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The influences of biomass burning emissions in the composition of aerosol have been studied during 1 year around the city of Piracicaba (Southeastern Brazil). Inhalable particles, separated in PM2.5 and coarse particulate mode (CPM, with size in the range (2.5

The oxygen isotope ratio (6180, SMOW) of atmospheric CO2 is a powerful indicator of large-scale CO2 exchange on land. Oxygen isotopic exchange between CO2 and water in leaves and soils controls the 8180 of atmospheric CO2. Currently there is little empirical information on the spatial and temporal variation in the s'80 of leaf and stem water in tropical ecosystems. We measured the seasonal dynamics of 6880 in atmospheric CO2 and water in different ecosystem compartments in both primary forest and pasture ecosystems in three different regions of the Amazonian Basin of Brazil (Ji-Parand, Manaus, and Santarem). Within regions, the source (stem) water 8180 values for primary forests and pastures were similar; neither vegetation type exhibited distinct wet-dry season patterns. Daytime leaf water isotope ratios were strongly correlated with predictions of the Craig- Gordon model. The s880 value of leaf water was positively correlated with leaf height above ground because of associated variation in vapor pressure deficit and the 8180 of atmospheric water vapor within forest canopies. Consistent with these observations, the s'1O value of leaf cellulose was positively correlated with forest height. Leaf water from pasture grasses was more 180 enriched than leaf water from forest vegetation. There was a tendency for daytime leaf water to be more enriched in 180 during the dry season, reflecting generally lower humidity conditions during the dry season. Nighttime measurements of the oxygen isotope ratio of ecosystem respired CO2 in both forest and pasture vegetation were not consistent with values expected for CO2 in equilibrium with stem (soil) water, despite nighttime vapor pressure deficits close to zero. Apparently, the 6'1O of leaf water lagged and did not attain isotopic equilibrium at night. Thus, the deviation of nighttime 8180 values of ecosystem respiration from that expected from a CO2 efflux in equilibrium with soil (stem) water increased as 6180 values of ecosystem respiration became 180 enriched. Dis- crimination against CO2 containing 180 (AC'8OO) during photosynthesis was calculated based on measured leaf water 6180 values. Forests had consistently higher modeled AC'800 values than pastures. The daytime isotope effects we calculate for photosynthesis and respiration were consistent with previous model predictions of a strong depletion of 180 in atmospheric CO2 over the Amazon Basin of Brazil.

We measured the 15N natural abundance values of 320 individuals belonging to 45 different plant species of the Brazilian cerrado. We also determined δ15N of soil nitrogen as a function of soil depth. Our purpose was to test the hypothesis that N-limited cerrado would have a large range of plant δ15N values, similar to patterns seen in northern high-latitude ecosystems. Foliar δ15N values did demonstrate the large range found in some other N-limited ecosystems, varying from −5‰ to +7.9‰. Significant variability within individual species was also seen across cerrado community types. Several factors contributed to this variability, including the presence of N-fixing legumes, associations with mycorrhizal fungi, δ15N variability of soil organic matter with depth, fire events, and the seasonality of N-immobilization and mineralization processes in cerrado soils.

We investigated the forms and composition of dissolved and particulate organic matter in rivers of the Ji-Parana Basin, which is situated at the southern limit of the Amazon lowlands and has experienced extensive deforestation in the last three decades (∼35 000 km2). Our objective was to investigate how extensive land-use changes, from forest to cattle pasture, have affected river biogeochemistry. We measured a series of chemical, biochemical, and isotopic tracers in three size classes of organic matter within five sites along Ji-Parana River and eight more sites in six tributaries. The results were compared with C4 leaf and pasture soils end members in order to test for a pasture-derived signal in the riverine organic matter. The coarse size fraction was least degraded and derived primarily from fresh leaves in lowland forests. The fine fraction was mostly associated with a mineral soil phase, but its ultimate source appeared to be leaves from forests; this fraction was the most enriched in nitrogen. The ultrafiltered dissolved organic matter (UDOM) appeared to have the same source as the coarse fraction, but it was the most extensively degraded of the three fractions. In contrast to Amazon white-water rivers, rivers of the Ji-Parana Basin had lower concentrations of suspended solids with a higher carbon and nitrogen content in the three size fractions. However, principal component analyses showed a correlation between areas covered with pasture and the δ13C values of the three size fractions. The highest δ13C values were observed in the ultrafiltered dissolved organic matter of the Rolim-de-Moura and Jaru rivers, which have the highest areas covered with pasture. The lower the order of the streams and the higher the pasture area, the greater is the possibility that the C4-derived organic matter signal will be detected first in the faster-cycling fraction (UDOM). The large change in land use in the Ji-Parana Basin, replacement of primary forests by C4 pastures for cattle feeding, that has taken place in the last 30–40 yr, has already changed the characteristics of the composition of the riverine organic matter.

This study documents regional patterns in stream nitrogen and phosphorus concentrations in the Brazilian state of Rondonia in the southwestern Amazon basin, and interprets the patterns as functions of watershed soil properties, deforestation extent, and urban population density. The survey includes 77 different locations sampled in the dry and wet seasons, with a watershed size range from 1.8 to 33,000 km2 over a total area of approximately 140,000 km2. A sequential regression technique is used to separate the effects of natural watersheds properties and anthropogenic disturbance on nutrients and chloride. Natural variation in soil texture explains most of the variance in stream nitrate concentrations, while deforestation extent and urban population density explain most of the variance in stream chloride (Cl) and total dissolved nitrogen (TDN) concentrations. Stream TDN, total dissolved phosphorus (TDP), particulate phosphorus (PP) and Cl concentrations all increase non-linearly with deforestation extent in the dry season after controlling for natural variability due to soil type. Stream nutrient and Cl disturbances are observed only in watersheds more than 66–75% deforested (watershed area range 2–300 km2), suggesting stream nutrient concentrations are resistant to perturbation from vegetation conversion below a 66–75% threshold. In heavily deforested watersheds, stream Cl shows the largest changes in concentration (12 ± 6 times forested background), followed by TDP (2.3 ± 1.5), PP (1.9 ± 0.8) and TDN (1.7 ± 0.5). Wet season signals in Cl and TDP are diluted relative to the dry season, and no land use signal is observed in wet season TDN, PN, or PP. Stream TDN and TDP concentrations in non-urban watersheds both correlate with stream Cl, suggesting that sources other than vegetation and soil organic matter contribute to enhanced nutrient concentrations. Small, urbanized watersheds (5–20 km2) have up to 40 times the chloride and 10 times the TDN concentrations of forested catchments in the dry season. Several large watersheds (∼1000–3000 km2) with urban populations show higher Cl, TDN and TDP levels than any small pasture watershed, suggesting that human impacts on nutrient concentrations in large river systems may be dominated by urban areas. Anthropogenic disturbance of dry-season stream Cl and TDN is detectable in large streams draining deforested and urbanized watersheds up to 33,000 km2. We conclude that regional deforestation and urbanization result in changes in stream Cl, N and P concentrations at wide range of scales, from small pasture streams to large river systems.

