Browsing by Author "He, Ke"
Now showing 1 - 9 of 9
Results Per Page
Sort Options
Item 17β-Estradiol (E2) may be involved in the mode of crustacean female sex hormone (CFSH) action in the blue crab, Callinectes sapidus(Frontiers, 2022-07-25) Wang, Tao; He, Ke; Blaney, Lee; Chung, J. Sook17β-estradiol (E2) has been proved to control reproduction, sexual differentiation, and the development of the secondary sexual characteristics of vertebrate females. In decapod crustacean species, crustacean female sex hormone (CFSH), a protein hormone, is required for developing adult-specific ovigerous setae for embryo brooding and gonophores for mating at the blue crab Callinectes sapidus puberty molting. However, it is unclear that whether the mode of CFSH action involves a vertebrate-type sex steroid hormone in crustaceans. To this end, E2 levels were first measured using a competitive ELISA in the hemolymph and the potential CFSH target tissues from both prepuberty and adult females; the presence of E2 was further confirmed with a liquid chromatography tandem mass spectrometry method. Then, the cDNAs of the following genes known to be associated with vertebrate steroidogenic pathways were isolated: StAR-related lipid transfer protein 3 (StAR3); 3β-hydroxysteroid dehydrogenase (3βHSD); two isoforms of 17β-hydroxysteroid dehydrogenase 8 (17βHSD8); and, estradiol-related receptor (ERR). RT-PCR analysis revealed that these genes were widely distributed in the eyestalk ganglia, hepatopancreas, brain, ovary, spermathecae, ovigerous and plumose setae tissues of adult females. The 17βHSD8 transcripts were localized in the follicle cells, the periphery of the nuclear membrane of primary oocytes, and yolk granules of the vitellogenic oocytes using in situ hybridization, and the corresponding protein was detected in the follicle cells and ooplasm of primary oocytes using immunohistochemistry. Furthermore, the adult females injected with CFSH-dsRNA (n = 30 times) had E2 and StAR3 transcripts levels lower in the ovigerous and plumose setae, spermathecae than controls. These results suggested that the mode of CFSH action in C. sapidus might involve E2 in these adult-female-specific tissues.Item Advanced Liquid Chromatography with Tandem Mass Spectrometry Method for Quantifying Glyphosate, Glufosinate, and Aminomethylphosphonic Acid Using Pre-Column Derivatization(ACS, 2023-05-24) Martin, Pedro J.; He, Ke; Blaney, Lee; Hobbs, Shakira R.Analytical limitations make it challenging to develop effective methodologies for understanding glyphosate-based herbicide levels in drinking water and groundwater. Due to their lack of chromophores and zwitterionic nature, glyphosate-based herbicides are difficult to detect using traditional methods. This paper offers a straightforward method for quantifying glyphosate, glufosinate, and aminomethylphosphonic acid (AMPA) via 9-fluorenylmethylchloroformate (FMOC-Cl) pre-column derivatization and analysis by liquid chromatography with tandem mass spectrometry (LC–MS/MS). Method development was focused on optimizing the critical variables for optimal derivatization using a 24-factorial design. We found that complete derivatization significantly depends on the inclusion of borate buffer to create the alkaline conditions necessary for aminolysis. Ethylenediaminetetraacetic acid (EDTA) addition was critical to minimize metallic chelation and ensure reproducible retention times and peaks. However, EDTA concentrations ≥5% decreased peak intensity due to ion suppression. The FMOC-Cl concentration and derivatization time exhibited a direct proportional relationship, with the complete reaction achieved with 2.5 mM FMOC-Cl after 4 h. Concentrations of FMOC-Cl greater than 2.5 mM led to the formation of oxides, which interfere with the detection sensitivity and selectivity. Desirable results were achieved with 1% EDTA, 5% borate, and 2.5 mM FMOC-Cl, which led to complete derivatization after 4 h.Item Bioaccumulation of estrogenic hormones and UV-filters in red swamp crayfish (Procambarus clarkii)(Elsevier, 2020-10-10) He, Ke; Hain, Ethan; Timm, Anne; Blaney, LeeEstrogenic hormones and organic ultraviolet-filters (UV-filters) have attracted increased attention as endocrine disrupting chemicals (EDCs) due to their potent estrogenicity and widespread occurrence in the environment. This study investigated the accumulation of three estrogenic hormones and five UV-filters in red swamp crayfish (Procambarus clarkii). Exposure experiments were conducted for 42 days with a mixture of EDCs at two environmentally-relevant design concentrations (i.e., 500 and 5000 ng L−1). The aqueous-phase EDC concentrations decreased over time and were re-established every two days. Within 14 days of exposure, the five UV-filters were measured at 2.2 to 265 ng g−1 (dry weight) in crayfish tail tissue. Only one estrogenic hormone, 17β-estradiol, was detected in the crayfish at 10.4–13.5 ng g−1. No apparent changes were observed for EDC concentrations in the tail