Further Studies on the Physical and Biogeochemical Causes for Large Interannual Changes in the Patagonian Shelf Spring-Summer Phytoplankton Bloom Biomass

A very strong and persistent phytoplankton bloom was observed by ocean color satellites during September - December 2003 along the northern Patagonian shelf. The 2003 bloom had the highest extent and chlorophyll a (Chl-a) concentrations of the entire Sea-viewing Wide Field-of-view Sensor (SeaWiFS) period (1997 to present). SeaWiFS-derived Chl-a exceeded 20 mg/cu m in November at the bloom center. The bloom was most extensive in December when it spanned more than 300 km across the shelf and nearly 900 km north-south (35degS to 43degS). The northward reach and the deep penetration on the shelf of the 2003 bloom were quite anomalous when compared with other years, which showed the bloom more confined to the Patagonian shelf break (PSB). The PSB bloom is a conspicuous austral spring-summer feature detected by ocean color satellites and its timing can be explained using the Sverdrup critical depth theory. Based on high-resolution numerical simulations, in situ and remote sensing data, we provide some suggestions for the probable mechanisms responsible for that large interannual change of biomass as seen by ocean color satellites. Potential sources of macro and micro (e.g., Fe) nutrients that sustain the high phytoplankton productivity of the Patagonian shelf waters are identified, and the most likely physical processes that maintain the nutrient balance in the region are discussed

Solar and climate signal records in tree ring width from Chile (AD 1587-1994)

Abstract Tree growth rings represent an important natural record of past climate variations and solar activity effects registered on them. We performed in this study a wavelet analysis of tree ring samples of Pilgerodendron cupressoides species, from Glaciar Pio XI (Lat: 49112 0 S; 74155 0 W; Alt: 25 m), Chile. We obtained an average chronology of about 400 years from these trees. The 11-yr solar cycle was present during the whole period in tree ring data, being more intense during Maunder minimum (1645-1715). The short-term periods, around 2-7 yr, that were found are more likely associated with ENSO effects. Further, we found significant periods around 52 and 80-100 yr. These periodicities are coincident with the fourth harmonic (52 yr) of the Suess cycle (208 yr) and Gleissberg ($80-100 yr) solar cycles. Therefore, the present analysis shows evidence of solar activity effect/modulation on climatic conditions that affect tree ring growth. Although we cannot say with the present analysis if this effect is on local, regional or global climate, these results add evidence to an important role of solar activity over terrestrial climate over the past$400 yr.

Probiotics mitigate thermal stress- and pathogen-driven impacts on coral skeleton

Threats leading to a reduction in coral populations are apparent worldwide. Several different approaches have been tested to accelerate the adaptation of corals to a changing climate. Here, we evaluated the skeleton structure, crystal habit, and chemical changes of the coral Pocillopora damicornis in response to the pathogen (Vibrio coralliilyticus) and probiotic (Beneficial Microorganisms for Corals, BMCs) inoculation under ambient conditions (26 °C) and thermal stress (30 °C) during a 50-day mesocosm experiment. The skeletons were analyzed using microtomography, energy-dispersive x-ray spectroscopy (EDX/SEM), and densitometry to investigate the skeleto-physico-chemical micro-morphological changes in porosity, median pore-size diameter, crystal habit, Mg/Ca, Sr/Ca, the skeleton mineral density (g/cm2) and skeleton mineral content (g–2). The results indicate considerable changes in the coral skeleton caused by both temperature and microbial inoculation. Most importantly, lower density (to ∼ x̄ 0.5 g/cm2) and higher porosity (up to ∼ x̄ 47%) were correlated with inoculation of V. coralliilyticus and mitigated by probiotics. BMCs also substantially increased calcification, as evidenced by Mg/Ca in the skeleton of thermally stressed corals. At the micron scale, aragonite crystal fibbers precipitated during the experiments showed an acicular habit in thermally stressed and pathogen-inoculated corals kept at 30 °C. In contrast, a spherulitic habit, characteristic of high growth rates, was observed in corals inoculated with both BMCs and V. coralliilyticus. Our findings reveal that pathogen inoculation and thermal stress had notable impacts on coral skeleton properties, including porosity, density, and crystal morphology, in a short period of time, which highlights the potential impacts of shifts in climate warming and environmental quality. Interestingly, BMCs played a role in maintaining the properties of skeleton calcification