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.

The levels of Cd, Pb, and Hg were determined in bed sediments and suspended particulate material collected in six Brazilian watersheds (Alto Paranapanema, Peixe, Aguapei, Sao Josh dos Dourados, Mogi-Gaucu, and Piracicaba) in the State of Sao Paulo (Southeast, Brazil), bimonthly from January to December, 2001. The levels of Cd and Pb in total and exchangeable fraction of the sediment were determined in the fraction lower than 63 μm by GFAAS. Cd and Pb in suspended particulate material were determined in the fraction lower than 0.45 pm by GFAAS. The levels of Hg were determined by AFS. The levels of metals did not show temporal variability. Pb concentrations were low in all basins. Exchangeable Pb did not represent a significant fraction of the sediment. Cd concentrations were higher in the Piracicaba River basin, as a result from anthropogenic activities in the basin, such as industrial and domestic effluents damped in the river. Exchangeable Cd was up to 60% of the total Cd in the sediments. Hg concentrations were higher in the Peixe basin. All metals analyzed did not show high values, but the sources of Cd to the Piracicaba River and Hg to the Peixe River have to be evaluated.

High levels of wet N and acidic deposition were measured in southeast Brazil. In this study we addressed the sensitivity of water bodies and soils to acidification and N deposition in the Piracicaba River basin (12,400 km 2 ). Average acid neutralization capacity (ANC) at 23 river sampling sites varied from 350 to 1800 μeq l −1 . Therefore, rivers and streams in the Piracicaba basin are well buffered, if the lower limit of 200 μeq l −1 is assumed as an indication of poorly buffered waters. ANC is increased by untreated wastewaters discarded into rivers and streams of the region. Average NO 3 concentrations varied from 20 to 70 μeq l −1 . At the most polluted river sites, NO 3 concentration is not highest, however, probably due to NO 3 reduction and denitrification. Most of the nitrogen in streams is also provided by wastewaters and not by wet deposition. The majority of the soils in the basin, however, are acidic with a low base cation content and high aluminum concentration. Therefore, soils in this basin are poorly buffered and, in areas of forest over sandy soils, acidification may be a problem.

Anthropogenic N inputs and riverine export were determined for a meso-scale river basin in one of the most developed and economically important regions of South America. The Piracicaba River basin is located in southeastern Brazil and drains into a tributary of the Parana River. The basin supports over 3 million people (about 2% of the population of Brazil) with intensive agricultural and industrial activities. During two years from 1995 to 1997, biweekly samples were collected at 10 stations along the Piracicaba River and its tributaries for analyses of dissolved and particulate N. The average annual flux of dissolved inorganic N and total N increased by a factor of 15 and 20 times, respectively, from the headwaters to the lower reaches of the main channel, whereas discharge increased by only 7 times. On a per area basis, the export of TN varied according to land use and was significantly correlated to the net input of anthropogenic N. Among 10 sub-catchments composing the basin, areas mostly covered by pasture and forest had the lowest export, whereas more agricultural and urban areas had higher ex- port. The amount of N exported from each sub-catchment varied widely, but inputs were consistently higher than fluvial outputs. Losses and retention of N occurred throughout the basin but were especially high in the sub-catchment with a main-stem reservoir, suggesting that aquatic processing plays an im- portant role in controlling riverine N export. Total net anthropogenic input to the Piracicaba River basin was 4,500 (± 900) kg N km �2 yr �1 of which about 40% was exported via fluvial outputs.

We analysed carbon, nitrogen and δ13C values in sediment sampled in the Amazon floodplains. The surface sediment samples were collected along inland transects divided according to their vegetation cover: (a) forest, where the dominant vegetation was inundation forests; (b) grass, where the dominant vegetation was grasses, mainly from Echnochloa polystachya; (c) mixed, where the vegetation changed from grasses near the river bank to forest inland. The average sediment carbon and nitrogen concentrations were significantly higher in forest samples (C = 0·99%, N = 0·12%) than in grass samples (C = 0·84%, N = 0·10%). The average sediment δ13C was significantly heavier in grass (−26·7‰ ) than in forest samples (−28·6‰ ), reflecting the isotopically heavier C4 grasses carbon. In the forest and mixed transects inland, increases in the carbon and nitrogen concentrations were observed. At approximately 50 to 60 m from the riverbank, the concentration of carbon and nitrogen became similar to the river particulate organic carbon (POC) concentration, which is the primary floodplain sediment source. We hypothesized that this trend is caused by the deposition of carbon- and nitrogen-depleted sand-size particles in the first few metres of the floodplain, whereas the more enriched silt–clay particles are preferentially deposited far inland. In contrast to inland trends, no significant downriver trend was observed in the carbon and nitrogen concentrations. However, a downriver δ13C increase was observed for sediment in grass-covered areas. Based on δ13C values in different varzea environments, we estimated the relative contribution of riverine POC and vegetation material present in the varzea sediments under different vegetation covers. For forest sediment samples we estimated that 60% of the carbon was derived from the riverine POC and the forests provided the remaining 40%. For open areas covered with grasses we estimated that only 10% was derived from these plants, and 90% was derived from riverine POC. Copyright © 2003 John Wiley & Sons, Ltd.

A composição isotópica do carbono (delta13C) foi utilizada na determinação da origem botânica (C3 x C4) de amostras de café, vinho, cerveja e vodka, de diferentes marcas e procedências, comercializadas no Brasil. Dentre as marcas de café analisadas, apenas uma apresentou um elevado percentual de plantas C4 em sua composição, evidenciado pelo valor de delta13C (-16,2‰). Os valores de delta13C das amostras de vinhos brasileiros, variaram entre -25,1 e -17,1‰, indicando a presença de carbono de origem C4 nas amostras que tiveram os maiores valores de delta13C. Duas marcas de vinhos importados, por sua vez, apresentaram delta13C característico de planta C3 (-27,1 e -26,3‰). Os valores de delta13C das vodkas importadas variaram entre -26,4 e -23,9‰, e as brasileiras entre -12,8 e -11,8‰, excetuando-se uma marca que apresentou valor -23,1‰. As marcas de cervejas importadas, em sua maioria, apresentaram valores mais negativos (-27,3 a -20,7‰) que as nacionais (-25,9 a -18,4‰). Estes resultados evidenciam a eficiência desta metodologia na determinação da origem do C e percentual de mistura destas bebidas. We used the carbon isotopic composition (delta13C) to determine the botanical origin (whether C3 or C4) of coffee, wine, beer and vodka samples from different brands and origins commercialized in Brazil. Only one coffee sample showed a delta13C typical of a mixture with C4 plants (delta13C -16.2‰). The Brazilian wine samples varied from delta13C -25.1 to -18.6‰, indicating the presence of carbon from C4 plants in samples with greater values, while the imported wine showed delta13C characteristic of C3 plants (-27.1 and -26.3‰). Imported vodka also showed delta13C typical of C3 plants (-26.4 and -23.9‰), while Brazilian counterparts were typically made from C4 plants (-12.8 to -11.8‰), except for one sample (23,1‰). Most of the imported beers showed more negative d13C (-27.3 to -20.7‰) than did the Brazilian beers (-25.9 to -18.4‰). These results demonstrate the method's efficiency for tracing the carbon origin and determining the extent of blending in beverages.

