Silicate clay materials are promising natural adsorbents with abundant, low cost, stable, and eco-friendly advantages, but the limited adsorption capacity restricts their applications in many fields. Herein, palygorskite (PAL) was facilely activated with alkali to enhance its adsorptive removal capability for methylene blue (MB). The effects of alkali activation on the microstructure, physicochemical, and adsorption properties of PAL for MB were intensively investigated. It was found that the moderate alkali activation can partially remove the metal cations (i.e., Al³⁺, Mg²⁺) and Si in the crystal backbone of PAL by which new “adsorption sites” were created and the surface negative charges increased. The adsorption capacity and rate of PAL for MB were evidently enhanced due to the effective activation. The adsorption isotherms were described by Freundlich isotherm model very well, and the adsorption kinetics can be accurately presented by a pseudo-second-order model. It can be inferred from the fitting results that the overall adsorption process was controlled by external mass transfer and intra-particle diffusion (the dominant role). The multiple adsorption interactions (hydrogen bonding, electrostatic interactions, mesopore filling, and complexing) were turned out to be the dominant factors to improve the adsorption properties. It was revealed that the activated PAL could be used as a potential adsorption candidate for environmental applications.

Sixty years of air pollution from two Cu-Ni smelting plants (“Pechenganikel” and “Severonikel”) in the Kola region in northwest Russia have posed a severe threat for water quality, specifically acidification, in subarctic lakes. In the last two decades, emissions of SO2, Cu and Ni from the smelters have declined with 33 %, 40 % and 36 %, respectively. The 75 lakes in Kola Peninsula were sampled with 5-year intervals for the period 1990 to 2010. In addition, were analysed for major anions and cations, DOC and heavy metals. The lakes were grouped according to geology and distance to emission sources into 6 subregions. The most acid-sensitive lakes are located on granites, quartz sands or in highlands. Since 1990, ANС has increased, which is connected to the reduction of the contents strong acids in water (sulphate, chloride) while base cations concentrations have been almost unchanged. Despite the reduction of sulphate, concentrations of alkalinity have not increased in lake water. We have found an increase in concentration of dissolved organic carbon (DOC) and nutrients in Kola lake waters over a 20-year period. We suggest this phenomenon can be explained by two mechanisms: a reduction in deposition of strong acids and warming climate. Concentrations of Ni and Cu have decreased 5-10-fold over the last 20 years. We conclude that reduced emissions from Cu-Ni smelting plants has led to improved water quality in the Kola region.

Fluoroquinolone antibacterial agents (FQs) are the most commonly detected antibiotics in soil/groundwater which cause chronic effects on human beings as well as aquatic ecosystems. The current situation of the regulation, occurrence, fate, and sources of FQs in soil/groundwater was systematically analyzed in this paper. And then, the important factors affecting milligram per liter concentration of FQs sorption in soil, such as pH, cation exchange, clay minerals, organic content, surface complexation, and microbial degradation or transformation, were summarized. Actually, nanogram-microgram per liter concentration is detected frequently in soil/groundwater by far. Due to the extensive application of FQs and its relatively stable physicochemical characteristics, the higher concentration in soil/groundwater would appear in the coming decades which may exert a threat to freshwater and human beings. To the knowledge of the authors, no full-scale fate, occurrence, spatial, and temporal variations of FQs in soil/groundwater have been reported in the scientific literature. Therefore, it is recommended that more comprehensive studies are required to fill knowledge gaps in low-concentration transport, fate and occurrence, spatial, and temporal variations of FQs in soil/groundwater and their potential risk assessment to human and ecosystem.

