Rainfall, runoff and temperature fluctuations in the Amazon basin and oscillation of global climate over the last century

Over the past century, the world's climate has been changing. The rainfall over the continents, the global stream water discharge, the global air temperature and the CO2 content in the atmosphere have together been increasing. However, in the Amazon basin, examination of data existing and the estimation of missing data reveal that for about the past century, between 1910 and 1990, the air temperature has been decreasing, and the rainfall and the river discharge have been increasing but showing very large fluctuations. It is shown that the evolution of the global climate, over continents becoming warmer and wetter, should not mask the following realities: (1) amplitudes of fluctuations are large; (2) regional and global trends do not necessarily move in the same directions and (3) regional and global fluctuations, even if of similar amplitude and of equal periodicity, are not synchronous

Oxidation and reduction rates for organic carbon in the Amazon mainstream tributary and floodplain, inferred from distributions of dissolved gases

Concentrations of CO2, O2, CH4, and N2O in the Amazon River system reflect an oxidation-reduction sequence in combination with physical mixing between the floodplain and the mainstem. Concentrations of CO2 ranged from 150 microM in the Amazon mainstem to 200 to 300 microM in aerobic waters of the floodplain, and up to 1000 microM in oxygen-depleted environments. Apparent oxygen utilization (AOU) ranged from 80 to 250 microM. Methane was highly supersaturated, with concentrations ranging from 0.06 microM in the mainstem to 100 microM on the floodplain. Concentrations of N2O were slightly supersaturated in the mainstem, but were undersaturated on the floodplain. Fluxes calculated from these concentrations indicated decomposition of 1600 g C sq m y(-1) of organic carbon in Amazon floodplain waters. Analysis of relationships between CH4, O2, and CO2 concentrations indicated that approximately 50 percent of carbon mineralization on the floodplain is anaerobic, with 20 percent lost to the atmoshphere as CH4. The predominance of anaerobic metabolism leads to consumption of N2O on the flood plane. Elevated concentrations of CH4 in the mainstem probably reflect imput from the floodplain, while high levels of CO2 in the mainstem are derived from a combination of varzea drainage and in situ respiration

Pré-concentração em linha para a determinação simultânea de ácidos carboxílicos de baixo peso molecular e ânions inorgânicos em amostras de rios da Amazônia empregando cromatografia de íons com detecção por condutividade elétrica