Aim To determine the relationship between stable carbon isotope ratios in surface soils and the present vegetation in Amazonian savannas. Location Areas in and around savannas in the Brazilian Amazonian States of Amazonas, Para, Amapa, Roraima, Mato Grosso and Maranhao. Methods δ13C ratios were measured from surface (0–5 cm depth) soils in fifty-two plots in savanna plots with different covers of trees, shrubs, and grasses, and in ten adjacent areas covered by forest. Results Soil δ13C ratios varied widely (–24.9 to –15.2‰) among and within savannas, but were distinguishable from δ13C ratios under forest (–30.3 to –27.3‰). One site close to forest with 38% tree cover, 44% shrub cover and 45% grass cover was distinguishable from both forest and savanna on Landsat TM5 images, and had a δ13C ratio of –26.7‰. Tree density (TD), basal area (BA) and cover differed strongly between savanna and forest areas. However, most savanna areas had soil organic matter with δ13C ratios closer to those of forest trees than C4 grasses. Main conclusions In Amazonia, soil δ13C values >–25‰ can be unequivocally attributed to savannas irrespective of depth. However, there is no precise relationship between tree or grass cover in savannas and surface-soil δ13C values. This is partly because shrubs, as well as trees and grasses, contribute significantly to soil organic matter δ13C ratios, and partly because there is a stronger negative relationship between area of bare ground and cover of C4 grasses than between area of bare ground and cover of trees or shrubs. This means that the ratio of C3 to C4 plants tends to increase with a decrease in total cover. Areas with large amounts of open ground, may have a small proportion of grass cover relative to tree and shrub cover. Although we did not encounter any such places in this study, very harsh conditions could lead to desert-like formations with little grass cover and soil organic-matter δ13C ratios similar to forest areas.

The carbon and nitrogen isotopic compositions of aerosol particles collected in the Piracicaba region, where C4 plants like sugarcane and pasture dominate the land cover, were measured. For comparison, aerosol particles were also analyzed from the Santarem region, Amazon basin, where the main land cover is primary forest. The average δ13C value of samples collected in Piracicaba was equal to −20.9±0.8‰. The average δ13C of samples collected in Santarem was almost 5‰ smaller than in Piracicaba (−25.8±0.5‰). This difference between the two sites was attributed to the presence of C4 material in Piracicaba aerosol particles. On the other hand, there was no statistical difference between the average δ15N values observed in Piracicaba (10.6±2.8‰) and Santarem (11.5±2.1‰). The δ13C and δ15N values of aerosol particles collected in Santarem were higher than vegetation tissues and soil organic matter, which are the potential sources of organic matter to aerosol particles.

Scaling and partitioning are frequently two difficult challenges facing ecology today. With regard to ecosystem carbon balance studies, ecologists and atmospheric scientists are often interested in asking how fluxes of carbon dioxide scale across the landscape, region and continent. Yet at the same time, physiological ecologists and ecosystem ecologists are interested in dissecting the net ecosystem CO2 exchange between the biosphere and the atmosphere to achieve a better understanding of the balance between photosynthesis and respiration within a forest. In both of these multiple-scale ecological questions, stable isotope analyses of carbon dioxide can play a central role in influencing our understanding of the extent to which terrestrial ecosystems are carbon sinks. In this synthesis, we review the theory and present field evidence to address isotopic scaling of CO2 fluxes. We first show that the 13C isotopic signal which ecosystems impart to the atmosphere does not remain constant over time at either temporal or spatial scales. The relative balances of different biological activities and plant responses to stress result in dynamic changes in the 13C isotopic exchange between the biosphere and atmosphere, with both seasonal and stand-age factors playing major roles influencing the 13C biosphere-atmosphere exchange. We then examine how stable isotopes are used to partition net ecosystem exchange fluxes in order to calculate shifts in the balance of photosynthesis and respiration. Lastly, we explore how fundamental differences in the 18O isotopic gas exchange of forest and grassland ecosystems can be used to further partition terrestrial fluxes.

We investigated the variation of stable (δ13C) soil carbon isotopes in relation to depth in seven of the most important savanna areas to adjacent contiguous forests in the Amazon region. The δ13C of bulk organic matter in all profiles from forested sites increased with soil depth. In forest profiles from Amapa, Alter do Chao, and Roraima, the enrichment was less than 3.5‰ between deeper soil and surface layers, suggesting that C3 plants have remained the dominant vegetation cover. On the other hand, in forest soil profiles from Humaita and Carolina sites, the δ13C enrichment was greater than 3.5‰, indicating the influence of past C4 vegetation or a mixture of C3/C4 vegetation (woody savanna). The surface δ13C values in the savanna profiles were 5–13‰ greater than the comparable forest profiles, indicating the influence of C4 vegetation. Two kinds of isotopic distribution were observed in deeper layers. The savanna profiles at Alter do Chao, Chapada dos Parecis, and Redencao had relatively constan...

– Aquatic macrophytes form the most productive habitat of the Amazon floodplain and account for more than 60% of the net primary production of the ecosystem. Aquatic grasses are the dominant macrophytes and the main feeding ground of Amazonian larval fish. The present study used stable isotopes of nitrogen and carbon to measure the contribution of aquatic grasses to the production of eight larval fish, and describes the structure of the trophic chain. The carnivore larvae were at the third trophic level, and the detritivores were at the second and third trophic levels. The contribution of aquatic grasses to larval fish production was variable. It could reach a mean value of 25% for three species, but its contribution probably did not exceed 12% in the other five species. Resumen 1. Las macrofitas acuaticas representan el habitat mas productivo de la foresta inundada del Amazonas, equivalente a mas del 60% de la produccion primaria en la red del ecosistema. Hierbas acuaticas son las macrofitas dominates y la principal fuente de alimentacion para las larvas de peces de la Amazonia. 2. Nuestro estudio utiliza isotopos estables de nitrogeno y carbono para medir la contribucion de las gramineas acuaticas en el desarollo larvario de ocho especies de peces y describe la estructura de la cadena trofica. 3. Las larvas carnivoras estaban en el tercer nivel trofico, mientras que las detritivoras se localizaran en el segundo y tercer nivel trofico. 4. La contribucion de las gramineas acuaticas en la produccion larvario fue variable. En tres especies la media alcanzo valores del 25%, pero su contribucion, probablemente, no excede el 12% en las otras cinco especies.

