The distributions of colloidal and dissolved organic carbon, major elements, and trace elements in small tropical catchments

Eyrolle, Frédérique; Benedetti, Marc F.; Bénaïm, J.; Février, Dominique

doi:10.1016/0016-7037(96)00210-4

Cited by 90 publications

(42 citation statements)

References 48 publications

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“…All of these factors are known to be important in controlling the concentration and composition of DOM (Sedell and Dahm, 1990). Nevertheless, the results for the Fly River system are in agreement with studies conducted in several tropical South American catchments (Eyrolle et al, 1996), Benaim and Mounier, 1998) which indicated that the CuCC of filtered waters was dominated by organic ligands residing in the <5,000 MWCO fraction.…”

Section: Size Fractionationsupporting

confidence: 89%

“…The size of the metal complex is important as it potentially affects the reactivity and mobility of metals and will play a major role in determining the nature of adsorptive interactions with solid phases and the extent of copper precipitation during estuarine mixing. Most size distribution information has been obtained using samples first fractionated by ultrafiltration (Buffle et al, 1978;Hoffman et al, 1981;Eyrolle et al, 1996;Mounier et al, 1999). These studies have shown that most complexing ligands are found in the <1,000 to 50,000 molecular weight cut-off (MWCO) range, but the proportion of small ligands (<1,000 MWCO) is highly variable and appears to be determined by processes occurring in individual catchments.…”

Section: Introductionmentioning

confidence: 99%

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Size distribution of copper complexing ligands in tropical freshwaters

Apte

Rowland

Patney

2000

Chemical Speciation & Bioavailability

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Section: Size Fractionationsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Size distribution of copper complexing ligands in tropical freshwaters

Apte

Rowland

Patney

2000

Chemical Speciation & Bioavailability

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“…High transient potassium concentration is a typical pattern in forest soils in which rapid release of potassium from decomposing litter commonly exceeds the capacity of the soil to retain it (Laskowski et al, 1995;Chang et al, 2007). Potassium may also be contained in colloidal sized plant material as was reported by Eyrolle et al (1996).…”

Section: Discussionmentioning

confidence: 81%

The significance and lag-time of deep through flow: an example from a small, ephemeral catchment with contrasting soil types in the Adelaide Hills, South Australia

Bestland

Milgate

Chittleborough

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract. The importance of deep soil-regolith through flow in a small (3.4 km2) ephemeral catchment in the Adelaide Hills of South Australia was investigated by detailed hydrochemical analysis of soil water and stream flow during autumn and early winter rains. In this Mediterranean climate with strong summer moisture deficits, several significant rainfalls are required to generate soil through flow and stream flow [in ephemeral streams]. During autumn 2007, a large (127 mm) drought-breaking rain occurred in April followed by significant May rains; most of this April and May precipitation occurred prior to the initiation of stream flow in late May. These early events, especially the 127 mm April event, had low stable water isotope values compared with later rains during June and July and average winter precipitation. Thus, this large early autumn rain event with low isotopic values (δ18O, δD) provided an excellent natural tracer. During later June and July rainfall events, daily stream and soil water samples were collected and analysed. Results from major and trace elements, water isotopes (δ18O, δD), and dissolved organic carbon analysis clearly demonstrate that a large component of this early April and May rain was stored and later pushed out of deep soil and regolith zones. This pre-event water was identified in the stream as well as identified in deep soil horizons due to its different isotopic signature which contrasted sharply with the June–July event water. Based on this data, the soil-regolith hydrologic system for this catchment has been re-thought. The catchment area consists of about 60% sandy and 40% clayey soils. Regolith flow in the sandy soil system and not the clayey soil system is now thought to dominate the deep subsurface flow in this catchment. The clayey texture contrast soils had rapid response to rain events and saturation excess overland flow. The sandy soils had delayed soil through flow and infiltration excess overland flow. A pulse of macropore through flow was observed in the sandy soils three days after the rainfall event largely ended. The macropore water was a mixture of pre-event and event water, demonstrating the lag-time and mixing of the water masses in the sandy soil system. By contrast, the clayey soil horizons were not dominated by pre-event water, demonstrating the quicker response and shallow through flow of the clayey soil system. Thus, the sandy terrain has a greater vadose zone storage and greater lag time of through flow than the clayey terrain.