The effects of ultrasonic wave irradiation on bacterial inactivation were investigated as functions of the ionic strength (IS), humic acid, and temperature. Escherichia coli (E. coli) D21g was selected as a model bacterium to better catch the effect of three parameters on the cell inactivation behavior. The Suwannee River humic acid (SRHA) was chosen as a representative humic acid, and the concentration for ultrasonic tests was kept to 10 ppm. The frequency of ultrasonic wave employed was 20 kHz, and the inactivation efficiency at two exposure times (5 and 10 min) was compared. The removal efficiency of E. coli D21g was confirmed to be 100 % at 10 min in all conditions except the 10-min temperature-controlled condition. The removal efficiency with the high IS was greater than that with the low IS, by 26 %, confirming an increase in the bacterial inactivation level with increasing IS. The bacterial removal efficiency with SRHA (96.6 %) was much greater than that without SRHA (69.6 %). The removal efficiency in the temperature-controlled condition (at a relatively low temperature) was significantly lower than that in the uncontrolled condition. Furthermore, the trend obtained using two other types of bacteria with more complex surface structure was consistent with that using the E. coli D21g cells.

Lignin is the major polluting and colouring constituent present in pulp and paper mill effluent. To degrade lignin and its derivatives, bacterial enzymes can play an important role due to stability at extreme environmental conditions. This study explored the degradation of pulp and paper mill effluent by a rod-shaped Gram-positive bacterial strain RJH-1, isolated from sludge, based on its efficiency to reduce COD, colour, AOX and lignin content. This bacterial isolate was able to grow in nitrogen-free Jensen medium. Further, RJH-1 was identified as Brevibacillus agri strain after 16 s rRNA gene sequencing. Degradation potential of this isolated bacterial strain was evaluated by batch and semi-continuous reactor study. In batch study, the isolate reduced 69 % COD, 47 % colour, 37 % lignin and 39 % AOX after 5 days whereas in control flask, 40 % COD, 26 % colour, 19 % lignin and 22 % AOX reduction was observed by the indigenous bacteria present in wastewater. During semi-continuous reactor study, it reduced 62 % COD, 37 % colour, 30 % lignin and 40 % AOX of effluent at a retention time of only 32 h whereas the reduction in control reactor was 36 % COD, 21 % colour, 18 % lignin and 29 % AOX. This study confirmed that the B. agri has the potential to degrade the lignin and reduce the colour and COD of the pulp and paper mill waste water.

Ground-level ozone (O₃) pollution has affected carbon metabolism in tree species, which becomes one of the top environmental issues in China. In this paper, 1-year-old seedlings of Phoebe bournei and Pinus massoniana Lamb. were grown under field conditions at a rural site near the city of Taihe (Jiangxi Province). The plants were exposed in open-top chambers either to charcoal-filtered air or nonfiltered ambient air for 145 days. At the end of the growth season, the plants were harvested and the major nonstructural carbohydrates in leaves and roots were determined. Exposure to nonfiltered ambient air compared with filtered air controls caused an increase of sucrose, glucose, fructose, starch, and total nonstructural carbohydrates (TNCs) in fine roots of Ph. bournei, while there is no change in carbohydrate contents in Pi. massoniana roots. Compared with filtered air, in Ph. Bournei, starch and TNCs in leaves were reduced by 48 and 7 %, respectively, in ambient O₃. While, ambient O₃ just increased TNC content by 8.9 % in Pi. massoniana needles compared to filtered air. In summary, ambient O₃ affected carbohydrate metabolism of these two subtropical tree species in China, and Pi. massoniana was less sensitive than Ph. bournei. O₃ induced much greater changes in the amounts of carbohydrates in roots than in leaves.

Winnipeg is a city in the Canadian Prairies with a population of about 600,000. Like many other cities and towns in this region of Canada, the city is surrounded by agriculture. Weekly bulk deposition samples were collected from May to September in 2010 and 2011 and analyzed for 43 pesticides used in Prairie agriculture. Fourteen herbicides, five herbicide metabolites, two insecticides, and two fungicides were detected with 98.5 % of the samples containing chemical mixtures. Glyphosate is the most widely used pesticide in Prairie agriculture and accounted for 65 % of the total pesticide deposition over the 2 years. Seasonal glyphosate deposition was more than five times larger in 2011 (182 mm rain) than 2010 (487 mm rain), suggesting increased glyphosate particulate transport in the atmosphere during the drier year. The seasonal deposition of ten other frequently herbicides was significantly positively correlated with the amount of herbicides applied both in and around Winnipeg (r = 0.90, P < 0.001) and with agricultural herbicide use around Winnipeg (r = 0.63, P = 0.05), but not with agricultural herbicide use province wide (P = 0.23). Herbicides 2,4-D (2,4-dichlorophenoxyacetic acid), dicamba, and mecoprop had known urban applications and were more consistently detected in samples relative to bromoxynil and 2-methyl-4-chlorophenoxyacetic acid (MCPA) whose frequency of detections decreased throughout August and September. The Canadian Water Quality Guidelines for irrigation water were frequently exceeded for both dicamba (75 %) and MCPA (49 %) concentrations in rain. None of glyphosate concentrations in rain exceeded any of the Canadian Water Quality Guidelines established for this herbicide.

