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Title: Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake
Creator(s): Aullo-Maestro, María Encina
Hunter, Peter
Spyrakos, Evangelos
Mercatoris, Pierre
Kovacs, Attila W
Horvath, Hajnalka
Preston, Tom
Presing, Matyas
Torres Palenzuela, Jesus M
Tyler, Andrew
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Keywords: Chromophoric dissolved organic matter (CDOM)
Bio-optical properties
Spectral absorption
Lake Balaton
Date Available: 12-Aug-2016
Citation: Aulló-Maestro, M; Hunter, P; Spyrakos, E; Mercatoris, P; Kovács AW; Horváth, H; Preston, T; Présing, M; Torres Palenzuela, JM; Tyler A (2016): Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake. University of Stirling. Dataset.
Publisher: University of Stirling
Dataset Description (Abstract): The development and validation of remote sensing-based approaches for the retrieval of CDOM concentrations requires a comprehensive understanding of the sources and magnitude of variability in the optical properties of dissolved material within lakes. In this study, spatial and seasonal variability in concentration and composition of CDOM and the origin of its variation was studied in Lake Balaton (Hungary), a large temperate shallow lake in central Europe. In addition, we investigated the effect of photobleaching on the optical properties of CDOM through in-lake incubation experiments. There was marked variability throughout the year in CDOM absorption in Lake Balaton (aCDOM (440) = 0.06 - 9.01 m-1). The highest values were consistently observed at the mouth of the main inflow (River Zala), which drains humic-rich material from the adjoining Kis-Balaton wetland, but CDOM absorption decreased rapidly towards the east where it was consistently lower and less variable than in the westernmost lake basins. The spectral slope parameter for the interval of 350–500 nm (SCDOM(350–500)) was more variable with increasing distance from the inflow (observed range 0.0161-0.0181 nm-1 for the mouth of the main inflow and 0.0158-0.0300 nm-1 for waters closer to the outflow). However, spatial variation in SCDOM was more constant exhibiting a negative correlation with aCDOM(440). DOC was strongly positively correlated with aCDOM(440) and followed a similar seasonal trend but it demonstrated more variability than either aCDOM or SCDOM with distance through the system. Photobleaching resulting from 7 days exposure to natural solar UV radiation resulted in a marked decrease in allochthonous CDOM absorption (7.04 to 3.36 m-1, 42% decrease) and an even greater decrease in the absorption of autochthonous CDOM (1.34 to 0.312 m-1, 77% decrease). Photodegradation also resulted in an increase in the spectral slope coefficient of dissolved material. Terrestrial subsidies of dissolved organic matter are known to exert a profound influence over the biogeochemistry and metabolism of lakes. The results from this study show that localized inputs of dissolved matter from wetlands can exert a strong influence over the spatial and seasonal dynamics of CDOM in lakes.
Dataset Description (TOC): 1. Figure 2. Seasonal aCDOM(440), SCDOM(350-500) and DOC concentration variation in Lake Balaton between January and December 2014 and seasonal variability of runoff in Balaton region (Hungary), monthly means from 1921 to 2007 (modified from Anda & Varga, 2010).2. Figure 3. SCDOM (350-500) as a function of aCDOM (440) using the seasonal sampling data for (a) basin Kesthely, SCDOM(350-500) = -0.0005·aCDOM(440) + 0.0205, R2=0.7833, p<0.0001 and (b) basin Szigliguet, SCDOM(350-500) = -0.0114·aCDOM(440) + 0.0277, R2=0.9122, p=0.011; basin Szemes, SCDOM(350-500) = -0.0209·aCDOM(440) + 0.0209, R2=0.7932, p=0.0108 and basin Siófok, SCDOM(350-500) = -0.0507·aCDOM(440) + 0.0317, R2=0.9154, p<0.00001. 3. Figure 4. CDOM absorption spectra for all stations (per basin) and Kis-Balaton. Note the different y-axis scale for basins Szemes and Siófok. 4. Figure 5. Spatial aCDOM(440) variation in Lake Balaton per station. b) Spatial SCDOM(350-500) variation in Lake Balaton per station. c) Spatial DOC concentration in Lake Balaton per station. 5. Figure 6. Scatterplots against distance to the main inflow [Km] with loess curve fitted to data. (a) Variation of CDOM absorption coefficient at 440 nm (aCDOM (440)) [m-1], (b) CDOM slope coefficient between 350 and 500 mm (SCDOM (350-500)) [nm-1] variation, (c) DOC concentration [mg/L] variation, (d) specific UV absorptivity at 254nm (SUVA254) [m-1] and e) E2/E3 ratio as a function of distance from the Zala River during the summer 2014 campaign. 6. Figure 7. SCDOM(350-500) as a function of aCDOM(440) spatial variation. a) Kis Balaton, SCDOM (350-500) = 0.019266*aCDOM(440)-0.017362; basin Keszthely, SCDOM (350-500) = 0.019817*aCDOM(440)-0.070820 and basin Szigliget, SCDOM (350-500) = 0.020418*aCDOM(440)-0.070820. b) Basins Szemes, SCDOM(350-500) = -0.01252·aCDOM(440) + 0.02521 and Siofok, SCDOM(350-500) = -0.03330·aCDOM(440) + 0.027900. 7. Figure 8. Scatterplot of aCDOM(440) plotted as a function of DOC concentration (mg/L). Line is a regression curve by least squares fit. 8. Figure 9. Ultraviolet irradiance during the photobleaching experiment. b) Variation of SCDOM (350-500) per day. c) Variation of aCDOM (400) accumulated UV radiation. d) Variation of aCDOM (400) per day. Note that the error bars represent ± standard deviation and exist for every data ponint corresponding with exposed samples in sub-figures b), c) and d), dark samples not included. 9. Figure 10. Changes of Humic-like fluorescence (Fn(355)) and protein-like fluorescence (Fn(280)) for allochthonous CDOM samples with time during photobleaching experiment. Bars = ±Standard Deviation.
Type: dataset
Contract/Grant Title: Development and adaptation of algorithms for the estimation of carbon budget in lakes
Funder(s): Santander Doctoral Travel Award
University of Stirling Impact Studentship
Contract/Grant Number: 2231634
Geographic Location(s): Lake Balaton (Hungary)
Time Period: 01/2013 - 12/2014
Rights: Rights covered by the standard CC-BY 4.0 licence:
Affiliation(s) of Dataset Creator(s): University of Stirling (Biological and Environmental Sciences)
Balaton Limnological Institute
Scottish Universities Environmental Research Centre
Balaton Limnological Institute
University of Vigo

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