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“…Crystallized and amorphous Fe and Al have a tremendous complexation capacity for organic matter and most notably for large, hydrophobic organic molecules that constitute colloidal organic matter (Jonsson 1997). In central Amazonia, organic colloidal matter transports an important part of Fe and Al and other metals in dissolved fractions (Ͻ0.45 m) (Eyrolle et al 1996) and coagulated with mineral particles (Chauvel et al 1996). In the Tapajós River, Fe cdb and Al cdb contents of FPM are related to the C content (Fig.…”

Section: Discussionmentioning

confidence: 99%

Spatio‐temporal geochemistry of mercury in waters of the Tapajós and Amazon rivers, Brazil

Roulet

Lucotte

Canuel

et al. 2001

Limnology & Oceanography

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Spatial and temporal variations of mercury (Hg) concentrations were monitored in the surface waters from the lower portion of the Tapajós River, the Arapiuns River, its principal tributary, and the Amazon River at its confluence with the Tapajós. In the rivers, Hg concentrations in the water column are governed by the concentration of suspended particles. Hg in the filtered water showed very little seasonal variation with low concentrations in the lower Tapajós (Ͻ1.8 ng L Ϫ1), Arapiuns (Ͻ0.8 ng L Ϫ1 ), and Amazon (Ͻ2.8 ng L Ϫ1). Concentrations of fine particulate Hg (0.6-29.7 ng L Ϫ1 ) represent 40%-90% of the total volumetric concentration of Hg. In relation to their oxyhydroxide contents, suspended particles are not richer in Hg than nearby soils where oxyhydroxides control the accumulation of Hg. The study shows that the dominant stock of Hg in the aquatic ecosystems of this region is derived from erosion of natural soils in the catchment rather than from anthropogenic pollution. The input of natural Hg coming from soils into the aquatic ecosystems may have increased over historical levels in the region. This increase of total Hg in aquatic ecosystems could potentially account for high levels of methylmercury recently reported in fish and humans in the lower Tapajós River area, but the link between the different processes that promote high levels of methylmercury exposure for the human community remains to be proved.Numerous recent studies (Bidone et al. 1997; Lebel et al. 1997;Malm et al. 1997) have documented exceedingly elevated levels of mercury in fish of the Tapajós River, one of the principal tributaries of the Amazon River. Exposure to methylmercury (MeHg) through fish consumption by the 1 Present address: IRD-Bolivia, CP 9214, La Paz, Bolivia (roulet@cict.fr). AcknowledgementsThe project would never have seen the light of day without the collaboration of Aldo Queiroz Gomes, coordinator of the Santarém campus and Cristovan Waverly Diniz, rector of the Universidade Federal do Pará (UFPa). We would also like to thank Louise Cournoyer, Gerson da Costa de Oliveira, Jean Lebel, Pierre Pichet, Everaldo Portella, Isabelle Rheault, Sewbert Rodrigues Jati, Gil Serique, Delaine Sampaio da Silva, Persio Scavone de Andrade, Nicolas Soumis, Silmara Sousa de Morales, Carlos-José Sousa Passos, Sophie Tran, and Ronilson Vasconcelos Barbosa for their assistance in the field and the laboratory. The analytical methods used for Hg were developed by Professor P. Pichet for the laboratory of the Chaire de Recherche en Environnement H-Q/CRSNG/UQAM.

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The distributions of colloidal and dissolved organic carbon, major elements, and trace elements in small tropical catchments

Cited by 90 publications

References 48 publications

Size distribution of copper complexing ligands in tropical freshwaters

Size distribution of copper complexing ligands in tropical freshwaters

The significance and lag-time of deep through flow: an example from a small, ephemeral catchment with contrasting soil types in the Adelaide Hills, South Australia

Spatio‐temporal geochemistry of mercury in waters of the Tapajós and Amazon rivers, Brazil

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