Dissolved organic matter fluorescence as a water-flow tracer in the tropical wetland of Pantanal of Nhecolândia, Brazil

Mariot, M.; Dudal, Yves; Furian, Sônia; Sakamoto, Arnaldo Yoso; Vallès, Vincent; Fort, Monique; Barbiéro, Laurent

doi:10.1016/j.scitotenv.2007.08.003

Cited by 42 publications

(41 citation statements)

References 23 publications

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“…The study highlights an important interaction between the saline and freshwater lakes, which has implications for the functioning of the Pantanal ecosystem, involving dissolution and transfer of chemical elements and organic matter (Mariot et al, 2007). It confirms that the co-existence of saline and freshwater lakes is due to a differential hydrological regime, where the freshwater is directed towards the depressions of the saline lakes.…”

Section: Discussionsupporting

confidence: 52%

“…Usual pKa values for natural organic matter are determined by the two most abundant functional groups, 4.7 (carboxyl group) and 10 (phenol group). Consequently, at the observed pH values the dissolved organic compounds are mostly anionic and are also partly contributing to the high electrical conductivity (Mariot et al, 2007). (Goldberg, 2002).…”

Section: Evaporation Concentration and Associated Precipitationsmentioning

confidence: 94%

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Soil morphological control on saline and freshwater lake hydrogeochemistry in the Pantanal of Nhecolândia, Brazil

et al. 2008

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Abstract:Joint pedological, geochemical, hydrological and geophysical investigations were performed to study the coexistence of saline and freshwater lakes in close proximity and similar climatic conditions in the Nhecolândia region, Pantanal wetlands in Brazil. The saline lakes are concentrically surrounded by green sandy loam horizons, which cause differential hydrological regimes.Mg-calcite, K-silicates, and amorphous silica precipitate in the soil cover, whereas Mgsilicates and more soluble Na-carbonates are concentrated in the topsoil along the shore of the saline lake. In saline solutions, some minor elements (As, Se) reach values above the water quality recommendations, whereas others are controlled and incorporated in solid phases (Ba, Sr). Locally, the destruction of the sandy loam horizons generates very acidic soil solution 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64

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Section: Discussionsupporting

confidence: 52%

Section: Evaporation Concentration and Associated Precipitationsmentioning

confidence: 94%

Soil morphological control on saline and freshwater lake hydrogeochemistry in the Pantanal of Nhecolândia, Brazil

et al. 2008

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“…Comparison of DOC-conductivity relationships among saline lakes globally. Regressions from regions other than this study were calculated on data presented in the referenced study (data were estimated averages from Mariot et al 2007 None of these studies consider DOM photodegradation as a contributing factor to CO 2 flux from saline lake surface waters, although our results and those of Waiser and Robarts (2004) clearly demonstrate the importance of photodegradation in saline lake carbon cycles.…”

Section: Discussionmentioning

confidence: 89%

Dissolved organic matter composition and photoreactivity in prairie lakes of the U.S. Great Plains

Osburn¹,

Wigdahl²,

Fritz³

et al. 2011

Limnology & Oceanography

210

105

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Dissolved organic matter (DOM) of 27 prairie saline lake ecosystems was investigated in the Northern and Central Great Plains of the United States using absorbance, fluorescence, lignin concentration, and stable C isotope values. The majority of variation in DOM fluorescence among lakes was due to humic (peak C) and microbially formed (peak M) fluorescent components, which appear to be derived from autochthonous primary production. Strong correlations between peak M and nutrients allow us to model total phosphorus (TP) concentration using peak M fluorescence and chromophoric dissolved organic matter (CDOM) absorption. The rate of primary production (PP) was positively correlated with peak M fluorescence and negatively with lignin concentration. Lignin phenol yields in the DOM were generally smaller than those of most freshwater systems. d 13 C values of dissolved organic carbon (DOC) ranged from 225.0% to 220.1% and were generally enriched relative to typical freshwaters (ca. 227%). Terrestrial DOM is degraded in prairie lakes, spanning a gradient from mixotrophic to eutrophic, as determined by a color-nutrient model. The photodegradation of autochthonous DOM was significant: CO 2 fluxes from these prairie lakes, modeled from peak M fluorescence, ranged from 5 to 228 mmol C m 22 d 21 (median, 37 mmol C m 22 d 21 ) and was similar to community respiration estimated from protein fluorescence (median, 50 mmol C m 22 d 21 ). The combined estimates were about 50% of the global mean total C release previously reported for saline lake ecosystems. The implication of these new results is that the global C release from saline lake ecosystems is likely underestimated.

