Considering the increasing global plastic demand, there is a critical need to gain insight into environmental processes that govern plastic degradation in order to inform novel design of sustainable polymers. Current biological degradation testing standards focus on formation of CO2 (i.e., mineralization) alone as a diagnostic, ultimately limiting identification of structure-degradation relationships in a timely fashion. This work developed a sequential abiotic (i.e., photodegradation and hydrolysis) and biotic degradation test and applied it to a suite of 18 polymers, including ten lab produced, novel polyhydroxyalkanoate polyesters, and eight commercially available, bio-based (i.e., polylactic acid and poly-3-hydroxybutyrate) and fossil-derived (i.e., polystyrene, polypropylene, low density polyethylene, poly(ethylene terephthalate) and tire rubber) polymers. Biomineralization alone following standard methods (i.e., ASTM 6691-17, ISO 23977-1 2020) underestimated polymer degradation up to two-fold over 28 days. Simulated sunlight enhanced the overall polymer degradation by mobilizing dissolved organic carbon (DOC). After photoirradiation, up to 100% of released dissolved organic carbon was bioavailable for marine microbes over 14 days. Photodegradation and hydrolysis could be explained by structural drivers in the commodity polymers, and the lab-synthesized polymers illustrated a limit to total degradation beyond which no enhancements in degradation were achieved. Taken together, this workflow allows for relatively fast experimental determination of environmentally relevant stimuli to help support eventual elucidation of structure-property relationships for enhanced a priori design of degradable polymers.

Oil and gas (O&G) well integrity issues, including sustained casing pressure and casing vent flow, could cause significant environmental and climatic risks by releasing methane-containing fluids into the environment. The large number of O&G wells makes routine inspection or spatiotemporally adequate screening of well integrity issues expensive and sometimes intractable. Machine learning (ML) algorithms with the ability to predict O&G well integrity issues could help prioritize such inspections. We manually extracted well characteristics from 1223 O&G well completion reports in Bradford County, PA, appended geospatial metrics, and used them to predict well integrity issues reported by field tests. Different ML models (e.g., Random Forrest, XGBoost, and Logistic Regression) were compared, and an accuracy of 68% was achieved by comparing the predictions with unseen field test records. Important predictive features were identified by the Random Forrest model, such as the length of casings, amount of cement, and well operator. Moreover, the wells with integrity issues were geospatially clustered in our study region, which could be explained by the clusters of important physical features. Overall, the predictions would help prioritize well integrity inspection and have the potential to guide well design and well location selection for mitigating integrity issues that lead to methane emissions.

Split tube furnaces routinely used in nanotechnology laboratories to generate C-based nanomaterials rely on refractory ceramic insulation fibers, which can pose an inhalation risk to operators.

Small format plastics are defined as being less than 2 in. long in two or more dimensions and include items such as loose bottle caps, small cosmetic packaging, and toothbrushes. Current material recovery facility (MRF) infrastructure is usually not designed to recover these smaller objects which typically fall through screens in the glass separation unit operation. A cyclone separation process has been developed to separate the small-format plastics from the glass, improving the purity of the glass stream and allowing the smaller plastics to be returned to the plastic sorting stream. Utilizing density, the cyclone sends the lighter materials through a side outlet (plastics) and collects the heavier materials (glass) through the bottom, resulting in two purified outlet streams. With the current small-scale prototype, plastic separation efficiencies greater than 94% have been observed. The life-cycle assessment and technoeconomic analysis indicate that this new separation step would increase the global warming potential savings and improve the profitability of MRFs.

Anthropogenic organic carbon emissions reporting has been largely limited to subsets of chemically speciated volatile organic compounds. However, new aircraft-based measurements revealed total gas-phase organic carbon emissions that exceed oil sands industry-reported values by 1900% to over 6300%, the bulk of which was due to unaccounted-for intermediate-volatility and semivolatile organic compounds. Measured facility-wide emissions represented approximately 1% of extracted petroleum, resulting in total organic carbon emissions equivalent to that from all other sources across Canada combined. These real-world observations demonstrate total organic carbon measurements as a means of detecting unknown or underreported carbon emissions regardless of chemical features. Because reporting gaps may include hazardous, reactive, or secondary air pollutants, fully constraining the impact of anthropogenic emissions necessitates routine, comprehensive total organic carbon monitoring as an inherent check on mass closure.

