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Abstract—First data are reported on the content of plant pigments in bottom sediments of different types in the large shallow Vozhe and Lacha lakes in northwestern Russia. The distribution patterns of chlorophyll a with pheopigments and organic matter in the surface sediments are consistent with sedimentation features. Among the depositional processes, bed erosion, transport of suspended matter, and redeposition dominate in Lake Vozhe, while sedimentation prevails in Lake Lacha. Lake Vozhe is dominated by coarse-grained sediments and shows more pronounced mosaic structure of the sediment complex than Lake Lacha. The lakes show similar values of production indicators for the same type of sediments. Spatial distribution of chlorophyll a and the products of its degradation in the benthal of Lake Vozhe is more heterogeneous than in Lake Lacha. The relative content of the products of chlorophyll degradation in bottom sediments of the studied lakes is about 60%. Average concentration of organic matter calculated considering the areas of bottom sediments of different types in sediments of Lake Vozhe (11.8 ± 2.7%) is 2.3 times less than that of Lake Lacha (27.4 ± 5.5%). The average values of the total content of chlorophyll a and pheopigments characterize Lake Vozhe as a typical mesotrophic water body (38.3 ± 9.3 μg/g dry sediment), and Lake Lacha as an eutrophic basin at the initial stage (72.2 ± 17.7 μg/g dry sediment). The plant carbon calculated from the content of sedimentary pigments amounts an insignificant part of the total primary production of phytoplankton, periphyton, and macrophytes (0.38% in Lake Vozhe and 0.46% in Lake Lacha) and corresponds to 5.3–6.5% of the total organic carbon in bottom sediments. In the absence of anthropogenic pollution, the lakes show signs of eutrophication due to the transboundary transfer and nutrient inflow from the watershed under warming conditions. [ABSTRACT FROM AUTHOR]

An overview of Russian and foreign reference materials of fluorescent properties is presented along with a discussion of the possibility of their use in metrology. A principle of sensitivity analysis for fluorescent instruments based on scaled relative fluorescence units is discussed. Technical and metrological characteristics of a fluorescence gauges kit based on organic dyes with various concentrations developed and certified at the All-Russian Research Institute for Optical and Physical Measurements are given. [ABSTRACT FROM AUTHOR]

New data on the contents of plant pigments and organic matter in bottom sediments of channel, floodplain and estuarine biotopes of the Gorky Reservoir (upstream Volga, Russia) are presented. Patterns of the distribution of sedimentary chlorophyll a and the products of its degradation, pheopigments, depending on the water current velocity, depth and type of the bottom sediments were revealed. Taking into account the zoning of the reservoir by abiotic factors, the trophic conditions in bottom sediments were estimated by the total content of chlorophyll a and pheopigments. Average concentration of sedimentary pigments, calculated considering the areas of bottom sediments of different types, in 2009–2010 (25.3 ± 1.5 μg/g dry sediments) is less than in the years of previous observations, 1996–1998 and 2001 (59.1 and 31.9 ± 3.7 μg/g, respectively). The trophic state of the reservoir's benthal remains mesotrophic. [ABSTRACT FROM AUTHOR]