N limitation to primary production and other ecosystem processes is widespread. To understand the causes and distribution of N limitation, we must understand the controls of biological N fixation. The physiology of this process is reasonably well characterized, but our understanding of ecological controls is sparse, except in a few cultivated ecosystems. We review information on the ecological controls of N fixation in free-living cyanobacteria, vascular plant symbioses, and heterotrophic bacteria, with a view toward developing improved conceptual and simulation models of ecological controls of biological N fixation.

Soy occupies the largest area of agricultural land in Brazil, spreading from southern states to the Amazon region. Soy is also the most important agricultural commodity among Brazilian exports affecting food security and land use nationally and internationally. Here we pose the question of whether soy expansion affects only economic growth or whether it also boosts socioeconomic development, fostering education and health improvements in Brazilian municipalities where it is planted. To achieve this objective, we divided more than 5000 municipalities into two groups: those with >300 ha of soy (soy municipalities) and those with

Trophic connections among habitats may be central to food-web dynamics in lakes. Lacustrine zooplankton can rely on basal carbon (C) sources from different origins and plays an important link between these and organisms in higher trophic levels. We investigated the basal C sources supporting the planktonic food web and the trophic relationships among zooplankton size fractions in a tropical lake (Carioca) in Brazil. To do so, we measured the C and nitrogen (N) stable-isotope ratios in basal C sources originated in terrestrial, littoral, and pelagic habitats and in zooplankton size fractions, and data were analysed through Bayesian mixing models. Mesozooplankton showed seasonal variation in resource use, specifically a smaller dependence on algae in the wet than in the dry season. In the wet season, mesozooplankton relied more on the detritivore food chain eating mostly microzooplankton (mode: 95.1%), which in turn consumed mostly terrestrial C in this season (mode: 74.7%). Zooplankton size fractions also occupied different relative trophic positions between seasons. These variations seem to follow the seasonal dynamics of in-lake primary production and of terrestrial C inputs. Also, all size fractions of zooplankton, and particularly Chaoboridae larvae, showed low C staple-isotope values, suggesting the consumption of a missing C source.

Latin America encompasses a dizzying array of ecosystems and socioeconomic models, and the region will be highly vulnerable to the projected impacts of climate change in the next century. At the same time, Latin America can significantly contribute to the mitigation of greenhouse gases (GHG) emissions within a sustainable development framework. Land use conversion with associated biomass burning, agriculture with N fertilizers and animal waste are the main anthropogenic sources of nitrous oxide (N2O) emissions in the region, and have increased markedly in the last decades. Effective sustainable managementforthe mitigation of N2O emissions requires the proper evaluation of all sources, many of which are still roughly estimated or unknown, testing alternatives to reduce primary sources, and technological innovation for higher resource-use efficiency within the farm. Current barriers might be overcome through policies that support sustainable practices thatreduce negative environmental impacts and simultaneously maintaining ecosystem function and services. Fil: Bustamante, Mercedes M. C.. Universidade de Brasilia. Departamento de Ecologia; Brasil Fil: Martinelli, Luiz A.. Universidade de Sao Pablo; Brasil Fil: Ometto, Jean P. H. B.. Instituto Nacional de Pesquisas Espaciais. Centro de Ciência do Sistema Terrestre; Brasil Fil: Carmo, Janaina Braga do. Universidade Federal do Sao Carlos; Brasil Fil: Jaramillo, Víctor. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; México Fil: Gavito, Mayra E.. Universidad Nacional Autónoma de México. Centro de Investigaciones en Ecosistemas; México Fil: Araujo, Patricia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Austin, Amy Theresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Pérez, Tibisay. Instituto Venezolano de Investigaciones Cientificas; Venezuela Fil: Marquina, Sorena. Instituto Venezolano de Investigaciones Cientificas; Venezuela

Objetivo: Estudar a automedicação para dor entre estudantes de cursos de medicina e enfermagem da PUCSP em comparação com estudantes das outras áreas de conhecimento. Material e métodos: Esses dados foram obtidos em dois grupos: A - estudantes da área da saúde e B - estudantes da área de ciências humanas e exatas. Utilizou-se um questionário elaborado pelos autores. A análise estatística usou o teste do qui-quadrado e de Fischer. Resultados: Na área de saúde há um predomínio do gênero feminino, e nas outras áreas um predomínio masculino. Na área de saúde a maior parte dos estudantes cursa medicina, e nas outras áreas engenharia. Observa-se um alto índice de automedicação em ambos os grupos, constatando-se que os participantes do grupo da área de saúde usam significativamente mais opioides e anti-inflamatórios que os demais estudados. Conclusão: A frequência do uso de medicamentos para dor é maior no grupo de estudantes da área de saúde, e a automedicação é praticada igualmente entre estudantes da área de saúde e das demais áreas. Objective: To study the self-medication for pain among students of medicine and nursing of the PUCSP compared with students from other knowledge areas. Material and methods: Data were obtained in two groups: A - students from the health knowledge area, and B - students of law and engineering. It was used a questionnaire developed by the authors. Statistical analysis used the Chi-square test and the Fischer. Results: In relation to gender, there is a predominance of women in the health group and a male majority in other one. In the health group there was a greater number of medical students, and in the control group of engineering. It is observed a high degree of selftreatment in both groups. It appears that participants in the health group have used more anti-inflammatory drugs and opioid than the others subjects studied. Conclusion: The frequency of medication for pain is higher in the group of health students, and self-medication is equally practiced among students of health and other areas.

The application of stable isotopes analysis in wildlife studies has increased in recent decades due to the wide range of information that can be obtained with this methodology. This chapter aims to present the basic principles of the stable isotopes analysis and their potential applications in wildlife studies. The main topics presented are diet reconstruction, trophic level, animal movements, tissue turnover rates, and ecotoxicology.

The influences of different kinds of anthropogenic activities on rainwater chemistry in a tropical area were studied during one uninterrupted year at Piracicaba River Basin (Southeast Brazil). A total of 272 rainwater samples collected continuously from August 1997 to July 1998 at four different sites were analyzed for F − , CH 3 COO − , HCOO − , MSA, Cl − , NO 2 − , Br − , NO 3 − , SO 4 2− , C 2 O 4 2− , PO 4 3− , Na + , NH 4 + , K + , Mg 2+ , Ca 2+ , DOC (dissolved organic carbon), DIC (dissolved inorganic carbon), pH and conductivity. The most abundant ion was H + and rain acidity was significant at all sampling sites (average pH of 4.4–4.5). The sources of this free acidity differ among sites and appear to be correlated to the different land-uses. The composition of rainwater appeared to be controlled mostly by three sources: soil dust, sugar cane burning and industrial emissions.

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.

We studied the effects of lizard size, and availability of C3 and C4 plants, on stable carbon-isotope (δ13C) ratios of lizards in an Amazonian savanna. Availability of C3 and C4 plants was estimated from 500-point quadrats in each of 38 plots of 3.75 ha. Ratios of δ13C in muscle tissue were used to estimate the contributions of C3- and C4-based food chains to the diets of four species of lizards: Cnemidophorus lemniscatus, Kentropyx striata, Ameiva ameiva, and Anolis auratus. The relative contributions of C3 and C4 plants to the diets of the lizards were affected by the extent of shrub cover in C. lemniscatus, A. auratus, and possibly in K. striata. However, there was a strong effect of lizard size among and within lizard species. These results are at variance with a previous evaluation of diet overlap among size classes of these species that was based on overlap in prey taxonomic categories. This indicates that species and/or size classes of predators on arthropods may obtain their energy from food chain...