Chemical degradation testing often involves monitoring the loss of a chemical or the evolution of a single diagnostic product through time. Here, we demonstrate a novel approach to tracing complex degradation networks using mass-spectrometry-based methods and open cheminformatics tools. Ester- and ether-based thermoplastic polyurethane (TPU_Ester and TPU_Ether) microplastics (350 mu m) and microplastics-derived dissolved organic carbon (MP-DOC) were photoweathered in a simulated marine environment and subsequently analyzed by liquid chromatography coupled to high-resolution mass spectrometry. We formula-annotated 1342 and 2344 unique features in the MP-DOC of TPU_Ester and TPU_Ether, respectively. From these, we extracted 199 and 568 plausible parent-transformation product pairs via matching of features (a) with complementary increasing and decreasing trends (Spearman's correlation coefficient between normalized intensity and time), (b) spectral similarities of at least three accurate mass MS2 fragments, and (c) at least 3 ppm agreement between the theoretical and measured change in m/z between the parent-transformation product formula. Molecular network analysis revealed that both chain scission and cross-linking reactions occur dynamically rather than degradation proceeding in a monotonic progression to smaller or more oxygenated structures. Network nodes with the highest degree of centrality were tentatively identified using in silico fragmentation and can be prioritized for toxicity screening or other physicochemical properties of interest. This work has important implications for chemical transformation tracking in complex mixtures and may someday enable improved elucidation of environmental transformation rules (i.e., structure-reactivity relationships) and fate modeling.

Lack of water quality data for private drinking water sources prevents robust evaluation of exposure risk for communities co-located with historically contaminated sites and ongoing industrial activity. Areas of the Appalachian region of the United States (i.e., Pennsylvania, Ohio and West Virginia) contain extensive hydraulic fracturing activity, as well as other extractive and industrial technologies, in close proximity to communities reliant on private drinking water sources, creating concern over potential groundwater contamination. In this study, we characterized volatile organic compound (VOC) occurrence at 307 private groundwater well sites within Pennsylvania, Ohio, and West Virginia. The majority (97%) of water samples contained at least one VOC, while the average number of VOCs detected at a given site was 5 ± 3. The majority of individual VOC concentrations fell below applicable U.S. Environmental Protection Agency (EPA) Maximum Contamination Levels (MCLs), except for chloroform (MCL of 80 μg L-1; n = 1 at 98 μg L-1), 1,2-dibromoethane (MCL of 0.05 μg L-1; n = 3 ranging from 0.05 to 0.35 μg L-1), and 1,2-dibromo-3-chloropropane (MCL of 0.2 μg L-1; n = 7 ranging from 0.20 to 0.58 μg L-1). To evaluate well susceptibility to VOCs from industrial activity, distance to hydraulic fracturing site was used to assess correlations with contaminant occurrences. Proximity to closest hydraulic fracturing well-site revealed no statistically significant linear relationships with either individual VOC concentrations, or frequency of VOC detections. Evaluation of other known industrial contamination sites (e.g., US EPA Superfund sites) revealed elevated levels of three VOCs (chloroform, toluene, benzene) in groundwaters within 10 km of those Superfund sites in West Virginia and Ohio, illuminating possible point source influence. Lack of correlation between VOC concentrations and proximity to specific point sources indicates complex geochemical processes governing trace VOC contamination of private drinking water sources. While individual concentrations of VOCs fell well below recommended human health levels, the low dose exposure to multiple VOCs occurring in drinking supplies for Appalachian communities was noted, highlighting the importance of groundwater well monitoring.

Self-reported distances to industrial sources have been used in epidemiology as proxies for exposure to environmental hazards and indicators of awareness and perception of sources. Unconventional oil and gas development (UOG) emits pollutants and has been associated with adverse health outcomes. We compared self-reported distance to the nearest UOG well to the geographic information system-calculated distance for 303 Pennsylvania, Ohio, and West Virginia residents using Cohen's Weighted Kappa. Agreement was low (Kappa = 0.18), and self-reports by Ohioans (39% accuracy) were more accurate than West Virginians (22%) or Pennsylvanians (13%, both p < 0.05). Of the demographic characteristics studied, only educational attainment was related to reporting accuracy; residents with 12-16 years of education were more accurate (31.3% of group) than those with <12 or >16 years (both 16.7%). Understanding differences between objective and subjective measures of UOG proximity could inform studies of perceived exposures or risks and may also be relevant to adverse health effects. IMPACT: We compared objective and self-reported measures of distance to the nearest UOG well for 303 Appalachian Basin residents. We found that residents' self-reported distance to the nearest UOG well had limited agreement with the true calculated distance category. Our results can be used to inform the collection and contextualize the use of self-reported data in communities exposed to UOGD. Self-reported metrics can be used in conjunction with objective assessments and can be informative regarding how potentially exposed populations perceive environmental exposures or risks and could provide insights into awareness of distance-related policies, such as setbacks.

