The chemical mass balance of the amazon plume—II. Copper, nickel, and cadmium (original) (raw)
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Distribution and partition of trace metals in the Amazon basin
Hydrological Processes, 2003
The distribution of trace metals (V, Cr, Mn, Co, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Cs, Ba, U) was investigated in surface waters and associated particulates in the Amazon mainstream (Solimões and Amazon rivers). Dissolved V, Cu, As, Sr, Ba, U correlate with major ions and appear to be predominantly derived from soluble rocks occurring in the Amazon upper basin. These elements appear conservative in waters and are progressively diluted by less-concentrated waters coming from the lowland and shield areas. A monthly time series obtained at the Óbidos gauging station shows that temporal variability of trace element concentrations reflects the source, remobilization and/or biological processes occurring in the channel or in the surrounding floodplain lakes. The trace element concentrations in the particulate matter show a clear relationship with the location of the samples. V, Co, Cr, Mn, Sr, Cs and Ba concentrations are higher in the Solimões and the Rio Negro is enriched in Fe, Al and Zn. In the Rio Solimões, V, Cr, Mn, Co, Ni, Zn, Cs and Pb are almost entirely carried by the river particulate matter; Cu, Rb, Sr, Ba and U are transported mainly by the suspended particles, but a dissolved phase contributes to the transport. In the Rio Negro, the proportion of elements transported by the dissolved phase is higher for the whole set of elements. The implications of these results allow us to compute the fluxes from the Amazon River to the Atlantic Ocean.
A first quantitative estimate of trace metal fluxes from Amazon river and its main tributaries
Journal de Physique IV (Proceedings), 2003
The trace metal (V, Cr, Mn, Co, ell, Zn, As, Rb, Sr, Mo, Cd, Sb, Cs, Ba, U) concentrations and temporal variabilities of the Amazon river and its main tributaries are studied on time series basis in the major tributaries of Amazon river (Negro, Madeira and Solimbes Rivers) and at Obidos station on the Amazon mainsteem which represents 90% of the total discharge of Amazon river to the Ocean. Variations of river chemistry may reflectvariations of the sources. The "Shield" rivers(as the Rio Negro) have typically depleted concentrations in As, Sr, Ba, Cu, and V as compared with Andean rivers. Elements such Mn and As are mainly transported by the flood flows. These elements are known to be concentrated in lateric (ferricrete) soils which represent 80% in the Amazon basin, suggesting that these elements are washed away in solution during the high discharge. Moreover, these elements can be stored in the surrounding floodplain areas (varzea) where deposition/resuspension cycles as well as the exchange rate between floodplain and mainstream channel may control at least partially the temporal variation of redox element concentrations such Mn and As. Implication on these results on the trace element flux from Amazon River to the Atlantic Ocean is discussed.
Amazon estuaryassessment of trace elements in seabed sediments
… of radioanalytical and …, 1997
The interactive processes operating on the continental shelf adjacent to the river mouth control the amount and the characteristics of the Amazon discharge reaching the Atlantic Ocean. In this study, the distribution of trace elemental concentrations, with ...
The chemical mass balance in the Amazon plume I: The nutrients
Deep Sea Research Part A. Oceanographic Research Papers, 1981
In May and June 1976, the Amazon plume was dominated by a diatom bloom centered on the 10x 10-3 isohaline. The bloom was apparently initiated by the increased transparency produced by the rapid settling of the fluvial detrital load. The bloom removes the nitrate and phosphate from the surficial layer. The underlying salt wedge was enriched by remineralisation of planktonic debris. A balance between the dissolved and particulate material shows that the regeneration was essentially complete for carbon and phosphorus; but about 50",, of the nitrogen was unaccounted for, having been solubilised to species other than nitrate and nitrite. Only 20°Jo of the silica removed as diatoms (~ 25% of the river dissolved flux) could be accounted for as salt wedge enrichment. The rest must have been incorporated in the sediment. The composition of the river waters was strongly affected, before entry to the mixing zone, by remineralisation of a large fraction of the fluvial particulate organic material in the broad area of multi-channel flow above the mouth.
Carbon and metal concentrations, size distributions and fluxes in major rivers of the Amazon basin
Hydrological Processes, 2003
The chemical composition of the Amazon River results from the mixing of two water types: black water and white water. On-site fractionation by sequential tangential ultrafiltration (STUF) was used to differentiate transported organic carbon and to determine the distribution and association of major and trace elements with different size fraction of the organic carbon (OC). Several sampling campaigns (1994)(1995)(1996) allow a monthly quantification of particulate (OC P , Me P ), colloidal (OC C , Me C ) and dissolved (OC D , Me D ) organic carbon and metal ions inputs. In white rivers the OC is mainly concentrated in the low molecular weight fraction (OC D < 5000 D) while in black rivers most of the OC is in the heavier molecular weight fractions (OC P and OC C > 5 kDa). For Mg, Ca and K, 50% of the total amount of each element is found in fraction Me D while 15% and 35% are found in fractions Me C and Me P , respectively. Al and Fe are in the particulate fraction at 99% of the total metal concentration for all river samples. This work emphasizes the coagulation processes and the sink for elements in the mixing zone. These physicochemical transformations of the organic matter vary seasonally. The changes happen during the transition periods: before high-level waters and before low-level waters. By way of flux measurement, a seasonal carbon loss was observed. The estimated annual organic carbon flux of the Amazon atÒbidos is 28 ð 10 6 t. At the same time, an average of 9 ð 10 6 t of organic carbon per year is retained in the reach between Manaus andÒbidos, probably via coagulation processes.
