Vast areas of Europe were contaminated by the fallout of ¹³⁷Cs and other radionuclides, as a result of the Chernobyl accident in 1986. The post-fallout redistribution of Chernobyl-derived ¹³⁷Cs was associated with erosion and sediment transport processes within the fluvial system. Bottom sediments from lakes and reservoirs can provide a valuable source of information regarding the post-fallout redistribution and fate of ¹³⁷Cs released by the Chernobyl accident. A detailed investigation of sediment-associated ¹³⁷Cs in the bottom sediments of a reservoir in a Chernobyl-affected area in Central Russia has been undertaken. A new approach, based on the vertical distribution of ¹³⁷Cs activity concentrations in the reservoir bottom sediment makes it possible to separate the initially deposited bottom sediment, where the ¹³⁷Cs activity reflects the direct fallout of Chernobyl-derived ¹³⁷Cs to the reservoir surface and its subsequent incorporation into sediment deposited immediately after the accident, from the sediment mobilized from the catchment deposited subsequently. The deposits representing direct fallout from the atmosphere was termed the “Chernobyl peak”. Its shape can be described by a diffusion equation and it can be distinguished from the remaining catchment-derived ¹³⁷Cs associated with sediment accumulated with sediments during the post-Chernobyl period. The ¹³⁷Cs depth distribution above the "Chernobyl peak" was used to provide a record of changes in the concentration of sediment-associated ¹³⁷Cs transported from the upstream catchment during the post-Chernobyl period. It was found that the ¹³⁷Cs activity concentration in the sediment deposited in the reservoir progressively decreased during the 30-year period after the accident due to a reduction in the contribution of sediment eroded from the arable land in the catchment. This reflects a reduction in both the area of cultivated land area and the reduced incidence of surface runoff from the slopes during spring snowmelt due to climate warming.

This paper reports the chemical and light extinction characteristics of fine aerosol (PM₂.₅) during the winter period (2017–18) at Lumbini, Nepal, a rural site on the Indo Gangetic Plains. A modified IMPROVE algorithm was employed to reconstruct light extinction by chemical constituents of aerosol. The fine aerosol levels impacted visibility adversely during daytime, but during nighttime visibility was controlled by fog droplets rather than by aerosols. The PM₂.₅ chemical constituents showed varying characteristics during clear and polluted days. The average NO₃⁻/SO₄²⁻ concentration ratio was 0.57 during clear and 1.36 and polluted days, signifying a change in secondary inorganics and formation processes mainly due to decreasing photochemical production and due to increased partitioning of nitrate particles at a lower temperature. The increased secondary organics contribution and the higher OM/OC ratio (2.2) during polluted days showed the vital role of aqueous processing and biomass burning emissions in determining the concentration of organics. Total light extinction was 2.3 times higher on polluted days compared to clear days, while the PM₂.₅ mass concentration was 1.5 times higher. This variation in mass and extinction order signifies that various chemical components in fine particles have a more considerable impact on light extinction. On clear days we found that carbonaceous particles (OM and EC) made a major contribution to light extinction. In contrast, the extinction contribution by secondary inorganic (especially NH₄NO₃) increased significantly during polluted days, with hygroscopic growth and enhanced scattering efficiency at higher RH conditions playing a major role. The comparison between clear and polluted days altogether suggests that regulating the nitrate sources can help significantly in improving the visibility levels and restrict fog haze development during wintertime in rural IGP.

The influence of common textile finishes on cotton fabrics on the generation of microfibers during laundering was assessed. Microfiber release was determined to be in the range of 9000–14,000 particles per gram of cotton fabric. Cotton knitted fabrics treated with softener and durable press generate more microfibers (1.30–1.63 mg/g fabric) during laundering by mass and number than untreated fabric (0.73 mg/g fabric). The fabrics treated with softener generated the longest average microfiber length (0.86 mm), whereas durable press and water repellent treatments produced the shortest average microfiber length (0.62 and 0.63 mm, respectively). In general, the changes in the mechanical properties of the fibers and fabrics due to the finishing treatments are the main factor affecting the microfiber release. The abrasion resistance of the fabrics decreases for durable press treatments and water repellent treatments due to the brittleness in the structure originated by the crosslinking treatment. In the case of the softener treatment, the fabric surface is soft and smooth decreasing the friction coefficient between fibers favoring the fibers loosening from the textile and resulting in a high tendency for fuzz formation and microfiber release. These findings are useful for the textile industry in the design and selection of materials and treatments for the reduction of synthetic or natural microfiber shedding from textiles.

