Impacts of subsurface biogeochemical processes over time have always been a concern for the long-term performance of zero valent iron (Fe⁰)-based permeable reactive barriers (PRBs). To evaluate the biogeochemical impacts, laboratory experiments were performed using flow-through glass columns for 210 days at controlled temperature (20 °C). Two different particle sizes of Fe⁰ were used in the columns, and to simulate indigenous microbial activity, extra carbon source was provided in the two columns (biotic columns) and the remaining two columns were kept abiotic using gamma radiations. Heavy metals (Zn, As) were removed efficiently in all the columns, and no exhaustion of treatment capability or clogging was observed during our experimental duration. Newly formed Fe mineral phases and precipitates were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and micro-XRF techniques in solid phase at the end of the experiment. In addition, 16S rRNA gene extraction was used for microbial community identification in biotic columns. During the incubation, microbial population shifted in favor of Desulfosporosinus species (sulfate-reducing bacteria) from initial dominance of Acidithiobacillus ferrooxidans in sediments. Dominant mineral phases detected in biotic columns were mackinawite (FeS) and sulfate green rust, while in abiotic columns, magnetite/maghemite phases were more prevalent.

International audience | Impacts of subsurface biogeochemical processes over time have always been a concern for the long-term performance of zero valent iron (Fe0) based Permeable Reactive Barriers (PRB’s). To evaluate the biogeochemical impacts, laboratory experiments were performed using flow-through glass columns for 210 days at controlled temperature (20 °C). Two different particle size of Fe0 were used in the columns, and to simulate indigenous microbial activity, extra carbon source was provided in two columns (biotic columns) and remaining two columns were kept abiotic. Heavy metals (Zn, As) were removed efficiently in all the columns, and no exhaustion of treatment capability or clogging were observed during our experimental duration. Newly formed Fe- mineral phases and precipitates were characterized using XRD, SEM-EDX and micro-XRF techniques in solid phase at the end of the experiment. In addition, 16S rRNA gene extraction was used for microbial community identification in biotic columns. During the incubation, microbial population shifted in favour of Desulforsporosinus species (sulfate-reducing bacteria) from initial dominance of Acidithiobacillus ferrooxidans in sediments. Dominant mineral phases detected in biotic columns were mackinawite (FeS) and sulfate green-rust while in abiotic columns magnetite/maghemite phases were more prevalent.

The aim of this 2-year study was to examine the temporal changes in the concentration of microbiological indicators of water contamination and selected physicochemical parameters within the Białka river and its selected tributaries in the vicinity of the largest ski station in Białka Tatrzańska. The study involved 24 series of sampling in eight sites throughout the Białka river and on its selected tributaries. Temperature, pH, and electrical conductivity (EC₂₅ °C) were measured onsite. The microbiological assays included the numbers of mesophilic and psychrophilic bacteria, Staphylococcus spp. and Salmonella spp., as well as coliforms, thermotolerant (fecal) coliforms, Escherichia coli, Enterococcus faecalis, and sulfate-reducing Clostridium. The chemical analyses were conducted to determine the concentration of NH₄ ⁺, NO₂ ⁻, NO₃ ⁻, and PO₄ ³⁻. The analyses showed that contrary to common opinion, waters of the Białka river are strongly polluted in some sections. Seasonal variation in the prevalence of microbial indicators of fecal pollution was found, and the largest numbers of microorganisms were observed in winter ski season, followed by summer holidays. Similar seasonal pattern was observed in the examined chemical parameters. There was also very strong spatial variation within the tested microbial and chemical parameters, indicating the presence of pollution hotspots in the course of the Białka river. The employed principal component analysis revealed the presence of two main pollution sources, mainly affecting the quality of river water, i.e., fecal contamination of human origin and the natural source in the form of surface runoff and soil leaching. These factors, depending on the location of the sampling site, occurred in different configurations.