TENDÊNCIAS HISTÓRICAS DAS TAXAS DE SEDIMENTAÇÃO E ACÚMULO DE ELEMENTOS TRAÇO NO BAIXO CURSO DO RIO DOCE, ESPÍRITO SANTO, BRASIL

A bacia hidrográfica do rio Doce apresenta uma história de intensa ocupação humana e variedade de atividades econômicas e conseqüente poluição química. Este trabalho tem como objetivo determinar a concentração de elementos traço em sedimentos (Cu, Zn, Cr, Pb, Fe, Mn e Ni) no baixo curso da bacia do Rio Doce. Foram coletados três testemunhos sedimentares em diferentes pontos da bacia: um à montante, na frente e outro à jusante da cidade de Linhares. As taxas de sedimentação entre 0,12 e 2,87 cm ano-1 foram definidas pelo método baseado em 210Pb. Picos de concentração de elementos traço foram determinados no testemunho A (1970 e 2010). No testemunho B, foram determinados para as décadas de 1930, 1990 e 2000. As maiores concentrações médias de elementos traço foram determinados no ponto C. As concentrações de elementos traço apresentam-se em conformidade com fatos históricos registrados na bacia do Rio Doce como um todo

Projeto PortVix: a fala de Vitória/ES em cena

Os objetivos centrais do presente artigo são (1) apresentar à comunidade científica o projeto PortVix, que trata da fala da cidade de Vitória, capital do Espírito Santo; (2) sintetizar os trabalhos desenvolvidos e em desenvolvimento, com base nos dados deste projeto; e (3) tecer considerações sobre o alinhamento da fala de Vitória ao cenário nacional e sobre traços que a caracterizam. A Teoria da Variação e de Mudança Linguística norteia a organização da amostra e, de forma geral, a análise de diversos fenômenos variáveis, a saber, alternância entre futuro do pretérito e pretérito imperfeito; a expressão variável do futuro do presente; usos do gerúndio; variação sintática das orações adverbiais finais; alternância nós/a gente; a expressão do objeto direto anafórico; concordância nominal; concordância verbal; expressão gramatical do imperativo; alternância indicativo/subjuntivo; alternância você/cê/ocê; ausência/presença de artigo diante de antropônimos e de possessivos. Observações do senso comum e resultados das análises permitem evidenciar que, ao lado de aspectos que alinham a fala de Vitória-ES ao cenário nacional, corroborando a generalidade de diversos fenômenos, há outros aspectos que permitem inferir a caracterização da fala capixaba face aos três estados com os quais o Espírito Santo estabelece fronteiras: Rio de Janeiro, Bahia e, especialmente, Minas Gerais

Atmospheric air pressure from Central-western Antarctica at Criosfera1 remote laboratory

The meteorological database provided herein derives from the Criosphere 1 remote laboratory. It is the result of a scientific consortium among Rio de Janeiro State University - UERJ, UFRGS and INPE and is the first research module of Brazil to operate autonomously and remotely in Central western Antarctica. In its present configuration, the Criosfera 1 hosts experiments aimed at studying atmospheric chemistry, meteorology and its relationship to the Antarctic ice sheet

Atmospheric air temperature from Central-western Antarctica at Criosfera1 remote laboratory

Meteorological database provided herein derives from the Criosphere 1 remote laboratory. It is the result of a scientific consortium among Rio de Janeiro State University - UERJ, UFRGS and INPE and is the first research module of Brazil to operate autonomously and remotely in Central western Antarctica. In its present configuration, the Criosfera 1 hosts experiments aimed at studying atmospheric chemistry, meteorology and its relationship to the Antarctic ice sheet

