Biogeochemical controls of the transport and cycling of persistent organic pollutants in the polar oceans

Humanity is currently using more than 200000 synthetic organic compounds in many industrial, agricultural and domestic applications. Many of these chemicals reach the environment and have a harmful effect on ecosystems and humans. Among them, the group of persistent organic pollutants (POPs) comprises several families of compounds that have physical and chemical properties that give them the ability to be distributed and impact globally (semivolatility, high persistence and bioaccumulation capacity due to their hydrophobicity). In the present thesis, the coupling of atmospheric transport and biogeochemical cycles in the Arctic and Southern Ocean has been studied for Hexachlorocyclohexanes (HCHs), Hexachlorobenzene (HCB) and Polychlorinated Biphenyls (PCBs). Three oceanographic cruises were conducted, one in the North Atlantic and the Arctic Ocean (2007) and two in the Southern Ocean surrounding the Antarctic Peninsula (2008 and 2009). During these campaigns, air (gas and particulate), water (dissolved and particulate) and biota (phytoplankton) were sampled simultaneously allowing to report a complete picture of POPs cycling in polar areas. In the case of the Southern Ocean, the largest data set available for PCBs, HCH and HCB has been generated. The atmospheric and seawater concentrations were low, among the lowest reported for the Polar Oceans, and in the case of the Southern Ocean there is a clear historical trend of decreasing concentrations, consistent with reduced emissions in source regions. Long range atmospheric transport was identified as the main POPs input to polar ecosystems agreeing with previous works. However, it has been found that secondary local sources from soil and snow influences strongly the atmospheric concentrations overland in the Antarctic region, and over the adjacent Southern ocean in the case of HCHs. Atmospheric residence times calculated from the measurements were in agreement with the prediction from environmental fate models. The atmospheric residence times were longer for the less hydrophobic PCBs and shorter for the more hydrophobic, consistent with the role of the biological pump sequestering atmospheric PCBs. Once POPs reach the Polar regions the main route of entry of these compounds to surface waters is by atmospheric deposition, mainly by diffusive exchange between the gas and dissolved phase with minor contributions from dry deposition of aerosol bound POPs. Estimated bioconcentration factors revealed that concentration of POPs in phytoplankton were correlated with the chemical hydrophobicity, but some discrepancies with model predictions were observed. The biological and degradative pumps are identified as the two main processes that control the fate and occurrence of POPs in the surface water column, and also are able to modulate the atmospheric transport of POPs to remote areas. POPs such HCHs are prone to be efficiently degraded by bacterial communities in surface waters, depleting the seawater concentrations and increasing the diffusive air-water exchange to the Arctic and Southern Ocean. Conversely, the biological pump decreases the dissolved phase concentrations of the more hydrophobic PCB congeners increasing the air to water fugacity gradients and enhancing the diffusive air-water exchange fluxes. This is the first time that the influence of the biological pump on POP cycling is demonstrated for Oceanic waters. Finally, HCB was close to air-water equilibrium showing that neither the biological and degradative pumps are efficient sequestration processes for the highly persistent and mid-hydrophobic compounds. Overall, the results show clearly that biogeochemical processes occurring in the water column affect the atmospheric deposition and long range transport of POPs to remote regions.The magnitude of these processes may show a clear seasonality and are suitable to be perturbed under the current scenario of climate change.En la actualidad se usan en aplicaciones domésticas más de 200.000 compuestos orgánicos sintéticos. Muchos de estos compuestos químicos que se liberan al medio ambiente son nocivos para el medio ambiente y los humanos. Entre estos compuestos se encuentran los contaminantes orgánicos persistentes (COPs) que comprenden una serie de familias de compuestos que comparten una serie de características físico-químicas que les permiten estar distribuidos globalmente (semivolatilidad, elevada persistencia y capacidad de bioacumulacion por sus características hidrofóbicas). En la presente tesis doctoral se ha estudiado en profundidad el acoplamiento entre el transporte atmosférico y los ciclos biogeoquímicos Hexaclorociclohexanos (HCHs), Hexaclorobenceno (HCB) y Bifenilos Policlorados (PCBs) en los Océanos Polar Ártico y Polar Antártico. Durante esta tesis se han realizado tres campañas oceanográficas, una al Atlántico Norte y al Océano Polar Ártico (2007), y dos en el Océano Polar Antártico y en aguas circundantes a la Peninsula Antártica (2008 y 2009). Durante estas tres campañas oceanográficas se han tomado muestras de aire (gas y particulado), agua (disuelto y particulado) y biota (fitoplankton) de forma simultánea lo que permitió tener una amplio conocimiento de el ciclo de los COPs en zonas polares. En el caso de el Océano Polar Antártico y en aguas circundantes a la Peninsula Antártica se ha generado la mayor cantidad de datos en un mismo trabajo, incluso se han generado datos que hasta ahora no se habían publicado como las concentraciones de fitoplankton. La concentraciones medidas en el la atmósgera y aguas superficiales fueron bajas, siendo en algunos casos las concentraciones más bajas jamás encontradas en el océano polares, en el caso de el Océano Polar Antártico se ha encontrado una significativa tendencia histórica de concentraciones decrecientos lo cual es consistente con la reducción de emisiones de COPs en origen. El transporte atmosférico a larga distancia ha sido identificado como la vía de entrada principal de entrada de los COPs a sistemas polares. Sin embargo, se ha encontrado que hay fuentes secundarias provenientes de el suelo y la nieve con una clara influencia sobre las concentraciones atmosféricas en zonas de el continente Antártico y aguas costeras adyacentes en el caso de los HCHs. Los tiempos de residencia atmosférica calculados están en los mismos rangos con los modelos predictivos. Los tiempos de residencia atmosférica fieron más largos para los compuestos menos hidrofóbicos y más cortos para los más hidrófobicos lo cual es consistente con la bomba biológica. Una vez estos compuestos alcanzan las regions polares la principal ruta de entrada de estos compuestos al agua superficial es por deposición atmosférica, principalmente por intercambio difusivo entre la fase gas y la fase disuelta, se ha comprobado que la contribución de la deposición seca es significativamente menor. Los factores de bioconcentración revelaron que la concentración de COPs en el fitoplankton se correlacionaba con la hidrofobicidad química, pero se encontraron discrepancias con los modelos predictivos. Las bombas biológica y degradative han sido identificadas como los dos procesos principals que controlan el destino y ocurrencia de COPs en la columna de agua superficial e incluso son capaces de modular el transporte atmosférico de COPs a areas remotes. COPs como los HCHs son eficientemente degradados por las comunidades bacterianas de aguas superficiales disminuyendo su concentraciéon aumentando los flujos difusivos de deposición entre la fase gas y la superficie disuelta en el Océano Polar Antártico y en aguas circundantes a la Peninsula Antártica. Por otro lado, la bomba biológica disminuye las concentraciones de el disuelto de los COPs más hidrofóbicos aumentando el gradiente de fugacidades y favoreciendo la deposición por intercambio difusivo aire-agua. La presente tesis es la primera que ha demostrado la influencia de la bomba biológica influye de forma significativa el ciclo de los COPs.El HCB se ha encontrado en equilibrio en ambas zonas de estudio y no se ha demostrado que hubiera influencia de la bomba biológica o de procesos degradativos en aguas superficiales. Como conclusion final se ha demostrado a través de los resultados que los procesos biogeoquímicos en la columna de agua afectan a la deposición atmosférica y el transporte a larga distancia de COPs a regiones remotas. La magnitud de estos procesos muestra una clara estacionalidad que puede ser perturbada en un actual escenario de cambio climático

