Optimal spatiotemporal scales to aggregate satellite ocean color data for nearshore reefs and tropical coastal waters: two case studies

Remotely sensed ocean color data are useful for monitoring water quality in coastal environments. However, moderate resolution (hundreds of meters to a few kilometers) satellite data are underutilized in these environments because of frequent data gaps from cloud cover and algorithm complexities in shallow waters. Aggregating satellite data over larger space and time scales is a common method to reduce data gaps and generate a more complete time series, but potentially smooths out the small-scale, episodic changes in water quality that can have ecological influences. By comparing aggregated satellite estimates of Kd(490) with related in-water measurements, we can understand the extent to which aggregation methods are viable for filling gaps while being able to characterize ecologically relevant water quality conditions. In this study, we tested a combination of six spatial and seven temporal scales for aggregating data from the VIIRS instrument at several coral reef locations in Maui, Hawai‘i and Puerto Rico and compared these with in situ measurements of Kd(490) and turbidity. In Maui, we found that the median value of a 5-pixels, 7-days spatiotemporal cube of satellite data yielded a robust result capable of differentiating observations across small space and time domains and had the best correlation among spatiotemporal cubes when compared with in situ Kd(490) across 11 nearshore sites (R2 = 0.84). We also found long-term averages (i.e., chronic condition) of VIIRS data using this aggregation method follow a similar spatial pattern to onshore turbidity measurements along the Maui coast over a three-year period. In Puerto Rico, we found that the median of a 13-pixels, 13-days spatiotemporal cube of satellite data yielded the best overall result with an R2 = 0.54 when compared with in situ Kd(490) measurements for one nearshore site with measurement dates spanning 2016–2019. As spatiotemporal cubes of different dimensions yielded optimum results in the two locations, we recommend local analysis of spatial and temporal optima when applying this technique elsewhere. The use of satellite data and in situ water quality measurements provide complementary information, each enhancing understanding of the issues affecting coastal ecosystems, including coral reefs, and the success of management efforts

Performance and Sustainability Tradeoffs of Oxidized Carbon Nanotubes as a Cathodic Material in Lithium‐Oxygen Batteries

Climate change mitigation efforts will require a portfolio of solutions, including improvements to energy storage technologies in electric vehicles and renewable energy sources, such as the high‐energy‐density lithium‐oxygen battery (LOB). However, if LOB technology will contribute to addressing climate change, improvements to LOB performance must not come at the cost of disproportionate increases in global warming potential (GWP) or cumulative energy demand (CED) over their lifecycle. Here, oxygen‐functionalized multi‐walled carbon nanotube (O‐MWCNT) cathodes were produced and assessed for their initial discharge capacities and cyclability. Contrary to previous findings, the discharge capacity of O‐MWCNT cathodes increased with the ratio of carbonyl/carboxyl moieties, outperforming pristine MWCNTs. However, increased oxygen concentrations decreased LOB cyclability, while high‐temperature annealing increased both discharge capacity and cyclability. Improved performance resulting from MWCNT post‐processing came at the cost of increased GWP and CED, which in some cases was disproportionately higher than the level of improved performance. Based on the findings presented here, there is a need to simultaneously advance research in improving LOB performance while minimizing or mitigating the environmental impacts of LOB production.Green in the (power) bank: Altering the properties, structures, and surface chemistry of multi‐walled carbon nanotubes can make them more effective Li‐air battery cathodes, but only annealing and select oxidation techniques lead to a net environmental benefit.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166425/1/cssc202002317.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/166425/2/cssc202002317_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/166425/3/cssc202002317-sup-0001-misc_information.pd

The effect of sucralose on flavor sweetness in electronic cigarettes varies between delivery devices.

The appeal of sweet electronic cigarette flavors makes it important to identify the chemical compounds that contribute to their sweetness. While volatile chemicals that produce sweet aromas have been identified in e-liquids, there are no published reports of sugars or artificial sweeteners in commercial e-liquids. However, the sweetener sucralose is marketed as an e-liquid additive to commercial flavors. The primary aims of the study were to determine if sucralose is delivered in sufficient concentration in the inhaled aerosol to enhance flavor sweetness, and whether the amount delivered depends on the e-liquid delivery system. Thirty-two adult smokers rated flavor intensity, sweetness, harshness and liking/disliking for 4 commercial flavors with and without sucralose (1%) using 2 e-cigarette delivery systems (cartridge and tank). Participants alternately vaped normally or with the nose pinched closed to block perception of volatile flavor components via olfaction. LC/MS was used to measure the concentration of sucralose in the e-liquid aerosols using a device that mimicked vaping. Sweetness and flavor intensity were perceived much more strongly when olfaction was permitted. The contribution of sucralose to sweetness was significant only for the cartridge system, and the chemical analysis showed that the concentration of sucralose in the aerosol was higher when the cartridge was used. Together these findings indicate that future regulation of sweet flavor additives should focus first on the volatile constituents of e-liquids with the recognition that artificial sweeteners may also contribute to flavor sweetness depending upon e-cigarette design

Sustainable off-grid desalination of hypersaline waters using Janus wood evaporators

