Central Amazon Region Research Articles

Long Term Analysis of Optical and Radiative Properties of Aerosols in the Amazon Basin

ABSTRACT The Amazon region is an excellent laboratory for analysis of natural aerosols in the wet season; however, in the dry season the biomass burning emissions highly influence it, which considerably alters the physical and chemical properties of the atmosphere. We analyzed long-term time series (2000–2017) of optical and radiative properties of aerosols during dry and rain seasons from nine AERONET stations located in the Amazon Basin (Western Brazil). Aerosols have been classified into two groups: organic carbon (OC) and elemental carbon (EC), which allowed quantification of their effects on the radiative forcing for these sites. It was possible to conclude that the optical depth values of aerosols (AOD 500 nm), which remained in a downward inclination beginning in 2010 to 2012, returned to rise since 2013. The analysis showed that the fraction of biogenic particles varied from approximately 38% to 67% at the site of Manaus EMBRAPA. However, for ATTO this fraction remained practically constant throughout the year, around 68% as the fraction of OC-EC went from approximately 16 to 27%. In that way, the study found that in the central Amazon region, in the dry season, the OC fraction generates instantaneous effects of up to –100 W m–2 in the radiative surface forcing (FR-Surface), while in the Cerrado region (Cuiaba) the instantaneous values reached up to –350 W m–2. The impact of the primary biogenic particles on the radiative flux resulted in a mean, approximately –20 W m–2 FR-Surface, representing 45% of the total effect caused by aerosols in the Amazon.

Estimating groundwater resources of the Içá-Solimões Aquifer System in the Urucu Oil Province Central Amazon Region, Brazil, focused on a balance between availability and water demand

ABSTRACT Hydrogeologic information is still scarce in the Amazon region being required more studies for improving the understanding of local hydrogeologic contexts. The goal of this paper, focused on the Urucu Oil Province, Brazilian Central Amazon, is to quantitatively estimate groundwater resources of the Içá-Solimões Aquifer System (ISAS) in the region. The work focuses on a balance between availability and water demand, considering current and future uses, contributing to a sustainable and integrated use of groundwater. Cartographic, lithologic and geophysical logs were analyzed coupled with ISAS hydraulic data (transmissivity, hydraulic conductivity, and storativity) and its local aquifer geometries, as well as the potentiometric surface map to estimate values of total and renewable groundwater resources, sustainable yields, and well-field facility capacities. Results showed the portion of the Içá-Solimões Aquifer System has a total groundwater resource of 0.45 km3. As there is a groundwater consumptive projection to 2050 close to 2.7 x 10-3 km3 yr–1 and the aquifer system has a sustainable yield of 3 x 10-3 km3 yr–1, the current resource allocation for future consumption rate appears to be sustainable.

Amazonian dark earths in the fertile floodplains of the Amazon River, Brazil: an example of non-intentional formation of anthropic soils in the Central Amazon region

ABSTRACT Amazonian dark earths (ADEs) are fertile soils created by pre-Columbian Amerindian societies of the Amazon Basin. However, it is still not clear whether these soils were produced intentionally to improve infertile Amazonian upland soils or if they resulted from the accumulation of organic matter from sedentary settlements. This study characterizes the ADEs found in the naturally fertile alluvial floodplains of the Amazon River in the Central Brazilian Amazon according to total, exchangeable, and available contents of elements and organic carbon in soil profiles. ADEs contained higher levels of available elements and total P, Ca, Zn, and Cu. High total Cr, Ni, Co, and V content in these soils indicate that mafic minerals contributed to their composition, while higher contents of P, Zn, Ba, and Sr indicate anthropic enrichment. The presence of ADEs in floodplain areas strongly indicates non-intentional anthropic fertilization of the alluvial soils, which naturally contain levels of P, Ca, Zn, and Cu higher than those needed to cultivate common plants. The presence of archaeological sites in the floodplains also shows that pre-Columbian populations lived in these regions as well as on bluffs above the Amazon River.

