Abrupt wind regime changes in the North Atlantic Ocean during the past 30,000-60,000 years

The inputs of higher plants in Blake Outer Ridge (subtropical western North Atlantic) during marine isotope stage 3 (MIS3) have been recorded at high resolution by quantification of C23–C33 odd carbon numbered n-alkanes and C20–C30 even carbon numbered n-alkan-1-ols in sediment sections of Ocean Drilling Program Site 1060. The changes of these proxies at this open marine site are mainly related to eolian inputs. Their concentrations and fluxes exhibit major abrupt variations that are correlated with Dansgaard/Oeschger (D/O) patterns in Greenland ice cores. The ratios between interstadials and stadials range between 2 and 9 times. The intense flux increases in the D/O stadials are linked to strong enhancements of the westerly wind regime at these subtropical latitudes during stadials. The observed variation was paralleled by changes in wind-blown dust and the polar circulation index in Greenland ice, which is in agreement with previously hypothesized atmospheric teleconnections between northern and middle-low latitudes of the Northern Hemisphere. The close correspondence between sedimentary and ice core proxies is evidence that crossings of the glacial climate thresholds involved major reorganizations of the troposphere. The observed large rise in higher plant biomarkers indicates that climate stabilization in the D/O stadial conditions led to main increases in wind intensity

Meconio y exposición prenatal a neurotóxicos

6 pages, 1 figures, 2 tables.[ESP] Introducción. La ubicuidad con la que se encuentran la mayoría de las substancias neurotóxicas en el medio ambiente implica a los pediatras en la necesidad de desarrollar métodos para medir la magnitud de la exposición durante los periodos vulnerables del desarrollo. Una forma útil de abordar este problema consiste en analizar muestras biológicas que acumulen las substancias neurotóxicas o sus metabolitos durante el periodo fetal.Método. Revisión bibliográfica sistemática de los últimos 20 años obtenida principalmente de Medline; Science Citation Index y Embase sobre los estudios con meconio como matriz de exposición prenatal a substancias neurotóxicas. El perfil de búsqueda utilizado fue: meconium, prenatal exposure, biological markers, matrices, environmental pollutants, nervous system poisonings, neurotoxicity sindromes. Hemos seleccionado los trabajos más importantes y de sus referencias se han obtenido los más relevantes de los años previos a la búsqueda.Resultados. Tradicionalmente, los esfuerzos para determinar la exposición fetal se han centrado en el análisis de sangre de cordón u orina de la madre o el neonato. El meconio es fácilmente disponible, es inerte, acumula los neurotóxicos y/o sus metabolitos desde la semana 12 de gestación donde quedan “fosilizados” hasta el nacimiento. Puede constituir un instrumento muy importante para investigar la exposición fetal a los distintos contaminantes ambientales y en particular a neurotóxicos.Conclusiones. Las exposiciones fetales a los distintos neurotóxicos estudiados a través de sangre materna, de cordón, pelo, uña, placenta y orina parecen ser menos predictivas sobre los efectos neurológicos que las mediciones de los mismos realizadas en meconio. Son necesarios más estudios en este campo.Implementar y desarrollar la medida en meconio de una amplia gama de sustancias neurotóxicas ayudará en la práctica pediátrica a una intervención e identificación temprana mostrando las exposiciones que puedan provocar daño y facilitando el desarrollo de medidas preventivas y rehabilitadoras.[ENG] Brackground. The environmental ubiquity of most neurotoxicants implies the pediatricians in the development of methods for exposure measurement during the vulnerable periods of development. The analysis of biological samples able to accumulate the neurotoxicant substances or its metabolites during the fetal period is a useful approach to fulfil this objective.Material and methods. A systematic literature review of the last 20 years in Medline, Science Citation Index and Embase on the studies with meconium like womb of prenatal exposure to neurotoxicants has been undertaken. The search profile was: “meconium”, “prenatal exposure”, “biological markers”, “matrices”, “environmental pollutants”, “nervous system poisonings”, “neurotoxicity sindromes”. We selected the most relevant articles and retrieved more from their references.Results. Traditionally, the efforts to determine the fetal exposure have been centered in the analysis of cord blood, urinates of the mother or of the neonato. Meconium is easily available, inert, accumulates the neurotoxicants and/or its metabolitos from week 12 of gestation where they are "fossilized" until the birth. It can constitute a very important instrument for the investigation of the fetal exposure to the different environmental pollutants and in particular to neurotoxicants.Conclusions. Foetal exposure to different neurotoxicants monitored from maternal blood, cord blood, hair, fingernail, placenta and urinates seem to be less predictive for neurological effects than meconium. However, more studies are needed to confirm this hypothesis.Implementation and measurement in meconium of a wide range of neurotoxic substances will be of help in the pediatric practice for intervention and early identification as it will reveal harmful exposures and facilitate the implementation of preventive measures.Los autores quieren expresar su agradecimiento a los miembros de la red de Investigación Colaborativa INMA, y en especial a Amparo Quiles Latorre, Elena Romero Aliaga y Sandra Pérez Aliaga, por su apoyo y colaboración en la realización del trabajo de campo; al equipo de enfermería de la 7ª, 8ª y 9ª de la maternidad del Hospital Materno-Infantil Universitario La Fe y a los recién nacidos y sus felices padres que con su colaboración y entusiasmo hacen posible llevar a término estos estudios.Peer reviewe

