The aim of this study was to characterize qualitatively and quantitatively the composition of the main rhizodeposits emitted from maize (Zea mays) under Cd stress, in order to discuss their role in Cd availability and tolerance. Maize was grown for 6 weeks in sand at four Cd exposure levels (0, 10, 20, and 40 μM Cd in nutrient solution) and two types of rhizodeposits were collected at the end of cultivation period. Mucilage and other molecules adhering to rhizospheric sand were extracted with a buffer before root exudates were collected by diffusion into water. Total carbon, proteins, amino acids, and sugars were analyzed for both rhizodeposit types and about 40 molecules were identified using GC-MS and LC-MS. Cadmium effect on plant morphology and functioning was slight, but consistent with previous works on Cd toxicity. However, rhizodeposition did tend to be impacted, with a decrease in total carbon, sugars, and amino acids correlating with an increasing Cd content. Such a decrease was not noticeable for proteins in root exudates. These observations were confirmed by the same trends in individual compound contents, although the results were generally not statistically significant. Many of the molecules determined are well-known to modify, whether directly or indirectly, Cd speciation and dynamics in the soil and could play a role in Cd tolerance.

In this study, we attempt to prospect potential bacterial isolates from mangrove sediments of Mangalavanam, Kerala, India, with positive carbonic anhydrase (CA) activity to sequester carbon dioxide by calcium precipitation process. Fifteen bacterial colonies (M1–M15) isolated were screened for their carbonic anhydrase enzyme production potential based on p-nitro phenol acetate assay. Based on the secondary screening, M3 and M8 were identified as the most potential for carbonic anhydrase production. The specific activity of the partially purified CA enzyme from M3 and M8 were 44 U mg⁻¹ and 76 U mg⁻¹ respectively. The enzyme activity increased by 1.6-fold upon precipitation by acetone (80%). The potential isolate which higher CA production, M8 was identified as Bacillus altitudinis based on 16S rDNA sequencing. Soil microcosm was established to study carbonic anhydrase production and CO₂ sequestration ability of B. altitudinis M8 strain. B. altitudinis M8 strain could reduce CO₂ by 75 ± 0.12% in microcosm composed of sterilized soil with bacteria (SSB) and by 97 ± 0.34% in microcosm with sterile soil with enzyme (SSE). Hence, the application of enzyme was found to be more effective in removing CO₂ when compared to bacterial inoculum. To further understand the bio-mineralization ability of this microbial isolate, calcium precipitation assay was conducted. There was a reduction of 42.22 ± 0.23% of free calcium in the medium through calcite precipitation. The carbonic anhydrase-mediated calcium precipitation by B. altitudinis M8 strain could be effectively employed in the process of carbon dioxide sequestration.

Increasing applications of rare earth elements (REEs) and improving technologies have led to increased demand. Because of their limited availability and depletion of most resources, the recovery of these elements from waste has become important. The use of cost-effective materials for this purpose and the high value that can potentially be recovered would be beneficial and attractive to many industries using REEs. In this study, natural zeolite and bentonite were used in batch studies to recover REEs (La, Y, Lu, Sm, Pr, Tm, Ce, Nd, Yb, Gd, Eu, Er, Ho, Dy, and Sc) from aqueous solutions. The effect of adsorbent dosage, pH, concentration, contact time, and competing ions on recovery was investigated. Desorption studies were conducted using ammonium sulphate. Adsorption onto zeolite was found to increase with pH, whereas uniform adsorption was observed for bentonite, except at pH 2 (16% less efficiency). The pH values of 6.2 and 3.2 were selected as the optimum for zeolite and bentonite, respectively. For zeolite, the average adsorption efficiencies for REEs at 0.5, 1.0, 2.0, 5.0, and 10 mg L⁻¹ were found to be 91, 96, 89, 40, and 20% respectively but, > 98% adsorption efficiencies were achieved with bentonite at all concentrations. The zeolite and bentonite adsorption data were better described by Langmuir though, for bentonite, the coefficients of determination (R² values) for the Freundlich and Dubinin-Radushkevich isotherm models were also significant. There was no significant difference (p > 0.05) on the adsorption of the elements in the presence of competing ions. Bentonite proved to perform better, most likely as a result of its higher surface area. Generally, the good adsorption performance of both adsorbents in their natural forms makes them an attractive and potential cheap option for the recovery of REEs from wastewaters.

