CO₂/³He ratios reveal the presence of mantle gas in the CO₂-rich groundwaters of the Ardenne massif (Spa, Belgium)

Natural CO2-rich groundwaters of eastern Belgium have been known for centuries although the exact origin of the gas they contained was still unclear. This paper presents the results of a sampling campaign in the area (Spa, Stoumont, Malmedy) where 30 samples of both carbogazeous and non-carbogazeous groundwaters have been analyzed for major elements, CO2 content and carbon isotopic composition. Among them, 13 samples were analyzed for 3He / 4He and 4He / 20Ne ratios. The combination of δ13C and 3He / CO2 ratios have shown with a high level of confidence that the CO2 in groundwater from springs and boreholes has a mantellic origin, and can very likely be attributed to the degassing of the neighboring and still buoyant Eifel mantle plume, located at a distance of 100 km eastwards. The identity and nature of the deep-rooted fractures that act as CO2 transport pathway to the surface are still to be clarified, but several major thrust faults exist in the Rhenish Massif and could connect the Eifel volcanic field with the studied area.

Environmental implications of fluoride presence in drinking water along the southeastern of El Bajío Guanajuatese, Guanajuato, Mexico: sources and health effects

Chronic exposure from drinking water with naturally high concentrations of fluoride (F⁻) has serious health consequences in several regions across the world including north-central Mexico as Guanajuato State, where the rural population is particularly dependent on untreated groundwater pumped from wells that have natural F- concentrations higher than those allowed by national and international regulations. The contaminated aquifers in the area are usually located in fractured volcanic environment that interacts with sedimentary basins and have a carbonate basement. Few studies focused on identifying the origin and hydrogeochemical processes related to fluoride release and mobilization have been developed, and even fewer that quantify the natural content of F in the geological environment. In this study, an evaluation of fluoride in volcanic rocks collected from 11 sampling sites along the Sierra de Codornices (Guanajuato State, Central Mexico) was carried out. The fluoride content is disseminated in volcanic rocks and the highest contents were obtained in felsic rocks. According to results obtained of a sampling campaign of 32 wells in 2019 their statistical and hydrogeochemical evaluation suggest that F- mobilization in groundwater from Juventino Rosas and Villagran municipalities, is a product of volcanic glass dissolution, a process involved in alkaline desorption occurring on the surfaces of F-containing minerals, and possibly on ion exchange occurring in minerals and some clays or even in deep fluids enriched in F. All these processes may be accelerated by the geothermal characteristics of the groundwater in the study area. The hydrogeochemical results and the epidemiological survey conducted indicate that children and older adults of Praderas de la Venta are at risk of exposure to F- due to the high concentrations ingested over a long period of time, to the toxicity of the element and its ability to accumulate in the bones. Prolonged exposure to high concentrations increases the risk.

High concentrations of pharmaceuticals emerging as a threat to Himalayan water sustainability

The sixth UN Sustainable Development Goal, Clean Water and Sanitation, directly underpins other goals of Health, Life in Water and Sustainable Cities. We highlight that poor sanitation, exemplified through some of the highest concentrations of pharmaceuticals ever detected in rivers, will amplify societal and environmental stress where climate-induced reductions in flow are predicted. Rapidly growing urban centres with inadequate water treatment works will need to prioritise water quality improvement before supply reductions become a reality. For 23 river locations within Kathmandu City and the Annapurna region, Nepal, we show the presence of 28 of 35 monitored human-use pharmaceuticals. Concentrations of antibiotics measured in this sampling campaign in both Kathmandu City (sulfamethazine, metronidazole and ciprofloxacin) and rural locations (ciprofloxacin) are in excess of predicted no effect concentrations, suggesting these sites are at risk of proliferating antimicrobial resistance as well as affecting other ecotoxicological endpoints. It is anticipated that climate-induced reductions in flow combined with contaminated river systems will amplify future societal and environmental stress.