Distribution of Metals in the Waters and Sediments of Rivers in Central Amazon Region, Brazil

Seasonal concentrations of total, particulate and dissolved Al, Cu, Cd, Cr, Fe, Pb and Ni were analyzed in surface water and total metals in sediment samples from black and whitewater rivers within the Itacoatiara City, Central Amazon. Metals concentrations in water and sediment samples demonstrated that even though urbanization and agricultural practices are common in this region. Metal concentrations in sediments samples are acceptable regarding the recommended levels for protection of aquatic life. From this work, which is the first trace elements study in the main tributaries from Itacoatiara region, we conclude that metals are present in a particulate form, being easier to be transported to other aquatic bodies. During flooding periods an increase of Al, Fe and total organic compound (TOC) in almost water sampling points was observed.

On two species of Ichthyouris (Nematoda: Pharyngodonidae) parasites of Mesonauta festivus (Pisces: Cichlidae) in the Brazilian Amazon region

Two species of nematodes belonging to the genus Ichthyouris Inglis, 1962 ( I. ro and I. bursata ), were collected from the cichlid fish Mesonauta festivus in the central Brazilian Amazon region. Both species are reported in this locality for the first time. I. bursata is reported in a new host, M. festivus , and this is the first report of I. ro parasitizing its type host in Brazil. We provide a more detailed description for I. ro , including morphological aspects that were not mentioned in the original description.

Observations of sesquiterpenes and their oxidation products in central Amazonia during the wet and dry seasons

Biogenic volatile organic compounds (BVOCs) from the Amazon forest region represent the largest source of organic carbon emissions to the atmosphere globally. These BVOC emissions dominantly consist of volatile and intermediate-volatility terpenoid compounds that undergo chemical transformations in the atmosphere to form oxygenated condensable gases and secondary organic aerosol (SOA). We collected quartz filter samples with 12 h time resolution and performed hourly in situ measurements with a semi-volatile thermal desorption aerosol gas chromatograph (SV-TAG) at a rural site ("T3") located to the west of the urban center of Manaus, Brazil as part of the Green Ocean Amazon (GoAmazon2014/5) field campaign to measure intermediate-volatility and semi-volatile BVOCs and their oxidation products during the wet and dry seasons. We speciated and quantified 30 sesquiterpenes and 4 diterpenes with mean concentrations in the range 0.01-6.04 ngm-3 (1-670ppqv). We estimate that sesquiterpenes contribute approximately 14 and 12% to the total reactive loss of O3 via reaction with isoprene or terpenes during the wet and dry seasons, respectively. This is reduced from ~ 50-70 % for within-canopy reactive O3 loss attributed to the ozonolysis of highly reactive sesquiterpenes (e.g., β-caryophyllene) that are reacted away before reaching our measurement site. We further identify a suite of their oxidation products in the gas and particle phases and explore their role in biogenic SOA formation in the central Amazon region. Synthesized authentic standards were also used to quantify gas- and particle-phase oxidation products derived from β-caryophyllene. Using tracer-based scaling methods for these products, we roughly estimate that sesquiterpene oxidation contributes at least 0.4-5 % (median 1 %) of total submicron OA mass. However, this is likely a low-end estimate, as evidence for additional unaccounted sesquiterpenes and their oxidation products clearly exists. By comparing our field data to laboratory-based sesquiterpene oxidation experiments we confirm that more than 40 additional observed compounds produced through sesquiterpene oxidation are present in Amazonian SOA, warranting further efforts towards more complete quantification.

Heating-Induced Transformations of Atmospheric Particles: Environmental Transmission Electron Microscopy Study.

Environmental transmission electron microscopy was employed to probe transformations in the size, morphology, and composition of individual atmospheric particles as a function of temperature. Two different heating devices were used and calibrated in this work: a furnace heater and a Micro Electro Mechanical System heater. The temperature calibration used sublimation temperatures of NaCl, glucose, and ammonium sulfate particles, and the melting temperature of tin. Volatilization of Suwanee River Fulvic Acid was further used to validate the calibration up to 800 °C. The calibrated furnace holder was used to examine both laboratory-generated secondary organic aerosol particles and field-collected atmospheric particles. Chemical analysis by scanning transmission X-ray microscopy and near-edge fine-structure spectroscopy of the organic particles at different heating steps showed that above 300 °C particle volatilization was accompanied by charring. These methods were then applied to ambient particles collected in the central Amazon region. Distinct categories of particles differed in their volatilization response to heating. Spherical, more-viscous particles lost less volume during heating than particles that spread on the imaging substrate during impaction, due to either being liquid upon impaction or lower viscosity. This methodology illustrates a new analytical approach to accurately measure the volume fraction remaining for individually tracked atmospheric particles at elevated temperatures.

