In this paper, the application of biofiltration is investigated for controlled removal of gas phase chloroform through cometabolic degradation with ethanol. A trickle bed air biofilter (TBAB) operated under acidic pH 4 is subjected to aerobic biodegradation of chloroform and ethanol. The TBAB is composed of pelleted diatomaceous earth filter media inoculated with filamentous fungi species, which served as the principle biodegrading microorganism. The removal efficiencies of 5 ppmᵥ of chloroform mixed with different ratios of ethanol as cometabolite (25, 50, 100, 150, and 200 ppmᵥ) ranged between 69.9 and 80.9%. The removal efficiency, reaction rate kinetics, and the elimination capacity increased proportionately with an increase in the cometabolite concentration. The carbon recovery from the TBAB amounted to 69.6% of the total carbon input. It is postulated that the remaining carbon contributed to excess biomass yield within the system. Biomass control strategies such as starvation and stagnation were employed at different phases of the experiment. The chloroform removal kinetics provided a maximum reaction rate constant of 0.0018 s⁻¹. The highest ratio of chemical oxygen demand (COD)ᵣₑₘₒᵥₐₗ/nitrogenᵤₜᵢₗᵢzₐₜᵢₒₙ was observed at 14.5. This study provides significant evidence that the biodegradation of a highly chlorinated methane can be favored by cometabolism in a fungi-based TBAB.

Chlorine added to drinking water as a disinfectant is a concern of this generation. This is because chlorine reacts with dissolved organic compounds to form polychlorinated complexes that are carcinogenic. Available methods for the removal of chlorine and chlorinated compounds include adsorption, precipitation, electrolysis and ozonation, but some result in the generation of more toxic compounds. This study explored the use of zero-valent bimetals Fe/Zn for the degradation of chlorinated compounds in water which did not generate toxic by-products. The zero-valent bimetallic material was anchored on a polystyrene waste material as a green method of cleaning the environment. It was prepared through nitration, amination, complexation and reduction. The resulting solid material was characterised using Fourier transform infrared (FTIR). The material was also characterised using XPS which confirmed the presence of metals anchored on the material through complexation. The metals were also found to be present upon reduction to zero valence and even after the degradation process of the chlorinated organic compounds. It was then applied for the removal process. Optimization parameters such initial halide concentration, effect of time and bimetal dosage variation were established using synthetic water samples. It was found that the substrate-anchored ZVB material had a degradation capacity of 4.532, 5.362 and 4.513 μmol l⁻¹ for 1,2-dichloroethane, 2-chloro-2-methylpropane and 1-chlorobutane, respectively. The material was then applied on real samples sourced from Nairobi. Quantification of chlorine was done using potentiometric methods and the results confirmed that the degradation was first order. The degradation capacities were found to be 2.37 ± 0.01, 3.55 ± 0.01 and 3.72 ± 0.01 in that order.

This study aims to produce and apply a biosurfactant from Gordonia westfalica GY40 for enhancing fuel oil solubilization and degradation in seawater. The immobilization of G. westfalica GY40 cells on chitosan flakes increased biosurfactant yield, and we achieved a biosurfactant concentration as high as 1.85 g L⁻¹ when using 2 % soybean oil as the carbon source. The critical micelle dilution (CMD) value of cell-free broth was 25 % and the lowest surface tension was 35 mN m⁻¹. The cell-free broth was able to solubilize and disperse fuel oil, at efficiencies corresponding to biosurfactant concentrations and CMD values. The surface activity of cell-free broth was stable under wide ranges of salinity, temperature, and pH. For the oil degradation test, cell-free broth at 0.5× CMD was added along with polyurethane foam-immobilized Gordonia sp. JC11, an efficient oil-degrading bacterial inoculum, to fuel oil spiked seawater. The system removed 81 % of 1 g L⁻¹ fuel oil in nutrient seawater medium within 6 days. When tested with three seawater samples collected along the Thai coastal area, the addition of both biosurfactant and immobilized Gordonia sp. JC11 was able to remove 60–70 % of 1 g L⁻¹ fuel oil, while the natural attenuation (control) removed only 26–35 % of fuel oil. The application of cell-free broth reduced the extraction and purification steps. In addition, the simple production of G. westfalica GY40 biosurfactant and Gordonia sp. JC11 inoculum suggested that they are suitable for cleaning-up oil spills in seawater.