An ion chromatography procedure, employing an IonPac AC15 concentrator column was used to investigate on line preconcentration for the simultaneous determination of inorganic anions and organic acids in river water. Twelve organic acids and nine inorganic anions were separated without any interference from other compounds and carry-over problems between samples. The injection loop was replaced by a Dionex AC15 concentrator column. The proposed procedure employed an auto-sampler that injected 1.5 ml of sample into a KOH mobile phase, generated by an Eluent Generator, at 1.5 mL min-1, which carried the sample to the chromatographic columns (one guard column, model AG-15, and one analytical column, model AS15, with 250 x 4mm i.d.). The gradient elution concentrations consisted of a 10.0 mmol l-1 KOH solution from 0 to 6.5 min, gradually increased to 45.0 mmol l-1 KOH at 21 min., and immediatelly returned and maintained at the initial concentrations until 24 min. of total run. The compounds were eluted and transported to an electro-conductivity detection cell that was attached to an electrochemical detector. The advantage of using concentrator column was the capability of performing routine simultaneous determinations for ions from 0.01 to 1.0 mg l-1 organic acids (acetate, propionic acid, formic acid, butyric acid, glycolic acid, pyruvate, tartaric acid, phthalic acid, methanesulfonic acid, valeric acid, maleic acid, oxalic acid, chlorate and citric acid) and 0.01 to 5.0 mg l-1 inorganic anions (fluoride, chloride, nitrite, nitrate, bromide, sulfate and phosphate), without extensive sample pretreatment and with an analysis time of only 24 minutes.A metodologia analítica foi desenvolvida empregando coluna pré-concentradora AC15 em linha na cromatografia iônica na determinação simultânea de ânions orgânicos e inorgânicos, com uso de coluna de guarda AG15 e analítica AS15, 250 x 4 mm i.d. (Dionex Corp.). O gradiente de concentração do eluente foi fixo em 10,0 mmol.l-1 KOH nos tempos de retenção de 0 até 6,5 min, seguido do aumento da concentração até 45,0 mmol.l-1 KOH a 21 min, imediatamente retornando e mantendo a concentração inicial até o tempo total de análise de 24 min. Os compostos foram separados com boa resolução e deslocados para uma cela de detecção de condutividade elétrica acoplada a um detector eletroquímico. O emprego da coluna pré-concentradora em linha apresentou vantagens analíticas na determinação de rotina dos íons na faixa linear de 0,01 até 1,0 mg l-1 (r=0,9989) de ácidos orgânicos (acético, propiônico, fórmico, butírico, glicólico, pirúvico, tartárico, ftálico, metanossulfônico, valérico, maleico, oxálico e cítrico) e 0,01 até 5,0 mg.l-1 (r=0,9987) de ânions inorgânicos (fluoreto, cloreto, nitrito, brometo, nitrato, sulfato, clorato e fosfato) sem pré-tratamento da amostra. Um tempo de análise de 24 min e limite de detecção de 5 µ.l-1 foram obtidos para os ânions orgânicos ácido ácetico, ácido fórmico, ácido butírico, ácido glicólico, ácido valérico, ácido cítrico e de 10 µg.l-1 para ácido propiônico, piruvato, ácido tartárico, ácido ftálico, ácido metasulfônico e ácido maleico. Para os ânions inorgânicos 2 µg.l-1 de fluoreto, cloreto, nitrato, brometo, sulfato e 10 µg.l-1 de clorato, nitrito e fosfato foram estimados, segundo metodologia sugerida por IUPAC.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The Large Scale Biosphere Atmosphere Experiment in Amazoni

