Uma proposta de critérios ambientais, sociais e de governança (ESG) para o setor de saneamento / A proposal of ESG (environmental, social and governance) criteria for water supply and sanitation sector

O combate às mudanças climáticas requer ações coletivas e através de uma nova governança que integre a sustentabilidade e gere valor compartilhado no longo prazo. Considerando o cenário do saneamento e o potencial de atração de investimentos existe uma relação simbiótica entre saneamento e desenvolvimento econômico. O ESG pode ser utilizado como ferramenta de gestão de riscos e como diretriz de comunicação às partes interessadas por organizações. Por meio de pesquisa exploratória de caráter aplicado, esse estudo desenvolveu critérios para avaliação do engajamento das companhias estaduais de saneamento com relação ao ESG. Os resultados indicam diferentes status de engajamento, diferentes metodologias e grandes oportunidades de melhoria no setor. A maioria das companhias estaduais não reporta seus dados não financeiros de forma sistemática e transparente. Os critérios apresentados podem ser utilizados por agências ambientais, fiscalizadoras e para tomada de decisão por diferentes instituições.

Climate change combating demands collective actions through a new governance which integrates sustainability and generates shared value in the long term. Considering sanitation scenario and the potential of investments attraction, there is an symbiotic relation between sanitation and economic development. The ESG criteria can be used as a tool for risk management and as a communication guidance for stakeholders. This study was developed through exploratory applied research and has proposed criteria to assess engagement of state sanitation companies regarding ESG (environmental, social and governance) standards. Results indicated different engagement status, different methodologies being applied and huge improvement opportunities in the sanitation sector. Most of the companies does not report non finance data in a systematic and transparent way. Criteria presented in this work may be used by environmental and enforcement agencies and for decision making at different institutions.

A new freshwater snail genus and species (Gastropoda: Caenogastropoda, Cochliopidae) with extremely spinous shells from sub-recent spring deposits in northeastern Mexico.

A new monotypic genus of freshwater snail from late Holocene spring deposits in Viesca, Coahuila (Mexico), is described based on shell morphology. Spinopyrgus luismaedai n. gen. et n. sp. has two to three carinate shells with long and wide shovel-shaped spines, strong axial ridges and a pointed protoconch. All sculptural ornamentations on the teleoconch are part of the calcareous shell material and not projections of the periostracum. This combination of shell features and their almost marine-like appearance is unknown among North American recent and fossil freshwater snails. Because of its shell characteristics, we placed the new genus tentatively in the Cochliopidae. The springs of Viesca dried up in the second half of the 20th century so that any living occurrence of this species in neighboring areas is unlikely, rendering the new genus and species possibly extinct.

Simulation of alpha particle emitted by 222Rn from natural spring water in Puebla, México.

A computational simulation of alpha-particle expansion, emitted by 222Rn naturally diluted in the water of a spring located in the state of Puebla Mexico, is presented. This simulation provided information on the volume of expansion of the alpha particles in the vicinity of the spring and thus awareness if there was a radiological risk for the users or the population that lived near to it. Before performing the simulation, several measurements were made to water samples with a dynamic measurement system. This in order to know the level of radon concentration and compare the results obtained with the levels recommended by the United States Environmental Protection Agency (US-EPA) and the World Health Organization (WHO). In addition, to know if there was a radiological risk due to the presence of gamma emitting radionuclides, complementary water analyses were carried out using gamma-ray spectrometry techniques. The simulation was developed using the scientific software of particle interaction with matter, Geant4. The different variables declared for the software parameters are presented in this document. The results of the radon measurements in the water and the computational simulation, determined that there was no radiological risk due to alpha radiation. Furthermore, the results from the gamma-ray spectrometer showed that there was no presence of other hazardous radionuclides in the water.

Could the Ancestral Puebloans of Chaco Canyon, New Mexico, Have Depended on a Groundwater Ecosystem?

