Thermal stability is one of the most important indexes determining the practical applications of selective catalytic reduction (SCR) catalysts. The influence of typical alkali element on the thermal stability of industrial V₂O₅-WO₃/TiO₂ catalyst is first reported in this work. The activity of the sample is measured, and physicochemical properties are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectrum, field emission scanning electron microscope (FE-SEM), N₂ adsorption-desorption, temperature programmed desorption of NH₃ (NH₃-TPD), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The sintering and anatase-to-rutile phase transformation at high temperature will cause deactivation of SCR catalyst, and low concentration of K can increase the thermal stability. Under the same thermal treatment, the activity (380 °C) of sample deposited by K is more than three times higher than that of the fresh sample without K. Aggregation of vanadia in conventional SCR catalyst favors the sintering and anatase-to-rutile phase transformation of catalysts. Incorporation of K can modify the structure of partial V-OH and form V-OK, which hinders the aggregation of vanadia species and further increases the thermal stability of catalysts.

Panax notoginseng is a well-known phytomedicine used all over the world. In recent years, a certain As contamination of the herb appeared in its planting area due to elevated soil As concentration. We investigated the feasibility of intercropping with Pteris vittata, an As hyperaccumulator, on the reduction of As accumulation in Panax notoginseng and As transfer and transformation in soil-plant system. Results showed that, intercropping could decrease the As concentrations of Panax notoginseng by 9.1–54.3 and 30.9–54.3% and increase the biomasses by 40.7–211.6 and 2.1–153.3 %, respectively, in the H-As (soil As 400.4 mg/kg) and M-As (soil As 85.3 mg/kg) treatments. Compared to the monoculture, the ratio of the nonspecifically adsorbed As in soil was decreased by 17.8 and 34.3 %, and the As transfer factor of Panax notoginseng was increased by 22.2 and 66.3 %, respectively, in H-As and M-As treatments. For As speciation, As(III) and As(V) could be detected at the same time only in root and xylem sap of Panax notoginseng in the H-As treatment, and intercropping could increase the ratios of As(III) by 97.8 and 72.4 %, respectively. In summary, intercropping with Pteris vittata is an applicable approach to reduce the As accumulation in Panax notoginseng.

In this work, metal sorption onto grape stalks waste structural compounds and extractives has been studied for determining their role in Cr(VI), Cu(II) and Ni(II) metal sorption. For this purpose, a sequential extraction of extractives and other compounds from the lignocellulosic material has been carried out. The resulting solid samples obtained in the different extraction processes were used as sorbents of Cr(VI), Cu(II) and Ni(II). Sorption results were discussed taking into account the elemental composition and polarity of the solid extracts. Results indicated that tannins and polyphenols are involved in chromium reduction and sorption. Lignin and celluloses are involved in chromium, Cu(II) and Ni(II) sorption. FTIR analysis confirmed the involvement of lignin moieties in the studied metal ions sorption by grape stalks waste. This study presents a new approach on metal sorption field as the knowledge of the role of the sorbent chemical compounds is essential to determine the key sorbent compounds in the sorption process.

The Rio Santiago in the Cordillera Negra of Peru is severely contaminated by acid mine drainage in its headwaters. In a strongly acid stream, at about 3800 m above sea level (masl), microterraces were found with terrace walls built up of dead moss, with encrustations and interstitial fine, creamy sediment. The stream water was turbid due to the presence of similar suspended sediment, which also occurred as a thin basal layer in inter-rim basins. The moss was identified as the rare bryophyte Anomobryum prostratum (Müll. Hal.) Besch. Chemical and mineralogical analyses show that green, living parts of the moss are gradually coated by Al/Fe (hydr)oxides, inducing their senescence and death. The necromass is covered by creamy crusts through precipitation of schwertmannite-type material from the stream water and simultaneous ‘capture’ of fine sediment. The latter consists of a mixture of precipitate and fine detrital primary minerals. These processes are held responsible for the formation of the microterraces, which regarding their composition and environment seem to be unique. Remarkable is the high As content of the creamy crusts and sediment, attributed to strong sorption of As, whereas its solute concentration is relatively low. This calls for more attention to suspended fine sediment in the assessment of environmental risks of stream water use. Lastly, the results raise serious doubts about the use of aquatic bryophytes as bioindicator for chemical pollution in acid mine drainage-polluted streams.

