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Lake sediments sulfur content

Figure 1. Data from the literature indicate that S concentrations in surface lake sediments are poorly correlated with A, lake-water sulfate concentrations (104 lakes) B, sediment carbon content (78 lakes) or C, sediment iron content (22 lakes). Sulfur concentrations in lake sediments typically are lower than concentrations in marine sediments of comparable carbon content (upper line in B). The lower line in B represents the average C S ratio (55) reported in seston (59, 72, 27, 56, 78). Most of the lake sediments reported in the literature have more iron than sulfur. (Data are from references 24-30, 34, 48—51, 55-57, 59-61, 71, 104, 112, 199, 205, 222, and 223.)... Figure 1. Data from the literature indicate that S concentrations in surface lake sediments are poorly correlated with A, lake-water sulfate concentrations (104 lakes) B, sediment carbon content (78 lakes) or C, sediment iron content (22 lakes). Sulfur concentrations in lake sediments typically are lower than concentrations in marine sediments of comparable carbon content (upper line in B). The lower line in B represents the average C S ratio (55) reported in seston (59, 72, 27, 56, 78). Most of the lake sediments reported in the literature have more iron than sulfur. (Data are from references 24-30, 34, 48—51, 55-57, 59-61, 71, 104, 112, 199, 205, 222, and 223.)...
The studies cited do not clarify what factors determine rates of sulfate reduction in lake sediments. The absence of seasonal trends in reduction rates suggests that temperature is not a limiting factor. Rates of sulfate reduction are not proportional to such crude estimates of carbon availability as sediment carbon content or carbon sedimentation rate, although net reduction and storage of reduced sulfur in sediments often does increase with increasing sediment carbon content. Measured rates of sulfate reduction are not proportional to lake sulfate concentrations, and the relative rates of sulfate reduction and methanogenesis in a variety of lakes do not indicate that sulfate diffusion becomes limiting in eutrophic lakes. Direct comparison of diffusion and reduction rates indicates that diffusion of sulfate into sediments cannot supply sulfate at the rates at which it is reduced. Neither hydrolysis of sulfate... [Pg.336]

Figure 7. Only at the base of sediment cores from 27 lakes is a relationship (r2 = 0.755) observed between the iron content and the fraction of sulfur present as iron sulfides (AVS + CRS). A similar relationship is not observed in surface sediments. As discussed in the text, much of the sulfur at the base of the cores appears to have originated from organic compounds in seston. The relationship may indicate that retention of H2S released during decomposition of seston is determined by the availability of iron. References are... Figure 7. Only at the base of sediment cores from 27 lakes is a relationship (r2 = 0.755) observed between the iron content and the fraction of sulfur present as iron sulfides (AVS + CRS). A similar relationship is not observed in surface sediments. As discussed in the text, much of the sulfur at the base of the cores appears to have originated from organic compounds in seston. The relationship may indicate that retention of H2S released during decomposition of seston is determined by the availability of iron. References are...
If iron limits retention of S in sediments (cf. 50, 30) it would be expected that the fraction of S present as iron sulfides would increase with increasing Fe content of sediments. Although this relationship is observed in deep sediments (Figure 7), fractionation of S between organic and inorganic forms is not determined by iron content in surface sediments. Nor is there any relationship between Fe content and total S content in surface sediments for all lakes reported in the literature (Figure lc). In deep sediments where C S ratios indicate that seston was the major source of sedimentary sulfur... [Pg.356]


See other pages where Lake sediments sulfur content is mentioned: [Pg.181]    [Pg.325]    [Pg.335]    [Pg.90]    [Pg.77]    [Pg.85]    [Pg.87]    [Pg.172]    [Pg.146]    [Pg.192]    [Pg.336]    [Pg.180]    [Pg.75]   
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