Resumen Objetivo: Evaluar el alcance, las características y el riesgo de suicidio de los indígenas de Tabatinga, en la Amazonia brasileira. Métodos: Se utilizó una estrategia de vigilancia activa del suicidio y se examinaron los registros de mayores de 9 años, de 2007-2011, del Ministerio de Salud, la Secretaría Municipal de Salud, el Distrito Sanitario Especial Indígena Alto Río Solimões, el Hospital Militar de Tabatinga, la Fundación Nacional del Indio y la notaría del Registro Civil. Las tasas ajustadas se calcularon utilizando el método directo, según la edad. Se realizó un análisis descriptivo y se consideró que las pruebas de hipótesis eran significativas si p < 0,05. Resultados: El alcance del suicidio indígena fue del 82,8%, ya que 11 (17,2%) se clasificaron como suicidios ocultos. Alrededor del 70,0% de la probabilidad de suicidio de los varones se situó a los 15-29 años y la de las mujeres, a los 12-20 años. En el 17,2% de la muestra, se registró consumo de alcohol antes de la muerte y relación parental entre las víctimas. La tasa de mortalidad ajustada corregida fue 111,7/100.000 (IC95%, 84,6-148,6). Conclusiones: El riesgo de suicidio de los indígenas de Tabatinga es muy alto. Las estrategias de afrontamiento deben considerar la compleja relación entre el suicidio y el consumo de alcohol, las diferencias de sexo y la existencia de grupos vulnerables, como los jóvenes, especialmente aquellos con parientes cercanos que ya cometieron suicidio.

Abstract Objective: To evaluate the coverage, characteristics and the risk of suicide in the indigenous people of Tabatinga in the Brazilian Amazon. Methods: An active surveillance strategy for suicide cases was used: records of the Ministry of Health, the Municipal Health Secretariat, the Special Indigenous Health District of the Upper River Solimões (Distrito Sanitario Especial Indígena Alto Río Solimões), the Military Hospital of Tabatinga, the National Indian Foundation (Fundación Nacional del Indio) and the civil registry offices were examined from 2007 to 2011 for individuals over 9 years of age. Adjusted rates were estimated using the direct method and according to age. A descriptive analysis was performed and the hypothesis tests were considered significant if p-values were <0.05. Results: The coverage of indigenous suicide was 82.8%, since 11 (17.2%) were classified as hidden suicides. For men between 15 and 29 years of age, and for women aged from 12 to 20 years, the probability of suicide was around 70.0%. In 17.2% of the sample there was a record of alcohol consumption before death and relationship between victims. The corrected adjusted mortality rate was 111.7/100,000 (95% CI, 84.6-148.6). Conclusions: The risk of suicide in the indigenous people of the Tabatinga is very high. Coping strategies should consider the complex relationship between suicide and alcohol consumption, gender differences and the existence of vulnerable groups, such as young people, especially those with close relatives who have committed suicide.

Resumo Terras Pretas de Índio (TPI) são solos com elevada fertilidade criados pelas sociedades ameríndias pré-colombianas na bacia amazônica. Ainda não existe um consenso se esses solos foram formados intencionalmente para melhorar a fertilidade dos solos distróficos de terra firme da Amazônia ou se resultaram da acumulação de material orgânico em assentamentos sedentários. O objetivo desta pesquisa foi realizar uma caracterização pedogeoquímica de TPI localizadas em áreas de várzeas naturalmente férteis do rio Solimões na Amazônia Central brasileira. Foram analisados os teores totais, trocáveis e disponíveis de elementos e carbono nos solos. As TPI mostraram altos conteúdos trocáveis e disponíveis de P, Ca, Zn e Cu. Elevados conteúdos totais de Cr, Ni, Co e V indicam contribuição de minerais máficos na gênese dos solos, enquanto que teores elevados de P, Zn, Ba e Sr nas TPI indicam enriquecimento antrópico. A ocorrência de TPI em áreas de várzea é uma forte evidência da fertilização não intencional dos solos de várzea, os quais, em condições naturais, apresentam teores de P, Ca, Zn e Cu acima dos níveis críticos para muitas culturas. A presença de sítios arqueológicos em áreas de várzea mostra que as populações pré-colombianas habitaram as várzeas e os interflúvios do rio Solimões.

