Development and validation of in-situ and laboratory X-ray fluorescence (XRF) spectroscopy methods for moss biomonitoring of metal pollution.

Metals are among the pollutants of highest concern in urban areas due to their persistence, bioavailability and toxicity. High concentrations of metals threaten aquatic ecosystem functioning and biodiversity, as well as human health. High-resolution estimates of pollutant sources are required to mitigate exposure to toxic compounds by identifying the specific locations and associated site characteristics where the deposition of metals is greatest. Mosses have been widely used as low-cost biological monitors of metal pollution for decades, because they readily accumulate pollutants over time, reflecting long term pollution levels. However, spectroscopic techniques to determine the concentration of metal pollutants in moss samples still require expensive instrumentation and involve time consuming sample preparation protocols with heavy use of reagents. Here we present protocols to perform in-situ and laboratory X-ray fluorescence (XRF) spectroscopy of epiphytic moss as rapid, low-cost, and accurate alternatives to conventional metal pollution biomonitoring. We also report on a preliminary validation of the measurements using mass fractions determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES) as reference.•XRF measurements are taken from moss directly on tree trunks in less than five minutes.•Grinding and pelletizing of moss enables definitive quantitation (R2>0.90) of metals through portable XRF.

Low-cost biomonitoring and high-resolution, scalable models of urban metal pollution.

As the global toll on human lives and ecosystems exacted by urban pollution grows, planning tools still lack the resolution to identify priority sites where toxic pollution can be most efficiently averted at a spatial scale that matches funding and management. Here we tackle this gap by demonstrating novel scalable methods to monitor and predict urban metal pollution at high resolution (<5 m) across large areas (10,000-100,000 km2) to guide pollution reduction and stormwater management. We showcase and calibrate predictive models of Zn, Cu, and a synthetic index of pollution for the Puget Sound region of Washington State, U.S., a densely urbanized yet important ecosystem of conservation interest, and exemplify their transferability across the entire United States. We leveraged widely and freely available datasets of car traffic characteristics and land use as predictor variables and trained the models with biological monitoring data of metal concentrations in epiphytic moss from >100 trees based on new rapid and low-cost protocols introduced in this study. Our model predictions, showing that 50% of the total Cu and Zn pollution across the Puget Sound watershed is deposited over only 3.3% of the land area, will allow cities to effectively and efficiently target toxic hotspots.

Assessing the flow to low-income urban areas of conservation and environmental funds approved by California's Proposition 84.

Government funding accounts for a large proportion of conservation and environmental improvements, and is often the result of citizen votes on state ballot measures. A key concern surrounding public investments in the environment is whether that funding serves lower-income communities, which are often the communities of greatest need. We applied three statistical methods to analyze the spatial distribution of conservation funding derived from California's Proposition 84, which distributed nearly $4 billion across California between 2006 and 2015. First, we used hurdle models to ask if income, population density, urban coverage, or pollution could explain receipt of grants or magnitude of funding. Second, we compared the income levels of funded and unfunded communities for each chapter of the proposition. Finally, we examine two sections of the proposition that were intended to fund parks around the state and compare the attributes of funded and unfunded communities. Proposition 84 offers lessons for environmental legislation and future research. While there were general tendencies for more funding to flow to poor areas and areas with pollution problems, the language in Proposition 84 as a whole was vague with respect to the funding of disadvantaged areas, and as a result the targeting of these areas overall was at best modest. However, when enabling legislation (AB 31) defined specific "metrics of disadvantage" that had to be met by communities to receive funds from some sections of Proposition 84, the funds did flow much more selectively to poorer communities. This suggests that future ballot measures should be very explicit in their language if they want to promote equity in conservation investments, and that future research should investigate the extent to which technical workshops and outreach could further increase the number of funded grant proposals from low-income communities.

The unequal vulnerability of communities of color to wildfire.

Globally, environmental disasters impact billions of people and cost trillions of dollars in damage, and their impacts are often felt most acutely by minority and poor communities. Wildfires in the U.S. have similarly outsized impacts on vulnerable communities, though the ethnic and geographic distribution of those communities may be different than for other hazards. Here, we develop a social-ecological approach for characterizing fire vulnerability and apply it to >70,000 census tracts across the United States. Our approach incorporates both the wildfire potential of a landscape and socioeconomic attributes of overlying communities. We find that over 29 million Americans live with significant potential for extreme wildfires, a majority of whom are white and socioeconomically secure. Within this segment, however, are 12 million socially vulnerable Americans for whom a wildfire event could be devastating. Additionally, wildfire vulnerability is spread unequally across race and ethnicity, with census tracts that were majority Black, Hispanic or Native American experiencing ca. 50% greater vulnerability to wildfire compared to other census tracts. Embracing a social-ecological perspective of fire-prone landscapes allows for the identification of areas that are poorly equipped to respond to wildfires.

The use of fluorescein in contact lens aftercare.

This short communication reports on the responses of a cohort of more than 2000 contact lens practitioners across five European countries, who were surveyed on the routine use of fluorescein in soft contact lens aftercare. Although corneal staining has received extensive interest amongst the academic community, most practitioners do not routinely use fluorescein at aftercare visits. The arguments for not using the agent seem to be somewhat flawed in modern contact lens practice and it is hoped by education and wider communications of the value of staining that more practitioners use it more often.