How Do Environmental Conditions Influence Vertical Buoyancy Structure and Shallow-to-Deep Convection Transition across Different Climate Regimes?

Abstract We developed an entraining parcel approach that partitions parcel buoyancy into contributions from different processes (e.g., adiabatic cooling, condensation, freezing, and entrainment). Applying this method to research-quality radiosonde profiles provided by the Atmospheric Radiation Measurement (ARM) program at six sites, we evaluated how atmospheric thermodynamic conditions and entrainment influence various physical processes that determine the vertical buoyancy structure across different climate regimes as represented by these sites. The differences of morning buoyancy profiles between the deep convection (DC)/transition cases and shallow convection (SC)/nontransition cases were used to assess preconditions important for shallow-to-deep convection transition. Our results show that for continental sites such as the U.S. Southern Great Plains (SGP) and west-central Africa, surface conditions alone are enough to account for the buoyancy difference between DC and SC cases, although entrainment further enhances the buoyancy difference at SGP. For oceanic sites in the tropical west Pacific, humidity dilution in the lower to middle free troposphere (~1–6 km) and temperature mixing in the middle to upper troposphere (>4 km) have the most important influences on the buoyancy difference between DC and SC cases. For the humid central Amazon region, entrainment in both the boundary layer and the lower free troposphere (~0–4 km) have significant contributions to the buoyancy difference; the upper-tropospheric influence seems unimportant. In addition, the integral of the condensation term, which represents the parcel’s ability to transform available water vapor into heat through condensation, provides a better discrimination between DC and SC cases than the integral of buoyancy or the convective available potential energy (CAPE).

Morphological diversity and identification key for landraces of the Amerindian yam in central Amazon

Abstract: The objective of this work was to select an optimal set of morphological descriptors, in order to characterize the phenotipical diversity of Amerindian yam (Dioscorea trifida) landraces cultivated in the municipality of Caapiranga, in the central Amazon region of Brazil, and to develop a botanical identification key for them. A collection of 140 accessions and an experimental plot with a representative sample of 20 landraces were used to test 64 morphological descriptors for the aerial and subterranean plant parts. Forty-eight descriptors were selected, of which 13 were for tubers, 12 for stems, 14 for leaves, and 9 for inflorescences and seed. A cluster analysis based on the morphological data showed the formation of two landrace groups with greater similarity: white and purple pulp tubers. The results provide tools for in situ and ex situ conservation and for plant breeding programs, considering the importance of maintaining and recognizing the value of Ameridian yam as an important native genetic resource for food security in the region.

Genetic diversity of Gossypium barbadense from the central Brazilian Amazon

ABSTRACT The Amazon Basin is a center of diversity of Gossypium barbadense and the strategy for conservation of this genetic resource depends on the knowledge of the diversity maintained in Amazonas State. During two expeditions, in 2012 and 2014, plants were collected in ten municipalities in the state of Amazonas, in the central Brazilian Amazon region. The molecular diversity was estimated by SSR markers for 50 samples collected in 2012. The morphological diversity of 24 plants collected in 2014 was assessed ex situ and compared to that of 50 plants of the same and other cotton varieties from other Brazilian states. Most of plants evaluated in situ in Amazonas had purple petioles and veins (82%), associated to medicinal use, and kidney seeds (78%). The ex situ morphological analysies showed that G. barbadense plants from the Amazonas state: i) presented higher similarity to cotton plants from other northern Brazilian states, and ii) were grouped separately from those of other northern Brazilian states by descriptor analysis. Both the molecular (H=0.41) and morphological (H=0.38±0.02) diversity among the collected plants was considered intermediary. Our study indicates the distinctiveness of Amazon cottons, and contributes to demonstrate the discrimination power of multicategorical traits.

