Epigeous termite mounds are frequently observed in pasture areas, but the processes regulating their population dynamics are poorly known. This study evaluated epigeous termite mounds in cultivated grasslands used as pastures, assessing their spatial distribution by means of geostatistics and evaluating their vitality. The study was conducted in the Cerrado biome in the municipality of Rio Brilhante, Mato Grosso do Sul, Brazil. In two pasture areas (Pasture 1 and Pasture 2), epigeous mounds (nests) were georeferenced and analyzed for height, circumference and vitality (inhabited or not). The area occupied by the mounds was calculated and termite specimens were collected for taxonomic identification. The spatial distribution pattern of the mounds was analyzed with geostatistical procedures. In both pasture areas, all epigeous mounds were built by the same species, Cornitermes cumulans. The mean number of mounds per hectare was 68 in Pasture 1 and 127 in Pasture 2, representing 0.4 and 1 % of the entire area, respectively. A large majority of the mounds were active (vitality), 91 % in Pasture 1 and 84 % in Pasture 2. A “pure nugget effect” was observed in the semivariograms of height and nest circumference in both pastures reflecting randomized spatial distribution and confirming that the distribution of termite mounds in pastures had a non-standard distribution.

Potassium (K) is an important limiting factor of tree growth, but little is known of the effects of K supply on the long-distance transport of photosynthetic carbon (C) in the phloem and of the interaction between K fertilization and drought. We pulse-labelled 2-year-old Eucalyptus grandis L. trees grown in a field trial combining K fertilization (+K and −K) and throughfall exclusion (+W and −W), and we estimated the velocity of C transfer by comparing time lags between the uptake of 13CO2 and its recovery in trunk CO2 efflux recorded at different heights. We also analysed the dynamics of the labelled photosynthates recovered in the foliage and in the phloem sap (inner bark extract). The mean residence time of labelled C in the foliage was short (21–31 h). The time series of 13C in excess in the foliage was affected by the level of fertilization, whereas the effect of throughfall exclusion was not significant. The velocity of C transfer in the trunk (0.20–0.82 m h−1) was twice as high in +K trees than in −K trees, with no significant effect of throughfall exclusion except for one +K −W tree labelled in the middle of the drought season that was exposed to a more pronounced water stress (midday leaf water potential of −2.2 MPa). Our results suggest that besides reductions in photosynthetic C supply and in C demand by sink organs, the lower velocity under K deficiency is due to a lower cross-sectional area of the sieve tubes, whereas an increase in phloem sap viscosity is more likely limiting phloem transport under drought. In all treatments, 10 times less 13C was recovered in inner bark extracts at the bottom of the trunk when compared with the base of the crown, suggesting that a large part of the labelled assimilates has been exported out of the phloem and replaced by unlabelled C. This supports the ‘leakage-retrieval mechanism’ that may play a role in maintaining the pressure gradient between source and sink organs required to sustain high velocity of phloem transport in tall trees.

The purpose of this article is to evaluate the performance, in terms of specific consumption in g/kWh, of biodiesel produced from soybean oil, palm oil and residual frying oil, by means of ethylic and methylic routes, in blending percentages of 20% and 50%, at different power levels, for electric power generation from stationary internal combustion engines. The results are evaluated by Tukey′s range test, which enables the comparison of any and all contrasts between two averages of a variable. The results evidence that the 20% blend of biodiesel from soybean oil produced by methylic route seems to be the one whose performance is the closest to the reference fuel′s, and that the proportion of biodiesel has affected more significantly the performance of the blend tested than the type of raw material or route, in relation to the specific consumption for all power levels.

