Environments, Volume 10, Issue 8 (August 2023) – 17 articles

The development of efficient heterogeneous persulfate activators is one of the main research topics in the wastewater treatment area. The present work deals with the heterogeneous activation of sodium persulfate (SPS) using nickel oxide/strontium carbonate (NiO/SrCO₃) for the degradation of sulfamethoxazole (SMX), a representative compound from the group of antibiotics. Results showed that NiO/SrCO₃ exhibited high performance towards the activation of SPS, leading to SMX elimination in brief time spans. The impact of SPS (25–100 mg/L), NiO/SrCO₃ (50–250 mg/L), and SMX (0.25–3.00 mg/L) concentration, and initial pH on the decomposition of SMX was further examined. Experiments were also conducted in real matrices such as secondary effluent and bottled water, revealing the existence of retarding phenomena compared to ultrapure water. This behavior was further investigated with the addition of bicarbonates, chlorides, or humic acid in ultrapure water. It was found that organic matter significantly hampered SMX removal. The role of the main radicals (hydroxyl and sulfate radicals) was determined using appropriate radical traps (methanol and tert-butanol). These quenching experiments combined with the conducted electrochemical measurements revealed that both a radical and a non-radical mechanism contribute to the decomposition of SMX. Full article

Recently, due to rapid industrialization and urbanization, many studies have focused on the assessment of soil metal contamination. The present research aimed to investigate the concentration of potentially hazardous elements (Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, V and Zn) in three different areas (forest, wildfire forest and urban) of the Mediterranean region. Contamination levels were further assessed calculating different indices: contamination factor (CF), geo-accumulation index (GI) and ecological risk (E). The results showed high concentrations of V, Mg and Mn in forest and wildfire forest soils, as well as high concentrations of Al, Fe, Ni, Pb and Zn in urban soils. According to the contamination indices, Pb exceeded the background level in both wildfire forest and urban soils. According to human risk assessment, inhalation appeared the main route of exposure of metals in soils, especially for children. The overall cancer risk was higher than the safe level, especially for Pb. Different relationships were found between the contamination indices and the potential risk of carcinogenic effects according to the diverse metal concentrations. Particularly, wildfire soils showed human health risks mainly linked to Pb, Cu and Cr contaminations, due to human activities, and Ni, due to both anthropogenic and pedogenetic input. Instead, the urban soils showed that Zn contamination, mainly related to urban traffic, influenced the potential carcinogenetic risk in this area. The carcinogenic risk was higher than acceptable values for all the metals assessed. These findings highlighted the need to develop further management practices to protect soils from metal pollution and reduce human health risks. Full article

Birds are commonly used as bioindicators, and their feathers are considered suitable tissues for assessing the presence of contaminants, such as trace elements, in the environment. In agroecosystems, trace elements’ occurrence can be associated with both natural and anthropogenic processes, including vehicular traffic, traditional fertilizers, food feed additives for livestock, and the use of sewage sludge as fertilizer. Here, we evaluated the concentrations of twelve trace elements (Aluminium, Arsenic, Cadmium, Chromium, Copper, Iron, Mercury, Manganese, Nickel, Lead, Selenium, and Zinc) in the feathers of barn swallow (Hirundo rustica) nestlings. We then compared the concentrations of these elements between nestlings grown in areas amended or not amended with sewage sludge in 2019 and 2020 in a broad region of the Po Plain (Northern Italy). Multivariate analysis showed that the element content of the feathers significantly differed among years and areas, suggesting that the concentration of nestlings’ feathers may indicate the local level of contamination. However, univariate analyses did not show clear spatial differences, possibly due to co-occurring sources of trace elements other than sewage sludge. These results suggest that barn swallow nestlings can be a reliable sentinel for the monitoring of local variation of the environmental occurrence of trace elements. Full article

