Environmental Science: Processes & Impacts最新文献

In surface waters, photodegradation is a major abiotic removal pathway of the neurotoxin monomethylmercury (MMHg), acting as a key control on the amounts of MMHg available for biological uptake. Different environmental factors can alter the rate of MMHg photodegradation. However, our understanding of how MMHg photodegradation pathways in complex matrixes along the land-to-ocean aquatic continuum respond to changes in salinity, dissolved organic carbon (DOC) concentration and dissolved organic matter (DOM) composition is incomplete. In a set of laboratory experiments combining several artificial and natural waters, we demonstrate that the interplay of DOC concentration, DOM composition, and salinity affects the photodegradation rate of MMHg. The presence of DOM was found to facilitate MMHg photodegradation, but degradation rates were not altered by varying DOC concentrations over two orders of magnitude. We found DOM composition to have a stronger effect on MMHg photodegradation rates than DOC concentration. However, at high DOC levels, where most UV radiation was lost within the first cm of the reaction vessels, lower MMHg photodegradation rates were observed. When moving from terrestrially influenced waters, characterized by a high degree of humification, towards marine conditions with a protein-rich DOM pool, MMHg photodegradation rates increased. In contrast, salinity had a stabilizing effect on MMHg. Hence, especially in systems with low salt and DOC concentrations, changes in either salinity or DOC concentration can impact the photodegradation rates of MMHg.

There is an increasing number of randomized clinical trials intended to assess the effectiveness of indoor air cleaners for improving participant outcomes in real-world settings. In this communication, we synthesize the current state of registered air cleaner intervention trials and call attention to the critical importance of conducting measurements to characterize the performance and in situ utilization of air cleaners in such trials to improve interpretation of exposure measurements and patient outcomes. We draw upon the existing literature and preliminary findings from our ongoing one-year, randomized, single-blind, placebo-controlled case-control trial of stand-alone air filtration in the homes of U.S. military Veterans to inform our recommendations. We demonstrate how to conduct industry-standard performance testing and how to use long-term measurements of air cleaner power draw to assess air cleaner operation. In our analysis of interim data from 53 homes to date with a mean data collection period of 275 days, we found that most air cleaners, whether active or sham, were operated predominantly at low or medium fan speeds, and most participants operated their air cleaner on predominantly one fan speed. In a few homes, air cleaners were mostly off. We estimate that air cleaner operation in these homes is providing a median additional equivalent particle loss rate of ∼0.7/h (ranging ∼0-2.8/h). Accordingly, we recommend that air cleaner intervention trials adopt the steps described herein to account for the amount of clean air delivered in real-world settings and to provide important context alongside indoor exposure measurements and analysis of patient outcomes.

Hearing loss (HL) is an otolaryngology disease susceptible to environmental pollutants. Volatile organic compounds (VOCs), as a class of chemical pollutants with evaporation propensity, pose a great threat to human health. However, the association between VOCs and HL remains unclear. This study aimed to explore the association between urinary-specific VOC metabolites and HL. It included 1048 participants from the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2012. Multivariate linear regression models, smooth curve analysis, and stratified analysis were employed to investigate the relationship between urinary-specific VOC metabolite concentrations and pure tone audiometry (PTA) across three different frequencies. A two-piecewise linear regression model was employed to analyze the threshold effects of urinary-specific VOC metabolites on hearing threshold changes. Furthermore, a comparative toxicogenomics database (CTD) and functional gene enrichment were constructed. An interaction network of transcription factors, genes, and non-coding RNA was constructed to further confirm the upstream and downstream regulatory relationships. Molecular docking analyses were conducted to explore the potential binding modes and critical docking sites. Additionally, a moderation analysis was conducted to investigate the role of oxidative stress in moderating the influence of VOC metabolites on hearing. Multivariate linear regression model discerned a significant correlation between cyanide 2-aminothiazoline-4-carboxylic acid (ATCA) with speech-frequency PTA and N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA) with high-frequency PTA. The smoothed curve and threshold effect analysis corroborated a positive linear relationship between cyanide ATCA and speech-frequency PTA without a threshold effect only in the 20–34 age group. Additionally, the bioinformatics analysis discovered pathogenic genes related to cyanide-induced HL and suggested that oxidative stress responses play a critical role in this biological process. Furthermore, the moderation effect of total bilirubin (TB), an oxidative stress-associated molecule, was ascertained on the effects of ATCA on hearing. Our findings suggest a potential link between VOC metabolites and hearing and indicate the crucial role of oxidative stress responses in this association.