A thousand years ago, a population of Ancestral Puebloans occupied a high desert canyon in northwestern New Mexico, USA, where precipitation was limited and surface water scarce. Geological conditions, however, seem favorable for the production of a large Hypocrene springs system near the south canyon walls sufficient to have produced a groundwater ecosystem favorable for agriculture, tree growth, and human occupancy. A human-induced ecological impact is suggested as contributing to the dewatering of the springs, eventually reducing local agricultural production and, presumably, the suitability of Chaco Canyon for human occupancy.

Geomorphology of the Mirador-Calakmul Karst Basin: A GIS-based approach to hydrogeologic mapping.

This paper classifies the karst landscapes of the Petén Plateau and defines the Mirador-Calakmul Karst Basin by illustrating the distribution of its karst hydrologic features. Archaeological and spatial research of the Mirador-Calakmul area of Guatemala and Mexico has shown it to be a karst basin with geopolitical implications. Current research characterizes the karst landscapes of the Petén Plateau, maps the distribution of karst hydrologic features, and delineates the basin in geomorphological terms. To further this aim, multiple forms of remote sensing data including orthophotographs, a satellite Digital Elevation Model, satellite multispectral images, and Light Detection and Ranging (LiDAR) data have been integrated to interpret the karst features in the study area. Outcrop study and thin section analysis of the upper Buena Vista Formation document that the dominant lithologies are a shallow water algal boundstone interbedded with terrestrial caliche. Karst landforms have been mapped over the Petén Plateau and we identify five karst landscapes, the largest of which is a fluviokarst landscape dominated by karst valleys. We further map karst hydrologic features including seasonal swamps, dolines, intermittent lakes, intermittent streams, solution-enhanced fractures, and springs all of which are characteristic of drainage basins. Boundaries of the karst basin are mapped from multiple lines of evidence including distribution of the karst valleys, a line of springs along the western boundary of the fluviokarst landscape, and a surface drainage analysis. We capture and classify hydrologic data points and develop a regional groundwater map that indicates subsurface flow from east to west within the basin. A drainage map illustrates the extensive system of karst valleys, boundaries, and inferred groundwater flow paths of the Mirador-Calakmul Karst Basin. It was within this geomorphological setting that the ancient Maya developed an extensive civilization during the Middle and Late Preclassic periods (1000 BCE-150 CE).

Epigenetic inheritance of DNA methylation changes in fish living in hydrogen sulfide-rich springs.

Environmental factors can promote phenotypic variation through alterations in the epigenome and facilitate adaptation of an organism to the environment. Although hydrogen sulfide is toxic to most organisms, the fish Poecilia mexicana has adapted to survive in environments with high levels that exceed toxicity thresholds by orders of magnitude. Epigenetic changes in response to this environmental stressor were examined by assessing DNA methylation alterations in red blood cells, which are nucleated in fish. Males and females were sampled from sulfidic and nonsulfidic natural environments; individuals were also propagated for two generations in a nonsulfidic laboratory environment. We compared epimutations between the sexes as well as field and laboratory populations. For both the wild-caught (F0) and the laboratory-reared (F2) fish, comparing the sulfidic and nonsulfidic populations revealed evidence for significant differential DNA methylation regions (DMRs). More importantly, there was over 80% overlap in DMRs across generations, suggesting that the DMRs have stable generational inheritance in the absence of the sulfidic environment. This is an example of epigenetic generational stability after the removal of an environmental stressor. The DMR-associated genes were related to sulfur toxicity and metabolic processes. These findings suggest that adaptation of P. mexicana to sulfidic environments in southern Mexico may, in part, be promoted through epigenetic DNA methylation alterations that become stable and are inherited by subsequent generations independent of the environment.

A new genus and species of groundwater isopod of the family Protojaniridae (Isopoda: Asellota: Gnathostenetroidoidea) from southern Chile.