Orientación de la enseñanza de la actividad oral disciplinar: una necesidad en la Educación Superior

El presente trabajo tiene como propósito reflexionar en torno a la necesidad de una orientación de la enseñanza de la actividad oral sobre contenidos disciplinares que contribuyan no solo hablar en ciencias, sino también a una inserción a la lectura y escritura como prácticas representativas. Los aspectos que se instalan en la concepción de la enseñanza fueron el producto de la sistematización teórica de estudios sobre la temática, los cuales fueron complementados a través de la aplicación de entrevista y observación como técnicas fundamentales. Se ofrece como resultado una propuesta de acciones para el trabajo didáctico con implicación directa en la complementariedad y secuenciación de actividades para la enseñanza de la actividad oral disciplinar, la cual es resultado parcial de proyecto “Metodología para la profesionalización de la formación en Lengua Inglesa en la Universidad de Camagüey (código: F82CM908076)”. PALABRAS CLAVE: orientación de la enseñanza; actividad oral disciplinar; complementariedad; secuenciación de actividades. Teaching orientation of oral activity in disciplines: a need in Higher Education ABSTRACT The present paper aims at reflecting on the need of an orientation of teaching oral activity on disciplinar contents that contributes not only to speak in science, but also to an insertion to reading and writing as representative practices of disciplines. The aspects installed in this orientation of teaching were the results of the theoretical systematization of different studies on the field, validated through an interview and a class observation as main techniques. A proposal of actions for the didactic work, with a direct implication in the designing and sequencing of activities, is offered as a partial result of the project “Methodology for professionalizing the students’ formation in the English Language in University of Camagüey (code: F82CM908076)”. KEYWORDS: teaching orientation; oral disciplinary activity; complementarity; activity sequencing

Occurrence and diffusive air-seawater exchanges of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in Fildes Bay, King George Island, Antarctica