Using Satellite Error Modeling to Improve GPM-Level 3 Rainfall Estimates over the Central Amazon Region

This study aims to assess the characteristics and uncertainty of Integrated Multisatellite Retrievals for Global Precipitation Measurement (GPM) (IMERG) Level 3 rainfall estimates and to improve those estimates using an error model over the central Amazon region. The S-band Amazon Protection National System (SIPAM) radar is used as reference and the Precipitation Uncertainties for Satellite Hydrology (PUSH) framework is adopted to characterize uncertainties associated with the satellite precipitation product. PUSH is calibrated and validated for the study region and takes into account factors like seasonality and surface type (i.e., land and river). Results demonstrated that the PUSH model is suitable for characterizing errors in the IMERG algorithm when compared with S-band SIPAM radar estimates. PUSH could efficiently predict the satellite rainfall error distribution in terms of spatial and intensity distribution. However, an underestimation (overestimation) of light satellite rain rates was observed during the dry (wet) period, mainly over rivers. Although the estimated error showed a lower standard deviation than the observed error, the correlation between satellite and radar rainfall was high and the systematic error was well captured along the Negro, Solimões, and Amazon rivers, especially during the wet season.

Color vision impairment with low-level methylmercury exposure of an Amazonian population – Brazil

Land exploitation that follows deforestation and mining can result in soil erosion and the release of mercury to the waters of rivers in the Amazon Basin. Inorganic mercury is methylated by bacteria that are present in the environment and it serves as a source of human contamination through fish consumption in the form of methylmercury. Long-term exposure to low-level methylmercury in the riverside populations can lead to nervous system alterations, some of which are visual impairments such as loss of luminance contrast sensitivity, restricted visual fields and color vision defects. The present study sought to examine color vision in a group of adults living in the central Brazilian Amazon who were exposed to low-levels of methylmercury. Total Hg concentrations were measured from hair collected at the time of the testing. The D15d and FM100 color vision arrangement tests were applied in a population of 36 (22 males) and 42 (25 males), respectively. Controls were healthy volunteers from the cities of São Paulo for the D15d and Belém for the FM100. There was a statistically significant difference in performance between those who were exposed and controls for both tests (p < 0.01 and p < 0.0001, respectively, Mann-Whitney U test), meaning that adults living in this region of the Amazon made more mistakes on both tests when compared to controls. A linear regression was performed using Hg concentrations and test scores. Hg concentrations accounted for 7% and 2% of color D15d and FM100 arrangement test errors, respectively. Although other studies have previously found color vision impairment in the Amazon, they tested inhabitants on the east side of the Amazon, while this study was conducted in the central Amazon region and it is the first study in a population with no direct contact with the Hg source of contamination. These results suggest that long-term exposure to low-level methylmercury in riverside populations is more widely spread in the Amazon Basin than previously reported. This information is needed to implement public health policies that will ensure a safer environment for the Amazonian population.

The use of Pedotransfer functions and the estimation of carbon stock in the Central Amazon region

Computer models have been used to assess soil organic carbon (SOC) stock change. Commonly, models require to determine soil bulk density (Db), a variable that is often lacking in soil data bases. To partly overcome this problem, pedotransfer functions (PTFs) are developed to estimate Db from other easily available soil properties. However, only a few studies have determined the accuracy of these functions and quantified their effects on the final quality of the spatial variability maps. In this context, the objectives of this study were: i) to develop one PTF to estimate Db in soils of the Brazilian Central Amazon region; ii) to compare the performance of PTFs generated with three other models generally used to estimate Db in soils of the Amazon region; and iii) to quantify the effect of applying these PTFs on the spatial variability maps of SOC stock. Using data from 96 soil profiles in the Urucu river basin in Brazil, a multiple linear regression model was generated to estimate Db using SOC, pH, sum of basic cations, aluminum (Al+3), and clay content. This model outperformed the three other PTFs published in the literature. The average estimation error of SOC stock using our model was 0.03 Mg C ha−1, which is markedly lower than the other PTFs (1.06 and 1.23 Mg C ha−1, or 15 % and 17 %, respectively). Thus, the application of a non-validated PTF to estimate Db can introduce an error that is large enough to skew the significant difference in soil carbon stock change.