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.

The results of the analysis of vegetable microremains contained in two sets of pipes from archaeological sites on the banks of the River Plate are presented in this article. The artefacts are a pipe with pre-Hispanic characteristics from the town of Pipinas (Punta Indio) and a set of nineteenth-century kaolin pipes from Magdalena Department. The aim of this paper is to present evidence of the use of plants associated with smoking in the River Plate coastal strip and evaluate the use of local flora for smoking. The reference collection and the methodology used to identify microremains of each context are presented. Traits related to wild autochthonous species such as Ephedra spp., Jodina rhombifolia, Schinus and Celtis were identified, as well as anatomical elements corresponding to the leaves of other taxa.

Presentamos los resultados del análisis de microrrestos vegetales contenidos en dos conjuntos de pipas provenientes de sitios arqueológicos de la ribera rioplatense. Se trata de una pipa de características prehispánicas de la localidad de Pipinas (Punta Indio) y de un conjunto de pipas de caolín del siglo XIX del partido de Magdalena. El objetivo es presentar evidencias del uso de plantas asociadas al hábito de fumar en la franja costera rioplatense y evaluar el uso de la flora local como fumatorio. Se presentan la colección de referencia y la metodología utilizada para la identificación de microrrestos de cada contexto. Se identificaron rasgos afines a especies autóctonas silvestres como Ephedra spp., Jodina rhombifolia, Schinus longifolia y Celtis ehrenbergiana, además de elementos anatómicos correspondientes a hoja de otros taxa.

Abstract During the turn of the twentieth century anticolonial nationalism in British India was tinged by an irresolvable contradiction posed by the defense of a radical rhetoric of national emancipation and a political practice incapable of questioning hierarchical social structures of caste. This contributed to the growth of an unresolved ambiguity during this period between a marked radicalism with regards to opposition to the structures and formations of the state and an emphasis on the importance of its transformation on the one hand, and, on the other, a deep conservatism regarding internal social hierarchies. This ambiguity has had clear effects upon the evolution of the practices and imagination of politics in contemporary India. It has been shared by figures ranging from stalwarts’ supporters of secular nationalism as conceived by the Congress and defendants of the Gandhian legacy based on the importance of swaraj as autonomy, to diverse interpreters of Marxism. At the same time, this ambiguity has been important not only to practices and forms of government, but also to traditions and imaginaries of protest in postcolonial India. In this article, we will explore the presence of this ambiguity in the public debate of British India during these decades through the analysis and juxtaposition of two moments of the intellectual history of India and, more specifically, Bengal. The first one, well known and widely studied, is marked by the nationalist critique of colonial economic policies during the last half of the nineteenth century. This body of critique includes the thought and work of recognized figures of nineteenth century Indian liberalism, such as Dadabhai Naoroji, R. C. Dutt and Prithwis Chandra Ray. The second, considerably less studied, encompasses a set of writings dealing with the relevance of the caste system for the sake of understanding the expansion of certain ideas and tenets of left wing and socialist European radicalism in India at the turn of the twentieth century. By focusing on this material, I am interested in arguing that the radicalism of the nationalist anticolonial movement in India which stemmed from the thrust of early twentieth century swadeshi agitations was revolutionary only in antiimperialist terms and when referring to the need to transform the unjust and oppressive structures of the colonial state. On the contrary, this broad current of nationalism remained profoundly conservative with regards to the internal hierarchies of Indian society.