Although beef production is one of the most valuable drivers of the global livestock economy, it is considered the main contributor to GHG emissions derived from livestock. This study’s objectives were to estimate the GHG emissions (expressed in carbon dioxide equivalents; CO₂-eq) from the beef sector in Greece at the national and prefecture levels during the period 2011–2021 and to explore potential mitigation scenarios. The Tier 1 and 2 methodologies were implemented to estimate the GHG emissions. The total estimated emissions increased over the study period. Although both methodologies captured similar trends in the changes in GHG emissions, the Tier 2 estimations revealed lower emissions and fluctuations due to the different and more precise computational approaches. At the prefecture level, fluctuations in emissions were also noted. However, specific regions showed higher increases in emissions. The observed increase in emissions, in terms of either absolute values (Gg CO₂-eq) or intensities (Kg CO₂-eq/Kg produced beef carcass), is of utmost importance, and further mitigation strategies should be considered. The regression analysis showed a good predictive ability for emissions, using the number of livestock animals as the input. The equations derived from this analysis could be further used as first-approach tools for capturing future emissions at the national level before proceeding with more elaborate approaches. The different scenarios examined in response to the sector’s challenges showed moderate changes in GHG emissions. Depending on national priorities, such scenarios could serve as pilot case studies, which may assist stakeholders in improving the sustainability of the sector in the future. Full article

Freshwater reservoirs constitute an important source of drinking water, but eutrophication and higher temperatures increase the risk of more frequent blooms of cyanobacteria, including species that produce toxins. To improve the prediction of cyanotoxin episodes, we studied the annual occurrence of potential microcystin (MC) and saxitoxin (STX)-producing cyanobacteria in the Lobo reservoir, São Paulo State, Brazil. Relationships among environmental variables, cyanobacterial biomass, numbers of the mcyE and sxtA genotypes (genes encoding production of MC and STX, respectively), and concentrations of MC and STX were determined to address variables applicable for monitoring and predicting the dynamics of cyanobacteria and cyanotoxins in the reservoir. Microscopy confirmed the presence of potentially toxin-producing cyanobacteria at all sampling times, and qPCR detection showed the occurrence of both mcyE and sxtA in most samples. Concentrations of MC and STX were generally low (MC 0–1.54 µg L⁻¹; STX 0.03–0.21 µg L⁻¹). The highest MC level exceeded the recommended limit for human intake of 1 µg L⁻¹. The abundance of the mcyE and sxtA genes, as well as the toxin concentrations, were positively correlated with the biomass of Phormidium and Raphidiopsis. Among environmental variables, the abundance of potential toxic cyanobacteria was mainly affected by P limitation (high TN:TP ratios). Our data show that detection of the mcyE and sxtA genotypes serves as a useful and reliable predictor of toxin episodes but might be combined with chemical toxin detection to form an environmental toolbox for cyanotoxin monitoring. Full article

Waste-grade cork samples of Quercus cerris were subjected to maceration extraction using 7 different solvents, including pure water (I), pure acetone (II), 75% aqueous ethanol (III), 75% aqueous methanol (IV), 75% aqueous acetone (V), 50% aqueous acetone (VI), and 25% aqueous acetone (VII). The extract yields, extract compositions, as well as antioxidant and antimicrobial activities of the extracts were analyzed. The results showed that maceration extraction was highly efficient, particularly with binary solvents resulting in up to 6% extract yield and up to 488 mg GAE/g extract total phenolic content. The extracts exhibited a variable antioxidant activity determined by DPPH and FRAP methods as well as antimicrobial activity against gram-positive bacteria and fungus determined by agar diffusion test. The CIELAB color parameters of extracts were correlated with maceration time, and the correlation was highest with pure water extracts. The FT-IR spectra of acetone-extracted cork revealed six key markers of phenolic compounds with the presence of peaks at approximately 2920 cm⁻¹, 2850 cm⁻¹, 1609 cm⁻¹, 1517 cm⁻¹, 1277 cm⁻¹, and 1114 cm⁻¹. The overall results suggest that the maceration of waste cork in binary solvents and pure acetone are green alternatives to conventional Soxhlet extraction for the production of polar extracts. Full article