Effects of pre and postnatal exposure to low levels of polybromodiphenyl ethers on neurodevelopment and thyroid hormone levels at 4years of age

There are at present very few studies of the effects of polybromodiphenyl ethers (PBDEs), used as flame retardants in consumer products, on neurodevelopment or thyroid hormone levels in humans. The present study aims to examine the association between pre and postnatal PBDE concentrations and neurodevelopment and thyroid hormone levels in children at age 4. years and isolate the effects of PBDEs from those of PCBs, DDT, DDE and HCB.A prospective birth cohort in Menorca (Spain) enrolled 482 pregnant mothers between 1997 and 1998. At 4. years, children were assessed for motor and cognitive function (McCarthy Scales of Children's Abilities), attention-deficit, hyperactivity and impulsivity (ADHD-DSM-IV) and social competence (California Preschool Social Competence Scale). PBDE concentrations were measured in cord blood (N = 88) and in serum of 4. years olds (N = 244). Among all congeners analyzed only PBDE 47 was quantified in a reasonable number of samples (LOQ = 0.002. ng/ml). Exposure to PBDE 47 was analyzed as a dichotomous variable: concentrations above the LOQ (exposed) and concentrations below (referents).Scores for cognitive and motor functions were always lower in children pre and postnatally exposed to PBDE47 than in referents, but none of these associations was statistically significant (β coefficient (95%CI) of the total cognition score: -2.7 (-7.0, 1.6) for postnatal exposure, and -1.4 (-9.2, 6.5) for prenatal exposure). Postnatal exposure to PBDE 47 was statistically significantly related to an increased risk of symptoms on the attention deficit subscale of ADHD symptoms (RR (95%CI) = 1.8 (1.0, 3.2)) but not to hyperactivity symptoms. A statistically significant higher risk of poor social competence symptoms was observed as a consequence of postnatal PBDE 47 exposure (RR (95%CI) = 2.6 (1.2, 5.9)). Adjustment for other organochlorine compounds did not influence the results. Levels of thyroid hormones were not associated to PBDE exposure.This study highlights the importance of assessing the effects of PBDE exposure not just prenatally but also during the early years of life. In the light of current evidence a precautionary approach towards PBDE exposure of both mothers and children seems warranted. © 2010 Elsevier Ltd

Variations in mid-latitude North Atlantic surface water properties during the mid-Brunhes (MIS 9–14) and their implications for the thermohaline circulation

