Publications by authors named "Alex Chow"

Triplet-state dissolved organic matter (DOM*) plays a crucial role in environmental aquatic photochemistry, with 2,4,6-trimethylphenol (TMP) frequently used as a chemical probe or quencher due to its high reactivity with DOM*. However, the influence of TMP-derived oxidation intermediates on the target photochemical reactions has not been comprehensively examined. This study investigated TMP's effect on the photolysis of sulfamethoxazole (SMX), a common antibiotic found in natural waters, in the presence of different DOM sources or model photosensitizer.

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  • Seasonal algal blooms pose a risk to drinking water quality, and oxidative treatment can effectively remove algal cells but releases algal organic matter (AOM) that can complicate water treatment.
  • Different oxidants (like chlorine and ozone) impact the molecular characteristics of AOM, with ozone causing the most significant changes in its composition.
  • The study highlights that while oxidative treatment can reduce harmful reactions during water disinfection, it may also lead to the formation of new byproducts, including some that could be more concerning for water safety.
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  • Climate change is leading to more frequent and intense wildfires, particularly in areas experiencing prolonged summer droughts.
  • This study focused on how mercury (Hg) is transported in water from recently burned and unburned watersheds in northern California, analyzing its forms during storm events and normal flow.
  • Findings indicate that the aftermath of wildfires causes a temporary spike in suspended solids and mercury levels, linked primarily to ash deposits, but these levels decrease significantly with the rapid regrowth of vegetation over time.
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  • The adsorption process is a cost-effective method for removing PFAS from irrigation water, but syringe filtration can lead to PFAS retention, skewing results.
  • In a study, three common PFAS were tested for recovery on different syringe filters, revealing varying recovery rates, with MCE filters showing the best performance.
  • Results indicated that PFAS recovery improved with increased filtration volume, emphasizing the importance of filter choice in accurately measuring the effectiveness of PFAS removal in lab settings.
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The use of reclaimed water from wastewater treatment plants for irrigation has a risk of introducing micropollutants such as microplastics (MPs) and antimicrobials (AMs) into the agroecosystem. This study was conducted to investigate the effects of single and combined treatment of 0.1 % polyamide (PA ∼15 μm), and varying sulfamethoxazole (SMX) levels 0, 10, 50, and 150 mg/L on rice seedlings (Oryza sativa L.

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  • Liver abscesses are rare infections typically caused by enteric gram-negative bacteria, requiring antibiotic treatment and sometimes drainage.
  • A 37-year-old man with ongoing abdominal pain was diagnosed with a large pyogenic liver abscess that extended into his chest wall, caused by an unusual pathogen.
  • The case highlights the difficulty of diagnosing rare pathogens in liver abscesses and shows that surgical drainage can be essential when initial drainage efforts fail.
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The rapid development of the economy has led to an increase in the sulfur and nitrogen load in surface water, which has the potential to cause river eutrophication and the emission of malodorous gases. A lab-scale sediment microbial fuel cell coupled with Vallisneria natans (P-SMFC) was designed for surface water remediation. The enhancement of pollutant removal performance of P-SMFC was evaluated in contrast to the SMFC system without plants (SMFC), the open-circuit control system with plants (C-P), and the open-circuit control system without plants (C-S), while illustrating the mechanisms of the sulfur and nitrogen transformation process.

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The 2018 Camp Fire was a large late-year (November) wildfire that produced an urban firestorm in the Town of Paradise, California, USA, and destroyed more than 18 000 structures. Runoff from burned wildland areas is known to contain ash, which can transport contaminants including metals into nearby watersheds. However, due to historically infrequent occurrences, the effect of wildland-urban interface (WUI) fires, such as the Camp Fire, on surface water quality has not been well-characterized.

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Unlabelled: Wetlands cover a small portion of the world, but have disproportionate influence on global carbon (C) sequestration, carbon dioxide and methane emissions, and aquatic C fluxes. However, the underlying biogeochemical processes that affect wetland C pools and fluxes are complex and dynamic, making measurements of wetland C challenging. Over decades of research, many observational, experimental, and analytical approaches have been developed to understand and quantify pools and fluxes of wetland C.

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Pollution with emerging microscopic contaminants such as microplastics (MPs) and nanoplastics (NPs) including polystyrene (PS) in aquatic and terrestrial environments is increasingly recognized. PS is largely used in packaging materials and is dumped directly into the ecosystem. PS micro-nano-plastics (MNPs) can be potentially bioaccumulated in the food chain and can cause human health concerns through food consumption.

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Wetlands are widely regarded as biogeochemical hotspots of highly toxic methylmercury (MeHg), mainly mediated by sulfate-reducing bacteria. In low-lying coastal wetlands, sea level rise, a phenomenon caused by global climate change, is slowly degrading numerous healthy freshwater forested wetlands into salt-degraded counterparts with a nickname "ghost forests", and eventually converting them to saltmarshes. However, little is known about the changes of mercury (Hg) methylation, bioaccumulation, and biomagnification along the forest-to-saltmarsh gradient.