A new asellotan isopod of the family Protojaniridae Fresi, Idato Scipione, 1980 is described from freshwater springs in the Osorno province, Los Lagos region, southern Chile. Wiyufiloides osornoensis gen. sp. n. is the third South American protojanirid species and the first known groundwater isopod in Chile. The new genus and species is principally characterized by the presence of a vestigial antennal scale, a strongly subchelate pereiopod I and the absence of an apical lobe on the protopod of pleopod II. The new taxon is described in detail and figures are given.

Isotopic composition and hydrogeochemistry of a periglacial Andean catchment and its relevance in the knowledge of water resources in mountainous areas.

Glacial and periglacial basins contain the largest reserves of fresh water in the world. These areas are extremely sensitive to global warming and climate change. The dry Andes of South America are characterized by large periglacial areas. This study focuses on the water isotopic composition and hydrochemistry of a typical periglacial environment of the Andes, in the Vallecitos catchment (2400-5500 m a.s.l.), Cordillera Frontal, Argentina. Detailed fieldwork was conducted between 2013 and 2017 with 240 samples collected for major ions and physicochemical parameters, and 67 samples analysed for 2H and 18O. The chemical composition of precipitation is typical Ca-HCO3, while streams and groundwaters are Ca-MgSO4 type. The isotope content of precipitation shows a wide dispersion. The snow samples are in general more depleted than the rainfall. Some springs vary their composition seasonally, associated to the melting of perennial snow patches. In general, all samples from the upper basin present depleted isotope contents related to recharge at higher altitudes, whereas samples from the lower basin show more enriched values. Intermediate compositions reflect the melting of snow and degrading ice-rich permafrost. These results will give a better understanding of the dynamics of water to manage water resources.

Boletim de Monitoramento Ambiental de SARS-CoV-2 no RS (3) / SARS-Cov-2 Environmental Monitoring Bulletin in RS (3)

O estudo visa disponibilizar aos órgãos de saúde informações sobre a circulação viral nas diferentes áreas do território avaliado, aumentando a compreensão da dinâmica viral na epidemia e auxiliando na tomada de decisão das medidas de distanciamento, além de fornecer elementos que contribuam para a investigação da hipótese de transmissão fecal-oral ou fecal-respiratória. Trata-se de um projeto multicêntrico, colaborativo, que conta com a participação de pesquisadores das Universidades Feevale e UFRGS e também do serviço público nas esferas federal, estadual e municipal - representando Fundação Oswaldo Cruz - FIOCRUZ, Centro Estadual de Vigilância em Saúde - CEVS, Fundação Estadual de Proteção Ambiental - FEPAM, Departamento Municipal de Água e Esgotos- DMAE e Secretaria Municipal do Meio Ambiente e da Sustentabilidade - SMAMS de Porto Alegre e Secretaria Municipal de Saúde de Novo Hamburgo nesta primeira etapa do projeto. (AU)

Boletim de Monitoramento Ambiental de SARS-CoV-2 no RS (2) / SARS-Cov-2 Environmental Monitoring Bulletin in RS (2)

O estudo visa disponibilizar aos órgãos de saúde informações sobre a circulação viral nas diferentes áreas do território avaliado, aumentando a compreensão da dinâmica viral na epidemia e auxiliando na tomada de decisão das medidas de distanciamento, além de fornecer elementos que contribuam para a investigação da hipótese de transmissão fecal-oral ou fecal-respiratória. Trata-se de um projeto multicêntrico, colaborativo, que conta com a participação de pesquisadores das Universidades Feevale e UFRGS e também do serviço público nas esferas federal, estadual e municipal - representando Fundação Oswaldo Cruz - FIOCRUZ, Centro Estadual de Vigilância em Saúde - CEVS, Fundação Estadual de Proteção Ambiental - FEPAM, Departamento Municipal de Água e Esgotos- DMAE e Secretaria Municipal do Meio Ambiente e da Sustentabilidade - SMAMS de Porto Alegre e Secretaria Municipal de Saúde de Novo Hamburgo nesta primeira etapa do projeto. (AU)