© The Authors, 2010. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Climate of the Past 6 (2010): 531-552, doi:10.5194/cp-6-531-2010.Stable isotope and ice-rafted debris records from three core sites in the mid-latitude North Atlantic (IODP Site U1313, MD01-2446, MD03-2699) are combined with records of ODP Sites 1056/1058 and 980 to reconstruct hydrographic conditions during the middle Pleistocene spanning Marine Isotope Stages (MIS) 9–14 (300–540 ka). Core MD03-2699 is the first high-resolution mid-Brunhes record from the North Atlantic's eastern boundary upwelling system covering the complete MIS 11c interval and MIS 13. The array of sites reflect western and eastern basin boundary current as well as north to south transect sampling of subpolar and transitional water masses and allow the reconstruction of transport pathways in the upper limb of the North Atlantic's circulation. Hydrographic conditions in the surface and deep ocean during peak interglacial MIS 9 and 11 were similar among all the sites with relative stable conditions and confirm prolonged warmth during MIS 11c also for the mid-latitudes. Sea surface temperature (SST) reconstructions further reveal that in the mid-latitude North Atlantic MIS 11c is associated with two plateaus, the younger one of which is slightly warmer. Enhanced subsurface northward heat transport in the eastern boundary current system, especially during early MIS 11c, is denoted by the presence of tropical planktic foraminifer species and raises the question how strongly it impacted the Portuguese upwelling system. Deep water ventilation at the onset of MIS 11c significantly preceded surface water ventilation. Although MIS 13 was generally colder and more variable than the younger interglacials the surface water circulation scheme was the same. The greatest differences between the sites existed during the glacial inceptions and glacials. Then a north – south trending hydrographic front separated the nearshore and offshore waters off Portugal. While offshore waters originated from the North Atlantic Current as indicated by the similarities between the records of IODP Site U1313, ODP Site 980 and MD01-2446, nearshore waters as recorded in core MD03-2699 derived from the Azores Current and thus the subtropical gyre. Except for MIS 12, Azores Current influence seems to be related to eastern boundary system dynamics and not to changes in the Atlantic overturning circulation.The Fundacao para a Ciencia e a Tecnologia (FCT) through the PORTO (PDCT/MAR/58282/2004) and SEDPORT projects (PDCTM/ 40017/2003), and postdoctoral (SFRH/BPD/21691/2005) and PhD (SFRH/BP/13749/2003) fellowships funded A. V. and T. R. Additional funding to T. R. and J. G. was provided by the Consolider-Ingenio 2100 Project CE-CSD2007-0067

Human exposure and risk assessment of PAHs bound to three PM fractions (10, 2.5 and 1) in an area influenced by a cement plant

In the present study, we evaluated the concentrations of PAHs in 3 PM fractions (10, 2.5 and 1) collected in the surroundings of a cement plant located in Barcelona. PAH content and speciation were developed for the three fractions to elucidate their distribution among different sizes. Complementarily, the human health risks associated to the PAH exposure were risks by considering the daily activity pattern of an average adult living in of Barcelona (Spain).Financial support was received by the Spanish Ministry of Economy and Competitiveness (MINECO), through the project CTM2012-32778. F. Sánchez-Soberón received a doctoral scholarship as part of the project above mentioned. We also want to thank the European Union Seventh Framework Program for the funding received through the HEALS project (grant agreement No. 603946).Peer reviewe

Millennial-scale vegetation changes in the tropical Andes using ecological grouping and ordination methods

We compare eight pollen records reflecting climatic and environmental change from northern and southern sites in the tropical Andes. Our analysis focuses on the last 30ĝ€ 000 years, with particular emphasis on the Pleistocene to Holocene transition. We explore ecological grouping and downcore ordination results as two approaches for extracting environmental variability from pollen records. We also use the records of aquatic and shoreline vegetation as markers for lake level fluctuations and moisture availability. Our analysis focuses on the signature of millennial-scale climate variability in the tropical Andes, in particular Heinrich stadials (HS) and Greenland interstadials (GI). The pollen records show an overall warming trend during the Pleistocene-Holocene transition, but the onset of post-glacial warming differs in timing among records. We identify rapid responses of the tropical vegetation to millennial-scale climate variability. The signatures of HS and the Younger Dryas are generally recorded as downslope upper forest line (UFL) migrations in our transect, and are likely linked to air temperature cooling. The GI1 signal is overall comparable between northern and southern records and indicates upslope UFL migrations and warming in the tropical Andes. Our marker for lake level changes indicated a north-To-south difference that could be related to moisture availability. The air temperature signature recorded by the Andean vegetation was consistent with millennial-scale cryosphere and sea surface temperature changes but suggests a potential difference between the magnitude of temperature change in the ocean and the atmosphere. We also show that arboreal pollen percentage (AP %) and detrended correspondence analysis (DCA) scores are two complementary approaches to extract environmental variability from pollen records

Land-ocean changes on orbital and millennial time scales and the penultimate glaciation