Wintertime precipitation sample data from 55 Snowpack sites and 17 National Atmospheric Deposition Program (NADP)/National Trends Network Wetfall sites in the Rocky Mountain region were examined to identify long-term trends in chemical concentration, deposition, and precipitation using Regional and Seasonal Kendall tests. The Natural Resources Conservation Service snow-telemetry (SNOTEL) network provided snow-water-equivalent data from 33 sites located near Snowpack- and NADP Wetfall-sampling sites for further comparisons. Concentration and deposition of ammonium, calcium, nitrate, and sulfate were tested for trends for the period 1993–2012. Precipitation trends were compared between the three monitoring networks for the winter seasons and downward trends were observed for both Snowpack and SNOTEL networks, but not for the NADP Wetfall network. The dry-deposition fraction of total atmospheric deposition, relative to wet deposition, was shown to be considerable in the region. Potential sources of regional airborne pollutant emissions were identified from the U.S. Environmental Protection Agency 2011 National Emissions Inventory, and from long-term emissions data for the period 1996–2013. Changes in the emissions of ammonia, nitrogen oxides, and sulfur dioxide were reflected in significant trends in snowpack and wetfall chemistry. In general, ammonia emissions in the western USA showed a gradual increase over the past decade, while ammonium concentrations and deposition in snowpacks and wetfall showed upward trends. Emissions of nitrogen oxides and sulfur dioxide declined while regional trends in snowpack and wetfall concentrations and deposition of nitrate and sulfate were downward.

Municipal landfill soils are not able to retain heavy metals indefinitely, and these metals can migrate into the groundwater. Environmental contamination induced by toxic metals creates a societal health risk. The objective of this work is to study the ability of landfill soil to retain metals (Pb, Cd, Cu, Fe and Zn). The soil came from the municipal solid waste dump of the City of Yamoussoukro (Côte d’Ivoire). Operating parameters such as thickness of soil, metal concentration and filtered volume were investigated. A factorial experimental design was used to determine which parameters influence the metal retention rate. Thickness of soil and metal concentration were the most important factors influencing metal retention. Using a 2³ factorial matrix, the best performances for metal retention (99.8–100 % removal) were obtained by selecting a thickness of soil of 2.0 cm, an initial metal concentration of 50 mg L⁻¹ and 200 mL of metallic solution. The optimal experimental conditions for metal retention were then investigated using the Excel Solver program. Between 98.9 and 99.9 % of the metals were retained in subsequent experiments using these optimal conditions (soil thickness ranging between 10 and 14 cm and metal concentration of up to 300 mg L⁻¹ in 400 mL of metallic solution).

Fibrous mats of polymer/clay were obtained by electrospinning method, and their capacity for heavy metals removal from water was evaluated. Four different fibrous mats were prepared from a corresponding polymer/clay solutions. The precursor materials employed were poly-ε-caprolactone, polyvinyl alcohol polymers, kaolin, and metakaolin clays. Raw materials and the prepared fiber mats characterization were carried out using scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, termogravimetric analysis, differential thermal analysis, and differential scanning calorimetry. Elemental composition of the materials was obtained using energy-dispersive X-ray spectroscopy. The environmental applications of polymer/clay materials were tested for water treatment by heavy metals (cadmium (Cd⁺²), chromium (Cr⁺³), copper (Cu⁺²), and lead (Pb⁺²)) sorption. Kinetic adsorption studies were conducted employing heavy metal solutions with initial concentration of 200 mg/L, and the amount of heavy metal adsorbed and kinetics parameters was determined using inductively coupled plasma-optical emission spectroscopy (ICP-OES). According to the kinetic data, the adsorption process of Cd⁺², Cr⁺³, Cu⁺², and Pb⁺² onto polymer/clay is favorable for the prepared materials and they follow a pseudo-first-order model according to the kinetic analysis. Additionally, the intraparticle diffusion was evaluated by applying the Morris and Weber model; in order to investigate the contribution of film resistance to the kinetics of the heavy metals adsorption, the adsorption kinetic data was further analyzed by Boyd’s film-diffusion model.

Untreated arsenic polluted groundwater is threatening people health, especially the people in rural areas. Soil may become one kind of promising natural material applied conveniently in rural areas for the treatment of arsenic polluted groundwater, due to its abundance, low cost, and high adsorption efficiency. The present study investigated arsenic(V) (As(V)) adsorption on two red soil samples weathered from granite (RSG) and sandstone (RSS). The two soil samples contain similar mineral types but show relatively high differences of content of iron, aluminum, and organic matter (OM), as well as point of zero charge (pHPZC) and specific surface area (SSA). Batch experiments were performed to examine the effect of initial As(V) concentration, solution pH, and temperature on the kinetics of the adsorption of As(V) by the two soil samples. The experimental results showed that the As(V) adsorption onto the two soil samples was influenced by the physicochemical properties of the soils, especially the content of iron and aluminum, the OM, as well as the pHPZC, and chemisorption was the main adsorption mechanism. The RSG sample with higher content of iron and aluminum and pHPZC showed relatively high adsorption efficiency. The OM played a negative role in the adsorption process, especially as the As/Fe molar ratio is higher. Higher adsorption capacities for the two soil samples were both obtained at lower initial As(V) concentration (1.50 and 4.0 mg/l), lower pH value (5.0), and higher temperature (313 K). Comparing to the RSS, the RSG is more suitable for the treatment of As(V)-polluted groundwater. Considering the experimental results and the natural conditions, the suggested operational conditions are pH around 7.0, temperature 293–303 K, As(V) concentration less than 4.0 mg/l, and hydraulic retention time no less than 180 min.