The effect of bad air quality on human health is a well-known risk. Annual health costs have significantly been increased in many countries due to adverse air quality. Therefore, forecasting air quality-measuring parameters in highly impacted areas is essential to enhance the quality of life. Though this forecasting is usual in many countries, Sri Lanka is far behind the state-of-the-art. The country has increasingly reported adverse air quality levels with ongoing industrialization in urban areas. Therefore, this research study, for the first time, mainly focuses on forecasting the PM₁₀ values of the air quality for the two urbanized areas of Sri Lanka, Battaramulla (an urban area in Colombo), and Kandy. Twelve air quality parameters were used with five models, including extreme gradient boosting (XGBoost), CatBoost, light gradient-boosting machine (LightBGM), long short-term memory (LSTM), and gated recurrent unit (GRU) to forecast the PM₁₀ levels. Several performance indices, including the coefficient of determination (R²), root mean squared error (RMSE), mean absolute error (MAE), mean squared error (MSE), mean absolute relative error (MARE), and the Nash–Sutcliffe efficiency (NSE), were used to test the forecasting models. It was identified that the LightBGM algorithm performed better in forecasting PM₁₀ in Kandy (${\mathrm{R}}^2=0.99, \mathrm{MSE} =0.02, \mathrm{MAE}=0.002, \mathrm{RMSE} =0.1225, \mathrm{MARE} =1.0, \mathrm{and} \mathrm{NSE}=0.99)$. In contrast, the LightBGM achieved a higher performance (${\mathrm{R}}^2=0.99, \mathrm{MSE} =0.002, \mathrm{MAE} =0.012 , \mathrm{RMSE} =1.051, \mathrm{MARE} =0.00, \mathrm{and} \mathrm{NSE}=0.99)$ for the forecasting PM₁₀ for the Battaramulla region. As per the results, it can be concluded that there is a necessity to develop forecasting models for different land areas. Moreover, it was concluded that the PM₁₀ in Kandy and Battaramulla increased slightly with existing seasonal changes. Full article

Ammonia-nitrogen (NH₃-N) loss from agriculture decreases crop yield potential and environmental quality. Incorporating animal manures by chisel plowing (CP) can reduce NH₃ loss but may increase crop residue loss compared to lower disturbance incorporation methods and vertical tillage (VT). Few studies have evaluated VT efficacy for incorporating manure and reducing NH₃ concentrations compared to traditional tillage tools, such as CP. Six trials during 2013 to 2016 were conducted to evaluate the impacts of manure incorporation method (CP, VT, or broadcast) and weather conditions at the time of application on NH₃-N concentrations at a dairy research farm in central Wisconsin, USA. Passive samplers measured NH₃-N concentrations at 30-cm above the ground during the first 0 to 24 and 24 to 48 h post-manure application/incorporation. Average NH₃-N concentrations for CP and VT were 44 to 86% of broadcast and similar for most trials, while crop residue coverage for VT was greater than CP (39 and 22% of control plots, respectively). Concentrations of NH₃-N were correlated with the amount of plot area covered by manure for the first (r = 0.56, p < 0.0001) and second measurement periods (r = 0.85, p < 0.0001). Results show that VT had comparable NH₃-N concentration reductions to CP while conserving more crop residue. Full article