Resumen Durante las últimas décadas del siglo XIX y las primeras del XX, una irresoluble contradicción entre la retórica radical dirigida a la emancipación nacional y la práctica política incapaz de cuestionar jerárquicas estructuras sociales de casta, empapó el proyecto nacionalista anticolonial indio en su conjunto. Esto ha contribuido al desarrollo de una ambigüedad no resuelta entre, por un lado, un marcado radicalismo en lo que concierne a la oposición a las estructuras y las formas del Estado y, por otro, el conservadurismo frente a las jerarquías internas de la sociedad durante este periodo. Esta ambigüedad ha tenido efectos claros en el desarrollo de las prácticas y los imaginarios de la política en la India independiente. De ella han participado figuras y corrientes que van desde el nacionalismo secular del Partido del Congreso y la adopción del legado gandhiano basado en la idea del swaraj o autogobierno como autonomía, hasta los diferentes intérpretes del corpus marxista en la India contemporánea. De igual forma, es una ambigüedad que marca no sólo las prácticas de gobierno y administración, sino también, y en igual medida, los imaginarios de protesta y oposición al poder. En este artículo me interesa explorar la presencia y las premisas de esta ambigüedad fundacional a través de un estudio del debate público de la India británica en las últimas décadas del siglo XIX y las primeras del XX basado en el análisis y la yuxtaposición de dos momentos de su historia intelectual y, en especial, de la región de Bengala. El primero, de sobra conocido y analizado a fondo por historiadores del colonialismo y el nacionalismo en India, concierne a la crítica nacionalista a la pobreza generada por las políticas económicas del Estado colonial a lo largo del siglo XIX. Esta corriente de crítica anticolonial incluye los argumentos de figuras canónicas del liberalismo indio, como Dadabhai Naoroji, R. C. Dutt o Prithwis Chandra Ray, así como de otros miembros de la intelligentsia decimonónica. El segundo, considerablemente menos estudiado, abarca un conjunto de escritos que abordan la relevancia del sistema de castas para entender la expansión en India de ideas y principios asociados con el radicalismo de izquierda de tintes socialistas a partir del tercer cuarto del siglo XIX. A través del análisis de este material me interesa afirmar que el radicalismo del nacionalismo anticolonial indio que surge del movimiento swadeshi -que defendió diversos programas que iban desde el socialismo revolucionario hasta la sarvodaya gandhiana- representó un programa revolucionario sólo en términos antiimperialistas y respecto a la transformación de las estructuras del Estado, mientras que permaneció profundamente conservador en su postura acerca de las jerarquías internas de la sociedad india.