We report the levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in seawater and air, and the air-sea dynamics through diffusive exchange analysis in Fildes Bay, King George Island, Antarctica, between November 2019 and January 30, 2020. Hexachlorobenzene (HCB) was the most abundant compound in both air and seawater with concentrations around 39 ± 2.1 pg m−3 and 3.2 ± 2.4 pg L−1 respectively. The most abundant PCB congener was PCB 11, with a mean of 3.16 ± 3.7 pg m−3 in air and 2.0 ± 1.1 pg L−1 in seawater. The fugacity gradient estimated for the OCP compounds indicate a predominance of net atmospheric deposition for HCB, α-HCH, γ-HCH, 4,4′-DDT, 4,4′-DDE and close to equilibrium for the PeCB compound. The observed deposition of some OCs may be driven by high biodegradation rates and/or settling fluxes decreasing the concentration of these compounds in surface waters, which is supported by the capacity of microbial consortium to degrade some of these compounds. The estimated fugacity gradients for PCBs showed differences between congeners, with net volatilization predominating for PCB-9, a trend close to equilibrium for PCB congeners 11, 28, 52, 101, 118, 138, and 153, and deposition for PCB 180. Snow amplification may play an important role for less hydrophobic PCBs, with volatilization predominating after snow/glacier melting. As hydrophobicity increases, the biological pump decreases the concentration of PCBs in seawater, reversing the fugacity gradient to atmospheric deposition. This study highlights the potential impacts of climate change, through glacier retreat, on the biogeochemistry of POPs, remobilizing those compounds previously trapped within the cryosphere which in turn will transform the Antarctic cryosphere into a secondary source of the more volatile POPs in coastal areas, influenced by snow and ice melting

Levels of persistent organic pollutants (POPs) in the Antarctic atmosphere over time (1980 to 2021) and estimation of their atmospheric half-lives

Persistent organic pollutants (POPs) are synthetic compounds that were intentionally produced in large quantities and have been distributed in the global environment, originating a threat due to their persistence, bioaccumulative potential, and toxicity. POPs reach the Antarctic continent through long-range atmospheric transport (LRAT). In these areas, low temperatures play a significant role in the environmental fate of POPs, retaining them for a long time due to cold trapping by diffusion and wet deposition, acting as a net sink for many POPs. However, in the current context of climate change, the remobilization of POPs that were trapped in water, ice, and soil for decades is happening. Therefore, continuous monitoring of POPs in polar air is necessary to assess whether there is a recent re-release of historical pollutants back to the environment. We reviewed the scientific literature on atmospheric levels of several POP families (polychlorinated biphenyls - PCBs, hexachlorobenzene - HCB, hexachlorocyclohexanes - HCHs, and dichlorodiphenyltrichloroethane - DDT) from 1980 to 2021. We estimated the atmospheric half-life using characteristic decreasing times (TD). We observed that HCB levels in the Antarctic atmosphere were higher than the other target organochlorine pesticides (OCPs), but HCB also displayed higher fluctuations and did not show a significant decrease over time. Conversely, the atmospheric levels of HCHs, some DDTs, and PCBs have decreased significantly. The estimated atmospheric half-lives for POPs decreased in the following order: 4,4' DDE (13.5 years) > 4,4' DDD (12.8 years) > 4,4' DDT (7.4 years) > 2,4' DDE (6.4 years) > 2,4' DDT (6.3 years) > α-HCH (6 years) > HCB (6 years) > 3-HCH (4.2 years). For PCB congeners, they decreased in the following order: PCB 153 (7.6 years) > PCB 138 (6.5 years) > PCB 101 (4.7 years) > PCB 180 (4.6 years) > PCB 28 (4 years) > PCB 52 (3.7 years) > PCB 118 (3.6 years). For HCH isomers and PCBs, the Stockholm Convention (SC) ban on POPs did have an impact on decreasing their levels during the last decades. Nevertheless, their ubiquity in the Antarctic atmosphere shows the problematic issues related to highly persistent synthetic chemicals.This study was funded by ANID/FONDE CYT/Iniciación 11150548, ANID/FONDECYT/Regular 1161504, ANID/FONDECYT/Regular 1210946, ANID/PCI REDI170292, ANID-PIA-INACH-ACT192057, INACH REGULAR RT_12_17 https://doi.org/10.5194/acp-23-8103-2023 Atmos. Chem. Phys., 23, 8103–8118, 2023 8114 T. Luarte et al.: POP trends in the Antarctic atmosphere (Cristóbal Galbán-Malagón). Support through the PhD Grant Program and INACH DG_02_21.Peer reviewe

Effects of intubation timing in patients with COVID-19 throughout the four waves of the pandemic : a matched analysis