Journal of Geophysical Research, 1981
Analyses of precipitation and surface water are used to estimate the fluxes of marine cyclic salts through that part of the Amazon River system draining past Obidos (80% of the basin) at the time of peak discharge in June. Amazon precipitation chemistry can be devided into two principal components: marine and terrestrial. The marine component (determined from analyses of marine rain) consists of Na, K, Mg, Ca, and C1 in approximately sea-salt proportions, with S doubly enriched. The excess sulfur is probably derived from gas phase inputs. The terrestrial component makes an important contribution of K, Ca, S, and N, much of which can be related to biological emissions. The emission of reduced sulfur in the marine and terrestrial environment and nitrogen in the terrestrial environment is responsible for a natural 'acid rain' in the Amazon region with a pH from 4.7 to 5.7. This is about one tenth the acidity of polluted urban rain. The chloride content of lowland rivers, which drain regions lacking significant geologic sources of chloride, shows a systematic decrease in chloride with increasing distance from the ocean. This trend is used to define the cyclic salt background for Amazonian surface waters. Cyclic salts, in general, make only a minor contribution, relative to terrestrial inputs, to the chemistry of Amazon Basin rivers, even those draining intensely weathered terrains. An estimated 17.6%-C1, 6.9%-Na, 1.3%-Mg, 3.6%-S, 0.4%-K, and O.l%-Ca of the dissolved load at Obidos during peak discharge is cyclic. mates are calculations based on reviews of available literature. The examples from small watershed studies were derived from coordinated measurements of atmospheric inputs and river outputs. Atmospheric contributions for several elements are quite large and vary considerably between estimates suggesting that great uncertainty exists in the procedures used. There is no direct way to measure the net flux of atmospherically derived materials being trans
Large scale mercury and trace element measurements in the Amazon basin
Atmospheric Environment, 2000
Large emissions of mercury (Hg) occur in the Amazon Basin as a result of gold mining activities. Mercury and aerosol particles were collected in the Amazon basin, as part of the SCAR-B } Smoke Clouds and Radiation } Brazil experiment in August and September 1995. Three airplanes were used to collect total mercury and aerosol particles. Sampling was performed with the University of Washington Lockheed C131A airplane, as well as in two Brazilian Bandeirante EMB 120 planes. Atmospheric mercury was sampled using two gold traps in series for each sampling line and measured with atomic #uorescence spectrometer (AFS). Aerosols were collected on Te#on and polycarbonate "lters and analyzed by particle-induced X-ray emission (PIXE) for up to 20 elements, and by instrumental neutron activation analysis (INAA) for up to 39 elements. Absorbing aerosols expressed as black carbon (BC), and aerosol gravimetric mass were also determined. Sampling time was 2}4 h. The sampling period was at the peak of the biomass burning season, when most of the Hg is emitted. Concentrations for total Hg in this study were as high as 14.8 ng m\. Factor analysis was performed for the combined (aerosol and Hg) data set and six factors were observed: A soil dust component; a biomass-burning factor (with "ne mode mass concentration, BC, K, Cl, Zn and others); a natural biogenic component (P, K, S, Ca, Mn, Zn); a second soil dust factor (enriched in Si); a sea-salt aerosol component, with NaCl; and a factor related to gold mining activities, with Hg, Pb and other elements. Hg was also clearly associated with the biomass-burning component, in addition to the gold mining activities component. An average of 63% of the Hg concentrations was associated with the gold mining activities. About 31% of the Hg concentration was associated with the biomass-burning component, the soil dust accounted for 4% and the NaCl component for 2.1% of the airborne Hg concentrations. The high association between Hg and biomass burning can be caused by at least three mechanisms: (1) adsorption of gaseous Hg on existing biomass burning particles; (2) direct release of Hg from the vegetation to the atmosphere during forest burning;
2019
Land-use intensification in the "Zona Bragantina" region, an area in the eastern Brazilian Amazon, has accelerated landscape changes from primary forest to a mixture of different land uses: native forest (riparian vegetation), secondary forest, pasture, annual cropland, perennial cropland, bare soil and fallow vegetation, with negative consequences for the stability and equilibrium of river systems. This study examined the temporal and spatial variation of dissolved organic carbon (DOC) and metal concentrations in stream water of the Cumaru (ICU) and São João (ISJ) watersheds from May 2014 to April 2015, to understand the chemical changes in forests and agro-ecosystems during one year. In both watersheds, higher concentrations of dissolved metals (aluminum, sodium, barium, calcium, iron, potassium, magnesium, copper and zinc) and DOC were measured in the rainy season, with considerable variability due to precipitation events. Furthermore, strong spatial variation was observed, with lower conductivity, higher pH, and higher concentrations of DOC and dissolved metals in the downstream reaches, especially for DOC in a small reservoir below a dam in ISJ. Significant human intervention was located in these downstream areas, including nearby agriculture and pasture, and use of stream resources for domestic activity. Sandy soil in these areas likely facilitated leachate processes, mainly in deforested areas, supporting the increased movement of metals from the land to the stream.
Distribution of Metals in the Waters and Sediments of Rivers in Central Amazon Region, Brazil
Journal of the Brazilian Chemical Society, 2019
Seasonal concentrations of total, particulate and dissolved Al, Cu, Cd, Cr, Fe, Pb and Ni were analyzed in surface water and total metals in sediment samples from black and whitewater rivers within the Itacoatiara City, Central Amazon. Metals concentrations in water and sediment samples demonstrated that even though urbanization and agricultural practices are common in this region. Metal concentrations in sediments samples are acceptable regarding the recommended levels for protection of aquatic life. From this work, which is the first trace elements study in the main tributaries from Itacoatiara region, we conclude that metals are present in a particulate form, being easier to be transported to other aquatic bodies. During flooding periods an increase of Al, Fe and total organic compound (TOC) in almost water sampling points was observed.