The integration of Urban Ecological Infrastructure (UEI) has gained attention as cities seek to address challenges posed by urbanization. Constructed treatment wetlands (CTWs), commonly used for removing pollutants from wastewater effluent and storm water runoff, have been proposed as a solution to address challenges posed by rising water challenges. CTWs serve as a unique type of UEI and provide a range of ecosystem services in urban landscapes. With current global concerns over water scarcity and sustainable resource management, wetlands emerge as key components, providing vital ecosystem services, one of which is nutrient filtration. Nitrogen pollution in water bodies poses significant environmental and public health concerns, emphasizing the need for effective mitigation strategies. CTWs present a promising solution for addressing nitrogen pollution in urban settings. However, there are gaps in understanding wetland functioning within arid environments, necessitating arid climate studies to explain nitrogen dynamics. This study, conducted in the Tres Rios Wetland in Phoenix, Arizona, aims to examine nitrogen content in soils. Soil nitrogen content trends from 2019 to 2023 were investigated, with a focus on understanding nitrogen dynamics from inflow to outflow points and comparison from water to shore. There were no trends seen in nitrogen content over time from 2019 to 2023. Additionally, nitrogen levels tended to be higher at the shorelines compared to the open water, likely due to the accumulation of organic matter and soil nitrogen absorption. However, there were no trends observed in nitrogen content from the inflow to outflow points.

Plasticizers are plastic additives used to enhance the physical properties of plastic and are ubiquitous in the environment. A class of plasticizer compounds called phthalate esters that are not fully eliminated in wastewater treatment facilities are relevant to the ecological health of downstream ecosystems and urban areas due to their ecotoxicity, tendency for soil accumulation, and the emerging concern about their effects on public health. However, plasticizer concentrations in a constructed wetland environment have rarely been studied in the United States, prompting the need for a method of plasticizer quantification in the Tres Rios Constructed Wetlands which are sustained by the effluent of the 91st Avenue Wastewater Treatment Plant in Phoenix, Arizona. The concentrations of four common plasticizer compounds (dimethyl: DMP, diethyl: DEP, di-n-butyl: DnBP, and bis(2-ethylhexyl): DEHP phthalate) at five sites across the wetland surface water were quantified using solid-phase extraction followed by gas chromatography coupled with mass spectrometry (GC/MS). The sampling period included four sample sets taken from March 2022 to September 2022, which gave temporal data in addition to spatial concentration data. Quantification and quality control were performed using internal standard calibration, replicate samples, and laboratory blanks. Higher molecular weight phthalates accumulated in the wetland surface water at significantly higher average concentrations than those of lower molecular weight at a 95% confidence level, ranging from 8 ng/L to 7349 ng/L and 4 ng/L to 27876 ng/L for DnBP and DEHP, respectively. Concentrations for dimethyl phthalate and diethyl phthalate were typically less than 50 ng/L and were often below the method detection limit. Average concentrations of DnBP and DEHP were significantly higher during periods of high temperatures and arid conditions. The spatial distribution of phthalates was analyzed. Most importantly, a method for successful ultra-trace quantification of plasticizers at Tres Rios was established. These results confirm the presence of plasticizers at Tres Rios and a significant seasonal increase in their surface water concentrations. The developed analytical procedure provides a solid foundation for the Wetlands Environmental Ecology Lab at ASU to further investigate plasticizers and contaminants of emerging concern and determine their ultimate fate through volatilization, sorption, photodegradation, hydrolysis, microbial biodegradation, and phytoremediation studies.

Humans can influence wildlife populations and behavior through structural and behavioral disturbances, which can be particularly pronounced along the gradient of urbanization. Importantly, although anthropogenetic structural characteristics are relatively static along the gradient of urbanization for a given period of time, the presence of humans can be dynamic on daily and seasonal scales, which can affect wildlife activity patterns. The rapid onset of the COVID-19 pandemic created a unique opportunity to evaluate how a sudden change in human behavior can affect wildlife activity along the urbanization gradient. Specifically, we used a before-after-control-impact (BACI) study design to compare human presence and coyote daily activity patterns from before the COVID-19 pandemic to after COVID-19 stay-at-home orders and shutdowns were put in place in areas of low and high levels of urbanization. We predicted that human detection rates would increase in low levels of urbanization and decrease in high levels of urbanization due to the COVID-19 pandemic shutdowns. We also predicted that coyote daily activity patterns would shift in response to human detection rates, where coyotes would become more nocturnal in areas of low levels of urbanization where human presence was expected to increase and become more diurnal in areas of high levels of urbanization where human presence was expected to decrease. We used data from wildlife cameras across the gradient of urbanization from 2019 to 2020 within the Phoenix Valley of Arizona. Across 8 sites in low levels of urbanization and 12 sites in high levels of urbanization, we did not find a statistical difference in human detection rates or coyote activity patterns in response to the COVID-19 pandemic. However, low sample size likely led to low power to detect differences and next steps for this research (as part of my M.S. thesis project) will be incorporating additional wildlife camera locations and wildlife species (e.g., bobcat, cottontail rabbit, gray fox, etc.), into future analyses. This project and future studies can help us better understand how structural and behavioral characteristics of humans can shape wildlife populations along the gradient of urbanization, which has important conservation implications for wildlife and people.