The primary aim of our study was to investigate the association between intubation timing and hospital mortality in critically ill patients with COVID-19-associated respiratory failure. We also analysed both the impact of such timing throughout the first four pandemic waves and the influence of prior non-invasive respiratory support on outcomes. This is a secondary analysis of a multicentre, observational and prospective cohort study that included all consecutive patients undergoing invasive mechanical ventilation due to COVID-19 from across 58 Spanish intensive care units (ICU) participating in the CIBERESUCICOVID project. The study period was between 29 February 2020 and 31 August 2021. Early intubation was defined as that occurring within the first 24 h of intensive care unit (ICU) admission. Propensity score (PS) matching was used to achieve balance across baseline variables between the early intubation cohort and those patients who were intubated after the first 24 h of ICU admission. Differences in outcomes between early and delayed intubation were also assessed. We performed sensitivity analyses to consider a different timepoint (48 h from ICU admission) for early and delayed intubation. Of the 2725 patients who received invasive mechanical ventilation, a total of 614 matched patients were included in the analysis (307 for each group). In the unmatched population, there were no differences in mortality between the early and delayed groups. After PS matching, patients with delayed intubation presented higher hospital mortality (27.3% versus 37.1%, p =0.01), ICU mortality (25.7% versus 36.1%, p=0.007) and 90-day mortality (30.9% versus 40.2%, p=0.02) when compared to the early intubation group. Very similar findings were observed when we used a 48-hour timepoint for early or delayed intubation. The use of early intubation decreased after the first wave of the pandemic (72%, 49%, 46% and 45% in the first, second, third and fourth wave, respectively; first versus second, third and fourth waves p<0.001). In both the main and sensitivity analyses, hospital mortality was lower in patients receiving high-flow nasal cannula (n=294) who were intubated earlier. The subgroup of patients undergoing NIV (n=214) before intubation showed higher mortality when delayed intubation was set as that occurring after 48 h from ICU admission, but not when after 24 h. In patients with COVID-19 requiring invasive mechanical ventilation, delayed intubation was associated with a higher risk of hospital mortality. The use of early intubation significantly decreased throughout the course of the pandemic. Benefits of such an approach occurred more notably in patients who had received high-flow nasal cannul

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation

Higher COVID-19 pneumonia risk associated with anti-IFN-α than with anti-IFN-ω auto-Abs in children

We found that 19 (10.4%) of 183 unvaccinated children hospitalized for COVID-19 pneumonia had autoantibodies (auto-Abs) neutralizing type I IFNs (IFN-alpha 2 in 10 patients: IFN-alpha 2 only in three, IFN-alpha 2 plus IFN-omega in five, and IFN-alpha 2, IFN-omega plus IFN-beta in two; IFN-omega only in nine patients). Seven children (3.8%) had Abs neutralizing at least 10 ng/ml of one IFN, whereas the other 12 (6.6%) had Abs neutralizing only 100 pg/ml. The auto-Abs neutralized both unglycosylated and glycosylated IFNs. We also detected auto-Abs neutralizing 100 pg/ml IFN-alpha 2 in 4 of 2,267 uninfected children (0.2%) and auto-Abs neutralizing IFN-omega in 45 children (2%). The odds ratios (ORs) for life-threatening COVID-19 pneumonia were, therefore, higher for auto-Abs neutralizing IFN-alpha 2 only (OR [95% CI] = 67.6 [5.7-9,196.6]) than for auto-Abs neutralizing IFN-. only (OR [95% CI] = 2.6 [1.2-5.3]). ORs were also higher for auto-Abs neutralizing high concentrations (OR [95% CI] = 12.9 [4.6-35.9]) than for those neutralizing low concentrations (OR [95% CI] = 5.5 [3.1-9.6]) of IFN-omega and/or IFN-alpha 2

Pharmaceutical pollution of the world's rivers

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world's rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals

Persistent Organic Pollutants in Antarctica

Persistent organic pollutants (POPs) are carbon-based chemicals of anthropogenic origin that elicit toxic effects in organisms. For this reason, the United Nations Environment Programme implemented the Stockholm Convention on POPs in 2004 to protect human health and the environment. Due to their physical-chemical properties, POPs are readily transported over long distances to remote areas, including polar regions, where they are trapped because of the extreme cold climate. Once in the Antarctic region, they bioaccumulate in organism and food webs and can show their toxic effects. Antarctica and Southern Ocean ecosystems are fragile and have low resilience capacity, thus contamination can have unpredictable consequences. Moreover, global climate change stands to influence the abiotic drivers of chemical distribution and mobility in Antarctic ecosystems. Thus, a knowledge of concentrations and distributions of contaminants is necessary to understand the risk to Antarctica and for evaluating the overall environmental health and other possible consequences at a global scale