Brazilian shell mounds are relicts of prehistoric settlements characterized as distinct features on the sandy coastal plain, sandy bars of coastal lagoons and rocky island. They are composed of shells of edible marine mollusks, fish remains and wildlife bones intermixed with sand. In the coastal lagoon region of the Rio de Janeiro state these shell mounds range in age between 5100 and 1300 cal BP. In this study we analyzed the geochemistry of the bones of the whitemouth croaker that primarily offers insight on the nature of bone diagenesis and its use for radiochronology and as isotope paleo-thermometer. The x-ray diffractograms of bones from the Tarioba shell mound exhibit elevated calcite profiles in contrast to a reduced hydroxyapatite concentration. Two peaks of quartz and the presence of feldspar provide evidence of exogenous materials, e.g., sand or silt particles, infilling hollow spaces within the fish bones. The Beirada and the Ponte do Girau shell mounds are characterized by the highest peaks of apatite relative to calcite, which is clearly different from the result obtained for Tarioba. The Manitiba profile is similar to the Tarioba profile except for calcite peaks that are approximately three times lower than those for Tarioba. At a depth of 25 cm in the Tarioba shell mound, the redox sensitive index of diagenetic alteration reaches its maximum value, suggesting a zone of accumulation in the soil horizon redox condition. The δ18O derived temperatures profile based on mollusks showed a consistent range from 18.1 to 24.1 °C, indicating seasonal events of intense upwelling of the South Atlantic Central Water breaking the mean warm surface conditions of the Brazil Current. Diagenetic imprints of Tarioba shell mound suggest humid burial conditions with the loss of hydroxyapatite and the enrichment of exogenous calcite. Drier depositional environmental conditions are indicated in the Ponte do Girau and the Beirada shell mounds, while intermediary depositional environmental conditions characterize the Manitiba shell mound. In the period represented by the shell mound samples, the sea level exhibited significant oscillations and portions of the inner shelf were exposed, which may have resulted in an anomalous derived temperature records. These results are compatible with events of anomalous temperatures occurring in the sea level during the time span of occupation of these shell mounds.

The East Continental Shelf (ECS) of Brazil is a hotspot of endemism and biodiversity of reef biota in the South Atlantic, hosting a number of Marine Protected Areas (MPAs). Connectivity of MPAs through larval dispersal influences recruitment, population dynamics, genetic structure and biogeography in coral reef ecosystems. Connectivity of protected reef ecosystem in the ECS was investigated with a hydrodynamic model (ROMS) forcing an Individual Based Model (IBM—Ichthyop), and used groupers (genus Mycteroperca) as functional group. The hydrodynamic output from ROMS was compared with satellite data and showed good agreement with observed surface fields. Eggs were released, in IBM experiments, from April to September along six years (2002–2007) in five MPAs along the ECS. Intrannual variability in recruitment and self-recruitment of grouper larvae was observed, as well as a negative correlation of these population parameters with total Kinetic Energy (KE) used as a metric of the physical environment. Higher KE leads to increased offshore advection of larvae, reduced total recruitment and connectivity of MPAs. Our results indicate high and uni-directional connectivity between MPAs from north to south influenced by the Brazil Current flowing in the same direction. Results also showed that some MPAs act predominantly as “sink” while others are mainly “source” areas.

The Amazon Basin is a special contributor to global biogeochemistry, particularly from the white water region related to the Andes mountains, a source of major Amazon river tributaries. White water composition and properties are rarely determined. Therefore, it is essential to know the spatial distribution and temporal variability of these waters to assess possible human influences on their chemical characterization. In this paper, a study performed in the Southwestern Amazon region, examining the chemical composition of the Acre River water is presented. This part of the Amazon Basin has not been studied sufficiently to determine the geochemistry of its white waters. pH, electric conductivity (EC), turbidity, and concentration of metals, anions and dissolved organic carbon (DOC) were measured from 2008 to 2014. Approximately 60% of the pH measurements had values between 6.5 and 7.3; 55% of the conductivity measurements had values between 30 and 60 -S cm-1; and 50 % of the turbidity measurements had values less than 100 NTU. The major soluble elements were Ca, Si and K. These species have a natural origin (clay minerals and quartz). Toxic elements (e.g., V, Ni, Cr and Pb) and the anions NO3- and SO42- were present at concentrations below the Brazilian Standards. The Na+, SO42- and Al concentrations are seasonally variable depending on water discharge. Major ions such as Mg and Ca showed a positive linear correlation with DOC.

The modeling of seasonal and interannual streamflow forecasting at northeastern Brazil represents a great relevance problem to the use and management of water resources; which demands greater prediction ability models. This is still a difficult task to solve due to the seasonal and interannual climate variability at the semi-arid region. This work presents the artificial neural networks (ANN) as an alternative for modeling the seasonal to interannual climate prediction,. For the development of this task the hydropraphic Oros weir Basin was chosen due to its importance as water resources in the State of Ceara. According to recent studies, the temperatures of the North Atlantic, South Atlantic and equatorial Pacific can be satisfactorily as predictors for the Northeast climate. The proposed model predicts, in July, the next rainy season (January to June) river flow regime. This time frame is of great relevance for the allocation of water resources. Among the studied models, those using the average temperature anomalies of April, May and June preceding the predicted year as input data showed the highest Nash-Suttcliffe efficiency (0.80).