Oil leakage into soil is a major environmental concern, affecting its physical, chemical, biological, and geotechnical properties, which threatens soil fertility. Remediating contaminated sites helps mitigate risks to human health, the environment, and the economy, while also enabling land reuse for development or agriculture. Petroleum spills generally occur during production, processing, transportation, and storage. This review discusses the impact of hydrocarbon contamination on soil and its surrounding environment and examines various remediation techniques, including physical–chemical methods (soil excavation, soil washing, soil vapor extraction, thermal treatment, and chemical oxidation), biological methods (bioremediation and phytoremediation), nanotechnology-based approaches, and integrated methods. The effectiveness, limitations, and applicability of these techniques are critically analyzed, providing a comprehensive framework for managing soil contamination by petroleum hydrocarbons.

Background: Exposure to particulate matter <2.5 μm (PM_2.5) is linked to chronic obstructive pulmonary disease (COPD), but most studies lack individual PM_2.5 measurements. Seasonal variation and their impact on clinical outcomes remain understudied. Objective: This study investigated the impact of PM_2.5 concentrations on COPD-related clinical outcomes and their seasonal changes. Methods: A multicentre panel study enrolled 105 COPD patients (age range: 46-82) from July 2019 to August 2020. Their mean forced expiratory volume in 1 second after bronchodilation was 53.9%. Individual PM_2.5 levels were monitored continuously with indoor measurements at residences and outdoor data from the National Ambient Air Quality Monitoring Information System. Clinical parameters, including pulmonary function tests, symptom questionnaires (CAT and SGRQ-C), and impulse oscillometry (IOS), were assessed every three months over the course of one year. Statistical analysis was conducted using a linear mixed-effect model to account for repeated measurements and control for confounding variables, including age, sex, smoking status and socioeconomic status. Results: The mean indoor and outdoor PM_2.5 concentrations were 16.2 ± 8.4 μg m^-3 and 17.2 ± 5.0 μg m^-3, respectively. Winter had the highest PM_2.5 concentrations (indoor, 18.8 ± 11.7 μg m³; outdoor, 22.5 ± 5.0 μg m^-3). Higher PM_2.5 concentrations significantly correlated with poorer St. George's Respiratory Questionnaire for COPD (SGRQ-C) scores and increased acute exacerbations, particularly in winter. Patients of lower socioeconomic status were more vulnerable. Increased PM_2.5 concentrations were also associated with amplified small airway resistance (R5-R20). Conclusions: PM_2.5 concentration changes are positively correlated with poorer SGRQ-C scores and increased acute exacerbations in COPD patients with significant seasonal variations, especially in winter.

Continuous consumption combined with incomplete removal during wastewater treatment means residues of psychotropic drugs (PDs), including antidepressants, antipsychotics, antiepileptics and illicit drugs, are continuously entering the aquatic environment, where they have the potential to affect non-target organisms. Photochemical transformation is an important aspect to consider when evaluating the environmental persistence of PDs, particularly for those present in sunlit surface waters. This review summarizes the latest research on the photodegradation of typical PDs under environmentally relevant conditions. According to the analysis results, four classes of PDs discussed in this paper are influenced by direct and indirect photolysis. Indirect photodegradation has been more extensively studied for antidepressants and antiepileptics compared to antipsychotics and illicit drugs. Particularly, the photosensitization process of dissolved organic materials (DOM) in natural waters has received significant research attention due to its ubiquity and specificity. The direct photolysis pathway plays a less significant role, but it is still relevant for most PDs discussed in this paper. The photodegradation rates and pathways of PDs are influenced by various water constituents and parameters such as DOM, nitrate and pH value. The contradictory results reported in some studies can be attributed to differences in experimental conditions. Based on this analysis of the existing literature, the review also identifies several key aspects that warrant further research on PD photodegradation. These results and recommendations contribute to a better understanding of the environmental role of water matrixes and provide important new insights into the photochemical fate of PDs in aquatic environments.

Alum shale formations in Scandinavia are generally enriched in uranium (U) and, when exposed to air and water, may produce acidic rock drainage (ARD), releasing potentially harmful elements into the environment. Taraldrud is a legacy site in southeast Norway where approx. 51 000 m³ of alum shale was deposited in the 1980s–1990s. In 2006, ARD formation became obvious after high concentrations of leachable elements and low environmental pH were measured in a nearby stream. A manmade precipitation pond and liming treatments attempt to address the environmental pollution, but the site remains non-remediated. This study aimed to evaluate the extent of contamination caused by ARD and examine environmental and human health risks caused by mobilized trace elements and radionuclides. Surface water, sediment, soil, and biota samples were collected in the area and chemically and/or radiochemically analyzed to assess the prevailing concentrations within different environmental compartments. The elemental distribution and variation patterns were studied using principal component analysis. Most of the leachable elements were present in highly mobile and bioavailable forms in the pond water, out of which Cd, Mn, Ni, and U exceeded drinking water regulations. The highest enrichment in soil and sediment was for U, which was associated with the sulfide-bearing soil fraction, Fe, Cu, Mo, and As. No changes in water quality were observed between up- and downstream from the site, indicating that the Fe and S rich phases in the pond retain the leachable elements effectively under prevailing environmental conditions. This study provides valuable insights into the risks and challenges associated with ARD and where U is the main pollutant of concern.