Sinking marine particles drive the biological pump that naturally sequesters carbon from the atmosphere. Despite their small size, the compartmentalized nature of particles promotes intense localized metabolic activity by their bacterial colonizers. Yet the mechanisms promoting the onset of denitrification, a metabolism that arises once oxygen is limiting, remain to be established. Here we show experimentally that slow sinking aggregates composed of marine diatoms—important primary producers for global carbon export—support active denitrification even among bulk oxygenated water typically thought to exclude anaerobic metabolisms. Denitrification occurs at anoxic microsites distributed throughout a particle and within microns of a particle’s boundary, and fluorescence-reporting bacteria show nitrite can be released into the water column due to segregated dissimilatory reduction of nitrate and nitrite. Examining intact and broken diatoms as organic sources, we show slowly leaking cells promote more bacterial growth, allow particles to have lower oxygen, and generally support greater denitrification.

This chapter discusses the emerging and promising field of environmental applications of aerogels. Due to their large pore volume, specific surface area, and diverse range of tailorable solid-phase and surface chemistries, aerogel materials are interesting candidates for addressing many challenging environmental remediation objectives. Herein we review the use of silicate, non-silicate, and allophane-clay-based aerogels in several challenging environmental remediation applications including the removal of air pollutants, water remediation, oil spill reclamation, heavy metal capture, CO2 sequestration, trapping of pesticides, immobilization of nuclear waste, and capture of orbital space debris.

Blanket aerogels (i.e., Cabot™ Thermal Wrap® (TW) and Aspen™ Spaceloft® (SL)) with surfaces that have controllable wettability are promising advanced materials for oil recovery applications, where high oil uptake during deployment could be coupled with high oil release to enable reusability of recovered oil. The study presented here details the preparation of CO2-switchable aerogel surfaces through the application of switchable tertiary amidine (i.e., tributylpentanamidine (TBPA)) onto aerogel surfaces using drop casting, dip coating, and physical vapor deposition techniques. TBPA is synthesized via two step processes: (1) synthesis of N, N-dibutylpentanamide, (2) synthesis of N, N-tributylpentanamidine. The deposition of TBPA is confirmed by X-ray photoelectron spectroscopy. Our experiments revealed that surface coating of TBPA onto aerogel blankets was partially successful within limited set of process conditions (e.g., 290 ppm CO2 and 5500 ppm humidity for PVD, 106 ppm CO2 and 700 ppm humidity for drop casting and dip coating), but that the post-aerogel modification strategies yielded poor, heterogeneous reproducibility. Overall, more than 40 samples were tested for their switchability in the presence of CO2 and water vapor, respectively, and the success rate was 6.25 %, 11.7 % and 18 % for PVD, drop casting, and dip coating, respectively. The most likely reasons for unsuccessful coating onto aerogel surfaces are: (1) the heterogeneous fiber structure of the aerogel blankets, (2) poor distribution of the TBPA over the aerogel blanket surface.

Current approaches to carbon nanotube (CNT) synthesis are limited in their ability to control the placement of atoms on the surface of nanotubes. Some of this limitation stems from a lack of understanding of the chemical bond-building mechanisms at play in CNT growth. Here, we provide experimental evidence that supports an alkyne polymerization pathway in which short-chained alkynes directly incorporate into the CNT lattice during growth, partially retaining their side groups and influencing CNT morphology. Using acetylene, methyl acetylene, and vinyl acetylene as feedstock gases, unique morphological differences were observed. Interwall spacing, a highly conserved value in natural graphitic materials, varied to accommodate side groups, increasing systematically from acetylene to methyl acetylene to vinyl acetylene. Furthermore, attenuated total reflectance Fourier-transfer infrared spectroscopy (ATR-FTIR) illustrated the existence of intact methyl groups in the multiwalled CNTs derived from methyl acetylene. Finally, the nanoscale alignment of the CNTs grown in vertically aligned forests differed systematically. Methyl acetylene induced the most tortuous growth while CNTs from acetylene and vinyl-acetylene were more aligned, presumably due to the presence of polymerizable unsaturated bonds in the structure. These results demonstrate that feedstock hydrocarbons can alter the atomic-scale structure of CNTs, which in turn can affect properties on larger scales. This information could be leveraged to create more chemically and structurally complex CNT structures, enable more sustainable chemical pathways by avoiding the need for solvents and postreaction modifications, and potentially unlock experimental routes to a host of higher-order carbonaceous nanomaterials.