Boletim de Monitoramento Ambiental de SARS-CoV-2 no RS (1) / SARS-Cov-2 Environmental Monitoring Bulletin in RS (1)

O estudo visa disponibilizar aos órgãos de saúde informações sobre a circulação viral nas diferentes áreas do território avaliado, aumentando a compreensão da dinâmica viral na epidemia e auxiliando na tomada de decisão das medidas de distanciamento, além de fornecer elementos que contribuam para a investigação da hipótese de transmissão fecal-oral ou fecal-respiratória. Trata-se de um projeto multicêntrico, colaborativo, que conta com a participação de pesquisadores das Universidades Feevale e UFRGS e também do serviço público nas esferas federal, estadual e municipal - representando Fundação Oswaldo Cruz - FIOCRUZ, Centro Estadual de Vigilância em Saúde - CEVS, Fundação Estadual de Proteção Ambiental - FEPAM, Departamento Municipal de Água e Esgotos- DMAE e Secretaria Municipal do Meio Ambiente e da Sustentabilidade - SMAMS de Porto Alegre e Secretaria Municipal de Saúde de Novo Hamburgo nesta primeira etapa do projeto. (AU)

Origin of spring waters employing a multiparametric approach with special focus on stable isotopes 2H and 18O in the Lagoa Santa Karst region, Southern Brazil.

Karst environments have an inherent complexity that interferes with their hydrogeology comprehension. Hence, isotope hydrology can be a valuable tool to assess trajectory of subsurface flows in an unexplored setting. The study area is located in the Lagoa Santa Karst, an environmental protection area of great economic, cultural and ecological importance, where Neoproterozoic metalimestones accommodate karst-fractured aquifers, characterized by complex water dynamics, essential vulnerability and high productivity. The purpose of this study was to investigate groundwater flow origins of springs using principally environmental stable isotopes 2H and 18O. Rainwater and spring water were sampled and analysed. The LMWL presents angular and linear coefficients strongly similar to those of the GMWL. Spring isotopic signatures, which represent the base flow and present wide-ranging of 2H and 18O, were separated into two groups. The first group can be associated with recent rainwater major contributions, while the second group shows significant evaporated water contributions, largely represented by resurgences. Tritium concentration and physico-chemical parameter data supported this interpretation, pointing that waters of the second group remained more time on the surface and subsurface. Therefore, using isotope tracers to evaluate upper groundwater zone in this tropical karst system is a powerful instrument for water resources management.

Final instar larva of Franciscagrion longispinum Machado amp; Bedê, 2015 (Odonata: Coenagrionidae), an endemic species from the springs of the São Francisco river.

Franciscagrion longispinum Machado Bedê larvae were collected in the São Francisco river historical springs at the Serra da Canastra National Park, Brazil. Here, we describe and illustrate the final instar larvae of this rare and endemic species.

Molecular and morphological convergence to sulfide-tolerant fishes in a new species of Jenynsia (Cyprinodontiformes: Anablepidae), the first extremophile member of the family.

Freshwater sulfide springs have extreme environmental conditions that only few vertebrate species can tolerate. These species often develop a series of morphological and molecular adaptations to cope with the challenges of life under the toxic and hypoxic conditions of sulfide springs. In this paper, we described a new fish species of the genus Jenynsia, Anablepidae, from a sulfide spring in Northwestern Argentina, the first in the family known from such extreme environment. Jenynsia sulfurica n. sp. is diagnosable by the lack of scales on the pre-pelvic area or the presence of a single row of scales, continuous or not, from the isthmus to the bases of the pelvic fins. Additionally, it presents a series of morphological and molecular characteristics that appear convergent with those seen in other fish species (e.g., Poeciliids) inhabiting sulfide springs. Most notably, J. sulfurica has an enlarged head and postorbital area compared to other fish of the genus and a prognathous lower jaw with a hypertrophied lip, thought to facilitate respiration at the air-water interface. Analyses of cox1 sequence showed that J. sulfurica has two unique mutations resulting in amino acid substitutions convergent to those seen in Poeciliids from sulfide springs and known to provide a physiological mechanism related to living in sulfide environments. A phylogenetic analysis, including molecular and morphological characters, placed J. sulfurica as sister taxa to J. alternimaculata, a species found in nearby, non-sulfide habitats directly connected to the sulfide springs. Thus, it can be inferred that the selection imposed by the presence of H2S has resulted in the divergence between these two species and has potentially served as a barrier to gene flow.

