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Based on the assumptions that human food is available for dogs and isotope diet-tissue differences are similar in dogs and humans, the 'canine surrogacy approach' (CSA) has been used to infer patterns of ancient populations. The goal of this study was to test the CSA in urban (Brasilia and Piracicaba) and in rural (Ubatuba and Maraa) areas. The hair C and N isotope ratios of modern dogs were compared with those of human fingernails from different regions of Brazil. Our CSA results showed a correlation between dog and human isotopes values: in rural areas δ15N of humans and dogs was not statistically different; contrarily, in urban centres, δ15N of humans was approximately 1 ‰ higher (p

A forensic approach was used to evaluate sediments from Portao Stream, including analysis of metals, carbon (C) and nitrogen (N) stable isotopes, and C:N ratios. Samples collected at various points located along the stream were tested in order to investigate a possible illegal leachate input. The studied stream is heavily impacted by sewage and industrial discharges from two cities along its course. Among the metals analyzed, chromium (Cr) was noticeably the main pollutant, showing the highest levels, above regulatory limits, downstream from some potential sources of effluents enriched with this metal. Isotope analyses revealed a general trend of depletion in the heavier isotope along the stream for C and N. The exception was one point near a hazardous waste landfill, where relatively more enriched δ13C and δ15N values were found. The isotope and metal analysis results indicated that this site was affected by a particular source, demonstrating the combination of these parameters could be used for the disc...

Background: Patterns in tropical forest nitrogen cycling are poorly understood. In particular, the extent to which leguminous trees in these forests fix nitrogen is unclear. Aims: We aimed to determine factors that explain variation in foliar δ15N (δ15NF) for Amazon forest trees, and to evaluate the extent to which putatively N2-fixing Fabaceae acquire nitrogen from the atmosphere. Methods: Upper-canopy δ15NF values were determined for 1255 trees sampled across 65 Amazon forest plots. Along with plot inventory data, differences in δ15NF between nodule-forming Fabaceae and other trees were used to estimate the extent of N2 fixation. Results: δ15NF ranged from −12.1‰ to +9.3‰. Most of this variation was attributable to site-specific conditions, with extractable soil phosphorus and dry-season precipitation having strong influences, suggesting a restricted availability of nitrogen on both young and old soils and/or at low precipitation. Fabaceae constituted fewer than 10% of the sampled trees, and only 36% we...

The concept of global ecosystem services has become a powerful paradigm for understanding the link between ecosystem processes and related human activities, which is expressed by the economic and ecological quantification of the services in regards to sustainable development. The role of tropical forests in the global climate system and the uncertainty of the exact magnitude of this complex interaction has become a major concern to the scientific community. In this paper we review and synthesize the global effects of Amazon deforestation in Brazil, as well as drivers and challenges related to this process. To this end, we provide data on carbon emissions from combined annual maps of clear cutting of primary forests and spatial information on biomass distribution for different vegetation types and secondary vegetation growth, as well as the temporal dynamic related to the deforestation process and its interregional heterogeneity, the social and institutional drivers. In 2009, during the Conference of Parti...

In order to identify the ontogenetic changes in the food items assimilated by the larvae of Plagioscion squamosissimus and Hypophthalmus edentatus, we analyzed the stomach content and the nitrogen isotopic value (δ 15N) from the larvae. Samplings were performed monthly, from October 2002 to March 2003, and October 2003 to March 2004 in the subbasin of the Ivinheima River (Upper Parana River floodplain), Mato Grosso do Sul State, Brazil. The food items assimilated by the larvae of P. squamosissimus changed with respect to the developmental stages. In the preflexion stage, we found a large contribution of phytoplankton, followed by zooplankton. During the flexion and post-flexion stages, we recorded a decrease in phytoplankton contribution, an increase in zooplankton contribution, and the presence of zoobenthos. In H. edentatus, phytoplankton made the greatest contribution, followed by zooplankton. Ontogenetic changes in δ 15N for this species were not detected. For both species, the food item predominantly...

The stable isotope content of samples of precipitation and of the river water throughout the Piracicaba basin in Brazil was measured over a two-year period. The isotope values of precipitation follow a consistent pattern of relatively depleted values of both deuterium and oxygen 18 during the rainy summers and enriched ones during the dry winters, with all values aligned slightly above the Global Meteoric Water Line. The isotopic composition of the river water throughout the basin shows a remarkable spatial coherence and much smaller scatter of data than those of the precipitation. The isotope composition of river water is close to that of the precipitation in the rainy season, however, with a consistent lower d-excess value by 1/1000-2/1000. This is attributed to evaporative water loss in the basin, in part an expression of the recycling of water due to the anthropogenic activity in the region. The more divergent values are recorded during high-water stages in the rivers. In many cases, the floods during the beginning of the rainy season are characterized by an enrichment of the heavy isotopes and lower d-excess values when compared to the precipitation, with the opposite situation later in the rainy season. This is interpreted as resulting from the watershed/riverflow interaction pattern, and it thus suggests that the isotope composition can monitor the hydrologic situation in the basin and its changes.

Remote sensing data, a GIS, and the Universal Soil Loss Equation model (USLE) are used to develop maps of erosion risk in the Piracicaba River basin, southeastern Brazil. The mapping program was designed to determine soil erosion losses under various land uses and the extent to which land use changes affected erosion risk during 1978–1993. To evaluate the latter, the USLE model was used to simulate erosion risk during January, the highest-precipitation month, in 1978 and 1993. This made it possible to identify the areas of highest erosion risk and to develop soil/water conservation countermeasures.

Measurements of the stable carbon isotopic composition of methane (CH4) trapped in bubbles in the sediments and CH4 emitted to the atmosphere from wetland areas of the Amazon River floodplain are r...

(1998). The economic value of the Amazonian flooded forest from a fisheries perspective. SIL Proceedings, 1922-2010: Vol. 26, No. 5, pp. 2177-2179.