Farm-forestry in the Peruvian Amazon and the feasibility of its regulation through forest policy reform

In 2015 the Peruvian government launched a new set of regulations associated with the forest law aimed to increase competiveness of the timber sector, ensure the conservation and sustainable production of timber on public and private forestlands, and improve rural livelihoods. Small-scale timber producers have been marginalized in the sector in the past, and the new regulations claim to provide pathways to formalization for these actors. We draw on policy analysis and field research in the central Amazon region of Peru using mixed methods to characterize smallholder on-farm timber production and evaluate the feasibility of the new regulatory mechanisms for formalizing small-scale timber producers. Through examining a case study on the production and sale of the fast-growing pioneer timber species Guazuma crinita, locally known as bolaina, we found a diversity of management practices, with the strongest reliance on natural regeneration in agricultural fallows, an informal supply chain, and no case of formal documentation at time of sale. We assessed that none of the new regulatory mechanisms will accommodate the sale of timber produced in agricultural fallow stands. We recommend the inclusion of fallow timber in the new forest plantation registry, which could result in the formalization of the supply chain and create an incentive to increase production by small-scale producers.

Crop yield, genetic parameter estimation and selection of sacha inchi in central Amazon1

ABSTRACT In Brazil, sacha inchi oil is produced by hand from plant materials with no breeding or detailed information about the chemical composition of seeds. In addition, most of the current information on the agronomic traits of this species originates from research carried out in the Peruvian Amazon. In order to promote the research and cultivation of sacha inchi in the Brazilian territory, this study aimed to analyze, in the central Amazon region, different accessions of this oilseed for characteristics of production and quality of fruits and seeds, as well as to estimate genetic parameters, through mixed models, with identification of superior accessions, for breeding purposes. A total of 37 non-domesticated accessions were evaluated in a randomized block design, with five replications and two plants per plot. The average oil content in seeds was 29.07 % and unsaturated fatty acids amounted to 91.5 % of the total fat content. For the yield traits, the estimates of individual broad-sense heritability were moderate (~0.33), while the heritability based on the average of progenies resulted in a selective accuracy of approximately 0.85. The use of the selection index provided simultaneous gains for yield traits (&gt; 40 %) and oil yield. A high genetic variability was observed for the main traits of commercial interest for the species, as well as promising perspectives for the development of superior varieties for agro-industrial use.

Characteristics and Diurnal Cycle of GPM Rainfall Estimates over the Central Amazon Region

Studies that investigate and evaluate the quality, limitations and uncertainties of satellite rainfall estimates are fundamental to assure the correct and successful use of these products in applications, such as climate studies, hydrological modeling and natural hazard monitoring. Over regions of the globe that lack in situ observations, such studies are only possible through intensive field measurement campaigns, which provide a range of high quality ground measurements, e.g., CHUVA (Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GlobAl Precipitation Measurement) and GoAmazon (Observations and Modeling of the Green Ocean Amazon) over the Brazilian Amazon during 2014/2015. This study aims to assess the characteristics of Global Precipitation Measurement (GPM) satellite-based precipitation estimates in representing the diurnal cycle over the Brazilian Amazon. The Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) and the Goddard Profiling Algorithm—Version 2014 (GPROF2014) algorithms are evaluated against ground-based radar observations. Specifically, the S-band weather radar from the Amazon Protection National System (SIPAM), is first validated against the X-band CHUVA radar and then used as a reference to evaluate GPM precipitation. Results showed satisfactory agreement between S-band SIPAM radar and both IMERG and GPROF2014 algorithms. However, during the wet season, IMERG, which uses the GPROF2014 rainfall retrieval from the GPM Microwave Imager (GMI) sensor, significantly overestimates the frequency of heavy rainfall volumes around 00:00–04:00 UTC and 15:00–18:00 UTC. This overestimation is particularly evident over the Negro, Solimões and Amazon rivers due to the poorly-calibrated algorithm over water surfaces. On the other hand, during the dry season, the IMERG product underestimates mean precipitation in comparison to the S-band SIPAM radar, mainly due to the fact that isolated convective rain cells in the afternoon are not detected by the satellite precipitation algorithm.

