Mutual interaction between arsenic and biofilm in a mining impacted river

Gold mining activities in fluvial systems may cause arsenic (As) pollution, as is the case at the Anllóns River (Galicia, NW Spain), where high concentrations of arsenate (AsV) in surface sediments (up to 270 mg kg−1) were found. A 51 day-long biofilm-translocation experiment was performed in this river, moving some biofilm-colonized substrata from upstream (less As-polluted) to downstream the mine area (more As-polluted site), to explore the effect of As on benthic biofilms, as well as their role on As retention and speciation in the water-sediment interface. Eutrophic conditions (range: 0.07–0.38 mg L−1 total phosphorus, TP) were detected in water in both sites, while sediments were not considered P-polluted (below 600 mg kg−1). Dimethylarsenate (DMAV) was found intracellularly and in the river water, suggesting a detoxification process by biofilms. Since most As in sediments and water was AsV, the high amount of arsenite (AsIII) detected extracellularly may also confirm AsV reduction by biofilms. Furthermore, translocated biofilms accumulated more As and showed higher potential toxicity (higher As/P ratio). In concordance, their growth was reduced to half that observed in those non-translocated, became less nutritive (less nitrogen content), and with higher bacterial and dead diatom densities. Besides the high As exposure, other environmental conditions such as the higher riparian cover at the more As-polluted site could contribute to those effects. Our study provides new arguments to understand the contribution of microorganisms to the As biogeochemistry in freshwater environmentsThis work was supported by the Spanish Ministry of Economy and Competitiveness (Project Ref. CGL2010-22059, CGL2013-46003-P and CGL2013-43822-R), the University of Girona (Project Ref. SING12/09 and MPCUdG2016/120) and the Government of Catalonia (Project Ref. 2014 SGR 484). Laura Barral Fraga benefited from a doctoral fellowship from the University of Girona (BR 2013/06) and a mobility grant from the Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA, at Bordeaux, France)S

Autoextermínio e formação profissional

During academic training, suicide acquires significant expression and medical students are more susceptible to suicidal ideation and suicide itself. In this sense, the objective was to reflect on suicide among undergraduate medical students in Brazil. This is a descriptive study, with a critical-reflexive nature and a qualitative approach, which aims to unravel the theory of generation Z through the students of the Graduate School of Medicine in Brazil who commit or carry out attempts at self-extermination. As a result, the disagreement between what is lived in a virtual environment and the real one generates conflicts between members of generation Z. The listening process, when done properly, helps to improve people's mental health and should be considered and encouraged in university environments. However, we are faced with the unpreparedness of society to deal with students who are more susceptible to suicidal ideation. It is important to train health professionals, as well as the development of educational lectures and the construction of psycho-emotional support centers in higher education institutions, in order to prevent the act of suicide to medical students in Brazil.Durante a formação acadêmica o suicídio adquire significativa expressão e os estudantes de medicina estão mais susceptíveis a ideação suicida e ao próprio suicídio. Nesse sentido, objetivou-se refletir sobre o suicídio entre estudantes de Graduação de Medicina do Brasil. Trata-se de um estudo descritivo, de caráter crítico-reflexivo e abordagem qualitativa, que visa desvendar a teoria da geração Z através dos alunos da Graduação de Medicina do Brasil que cometem ou realizam tentativas de autoextermínio. Obteve como resultado que a discordância entre o que se vive em ambiente virtual e o real gera conflitos entre membros da geração Z. O processo de escuta, quando feito adequadamente, auxilia na melhoria da saúde mental das pessoas devendo ser considerado e estimulado nos ambientes universitários. Contudo, deparamos com o despreparo da sociedade para lidar com estudantes mais susceptíveis a ideação suicida. Torna-se importante a capacitação de profissionais da área da saúde, assim como o desenvolvimento de palestras educativas e a construção de centros de apoio psicoemocional nas instituições de ensino superior, afim de prevenir o ato de suicídio aos acadêmicos de medicina no Brasil