Factors driving the biogeochemical budget of the Amazon River and its statistical modelling Facteurs denext term contrôle du bilan biogéochimique previous termdenext term l'Amazone et modélisation statistique associée

International audienceThe seasonal and interannual fluctuations of the biogeochemical budget (solutes, suspended matter, isotopes) of the Amazon River basin were analyzed, with a special focus on 44 physicochemical parameters monitored over the period 1982-1984 during the Carbon in the AMazon River Experiment (CAMREX) project. The relevant factors driving this variability were identified and sorted through the implementation of a statistical-regressive model coupled to variance analysis. Basically, the compositional fluctuations in the Amazon River are related (1) to the variable contribution of major tributaries (variable regional source) to the river flow but also (2) to the variable contribution of hydrological sources, (3) to river processes, i.e. in-stream diagenesis and sediment dynamics and (4) to the hydrological budget of the floodplains. Their respective contributions to the variability of chemical signals observed in the stream waters depend on which parameter was investigated but their combination explains on average 85% of the observed variability. The variability related to regional sources was captured by the compared measures of flow discharge and biogeochemical fluxes at the outlet of the major tributaries. The variability of hydrological sources was described by the variable contribution of three runoffs of distinct but constant composition: forwarded direct runoff, delayed floodplain runoff and baseflow. Several methods were tested to depict the seasonal and interannual variations of their individual discharges. Biologically-mediated processes were related to a hydrobiological index IBIO = [O2]-[CO2] which allows tracking the nature of the dominant ecological regime (autotrophy vs. heterotrophy). The alteration of chemical signals related to the intermittent discharge of the floodplains (where specific processes occur such as: gas exchanges at the air-water interface, sorption of dissolved organic matter, chemical weathering, deposition vs. remobilization of sediments, etc.) was simulated by taking into account the default of hydrological balance between inflows and outflows, used as a marker of floodplains discharge. This analysis shows that the chemical baseline observed in the waters of the Amazon River is mostly acquired upstream from the junction of major tributaries with the Amazon main reach. Les fluctuations saisonnières et interannuelles du bilan biogéochimique (solutés, matière particulaire, isotopes) du fleuve Amazone ont été analysées, avec une attention particulière apportée à 44 paramètres physicochimiques mesurés entre 1982 et 1984 dans le cadre du programme CAMREX. Les facteurs exerçant une influence significative sur cette variabilité ont été identifiés et hiérarchisés par le biais d'un modèle statistique couplé à une analyse previous termdenext term variance. Les variations previous termdenext term composition des eaux previous termdenext term l'Amazone sont fondamentalement associées (1) à previous termlanext term contribution variable previous termdenext term ses affluents majeurs (source régionale variable) au débit total, mais aussi (2) à previous termlanext term contribution variable des pôles previous termdenext term mélange hydrologiques, (3) à des processus fluviaux correspondant au régime hydrobiologique et à previous termlanext term dynamique sédimentaire et (4) au bilan hydrologique des plaines d'inondation. Leurs contributions respectives à previous termlanext term variabilité des signaux chimiques observés dans les eaux du fleuve dépendent du paramètre considéré, mais leur combinaison explique en moyenne 85 % previous termde lanext term variabilité observée. previous termLanext term variabilité associée aux contributions régionales variables est appréhendée en procédant aux bilans entrées-sorties des débits et flux biogéochimiques. previous termLanext term variabilité previous termdenext term contribution des pôles previous termdenext term mélange est décrite par previous termlanext term contribution variable previous termdenext term trois écoulements previous termdenext term compositions distinctes mais constantes : l'écoulement direct à expression précoce, l'écoulement local previous termdenext term vidange alluviale à expression différée et l'écoulement previous termdenext term base. Douze méthodes ont été testées afin previous termdenext term décrire les variations saisonnières et interannuelles des débits individuels previous termdenext term chaque pôle previous termdenext term mélange. Les processus contrôlés par le vivant sont appréhendés à partir d'un indice hydrobiologique IBIO = [O2]-[CO2] qui permet previous termdenext term déterminer previous termlanext term nature du régime hydro-écologique dominant (autotrophe vs. hétérotrophe). L'altération des signaux chimiques générée par previous termlanext term vidange intermittente des plaines d'inondation (au niveau desquelles ont lieu des processus spécifiques : échanges gazeux, sorption previous termdenext term matière organique dissoute, érosion chimique, dépôt vs. remise en suspension previous termdenext term sédiments, etc.) est simulée en prenant en compte le défaut previous termdenext term bilan hydrologique entrées-sorties utilisé comme marqueur previous termdenext term débit des plaines d'inondation. Cette analyse montre que le bruit previous termdenext term fond chimique observé dans les eaux du fleuve Amazone est principalement acquis en amont des confluences entre le tronçon fluvial étudié et les principaux affluents qui l'alimentent

Groundwater quality comparison between rural farms and riparian wells in the western Amazon, Brazil

Groundwater quality of a riparian forest is compared to wells in surrounding rural areas at Urupá River basin. Groundwater types were calcium bicarbonated at left margin and sodium chloride at right, whereas riparian wells exhibited a combination of both (sodium bicarbonate). Groundwater was mostly solute-depleted with concentrations within permissible limits for human consumption, except for nitrate. Isotopic composition suggests that inorganic carbon in Urupá River is mostly supplied by runoff instead of riparian groundwater. Hence, large pasture areas in addition to narrow riparian forest width in this watershed may have an important contribution in the chemical composition of this river.FAPESPCNPq - CT-HIDROCNPq - Milêni