This study investigates the removal of Cu(II) from aqueous solutions by biosorption-flotation as a function of several parameters, such as collector type, pH, molar ratio, air pressure, time, and initial metal concentration. Dissolved air flotation was applied as a polishing technique for the additional purification of the effluent resulted after biosorption. The obtained results were supported by the physicochemical characteristics of the surfactants used as flotation reagents and suggested that cetylpyridinium bromide (CPB) was the optimum collector for Cu(II) ion removal. Cu(II) removal efficiency exhibited a maximum of 97.09 % in the following operating conditions: biosorption pH 4.5, Cu(II) initial concentration 250 mg/L, biosorbent dosage 0.5 % w/v, agitation rate 200 rpm, temperature 20 °C, biosorption time 30 min, flotation pH 9, air pressure 4.5 × 10⁵ Pa, dilution ratio 3:1, flotation time 10 min, collector CPB 0.01 M, and molar ratio collector/Cu(II) 5 × 10⁻¹:1. The experimental data confirmed that the flotation stage contributed to the optimization of the overall separation process.

Conversion of native forest to pastures is a common practice worldwide; it has complex effects on river biota that are related to activity type and intensity. This work was conducted in order to evaluate the effects of cattle grazing on environmental features and to select the most appropriate measures based on the macroinvertebrate community as indicators of ecological changes. Physicochemical features, riparian ecosystem quality, habitat condition, and benthic macroinvertebrates were investigated in streams draining pastures and were compared to reference streams located in nonimpacted native forested catchments. Strong evidence of sediment deposition was observed at pasture streams, which had higher percentage of sand in the streambed but also increased levels of suspended solids. Pasture sites had significantly higher water temperature and conductivity as well as lower dissolved oxygen concentrations than did forested sites. Both riparian quality and in-stream habitat condition were degraded at pasture sites. Among metrics, total richness, Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness, Plecoptera richness, Shannon diversity, percentage of dominant taxon, percentage of Chironomidae species, shredder richness, and percentage of predator resulted to be the most consistent measures by displaying stronger responses to impairment. Our results suggest that forest conversion to pasture for livestock practices is diminishing macroinvertebrate biodiversity and potentially changing functioning and dynamics of Patagonian mountain streams as well. Damage prevention on riverine landscapes by restoring riparian ecosystems, replanting missing vegetation in buffer areas, and limiting livestock access to the riverbanks could contribute to enhance the ecological integrity at converted areas. A more extended and comprehensive use of macroinvertebrate metrics could contribute to better understand and evaluate impact effects of these extended land use activities and to promote conservation strategies.

The model of contaminant transport between the abiotic components of the lake water-sediment system is presented. The implementation of the model, which uses radioactive material as a contaminant, and the evaluation of parameter values are discussed in the work. A semi-analytical solution of the simulation of the dynamics of contaminant transport in the lake water and one-dimensional sediment solute transport including non-equilibrium processes is presented. The model includes a concept of dynamics of the contaminant sorption in lake water and sediment compartments, considering the specific porous structure of sediments, the contaminant material exchange between the liquid and solid phases of sediments. The key processes included in the model are sedimentation, resuspension, diffusive exchange of solute at the lake water-sediment interface and advection-diffusion in sediment solute. Modelling of the contaminant transport in both spheres (lake water and bottom sediments) is influenced by non-equilibrium and transformation reactions. Special attention was paid to the contamination balance between the two spheres in the interface area. The ranges of boundary and initial conditions were extended, and final results were obtained using an accurate and robust numerical inversion calculation based on the De Hoog algorithm. Therefore, the model can be used in experimental measurements interpreting the contaminant profile in lake sediments as well as a part associated with the comprehensive determination of the volumetric activity, in the estimation of irradiation doses due to radionuclides released into the lake water.