tissue over the next four weeks of exposure. The apparent bioaccumulation factors for the EDCs ranged from 23 L (kg tail tissue, dry weight)−1 for 4-methylbenzylidene camphor to 1050 L (kg tail tissue, dry weight)−1 for 2-ethylhexyl-4-methoxycinnamate. EDC input was stopped after 42 days, and the more hydrophobic UV-filters (i.e., octocrylene, 2-ethylhexyl-4-methoxycinnamate, homosalate) were found to be persistent throughout a 14-d elimination period. A lyticase-assisted yeast estrogen screen demonstrated that the residual estrogenic activity of water samples aligned with (or was lower than) predictions from targeted chemical analysis. These results suggest that the transformation products did not contribute significant estrogenicity, although further analysis of endocrine disruption outcomes in crayfish is recommended.Item Effects of antimicrobial exposure on detrital biofilm metabolism in urban and rural stream environments(Elsevier B.V., 2019-05-20) Jepsen, Rikke; He, Ke; Blaney, Lee; Swan, ChristopherThe occurrence of antimicrobials and other pharmaceuticals in streams is increasingly being reported, yet the impacts of these contaminants of emerging concern on aquatic ecosystems are relatively unknown. Bacteria and fungi are vital components of stream environments and, therefore, exposure to antimicrobials may have important consequences for ecosystem services, such as carbon cycling. The objective of this study was to investigate how two antimicrobials, ciprofloxacin and climbazole, impact detrital biofilm metabolism in urban and rural streams. To establish baseline conditions, the biological oxygen demand (BOD) of red maple (Acer rubrum) biofilms was measured in one urban and one rural stream. In mesocosm studies, the BOD of biofilms on singleand mixed-species leaf litter from the same sites was measured after exposure to 10 μg/L of the antimicrobials, both in combination and individually. The presence of ciprofloxacin and climbazole did not affect BOD compared to the controls at the urban site, although significant differences were identified for select treatments at the rural site. In addition, the BOD of mixed-leaf biofilms was not significantly different from that of single species litter after exposure. Overall, exposure to 10 μg/L of the antimicrobials did not significantly impact community-level carbon processing by the leaf biofilms, and leaf mixtures did not result in increased biofilm BOD compared to single species leaves. The outcomes of this work demonstrate a need for further research for the understanding the effects of antimicrobials on rural streams to prevent unintended consequences to ecological processes and biota from future development, leaking septic systems, and wastewater spills.Item Geospatial and co-occurrence analysis of antibiotics, hormones, and UV filters in the Chesapeake Bay (USA) to confirm inputs from wastewater treatment plants, septic systems, and animal feeding operations(Elsevier, 2023-10-15) Hain, Ethan; He, Ke; Batista-Andrade, Jahir A.; Feerick, Anna; Tarnowski, Mitchell; Timm, Anne; Blaney, LeePrevious studies have reported select contaminants of emerging concern (CECs) in limited areas of the Chesapeake Bay (USA), but no comprehensive efforts have been conducted. In this work, 43 antibiotics, 9 hormones, 11 UV filters, and sucralose, were measured in matched water, sediment, and oyster samples from 58 sites. The highest sucralose concentration was 3051 ng L⁻¹ in a subwatershed with 4.43 million liters of wastewater effluent per day (MLD) and 4385 septic systems. Although antibiotic occurrence was generally low in subwatersheds located in less populated areas, 102 ng L⁻¹ ciprofloxacin was detected downstream of 0.58 MLD wastewater effluent and 10 animal feeding operations. Hormones were not regularly detected in water (2%) or oysters (37%), but the high detection frequencies in sediment (74%) were associated with septic systems. UV filters were ubiquitously detected in oysters, and octisalate exhibited the highest concentration (423 ng g⁻¹). Oyster-phase oxybenzone and aqueous-phase sucralose concentrations were significantly correlated to wastewater effluent and septic systems, respectively. Toxicity outcomes were predicted for homosalate and octisalate throughout the Bay, and antimicrobial resistance concerns were noted for the Chester River. The geospatial and co-occurrence relationships constitute crucial advances to understanding CEC occurrence in the Chesapeake Bay and elsewhere.Item Ion Exchange Membranes and Fibers as Passive Samplers for Chemically-diverse PFAS: ESTCP Project ER20-1073(2021-12-31) Blaney, Lee; He, KeProject Number: ER20-1073 Project Title: Ion exchange membranes and fibers as passive samplers for chemically-diverse PFAS Lead Principal Investigator: Lee Blaney, PhD Lead Organization: University of Maryland Baltimore County (UMBC) Objective: The overall goal of this project was to develop ion-exchange membrane and fiber strategies for passive sampling