The Río de la Plata Estuary (RdlP) is a fluviomarine system that drains into the Southwestern Atlantic Ocean with the Paraná and Uruguay rivers as main tributaries. The estuary is fed by a 3,100,000 km2 catchment area which extends over the territories of Argentina, Paraguay, Brazil, Bolivia and Uruguay (Acha et al., 2008). The RdlP exhibits significant natural decadal- and annual-scale, hydrodynamic and oceanographic variability associated with the Pacific Decadal Oscillation (PDO), the Atlantic Multidecadal Oscillation (AMO) and the El Niño/ La Niña Southern Oscillation (ENSO) (Depetris and Pasquini, 2007b; Chiessi et al., 2009; Garreaud et al., 2009). Such variability affects the moisture budget over the surrounding continental areas and leads, thus, to changes in the river discharge. PDO is associated with ENSO as both appear to display similar hydrological responses, though their inherent mechanisms are not yet fully understood (Garreaud et al., 2009). In this sense, warm and cold PDO phases strongly resemble El Niño and La Niña events, respectively (Garreaud et al., 2009). During El Niño episodes, an increase in precipitation over the RdlP drainage basin is commonly observed (Boulanger et al., 2005; Camilloni, 2005; Garreaud et al., 2009; García-Rodríguez et al., 2014), and consequently increased Paraná and Uruguay river discharges are displayed (Depetris and Pasquini, 2007a). Campos et al. (1999) have recorded a freshwater plume of low salinity and temperature (32, 18 ºC respectively) associated with an increase in RdlP discharge during the El Niño event of 1997, expanding northwards up to 23ºS. Furthermore, during negative AMO phases it was recorded an increasing trend on the precipitations over the SE South America (SESA) and, as a consequence, a concomitant increase in the Rivers Paraná and Uruguay discharge was recorded, while the opposite pattern was observed during positive phases (Chiessi et al., 2009). The aim of this paper is to infer the link between changes in the delivery of terrigenous sediment to the adjacent Atlantic Ocean with recorded hydrological variability of the RdlP. To achieve this, we used sedimentological and geochemical proxies from two sediment cores, which were retrieved from the inner continental shelf off Uruguay and encompass the past 100 AD. Sediment Core GeoB 13813-4 was taken from the inner-shelf “RdlP paleo-valley mudbelt” (Fig. 1;34°44’13’’S, 53°33’16’’W) during research cruise M76/3a (Krastel et al., 2012; Lantzsch et al., 2014). Sediment Core BAR1 was retrieved in the innershelf “Barra del Indio” zone (Fig. 1; 35°03’00’’S, 56°09’00’’W), performed by the Faculty of Sciences, Universidad de la República (Uruguay). For Core GeoB 13813-4, we analyzed the relative abundance of major elements (Ca and Ti) obtained by an X-ray fluorescent sediment core scanner AVAATECH and the Ca/Ti ratio was used to infer continental versus marine influence. This chemical elemental ratio was chosen according to previous successful applications within the Atlantic Ocean (Chiessi et al., 2009; Mahiques et al., 2009; Govin et al., 2012; Bender et al., 2013; Burone et al., 2013). Furthermore, the arithmetic mean grain size distribution was studied from both sediment cores, using the GRADISTAT program (Grain Size Distribution and Statistics Package for the Analysis of Unconsolidated Sediments) version 8 (Blott and Pye, 2001) (Fig. 4). For Core GeoB 13813-4 grain size were obtained by Laser Particle Sizer LS200 and for Core BAR1 were obtained by Malvern Mastersizer 2000 Laser analyser. The chronology from both cores was assessed by 210Pbxs dating (Table 1 and Fig. 2; Appleby, 2001; 2008). For core BAR1 we selected the CRS (Constant Rate Supply) model (which is highly used for estuarine systems), while for GeoB 13813-4 the CFCS (Constant Fluxe: Constant Sedimentation Rate) model was applied (Appleby, 2008; Bernal et al., 2010). In the last case, the decision of using the CF-CS model was due to the lack of a complete 210Pb dataset, which would bring very high sedimentation rates uncertainties (Sanchez-Cabeza and Ruiz-Fernández, 2012). To assess the climatic variability over the past century as inferred from the sediment proxies, we evaluated the climatic indices PDO and Southern Oscillation Index (SOI), of the Joint Institute for the Study of the Atmosphere and Ocean, University of Washington (http://jisao.washington.edu), as well as the AMO from the NOAA (http://www.aoml. noaa.gov/phod/amo_faq.php). We further compared these data with temporal series (encompassing the last century) of the Paraná and Uruguay fluvial discharges (http://www.hidricosargentina. gov.ar/acceso_bd.php), river-flow anomalies were calculated following the approach of Piovano et al. (2004). The generated proxy data were analyzed by running cluster analyses using the stratigraphically constrained Moristia similarity index, in PAST program version 3 (http://folk.uio.no/ohammer/ past/). The generated groups are represented with red lines in figure 3. The sedimentation rate of core GeoB 13813-4 was assumed to be constant with a mean value of 1.3 cm yr-1 (Table 1; Perez Becoña, 2014), while for the sedimentation rate of core BAR1 three groups were observed: 1911-1973; 1976-1984 and 1986-2010. The mean sedimentation rate for the above groups showed an increasing trend from 0.24 ± 0.13 cm yr-1 to 0.31 ± 0.14 cm yr-1 and 0.37 ± 0.10 cm yr-1, respectively. The most positive and stable values of SOI (La Niña events) were recorded during 1910-1970. After 1970, a higher variability and a trend towards more negative values was observed (El Niño events). After the year 2005, very negative SOI values occurred (Fig. 4). PDO showed either negative or close to zero values during the early period 1910-1970 (cold phase). During the subsequent interval, i.e., 1970- 2005, positive values (warm phase) were observed. Regarding with AMO, a positive phase was observed from 1925-1960, followed by a negative phase (1960- 2000), but then a shift to a positive phase until the present was observed. The Paraná river discharge anomalies for the years 1910-1970 were mostly associated with negative values (Fig. 4), while between 1970 and 2010 positive anomalies were documented. Between the years 2000 and 2010, we mostly registered values close to zero. Furthermore, the trends in AMO and SOI indices were negatively associated with the anomalies of both Paraná and Uruguay rivers flows, while PDO index were positive associated with such anomalies. A change in mode polarity observed for PDO and AMO took place by the middle 1970s, in addition to more frequent and intense El Niño events that led to the increased rainfall over SESA (Garreaud et al., 2009). Thus, the increase in rainfall over SESA was concomitant with positive anomalies in the Paraná and Uruguay river discharge rates after 1970 (Camilloni, 2005). In this sense, the Paraná river discharge was 20% higher during the past 30 years than the historical average of the 20th century (Mauas et al., 2008). The results of the cluster analyses groups (Fig. 3) showed a differentiation in both sediment cores that correspons to the beginning of the 1970s, which could be associated with the increasing discharge trend recorded for the Parana and Uruguay rivers over the last three decades. The increase in RdlP discharge led to a higher accumulation rate of terrigenous sediments, as inferred from the high sedimentation rate and mean grain size (BAR1), and the lowest Ca/ Ti ratio (GeoB 13813-4), and explains both the spatial and temporal sedimentological and geochemical variability. Ca/Ti ratio in the RdlP was successfully used to infer marine vs. continental influence, as Ti is associated with a continental RdlP discharge, while Ca is associated with autochthonous marine productivity (e.g. foraminifera, Burone et al., 2013). Thus, the highest continental sediment supply to the inner continental shelf is observed in GeoB 13813-4 after 1970, associated with a decrease in the Ca/Ti ratio (Fig. 4). Regarding with Core BAR1 the grainsize distribution and the sedimentation rate were both associated with the estuarine hydrodynamic changes. After 1970, the highest and most variable sedimentation rate and mean grain size was found, probably associated to an increase in both the Paraná and Uruguay river discharges during the past three decades, while the lowest and more stable sedimentation rates and mean sediment grain size recorded before 1970, is indicating a reduced RdlP freshwater supply to the study area. This study shows that both sediment cores contain a distinct continental runoff record as the result of climatic changes (PDO, AMO and ENOS), which have influenced the precipitation patterns over SESA. Both sites reflect similar responses to these environmental changes for the last 100 yr in continental terrigenous sediment supply from the RdlP watershed towards the inner continental shelf. We conclude that it is possible to assess the temporal? RdlP discharge patterns variability within the estuarine and adjacent oceanic area through the study of terrigenous proxies from sediment cores retrieved within the continental shelf.

