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

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

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

Dichlorodiphenyltrichloroethane (DDT) and Dichlorodiphenyldichloroethylene (DDE) levels in air and surface sea waters along the Antarctic Peninsula

Persistent organic pollutants (POPs) are widespread worldwide, even reaching polar regions. Among POPs, dichlorodiphenyltrichloroethane (DDT) and their metabolites have been reported scarcely in the Antarctic environment. Here we report the levels of p,p'-DDT, o,p'-DDT, p,p'-DDE, and o,p'-DDE in air and water samples collected during austral summer 2009. The levels found ranged from 0.25 to 4.26 pg m-3 in the atmospheric samples while in the water samples ranged from 0.07 to 0.25 pg L-1. These concentrations were within the range of the reported concentrations in the last 20 years in Antarctica. However, the source ratio showed that most of p,p'-DDT comes from fresh applications and Dicofol formulations. The back-trajectories estimated for the air masses revealed that most of the p,p'-DDT came from the continental Antarctic peninsula and surrounding waters. The diffusive exchange direction showed that Antarctic surface waters are the final sink of the studied compounds during the survey period.CGM acknowledges funding from the ANID FONDECYT REGULAR 1210946, ANID-PIA-INACH-ACT192057, and INACH REGULAR RT_12_17; VG is supported through an ANID FONDECYT POSTDOC 3230076; TL is supported through the INACH DG_02_21. The authors acknowledge the R/V Hespérides crew. This work was also funded by the ATOS project of the Spanish Ministry of Science and Innovation.Peer reviewe

Latitudinal patterns in the diet of Andean condor (Vultur gryphus) in Chile: Contrasting environments influencing feeding behavior

Human-dominated environments alter the availability and quality of resources for many species, especially for scavengers that have large home ranges and plastic foraging behaviors that enable them to exploit novel resources. Along the western slope of the Andes, the modification of natural landscapes have resulted in significant declines in native prey, the introduction of non-native species, and an increase in the availability of anthropogenic resources. These factors have likely influenced the resources available to Andean condors (Vultur gryphus), however, data are lacking as to how condor's diet vary along their large latitudinal range. We evaluated differences in Andean condor diet along a similar to 2500 km latitudinal gradient in Chile from the heavily modified Central zone (32-34 degrees S) to the more pristine Austral zone (44-56 degrees S). We assessed diet composition through the identification of prey remains in condor pellets, and carbon and nitrogen isotope analysis of condor feathers and their primary prey identified from pellet analysis. Our results identified medium- and large-bodied domesticated mammals (ungulates) and introduced exotic species (lagomorphs) as common prey across the study area. Condors from the Central zone had the largest isotopic niche width, probably related to consumption of anthropogenic resources with distinctly high carbon isotope values indicative of C-4-based foods likely acquired from landfills or corn-fed livestock. Isotopic niches for condors from the Southern and Austral zones almost completely overlapped. Andean condor diet is strongly influenced by local conditions determining differential access to prey sources. The high dependence of Andean condors on livestock across a large geographical area, and landfills in more (sub)urban areas, may help stabilize their populations via anthropogenic resources subsidies. Long-term dependence on such resources, however, may have health costs including contaminant exposure and greater mortality risk. These data will help identify potential threats related to resource availability and use, and better inform management and conservation decisions.Agencia Nacional de Investigacion y Desarrollo FB0002 192057 Rufford Small Grants Foundation 26414 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 11130245 1200386 1115054

Occurrence and air-water diffusive exchange legacy persistent organic pollutants in an oligotrophic north Patagonian lake