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With the advancements in lithium-ion battery technology, lithium has been extensively used in many electronic products. Lithium usage is expected to increase in the coming decades. Elevated levels of lithium in the environments, including source water and biota, have been recently reported.

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High-intensity wildfires alter the chemical composition of organic matter, which is expected to be distinctly different from low-intensity prescribed fires. Herein, we used pyrolysis gas chromatography/mass spectrometry (Py-GC/MS), in conjunction with solid-state C nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopy, to assess chemical alterations from three wildfires and a long-term frequent prescribed fire site. Our results showed that black ash formed under moderate intensity burns contained less aromatic (ArH), polyaromatic hydrocarbon (PAH), and nitrogen-containing compounds (Ntg) but more lignin (LgC) and phenol compounds (PhC), compared to white ash formed under high intensity burns.

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Mercury (Hg) is a ubiquitous contaminant in the environment and its methylated form, methylmercury (MeHg), poses a worldwide health concern for humans and wildlife, primarily through fish consumption. Global production of forest fire ash, derived from wildfires and prescribed burns, is rapidly increasing due to a warming climate, but their interactions with aqueous and sedimentary Hg are poorly understood. Herein, we compared the differences of wildfire ash with activated carbon and biochar on the sorption of aqueous inorganic Hg and sedimentary Hg methylation.

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Article Synopsis
  • Despite improvements in analytical techniques, accurately measuring dissolved organic carbon (DOC) in environmental samples remains challenging; this review aims to explore DOC's roles in water systems, identify existing problems in DOC characterization, and suggest ways to enhance analytical accuracy.
  • The paper outlines DOC's ecological and engineering functions, highlighting its importance in nutrient cycling, pollutant fate, and water treatment, while also addressing major challenges like variability in DOC levels and unknown chemical structures.
  • The review details DOC analysis procedures, offering insights into the sampling, isolation, storage, and analytical processes, evaluating the pros and cons of various methods and providing recommendations for better accuracy throughout these stages.
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Releases of hydrogen sulphide (HS) and sulphur ions (S) through sulphate reduction in black-odorous waterbody is a great environmental health concern. Aquatic planting for blackening and odour controls has received great attention in research and practice. Nitrate concentration in black-odorous waterbody can vary significantly but little is known about the responses of aquatic plants on HS and S releases under different nitrate levels.

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Forested land plays an essential role in water supply across the United States (US). Smoldering commonly existing in wildfires contributes significantly to biomass consumption and gas emission, but its influence on source water quality has been rarely studied. Here, we investigated the impact of smoldering temperature (i.

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Considerable recent research has confirmed that anthropogenic materials including microplastics and nanomaterials have been integrated into soil and dissolved organic matter in the environment. These pools of organic matter could be geochemically processed through different pathways and have different chemical and physical characteristics than the pools of natural organic matter (NOM). However, environmental scientists and engineers currently refer to any organic matter collected in soil, water, and sediments as NOM.

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Young adults born at the end of the 20th century attend colleges and universities at much higher rates than did previous generations, which might give the impression of greater upward educational mobility and in turn, greater class mobility. This impression occurs, however, only because of structural expansion of the Canadian education system. In contrast to structural change, exchange mobility highlights the linkage between one's social origins and destinations.

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Microplastics (MPs) are widespread in natural ecosystems and have attracted considerable attention from scientists all over the world because they are believed to threaten every life form. In addition to their potential physical and chemical effects on organisms, MPs may act as a carrier for many micropollutants, including antibiotics, heavy metals, and others. Over the last 10-15 yr, extensive research has been carried out on MPs in marine environments regarding their sources, fate, and toxicity.

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Copper-based algaecides are usually used for controlling algae bloom triggered by the elevated levels of nutrients after wildfires, resulting in the promoted reactivity of dissolved organic matter (DOM) in forming disinfectant byproducts (DBPs). To identify the best strategy for handling this source water, we employed Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to characterize the DBPs precursors after 4-d Microcystis aeruginosa bloom cultured with black (BE) and white (WE) ash water extracts under 0, 0.5, and 1.

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Article Synopsis
  • This study examines how prescribed fires impact the export of dissolved organic matter (DOM) and precursors of disinfectant by-products (DBPs) from forest fuel materials, including live vegetation and debris, over different burning schedules and seasons.
  • Results show that prescribed fires significantly reduced total fuel load and dissolved organic carbon (DOC) leaching, with decreases in total dissolved nitrogen (TDN) and other nutrients by up to 70% compared to unburned materials.
  • The study also found that prescribed fires reduced the potential formation of trihalomethanes (THM) and haloacetic acids (HAA) by approximately 42%, while the effectiveness of coagulants in removing these compounds remained consistent.
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