Hydrogeological responses in tropical mountainous springs.

This study presents a hydrogeochemical analysis of spring responses (2013-2017) in the tropical mountainous region of the Central Valley of Costa Rica. The isotopic distribution of δ18O and δ2H in rainfall resulted in a highly significant meteoric water line: δ2H = 7.93·Î´18O + 10.37 (r2 = 0.97). Rainfall isotopic composition exhibited a strong amount-dependent seasonality. The isotopic variation (δ18O) of two springs within the Barva aquifer was simulated using the FlowPC program to determine mean transit times (MTTs). Exponential-piston and dispersion distribution functions provided the best-fit to the observed isotopic composition at Flores and Sacramento springs, respectively. MTTs corresponded to 1.23 ± 0.03 (Sacramento) and 1.42 ± 0.04 (Flores) years. The greater MTT was represented by a homogeneous geochemical composition at Flores, whereas the smaller MTT at Sacramento is reflected in a more variable geochemical response. The results may be used to enhance modelling efforts in central Costa Rica, whereby scarcity of long-term data limits water resources management plans.

Determination of pesticides in the source and drinking waters in Londrina, Paraná, Brazil / Determinação de agrotóxicos em água de manancial e água de abastecimento público em Londrina, Paraná, Brasil

The Brazilian agricultural model is based on the intensive use of pesticides. Once in the environment, these compounds might target hydric sources, mainly through soil lixiviation or during crop application, exposing water biota as well as humans to contaminants. The objective of this research was identify the presence of 14 pesticides (ametrine, atrazine, azoxystrobin, carbendazim, carbofuran, clomazone, chlorpirifos, diuron, hexazinone, imidacloprid, malathion, simazine, tebuconazole and tebuthiuron) in source water samples and drinking water samples from the city of Londrina, Paraná State, Brazil. 24 water samples were collected biweekly from December 2014 to October 2015. The sample preparation was done using Solid Phase Extraction (SPE) with 3 mL/500 mg C-18 cartridges. Pesticide determination was performed applying Liquid Chromatography tandem Mass Spectrometry (LC-MS/MS). The frequencies of detection of some compounds in source water were: atrazine (85%), azoxystrobin (95%), carbendazim (83%), diuron (75%), imidacloprid (95%), simazine (12%), hexazinone (4%), tebutiuron (4%) and tebuconazole (33%). In the water supply, the following were detected: atrazine (79%), azoxystrobin (95%), carbendazim (8%), diuron (83%), imidacloprid (95%), simazine (12%), hexazinone (4%), tebuthiuron (8%) and tebuconazole (33%). Some of these compounds are included in Brazilian legislation, and in these cases, the concentrations determined in this study varied between 241 and 7 ng Lˉ¹, which were lower than the maximum allowable concentrations for each of the compounds.