SUMMARY 1. Several studies have shown that land use has a strong influence on river chemistry and its biotic components. Most of these studies focused on nitrogen in temperate American and European catchments. Much less is known about the relationship between stream conditions and land use in tropical areas of developing countries. 2. Besides climate, there are three important differences between attributes of temperate and tropical catchments: non-point sources are the dominant contributor of pollution in USA, whereas point source pollution is the most important in our study; use of fertilizer is much smaller in developing countries, and the type of agriculture and management practices are distinct. 3. We test whether the chemical composition of streams and their macroinvertebrate communities can be related to land use. Accordingly, we compared the variability of chemical composition and macroinvertebrate communities in the streams of two catchments (Pisca and Cabras) belonging to the same ecoregion, but having different types of land use. 4. The main land use in the Pisca catchment in 1993 was sugar cane (62%), followed by pasture (22%) and urban centres (10%). In contrast, the main land use in the Cabras catchment was pasture (60%), followed by annual crops (13%) and forest (10%); urban centres occupied only 2% of the catchment. 5. In the Cabras catchment, most of the parameters correlated with a land use index (LUI) (Fig. 2). However, only conductivity, major cations and major anions (with exception of sulfate) had a statistically significant correlation coefficient. More than 90% of the variance was explained for these parameters. DIC, NO3 and richness of invertebrates (RI) also strongly correlated with LUI (R 2 = 0.75), although these correlation coefficients were not significant. Total suspended solids (TSS) had a significant correlation with LUI (R 2 = 0.98), but, the correlation was inverse. In the Pisca catchment, conductivity, major cations (with exception of potassium), major anions, and DIC, DO, and DOC had a strong and statistically significant correlation with LUI. Correlation coefficients were also high for respiration rate, although the correlation was not statistically significant.

Neste trabalho teve-se como objetivo testar o modelo CENTURY para simular os efeitos das mudanças de uso da terra nos teores de carbono no solo e na produção primária líquida na bacia do rio Piracicaba, SP. O modelo foi parametrizado e as simulações foram realizadas considerando-se áreas de florestas, pastagens e cana-de-açúcar, dada a sua importância econômica. Os resultados obtidos indicaram que a alteração do uso/cobertura do solo provoca a diminuição do estoque de carbono do solo. As simulações realizadas na transição de uma floresta para cana-de-açúcar indicaram um decréscimo de 28% no estoque de carbono nos primeiros 12 anos, e diminuição de 42% com 50 anos de cultivo do solo com essa gramínea. Na simulação da transição de uma floresta para pasto, seguida do cultivo da cana-de-açúcar, verificou-se que na primeira mudança (floresta-pastagem) a perda de carbono foi de 24%, enquanto na segunda alteração (pastagem-cana) a perda foi de 22%. Com relação à produção primária, os resultados obtidos de floresta (6,6 t ha-1 ano-1), cana-de-açúcar (77, 82, 80 t ha-1 ano-1) e pasto (6,5 t ha-1 ano-1), mostraram-se similares aos valores observados no campo por outros autores.

Assuming the paradigm that catchment vegetation is the main source of particulate organic matter (POM) to rivers, the main objective of this study was to determine what the proportion of original C3 carbon from the forest had already been replaced by C4 carbon from sugar cane and pasture in the rivers of the Piracicaba Basin. In order to achieve this objective, we first produced a detailed landcover map using Landsat5-TM images, and then we measured the carbon stable isotopic composition of the particulate riverine organic matter (δ 13 C-POM) in seven sites along the major rivers and in two sites along a small creek. Sugar cane and pasture (C4 plants) covered almost 60% of the basin area, while silviculture, mostly of other crops, citrus, and forest that are C3 plants, covered 35%. Isotopic studies conducted in large pristine tropical rivers of South America and of Africa have shown that catchment vegetation is the main source of carbon in suspended POM. Our study demonstrates that relatively recent changes (70-80 yr ago) in landcover in the Piracicaba River Basin have already affected the composition of the riverine POM. Therefore, as in natural ecosystems, the vegetation (allochthonous source) plays an important role in the composition of the riverine POM in agricultural systems such as the Piracicaba River Basin. This control can be supported by the good correlation between cumulative area of the basin covered with C4 plants and the δ 13 C of the riverine POM. However, our study, differently from others, also shows that, during the low water period, in situ processes, such as primary production, may be an important source of carbon to the riverine POM.

Concentrations of biogenic gases (O 2 and CO 2 ) and respiration rates were measured at 7 sites along major tributaries of the Piracicaba River to address the effects of sewage loading on aquatic metabolism. Strictly aerobic conditions were observed at upstream sites (less polluted), with concentrations of O 2 at or above and CO 2 slightly above atmospheric equilibrium. Concentrations of biogenic gases were independent of variations in discharge and relatively constant during the sampling period. Respiration rates were significantly higher at upstream sites and CO 2 concentrations were above atmospheric equilibrium. The concentrations of CO 2 at downstream sites were inversely correlated with discharge. At the downstream sites (more polluted), anthropogenic inputs of labile organic matter (sewage) altered the aquatic metabolism by creating a less aerobic environment. At these sites, O 2 concentrations were always below atmospheric equilibrium and directly related to discharge.