of chemically diverse PFAS. The project was developed to address DoD’s needs with respect to measurement and remediation of PFAS. The specific objectives were as follows: (1) develop ion-exchange membrane and fiber passive samplers capable of concentrating short- and longchain PFAS with varying log D values; (2) establish selectivity coefficients for 19 PFAS of concern in the ion exchange-based samplers to quantitatively describe PFAS uptake and partitioning; (3) confirm that the ion-exchange materials are capable of effective deployment and performance in synthetic and real groundwater and surface water matrices; (4) investigate ion exchange-based passive samplers for cationic, zwitterionic, and anionic PFAS; (5) ensure consistent performance of the samplers in single- and multisorbate scenarios; (6) characterize effects of solution pH, ionic strength, background ions, temperature, and dissolved organic matter on the passive samplers; and, (7) deploy the passive samplers in laboratorybased mesocosms to confirm their ability to resolve spatiotemporal variations in PFAS concentration. Technical Approach: Ion-exchange membranes and fibers represent a paradigm shift in passive sampling strategies for organic contaminants and PFAS, in particular. This shift stems from the wideranging physicochemical properties of PFAS, which complicate traditional passive sampling strategies. The specific objectives were achieved through (i) batch sorption tests to identify selectivity coefficients, competitive effects, and impacts of interfering substances on PFAS uptake by the sampler and (ii) mesocosm studies using synthetic and real water matrices. The limited-scope portion of the project was focused on Objectives 1, 2, and 3. Results: Our findings indicated that PFAS uptake into the ion-exchange membranes was fairly rapid, namely 2-3 days under well-mixed conditions and 2-4 weeks under static conditions; furthermore, these results were confirmed in large-volume studies using a real groundwater and pond water. We confirmed through both sorption and desorption studies that ion exchange was the primary mechanism of uptake for short- and long-chain PFAS with different head groups. The uptake capacity, selectivity coefficients, and PFAS recovery (extraction) were measured for ten ion-exchange membranes and one set of ion-exchange fibers. Based on the aggregate results, the FAD-PET-75 membrane was selected as the optimal choice for follow-on work. The selectivity coefficients for PFAS over chloride ranged from 1.57 (PFBA) to 4.90 (PFOS), and 1-4 cm2 membrane coupons were able to accumulate enough PFAS for downstream analysis. The selectivity coefficients demonstrated trends with chain-length and head group. The total dissolved solids concentration (related to ionic strength) in real groundwater and pond water affected the observed selectivity coefficients, which increased with salt content, but these parameters were successfully corrected using Setschenow constants. The FAD-PET-75 membrane was effectively dissolved in methanol to achieve high recovery of short- and long-chain PFAS (e.g., 87% PFBA, 104% PFOA). We also developed prototype samplers that will continue to be refined for field deployments in the proposed follow-on work. Benefits: Given the increased importance of PFAS to ongoing cleanup and remediation efforts at DoD facilities, new strategies are required to enable monitoring of PFAS. The limit-scope portion of this project provided proof-of-concept evidence for ion exchange-based strategies, and follow-on work will continue to develop, evaluate, and test innovative ion exchange-based materials for passive sampling of PFAS. Due to the ion-exchange mechanism, the passive samplers offer robust solutions for the full range of PFAS of interest. The results of this project contributed new scientific understanding to the use of ionexchange passive samplers, which may also be useful for other DoD-relevant contaminants.Item Occurrence of antibiotics, estrogenic hormones, and UV-filters in water, sediment, and oyster tissue from the Chesapeake Bay(Elsevier, 2018-10-03) He, Ke; Hain, Ethan; Timm, Anne; Tarnowski, Mitchell; Blaney, LeeGlobally, the occurrence of contaminants of emerging concern (CECs) in the environment has raised critical questions on ecological and human health, but few efforts have focused on the Chesapeake Bay, the largest estuary in the United States. Here, 43 antibiotics, 3 estrogenic hormones, and 5 ultraviolet-filters (UV-filters), which are active ingredients in a variety of personal care products, were measured in water, sediment, and oyster tissue from 14 sites along the Eastern Shore of the Chesapeake Bay in Maryland. Fluoroquinolone, macrolide, and sulfonamide antibiotics were detected in water samples. As both human- and animal-labeled antibiotics were found, wastewater effluent and agricultural runoff were identified as potential sources. The highest aqueous-phase concentrations were recorded for norfloxacin (94.1 