El Río de la Plata (RdlP) presenta significativas variaciones naturales (hidrodinámicas y oceanográficas) asociadas a diferentes condiciones climáticas. El propósito de este trabajo es inferir los cambios de aportes continentales de sedimentos y su relación con las variaciones hidrológicas del Río de la Plata, a través del análisis de proxies sedimentológicos y geoquímicos en testigos de sedimentos de la plataforma interna uruguaya que registran los últimos 100 años, aproximadamente. A partir de la datación por 210Pb de dos testigos de sedimentos (GeoB 13813-4 y BAR1) se reconstruyó la geocronología del ambiente, y se relacionó con datos de las forzantes climáticas Pacific Decadal Oscillation, El Niño/La Niña Southern Oscillation, Atlantic Multidecadal Oscillation, y las anomalías hidrológicas de los ríos Paraná y Uruguay. Los valores más positivos y estables del Southern Oscillation Index, los cuales corresponden a fases La Niña, se observan en el periodo correspondiente entre 1910-1970, respecto al resto de la serie, donde se aprecia una mayor variabilidad y una tendencia hacia valores más negativos (eventos El Niño). Se hicieron dendrogramas (clustering) jerárquicos para ambos testigos. Para el testigo GeoB 13813-4, se utilizó la relación Ca/Ti y la granulometría, mientras que para BAR1 se recurrió a variables granulométricas y la tasa de sedimentación. El mayor aporte continental hacia la región de la plataforma adyacente al Río de la Plata registrado a partir del año 1970, podría ser el factor principal de los agrupamientos observados en los clusters para ambos testigos. Las agrupaciones mostraron una diferenciación en la década de 1970, lo que estaría asociado al aumento de los caudales de los ríos Paraná y Uruguay, durante las últimas tres décadas del siglo XX. Por otra parte se observa que la granulometría del testigo BAR1 presentó un mayor tamaño de grano y más variabilidad que en el caso del testigo GeoB 13813-4. También se determinó una mayor acumulación de sedimentos a través del tiempo en el cinturón de barro del Río de la Plata (plataforma continental adyacente), comparado con aquel registrado en la Barra del Indio (límite entre zona intermedia y externa del estuario). Estas diferencias podrían estar relacionadas con la influencia del Río de la Plata, el cual genera un ambiente altamente dinámico sobre la Barra del Indio y un ambiente más estable sobre el cinturón de barro en la plataforma continental.