The impacts of phenanthrene and its nitrogen-containing analogues (N-PAHs) on seedling emergence and plant biomass of two terrestrial plant species, Lactuca sativa (lettuce) and Lolium perenne (rye grass), were investigated in soil over a 21-day exposure period. The data over 0–90-day soil-chemical contact time revealed that seedling emergence and plant biomass were significantly affected by N-PAHs even at the lowest concentration of 10 mg/kg. N-PAH amended soils showed greater inhibitory effects on seedling emergence and early plant biomass than phenanthrene amendments with incubations overtime. The degree of inhibition (% inhibition) on seedling emergence over time was 33.3 % (lettuce) and 46.7 % (rye grass) for the phenanthrene, and 53.3 % (lettuce) and 93.3 % (rye grass) for the N-PAHs, respectively, suggesting greater sensitivity of seedling emergence and early plant biomass on N-PAH-contaminated soil. The results from this study will contribute to data gaps for poorly managed chemicals/chemical groups for environmental risk assessment and might be useful in the development of new approaches for hazard assessment of contaminated systems.

Salinization is a global problem, including in California, USA, where over two million hectares of irrigated lands have deteriorated due to salt loading. Because of freshwater shortage, some farmlands are also irrigated with agricultural drainage water, which further exacerbates the salinization process. With the objectives of rapidly quantifying spatial and temporal progression of salinization and identifying yield potential for a high-value crop, we conducted 2-year salinity surveys in a salt-affected farm in California by utilizing a dual dipole electromagnetic induction technology (EM38). The EM-predicted conductivity (ECₑ) was consistent with the ground-truth soil data ECₛ and increased with depth. About 50 and 25 % of the ECₑ data in moderately (A) and severely (B) affected salinity zones surpassed 500 and 1000 mS m⁻¹ levels, respectively. In the northern part of B, up to 70 % samples remained within 500–1000 mS m⁻¹ range. There was eastbound salt loading in the northern and southern parts of A. Rhizosphere salinity showed spatial dependence up to 500 m lateral distance. The shifts in salinity could be due to dispersion and leaching of solutes. High crop yield reduction was estimated in the southwestern and northeastern parts of the field that had typically elevated ECₑ. Around 43 % surveyed area was conducive to attaining 80 % of full yield potential, and the central part of the field was determined to be most suitable for crop growth. Coupling of EM results with production values indicated that under elevated saline condition, it would be feasible to grow a high-value tomato crop.

Measurement of the concentration of dissolved carbon dioxide in ground and surface aqueous environments is needed for a wide variety of scientific and industrial applications. These environments can be fresh, saline, or transitional in nature and can be hydrochemically complex. A next generation of sensors, like fiber-optic sensors, offer real-time, direct, distributed sensing of dissolved carbon dioxide and are an improvement over current technology for many applications; however, these sensors may be susceptible to signal disturbance when deployed in hydrochemically complex, natural environments. This complexity can best be characterized using hydrochemical modeling techniques. The modeling software, phreeqc 2.18, was used to conduct a comprehensive review to gain perspective on published data of natural water samples. Freshwater, saltwater, and transitional environments were characterized in terms of the distribution of carbonate and non-carbonate species present. Saline, transitional, and deep freshwater environments had the broadest range of carbonate distribution and species that may cross-interfere with sensor response. These data should be used to build complex laboratory test solutions that mimic the natural environment for use in sensor development. In some cases, specially engineered membranes may be required to mitigate the potentially cross-interfering effect of these ions.