Sedimentation rates and metals in sediments from the reservoir Rio Grande - São Paulo/Brazil

Warwick, Peter; Moreira, Silvana; Fávaro, D. I. T.; Campagnoli, Fernando; Mazzilli, B. P.

doi:10.1039/9781847550781-00383

Cited by 2 publications

(2 citation statements)

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“…About 5 g dry material from each sample was dissolved with HNO 3 and HF. The 210 Pb and 226 Ra contents were separated by the method described in Moreira's studies [7]. The samples were placed in a 2 L beaker and the volume was made up to 1 L with water.…”

Section: Methodsmentioning

confidence: 99%

Sedimentation Rate and 210Pb Sediment Dating at Apipucos Reservoir, Recife, Brazil

et al. 2012

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Abstract:The Apipucos Reservoir is located in Pernambuco-Brazil. Several districts of the metropolitan area use this reservoir to dispose of rubbish, waste and sewage. Dating sediments uses the 210 Pb from the atmosphere. 210Pb is a daughter of the 222 Rn, which emanates from the soil but is different from that contained in the sediment, which is in balance with the 226 Ra. The chosen model for dating sediments depends on certain conditions: in environments where the amount of sediment can vary, the Constant Rate of Supply (CRS) model is adopted. In environments where the sediments can be considered to be constant, a Constant Initial Concentration (CIC) model is applied. A 70 cm long and 5 cm internal-diameter wide core was used for sediment sampling. Samples were dried at 105 C, and about 5 g dry material was dissolved with acids. The 210 Pb and 226 Ra content was determined by their radioactive descendants' concentrations. For the second sampling point, both models could be used. The results showed an increase in sedimentation rate over the last 50-60 years. We could conclude that the top sediment interval had been there 30 years ago. We could decide that the CRS was the best applicable model.

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Section: Methodsmentioning

confidence: 99%

Sedimentation Rate and 210Pb Sediment Dating at Apipucos Reservoir, Recife, Brazil

et al. 2012

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“…The procedure consists of an initial precipitation of Ra and Pb with 3M-H2SO4, dissolution in nitrile tri-acetic acid at basic pH, precipitation of Ba ( 226 Ra)SO4 with ammonium sulfate, and 210 PbCrO4 by sodium chromate. The 226 Ra concentration was assessed measuring the alpha counting on the precipitate Ba( 226 Ra)SO4, whereas the 210 Pb concentration was assessed through its disintegration product 210 Bi, measured by beta counting on the precipitate 210 PbCrO4(Moreira et al, 2003). Unsupported 210 Pb (denoted 210 PbExc) were obtained from the 226 Ra and total 210 Pb activities.…”

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Biogeochemical diversity, O2-supersaturation and hot moments of GHG emissions from shallow alkaline lakes in the Pantanal of Nhecolândia, Brazil

Barbiéro

Neto

Braz

et al. 2018

Science of The Total Environment

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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, >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. From 4 selected alkaline lakes, we compiled measurements of the physico-chemical characteristics of water and sediments, gas fluxes in floating chambers, and sedimentation rates to illustrate this diversity. Although these lakes have a similar chemical composition, the results confirm a difference between the black-water and green-water alkaline lakes, corresponding to distinct biogeochemical functioning. This difference does not appear to affect lake sedimentation rates, but is reflected in gas emissions. Black-water lakes are CO and CH sources, with fairly constant emissions throughout the seasons. Annual carbon dioxide and methane emissions approach 0.86molmy and 0.07molmy, respectively, and no clear trend towards NO capture or emission was observed. By contrast, green-water lakes are CO and NO sinks but important CH sources with fluxes varying significantly throughout the seasons, depending on the magnitude of the phytoplankton bloom. The results highlight important daily and seasonal variations in gas fluxes, and in particular a hot moments for methane emissions, when the O-supersaturation is reached during the afternoon under extreme bloom and sunny weather conditions, provoking an abrupt O purging of the lakes. Taking into account the seasonal variability, annual methane emissions are around 10.2molmy, i.e., much higher than reported in previous studies for alkaline lakes in Nhecolândia. Carbon dioxide and nitrous oxide consumption is estimated about 1.9molmy and 0.73mmolmy, respectively. However, these balances must be better constrained with systematic and targeted measurements throughout the seasons.

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Sedimentation rates and metals in sediments from the reservoir Rio Grande - São Paulo/Brazil

Cited by 2 publications

References 1 publication

Sedimentation Rate and 210Pb Sediment Dating at Apipucos Reservoir, Recife, Brazil

Sedimentation Rate and 210Pb Sediment Dating at Apipucos Reservoir, Recife, Brazil

Biogeochemical diversity, O2-supersaturation and hot moments of GHG emissions from shallow alkaline lakes in the Pantanal of Nhecolândia, Brazil

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