The drinking water treatment plant (WTP) of the city of Turin (NW Italy), with a treatment capacity of 40 × 10⁶ m³/year, has a basin that is employed as a lagooning pretreatment facility. This study aims to assess the effect of the basin on several environmental parameters (temperature, dissolved oxygen (DO), turbidity, pH, chloride, nitrite, and total chlorophyll) of the river water before entering the WTP and monitor the changes inside the basin caused by the seasonal hydrological and biological cycles. Sampling was carried out on 16 dates over 3 years at the inlet and outlet channel of the basin and in five locations along three depth values (1, 6, and 12 m, i.e., at the bottom). The results of the 3-year monitoring campaign demonstrated that the basin had an effect on pH (p = 6.6 × 10⁻⁹), DO (p = 0.000072), turbidity (p = 0.011), and chlorophyll (p = 0.033). No significant changes regarding nitrite (p = 0.11), chloride (p = 0.94), and temperature (p = 0.66) were detected. The results gathered from the sampling campaign inside the basin demonstrated that, during the year, the basin experienced the following: two states of complete mixing in early spring and fall, when the differences in temperature between the surface and the bottom of the basin were less than 1 °C; a condition of late spring/summer stratification with a temperature difference between the surface and the bottom of 4–5 °C and a difference in DO, pH, and total chlorophyll concentration that increased throughout the spring season; and one or more states of summer circulation due to the weak stability of the warm season stratification. During the states of circulation, the persistent algae photosynthetic activity tended to cause a quick change in the concentration of DO, total chlorophyll, and pH value in the most superficial layer of the basin. The results of the principal component analysis (PCA) showed a strong direct relationship between the weight of the first component and the hydrodynamic states of the basin (stratification/circulation) and an inverse relationship between the weight of the second component and the intensity of photosynthetic activity of algae species.

Sculpins are widely used as key species for monitoring heavy metal pollution near arctic mine sites. Typically, metal concentrations in liver and muscle tissue have been used as a proxy for metal exposure but such analyses lack temporal information of uptake and accumulation. Otoliths (ear bones) are considered metabolically stable and can potentially contain a complete record of the fish’s metal exposure history. To investigate the otolith chemistry of sculpins and the potential of these as records of metal exposure, common sculpins (Myoxocephalus scorpius) were collected at five sites near a former Pb–Zn mine in West Greenland. Otoliths were analyzed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 12 elements of which Mg, Mn, Sr, Ba, and Pb were detected. The highest Pb concentrations were found within the otoliths from the most Pb-polluted sites near the mine (up to 0.6 ppm), and decreasing concentrations were observed in a gradient away from the mine. Notably, Pb and Sr variations were closely correlated and showed an annual oscillatory pattern with peaks consistently found in the winter zones. It is not clear to what the extent high winter-time accumulation of Pb in the otoliths is due to high winter-time exposure of Pb through diet or water and/or to physiological processes such as growth in the sculpins. The study indicates that LA-ICP-MS analyses of sculpin otoliths have the potential to become a valuable method for assessing time-resolved metal loading near mine sites but also that more studies are required to investigate the links between metal sources, pathways, and processes affecting otolith metal deposition.

The reversible and resistant components of adsorption and desorption of munition constituents (MCs) on soils was studied to determine the environmental fate of these contaminants. The long-term desorption of MCs has applicability in formulating accurate risk assessments for operational military ranges. Batch experiments near 1:1 (w/v) soil-to-solution ratios reflecting field conditions using solutions containing mixtures of HMX, RDX, and nitroglycerine (NG) were conducted. The three soils used varied from 0.04 to 13.3 % organic matter. The experiment involved one adsorption step followed by four consecutive desorption steps. Adsorption times were 2, 5, 10, and 30 days. For each adsorption time, desorption times were carried out for 1, 12, 24 and 72 h and 30 days. The reversible/resistant component model was applied to the data. The model predicted the desorption concentrations of the MCs in the soil with root mean square errors of approximately 0.05 to 0.2 μg g soil⁻¹. The extent of desorption hysteresis is not changed by the length of desorption time, irrespective of the initial adsorption time.