The aim of this 2-year study was to examine the temporal changes in the concentration of microbiological indicators of water contamination and selected physicochemical parameters within the Białka river and its selected tributaries in the vicinity of the largest ski station in Białka Tatrzańska. The study involved 24 series of sampling in eight sites throughout the Białka river and on its selected tributaries. Temperature, pH, and electrical conductivity (EC25 °C) were measured onsite. The microbiological assays included the numbers of mesophilic and psychrophilic bacteria, Staphylococcus spp. and Salmonella spp., as well as coliforms, thermotolerant (fecal) coliforms, Escherichia coli, Enterococcus faecalis, and sulfate-reducing Clostridium. The chemical analyses were conducted to determine the concentration of NH4+, NO2−, NO3−, and PO43−. The analyses showed that contrary to common opinion, waters of the Białka river are strongly polluted in some sections. Seasonal variation in the prevalence of microbial indicators of fecal pollution was found, and the largest numbers of microorganisms were observed in winter ski season, followed by summer holidays. Similar seasonal pattern was observed in the examined chemical parameters. There was also very strong spatial variation within the tested microbial and chemical parameters, indicating the presence of pollution hotspots in the course of the Białka river. The employed principal component analysis revealed the presence of two main pollution sources, mainly affecting the quality of river water, i.e., fecal contamination of human origin and the natural source in the form of surface runoff and soil leaching. These factors, depending on the location of the sampling site, occurred in different configurations. | Białka river, Spatiotemporal variability, Microbiological quality, Fecal contamination, Nutrients, Principal component analysis | 25 | 1-12 | 1

An in situ post tsunami study was conducted to assess the effect of water management and rainfalls in soil properties and water quality at a low-lying coastal area of central Chile affected by Mw8.8 Earthquake Tsunami the night of 27 February 2010. Soil samples were taken at two depths (0 to 20 and 20 to 40 cm) during 2010 and late 2012. Water quality in a local shallow well was also monitored in 2010 and 2012. High soil salinity was recorded 2 months later than tsunami occurs, closely associated to water-soluble chloride and cations (Cl⁻ > > Na⁺ > > Ca²⁺ > Mg²⁺ > K⁺), ionic toxicities, and vegetal inhibition (Vasconcellea pubescens) by less available water to plants. An initial reduction in soil pH due to ionic strength and coarse-textured class of soil was observed and the sodium adsorption ratio (SAR) in soil varied between 5.7 and 11.2 (mmol L⁻¹)⁰.⁵ showing to be saline. Although SARw values are very high (>18 (mmol L⁻¹)⁰.⁵), it does not exist risks of reduction on soil infiltration rates according to ECw (>5 dS m⁻¹) obtained. After 2 years, soil salinity was drastically reduced in the affected areas due to high soil permeability and natural attenuation (rainfalls and leaching effects), with sulfate and bicarbonate concentrations showing excessive values. Further, irrigation water quality returned to pre-tsunami situation, with only levels of sodium slightly exceeding desirable range from health point of view. Finally, it is suggested a proper design of irrigation systems before implementing other management practices.

An in situ post tsunami study was conducted to assess the effect of water management and rainfalls in soil properties and water quality at a low-lying coastal area of central Chile affected by Mw8.8 Earthquake Tsunami the night of 27 February 2010. Soil samples were taken at two depths (0 to 20 and 20 to 40 cm) during 2010 and late 2012. Water quality in a local shallow well was also monitored in 2010 and 2012. High soil salinity was recorded 2 months later than tsunami occurs, closely associated to water-soluble chloride and cations (Cl- >> Na+ >> Ca2+> Mg2+> K+), ionic toxicities, and vegetal inhibition (Vasconcellea pubescens) by less available water to plants. An initial reduction in soil pH due to ionic strength and coarse-textured class of soil was observed and the sodium adsorption ratio (SAR) in soil varied between 5.7 and 11.2 (mmol L-1)(0.5) showing to be saline. Although SARw values are very high (> 18 (mmol L-1) 0.5), it does not exist risks of reduction on soil infiltration rates according to ECw (> 5 dS m(-1)) obtained. After 2 years, soil salinity was drastically reduced in the affected areas due to high soil permeability and natural attenuation (rainfalls and leaching effects), with sulfate and bicarbonate concentrations showing excessive values. Further, irrigation water quality returned to pre-tsunami situation, with only levels of sodium slightly exceeding desirable range from health point of view. Finally, it is suggested a proper design of irrigation systems before implementing other management practices