The changes of particles and organic pollutants in indoor atmospheres as consequence of vaping with electronic cigarettes have been analyzed. Changes in the composition of volatile organic compounds (VOCs) in exhaled breath of non-smoking volunteers present in the vaping environments have also been studied. The exposure experiments involved non-vaping (n = 5) and vaping (n = 5) volunteers staying 12 h together in a room (54 m²) without external ventilation. The same experiment was repeated without vaping for comparison. Changes in the distributions of particles in the 8–400 nm range were observed, involving losses of nucleation-mode particles (below 20 nm) and increases of coagulation processes leading to larger size particles. In quantitative terms, vaping involved doubling the indoor concentrations of particles smaller than 10 μm, 5 μm, and 1 μm observed during no vaping. The increase of particle mass concentrations was probably produced from bulk ingredients of the e-liquid exhaled by the e-cigarette users. Black carbon concentrations in the indoor and outdoor air were similar in the presence and absence of electronic cigarette emissions. Changes in the qualitative composition of PAHs were observed when comparing vaping and non-vaping days. The nicotine concentrations were examined separately in the gas and in the particulate phases showing that most of the differences between both days were recorded in the former. The particulate phase should therefore be included in nicotine monitoring during vaping (and smoking). The concentration increases of nicotine and formaldehyde were small when compared with those described in other studies of indoor atmospheres or health regulatory thresholds. No significant changes were observed when comparing the concentrations of exhaled breath in vaping and no vaping days. Even the exhaled breath nicotine concentrations in both conditions were similar. As expected, toluene, xylenes, benzene, ethylbenzene, and naphthalene did not show increases in the vaping days since combustion was not involved.

Nowadays, widespread application of engineered nanoparticles (ENPs) inevitably leads to their release into the environment. Soils are regarded as the ultimate sink for ENPs. The study on mobility of ENPs in soils is important in the assessment of potential risks related to their toxicity. The behavior of ENPs is dependent not only on parameters of soil but also on exposure scenarios, namely, the amount of ENPs trapped in soil. In the present work, the mobility of cerium dioxide nanoparticles (nCeO₂) in soils at different exposure scenarios has been studied. The relationship between mobility of nCeO₂ and their concentration in soil in the range from 1 to 1000 μg g⁻¹ is evaluated. It is shown that the mobility of nCeO₂ decreases with decreasing their concentration in soil and attains the minimum value at the concentration of nCeO₂ below 10 μg g⁻¹. In relative terms, only about 0.1–0.2% of nCeO₂ at their concentration in soil 10–1000 μg g⁻¹ are mobile and can migrate in soil profile under saturated conditions. The major portion of nCeO₂ (about 99.8%) remains immobile in soil. Evidently, the vertical transport of nCeO₂ in soil profile should depend on volume of released suspensions. In the case of small or moderate wet deposition, nanoparticles will accumulate in upper soil horizons, where biological activity is highest, and affect the soil inhabitants (plant roots, earthworms, insects, microorganisms, etc.).

Excess nitrogen in the ecosystem could result in eutrophication and harmful algal bloom in an ecosystem. Low impact development (LID) facilities, regarded as an integral part of green infrastructures for flow control and water quality management may include, but are not limited to, dry/wet ponds, green roof, bioswale or linear ditch, vegetated natural strip, exfiltration trench, piping networks with underdrain or reuse options, and bioswale. This study presents a new approach using a linear ditch along a roadside for LID with the aid of two green sorption media that are designed for co-treatment of stormwater and groundwater for nutrient removal. The stormwater is primarily from agricultural discharge and transportation stormwater runoff. Two recipes of green sorption media, including the green sorption media and woodchip, were examined and compared through a laboratory-scale column study and a field-scale test bed media under various influent concentrations and flow conditions. The green sorption media were found more appropriate than the woodchip media for field-scale applications because the green sorption media may exhibit long-standing microenvironments and hydraulic patterns to provide a homogeneous hydraulic retention time and infiltration rate for nutrient removal. Therefore, such a new LID practice may not only mitigate the impact from various surface stormwater runoffs but also co-treat groundwater and stormwater for nutrient removal.

A new adsorbent poly-3-hydroxybutyrate-2-(dodecylthiocarbonothioylthio)-2-methylpropionate triester (PH-DTT-MPT) was first time loaded in a micropipette tip for speciation of chromium in different water samples. Total chromium (Cr), trivalent chromium (Crᴵᴵᴵ), and hexavalent chromium (Crⱽᴵ) in different natural water samples were determined by electrothermal atomic absorption spectrometry. Known concentration of Crᴵᴵᴵ and Crⱽᴵ was passed through a biodegradable polymer for investigation of the behavior of the newly used adsorbent. The newly used copolymer absorbed the Crᴵᴵᴵ on surface of the PH-DTT-MPT at pH 7.0, while Crⱽᴵ was not adsorbed in desired pH value. After passing the real and standard solutions through the micropipette, then 2.0 mol L⁻¹ HCl was used for elution of Crᴵᴵᴵ from the biodegradable polymer. Total Cr was calculated after reducing Crⱽᴵ into Crᴵᴵᴵ by specific concentration of hydroxy ammonium chloride (HONH₂·HCl). The concentration of Crⱽᴵ in different natural water samples was estimated after back calculation of Crᴵᴵᴵ from total chromium. Effect of analytical parameters like adsorbent, pH, eluent, sample volume, flow rates, and interfering ions was also studied. The LOD, LOQ, RSD, and EF of the developed method were calculated as 6.1 ng L⁻¹, 20 ng L⁻¹, 1.17%, and 90, respectively. Validation of developed method was checked by certified reference materials and spiking addition method. The developed method was successfully applied for determination of total Cr, Crᴵᴵᴵ, and Crⱽᴵ in various natural water ecosystems.