Autoextermínio e formação profissional

During academic training, suicide acquires significant expression and medical students are more susceptible to suicidal ideation and suicide itself. In this sense, the objective was to reflect on suicide among undergraduate medical students in Brazil. This is a descriptive study, with a critical-reflexive nature and a qualitative approach, which aims to unravel the theory of generation Z through the students of the Graduate School of Medicine in Brazil who commit or carry out attempts at self-extermination. As a result, the disagreement between what is lived in a virtual environment and the real one generates conflicts between members of generation Z. The listening process, when done properly, helps to improve people's mental health and should be considered and encouraged in university environments. However, we are faced with the unpreparedness of society to deal with students who are more susceptible to suicidal ideation. It is important to train health professionals, as well as the development of educational lectures and the construction of psycho-emotional support centers in higher education institutions, in order to prevent the act of suicide to medical students in Brazil.Durante a formação acadêmica o suicídio adquire significativa expressão e os estudantes de medicina estão mais susceptíveis a ideação suicida e ao próprio suicídio. Nesse sentido, objetivou-se refletir sobre o suicídio entre estudantes de Graduação de Medicina do Brasil. Trata-se de um estudo descritivo, de caráter crítico-reflexivo e abordagem qualitativa, que visa desvendar a teoria da geração Z através dos alunos da Graduação de Medicina do Brasil que cometem ou realizam tentativas de autoextermínio. Obteve como resultado que a discordância entre o que se vive em ambiente virtual e o real gera conflitos entre membros da geração Z. O processo de escuta, quando feito adequadamente, auxilia na melhoria da saúde mental das pessoas devendo ser considerado e estimulado nos ambientes universitários. Contudo, deparamos com o despreparo da sociedade para lidar com estudantes mais susceptíveis a ideação suicida. Torna-se importante a capacitação de profissionais da área da saúde, assim como o desenvolvimento de palestras educativas e a construção de centros de apoio psicoemocional nas instituições de ensino superior, afim de prevenir o ato de suicídio aos acadêmicos de medicina no Brasil

Arsenic and fluvial biofilms: biogeochemistry, toxicity and biotic interactions

Based on the current knowledge about biofilm ecotoxicology and arsenic biogeochemistry in freshwater ecosystems, this thesis studied, under realistic environmental concentrations, i) the role of benthic biofilms in the bioavailability and detoxification of arsenic, ii) the toxic effects of Arsenic on the structure and function of river benthic biofilms, paying special attention to the responses of diatoms, and iii) the interaction between these primary producers and higher organisms such as fish, exposed to arsenic. Arsenic inhibited algal growth, with diatoms being adapted by a significant reduction in cell biovolume (chapter 1). The biofilm aggravated the effects of arsenic on fish (chapter 2) but was also able to detoxify through methylation of inorganic arsenic species (chapter 3). The results of this thesis provide valuable information to understand the contribution of biofilms to biogeochemistry and arsenic toxicity in freshwater systems.Basándonos en los conocimientos actuales sobre la ecotoxicología del biofilm y la biogeoquímica del arsénico en ecosistemas dulceacuícolas, esta tesis estudió, bajo concentraciones ambientales realistas, i) el papel de los biofilms bentónicos en la biodisponibilidad y destoxificación del arsénico, ii) los efectos tóxicos del arsénico sobre la estructura y función de los biofilms bentónicos fluviales, prestando especial atención a las respuestas de las diatomeas, y iii) la interacción entre estos productores primarios y organismos superiores como los peces, expuestos a arsénico. El arsénico inhibió el crecimiento algal, pudiendo las diatomeas adaptarse mediante una significativa reducción de su biovolumen celular (capítulo 1). El biofilm agravó los efectos del arsénico en peces (capítulo 2) pero también fue capaz de destoxificar metilando especies inorgánicas de arsénico (capítulo 3). Los resultados de esta tesis proporcionan información valiosa para comprender la contribución de los biofilms a la biogeoquímica y toxicidad del arsénico en sistemas dulceacuícolas.CAT: S'han extret de la tesi doctoral el contingut del cap. 1 General introduction i Cap. 4 General discussion; part del capítol 3 que inclouen articles en preparació. També s'han extret els Annexos 1 i 2 que incloïen els pdf editor d'articles ja publicats.----- ENG: The content of Chapter 1. General introduction and Chapter 4 General discussion; part of Chapter 3 that have articles in preparation have been extracted from the doctoral thesis pdf. Appendices 1 2 that included the pdf editor of articles already published have been extracted from the doctoral thesis too