O modelo de agricultura brasileiro é baseado no uso intensivo de agrotóxicos. Uma vez no ambiente, estes compostos podem atingir recursos hídricos, principalmente através da lixiviação ou durante a aplicação, expondo a biota aquática e até mesmo humanos, aos contaminantes. O objetivo deste trabalho foi identificar a presença dos agrotóxicos ametrina, atrazina, azoxistrobina, carbendazim, carbofurano, clomazona, clorpirifós, diuron, hexazinona, imidacloprido, malation, simazina, tebuconazol e tebutiuron em amostras de água de manancial e de abastecimento público da cidade de Londrina, Paraná, Brasil. Foram coletadas 24 amostras, quinzenalmente, de Dezembro de 2014 a Outubro de 2015. Para o preparo das amostras foi utilizado Extração em Fase Sólida (SPE) com cartuchos de 3 mL C-18 de 500 mg. A determinação de agrotóxicos foi realizada utilizando Cromatografia Líquida acoplada à Espectrometria de Massas (LC-MS/MS). Nas amostras do manancial, foram detectados os compostos atrazina (85%), azoxistrobina (95%), carbendazin (83%), diuron (75%), imidacloprido (95%), simazina (12%), hexazinona (4%), tebutiuron (8%) e tebuconazol (33%). Nas amostras de água para abastecimento público, foram detectados atrazina (79%), azoxistrobina (95%), carbendazim (8%), diuron (83%), imidacloprido (95%), simazina (12%), hexazinona (4%), tebutiuron (8%) e tebuconazol (33%). Alguns destes compostos estão inseridos na legislação brasileira e nestes casos, as concentrações determinadas neste estudo variaram entre 241 e 7 ng L-1, as quais foram inferiores às máximas concentrações determinadas para cada um dos compostos.

Determination of pesticides in the source and drinking waters in Londrina, Paraná, Brazil / Determinação de agrotóxicos em água de manancial e água de abastecimento público em Londrina, Paraná, Brasil

The Brazilian agricultural model is based on the intensive use of pesticides. Once in the environment, these compounds might target hydric sources, mainly through soil lixiviation or during crop application, exposing water biota as well as humans to contaminants. The objective of this research was identify the presence of 14 pesticides (ametrine, atrazine, azoxystrobin, carbendazim, carbofuran, clomazone, chlorpirifos, diuron, hexazinone, imidacloprid, malathion, simazine, tebuconazole and tebuthiuron) in source water samples and drinking water samples from the city of Londrina, Paraná State, Brazil. 24 water samples were collected biweekly from December 2014 to October 2015. The sample preparation was done using Solid Phase Extraction (SPE) with 3 mL/500 mg C-18 cartridges. Pesticide determination was performed applying Liquid Chromatography tandem Mass Spectrometry (LC-MS/MS). The frequencies of detection of some compounds in source water were: atrazine (85%), azoxystrobin (95%), carbendazim (83%), diuron (75%), imidacloprid (95%), simazine (12%), hexazinone (4%), tebutiuron (4%) and tebuconazole (33%). In the water supply, the following were detected: atrazine (79%), azoxystrobin (95%), carbendazim (8%), diuron (83%), imidacloprid (95%), simazine (12%), hexazinone (4%), tebuthiuron (8%) and tebuconazole (33%). Some of these compounds are included in Brazilian legislation, and in these cases, the concentrations determined in this study varied between 241 and 7 ng Lˉ¹, which were lower than the maximum allowable concentrations for each of the compounds.(AU)

O modelo de agricultura brasileiro é baseado no uso intensivo de agrotóxicos. Uma vez no ambiente, estes compostos podem atingir recursos hídricos, principalmente através da lixiviação ou durante a aplicação, expondo a biota aquática e até mesmo humanos, aos contaminantes. O objetivo deste trabalho foi identificar a presença dos agrotóxicos ametrina, atrazina, azoxistrobina, carbendazim, carbofurano, clomazona, clorpirifós, diuron, hexazinona, imidacloprido, malation, simazina, tebuconazol e tebutiuron em amostras de água de manancial e de abastecimento público da cidade de Londrina, Paraná, Brasil. Foram coletadas 24 amostras, quinzenalmente, de Dezembro de 2014 a Outubro de 2015. Para o preparo das amostras foi utilizado Extração em Fase Sólida (SPE) com cartuchos de 3 mL C-18 de 500 mg. A determinação de agrotóxicos foi realizada utilizando Cromatografia Líquida acoplada à Espectrometria de Massas (LC-MS/MS). Nas amostras do manancial, foram detectados os compostos atrazina (85%), azoxistrobina (95%), carbendazin (83%), diuron (75%), imidacloprido (95%), simazina (12%), hexazinona (4%), tebutiuron (8%) e tebuconazol (33%). Nas amostras de água para abastecimento público, foram detectados atrazina (79%), azoxistrobina (95%), carbendazim (8%), diuron (83%), imidacloprido (95%), simazina (12%), hexazinona (4%), tebutiuron (8%) e tebuconazol (33%). Alguns destes compostos estão inseridos na legislação brasileira e nestes casos, as concentrações determinadas neste estudo variaram entre 241 e 7 ng L-1, as quais foram inferiores às máximas concentrações determinadas para cada um dos compostos.(AU)