O mel é um alimento apreciado por seu sabor característico e pelo seu considerável valor nutritivo. Devido a oferta do produto ser menor que a procura, seu preço é relativamente alto, incentivando sua adulteração. Geralmente, a adulteração do mel é feita através da adição de açúcares comerciais, derivados de cana-de-açúcar e milho. Como essas plantas têm uma composição isotópica do carbono distinta das plantas utilizadas pelas abelhas como fonte de néctar (flores silvestres, citros e eucaliptos), é possível utilizar a composição isotópica do carbono de amostras de mel para se avaliar a adulteração desse produto por açúcares comerciais oriundos da cana e do milho. Foram analisadas amostras de plantas pertencentes ao ciclo fotos-sintético C3, subprodutos de plantas C4 (açúcares comerciais) e 61 amostras de mel obtidas no mercado. As plantas C3 analisadas apresentaram valores de d13C de -28,9±1,1‰ (n=8), enquanto os açúcares apresentaram valores de -11,1±0,7‰ (n=3). Das 61 amostras de mel analisadas, cerca de 8% (5 amostras) tiveram sinais claros de adulteração. A amostra de número 34 teve um valor igual a -12,9‰, indicando que açúcar puro de cana-de-açúcar ou milho estaria sendo comercializado como mel. As amostras 13, 14, 33 e 54 apresentaram valores iguais a -21,0; -19,9; -21,9 e -17,6‰, respectivamente. Esses valores indicam também adição de açúcares de cana-de-açúcar ou milho, no entanto em menor proporção. A metodologia testada neste trabalho foi aprovada como um método simples, confiável e complementar aos métodos químicos e físicos convencionais visando detectar adulteração de mel.Honey is a known product for its nutritional value. Considering that offer is smaller than the market demand, honey is relatively expensive. This fact contribute to the incentive of its adulteration by commercial sugars derived from sugar cane and corn. As these plants have a distinct stable carbon isotope composition than plants commonly used by bees as sources of nectar, it is possible to use the stable carbon isotope composition of honey to detect addition of commercial sugar cane and corn sugars. In this study we analyzed samples of C3 plants commonly used by bees, subproducts of C4 plants, and 61 samples of honey. The d13C of C3 plants values had on average of -28.9±1.1‰ (n=8), while the commercial sugars had an average value of -11.1±0.7‰ (n=3). Approximately 8% (5 samples) of the 61 samples analyzed had d13C values that clearly indicated the addition of commercial sugars (adulteration). The sample number 5 had a d13C valor equal to -12.9‰, indicating that it was all made of commercial sugars. The samples numbers 13, 14, 33, and 54 had values equal to -21.0, -19.9, -21.9 and -17.6‰, respectively. These values also indicated the addition of commercial sugars. The methodology used in this study proved to be a valuable and simple complement to the conventional chemical and physical methods normally used to detect honey adulteration.

We studied the energy flow from C3 and C4 plants to higher trophic levels in a central Amazonian savanna by comparing the carbon stable-isotope ratios of potential food plants to the isotope ratios of species of different consumer groups. All C4 plants encountered in our study area were grasses and all C3 plants were bushes, shrubs or vines. Differences in δ13C ratios among bushes (x¯ = −30.8, SD = 1.2), vines (x¯ = −30.7, SD = 0.46) and trees (x¯ = −29.7, SD = 1.5) were small. However the mean δ13C ratio of dicotyledonous plants (x¯ = −30.4, SD = 1.3) was much more negative than that of the most common grasses (x¯ = −13.4, SD = 0.27). The insect primary consumers had δ13C ratios which ranged from a mean of −29.5 (SD = 0.47) for the grasshopper Tropidacris collaris to a mean of −14.7 (SD = 0.56) for a termite (Nasutitermes sp.), a range similar to that of the vegetation. However, the common insectivorous and omnivorous vertebrates had intermediate values for δ13C, indicating that carbon from different autotrophic sources mixes rapidly as it moves up the food chain. Despite this mixing, the frogs and lizards generally had higher values of δ13C (x¯ = −21.7, SD = 1.6; x¯ = −21.9, SD = 1.8, respectively) than the birds (x¯ = −24.8, SD = 1.8) and the only species of mammal resident in the savanna (x¯ = −25.4), indicating that they are generally more dependent on, or more able to utilise, food chains based on C4 grasses.

The diet of detritivorous fish was analysed at four distinct habitats in a tropical river during the wet and dry seasons. Two methodologies were used to determine the diet of the fish: (1) the direct analysis of the stomach contents; and (2) the use of stable carbon isotopes. Both methods indicated food partitioning among the fish. The stomach contents showed what the fish had ingested when captured and the 13C isotope indicated what it had assimilated over a long period of time. The 13C isotope suggested the existence of sectional differences in the feeding of the detritivorous fish along the river. Plants employing the C4 photosynthesis pathways seem to have little influence on the diet of these fish. This method proved to be more appropriate for the detection of the main food sources of the captured fish.

Water samples were collected from 7 locations along major rivers of Piracicaba River basin for 22 months. The 4 upstream points represent non-polluted sites and the 3 downriver points represent polluted sites. Due to sewage input, concentrations of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), major conservative cations and anions increased significantly in the polluted sites. The major increases were observed for sodium, chloride and sulfate. Nitrate was an exception for this pattern, with similar concentrations between polluted and non-polluted sites. The probable cause was reduction of nitrate to ammonium in the polluted sites, where anoxic conditions prevail. Most of the variables had an inverse correlation with water discharge, especially in the polluted points. The sewage load was diluted by precipitation and surface waters.

Monthly average surface air temperature records from 17 stations in the Brazilian Amazon from 1913 to 1995 were used to compute annual air temperature means. The data were converted into temperature anomalies, as the differences between annual mean temperatures and the mean temperature of a reference period (1958–85). By averaging the anomalies, an increasing trend of 0.56°C century−1 was observed, which is similar to the trend found for the Southern Hemisphere of 0.57°C century−1. The results of two nonparametrical statistical tests showed that the trend became significant in the late 1960s to early 1970s.

The Piracicaba river basin is a subtropical watershed located in the southeastern region of Brazil. With an area of 12 400 km2, the basin is a typical example of new landscape resulting from development in tropical and sub-tropical regions: establishment of intensive industrial and agricultural processes were followed by significant population growth and water management. This scenario has led to significant increase in water demand and decrease in water quality. The main objective of this study is the detection of changes in the patterns of flow and precipitation in the basin, and its possible relation to man-induced changes. Statistical analyses were performed on records of precipitation, evapotranspiration and streamflow, from 1947 to 1991. Precipitation and evapotranspiration totals showed significant increasing trends for the entire basin. From eight streamflow gauge stations, half showed significant decreasing trend. The most probable cause of such trends is the export of water from the basin to the metropolitan region of Sao Paulo city.

Carbon isotope ratios of the main stem in trees, saplings, and seedlings were correlated with their main stem diameter in an Amazonian seasonal forest. This correlation became the basis of using carbon isotope ratios of roots from various levels of the soil profile in order to determine root distribution from emergent, canopy and subcanopy trees, saplings and herbaceous understorey plants. It was observed that the distribution of roots in the soil profile is horizontally and vertically heterogeneous. Pockets of roots from saplings or herbaceous understorey plants were found as deep as 4 m and pockets of roots from emergent trees were found as shallow as 1 m depth.

Recycling of respiratory CO 2 was calculated with a previously developed model using stable isotope ratios and concentration values of ambient CO 2 . Measurements were taken at two different tropical forests in the Amazon basin during the dry season. One forest (Reserva Ducke) was characterized by a closed canopy with lower wind speeds, while the other (Fazenda Vitoria) had a relatively open canopy and higher wind speeds. The closed canopy forest had up to 39% of its respiratory CO 2 recycled at 18 m above the forest floor. Percent recycling in this forest was related to wind speed at the date of collection. Calculations of recycling on the open canopy forest gave values rnaging from 0 to negative. This forest may have ambient CO 2 contamination from charcoal kilns in a nearby town. Thus, calculations of recycling based on isotopic composition of ambient CO 2 for this forest may be incorrect.

