Organic matter mineralization rates in sediments: a within- and among-lake study

Article Abstract:

Nine Quebec lakes were studied to determine rates of organic matter mineralization, measured by accumulation of dissolved inorganic carbon (DIC) and CH4. Areal carbon mineralization shows greater variability within lakes than among lakes of varying trophic richness. Littoral sediments have more variable and higher rates of organic matter mineralization than profundal sediments. Site depth explains 60% of variation in mean summer mineralization rates. Water residence time and the ratio of catchment area to lake area are the variables most strongly correlated to residuals of the regression with depth.

Water chemistry, Carbon cycle (Biogeochemistry), Carbon cycle

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Sediment accumulation and Pb burdens in submerged macrophyte beds

Article Abstract:

The effect of lake morphometry and submerged macrophyte beds on accumulation of sediments in the littoral zone is discussed as it relates to quantification based on stable lead (Pb), a historical marker of lacustrine sediments in southern Quebec. Three long-term sediment accumulation rates in Lake Memphremagog (Quebec-Vermont) were calculated. Anthropogenic Pb burden in the littoral zone was 2-8 times as great as Pb burden in the profundal zone of nearby eastern township lakes of Quebec with Pb concentrations higher by a factor of 4 than background Pb concentrations.

Vermont, Statistical Data Included, Lead, Environmental aspects, Lakes, Lake ecology, Aquatic plants, Shorelines

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A direct comparison between the historical record of lake level and the delta18-O signal in carbonate sediments from Lake Turkana, Kenya

Article Abstract:

A comparison between the historical record and delta18-O in sediments from Lake Turkana, Kenya, indicates that records of delta18-O can be used to create quantitative lake level curves. Spatial variability occurred in delta18-O and delta13-C values of the cores, and the variability was correlated with proximity to river input. A normalized and stacked record was used to mute the spatial variability in model calculations of lake level, and a good agreement was obtained between the modeled lake level history and the historical record.

Kenya, Oxygen, Oxygen isotopes, Carbonates, Lake Turkana

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