O Semiárido brasileiro está sujeito a secas cada vez mais severas em razão das mudanças climáticas, o que exige a adoção de medidas mitigadoras e adaptativas. Essas medidas serão mais eficientes se favorecerem ações proativas que minimizem a vulnerabilidade e gerenciem o risco de secas. A captação e o armazenamento da água de chuva em cisternas foram idealizados como medidas de gestão do risco e têm sido apontados como estratégia de sucesso no processo de adaptação de comunidades vulneráveis à seca. No entanto, os mecanismos de suporte ao uso das cisternas possuem falhas, favorecendo seu uso na gestão de crise para o armazenamento não água de chuva, mas da fornecida por carros-pipas. Com base nesses pressupostos e utilizando dados disponibilizados pelo Observatório da Seca, apresentam-se reflexões acerca da eficácia das cisternas como medida de adaptação e gestão do risco. Foi observado que as cisternas são úteis na gestão do risco e da crise, no entanto ainda há dificuldades em se mensurar sua contribuição para a redução da vulnerabilidade à seca. Além disso, os problemas relacionados ao sistema podem contribuir para seu emprego prioritário na gestão da crise, ao invés de assumir o seu papel genuíno de adaptação e gestão de riscos.

The thermodynamics of the seasonal evolution of the Southwestern Tropical Atlantic Warm Pool (hereafter SWTAWP), which is delimited by the 28 °C isotherm, is investigated using the Regional Ocean Modeling System (ROMS). Results indicate that the net heat flux is responsible for the appearance and extinction of the SWTAWP. From March to May, the SWTAWP attains its maximum development and sometimes merges with equatorial warm waters towards the African continent, whose development follows the same period. Along the equator, the combination of oceanic terms (i.e., advection and diffusion) is important to promote the separation – when it occurs – of equatorial warm waters from southwestern tropical waters, which develops off the Brazilian coast. An analysis of the relative contribution of the temperature tendency terms of the mixed layer (ML) heat budget over the appearance, development and extinction of the SWTAWP is also done. The most important term for warming and cooling inside of the ML is the net heat flux at the sea surface. The ML is heated by the atmosphere between October and April, whereas the upper ocean cools down between May and September. The highest heat content values occur during the lower-temperature period (August to October), which is linked to the deepening of the ML during this time period. The horizontal advection along the equator is important, particularly at the eastern domain, which is influenced by the cold tongue. In this area, the vertical diffusive term is also significant; however, it presents values near zero outside the equator. These results contribute to a better understanding of the behavior of the heat budget within the tropical Atlantic, as previous studies over this region focused along the equator only.

The ocean temperatures and zonal currents at the equatorial Atlantic simulated by an improved version of the Brazilian earth system model (BESM), with changes in the cloud cover scheme and optical properties of the atmospheric component, are analyzed and compared to those obtained from a previous version of BESM and also from other seven selected CMIP5 models. It is shown that this updated version of BESM, despite some persistent biases, more accurately represents the surface temperature variation at the Equator and the equatorial thermocline east–west slope. These improvements are associated to a more realistic seasonal cycle achieved for the Atlantic equatorial undercurrent, as well as sea surface temperatures and zonal wind stress. The better simulation of the equatorial undercurrent is, in its turn, credited to a more realistic representation of the surface wind position and strength at the tropical Atlantic by the coupled model. With many of the systematic errors noticed in the previous version of the model alleviated, this version of BESM can be considered as a useful tool for modelers involved in Atlantic variability studies.

The purpose of this article is to evaluate the performance, in terms of specific consumption in g/kWh, of biodiesel produced from soybean oil, palm oil and residual frying oil, by means of ethylic and methylic routes, in blending percentages of 20% and 50%, at different power levels, for electric power generation from stationary internal combustion engines. The results are evaluated by Tukey′s range test, which enables the comparison of any and all contrasts between two averages of a variable. The results evidence that the 20% blend of biodiesel from soybean oil produced by methylic route seems to be the one whose performance is the closest to the reference fuel′s, and that the proportion of biodiesel has affected more significantly the performance of the blend tested than the type of raw material or route, in relation to the specific consumption for all power levels.