The EN 1793-5 and EN 1793-6 standards have been in use for many years as a method for measuring the intrinsic characteristics of noise barriers installed along highways and railways. They require a sound source and a grid of microphones, to be placed near the barrier and in free field conditions, according to predetermined distances. In principle, small errors in positioning the sound source and microphone grid may affect the results obtained. An international round-robin test was carried out in 2012 to evaluate the repeatability and reproducibility of the method, but until now no studies have been carried out to evaluate and compare the repeatability of laboratory versus in-place measurements performed with the same equipment and its variance when an imperfect positioning of sound source and microphones is taken into account. In the present work, multiple series of sound reflection index and sound insulation index measurements performed on noise barriers of the same kind installed in the laboratory or along a highway are presented. The measurements were repeated in different ways: (1) in the laboratory, leaving the source and microphones unmoved to assess the repeatability of the results and of the measurement system under controlled conditions; (2) in the laboratory, repositioning for each measurement the source and microphone grid to assess the robustness of the method under real conditions but in a controlled environment; (3) in situ, along a highway open to traffic, repositioning for each measurement the source and microphone grid to assess the repeatability of the method under real conditions in a critical environment. In both reflection index and sound insulation index measurements, the standard deviation on single-number ratings in all cases examined is well below the value presented in EN 1793-5 and EN 1793-6, which was obtained from statistical analysis of the international round-robin test performed a dozen years ago, suggesting that expert operators with state-of-the art equipment can achieve much better results now. Full article

An increase in population along the Indian River Lagoon has led to eutrophication, a decline in water quality, and overall degradation. The Living Docks program is a citizen–science initiative started at the Florida Institute of Technology for lagoon restoration. Public and private docks are volunteered to become Living Docks, where oyster mats are attached to dock pilings to provide a natural substrate for benthic organism growth. The community development on the oyster mats boosts water filtration to improve overall water quality and combat anthropogenic effects on the lagoon. The purpose of this project was to model benthic settlement and recruitment of prominent organisms on the Living Dock oyster mats at four research sites with specific environmental factors (e.g., temperature, salinity, turbidity, and pH). Beta regression models for recruitment and settlement were created for five of the more dominant organisms observed: oyster, barnacle, sponge, tubeworm, and encrusting bryozoan. The results of the modeling indicated that the settlement was influenced by pH, salinity, dock location, and turbidity, while recruitment was influenced by pH, salinity, dock location, and immersion time. This project provides insight into how lagoon conditions surrounding the Living Docks impact benthic growth and can aid in IRL restoration. Full article

Eggs represent one of the most consumed animal products worldwide. In Europe, over 366 million laying hens and 6.1 Mt of derived eggs have been estimated in 2020, and Italy represents the fourth largest producer (41 million hens and 0.79 Mt of eggs). Egg production has been identified as relatively environmental-friendly, but several environmental concerns have been recently raised considering the inefficient spent hens’ management. Spent hens are generally euthanized and composted or incinerated, producing greenhouse gases while at the same time significant nutrients are lost. First, the research reviews the egg supply chain characteristics and the alternative spent hens’ valorization pathways. Then, using the material flow analysis, the research quantifies and qualifies the consistencies of laying hens and protein content included in spent hens across Italy, providing a comprehensive assessment of the national scenario under an environmental and circular perspective. Furthermore, the research develops an inventory of the spent hens’ co-products and by-products in Italy, focusing on the flows of proteins for further environmental studies. The research has highlighted that over 13,948 t of proteins could be extracted, distinguishing between those embedded within offal, feathers and blood. In addition, spent hens can be used for human consumption, as well as for material or energy recovery through anaerobic digestion or microbial fermentation. Results are addressed to farmers, who are required to boost their environmental performances, and public authorities, who must implement sustainable strategies to collect spent hens. Full article