The increasing global demand for plastic has raised the need for effective waste plastic management due to its long lifetime and resistance to environmental degradation. There is a need for rapid plastic identification to improve the mechanical waste plastic sorting process. This study presents a novel application of Temperature-Programmed Desorption-Direct Analysis in Real Time-High Resolution Mass Spectrometry (TPD-DART-HRMS) that enables rapid characterization of various plastics. This technique was applied on four commercially available reference polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride) as well as three “waste” plastic samples of mixed origin. These waste plastic samples were obtained as discards from various industrial processes with limited analytical characterization data. Through the application of CH₂ Kendrick mass defect (KMD) grouping, characteristic trends in the mass spectra of each sample were identified, allowing for a simplified numerical comparison. This approach utilized a robust statistical approach using the Tanimoto coefficient, allowing for the quantitative measures of similarity between standards and unknown samples. The application of this mathematical evaluation methodology was used to identify plastic types and to distinguish structurally similar polymers. Additionally, we report that a chloride ion clustering effect with copper substrate can identify chlorinated polymer PVC (polyvinyl chloride) utilizing pyro-(−)DART-HRMS mode. PVC polymer is of particular interest in recycling due to its high chloride content, which can present technical challenges for some types of recycling. We found that chloride ion clusters are a good screening marker for the presence of chlorinated polymers in mixed waste plastic samples. This study can possibly help advance rapid and accurate analytical techniques for identifying the composition of waste plastics to advance the effectiveness of the waste plastic sorting process.

Conventional practices for inorganic nitrogen fertilizer are highly inefficient leading to excess nitrogen in the environment. Excess environmental nitrogen induces ecological (e.g., hypoxia, eutrophication) and public health (e.g., nitrate contaminated drinking water) consequences, motivating adoption of management strategies to improve fertilizer use efficiency. Yet, how to limit the environmental impacts from inorganic nitrogen fertilizer while maintaining crop yields is a persistent challenge. The lack of empirical data on the fate and transport of nitrogen in an agriculture soil-crop system and how transport changes under varying conditions limits our ability to address this challenge. To this end, we developed a mechanistic model to assess how various parameters within a soil-crop system affect where nitrogen goes and inform how we can perturb the system to improve crop nitrogen content while reducing nitrogen emissions to the environment. The model evaluates nitrogen transport and distribution in the soil-corn plant system on a conventional Iowa corn farm. Simulations determine the amount of applied nitrogen fertilizer acquired by the crop root system, leached to groundwater, lost to tile drainage, and denitrified. Through scenario modeling, it was found that reducing application rates from 200 kg ha⁻¹ to 160 kg ha⁻¹ had limited impact on plant nitrogen content, while decreasing wasted nitrogen fertilizer by 25%. Delayed application until June significantly increased the f-NUE and denitrification while reducing the amount of fertilizer leached and exported through tile drainage. The value in a model like the one presented herein, is the ability to perturb the system through manipulation of variables representative of a specific scenario of interest to inform how one can improve crop-based nitrogen management.

The high salinity and organic content in oil and gas wastewaters can cause ion suppression during liquid chromatography mass spectrometry (LC/MS) analysis, diminishing the sensitivity and accuracy of measurements in available methods. This suppression is severe for low molecular weight organic compounds such as ethanolamines (e.g., monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), N-methyldiethanolamine (MDEA), and N,N-ethyldiethanolamine (EDEA)). Here, we deployed solid phase extraction (SPE), mixed-mode LC, triple quadrupole MS with positive electrospray ionization (ESI), and a suite of stable isotope standards (i.e., one per target compound) to correct for ion suppression by salts and organic matter, SPE losses, and instrument variability. The method was evaluated in produced water samples from Italy (NaCl salinity from 8110–18 100 mg L⁻¹; diesel range organic compounds ranging from 5.1–7.9 mg L⁻¹). After correcting for matrix effects, ethanolamines in produced water samples were quantified. The first batch of samples (March 2019) had 37–646 μg L⁻¹ total ethanolamines. The second batch of samples (September 2019) had greater ethanolamine content of 77–3976 μg L⁻¹ which was attributed to a reduced water cut during oil production, enhancing the proportionate abundance of these compounds in the aqueous phase. In all samples, DEA and MEA were the dominant ethanolamine species. Possible sources (e.g., corrosion inhibitor and biotransformation) and natural attenuation potential during storage (e.g., at different temperatures, acidification, and addition of sodium azide) were investigated. The developed analytical method enables further investigation of the fate of low molecular weight organic additives in oil and gas development and provides an enhanced ability to evaluate risks associated with chemical release to the environment.