Genesis of soils from bauxite in southeastern Brazil : resilication as a soil-forming process.

Pedological studies using X-ray diffraction (XRD), X-ray fluorescence (XRF), optical microscopy, and scanning electron microscopy (SEM-EDS) showed a Xanthic Ferralsol formed from the degradation of bauxite on a slope in the Caparaó region, in southeastern Brazil. We found a decrease in the number and size of bauxite fragments toward the top of the profiles, bauxite fragments that were more degraded at the top of the profiles, transformation of gibbsite into kaolinite, and absolute enrichment in silicon in the mass balance. These indicators suggest that resilication could be the major process responsible for formation of the soil; detailed studies are needed to verify the origin of the silica. The reintroduction of silica into the system occurs by the biogeochemical cycling of vegetation and, in some cases, water table fluctuations, highlighting the role of resilication as a soil-forming process in bauxite-derived soils

Genesis of closed depressions in slopes associated with the aluminous duricrust in the south region of Capara? Ridge, Minas Gerais/Espirito Santo.

A origem das depress?es fechadas associadas ? cobertura later?tica aluminosa nos topos dos morros e ao longo das vertentes na regi?o de Espera Feliz, MG, divisa com Esp?rito Santo, foi pesquisada atrav?s de um levantamento geof?sico da cobertura pedol?gica associado ?s an?lises morfol?gicas (macro e micro) de perfi s de solos. O levantamento geof?sico por GPR, realizado em 2 se??es ao longo de uma vertente, abrangeu duas depress?es consecutivas e foi seguido do levantamento sistem?tico da cobertura pedol?gica por meio da abertura de 5 perfi s (N1, L1, L2, N2 e L3). Foram coletadas amostras deformadas para an?lises f?sicas, mineral?gicas e qu?micas e amostras indeformadas para an?lise micromorfol?gica. No interior das depress?es fechadas foi identifi cado o Neossolo Lit?lico h?mico t?pico e entre as depress?es ocorre o Latossolo Vermelho Amarelo distr?fi co h?mico. A an?lise lateral realizada pelo GPR e a interpreta??o conjunta dos atributos da cobertura revelam um sistema pedol?gico cont?nuo do topo a base da vertente. As diferen?as morfol?gicas que levam a exist?ncia de distintas classes de solos traduzem, neste contexto, a evolu??o pedogeomorfol?gica da vertente e consequente g?nese das depress?es, o que teria ocorrido de maneira distinta ao modelo de subsid?ncia por lixivia??o geoqu?mica, mais amplamente conhecido. Dois momentos s?o reconhecidos: i) a origem de uma cobertura latoss?lica relacionada ao avan?o vertical da degrada??o da bauxita e ? bioturba??o sob condi??es clim?ticas ?midas e ii) remo??o de partes dessa cobertura em condi??es clim?ticas (possivelmente ?ridas) posteriores.The origin of the closed depressions associated with the aluminous duricrust occurring on the tops of the hills and along the hillslope in the region of Espera Feliz city, Minas Gerais state, bordering the Esp?rito Santo state, was investigated through a geophysical survey of soil cover associated with the morphological analysis (macro and micro) in soil profi les. Geophysical survey by GPR held in two sections along a slope, covered two consecutive depressions and was followed by systematic survey of soil cover through the opening 5 profi les (N1, L1, L2, N2 and L3), where deformed samples were collected for chemical, physical and mineralogical analysis and undisturbed samples for micromorphological analysis. Humic Neosols were found inside the closed depressions and Humic Ferralsols were found between the closed depressions. The side analysis performed by GPR and the joint interpretation of the soil properties reveals a persistent pedological system from top to bottom of the slope. So the morphological diff erences that would lead to consider two soil classes are related to the occurency of mass moviments. The origin of the horizon (Bw and A) are related to the vertical advance of bauxite degradation conducted by bioturbation. The aluminous duricrust and its transformation into soil are understood as preceding stages of erosive features formation. Thus, the bauxite in the region would have formed under hot and humid weather conditions and removing parts of the cover in later dry weather conditions

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazonia Sustentavel, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.Keywords: Social–ecological systems, Tropical forests, Land use, Interdisciplinary research, Sustainability, Trade-off

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

Sistemas de alteração e gênese de solos em piroclastos da ilha de Trindade, Atlântico sul

