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The antiviral drug ribavirin is widely used and continuously released into the environment through various pathways, which will cause serious water pollution and virus resistance. However, only few works have examined ribavirin retention and transport groundwater environment. This study investigates the transport behavior of ribavirin in saturated quartz sand and limestone porous media, considering ionic strength (IS), ionic type and humic acid (HA), through column experiments and mathematical modeling. The findings reveal that, ribavirin exhibits strong mobility within saturated quartz sand media is less affected by different hydrochemical factors, posing a high risk of migration. In limestone porous media, the migration of ribavirin decreased. In comparison to Na+, the presence of Ca2+ causes the effluent recovery rate of ribavirin decreases. And as the IS of Ca2+ background solution increases, the effluent recovery rate of ribavirin also decreases. The presence of HA causes more ribavirin to flow out of the column, and its effect becomes more pronounced with increasing concentration. Furthermore, simulated precipitation scenarios, the ribavirin adsorbed on the of media surface is released again and transport with the water flow. These findings enhance our understanding about the environmental fate of ribavirin and facilitating ecological restoration efforts.

Cellulose nanofibrils, CNFs, show great potential in many application areas. One main aspect limiting the industrial use is the slow and energy demanding dewatering of CNF suspensions. Here we investigate the dewatering with a piston press process. Three different CNF grades were dewatered to solid contents between approx. 20 and 30%. The CNF grades varied in charge density (30, 106 and 604 µmol/g) and fibrillation degree. The chemical conditions were varied by changing salt concentration (NaCl) and pH and the dewatering rates were compared before and after these changes. For the original suspensions, a higher charge provides slower dewatering with the substantially slowest dewatering for the highest charged CNFs. However, by changing the conditions it dewatered as fast as the two lower charged CNFs, even though the salt/acid additions also improved the dewatering rate for these two CNFs. Finally, by tuning the conditions, fast dewatering could be obtained with only minor effect on film properties (strength and oxygen barrier) produced from redispersed dispersion. However, dewatering gives some reduction in viscosity of the redispersed dispersions. This may be a disadvantage if the CNF application is as e.g. rheology modifier or emulsion stabilizer. Graphical abstract

Background Bacteriophage survives in at least two extremes of ionic environments: bacterial host (high ionic - cytosol ) and that of soil ( low ionic - environmental water ). The impact of ionic composition in the micro- and macro-environments has not so far been addressed in phage biology. Results Here, we discovered a novel mechanism of aggregation/disaggregation transitions by phage virions. When normal sodium levels in phage media (150 mM) were lowered to 10 mM, advanced imaging by scanning electron microscopy, atomic force microscopy and dynamic light scattering all revealed formation of viral packages, each containing 20–100 virions. When ionic strength was returned from low to high, the aggregated state of phage reversed to a dispersed state, and the change in ionic strength did not substantially affect infectivity of the phage. By providing the direct evidence, that lowering of the sodium ion below the threshold of 20 mM causes rapid aggregation of phage while returning Na + concentration to the values above this threshold causes dispersion of phage, we identified a biophysical mechanism of phage aggregation. Conclusions Our results implicate operation of group behavior in phage and suggest a new kind of quorum sensing among its virions that is mediated by ions. Loss of ionic strength may act as a trigger in an evolutionary mechanism to improve the survival of bacteriophage by stimulating aggregation of phage when outside a bacterial host. Reversal of phage aggregation is also a promising breakthrough in biotechnological applications, since we demonstrated here the ability to retain viable virion aggregates on standard micro-filters.

Functionalized multiwalled carbon nanotube (f-MWCNT) mixed matrix forward osmosis (FO) membranes were fabricated by phase inversion, and the mechanism of sodium alginate (SA) membrane fouling in the presence of various inorganic components with high ionic strength was thoroughly investigated. The membrane incorporated with 0.5% f-MWCNTs (M-0.5) exhibited enhanced performance, which was attributed to the hydrophilicity of the modified nanoparticles and their good compatibility with the cellulose acetate (CA) substrate. Moreover, it was found that the initial permeate flux decline rate for all FO membranes investigated followed the order Na + + Ca 2+ + Mg 2+ > Na + + Ca 2+ > Na + + Mg 2+ > Na + , which was attributed to the particle size of SA macromolecules in the corresponding solutions. However, the gradual change in attenuation was consistent with adhesion force observations made for the SA-fouled FO membrane in the later steady-state stage, and there was little difference among M-0 (without f-MWCNTs), M-0.5, and M-1 (with 1% f-MWCNTs). Furthermore, the SA adsorption layer was most compact in the presence of Ca 2+ , and the flux recovery rate (FRR) was the lowest after simple hydraulic cleaning, but the overall FRRs for FO membranes were greater than 85%. This implies that although a decrease in electrostatic repulsion leads to the formation of a compact fouling layer, an increase in hydration repulsion of hydrated salt ions plays a major role in membrane fouling under high ionic strength conditions. Graphical abstract