The spatial and temporal variability of dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate concentration and total coliform (TC) were investigated at nine sampling stations distributed along the main rivers of the Piracicaba River Basin, a 12,400 km2 catchment located in Sao Paulo State, one of the most developed regions of Brazil. Spatially, a downstream impoverishment of water quality conditions was observed, as seen by the decrease of DO, and increase of BOD, nitrate, and TC. These changes were probably caused by accumulating downstream discharge of domestic and industrial sewage. Temporal evaluation of 18 years of data showed that DO decreased with time for the majority of the sampling stations, while BOD, nitrate, and TC increased. A law, approved at the end of 1991, proposed a new water tax for river water extraction for industrial and agricultural use. The amount of this tax is determined according to the water quality of the extracted water. Therefore, the evaluation of the water quality status in this basin is a first step to help resources managers to determine the values for this tax.

Using a simple isotope mixing model, we evaluated the relative proportion of water vapour generated by plant transpiration and by soil evaporation at two sites in the Amazon basin. Sampling was carried out at two different soil covers (forest and pasture), in a seasonal tropical rainforest at eastern Amazon where major deforestation is the result of land-use change, and compared to a less seasonal central Amazon forest. In both forests, vapour from transpiration was responsible for most, if not all, of the water vapour generated in the forest, while it could not be detected above the grassy pastures. Thus the canopy transpiration may be a major source of water vapour to the forest and perhaps to the atmosphere during the dry season. The results are discussed in relation to predictive models based on net radiation that usually are not able to distinguish between transpiration and evaporation.

The hydrograph separation of the Amazon river was performed using three different methodologies. Were applied isotopic, filter-separation, and mixing methods to estimate the contributions of the surface runoff (event water) and baseflow (pre-event water) components to the total river flow, during the 1973–1974 hydrological years. The importance of the baseflow contribution, mainly during the peak discharge, suggesting that the groundwater plays a much more active and important role in the storm dynamics, was verified. Similar results were obtained for all the methods used, and the applicability of each one was discussed in detail. For the Amazon river basin, the average contribution of the baseflow was 56% of the total river flow, at peak discharge. The average surface runoff contribution, which represents the water capable of mechanical erosion in drainage basins, expressed in terms of the surface runoff coefficient (Kr), was 31.9%, while the mean contribution of the baseflow, expressed by the baseflow coefficient (Kb), was 68.1%.

Background The present study aimed to determine whether the δ13C and δ15N of fingernails (δ13CF and δ15NF, respectively) would exhibit differences between groups from different income levels in the city of Piracicaba, Brazil. Methods In 2010, the fingernails of 273 participants belonging to six income groups were analysed to determine isotopic composition. δ13CF and δ15NF were compared with the stable isotope of a putative diet (δ13CD and δ15ND, respectively), which was estimated via an isotopic mass balance using, as a weighting factor, macronutrient intake by the main food items, as obtained by the 2008–2009 household food purchases conducted by the Brazilian Institute of Geography and Statistics. Results δ13CF values showed a decreasing trend towards the lower income level groups, in accordance with the δ13CD values that showed the same trend. This isotopic change was mainly a result of the higher consumption of beef, bread, soft drinks and dairy by the highest income group; and also as a result of the higher consumption of soybean oil, rice and sugar by the lowest income group. The δ15NF values failed to capture differences in groups between income levels. This outcome was not expected because individuals in a higher income group tend to consume more animal protein and, as a result of the trophic fractionation, have higher δ15N values. Conclusions The combination of household purchase surveys and stable isotopic composition in modern humans is found to be a valuable tool, especially with respect to determining the role of C3 and C4 plants through the complex modern food chain.

Latin America (LA) has many social indicators similar to those of highly developed economies but most frequently falls midway between least developed countries and industrialized regions. To move forward, LA must address uncontrolled urbanization, agricultural production, social inequity, and destruction of natural resources. We discuss these interrelated challenges in terms of human impact on the nitrogen (N) cycle. Human activity has caused unprecedented changes to the global N cycle; in the past century; total global fixation of reactive N (Nr) has at least doubled (1). Excess Nr leaked into the environment negatively affects soils, atmosphere, and water resources in temperate zones (1). In addition to N excess from human impact, mining of natural soil N creates N deficits in some regions (2, 3). Fil: Austin, Amy Theresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina Fil: Bustamante, M. M. C.. Universidade Do Brasilia; Brasil Fil: Nardoto, G. B.. Universidade Do Brasilia; Brasil Fil: Mitre, S. K.. Universidade Do Brasilia; Brasil Fil: Pérez, T.. Instituto Venezolano de Investigaciones Cientificas; Venezuela Fil: Ometto, J. P. H. B.. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Ascarrunz, N. L.. Instituto Boliviano de Investigación Forestal; Bolivia Fil: Forti, M. C.. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Longo, K.. Centro de Previsao de Tempo e Estudos Climaticos. Instituto Nacional de Pesquisas Espaciais; Brasil Fil: Gavito, M. E.. Universidad Nacional Autónoma de México; México Fil: Enrich Prast, A.. Universidade Federal do Rio de Janeiro; Brasil Fil: Martinelli, L. A.. Universidade de Sao Paulo; Brasil

Samples from individuals of the populations of Sotalia guianensis (Guiana) and Pontoporia blainvillei (Franciscana) dolphins living in the Babitonga Bay estuary (26° 28′ S/48° 50′ W), and samples from individuals of a second population of P. blainvillei from a nearshore area (26° 38′ S/48° 41′ W), were collected and analyzed along with their prey between 2000 and 2006, to determine the carbon and nitrogen stable isotope ratios and to verify differences in their feeding ecology. No differences were found in the median ð15N values of Guiana (15.2‰) and Franciscana (15.9‰) dolphins living in Babitonga Bay, nor of nearshore Franciscana (15.0‰) individuals, suggesting no variation in the trophic level of these populations. However, the lack of more information on the isotopic compositions of their putative prey in the nearshore areas prevents the ability to draw definitive conclusions on this issue. The estuarine Franciscana and Guiana dolphin populations presented mean ð13C values of approximately −15.7‰, which were not statistically different from nearshore Franciscana individuals (−14.8‰). Based on stomach content analyses of these species from a previous study, it was reported that there was little overlap in the diet of estuarine Franciscanas and Guiana dolphins. However, based on the similarity of the ð13C values between these two species and of their putative prey, it appears that in fact there is an overlap in the diet of these two species. Based solely on stable isotope analysis, it was not possible to differentiate between estuarine and nearshore Franciscana populations, making it difficult to conclude whether captured nearshore specimens were indeed yearlong residents of these areas. Finally, this study suggests that Franciscana and Guiana dolphin populations are sharing the same resources, mostly L. brevis, D. rhombeus, and S. rastrifer. Therefore, the combination of resource sharing and commercial exploitation of their prey makes these two cetacean species vulnerable. Amostras de tecido de indivíduos pertencentes às populações de Sotalia guianensis (boto-cinza) e Pontoporia blainvillei (toninha) que vivem no estuário da Baía da Babitonga (26° 28′ S/48° 50′ W) e de uma segunda população de P. blainvillei da área costeira (26° 38′ S/48° 41′ W) foram coletadas entre os anos 2000 e 2006 para determinar as composições de isótopos estáveis de carbono e nitrogênio, assim como de suas presas para analisar diferenças na ecologia alimentar. Não foram detectadas diferenças nos valores médios de ð15N entre os botos-cinza (15.2‰) e as toninhas (15.9‰) que vivem na Baía da Babitonga, e entre indivíduos de toninhas da área costeira (15.0‰), sugerindo que não existe variação no nível trófico destas populações. Contudo, a ausência de informações mais completas sobre a composição isotópica das presas na área costeira limita a proposição de conclusões mais definitivas sobre esta temática. As populações estuarinas de toninhas e botos-cinza apresentaram valores médios de ð13C de aproximadamente −15.7‰, que não apresentaram diferença estatística com relação às toninhas da área costeira (−14.8‰). Baseado na análise de conteúdos estomacais destas espécies num estudo anterior sugere-se que não há sobreposição na dieta das toninhas e botos-cinza do estuário. Contudo, baseado na similaridade dos valores de ð13C entre estas espécies e nos distintos valores de ð13C de suas presas, há indícios de que de fato existe uma sobreposição na dieta destas duas populações. Com base apenas na análise de isótopos estáveis não foi possível diferenciar a população estuarina e costeira de toninhas, tornando-se difícil concluir se os indivíduos capturados acidentalmente na área costeira eram residentes de longo prazo. Finalmente, este estudo sugere que toninhas e botos-cinza estão compartilhando os mesmos recursos, principalmente L. brevis, D. rhombeus e S. rastrifer. Portanto, a exploração comercial dessas espécies pode ameaçar a sobrevivência do boto-cinza e das toninhas na Baía da Babitonga.

