Greenhouse gases and green roofs: carbon dioxide and methane fluxes in relation to substrate characteristics

Green roof systems have been increasingly implemented to enhance vegetation cover and associated ecosystem services in urban spaces, with primary goals being the reduction of peak surface runoff, enhanced water quality, and mitigation of urban heat island effects. Recently, green roofs have also received attention as a means to enhance carbon sequestration, but direct measurements of greenhouse gas fluxes from established green roof systems are largely lacking. Here we present observations of CO₂ and CH₄ fluxes from substrates of experimental extensive green roof units that varied in vegetation type (Sedum spp., and a native meadow species mix), substrate depth, substrate type (high vs. low organic matter content), and irrigation. We predicted that substrate CO₂ effluxes would be higher in high-organic-matter substrates and that systems with high organic matter would potentially act as CH₄ sources. Substrate fluxes were low compared to natural soils, with seasonal means ranging from an efflux of 0.1–0.4 µmol CO₂ m^-2.s^-1 and uptake of ~0.00–0.04 nmol CH₄ m^-2.s^-1, with higher fluxes late in the growing season. CO₂ fluxes showed large increases in response to irrigation and were higher from the high-organic-matter substrate and with increased substrate depth. The strength of the CH₄ sink increased in response to prior irrigation treatments, and CH₄ emissions were detected only on low-organic-matter substrates early in the growing season. No effects of vegetation type were detected for either CO₂ or CH₄ flux. Our results indicate that high levels of organic matter in green roof substrates may enhance aerobic soil respiration but are not associated with CH₄ emissions, which instead were only detected in low-organic-matter substrates.

     

Media exposure,threat processing,and mitigation behaviors in Gulf Coast residents facing the co-occurring threats of COVID-19 and hurricanes

The 2020 hurricane season threatened millions of Americans concurrently grappling with COVID-19. Processes guiding individual-level mitigation for these conceptually distinct threats, one novel and chronic (COVID-19), the other familiar and episodic (hurricanes), are unknown. Theories of health protective behaviors suggest that inputs from external stimuli (e.g., traditional and social media) lead to threat processing, including perceived efficacy (self- and response) and perceived threat (susceptibility and severity), guiding mitigation behavior. We surveyed a representative sample of Florida and Texas residents (N = 1846) between April 14, 2020 and April 27, 2020; many had previous hurricane exposure; all were previously assessed between September 8, 2017 and September 11, 2017. Using preregistered analyses, two generalized structural equation models tested direct and indirect effects of media exposure (traditional media, social media) on self-reported (1) COVID-19 mitigation (handwashing, mask-wearing, social distancing) and (2) hurricane mitigation (preparation behaviors), as mediated through perceived efficacy (self- and response) and perceived threat (susceptibility and severity). Self-efficacy and response efficacy were associated with social distancing (p = .002), handwashing, mask-wearing, and hurricane preparation (ps < 0.001). Perceived susceptibility was positively associated with social distancing (p = 0.017) and hurricane preparation (p < 0.001). Perceived severity was positively associated with social distancing (p < 0.001). Traditional media exhibited indirect effects on COVID-19 mitigation through increased response efficacy (ps < 0.05), and to a lesser extent self-efficacy (p < 0.05), and on hurricane preparation through increased self-efficacy and response efficacy and perceived susceptibility (ps < 0.05). Social media did not exhibit indirect effects on COVID-19 or hurricane mitigation. Communications targeting efficacy and susceptibility may encourage mitigation behavior; research should explore how social media campaigns can more effectively target threat processing, guiding protective actions.     

Religiosity,sexual behaviors,sexual motivations,and gender: A three-year longitudinal study

Longitudinal data are critical for examining associations of religiosity with sexual behaviors and motivations during college. We use hierarchical linear modeling on five semesters of data from a diverse sample of college students (N = 735) to examine within- and between-person associations between religious service attendance and importance of religion and sexual behaviors and motivations for and against sex and consider gender as a moderator. Between-person religiosity was associated with sexual behaviors and motivations whereas within-person religiosity was not. Students' sexual motivations co-varied across semesters with their religious service attendance and importance of religion. Our results indicated more restrictive associations between religiosity and sexual motivations for women than for men.     

FINANCIAL INTEGRATION: A NEW METHODOLOGY AND AN ILLUSTRATION

This paper develops a simple methodology to test for asset integration, and applies it within and between American stock markets. Our technique relies on estimating and comparing expected risk‐free rates across assets. Expected risk‐free rates are allowed to vary freely over time, constrained only by the fact that they must be equal across (risk‐adjusted) assets in well‐integrated markets. Assets are allowed to have standard risk characteristics, and are constrained by the Fama and French factor model of covariances over short time periods. We find that internal integration in the S&P 500 market is never rejected and is not generally rejected in the NASDAQ. Integration between the NASDAQ and the S&P, however, is always rejected dramatically. (JEL: G14)