Currently, the concept of a double electric layer in soil colloids is often used to explain the effect of the ionic strength of soil solutions on soil properties. It is known that when the ionic strength increases, the double electric layer contracts. The aim of the work is to study the effect of increasing the ionic strength of a soil solution on the rheological properties and soil water retention curve. Loamy soils were studied: sod-podzolic, gray forest, and leached chernozem. The rheological characteristics of the soil pastes were determined on a vibrating viscometer, the soil water retention curve by the method of equilibrium centrifugation. The particle size distribution in the suspensions was determined using a laser diffractometer. In the course of experiments, it was found that an increase in the ionic strength of the dispersion medium in pastes leads to a sharp increase in the viscosity of pastes. From the perspective of double electric layer compression, the viscosity should decrease. In addition, it was found that in soil pastes prepared with 1 N potassium chloride, the amount of rheopexy decreases. At the same time, there is no influence of the ionic strength of solutions on the soil water retention curve, although from the standpoint of double electric layer, it was assumed that the soil water retention curves would shift to the left. The experiments conducted to study the swelling of soil pastes suggest that periodic colloidal structures of a local type exist in soils. Thus, the concept of a double electric layer does not allow us to explain changes in all soil properties.

Salt lick sites, where artificial salt blocks are placed at permanent locations, are common in summer grazing areas for free‐ranging sheep in Norwegian mountains. These areas often overlap with areas used by wild reindeer, and reindeer are frequently observed at these salt lick sites. The first cases of chronic wasting disease (CWD) were discovered among Norwegian wild reindeer in 2016, and salt lick sites were presumed to be hotspots for the transmission of CWD. In this study, we compare soil properties at salt lick and nearby control sites not affected by salt blocks and review how salt‐induced changes may influence the persistence and transmission of CWD. Three wild reindeer areas were studied: one CWD‐affected area, Nordfjella, and two areas without CWD, Knutshø and Forollhogna. The soils at the salt lick sites were strongly influenced by dissolving salt blocks and increased animal activity. The salt lick sites had higher pH and ionic strength and increased levels of sodium (Na), chlorine (Cl), calcium (Ca), magnesium (Mg), zinc (Zn), manganese (Mn), and iodine (I), reflecting the composition of the salt blocks. The increased animal activity was reflected in eroded topsoil causing less soil organic matter (SOM), and there were higher amounts of elements related to defecation and urination, giving higher concentrations of inorganic nitrogen (Inorg‐N), phosphate (PO4‐P), sulfate (SO4‐S), and potassium (K) as well as high gastrointestinal parasite frequency and diversity. The high salt content in the salt lick soils may stimulate geophagy, and as the soil is heavily contaminated by animal excretions, this may facilitate prion transmission. In addition, the high pH and ionic strength in the salt lick soils increase both the cation attraction and anion diffusion toward the soil particles, thereby facilitating both persistence and transmission of CWD. There was an increase in salinity at the salt lick sites in a gradient from west to east, most likely related to the coinciding decrease in precipitation. This suggests that if the use of permanent salt lick sites is discontinued, the salt lick sites in the east will maintain their attraction for congregating animals and geophagy longer than the western sites.

In order to provide important details concerning the adsorption reactions of Sr, batch reactions and a set of both ex situ and in situ Grazing Incidence X-ray Absorption Fine Structure (GIXAFS) adsorption experiments were completed on powdered TiO2 and on rutile(110), both reacted with either SrCl2 or SrCO3 solutions. TiO2 sorption capacity for strontium (Sr) ranges from 550 ppm (SrCl2 solutions, second order kinetics) to 1400 ppm (SrCO3 solutions, first order kinetics), respectively, and is rapid. Sr adsorption decreased as a function of chloride concentration but significantly increased as carbonate concentrations increased. In the presence of carbonate, the ability of TiO2 to remove Sr from the solution increases by a factor of ~4 due to rapid epitaxial surface precipitation of an SrCO3 thin film, which registers itself on the rutile(110) surface as a strontianite-like phase (d-spacing 2.8 Å). Extended X-ray Absorption Fine Structure (EXAFS) results suggest the initial attachment is via tetradental inner-sphere Sr adsorption. Moreover, adsorbates from concentrated SrCl2 solutions contain carbonate and hydroxyl species, which results in both inner- and outer-sphere adsorbates and explains the reduced Sr adsorption in these systems. These results not only provide new insights into Sr kinetics and adsorption on TiO2 but also provide valuable information concerning potential improvements in effluent water treatment models and are pertinent in developing treatment methods for rutile-coated structural materials within nuclear power plants.