A sustainable Janus wood evaporator with asymmetric surface wettability shows persistent salt-resistance for off-grid hypersaline waters desalination.</jats:p

Quantification of Flavorants and Nicotine in Waterpipe Tobacco and Mainstream Smoke and Comparison to E-cigarette Aerosol

Abstract Introduction Waterpipe use remains popular among youth with the availability of flavored shisha tobacco being one of the main drivers of waterpipe use. Although waterpipe mainstream toxicant emissions are well understood, less is known about the carryover of flavorants such as vanillin, benzaldehyde, and eugenol. In this study, flavored waterpipe tobacco was analyzed for flavorants and nicotine, and subsequent carryover to mainstream smoke. Methods Flavorants vanillin, benzaldehyde, and eugenol, and nicotine were quantified in vanilla-, cherry-, and cinnamon-flavored shisha tobacco by gas chromatography/flame ionization detector and subsequently in waterpipe mainstream smoke generated by a smoking machine. The setup allowed for sampling before and after the water-filtration step. Results Flavorant and nicotine content in smoke was reduced 3- to 10-fold and 1.4- to 3.1-fold, respectively, due to water filtration. Per-puff content of filtered waterpipe mainstream smoke ranged from 13 to 46 µg/puff for nicotine and from 6 to 55 µg/puff for flavorants. Conclusions Although water filtration reduced flavor and nicotine content in waterpipe mainstream smoke, the detected flavorant concentrations were similar or higher to those previously reported in e-cigarette aerosol. Therefore, users could be drawn to waterpipes due to similar flavor appeal as popular e-cigarette products. Absolute nicotine content of waterpipe smoke was lower than in e-cigarette aerosol, but the differential use patterns of waterpipe (&amp;gt;100 puffs/session) and e-cigarette (mostly &amp;lt;10 puffs/session, multiple session throughout the day) probably result in higher flavorant and nicotine exposure during a waterpipe session. Strategies to reduce youth introduction and exposure to nicotine via waterpipe use may consider similar flavor restrictions as those for e-cigarettes. Implications Although waterpipe mainstream smoke is well characterized for toxicants content, little is known about carryover of molecules relevant for appeal and addiction: flavorants and nicotine. This study shows that flavorant content of waterpipe mainstream smoke is comparable or higher than e-cigarette aerosol flavorant content. Regulatory action to address tobacco use behaviors targeting the availability of flavors should also include other tobacco products such as flavored shisha tobacco. </jats:sec

Sustainable Zero Liquid Discharge of Concentrated Brine by Janus Wood Evaporator

Abstract Solar-driven distillation is a promising technology for energy-efficient freshwater generation, but salt accumulation on solar absorbers and system longevity are major challenges that hinder its widespread application. In this study, we present a novel Janus wood evaporator that overcame these challenges and achieved record-high evaporation efficiencies in high-salinity brine, one of the most difficult water sources to treat using desalination. The Janus wood evaporator had an asymmetric surface wettability, where the top layer acted as a hydrophobic solar absorber with enhanced thermal insulation, while the bottom hydrophilic wood layer allowed for rapid water replenishment. An evaporation efficiency of 82.0% was achieved for 20% NaCl solution, and superior salt-resistance was observed during a 10-cycle longevity test. To ensure the environmental sustainability of the new Janus wood evaporator, a life cycle assessment (LCA) was conducted to compare this Janus wood evaporator to emerging Janus evaporators. Results showed that Janus wood evaporators could emit up to two orders of magnitude less CO2 equivalents than an aerogel Janus evaporator (AJE) and up to 80% fewer emissions than an electrospun Janus mat (EJM), indicating a functional and more sustainable opportunity for off-grid industrial applications and humanitarian efforts.</jats:p

Underestimation of Sector-Wide Methane Emissions from United States Wastewater Treatment

An increasing percentage of US waste methane (CH4) emissions come from wastewater treatment (10% in 1990 to 14% in 2019), although there are limited measurements across the sector, leading to large uncertainties in current inventories. We conducted the largest study of CH4 emissions from US wastewater treatment, measuring 63 plants with average daily flows ranging from 4.2 × 10–4 to 8.5 m3 s–1 (<0.1 to 193 MGD), totaling 2% of the 62.5 billion gallons treated, nationally. We employed Bayesian inference to quantify facility-integrated emission rates with a mobile laboratory approach (1165 cross-plume transects). The median plant-averaged emission rate was 1.1 g CH4 s–1 (0.1–21.6 g CH4 s–1; 10th/90th percentiles; mean 7.9 g CH4 s–1), and the median emission factor was 3.4 × 10–2 g CH4 (g influent 5 day biochemical oxygen demand; BOD5)−1 [0.6–9.9 × 10–2 g CH4 (g BOD5)−1; 10th/90th percentiles; mean 5.7 × 10–2 g CH4 (g BOD5)−1]. Using a Monte Carlo-based scaling of measured emission factors, emissions from US centrally treated domestic wastewater are 1.9 (95% CI: 1.5–2.4) times greater than the current US EPA inventory (bias of 5.4 MMT CO2-eq). With increasing urbanization and centralized treatment, efforts to identify and mitigate CH4 emissions are needed