Quantifying the burden of disease from exposure to poor indoor air pollution can support policy development. In England, there is current regulatory and public attention on the health implications of residential exposure to formaldehyde, damp and mould. However, there is scarce information on these health impacts at the population scale. As such, we assessed the burden of key respiratory diseases from residential formaldehyde, damp and/or mould for the English population aged 0–14 and 15–49. We obtained data on the percentage of dwellings affected by damp and/or mould from the English Housing Survey and estimated the distribution of residential formaldehyde concentrations (annual average (μg/m³)) by pooling data from monitoring studies conducted in England. Exposures were combined with epidemiological relationships and national health data to estimate Population Attributable Fractions (PAFs), disease incidence, and Disability Adjusted Life Years (DALYs) lost associated with residential formaldehyde or damp and/or mould exposure in England. We made estimates for the year 2019 but also looked back several years in time. Exposure to formaldehyde was associated with approximately 4000 new cases of childhood asthma (~800 DALYs lost) in 2019, though the estimates were sensitive to the placement of the lower exposure threshold. Exposure to damp and/or mould was associated with approximately 5000 new cases of asthma (~2200 DALYs) and approximately 8500 lower respiratory infections (~600 DALYs) among children and adults in 2019, though the PAFs were unequally distributed across dwellings based on income and ethnicity. Alternative data sources suggest that the percentage of dwellings affected by damp and/or mould may even be higher, resulting in a possible 3–8-fold greater number of cases and DALYs. Our assessment emphasizes a potential respiratory health burden in England associated with residential formaldehyde as well as damp and/or mould, further highlighting the public health importance of good indoor air quality and good quality housing. Full article

Emissions and by-products from manufacturing torrefied solid recovered fuel using pulp industry waste containing wood waste with pulp sludge (WPS) were studied. Two batches of WPS1 and WPS2 were tested. The torrefaction of WSP1 and WPS2 were performed at their respectively optimal temperature of 573 and 593 K and time of 20 min, referred as cases WPST1-573-20 and WPST2-593-20, respectively. WPS1 contained higher fixed carbons and volatile matters but lower ash content than WPS2. The results showed that the solid yields of 56 and 61 wt.%, gas yields of 16 and 16 wt.% and liquid yields of 28 and 24 wt.% for WPST1-573-20 and WPST2-593-20, respectively. The maximal concentration of emissions for WPST1-573-20 and WPST2-593-20 are about 1952.5 and 3743.5 ppmv for CO, 26.5 and 156 ppmv for NO_x and 31.5 and 392 ppmv for SO₂, respectively. The C_CO exceeded the emission standard and required further action. The collected non-condensable gases consisted of hydrocarbons ranging from C1-HC to C6-HC, with C4-HC being the predominant component. Here, Cn-HC represents hydrocarbons with a carbon atom count of n. The GC-MS analysis revealed the primary liquid byproducts. The liquid products can be used directly as pyroligneous liquor in agriculture. Furthermore, with refining techniques, these liquid byproducts can be transformed into high-quality chemicals for applications such as fungicides, pesticides, solvents, surfactants, and as precursors or monomers in the synthesis of other chemicals. Full article

This study established a study framework to quantify the safety factors of unsaturated shallow slopes at different temperatures. This study is based on a non-isothermal soil water characteristic curve model quantifying the temperature-dependent hydraulic properties of soils. The hydraulic coupling analysis models HYDRUS 2D and The Slope Cube Module were used for finite element modeling. A slope stability analysis was performed based on the local factor of safety (LFS) theory. An increased temperature decreased the soil matric suction, suction stress, effective stress, and LFS, weakening the soil strength. Slope modeling analysis showed that soils were dominated by different water retention mechanisms before and after rainfall infiltration, and the trends caused by temperature changes also changed accordingly. This study provides insights into the relationship between soil mechanical properties and temperature, which is valuable for maintaining soil stability and preventing geological hazards. Full article