Past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change. However, beyond the last glacial, an integrated view of orbital- and millennial-scale changes and their relation to the record of glaciation has been lacking. Here, we present a detailed record of variations in the land-ocean system from the Portuguese margin during the penultimate glacial and place it within the framework of ice-volume changes, with particular reference to European ice-sheet dynamics. The interaction of orbital- and millennial-scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations, a transitional mid-part, and a late part with more subdued changes as the system entered a maximum glacial state. The most extreme event occurred in the mid-part and was associated with melting of the extensive European ice sheet and maximum discharge from the Fleuve Manche river. This led to disruption of the meridional overturning circulation, but not a major activation of the bipolar seesaw. In addition to stadial duration, magnitude of freshwater forcing, and background climate, the evidence also points to the influence of the location of freshwater discharges on the extent of interhemispheric heat transport

Traffic-related air pollution, APOE ∊4 status, and neurodevelopmental outcomes among school children enrolled in the BREATHE project (Catalonia, spain)

BACKGROUND: Traffic-related air pollution is emerging as a risk factor for Alzheimer's disease (AD) and impaired brain development. Individual differences in vulnerability to air pollution may involve the e4 allele of Apolipoprotein E (APOE) gene, the primary genetic risk factor for AD. OBJECTIVE: We analyzed whether the association between traffic air pollution and neurodevelopmental outcomes is modified by APOE e4 status in children. METHODS: Data on parent-reported behavior problems (total difficulties scores, Strengths and Difficulties Questionnaire), teacher-reported attention-deficit hyperactivity disorder (ADHD) symptom scores, cognitive performance trajectories (computerized tests of inattentiveness and working memory repeated 2–4 times during January 2012–March 2013), and APOE genotypes were obtained for 1,667 children age 7–11 y attending 39 schools in or near Barcelona. Basal ganglia volume (putamen, caudate, and globus pallidum) was measured in 163 of the children by MRI (October 2012–April 2014.) Average annual outdoor polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and nitrogen dioxide (NO ) concentrations were estimated based on measurements at each school (two 1-wk campaigns conducted 6 months apart in 2012). RESULTS: APOE e4 allele carriers had significantly higher behavior problem scores than noncarriers, and adverse associations with PAHs and NO were stronger or limited to e4 carriers for behavior problem scores (P-interaction 0.03 and 0.04), caudate volume (P-interaction 0.04 and 0.03), and inattentiveness trajectories (P-interaction 0.15 and 0.08, respectively). Patterns of associations with the same outcomes were similar for EC. CONCLUSION: PAHs, EC, and NO were associated with higher behavior problem scores, smaller reductions in inattentiveness over time, and smaller caudate volume in APOE e4 allele carriers in our study population, and corresponding associations were weak or absent among e4 noncarriers. These findings support a potential role of APOE in biological mechanisms that may contribute to associations between air pollution and neurobehavioral outcomes in children

Mediterranean circulation perturbations over the last five centuries: Relevance to past Eastern Mediterranean Transient-type events

The Eastern Mediterranean Transient (EMT) occurred in the Aegean Sea from 1988 to 1995 and is the most significant intermediate-to-deep Mediterranean overturning perturbation reported by instrumental records. The EMT was likely caused by accumulation of high salinity waters in the Levantine and enhanced heat loss in the Aegean Sea, coupled with surface water freshening in the Sicily Channel. It is still unknown whether similar transients occurred in the past and, if so, what their forcing processes were. In this study, sediments from the Sicily Channel document surface water freshening (SCFR) at 1910 ± 12, 1812 ± 18, 1725 ± 25 and 1580 ± 30 CE. A regional ocean hindcast links SCFR to enhanced deep-water production and in turn to strengthened Mediterranean thermohaline circulation. Independent evidence collected in the Aegean Sea supports this reconstruction, showing that enhanced bottom water ventilation in the Eastern Mediterranean was associated with each SCFR event. Comparison between the records and multi-decadal atmospheric circulation patterns and climatic external forcings indicates that Mediterranean circulation destabilisation occurs during positive North Atlantic Oscillation (NAO) and negative Atlantic Multidecadal Oscillation (AMO) phases, reduced solar activity and strong tropical volcanic eruptions. They may have recurrently produced favourable deep-water formation conditions, both increasing salinity and reducing temperature on multi-decadal time scales