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“…According to Rezende Filho et al (2012), the gradual and continuous chemical changes from the most diluted to the most concentrated waters allowed to link their origin to the chemistry of the Taquari River freshwater that supply the region. Nhecolândia has relatively closed drainage with little connection to major 20 fluvial systems, and therefore, the organic matter in the lakes depends more on the local cycles than on terrestrial inputs by the annual inundation pulse (Mariot et al, 2007). Semihumid climate patterns, classified as tropical humid with short dry season ("Aw" type in the Köppen classification), are controlled by the seasonal migration of the Intertropical Convergence Zone (ITCZ).…”

Section: Studied Areamentioning

confidence: 99%

“…Furian et al (2013) have shown that the level of salinity of neighboring lakes are independent and that the co-20 existence of both, saline and freshwater lakes occurs as a result of the distribution of the soil cover that induce a differential hydrological regime. Under the influence of cumulative evaporation over the years, the pH of some saline lakes has reached high values, close to or above 10, resulting in an increasing solubility of the organic matter, with dissolved organic carbon (DOC) values up to 750 mg L -1 (Barbiero et al, 2016;Mariot et al, 2007). Martins (2012) noticed that waters of neighboring saline lakes with almost similar chemical composition can have permanent black or green color, resulting from opposite 25 biogeochemical functioning, but the parameters that control such differences are still poorly understood.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical diversity and hot moments of GHG emissions from shallow alkaline lakes in the Pantanal of Nhecolândia, Brazil

Barbiéro

Neto

Braz

et al. 2017

Preprint

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Abstract. Nhecolândia is a vast sub-region of the Pantanal wetland in Brazil with great diversity in surface water chemistry evolving in a sodic alkaline pathway under the influence of evaporation. In this region, more than 15,000 shallow lakes are likely to contribute an enormous quantity of greenhouse gas to the atmosphere, but the diversity of the biogeochemical scenarios and their variability in time and space is a major challenge to estimate the regional contribution. In this study, we compiled measurements of the physico-chemical characteristics of water and sediments, gas fluxes in floating chambers, and 25 sedimentation rates to illustrate this diversity. Although these lakes have a similar chemical composition, the results confirm an opposition between the black-water and green-water alkaline lakes, corresponding to distinct biogeochemical functioning.Black-water lakes are CO 2 and CH 4 sources, with fairly constant emissions throughout the seasons. Annual carbon dioxide and methane emissions approach 790 mmol m -2 y -1 and 73 mmol m -2 y -1 , respectively. By contrast, green-water lakes are CO 2 sinks but significant CH 4 sources with fluxes varying significantly throughout the seasons, depending on the 30 development of the cyanobacterial bloom. The results highlight two hot moments for methane emissions. The first one is suspected after the disappearance of the cyanobacterial bloom, which is accompanied by a drop in pH of the upper part of the sediments. The second one is identified when the O 2 -supersaturation is reached under extreme bloom and sunny weather conditions, which provoke an abrupt O 2 purging of the lakes. Taking into account the seasonal variability, annual methane emissions are around 8,850 mmol m -2 y -1 , i.e., much higher than reported in previous studies for alkaline lakes in

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Dissolved organic matter fluorescence as a water-flow tracer in the tropical wetland of Pantanal of Nhecolândia, Brazil

Cited by 42 publications

References 23 publications

Soil morphological control on saline and freshwater lake hydrogeochemistry in the Pantanal of Nhecolândia, Brazil

Soil morphological control on saline and freshwater lake hydrogeochemistry in the Pantanal of Nhecolândia, Brazil

Dissolved organic matter composition and photoreactivity in prairie lakes of the U.S. Great Plains

Biogeochemical diversity and hot moments of GHG emissions from shallow alkaline lakes in the Pantanal of Nhecolândia, Brazil

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