Implicancias de la falta de un plan de sucesión en una Empresa Familiar

Este trabajo aborda la situación problemática de una empresa familiar, que enfronta la falta de un plan de sucesión y ambigüedad en las responsabilidades, con el fin de abordar esta situación se plantearon tres alternativas, como el Desarrollo de un Plan de Sucesión y Definición de Roles Claros, el Plan Estratégico de Sucesión Gradual y Progresiva, y la Creación de una Comisión de Sucesión y Comunicación Abierta, las cuales no son excluyentes para este trabajo, puesto que se analizó la alternativa prioritaria a tomar en consideración. Determinando que el "Desarrollo de un Plan de Sucesión" es la estrategia más idónea, debido a su capacidad para abordar directamente la situación problemática y garantizar la continuidad y el éxito de la empresa en un futuro sostenible. Está elección se justificó por la inversión a largo plazo, la cohesión familiar y la necesidad de abordar una cuestión que debió considerarse desde el inicio. Dicho plan de sucesión no solo resuelve problemas inmediatos, sino que sienta las bases para el crecimiento continuo y el éxito constante, fortaleciendo los lazos familiares y promoviendo un entorno de trabajo saludable. Además de ello, se analizaron teorías como la Teoría del Cambio Organizacional Incremental, los Roles de la Familia Empresaria y la teoría del ciclo de Vida de la Empresa Familiar, las cuales producto de su aplicación proporcionaron soluciones efectivas frente a la problemática de sucesión, subrayando la importancia del cambio organizacional, el aprendizaje organizativo y la definición de responsabilidades claras, para garantizar un futuro exitoso y sostenible.This work addresses the problematic situation of a family-owned company, which is facing the lack of a succession plan and ambiguity in responsibilities. In order to address this situation, three alternatives were proposed, such as the Development of a Succession Plan and Definition of Clear Roles, the Strategic Plan for Gradual and Progressive Succession, and the Creation of a Succession Committee and Open Communication. These alternatives are not mutually exclusive for this work, as the priority alternative to be considered was analyzed. It was determined that the "Development of a Succession Plan" is the most suitable strategy due to its ability to directly address the problematic situation and ensure the continuity and success of the company in a sustainable future. This choice was justified by the long-term investment, family cohesion, and the need to address an issue that should have been considered from the beginning. This succession plan not only solves immediate problems but also lays the foundation for continuous growth and constant success, strengthening family bonds and promoting a healthy work environment. In addition, theories such as the Theory of Incremental Organizational Change, the Roles of the Business Family, and the theory of the Family Business Life Cycle were analyzed, and their application provided effective solutions to the succession issue, emphasizing the importance of organizational change, organizational learning, and the definition of clear responsibilities to ensure a successful and sustainable future.Trabajo de Suficiencia Profesiona

Amazon deforestation alters small stream structure, nitrogen biogeochemistry and connectivity to larger rivers

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 105 (2011): 53-74, doi:10.1007/s10533-010-9540-4.Human activities that modify land cover can alter the structure and biogeochemistry of small streams but these effects are poorly known over large regions of the humid tropics where rates of forest clearing are high. We examined how conversion of Amazon lowland tropical forest to cattle pasture influenced the physical and chemical structure, organic matter stocks and N cycling of small streams. We combined a regional ground survey of small streams with an intensive study of nutrient cycling using 15N additions in three representative streams: a second-order forest stream, a second-order pasture stream and a third-order pasture stream that were within several km of each other and on similar soils and landscape positions. Replacement of forest with pasture decreased stream habitat complexity by changing streams from run and pool channels with forest leaf detritus (50% cover) to grass-filled (63% cover) channel with runs of slow-moving water. In the survey, pasture streams consistently had lower concentrations of dissolved oxygen and nitrate (NO3-) compared with similar-sized forest streams. Stable isotope additions revealed that second-order pasture stream had a shorter NH4+ uptake length, higher uptake rates into organic matter components and a shorter 15NH4+ residence time than the second-order forest stream or the third-order pasture stream. Nitrification was significant in the forest stream (19% of the added 15NH4+) but not in the second-order pasture (0%) or third-order (6%) pasture stream. The forest stream retained 7% of added 15N in organic matter compartments and exported 53% (15NH4+ =34%; 15NO3- = 19%). In contrast, the second-order pasture stream retained 75% of added 15N, predominantly in grasses (69%) and exported only 4% as 15NH4+. The fate of tracer 15N in the third-order pasture stream more closely resembled that in the forest stream, with 5% of added N retained and 26% exported (15NH4+ = 9%; 15NO3- = 6%). These findings indicate that the widespread infilling by grass in small streams in areas deforested for pasture greatly increases the retention of inorganic N in the first- and second-order streams, which make up roughly three-fourths of total stream channel length in Amazon basin watersheds. The importance of this phenomenon and its effect on N transport to larger rivers across the larger areas of the Amazon Basin will depend on better evaluation of both the extent and the scale at which stream infilling by grass occurs, but our analysis suggests the phenomenon is widespread.This work was supported by grants from the NASA Large-Scale Biosphere and Atmosphere Experiment (NCC5-686), the National Science Foundation (DEB-0315656) and the Fundação de Ámparo à Pesquisa do Estado de São Paulo