First record of Vampyrodes caraccioli (Thomas, 1889) (Chiroptera, Phyllostomidae) in the state of Amazonas and its updated distribution in Brazil

Abstract: The present note reports the first record of Vampyrodes caraccioli in the Brazilian state of Amazonas, and the central Amazon region, based on 44 specimens caught in the Auati-Paraná Extractive Reserve, north bank of the Solimões/Amazonas River. Our record fills a distribution gap of this species in the Brazilian Amazon and illustrates that the current knowledge on the distribution of Amazonian bats is far from complete.

Estudio etnozoológico kichwa de la nutria gigante Pteronura brasiliensis (Zimmerman, 1780) en la baja Amazonía central del Ecuador

The giant otter Pteronura brasiliensis is the largest mustelid of Neotropical riparian and lacustrine environments. It is endangered throughout the Amazon basin, and in Ecuador is critically endangered because of intensive hunting in past decades, especially in the northeast of the country. Very little is known about their status in the central Amazon region of Ecuador, but it is presumed the existence of more stable populations than those of the northeast remnant populations. The territory of the Pastaza province covers a major portion of the central Amazon and is still well preserved because it is the birthplace of various indigenous peoples for whom the giant otter is a protective spirit. Currently, the contribution of knowledge of local communities is being recognized as an important element for the monitoring and conservation of wildlife. In this context, this study proposes to document the ethnozoological Kichwa knowledge about the distribution, biology and uses of the giant otter in the border area of Pastaza. Interviews were conducted with 12 fishermen from the Ancestral People of the Kawsak Sacha territory. Fishermen provided information on new sites in Pastaza where there are still populations of giant otters. This article also provides unpublished data on prey, predators, size and composition of groups sighted, indirect traces, times of increased sightings, daily schedule of activity, breeding season, uses and spiritual value of the giant otter from the Kichwa ethno-knowledge. This allows us to suggest the need for further research in ethnozoology among local communities, as an strategy to promote the conservation of threatened wildlife species in the Amazon, from a more inclusive and equitable perspective.

Unexplored Amazonian diversity: rare and phylogenetically enigmatic tree species are newly collected

The Amazon is renowned to hold an unprecedented, yet poorly­known or unexplored plant diversity. This study aimed to report new collections on five rare or little­known and phylogenetically enigmatic trees, Aguiaria excelsa (Malvaceae, Bombacoideae), Hylocarpa heterocarpa (Humiriaceae), and the papilionoid legumes Monopteryx uaucu , Petaladenium urceoliferum , and Uleanthus erythrinoides , that became available after recent fieldwork in the western and central Brazilian Amazon region. All five genera, except for Monopteryx , are monospecific and represented in herbaria by only the type or at most few collections made more than 30 years ago. Comments on morphological affinities, never­seen­before photographs, and a distribution map of all species are given. A lectotype for U. erythrinoides is here designated. We also provide a complete taxonomic description for P. urceoliferum , whose pods until presently were unknown. Since these genera are missing branches in the molecular phylogenetic trees of Leguminosae, Humiriaceae, and Malvaceae, the opportunity to include them in future phylogenetic studies will certainly clarify the evolutionary history and taxonomy of their respective families.

Sarcophagidae (Diptera) with forensic potential in Amazonas: a pictorial key

First and foremost, forensic entomology requires the correct identification of the specimens found on a corpse. Among the fly families of greatest forensic importance, the Sarcophagidae (flesh flies) has fewer published keys for the identification of species. Also, identification of flesh flies is not a trivial task due to the complexity of the diagnostic characters found in the male genitalia. To fill this lacuna, here we provide a pictorial key to the species of Sarcophagidae of potential forensic importance found in the central Amazon region of Brazil. This key includes pictures of the main diagnostic characters for 23 species in four genera of Sarcophaginae. As a consequence of preparing this key, we discovered and present new species records for central Amazon.