Features of Natural Eutrophication of Shallow Lake Nero Based on Sedimentary Pigments

This study analyzes the data of spectrophotometric determination of plant pigments in the bottom sediments of Lake Nero based on bottom survey data of 2017. A low variability (Cᵥ = 27–31%) in concentrations of chlorophyll a and pheopigments over the bottom area and vertically in the sapropel cores is established. The values of pigment concentrations in bottom sediments of the lake belong to the hypertrophic category. The hypertrophic state of the lake with respect to the pigment content (>300 μg/g of dry sediment) is maintained for the period of formation of an 80-cm sapropel layer (~800 years). Trends towards an increase in concentrations of plant pigments from the lower to upper layers of cores are revealed upon a significant relationship with concentrations of organic matter and total nitrogen, which indicates the natural eutrophication of the lake.