The aim of the study was to understand the removal characteristics of engineered nanoparticles (ENP) from sludge treatment processes in wastewater treatment plants (WWTP). Removal of ENP (TiO2, ZnO) was tested on primary and secondary sludge, using differential sedimentation experiments to quantify the attachment of ENP to sludge particulates. To better understand the attachment characteristics, aquatic conditions such as mixed liquid suspended solid concentration, and Ionic strength of the wastewater, were varied to replicate different field conditions of WWTPs. Results showed different degrees of multilayer attachment to sludge surfaces based on the experimental conditions. To verify the effect of ENP surface characters with the sludge attachment, SiO2, ZnO, and TiO2 were tested, showing SiO2 with the highest amount of attachment regardless of its surface charge. With the variation of sludge concentration, up to four degrees of magnitude in sorption was observed. Salt concentrations also showed high impacts on the sorption, where the sorption is decreased by half when doubling the salt concentration. The findings of the current research may aid in understanding the fate of engineered nanoparticles in wastewater treatment plants.

The interaction of the actinides Pu(III), Am(III), Np(V), Np(VI), and U(VI) with hardened cement paste (HCP) prepared from ordinary Portland cement was investigated by batch experiments in a diluted caprock solution (I = 2.5 M) as a function of the solid-to-liquid (S/L) ratio (0.5–20.0 g L−1) and pH (10–13). Independent of the oxidation state of the actinides, strong sorption was observed with Rd values between 104 and 5 × 105 L kg−1. For the hexavalent actinides U(VI) and Np(VI), a decrease in sorption was observed with increasing pH, which could be due to the formation of the AnO2(OH)42− species. CE-ICP-MS measurements of the supernatant solution from the U(VI) batch sorption experiment at pH ≥ 10 indicate that UO2(OH)3− and UO2(OH)42− dominate the speciation. Pu LIII-edge XANES and EXAFS measurements showed oxidation of Pu(III) to Pu(IV) when interacting with HCP. Calcium silicate hydrate (C-S-H) phases effectively immobilize Pu(IV) by incorporating it into the CaO layer. This was observed in a C-S-H sample with C/S = 1.65 and HCP at pH 12.7. Compared to data published in the literature on the retention of actinides on HCP at low ionic strength, the influence of high ionic strength (I = 2.5 M) on the sorption behavior was insignificant.

Fluoroquinolone antibiotics have been extensively used in clinical treatments for human and animal diseases. However, their long-term presence in the environment increases the risk of producing resistance genes and creates a potential threat to ecosystems and the health of humans and animals. Batch equilibrium experiments were utilized to investigate the adsorption and retention behavior and mechanism of the quinolone antibiotic enrofloxacin (ENR) in farmland soil in North China. The adsorption and desorption kinetics of ENR in soil were best fitted by pseudo-second-order model ( R 2  > 0.999). Both the adsorption and desorption processes of ENR in soil reached equilibrium in 1 h. The desorption amounts of ENR were significantly lower than the adsorption amounts, with the hysteresis coefficient ( HI ) being less than 0.7. The adsorption thermodynamic process of ENR followed the Linear and Freundlich models (0.965 <  R 2  < 0.985). Hydrophobic distribution and heterogeneous multimolecular layer adsorption were identified as critical factors in the adsorption process. The adsorption amount of ENR gradually decreased with increasing temperature and the initial concentration of ENR. The adsorption rate of ENR was above 80%, while the desorption rate remained below 15%, indicating strong retention ability. The adsorption rate of ENR in soil decreased with increasing pH, the adsorption rate reached 98.3% at pH 3.0 but only 31.5% at pH 11. The influence of coexisting ions on adsorption primarily depended on their properties, such as ion radius, ionic strength, and hydrolysis properties, and the inhibition of adsorption increased with increasing ionic strength. These findings contribute to understanding the fate and risk of veterinary antibiotics in loess soil in North China.