Berner, 1993).…”

“…The slope of the line is -0.30 ± 0.03. The data indicates that the phosphorus to fluorine atomic ratio (i.e., g/h) in the authigenic mineral is (Ruttenberg and Berner, 1993) and from Jellyfish Lake (Lyons et al, 1996), respectively. around 1/3.…”

“…The P/F atomic ratio is often used to calculate the burial flux of phosphorus (Lyons et al, 1996;Reimers et al, 1996) and hence to calculate the effective phosphorous sink. The vertical and seasonal variation in dissolved reactive phosphate in marine sediment pore water will yield information concerning the precipitation of authigenic phosphate minerals in the sediment.…”

Primary Production, Community Respiration, and Net Community Production along Oxygen and Nutrient Gradients: Environmental Controls and Biogeochemical Feedbacks within and across “Marine Lakes”

“…In both NLK and OTM, low CR and high NCP near the chemocline suggest a substantial flux of organic matter from the upper portion of the lake into deeper layers. However, Lyons et al (1996) estimated that in OTM only 4% of autochthonous organic matter is deposited on the lake bottom, with vertical stratification slowing the decent of phytoplankton-derived organic matter.…”