In this study, the occurrence and diffusive air-water exchange of POPs in Panguipulli Lake (39°42'S-72°13'W), an oligotrophic lake located in northern Patagonia (Chile), were determined. Air and water samples were collected between March and August 2017 (autumn-winter) and analyzed for concentrations of OCPs (α-HCH, β-HCH, γ-HCH and HCB) and PCBs (PCB-28,-52,-101,-118,-153,-158,-180) using gas chromatography coupled with an electron capture detector. The direction of air-water exchange direction was evaluated using a fugacity approach (ƒw ƒa-1), and net diffusive exchange fluxes (FAW, ng m-2 d-1) were also estimated. Total ∑4OCP levels in air ranged from 0.31 to 37 pg m-3, with a maximum for β-HCH, while Σ7PCB levels ranged from 3.05 to 43 pg m-3. The most abundant congener was PCB-153, accounting for 60% of the total PCBs in air. Surface water ∑4OCPs measured in this study ranged from 1.01 to 3.9 pg L-1, with γ-HCH predominating, while surface water Σ7PCB levels ranged from 0.32 to 24 pg L-1, with PCB-101, PCB-118, and PCB-153 presenting the highest levels. Diffusive air-water exchanges of HCB, α-HCH, γ-HCH and PCBs in the form of volatilization from the lake to air predominated; in contrast, for β-HCH net deposition dominated during the sampling period. Estimates suggested faster microbial degradation in the dissolved phase compared to atmospheric degradation for all analyzed POPs. Overall, these results could indicate that the oligotrophic lakes of northern Patagonia act as a secondary source of atmospheric POPs, mainly PCBs and some OCPs. This study is a first attempt to understand the occurrence of POPs in air and water, as well as their dynamics in oligotrophic lakes in the southern hemisphere.This study was funded by ANID/FONDECYT/Iniciación 11150548, ANID/FONDECYT/Regular 1161504, ANID/FONDECYT/Regular 1210946, ANID/PCI REDI170292, ANID PIA INACH ACT192057, INACH REGULAR RT_12_17 (C. Galbán-Malagón) and ANID/FONDECYT/Postdoctorado Nº3180159 (F. Tucca). Additionally, the authors acknowledge the support of the ANID/FONDAP/CRHIAM/15130015 and ANID/FONDECYT/1161673 projects (R. Barra). The authors are grateful for the logistical help of the Universidad Austral de Chile in the collection of water and air samples at Panguipulli Lake.Peer reviewe

Sources and diffusive air–water exchange of polycyclic aromatic hydrocarbons in an oligotrophic North–Patagonian lake

Polycyclic aromatic hydrocarbons (PAHs) are semivolatile organic compounds of environmental concern. This study aims to investigate the influence of local sources of anthropogenic PAHs and their air–water exchange fluxes in an oligotrophic North–Patagonian lake in Chile. The monitoring was carried out in Panguipulli Lake during a six-month period during the autumn and winter seasons (March to August 2017) using a high–volume air sampler and a pump system for water samples. We detected and quantified fifteen PAHs in the gas phase (mean ∑PAHs = 11.6 ng m) and dissolved water phase (mean ∑PAHs = 961.8 pg L). Methylphenanthrenes and pyrene dominated the concentrations of PAHs in the studied phases. To determine sources of PAHs we used the PAH ratios of Light Molecular Weight/Heavy Molecular Weight (∑LMW/∑HMW) and Phenanthrene/Anthracene (Phe/Ant). The PAH ratio results revealed a pyrogenic source. We estimated the air–water diffusive exchange fluxes and fugacity ratios for the studied compounds. In general, air–water diffusive exchanges of PAHs showed a net volatilization for the less hydrophobic (log K < 4) and lighter PAHs (MW ≤ 170 g mol), and a net deposition trend for the more hydrophobic (log K 4–7) and higher molecular weight PAHs (MW ≥ 178 g mol). We found a significant correlation between log water/air fugacity ratios and log K of PAHs. Therefore, it is suggested that this oligotrophic lake acts as a sink by accumulating hydrophobic and mid-high molecular weight PAHs derived mainly from pyrogenic sources. This study is the first attempt to understand the sources and behavior of PAHs in oligotrophic lakes in the Southern Chile where information is scarce regarding the occurrence of PAHs.This study was funded by ANID FONDECYT 11150548, 1161504, ANID PCI REDI170292, ANID PIA Anillo INACH ACT192057, INACH REGULAR RT_12_17 (C. Galbán-Malagón) and ANID FONDECYT N° 3180159 (F. Tucca). Authors also thank the support of ANID FONDAP CRHIAM 15130015 (R. Barra and F. Tucca), ANID FONDECYT 1161673 (K. Pozo), “Universidad Andrés Bello” is thanked for funding a PhD scholarship awarded to Miss Thais Luarte. The “Universidad Austral de Chile” was highly acknowledged by their continuous logistic support on the lake. Kevin Ryan PhD(c) is thanked for language editing of the final version of the present manuscript