ng/L), enrofloxacin (17.8 ng/L), sulfamethoxazole (14.8 ng/L), and clarithromycin (9.7 ng/L). Estrone and four UV-filters, namely 2-ethylhexyl-4-methoxycinnamate, benzophenone-3, homosalate, and octocrylene, were frequently detected in Chesapeake Bay water (93–100%), sediment (100%), and oyster tissue (79–100%). High sediment-phase concentrations of estrone (58.4 ng/g) and 17β-estradiol (11.5 ng/g) were detected at the mouth of the Manokin River. Homosalate and benzophenone-3 were present at concentrations as high as 187.9 and 113.7 ng/L in water, 74.2 and 10.8 ng/g in sediment, and 158.3 and 118.0 ng/g in oyster tissue, respectively. These results demonstrate the ubiquitous presence of CECs in the Chesapeake Bay, confirm UV-filter bioaccumulation in oysters, and suggest the need for improved CEC removal during municipal wastewater treatment and agricultural waste management within the Chesapeake Bay watershed.Item Photocatalytic degradation of GenX in water using a new adsorptive photocatalyst(Elsevier, 2022-07-15) Zhu, Yangmo; Ji, Haodong; He, Ke; Blaney, Lee; Xu, Tianyuan; Zhao, DongyeGenX, the ammonium salt of hexafluoropropylene oxide dimer acid, has been used as a replacement for perfluorooctanoic acid. Due to its widespread uses, GenX has been detected in waters around the world amid growing concerns about its persistence and adverse health effects. As relevant regulations are rapidly evolving, new technologies are needed to cost-effectively remove and degrade GenX. In this study, we developed an adsorptive photocatalyst by depositing a small amount (3 wt.%) of bismuth (Bi) onto activated-carbon supported titanate nanotubes, Bi/TNTs@AC, and tested the material for adsorption and subsequent solid-phase photodegradation of GenX. Bi/TNTs@AC at 1 g/L was able to adsorb GenX (100 µg/L, pH 7.0) within 1 h, and then degrade 70.0% and mineralize 42.7% of pre-sorbed GenX under UV (254 nm) in 4 h. The efficient degradation also regenerated the material, allowing for repeated uses without chemical regeneration. Material characterizations revealed that the active components of Bi/TNTs@AC included activated carbon, anatase, and Bi nanoparticles with a metallic Bi core and an amorphous Bi₂O₃ shell. Electron paramagnetic resonance spin-trapping, UV-vis diffuse reflectance spectrometry, and photoluminescence analyses indicated the superior photoactivity of Bi/TNTs@AC was attributed to enhanced light harvesting and generation of charge carriers due to the UV-induced surface plasmon resonance effect, which was enabled by the metallic Bi nanoparticles. •OH radicals and photogenerated holes (h⁺) were responsible for degradation of GenX. Based on the analysis of degradation byproducts and density functional theory calculations, photocatalytic degradation of GenX started with cleavage of the carboxyl group and/or ether group by •OH, h⁺, and/or eₐq⁻, and the resulting intermediates were transformed into shorter-chain fluorochemicals following the stepwise defluorination mechanism. Bi/TNTs@AC holds the potential for more cost-effective degradation of GenX and other per- and polyfluorinated alkyl substances.Item Retention of per- and polyfluoroalkyl substances by syringe filters(Springer, 2024-03-19) He, Ke; Feerick, Anna; Jin, Hongyue; Batista-Andrade, Jahir Antonio; Duarte Batista, Marylia; Dugan, Caitlyn; Blaney, LeePer- and polyfluoroalkyl substances (PFAS) are being increasingly measured in water and wastewater due to emerging toxicity concerns and strict regulatory limits. Previous studies have filtered water samples to remove suspended solids before PFAS analysis. However, filtration may introduce negative bias to measured PFAS concentrations. Using a well-controlled syringe pump assembly, we evaluated retention of six perfluoroalkyl carboxylates, three perfluoroalkyl sulfonates, one fluorotelomer sulfonate, and two perfluorooctane sulfonamides by glass-fiber, glass-fiber cellulose acetate, nylon, polyethersulfone, polypropylene, polyvinylidene fluoride/ difluoride, and surfactant-free cellulose acetate filters. The impacts of water quality and operational parameters were also investigated for select filter types. We found that PFAS were retained on all filters, with the glass-fiber cellulose acetate filters demonstrating the lowest retention. For all filters, PFAS retention was linearly related to chain length and hydrophobicity above certain thresholds (i.e., log D higher than 1.5). Importantly, more PFAS were retained at low filtrate volumes, and ~30 mL filtrate was required before the retention efficiencies stabilized. Solution pH only affected the retention of perfluorooctane sulfonamides. Pore size (i.e., 0.20, 0.45, 0.70 µm), filtration rate (i.e., 0.5, 1.0 mL min⁻¹), and PFAS concentration (i.e., 10, 100 µg L⁻¹), did not exert major influences on PFAS retention. The presence of dissolved organic matter improved PFAS permeation. Based on the reported results, filtration introduces bias and is not recommended for sample pretreatment.