Mutual interaction between Arsenic and biofilm in a mining impacted river

Gold mining activities in fluvial systems may cause arsenic (As) pollution, as is the case at the Anllóns River (Galicia, NW Spain), where high concentrations of arsenate (AsV) in surface sediments (up to 270 mg kg−1) were found. A 51 day-long biofilm-translocation experiment was performed in this river, moving some biofilm-colonized substrata from upstream (less As-polluted) to downstream the mine area (more As-polluted site), to explore the effect of As on benthic biofilms, as well as their role on As retention and speciation in the water-sediment interface. Eutrophic conditions (range: 0.07-0.38 mg L−1 total phosphorus, TP) were detected in water in both sites, while sediments were not considered P-polluted (below 600 mg kg−1). Dimethylarsenate (DMAV) was found intracellularly and in the river water, suggesting a detoxification process by biofilms. Since most As in sediments and water was AsV, the high amount of arsenite (AsIII) detected extracellularly may also confirm AsV reduction by biofilms. Furthermore, translocated biofilms accumulated more As and showed higher potential toxicity (higher As/P ratio). In concordance, their growth was reduced to half that observed in those non-translocated, became less nutritive (less nitrogen content), and with higher bacterial and dead diatom densities. Besides the high As exposure, other environmental conditions such as the higher riparian cover at the more As-polluted site could contribute to those effects. Our study provides new arguments to understand the contribution of microorganisms to the As biogeochemistry in freshwater environment

Biotic and Abiotic Factors Influencing Arsenic Biogeochemistry and Toxicity in Fluvial Ecosystems: A Review

Este artículo contiene 28 páginas, 6 figuras, 1 tabla.This review is focused on the biogeochemistry of arsenic in freshwaters and, especially, on the key role that benthic microalgae and prokaryotic communities from biofilms play together in through speciation, distribution, and cycling. These microorganisms incorporate the dominant iAs (inorganic arsenic) form and may transform it to other arsenic forms through metabolic or detoxifying processes. These transformations have a big impact on the environmental behavior of arsenic because different chemical forms exhibit differences in mobility and toxicity. Moreover, exposure to toxicants may alter the physiology and structure of biofilms, leading to changes in ecosystem function and trophic relations. In this review we also explain how microorganisms (i.e., biofilms) can influence the effects of arsenic exposure on other key constituents of aquatic ecosystems such as fish. At the end, we present two real cases of fluvial systems with different origins of arsenic exposure (natural vs. anthropogenic) that have improved our comprehension of arsenic biogeochemistry and toxicity in freshwaters, the Pampean streams (Argentina) and the Anllóns River (Galicia, Spain). We finish with a briefly discussion of what we consider as future research needs on this topic. This work especially contributes to the general understanding of biofilms influencing arsenic biogeochemistry and highlights the strong impact of nutrient availability on arsenic toxicity for freshwater (micro) organisms.This research was funded by the Spanish Ministry of Economy and Competitiveness (MINECO-FEDER) (ProjectRef. CGL2010-22059,CGL2013-46003-P,andCGL2013-43822-R),the program“Ayudas de Consolidación e Estructuración de Unidades de Investigación Competitivas”(ProjectRef. GRC2014/028) from the Xunta de Galicia, also the Generalitat de Catalunya (ref. 2017 SGR 548), and the University of Girona (Project Ref. SING12/09 and MPCUdG2016/120). Laura Barral Fraga benefited from a doctoral fellowship from the University of Girona (BR 2013/06) and a mobility grant from the Institut national de recherche en sciences et technologies pour l’environnement et l’agriculture (IRSTEA) at Bordeaux, France.Peer reviewe