Certain species of Plecoptera from the headwater springs of National Integration River (São Francisco), Brazil.

Specimens of Anacroneuria Klapálek 1909 (Plecoptera: Perlidae) and Tupiperla Froehlich 1969 (Plecoptera: Gripopterygidae) from the headwater springs of the National Integration River (São Francisco River), Serra da Canastra National Park, in Minas Gerais State, of southeastern Brazil, were studied. A new species, Anacroneuria saofrancisco n. sp. is described and the descriptions of the nymph and the female of A. saofrancisco are also presented.

DETERMINATION AND DOSE CONTRIBUTION OF URANIUM ISOTOPES AND 210Po ACTIVITY CONCENTRATIONS OF NATURAL SPRING WATERS IN THE PROVINCE OF GRANADA, SPAIN.

The activity concentrations of alpha-emitters comprising isotopes of uranium (238, 234, 235U) and polonium (210Po) were measured using alpha-particle spectrometry in natural spring waters in the province of Granada, Spain. These water are consumed by the population of the zone who live in villages. This is almost half of the population of the whole region. Mean values of activity concentrations found are 42.61 ± 2.66; 49.55 ± 3.03; 1.64 ± 0.28 and 1.74 ± 0.15 mBq L-1 for 238U, 234U, 235U and 210Po, respectively. Finally, the radiological impact of the analysed waters has been determined, in terms of the estimation of the committed annual effective dose due to the ingestion of the water. The assessment has been carried out for five age groups with the aim to cover all the population. The calculated annual effective doses are observed to be below the prescribed dose limit of 100 µSv y-1 recommended by WHO.

Extreme environments and the origins of biodiversity: Adaptation and speciation in sulphide spring fishes.

Organisms adapted to physiochemical stressors provide ideal systems to study evolutionary mechanisms that drive adaptation and speciation. This review study focuses on livebearing fishes of the Poecilia mexicana species complex (Poeciliidae), members of which have repeatedly colonized hydrogen sulphide (H2 S)-rich springs. H2 S is a potent respiratory toxicant that creates extreme environmental conditions in aquatic ecosystems. There is also a rich history of research on H2 S in toxicology and biomedicine, which has facilitated the generation of a priori hypotheses about the proximate mechanisms of adaptation. Testing these hypotheses through the application of high-throughput genomic and transcriptomic analyses has led to the identification of the physiological underpinnings mediating adaptation to H2 S-rich environments. In addition, systematic natural history studies have provided a nuanced understanding of how the presence of a physiochemical stressor interacts with other sources of selection to drive evolutionary change in a variety of organismal traits, including physiology, morphology, behaviour and life history. Adaptation to extreme environments in P. mexicana also coincides with ecological speciation, and evolutionarily independent lineages span almost the full range of the speciation continuum from panmixia to complete reproductive isolation. Multiple mechanisms of reproductive isolation are involved in reducing gene flow between adjacent populations that are adapted to contrasting environmental conditions. Comparative studies among evolutionarily independent lineages within the P. mexicana species complex and, more recently, other members of the family Poeciliidae that have colonized H2 S-rich environments will provide insights into the factors facilitating or impeding convergent evolution, providing tangible links between micro-evolutionary processes and macro-evolutionary patterns.