Em Roraima, a distribuição espacial das populações indígenas identifica um cenário de busca constante de solos capazes de sustentar uma agricultura itinerante. Este trabalho teve como objetivo estabelecer relação entre a compreensão dos solos por parte dos Yanomami da região do médio Catrimani e o Sistema Brasileiro de Classificação de Solos, bem como avaliar o seu tipo de uso em função de análises químicas para diagnóstico da fertilidade do solo. O trabalho foi executado em duas etapas. A primeira consistiu em visitas a oito malocas para estudar os solos. Foram coletadas amostras em trincheiras até 1,50 m de profundidade para análise e classificação dos solos e (em prospecções com o trado) nas profundidades de 0-10 a 10-30 cm, em 21 tipos de uso agrícola, e da área de floresta para análises químicas de fertilidade. A segunda fase foi uma oficina, abordando os sistemas de exploração agrícola, com duração de 20 h. Focalizou-se a discussão sobre a compreensão do meio ambiente (Urihi)(1) e sistemas de produção agrícolas e sobre a importância do uso correto do conhecimento dos solos. Os solos são denominados pelos Yanomami em função das características morfológicas, pelos teores de matéria orgânica e pela presença de minhocas, e da posição na paisagem - a escolha para agricultura é fundamentada nessas características. As práticas agrícolas consistem da derrubada da mata nativa, queima e plantio das culturas em separado. Os solos descritos na área foram: Argissolo Vermelho-Amarelo (Maxita a uuxi wakë axi), Argissolo Amarelo (Maxita a axi), Latossolo Amarelo (Maxita a axi) e Plintossolo (Maxita a axi a maamaxipë). O processo de derruba e queima promove um incremento inicial do teor de Ca e K trocáveis e P assimilável devido à contribuição das cinzas, o que permite a exploração das áreas por um período máximo de três anos.

In Roraima, the spatial distribution of indigenous peoples indicates a background of constant search for soils capable of sustaining shift cultivation. This study aimed to establish a relationship between the understanding of soil by the Yanomami tribe from the mid-Catrimani river region and the Brazilian System of Soil Classification and evaluate the type of agricultural land use according to soil fertility tests, in two steps. The first consisted of visiting eight Indian communities to collect soil samples at 21 sites with different types of agriculture and forests, both from profile soil (depth 0-1.50 m) and pits (depth 0-0.1 m and 0.1-0.3 m) for laboratory analysis. The second step was a workshop addressing the shift cultivation systems (duration 20 h). The discussion focused on the understanding of the environment (Urihi) and agricultural production systems, and on the importance of the correct use of knowledge of the soil and its fertility. Soils are named according to their morphology and position in the landscape by the Yanomami. The choice of agricultural areas is based on these features, aside from the organic matter content and the presence of earthworms. Agricultural practices comprise clearing and burning of the native forest immediately before planting a set of separate crops. The soils described in the area were classified according to the Brazilian taxonomic system as follows: Red Yellow Argisol (Maxita a uuxi wake axi), Yellow Argisol (Maxita a axi) Yellow Latosol (Maxita a axi) and Plintosol (Maxita a axi a maaxipé). Slashing and burning initially increases exchangeable Ca, K and available P due to the contribution of the ashes, which allows an agricultural exploitation of these areas for a maximum period of three years.