We studied the recovery of brown trout populations from 1970 to 2010 in acidified mountain lakes with low ionic content in southwestern Norway. A total of 181 test fishing surveys with gill net series were performed in 59 lakes. We found that the most significant recovery occurred during the 1980s and early 1990s. In this period, only limited improvement in the water chemistry related to acidification, i.e., pH, was observed. However, due to a temporary increase in sea salt deposition, water conductivity almost doubled during this period. In many of the mountain lakes in the study area, the brown trout populations are restricted by ion deficit. Moreover, greater ionic strength ameliorates the effects of acidification by increasing the tolerance to H⁺. Well-established relationships between conductivity and the relative abundance of brown trout (CPUE) explain the observed recovery. We conclude that the dynamics of the sea salt ion contribution should be taken into consideration wherever biological recovery in very diluted water qualities is being evaluated.

A dramatic increase in winter (December–February) temperature by 7.2 K (1.1 K per decade) since 1950 has occurred in the Ulan Bator basin, Mongolia. This increase in temperature strongly exceeds the global average of late twentieth century warming and even exceeds warming in most of the polar regions with pronounced increases in temperature. The exceptional warming is restricted to Ulan Bator within the Mongolian forest-steppe region and to wintertime. This suggests that the observed warming could result from radiative forcing by black carbon aerosols. In winter, Ulan Bator’s air is heavily polluted by particulate matter, including black carbon, originating from the combustion of low-quality fuel at low temperature. Winter smog has strongly increased in recent decades, concomitant to the increase in winter temperature, as the result of a strong increase in the city’s population. Exponential growth of Ulan Bator’s population started in the mid-twentieth century, but since 1990, altered socioeconomic frame conditions and a warming climate have driven more than 700,000 pastoralists from rural Mongolia to Ulan Bator where people live in provisional dwellings and cause Ulan Bator’s heavy air pollution. Tree-ring analysis from larch trees growing at the edge of the Ulan Bator basin shows negative correlation of stem increment with December temperature. This result suggests that milder winters promote herbivores and, thus, reduce the tree’s productivity. The negative impact of winter warming on the larch forests adds to adverse effects of summer drought and the impact of high sulfur dioxide emissions. Winter warming putatively associated with high atmospheric concentrations of black carbon aerosols in the Ulan Bator basin is an interesting example of a case where greenhouse gas-mediated climate warming in an area where people themselves hardly contribute to global greenhouse gas emissions affects both humans and ecosystems and causes additional local climate warming.

Psychiatric pharmaceuticals, such as anxiolytics, sedatives, hypnotics and antidepressors, are among the most prescribed active substances in the world. The occurrence of these compounds in the environment, as well as the adverse effects they can have on non-target organisms, justifies the growing concern about these emerging environmental pollutants. This study aims to analyse the effects of six psychotropic drugs, valproate, cyamemazine, citalopram, sertraline, fluoxetine and oxazepam, on the survival and locomotion of Japanese medaka Oryzias latipes larvae. Newly hatched Japanese medaka were exposed to individual compounds for 72 h, at concentrations ranging from 10 μg L⁻¹ to 10 mg L⁻¹. Lethal concentrations 50 % (LC₅₀) were estimated at 840, 841 and 9,136 μg L⁻¹ for fluoxetine, sertraline and citalopram, respectively, while other compounds did not induce any significant increase in mortality. Analysis of the swimming behaviour of larvae, including total distance moved, mobility and location, provided an estimated lowest observed effect concentration (LOEC) of 10 μg L⁻¹ for citalopram and oxazepam, 12.2 μg L⁻¹ for cyamemazine, 100 μg L⁻¹ for fluoxetine, 1,000 μg L⁻¹ for sertraline and >10,000 μg L⁻¹ for valproate. Realistic environmental mixture of the six psychotropic compounds induced disruption of larval locomotor behaviour at concentrations about 10- to 100-fold greater than environmental concentrations.