The adverse effects of air emissions from animal feeding operations (AFOs) on public health, environment, and quality-of-life have been well-documented. Regulations or lawsuits may force AFOs to reduce their air emissions. Since livestock barn particulate matter (PM) has relatively high particle density and diameter and many gasses adsorb onto PM, its filtration might reduce air emissions. A porous windbreak wall that imposes acceptable backpressure (< 12.5 Pa) and covers the fan could be a promising option. Seventy-two different porous windbreak wall scenarios were modeled to compare their backpressure on the fan as well as average airspeed over the ground. These scenarios were combinations of shape (box, chamfered, curved), size (lengths of 2, 2.5, and 3 fan diameters), presence or absence of an opening (opened and closed), screen porosity (mosquito screen or clean screen, SunBlocker 70% or clogged screen), and fan angle and height. Backpressure and airspeed decreased with increasing windbreak wall length. Generally, the box-shaped windbreak wall had lower backpressure and airspeeds than the other shapes. The increased backpressure with clogged screen even at two fan diameters (2d) was acceptable. The tilted fan commonly used in poultry houses had higher backpressure and airspeed over the ground than the non-tilted fan used in swine houses due to the former’s lower surface area and tilt towards the ground. Overall, taking into account cost considerations and footprint size (for retrofittability), despite its higher airspeed over the ground (vs. larger footprints) and modest reduction in airflow rate, the 2d, open box model seems the most promising option.

Many organochlorine pesticides (OCPs) are considerably high toxic, and have bioaccumulation potential and chronic adverse impact on both wildlife and human. This study focuses on the fate and metabolic degradation, which is the potential to be more efficient, economic, and safe compared to the aforementioned conventional methods. By these positive attributes, the present work then investigates the capability of newly isolated pathogenic yeast Pichia kluyveri FM012 for biodegradation of DDT in aquatic culture. Pichia kluyveri FM012 mycelia were cultured in a mineral liquid medium consisting of the solution of DDT (40 mg/l) with some experimental conditions such as the initial pH of the culture (5–8), agitation speed (0–150 rpm), and various carbon and nitrogen sources. The highest biodegradation of DDT by Pichia kluyveri FM012 was shown in the culture with pH 5 and 150 rpm agitation. Moreover, the use of glucose and yeast offers the best performance for the degradation compared to other carbon and nitrogen sources. The highest enzyme activity during the decolorization process was dioxygenase. Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, and GC-MS profile showed that the transformation of DDT has occurred. The present DDE and DDD as metabolites of DDT were confirmed by GCMS at a retention time of 17.8 and 16.6 min. The outcomes of this study have several important implications for future practice, for instance in providing an alternative biodegradation agent to remove some organochlorine pollutants.

Diclofenac (DCF) is one of the most widely used non-steroidal anti-inflammatory drugs worldwide, and several studies have reported adverse effects on the environment, in plants and animals; so, it is classified as an emerging pollutant. There are several alternatives for its removal; however, it is necessary to study the way in which the DCF is degrading to offer more effective removal techniques, since the traditional ones such as chlorination, activated sludge, and biofiltration offer low removal efficiency (20–40%). This work analyzes the kinetic behavior of the photodegradation of DCF and the thermodynamic parameters of the reaction under UV-C-type light radiation. The results obtained indicate that it presents a first-order kinetic promoted by the increase of the temperature. Also, within the evaluated interval (273 to 308 K), the values of the kinetic coefficient (k) range between 0.05 and 0.20 min⁻¹ and the half-life ranges from 3 to 9 min. The reaction is exothermic and spontaneous and gives way to the formation of approximately 6 byproducts, being two with the greatest presence and stability. This suggests that its decomposition route occurs through the dechlorination of the molecule and originate compounds known as carbazoles that have been detected in previous works. It was also found that this mixture of byproducts remained after the degradation of the drug, which is released to the environment, so it is necessary to extend a study on its properties and its possible environmental impact.