Muitos comentaristas realçam a fertilidade da Terra Preta de Índio (TPI), enfatizando seu potencial para uma agricultura sustentável. Alguns estudiosos acreditam que Terra Mulata (uma forma menos fértil, porém mais comum de TPI) foi criada por meio de práticas agrícolas usadas por grandes populações sedentárias na época pré-colombiana. Mas o que estes agricultores ameríndios cultivavam? Até recentemente, o consenso acadêmico era de que mandioca não se adaptava bem em TPI. Novas pesquisas no Médio Rio Madeira estão demostrando, porém, que este consenso era prematuro. Nesta região, a colheita mais comum em roças de TPI é mandioca amarga. Os agricultores têm diversas variedades crioulas (raças primitivas) de mandioca, que eles acreditam render especialmente bem em TPI e, logicamente, plantam mais destas variedades em TPI. Aspectos do comportamento e da percepção do cultivo de mandioca entre 52 agricultores da comunidade de Barro Alto foram observados quantitativamente em quatro tipos de solo da terra firme (Terra Preta, Terra Mulata, Latossolos e Argissolos). Esses agricultores plantam diferentes configurações de raças primitivas em diferentes ecótonos, de acordo com a percepção deles sobre o comportamento de cada raça primitiva e suas características em cada tipo de solo e situação da sucessão ecológica. Estas práticas, por sua vez, influenciam as pressões seletivas nessas raças, pois é mais provável que o material genético novo incorporado de mudas espontâneas contenha características presentes nas raças prevalentes em cada tipo de solo. Devido à pressão da população em Barro Alto, a mandioca é cultivada em sistemas mais intensivos, com períodos mais curtos entre plantio e colheita (5-10 meses) e períodos menores de pousio (1-2 anos). A conseqüência desses processos é uma dinâmica co-evolutiva em TPI, diferentemente de solos não-antrópicos. Mais estudos antropológicos do cultivo de mandioca em um dos ambientes agrícolas mais ricos da Amazônia podem encher essa lacuna na literatura, abrindo uma janela adicional sobre o período pré-colombiano.

Many commentators highlight the fertility of Anthropogenic Dark Earths (ADE), emphasizing their potential for sustainable agriculture. Some scholars believe that terra mulata (the less fertile, more extensive form of ADE) was created by means of agricultural practices used by large settled populations of pre-Columbian farmers. But what was it that these Amerindian farmers were growing? Until recently, scholarly consensus held that manioc does not perform well on ADE. New research on the middle Madeira River is showing, however, that this consensus was premature. In this region, the most common crop in ADE fields is bitter manioc. Farmers there have various landraces of manioc that they believe yield particularly well on ADE, and logically plant more of these varieties on ADE. Aspects of the behaviour and perception of manioc cultivation among 52 farmers at the community of Barro Alto were measured quantitatively on four terra firme soil types (Terra Preta, Terra Mulata, Oxisols and Ultisols). These farmers plant different configurations of landraces in different soils, according to their perception of the suitability of particular landraces and their characteristics to certain soil types and successional processes. This, in turn, shapes selective pressures on these varieties, as new genetic material incorporated from volunteer seedlings is more likely to contain traits present in the most prevalent landrace(s) in each soil type. Owing to localized population pressure at Barro Alto, manioc is under more intensive cultivation systems, with shorter cropping periods (5-10 months) and shorter fallow periods (1-2 years). The outcome of these processes is different co-evolutionary dynamics on ADE as opposed to non-anthropogenic soils. Further anthropological study of manioc swiddening in one of the richest agricultural environments in Amazonia can fill a gap in the literature, thus opening an additional window on the pre-Columbian period.