The production of fossil fuels, including oil, gas, and coal, retains a dominant share in US energy production and serves as a major anthropogenic source of methane, a greenhouse gas with a high warming potential. In addition to directly emitting methane into the air, fossil fuel production can release methane into groundwater, and that methane may eventually reach the atmosphere. In this study, we collected 311 water samples from an unconventional oil and gas (UOG) production region in Pennsylvania and an oil and gas (O&G) and coal production region across Ohio and West Virginia. Methane concentration was negatively correlated to distance to the nearest O&G well in the second region, but such a correlation was shown to be driven by topography as a confounding variable. Furthermore, sulfate concentration was negatively correlated with methane concentration and with distance to coal mining in the second region, and these correlations were robust even when considering topography. We hypothesized that coal mining enriched sulfate in groundwater, which in turn inhibited methanogenesis and enhanced microbial methane oxidation. Thus, this study highlights the complex interplay of multiple factors in shaping groundwater methane concentrations, including biogeochemical conversion, topography, and conventional fossil extraction.

Sunlight exposure can naturally mitigate microplastics pollution in the surface ocean, however it results in emissions of dissolved organic carbon (DOC) whose characteristics and fate remain largely unknown. In this work, we investigated the effects of solar radiation on polyether (TPU_Ether) and polyester (TPU_Ester) thermoplastic polyurethane, and on a thermoset polyurethane (PU_Hardened). The microplastics were irradiated with simulated solar light with a UV dose of 350 MJ m-2, which corresponds to roughly 15 months outdoor exposure at 31° N latitude. The particles were characterized using ATR-FTIR and elemental analysis. The DOC released to the aqueous phase was quantified by total organic carbon analysis and characterized by nontarget liquid chromatography coupled to high-resolution mass spectrometry. Polyurethane microplastics were degraded following mechanisms reconcilable with UV photo-oxidation. The carbon mass fraction released to the aqueous phase was 8.5 ± 0.5%, 3.7 ± 0.2%, and 2.8 ± 0.2% for TPU_Ether, TPU_Ester, and PU_Hardened, respectively. The corresponding DOC release rates, expressed as mg carbon per UV dose were 0.023, 0.013, and 0.010 mg MJ-1 for TPU_Ether, TPU_Ester and PU_Hardened, respectively. Roughly three thousand unique by-products were released from photo-weathered TPUs, whereas 540 were detected in the DOC of PU_Hardened. This carbon pool was highly complex and dynamic in terms of physicochemical properties and susceptibility to further photodegradation after dissolution from the particles. Our results show that plastics photodegradation in the ocean requires chemical assessment of the DOC emissions in addition to the analysis of aged microplastics and that polymer chemistry influences the chain scission products.

Background: Chemicals used or emitted by unconventional oil and gas development (UOGD) include reproductive/developmental toxicants. Associations between UOGD and certain birth defects were reported in a few studies, with none conducted in Ohio, which experienced a thirty-fold increase in natural gas production between 2010 and 2020.Methods: We conducted a registry-based cohort study of 965,236 live births in Ohio from 2010 to 2017. Birth defects were identified in 4653 individuals using state birth records and a state surveillance system. We assigned UOGD exposure based on maternal residential proximity at birth to active UOG wells and a metric specific to the drinking-water exposure pathway that identified UOG wells hydrologically connected to a residence ("upgradient UOG wells"). We estimated odds ratios (ORs) and 95% confidence intervals (CIs) for all structural birth defects combined and specific birth defect types using binary exposure metrics (presence/absence of any UOG well and presence/absence of an upgradient UOG well within 10 km), adjusting for confounders. Additionally, we conducted analyses stratified by urbanicity, infant sex, and social vulnerability.Results: The odds of any structural defect were 1.13 times higher in children born to mothers living within 10 km of UOGD than those born to unexposed mothers (95%CI: 0.98-1.30). Odds were elevated for neural tube defects (OR: 1.57, 95%CI: 1.12-2.19), limb reduction defects (OR: 1.99, 95%CI: 1.18-3.35), and spina bifida (OR 1.93; 95%CI 1.25-2.98). Hypospadias (males only) was inversely related to UOGD exposure (OR: 0.62, 95% CI: 0.43-0.91). Odds of any structural defect were greater in magnitude but less precise in analyses using the hydrological-specific metric (OR: 1.30; 95%CI: 0.85-1.90), in areas with high social vulnerability (OR: 1.27, 95% CI: 0.99-1.60), and among female offspring (OR: 1.28, 95%CI: 1.06-1.53).Conclusions: Our results suggest a positive association between UOGD and certain birth defects, and findings for neural tube defects corroborate results from prior studies.