Losses by volatilization of 15 N-urea and 15N-ammonium sulphate from a calcareous soil of the central coastal region of Peru

Num solo calcário (Entissolo) da parte central da região costeira do Peru, foram estudadas, em casa de vegetação, as perdas por volatilização do N-ureia (10,191% átomos 15N) e N-sulfato de amônio (7,801% átomos 15N), aplicados como adubo de cobertura na cultura de milho. Nos vasos com 1.500g de terra, o N foi aplicado na dose de 150 μg/g. Os adubos localizados de quatro maneiras (na superfície do solo seco, superfície do solo úmido, superfície do solo seco com irrigação imediata e enterrado a 4cm em solo úmido), foram aplicados quando as plantas de milho (quatro/vaso) tinham quinze dias após a emergência (DAE). As perdas do N-fertilizante, por volatilização, foram calculadas através do balanço de massa do N aplicado, no final do experimento (45 DAE). Encontrou-se que: a) a ureia (65%) superou o sulfato de amônio (52%) no aproveitamento pela cultura, sendo que o aproveitamento dos adubos foi maior quando foram aplicados na superfície do solo seco ou enterrados em solo úmido; b) a ureia deixou mais N residual no solo, mas não houve diferenças significativas nas formas de localização; c) a perda do N-sulfato de amônio (39%), por volatilização, superou sensivelmente a ureia (23,6%); d) as perdas do N-fertilizante aplicado na superfície do solo úmido (42%) ou seco com irrigação imediata (37%) superaram sensivelmente as aplicações na superfície de solo seco (23,4%) ou enterrado em solo úmido (22%).A study was performed in greenhouse to investigate the volatilization losses on nitrogen from 15N labelled urea (10.191 atom % 15N) and ammonium sulphate (7.801 atom % 15N) applied to pots of a calcareous soil (Entisol) from the central coastal region of Peru. The pots contained 1.5 kg of soil and were planted with four maize plants. The labelled N was added at a rate of 150 μg N.g-1 soil at 15 days after emergence (DAE) of the maize. The N fertilizer were applied in four different ways: on the surface of the dry soil, on the surface of the wetted soil, on the surface of the dry soil but immediately irrigated, or buried at a depth of 4cm in wetted soil. The losses of fertilizer N, by volatilization were calculated from a mass balance of the applied labelled N at the end of the experiment (45 DAE). It was found that: a) a greater proportion of the N from urea (65%) was taken up by the plant than that provided by ammonium sulphate (52%) and fertilizer use efficiency was greater when the fertilizers were applied to the surface of the dry soil or buried in wetted soil; b) the urea left more residual N in the soil but there were no significant differences between the addition methods; c) the loss of N from ammonium sulphate 39%), by volatilization, was greater than that from urea (23,6%); d) the losses of fertilizer N applied to the surface of the wetted soil (42%) or from that applied to dry soil which was immediately irrigated (37%) were significantly greater than when the fertilizer was applied to the surface of dry soil (23,4%) or buried in wet soil (22%)

Simulation of the effects of land use changes in soil carbon dynamics in the Piracicaba river basin, São Paulo State, Brazil

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.The objective of this study was to test adequability of the CENTURY model to simulate the effects of land use changes on soil carbon content and net primary production to specific subtropical Brazilian environmental conditions. After parameterization, simulations were performed for forested areas, pasture and sugarcane cultures which have economical importance and representative areal extension in the Piracicaba River basin, São Paulo State, Brazil. The results obtained indicate that changes in use/cover from forest to agricultural practices resulted in lower soil carbon stocks. The simulations of the transition from forest to sugarcane indicated a decrease of 28% in soil carbon stocks for the first 12 years and 42% for 50 years of sugarcane cultivation. The simulation of the transition from forest to pasture and then to sugarcane resulted in a 24% loss of soil carbon stock for the first transition (forest-pasture) and of 22% for the second one (pasture-sugar-cane). The net primary production results obtained for forest (6.6 ton ha-1 yr-1), sugarcane (77, 82, 80 ton ha-1 yr-1) and pasture (6.5 ton ha-1 yr-1) were similar to those observed by other authors in field measurements