Intertidal reefs of Crassostrea virginica (eastern oyster) provide ecologically valuable habitat in estuaries along the Atlantic coast of North America. In Mosquito Lagoon, a shallow-water estuary on the east coast of central Florida, USA, historical aerial imagery was used to document a 24% decline in the live C. virginica reef area between 1943 and 2009. Using 2021 imagery, every living and dead reef in the same region was manually digitized to identify changes during the intervening 12 years. Positive impacts of C. virginica reef restoration that took place between 2007 and 2021 were also digitized to quantify long-term restoration impact. Natural, live C. virginica reef coverage throughout the system was found to have decreased by 50.6% between 2009 and 2021 and, thus, 62.6% between 1943 and 2021. This was attributed to reef fragmentation, reef footprint loss, boating activity, and mangrove expansion. Of the 2542 live reefs identified using 2009 imagery, 219 reefs fragmented, 988 reefs no longer had an identifiable footprint, and 598 reefs contained visible mangroves with non-continuous canopies. Conservatively, 63.6% of directly restored reef area was classified as living reef in 2021, and 74.5% of restoration projects were more than 50% live reef. Dead reef area decreased by 57.9% throughout the system. Understanding changes in C. virginica reef acreage, reef numbers, and mangrove expansion is essential for resource management, restoration practices, and tracking climate change impacts on publicly protected estuaries. Full article

Acid mine drainage was utilized to catalyze the solar photo-Fenton treatment of wastewater coming from a sludge dewatering system. Acid mine drainage in the form of iron-rich liquid or synthesized minerals (namely magnetite, hematite, and goethite) was added in the wastewater, which was treated by means of the solar photo-Fenton process. The effects of operational parameters such as the amount of acid mine drainage, the wastewater matrix (i.e., synthetic and real wastewater), and the initial H₂O₂ concentration municipal wastewater’s organic content were explored. The results showed that using acid mine drainage (liquid phase) for wastewater treatment was more efficient than using the acid-mine-drainage-recovered minerals. Moreover, it was observed that the addition of acid mine drainage above 10.7 mL/L wastewater, which is equivalent to 50 mg/L iron, could substantially reduce the removal percentage of the chemical oxygen demand (COD). At the best conditions assayed, COD removal reached 99% after 90 min of photo-Fenton treatment under simulated solar light, in the presence of 30 mg/L Fe (i.e., 6.4 mL drainage/L of real wastewater) and 1000 mg/L H₂O₂ at a pH of 2.8. Therefore, the solar photo-Fenton treatment of municipal wastewater catalyzed by acid mine drainage may appear to be a promising method to effectively improve wastewater management, especially in areas with high solar energy potential. Full article

Soil is continuously excavated for development activities in urban and rural areas and treated as waste. This study investigates the characteristics of urban soils excavated from earthworks of buildings in the Brittany region of France for their perspective reuse in earthen construction materials to valorize soil waste and provide a sustainable building material locally. Excavated soil from earthwork activities was taken from the Brittany region of France from three different locations. Soil suitability for compressed earth blocks was investigated based on their granulometry, consistency limits, and mineralogy. Finally, compressed earth blocks with dimensions of 4 × 4 × 16 cm³ were manufactured with different formulations and compacted dynamically. Flexural and compressive strength tests were performed on bricks to observe their mechanical behavior. Grain size analysis of soil samples shows that the percentage of clay in the landfill stockpile of excavated soils varies between 13% and 16%, while at some local sites, the percentage of clay goes up to 57%. The grain size of soils varies from the recommended zone. The plasticity of soil samples ranges from 17.3% to 20.4%. The plasticity index and clay content of the soil show that these soils are inactive clays with a lesser possibility of swelling and shrinkage. Mineralogical analysis of soil shows the absence of water-sensitive clay minerals, while quartz, kaolinite, and illite are major minerals present in soils. Linear shrinkage in bricks ranges from 0.6% to 2.2% and is considerably higher for clayey soils. Mechanical testing of earth bricks shows that the compressive strength of earth blocks ranges from 0.92 MPa to 2.22 MPa while the flexural strength ranges from 0.25 to 0.74 MPa. A mixture of sandy and clayey soils shows good strength due to improved granulometry. Earth bricks with soils from some stockpiles, excavation sites, and soil mixture show compressive strength higher than 1 MPa, which is recommended strength by international standards, and offer the opportunity to produce sustainable building materials locally. Full article