This study aimed to characterize the alteration features comprising the genesis and formation of soils on pyroclasts of Trindade Island (TI), South Atlantic, Brazil. Collections of samples were made at the Holocene Paredão volcano (Profile P1) and the Late Quartenary Morro Vermelho Formation (profiles P2, P3 and P4). The pyroclasts of P1 and P2 are volcanic breccia deposit, whereas of P3 is a lapilli deposit. P4 presents fragments of rocks with mineralogical composition different from other profiles suggesting another event of deposition of pyroclastic bombs. The eruptions associated can be regarded as strombolians. Optical microscope supported by X-ray diffraction analysis revealed a mixture of biotite, goethite, ilmenite, anatase, magnetite, hematite, pyroxene, zeolites, and olivine as their main mineral components. Petrologic analysis shows sideromelane that changes to palagonite, indicating a phreatomagmatic eruption. Infrared analyses in the palagonitized regions revealed the presence of halloysite, suggesting alteration of sideromelane to tubular clay minerals. Amygdales and microfractures are partially or totally filled with zeolites, which are formed by the percolation of water that reacts with the palagonite and precipitation of chemical elements of hydrothermal fluid. Iddingsite and Ti-magnetites occur in the fractures and edges of the olivine. The advance of the alteration towards the soil profile, leaving only relicts of olivine or reaching their total transformation in the upper horizons, shows that weathering is the main process of iddingsite formation. Some Ti-magnetites are zoned with Cr-rich core and Cr-poor edge, suggesting a mantelic origin. The augite and diopside explain the high trace elements contents. Geochemical data show that the pyroclasts are plotting in the ultrabasic and foidites. The soils of P1 and P2 show, respectively, A, Bi, C and decapitated A, C horizons; and P3 and P4 show A and C horizons. The soil profiles show a reddish and brownish clayey matrix and are friable with a plastic consistency. Their microstructures are granular, simple grain and intergrain microaggregate and, the aggregates show undifferentiated b-fabric. The mineralogical constituents of the bulk fraction are biotite, hematite, magnetite, ilmenite, pyroxene, olivine, halloysite, goethite, anatase and rutile. The clay fraction is marked by presence of halloysite, ferrihydrite and little amounts of allophane. All soils can to be classified as non-allophanic Andosols. The predominance of halloysite formed by alteration of sideromelane, suggests that allophane would be an intermediate phase of this rapid transformation favored by climate conditions of the TI. Total geochemistry showed that in all profiles Al, Fe and Ti accumulate due to their low mobility and Ca, Na, K and Mg are the most intensely leached. The profiles located at the lower quotas have higher K and Mg values in A horizon due to the influence of salt sprays and the deposition of chemical elements from the higher regions. Ti, Mn, Fe, Co, Cr, Ni, V, Zr, S were enriched in soil profiles P1 and P3 due to loss of mobile elements during the soil formation process. Zn and Cu concentrate on A horizon of profiles P3 and P4 with higher concentration of organic matter and fragments of unaltered pyroclasts. Leaching of the rare earth elements from higher to the lower slope led to the enrichment of these elements, especially the light rare earth elements, in the low-lying soil. The high-altitude profile showed Ce positive anomaly due to longer exposure to weathering.Cette étude visait à déterminer les caractéristiques d'altération comprenant la genèse et la formation de sols sur les pyroclastes de l'Île de Trindade (IT), Atlantique Sud, Brésil. Les échantillons ont été prélevés au Vulcão do Paredão de l'Holocène (profil P1) et dans la Formation Morro Vermelho du Quaternaire ancien (profils P2, P3 et P4). Les pyroclastes de P1 et P2 sont dépôts de brèches volcaniques, tandis que P3 est un dépôt de lapilli. P4 présente des fragments de roches avec une composition minéralogique différente des autres profils suggérant un autre événement de dépôt de bombes pyroclastiques. Les éruptions associées peuvent être considérées comme stromboliennes. Analyse au microscope optique soutenue par la diffraction des rayons X indiquent un mélange de biotite, de goethite, d'ilménite, d'anatase, de magnétite, d'hématite, de pyroxènes, de zéolites et d'olivine comme minéraux principaux. La microscopie optique montre un sidéromélane qui se transforme en palagonite, indiquant une éruption phréato-magmatique. La microscopie infrarouge dans les zones palagonitisées a identifié l’halloysite, probablement issue de l'altération du sideromélane. Les amygdales et les microfractures sont partiellement ou totalement remplies de zéolites, formées par la percolation de l'eau qui réagit avec la palagonite et la précipitation des éléments chimiques du fluide hydrothermal. Les magnétites-Ti et l’iddingsite sont observées dans les fractures et en bordure des olivines. La progression de l'altération dans le profil du sol, se manifeste par la présence de reliques d'olivine ou sa transformation totale dans les horizons supérieurs, et montre que l'altération est le processus principal de formation des iddingsites. Certaines magnétites-Ti sont zonées avec un enrichissement en Cr au centre, suggérant une origine mantellique. L'augite et le diopside expliquent les teneurs élevées en éléments traces. Les données géochimiques montrent que les pyroclastes sont ultrabasique et föiditique. Les sols de P1 et P2 comportent, respectivement, les horizons A, Bi, C et un A érodé, C, tandis que P3 et P4 sont constitués des horizons A et C. Les sols montrent une matrice argileuse rougeâtre et brunâtre et sont friables avec une consistance plastique. Leurs microstructures sont granulaires, simples microaggrégats de grains et d'intergrains et, les aggrégats sont indifférenciés. Les constituants minéralogiques de la roche sont la biotite, l'hématite, la magnétite, l'ilménite, les pyroxènes, l'olivine, l'halloysite, la goethite, l'anatase et le rutile. La fraction argileuse est marquée par la présence d'halloysite, de ferrihydrite et de petites quantités d'allophane. Tous les sols peuvent être classés comme Andosols non-allophaniques. La prédominance de l'halloysite suggère que l'allophane serait une phase intermédiaire issue de l’altération rapide du sidéromélane favorisée par les conditions climatiques de l’IT. La géochimie totale montre que dans tous les profils Al, Fe et Ti s'accumulent en raison de leur faible mobilité et que Ca, Na, K et Mg sont les plus intensément lixiviés. Les profils des altitudes inférieures présentent des valeurs en K et Mg plus élevées dans l'horizon A en raison de l'influence des projections salines et de dépôt d'éléments chimiques des niveaux supérieurs. Pour P1 et P3, les éléments Ti, Mn, Fe, Co, Cr, Ni, V, Zr, S ont été enrichis dans les sols et leurs concentrations relatives sont liées à perte d'éléments mobiles pendant le processus de formation du sol. Zn et Cu se concentrent sur un horizon A de profils P3 et P4 avec une concentration plus élevée de matière organique et des fragments de pyroclastes inaltérés. Le lixiviation des terres rares de haut vers la pente inférieure a conduit à l'enrichissement de ces éléments, en particulier des terres rares légers, dans un sol à basse altitude. Le profil de haute altitude a montré une anomalie positive en Ce due à une exposition plus longue aux intempéries