The present study discusses the results of 20 years (1975-1995) of chemical analysis of waters of the Elqui river and its tributaries, performed by the Dirección General de Aguas - the national waters authority. This discussion is complemented with the results of recent studies of the geochemistry of the sediment of its basin. Among the principal conclusions attained, are the high contents of Cu and As of the Toro, Turbio and Elqui rivers, that receive a direct (Toro river) or indirect contribution of the Malo river, which drains the hydrothermal alteration zone of the Au-Cu-As deposits of the El Indio mining district. The growing intensification of the mining and metallurgical activities at El Indio coincided with increasing contents of Cu and As in the Toro, Turbio and Elqui rivers, though they are progressively attenuated for As due to the diluent effects of low-mineralized tributary river waters. On the other hand, the Elqui river has received significant amounts of Cu from the Talcuna mining district in the Quebrada Marquesa ravine. Though the mining activities at El Indio probably contributed to the increase in As, Cu and Fe contents of the waters, these and other heavy metals have been present in the acid drainage water of the Malo river long before the beginning of said activities. Likewise, the Malo river will continue to be a pollution source after the closure - already completed -of the El Indio mining district.

El presente trabajo expone y discute los resultados de veinte años (1975-1995) de análisis de aguas del Río Elqui y sus tributarios, realizados por la Dirección General de Aguas. Su discusión se complementa con la de resultados de estudios recientes de la geoquímica de los sedimentos de la misma cuenca. Entre sus principales conclusiones destaca la alta concentración de Cu y As de los ríos Toro, Turbio y Elqui, que reciben el aporte directo (Río Toro) o indirecto de las aguas del Río Malo, que drena la zona de alteraciones hidrotermales y mineralizaciones de Au-Cu-As del distrito minero de El Indio. La intensificación de las faenas minero-metalúrgicas de El Indio coincidió con incrementos en los contenidos de As y Cu de los ríos Toro, Turbio y Elqui, aunque los de As son progresivamente atenuados por el efecto de dilución debido al aporte de ríos tributarios pobres en ese elemento. Por otra parte, el Río Elqui ha recibido aportes significativos de Cu provenientes del distrito minero de Talcuna, situado en la Quebrada Marquesa. Aunque las actividades mineras de El Indio contribuyeron probablemente a aumentar el contenido de As, Cu y Fe de las aguas, estos y otros metales pesados han estado presentes en las aguas afectadas por drenaje ácido del Río Malo desde mucho tiempo antes de que dichas actividades se iniciaran. Igualmente, el Río Malo continuará siendo una fuente contaminante después del cierre - ya completado - del distrito minero de El Indio.

La distribución espacial de comunidades de pastos marinos y algas puede ser difícil de determinar en sistema lagunares grandes y someros donde la alta turbidez no permite el uso de métodos ópticos,como fotografías aéreas e imágenes satelitales. Complicaciones adicionales pueden surgir cuando las algas no están adheridas permanentemente al sustrato y derivan con las mareas y corrientes.Se realizó un estudio utilizando discriminación acústica del fondo marino en el Indian River Lagoon (Florida,EUA) para determinar la cantidad de algas y pastos que derivan. Se realizaron sondeos acústicos en el Sebastian Inlet con el sistema QTC View V y transductores de 50 y 200 kHz.Las áreas de pastos marinos pudieron ser identificadas,y están mezcladas con una gran cantidad de algas a la deriva.Se rellenó los espacios sin datos con extrapolaciones basadas en la técnica del "vecino más cercano ",produciendo un mapa espacialmente coherente.Comprobaciones de campo con video y "matrices de confusión "indican que los mapas tienen un alto nivel de concordancia (60%)con la distribución real de las algas;sin embargo,hubo cierta confusión entre arena y algas,y entre arena y pastos marinos.

The spatial distribution of seagrass and algae communities can be difficult to determine in large,shallow lagoon systems where high turbidity prevents the use of optical methods like aerial photography or satellite imagery.Further complications can arise when algae are not permanently attached to the substratum and drift with tides and currents.A study using acoustic seafloor discrimination was conducted in the Indian River Lagoon (Florida,USA)to determine the extent of drift algae and seagrass.Acoustic surveys using the QTC View V system based on 50 and 200 kHz transducers were conducted near Sebastian Inlet.Results indicate that areas of seagrass can be identified,and are mixed with a high abundance of drift algae.Nearest-neighbor extrapolation was used to fill in spaces between survey lines and thus obtain spatially cohesive maps.These maps were then ground-truthed using data from towed video and compared using confusion matrices.The maps showed a high level of agreement (60%)with the actual distribution of algae,however some confusion existed between bare sand and algae as well as seagrass.