Amazonian biomass burning enhances tropical Andean glaciers melting

International audienceThe melting of tropical glaciers provides water resources to millions of people, involving social, ecological and economic demands. At present, these water reservoirs are threatened by the accelerating rates of mass loss associated with modern climate changes related to greenhouse gas emissions and ultimately land use/cover change. Until now, the effects of land use/cover change on the tropical Andean glaciers of South America through biomass burning activities have not been investigated. In this study, we quantitatively examine the hypothesis that regional land use/cover change is a contributor to the observed glacier mass loss, taking into account the role of Amazonian biomass burning. We demonstrated here, for the first time, that for tropical Andean glaciers, a massive contribution of black carbon emitted from biomass burning in the Amazon Basin does exist. This is favorable due to its positioning with respect to Amazon Basin fire hot spots and the predominant wind direction during the transition from the dry to wet seasons (Aug-Sep-Oct), when most fire events occur. We investigated changes in Bolivian Zongo Glacier albedo due to impurities on snow, including black carbon surface deposition and its potential for increasing annual glacier melting. We showed that the magnitude of the impact of Amazonian biomass burning depends on the dust content in snow. When high concentration of dust is present (e.g. 100 ppm of dust), the dust absorbs most of the radiation that otherwise would be absorbed by the BC. Our estimations point to a melting factor of 3.3 ± 0.8% for black carbon, and 5.0 ± 1.0% for black carbon in the presence of low dust content (e.g. 10 ppm of dust). For the 2010 hydrological year, we reported an increase in runoff corresponding to 4.5% of the annual discharge during the seasonal peak fire season, which is consistent with our predictions

South Tropical Atlantic anti-phase response to Holocene Bond Events

Erreur d'affiliation pour M. BOUSSAFIR qui est affecté à l'Institut des Sciences de la Terre d'Orléans - UMR 7327International audienceRecords of the climatic impacts of the North Atlantic Bond cycles over the subtropical Southern Hemisphere re-main scarce, and their mechanism is a topic of active discussion. We present here an alkenone-based reconstruct-ed sea surface temperature (SST) of a sediment core retrieved from the Brazilian Southwestern Tropical Atlantic (SWTA), Rio de Janeiro, together with a sediment SST record from the Cariaco Basin. The sediment cores span the period 2,100 B.P. – 11,100 B.P. Morlet-wavelet analysis detected marked periodic signals of ~ 0.8, ~ 1.7 and ~2.2 kyr, very similar and with comparable phases to the hematite-stained-grain time series from the Northern North Atlantic in which the cyclic pattern was recognized as Bond cycles. Our result corroborates the modeled surface ocean anti-phase thermal relation between the North and the South Atlantic. We attribute this behavior to the slowing of the Atlantic Meridional Overturning Circulation. The relative SST warming at Rio de Janeiro and the relative cooling at Cariaco were comparatively more pronounced during the early Holocene (from 11 to 5 kyr B.P.) than in more recent time

South Tropical Atlantic anti-phase response to Holocene Bond Events

Erreur d'affiliation pour M. BOUSSAFIR qui est affecté à l'Institut des Sciences de la Terre d'Orléans - UMR 7327International audienceRecords of the climatic impacts of the North Atlantic Bond cycles over the subtropical Southern Hemisphere re-main scarce, and their mechanism is a topic of active discussion. We present here an alkenone-based reconstruct-ed sea surface temperature (SST) of a sediment core retrieved from the Brazilian Southwestern Tropical Atlantic (SWTA), Rio de Janeiro, together with a sediment SST record from the Cariaco Basin. The sediment cores span the period 2,100 B.P. – 11,100 B.P. Morlet-wavelet analysis detected marked periodic signals of ~ 0.8, ~ 1.7 and ~2.2 kyr, very similar and with comparable phases to the hematite-stained-grain time series from the Northern North Atlantic in which the cyclic pattern was recognized as Bond cycles. Our result corroborates the modeled surface ocean anti-phase thermal relation between the North and the South Atlantic. We attribute this behavior to the slowing of the Atlantic Meridional Overturning Circulation. The relative SST warming at Rio de Janeiro and the relative cooling at Cariaco were comparatively more pronounced during the early Holocene (from 11 to 5 kyr B.P.) than in more recent time