A Heritage Agronomic Study as a Database for Monitoring the Soil Salinity of an Irrigated District in NE Spain

This article presents and reviews the soil salinity data provided by a rescued vintage agronomic report on an irrigated area of 35,875 ha located in the center of the Ebro River basin, in the NE of mainland Spain. These data come from a soil sampling campaign conducted from May to the first half of July 1975 for the purpose of delineating saline and non-saline soils. The agronomic report was produced in response to demands from farmers to combat soil salinity, and represents the state of the art in those years for salinity studies. Our paper presents the scrubbed soil salinity data for this year, checking their consistency and locating the study sites. The main finding is the unearthing of this heritage report and the discussion of its soil salinity data. We show that the report supplies an assessment and a baseline for further soil salinity tracking by conducting new measurements either by direct soil sampling or by nondestructive techniques, providing an estimate of soil salinity at different locations. This task is feasible, as shown in our previously published articles involving nearby areas. A comparison of the salt amount in the soil over the years would provide a means to evaluate irrigation methods for sustainable land management. This comparison can be conducted simultaneously with analysis of other agricultural features described in the report for the irrigation district in 1975.

Net heterotrophy in High Arctic first-year and multi-year spring sea ice

The net productivity of sea ice is determined by the physical and geochemical characteristics of the ice–ocean system and the activity of organisms inhabiting the ice. Differences in habitat suitability between first-year and multi-year sea ice can affect the ice algal community composition and acclimation state, introducing considerable variability to primary production within each ice type. In this study, we characterized the biogeochemical variability between adjacent first-year and multi-year sea ice floes in the Lincoln Sea of the Canadian High Arctic, during the May 2018 Multidisciplinary Arctic Program—Last Ice sampling campaign. Combining measurements of transmitted irradiance from a remotely operated underwater vehicle with laboratory-based oxygen optode incubations, this work shows widespread heterotrophy (net oxygen uptake) in the bottom 10 cm of both ice types, particularly in thick multi-year ice (>2.4 m) and early morning of the 24-h day. Algal acclimation state and species composition varied between ice types despite similar net community production due to widespread light and nutrient limitation. The first-year ice algal community was increasingly dominated over spring by the potentially toxin-producing genus Pseudonitzschia that was acclimated to high and variable light conditions characteristic of a thinner ice habitat with mobile snow cover. In comparison, the multi-year ice harbored more shade-acclimated algae of mixed composition. This work highlights the potential for heterotrophy in sea ice habitats of the High Arctic, including first measurements of such O2-uptake in multi-year ice floes. Observed differences in photophysiology between algae of these sea ice types suggests that a shift toward higher light availability and a younger sea ice cover with climate change does not necessarily result in a more productive system. Instead, it may favor future sea ice algal communities of different species composition, with lower photosynthetic potential but greater resilience to stronger and more variable light conditions.

ORGANIC POLLUTION INDEX IN THE EVALUATION OF THE QUALITY OF LAKE DOHOU, A SOURCE OF DRINKING WATER SUPPLY IN THE CITY OF DUEKOUE (WEST COTE DIVOIRE)

The abiotic typology of the different sampling stations based on physico-chemical parameters and the assessment of the nutrient load and the relative contributions of the different nutrient sources to this surface water were analysed. Five physical and chemical parameters (temperature, dissolved oxygen, transparency, pH and conductivity) were measured in situ at each sampling campaign in Lake Dohou over a period of one year, once a month at seven (7) selected stations. Water samples were taken for subsequent determination of dissolved solids, biological oxygen demand for 5 days and nutrient salts (nitrite, nitrate, phosphate, ammonium).Thephysico-chemical characterisation revealed weakly mineralised water with average conductivities varying from 12.38 ±16.33 µS.cm-1 to 39.63 ±45.28 µS.cm-1 with high temperatures in the dry season. A hierarchical ascending classification (HAC) was used to group the stations into 3 groups. Group I (stations 6), due to its exposure to domestic discharges and leaching from agricultural land, is heavily loaded with organic matter and nutrients. The values of the pollution index express a high organic pollution at all the sampling stations. The water of Lake Dohou is highly loaded with organic matter and receives a very high amount of pollutant from the environment.

Using Passive Samplers to Track per and Polyfluoroalkyl Substances (PFAS) Emissions From the Paper Industry: Laboratory Calibration and Field Verification

Per and polyfluoroalkyl substances (PFAS) are becoming more stringently regulated and as such, a more diverse suite of environmental monitoring methods is needed. In this work a polar organic chemical integrative sampler (POCIS) with a nylon membrane and a combination of Oasis WAX and Fluoroflash® sorbents was calibrated in the laboratory and deployed in the field. A static renewal system was used to determine sampling rates for 12 PFAS which ranged between 0.69 ± 0.27 to 5.68 ± 1.80 L/day. POCIS devices were deployed for 10 days in lake Tyrifjorden, Norway which is known to be contaminated by a closed down factory producing paper products, in order to track the evolution of the PFAS contamination in a river system draining into the lake. Th sampling campaign enabled the stretch of the river which was responsible for the emissions of PFAS to lake Tyrifjorden to be identified. Freely dissolved concentrations determined with the POCIS were lowest at the site considered to reflect a diffuse PFAS contamination and highest at the site located downstream the factory. Perfluorooctanesulfonic acid (PFOS), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonamidoacetic acid (EtFOSAA) dominated the concentration profile at this site. Emissions of PFAS to lake Tyrifjorden were estimated to be 3.96 g/day for the sum of the 12 investigated PFAS.