In this study, a sustainable NH₂-MIL-101(Al) is synthesized and subjected to characterization for cryogenic CO₂ adsorption, isotherms, and thermodynamic study. The morphology revealed a highly porous surface. The XRD showed that NH₂-MIL-101(Al) was crystalline. The NH₂-MIL-101(Al) decomposes at a temperature (>500 °C) indicating excellent thermal stability. The BET investigation revealed the specific surface area of 2530 m²/g and the pore volume of 1.32 cm³/g. The CO₂ adsorption capacity was found to be 9.55 wt% to 2.31 wt% within the investigated temperature range. The isotherms revealed the availability of adsorption sites with favorable adsorption at lower temperatures indicating the thermodynamically controlled process. The thermodynamics showed that the process is non-spontaneous, endothermic, with fewer disorders, chemisorption. Finally, the breakthrough time of NH₂-MIL-101(Al) is 31.25% more than spherical glass beads. The CO₂ captured by the particles was 2.29 kg m⁻³. The CO₂ capture using glass packing was 121% less than NH₂-MIL-101(Al) under similar conditions of temperature and pressure.

One of the worst socio-environmental disasters to mark the history of Brazil and the world occurred in November 2015 and involved the mining sector. The collapse of the Fundao dam released approximately 43 million m³ of iron ore tailings, which moved downstream to reach the Doce River. This resulted in the contamination of water, soil, and sediments along the entire course of the river, which also affected its mouth in the Atlantic Ocean. Four years after the disaster, several socio-environmental problems continue to persist in the affected areas. In this context, the reservoirs built along the Doce River deserve special attention as they are artificial environments that are highly vulnerable to changes in water parameters. This study aims to determine water quality indicators of these reservoirs using remote sensing data and image processing methods, including semi-analytical algorithms, to comprehend the progress of eutrophication processes. Operational land imager/Landsat-8 data (from 2013 to 2019) were used to map the suspended particulate matter (SPM), euphotic zone (Zₑᵤ) and chlorophyll-a (Chl-a) before and after the collapse. The results showed significant changes in SPM and Zₑᵤ in the reservoirs after the collapse. Non-conformity of these parameters is observed even now, and they tend to intensify during rainy periods when resuspension processes of sediments occur. Moreover, there has been an increase in the eutrophication of reservoirs as noticed by the significant increase in Chl-a after the disaster, especially in January, July, and August.

Cellulose acetate (CA) is one of widely used polymers for chemical and medical applications due to its versatile physico-chemical functionalities. Although its recycle is available after a deacetylation process, the recycle process releases a huge amount of wastewater. Thus, this study investigated a direct disposal process of CA with its valorization to syngas (H₂ and CO) through pyrolysis. To construct more environmentally benign process, CO₂ was used as a co-feedstock with CA to simultaneously convert them into syngas. Pyrolysis of CA in N₂ was performed as a reference study to examine the effectiveness of CO₂ on valorization of CA. Acetic acid and methyl acetate were main volatile pyrolysates (VPs) from CA pyrolysis, and the further thermal cracking of VPs resulted in syngas and CH₄ formations under both N₂ and CO₂ conditions. To expedite syngas formations, multi-stage pyrolysis (two-stage pyrolysis) and catalytic pyrolysis were employed. With the increased thermal energy through two-stage pyrolysis, four times more production of syngas was shown, comparing to the result of a single-stage pyrolysis. With Ni catalysts, the syngas formation was the two orders of magnitude higher than the single-stage pyrolysis, and the significant enhancement of CO formation was shown in the presence of CO₂ due to combined effects of CO₂ and the Ni-based catalysts. This CO enhancement resulted from catalytically expedited gas phase reactions between CO₂ and VPs evolved from CA. In addition, the CO₂ contributed to the suppression of coke deposition on the catalyst, thereby suggesting more technical and environmental benefits of CO₂ as a reactive co-feedstock of pyrolysis in reference to N₂. Therefore, this study proved the direct and versatile technical platform to convert CA and CO₂ into syngas.

In developing countries, urban areas may be at greater risk of pesticide exposure compared to semi-urban agricultural regions. To investigate this, concentrations of selected pesticides were measured in 81 human milk samples collected in urban Kolkata and semi-urban Nadia in West Bengal, India. Three classes of pesticides were investigated – legacy organochlorines and emerging pyrethroids and neonicotinoids. The average concentration of the majority of the chemicals (DDT, its metabolites, HCH isomers, bifenthrin, endosulfan), showed a clear urban > semi-urban trend. Compared with previous measurements in other Indian cities and developing nations, current HCH and DDT concentrations in urban Kolkata were high. These chemicals were detected in 100% of the samples in both the urban and the semi-urban region. Also in both regions, the Estimated Daily Intake of DDTs, HCHs, aldrin, dieldrin and the pyrethroid bifenthrin for breastfed infants exceeded the Tolerable Daily Intake in a number of samples. Three pyrethroids were detected in human milk samples in India for the first time. This indicates a shift in the usage pattern of pesticides in India from organochlorines to pyrethroids. These findings may be used to drive targeted regulation of pesticides in developing countries with similar histories of pesticide use.