Interactions between distant places are increasingly widespread and influential, often leading to unexpected outcomes with profound implications for sustainability. Numerous sustainability studies have been conducted within a particular place with little attention to the impacts of distant interactions on sustainability in multiple places. Although distant forces have been studied, they are usually treated as exogenous variables and feedbacks have rarely been considered. To understand and integrate various distant interactions better, we propose an integrated framework based on telecoupling, an umbrella concept that refers to socioeconomic and environmental interactions over distances. The concept of telecoupling is a logical extension of research on coupled human and natural systems, in which interactions occur within particular geographic locations. The telecoupling framework contains five major interrelated components, i.e., coupled human and natural systems, flows, agents, causes, and effects. We illustrate the framework using two examples of distant interactions associated with trade of agricultural commodities and invasive species, highlight the implications of the framework, and discuss research needs and approaches to move research on telecouplings forward. The framework can help to analyze system components and their interrelationships, identify research gaps, detect hidden costs and untapped benefits, provide a useful means to incorporate feedbacks as well as trade-offs and synergies across multiple systems (sending, receiving, and spillover systems), and improve the understanding of distant interactions and the effectiveness of policies for socioeconomic and environmental sustainability from local to global levels. © 2013 by the author(s).

In this paper we calculated soil carbon stocks in Brazil studying 17 paired sites where soil stocks were determined in native vegetation, pastures and crop-livestock systems (CPS), and in other regional samplings encompassing more than 100 pasture soils, from 6.58 to 31.53° S, involving three major Brazilian biomes: Cerrado, Atlantic Forest, and the Pampa. The average native vegetation soil carbon stocks at 10, 30 and 60 cm soil depth were equal to approximately 29, 64, and 92 Mg ha−1, respectively. In the paired sites, carbon losses of 7.5 Mg ha−1 and 11.6 Mg ha−1 in CPS systems were observed at 10 cm and 30 cm soil depths, respectively. In pasture soils, carbon losses were similar and equal to 7.5 Mg ha−1 and 11.0 Mg ha−1 at 10 cm and 30 cm soil depths, respectively. Differences at 60 cm soil depth were not significantly different between land uses. The average soil δ13C under native vegetation at 10 and 30 cm depth were equal to −25.4‰ and −24.0‰, increasing to −19.6‰ and −17.7‰ in CPS, and to −18.9‰, and −18.3‰ in pasture soils, respectively; indicating an increasing contribution of C4 carbon in these agrosystems. In the regional survey of pasture soils, the soil carbon stock at 30 cm was equal to approximately 51 Mg ha−1, with an average δ13C value of −19.67‰. Key controllers of soil carbon stock in pasture sites were sand content and mean annual temperature. Collectively, both could explain approximately half of the variance of soil carbon stocks. When pasture soil carbon stocks were compared with the average soil carbon stocks of native vegetation estimated for Brazilian biomes and soil types by Bernoux et al. (2002) there was a carbon gain of 6.7 Mg ha−1, which is equivalent to a carbon gain of 15% compared to the carbon soil stock of the native vegetation. The findings of this study are consistent with differences found between regional comparisons like our pasture sites and plot-level paired study sites in estimating soil carbon stocks changes due to land use changes.

Across the cratonic landscape of Brazil the Solimoes-Amazon River transports to its delta plain 1240 Mt of suspended sediment derived from Andean erosion and reworks another 3200 Mt of floodplain sediments. Distribution of these sediments has resulted in a variable along-stream pattern of geomorphology. The upstream reaches are characterized by sediment erosion in the main channel and deposition in floodplain channels that are an order of magnitude smaller in discharge than the main channel. Sediment deposition in and migration of the floodplain channels erases oxbow lakes of the main channel and yields an intricate scroll-bar topography that forms the boundaries of hundreds of long, narrow lakes. In contrast, downstream reaches are characterized by channels restricted by stabilizing, long-term, levee building and floodplain construction dominated by overbank deposition. Overbank deposition buries the scroll-bar topography, resulting in a flat floodplain covered by a patchwork of large, more equant, shallow lakes. On the basis of estimated rates of recycling of floodplain sediments, the modern floodplain of the Brazilian Amazon could have been recycled in

The return of water in vapor form from the land to the atmosphere, via plant transpiration and evaporation, is fundamental for the maintenance of the regional water cycle in the Amazon basin. Whereas transpiration, the dominant process, has the extensive vegetation cover as a large single source, evaporation can have several sources, and their relative importance and location are poorly known. The isotopic composition (δ18O and δD) of water from various sources was used to see whether or not specific sources of water vapor to the atmosphere could be determined. It is well established that natural waters fall on a line called the meteoric water line (MWL; the regression of δ18O × δD), with slope equal to eight and an intercept equal to ten. When a water body loses water via evaporation the slope become smaller than eight, typically 5–6. We estimated the slope of the regression of δ18O × δD for several potential sources. We analyzed 1273 samples: 500 of rainfall, 409 of river water, 134 of lake water, 164 of soil water, 40 of throughfall and stemflow water, and 26 of shallow ground-water. We found that large rivers and lakes are likely contributors of evaporated water to the atmosphere. However, as they cover only a small area of the basin, other sources are needed. Probably, evaporated water originates from several small sources that were not detected by the isotopic composition of our data.

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...