Annual exposure to polycyclic aromatic hydrocarbons in urban environments linked to wintertime wood-burning episodes

Polycyclic aromatic hydrocarbons (PAHs) are organic pollutants in fine particulate matter (PM) long known to have mutagenic and carcinogenic effects, but much is unknown about the importance of local and remote sources for PAH levels observed in population-dense urban environments. A year-long sampling campaign in Athens, Greece, where more than 150 samples were analyzed for 31 PAHs and a wide range of chemical markers, was combined with positive matrix factorization (PMF) to constrain the temporal variability, sources, and carcinogenic risk associated with PAHs. It was found that biomass burning (BB), a source mostly present during wintertime intense pollution events (observed for 18 % of measurement days in 2017), led to wintertime PAH levels that were 7 times higher than in other seasons and was as important for annual mean PAH concentrations (31 %) as diesel and oil (33 %) and gasoline (29 %) sources. The contribution of non-local sources, although limited on an annual basis (7 %), increased during summer, becoming comparable to that of local sources combined. The fraction of PAHs (12 members that were included in the PMF analysis) that was associated with BB was also linked to increased health risk compared to the other sources, accounting for almost half the annual PAH carcinogenic potential (43 %). This can result in a large number of excess cancer cases due to BB-related high PM levels and urges immediate action to reduce residential BB emissions in urban areas facing similar issues.

Airborne environmental DNA metabarcoding detects more diversity, with less sampling effort, than a traditional plant community survey

Background Airborne environmental DNA (eDNA) research is an emerging field that focuses on the detection of species from their genetic remnants in the air. The majority of studies into airborne eDNA of plants has until now either focused on single species detection, specifically only pollen, or human health impacts, with no previous studies surveying an entire plant community through metabarcoding. We therefore conducted an airborne eDNA metabarcoding survey and compared the results to a traditional plant community survey. Results Over the course of a year, we conducted two traditional transect-based visual plant surveys alongside an airborne eDNA sampling campaign on a short-grass rangeland. We found that airborne eDNA detected more species than the traditional surveying method, although the types of species detected varied based on the method used. Airborne eDNA detected more grasses and forbs with less showy flowers, while the traditional method detected fewer grasses but also detected rarer forbs with large showy flowers. Additionally, we found the airborne eDNA metabarcoding survey required less sampling effort in terms of the time needed to conduct a survey and was able to detect more invasive species than the traditional method. Conclusions Overall, we have demonstrated that airborne eDNA can act as a sensitive and efficient plant community surveying method. Airborne eDNA surveillance has the potential to revolutionize the way plant communities are monitored in general, track changes in plant communities due to climate change and disturbances, and assist with the monitoring of invasive and endangered species.

News from the western front: occurrence of Mediterranea depressa (Sterki, 1880) (Mollusca: Gastropoda: Oxychilidae) in the Vosges and Jura Mountains (north-eastern France)

We report here the first record of Mediterranea depressa (Sterki, 1880) in the north-eastern quarter of France, in the Vosges and Jura massifs. After the fortuitous discovery of some shells attributed to M. depressa in the southern Vosges Mts., an extensive sampling campaign was carried out both in the Vosges and in the Jura Mts. In total, about 20 shells and seven live specimens were found at eight localities, which, according to the present state of our knowledge, represent its north-western range limit. The species was found exclusively under stones of rocky slope screes on siliceous and calcareous substrates. Some of these habitats could be described as Mesovoid Shallow Substratum. It is not clear whether the rarity of the species is an effect of under-sampling or of its small size and unusual habitat or/and to intrinsic rarity due to isolated populations at the distribution limits of the species. The extreme north-eastern quarter of France constitutes an oceanic-continental transition zone where about thirty gastropod species from Central and Eastern Europe are currently documented at the western limit of their ranges.