The study of emissions and depositions of atmospheric reactive nitrogen species (Nᵣs) in a region is important to uncover the sources and sinks of atmospheric Nᵣs in the region. In this study, atmospheric total Nᵣs depositions including both wet-only and dry deposition were monitored simultaneously across major land-use types in a 105 km² catchment called Jinjing River Catchment (JRC) in subtropical central China from 2015 to 2016. Based on activity data and emission factors for the main Nᵣs emission sources, ammonia (NH₃) and nitrogen oxides (NOₓ) emission inventories for the catchment were also compiled. The estimated total Nᵣs deposition in JRC was 35.9 kg N ha⁻¹ yr⁻¹, with approximately 49.7 % attributed to reduced compounds (NHₓ), and 40.5 % attributed to oxidized (NOy). The total Nᵣs emission rate in JRC was 80.4 kg N ha⁻¹ yr⁻¹, with 61.5 and 18.9 kg N ha⁻¹ yr⁻¹ from NH₃ and NOₓ emissions, respectively. Livestock excretion and fertilization were the two main contributing emission sources for NH₃, while vehicle sources contributed the bulk of NOₓ emissions. The net atmospheric budgets of Nᵣs in paddy field, forest, and tea field were +3.7, −36.1, and +23.8 kg N ha⁻¹ yr⁻¹, respectively. At the catchment scale, the net atmospheric budget of Nᵣs was +47.7 kg N ha⁻¹ yr⁻¹, with +43.7 kg N ha⁻¹ yr⁻¹ of NHₓ and +4.0 kg N ha⁻¹ yr⁻¹ of NOy, indicating that the subtropical catchment was net sources of atmospheric Nᵣs. Considering that excessive atmospheric Nᵣ emissions and deposition may cause adverse effects on the environment, effects should be conducted to mitigate the Nᵣs emissions from agriculture and transportation, and increasing the area of forest is good for reducing the net positive budget of atmospheric Nᵣs in the subtropical catchments in China.

To identify the role of gut microbiota in human health risk assessment, the bioaccessibility of heavy metals in 14 soil samples were determined in simulated gastrointestinal fluids. Compared to the small intestinal phase, the bioaccessibility values of the colon phase varied, either increased by 3.5-fold for As, by 2.2-fold for Cr, and by 1.6-fold for Ni, or reduced by 4.4-fold for Cu, respectively. The colon incubation with adult gut microbiota yielded higher bioaccessibility value of As (1.3 times) and Fe (3.4 times) than that of the child in most soil samples. Colon bioaccessibility was about 60% greater of Cd for the adult and 30% higher of Cr for the child. Congruent data on the bioaccessibility of Cu and Ni was observed. In addition, correlation analysis indicated that in vitro bioaccessibility was primarily related to total concentrations of heavy metals in soils, followed by soil pH and active Fe/Mn oxide. Significantly, risk assessment calculated based on colon bioaccessibility indicated that the target hazard quotient (THQ > 1) of As was presented in 3 soil samples for the adult (1.05–3.35) and in 9 soil samples for the child (1.06–26.93). The hazard index (HI) of the child was 4.00 on average, greater than that of the adult (0.62), primarily due to the contribution of As and Cd. It suggested non-carcinogenic risks are likely to occur in children through typical hand-to-mouth behavior. The adjustment of colon bioaccessibility will result in more accurate risk assessment of human exposure to heavy metals from oral ingestion of contaminated soils.

Satellite-derived aerosol optical depth (AOD) has been widely used to predict ground-level fine particulate matter (PM₂.₅) concentrations, although its utility can be limited due to missing values. Despite recent attempts to address this issue by imputing missing satellite AOD values, the uncertainty associated with the AOD imputation and its impacts on PM₂.₅ predictions have been understudied. To fill this gap, we developed a missing data imputation model for the AOD derived from the Multi-Angle Implementation of Atmospheric Correction (MAIAC) and PM₂.₅ prediction models using several machine learning methods. We also examined how the uncertainty associated with the imputed AOD and a choice of machine learning algorithm were propagated to PM₂.₅ predictions. The application of the proposed imputation model to the data from New York State in the U.S. achieved a superior performance than those related studies, with a cross-validated R² of 0.94 and a Root Mean Square Error of 0.017. We also found that there was considerable uncertainty in PM₂.₅ predictions associated with the use of imputed AOD values, although it was not as high as the uncertainty from the machine learning algorithms used in PM₂.₅ prediction models. We concluded that the quantification of uncertainties for both AOD imputation and its propagation to AOD-based PM₂.₅ prediction is necessary for accurate and reliable PM₂.₅ predictions.