Building resilience to extreme weather events in Phoenix: Considering contaminated sites and disadvantaged communities.

The interplay of contaminated sites, climate change, and disadvantaged communities are a growing concern worldwide. Worsening extreme events may result in accidental contaminant releases from sites and waste facilities that may impact nearby communities. If such communities are already suffering from environmental, economic, health, or social burdens, they may face disproportionate impacts. Equitable resilience planning to address effects of extreme events requires information on where the impacts may be, when they may occur, and who might be impacted. Because resources are often scarce for these communities, conducting detailed modeling may be cost-prohibitive. By considering indicators for four sources of vulnerability (changing extreme heat conditions, contaminated sites, contaminant transport via wind, and population sensitivities) in one holistic framework, we provide a scientifically robust approach that can assist planners with prioritizing resources and actions. These indicators can serve as screening measures to identify communities that may be impacted most and isolate the reasons for these impacts. Through a transdisciplinary case study conducted in Maricopa County (Arizona, USA), we demonstrate how the framework and geospatial indicators can be applied to inform plans for preparedness, response, and recovery from the effects of extreme heat on contaminated sites and nearby populations. The indicators employed in this demonstration can be applied to other locations with contaminated sites to build community resilience to future climate impacts.

A synthesis of ecosystem management strategies for forests in the face of chronic nitrogen deposition.

Total nitrogen (N) deposition has declined in many parts of the U.S. and Europe since the 1990s. Even so, it appears that decreased N deposition alone may be insufficient to induce recovery from the impacts of decades of elevated deposition, suggesting that management interventions may be necessary to promote recovery. Here we review the effectiveness of four remediation approaches (prescribed burning, thinning, liming, carbon addition) on three indicators of recovery from N deposition (decreased soil N availability, increased soil alkalinity, increased plant diversity), focusing on literature from the U.S. We reviewed papers indexed in the Web of Science since 1996 using specific key words, extracted data on the responses to treatment along with ancillary data, and conducted a meta-analysis using a three-level variance model structure. We found 69 publications (and 2158 responses) that focused on one of these remediation treatments in the context of N deposition, but only 29 publications (and 408 responses) reported results appropriate for our meta-analysis. We found that carbon addition was the only treatment that decreased N availability (effect size: -1.80 to -1.84 across metrics), while liming, thinning, and prescribed burning all tended to increase N availability (effect sizes: +0.4 to +1.2). Only liming had a significant positive effect on soil alkalinity (+10.5%-82.2% across metrics). Only prescribed burning and thinning affected plant diversity, but with opposing and often statistically marginal effects across metrics (i.e., increased richness, decreased Shannon or Simpson diversity). Thus, it appears that no single treatment is effective in promoting recovery from N deposition, and combinations of treatments should be explored. These conclusions are based on the limited published data available, underscoring the need for more studies in forested areas and more consistent reporting suitable for meta-analyses across studies.

Pathogen reduction co-benefits of nutrient best management practices.

BACKGROUND: Many of the practices currently underway to reduce nitrogen, phosphorus, and sediment loads entering the Chesapeake Bay have also been observed to support reduction of disease-causing pathogen loadings. We quantify how implementation of these practices, proposed to meet the nutrient and sediment caps prescribed by the Total Maximum Daily Load (TMDL), could reduce pathogen loadings and provide public health co-benefits within the Chesapeake Bay system. METHODS: We used published data on the pathogen reduction potential of management practices and baseline fecal coliform loadings estimated as part of prior modeling to estimate the reduction in pathogen loadings to the mainstem Potomac River and Chesapeake Bay attributable to practices implemented as part of the TMDL. We then compare the estimates with the baseline loadings of fecal coliform loadings to estimate the total pathogen reduction potential of the TMDL. RESULTS: We estimate that the TMDL practices have the potential to decrease disease-causing pathogen loads from all point and non-point sources to the mainstem Potomac River and the entire Chesapeake Bay watershed by 19% and 27%, respectively. These numbers are likely to be underestimates due to data limitations that forced us to omit some practices from analysis. DISCUSSION: Based on known impairments and disease incidence rates, we conclude that efforts to reduce nutrients may create substantial health co-benefits by improving the safety of water-contact recreation and seafood consumption.