Hypersaline mining effluents affect the structure and function of stream biofilm

The salinisation of freshwater ecosystems is a global environmental problem that threatens biodiversity, ecosystem functioning and human welfare. The aim of this study was to investigate the potential impact of a realistic salinity gradient on the structure and functioning of freshwater biofilms. The salinity gradient was based on the real ion concentration of a mining effluent from an abandoned mine in Germany. We exposed biofilm from a pristine stream to 5 increasing salinities (3 to 100 g L-1) under controlled conditions in artificial streams for 21 days. We evaluated its functional (photosynthetic efficiency, nutrient uptake, and microbial respiration) and structural responses (community composition, algal biomass and diatom, cyanobacteria and green algae metrics) over time. Then we compared their responses with an unexposed biofilm used as control. The functionality and structure of the biofilm exposed to the different salinities significantly decreased after short-term and long-term exposure, respectively. The community composition shifted to a new stable state where the most tolerant species increased their abundances. At the same time, we observed an increase in the community tolerance (measured as Pollution-Induced Community Tolerance) along the salinity gradient. This study provides relevant information on the salt threshold concentrations that can substantially damage algal cells (i.e., between 15 and 30 g L-1). The results provide new insights regarding the response and adaptation of stream biofilm to salinity and its potential implications at the ecosystem level.We thank T.S and A.S from the Dresden Groundwater Research Center for the information about Menteroda abandoned mine provided. Lorenzo Proia that has received funding from the Postdoctoral Fellowships Programme Beatriu de Pinos, funded by the Secretary of Universities and Research (Government of Catalonia) and by the Horizon 2020 Programme of Research and Innovation of the European Union under the Marie Skłodowska-Curie Grant Agreement No. 801370 and by a Ramón y Cajal contract funded by the Spanish Ministry of Science and Innovation (RYC2020-029829-I). Miguel Cañedo-Argüelles was supported by the Serra-Hunter programme funded by the Generalitat of Catalunya and by a Ramón y Cajal contract funded by the Spanish Ministry of Science and Innovation (RYC2020-029829-I).Peer reviewe

Impacts of diffuse urban stressors on stream benthic communities and ecosystem functioning: A review

Catchment urbanisation results in urban streams being exposed to a multitude of stressors. Notably, stressors originating from diffuse sources have received less attention than stressors originating from point sources. Here, advances related to diffuse urban stressors and their consequences for stream benthic communities are summarised by reviewing 92 articles. Based on the search criteria, the number of articles dealing with diffuse urban stressors in streams has been increasing, and most of them focused on North America, Europe, and China. Land use was the most common measure used to characterize diffuse stressor sources in urban streams (70.7 % of the articles characterised land use), and chemical stressors (inorganic nutrients, xenobiotics, metals, and water properties, including pH and conductivity) were more frequently reported than physical or biological stressors. A total of 53.3 % of the articles addressed the impact of urban stressors on macroinvertebrates, while 35.9 % focused on bacteria, 9.8 % on fungi, and 8.7 % on algae. Regarding ecosystem functions, almost half of the articles (43.5 %) addressed changes in community dynamics, 40.3 % addressed organic matter decomposition, and 33.9 % addressed nutrient cycling. When comparing urban and non-urban streams, the reviewed studies suggest that urbanisation negatively impacts the diversity of benthic organisms, leading to shifts in community composition. These changes imply functional degradation of streams. The results of the present review summarise the knowledge gained to date and identify its main gaps to help improve our understanding of urban streams.This study has received funding from the Iberian Association of Limnology (AIL) through the project URBIFUN (Urbanization effects on the relationship between microbial biodiversity and ecosystem functioning), awarded to Míriam Colls and Ferran Romero. Authors thank as well the Basque Government (Consolidated Research Group IT951-16) and the MERLIN project 101036337 – H2020-LC-GD-2020/H2020-LC-GD-2020-3.info:eu-repo/semantics/publishedVersio

Impacts of diffuse urban stressors on stream benthic communities and ecosystem functioning : a review

Abstract: Catchment urbanisation results in urban streams being exposed to a multitude of stressors. Notably, stressors originating from diffuse sources have received less attention than stressors originating from point sources. Here, advances related to diffuse urban stressors and their consequences for stream benthic communities are summarised by reviewing 92 articles. Based on the search criteria, the number of articles dealing with diffuse urban stressors in streams has been increasing, and most of them focused on North America, Europe, and China. Land use was the most common measure used to characterize diffuse stressor sources in urban streams (70.7 % of the articles characterised land use), and chemical stressors (inorganic nutrients, xenobiotics, metals, and water properties, including pH and conductivity) were more frequently reported than physical or biological stressors. A total of 53.3 % of the articles addressed the impact of urban stressors on macroinvertebrates, while 35.9 % focused on bacteria, 9.8 % on fungi, and 8.7 % on algae. Regarding ecosystem functions, almost half of the articles (43.5 %) addressed changes in community dynamics, 40.3 % addressed organic matter decomposition, and 33.9 % addressed nutrient cycling. When comparing urban and non-urban streams, the reviewed studies suggest that urbanisation negatively impacts the diversity of benthic organisms, leading to shifts in community composition. These changes imply functional degradation of streams. The results of the present review summarise the knowledge gained to date and identify its main gaps to help improve our understanding of urban streams