The threat of global climate change to the world’s water resources has jeopardized access to clean drinking water across the world and continues to devastate biodiversity and natural life globally. South Africa operates as a useful case study to understand and analyze the effectiveness of public policy responses to the perils of climate change on issues of water access and ecosystem preservation. After the new South African Constitution was enacted in 1997, protecting water resources and ensuring their equitable distribution across the nation’s population was a paramount goal of the young democratic government. The National Water Act was passed in 1998, nationalizing the country’s water infrastructure and putting in place programs seeking to ensure equitable distributive and environmental outcomes. Thus far, it has failed. Access to South Africa’s water resources is as stratified as access to its economy; its aquatic ecosystems remain in grave danger; and many of the same problems of South Africa’s Apartheid era still plague its efforts to create an equitable water system. Decision-making power continues to be concentrated in the hands of the wealthy, at the expense of historically marginalized groups, whose voices are still not adequately heard. Corporate actors still exert undue influence over legislative policy that favors economic growth over environmental sustainability. The looming threat of climate change is exponentially increasing the chances of disasters like Cape Town’s 2018 feared ‘Day Zero’. The National Water Act’s noble intentions were never actualized, and therefore the people of South Africa remain in serious danger of acute and chronic threats to their water supply.

This study examines the distributional equity of urban tree canopy (UTC) cover for Baltimore, MD, Los Angeles, CA, New York, NY, Philadelphia, PA, Raleigh, NC, Sacramento, CA, and Washington, D.C. using high spatial resolution land cover data and census data. Data are analyzed at the Census Block Group levels using Spearman’s correlation, ordinary least squares regression (OLS), and a spatial autoregressive model (SAR). Across all cities there is a strong positive correlation between UTC cover and median household income. Negative correlations between race and UTC cover exist in bivariate models for some cities, but they are generally not observed using multivariate regressions that include additional variables on income, education, and housing age. SAR models result in higher r-square values compared to the OLS models across all cities, suggesting that spatial autocorrelation is an important feature of our data. Similarities among cities can be found based on shared characteristics of climate, race/ethnicity, and size. Our findings suggest that a suite of variables, including income, contribute to the distribution of UTC cover. These findings can help target simultaneous strategies for UTC goals and environmental justice concerns.

Cities around the world are facing an ever-increasing variety of challenges that seem to make more sustainable urban futures elusive. Many of these challenges are being driven by, and exacerbated by, increases in urban populations and climate change. Novel solutions are needed today if our cities are to have any hope of more sustainable and resilient futures. Because most of the environmental impacts of any project are manifest at the point of design, we posit that this is where a real difference in urban development can be made. To this end, we present a transformative model that merges urban design and ecology into an inclusive, creative, knowledge-to-action process. This design-ecology nexus—an ecology for cities—will redefine both the process and its products. In this paper we: (1) summarize the relationships among design, infrastructure, and urban development, emphasizing the importance of joining the three to achieve urban climate resilience and enhance sustainability; (2) discuss how urban ecology can move from an ecology of cities to an ecology for cities based on a knowledge-to-action agenda; (3) detail our model for a transformational urban design-ecology nexus, and; (4) demonstrate the efficacy of our model with several case studies.

Urbanization continues to be a transformative process globally, affecting ecosystem integrity and the health and well being of people around the world. Although cities tend to be centers for both the production and consumption of goods and services that degrade natural environments, there is also evidence that urban ecosystems can play a positive role in sustainability efforts. Despite the fact that most of the urbanization is now occurring in the developing countries of the Global South, much of what we know about urban ecosystems has been developed from studying cities in the United States and across Europe. We propose a conceptual framework to broaden the development of urban ecological research and its application to sustainability. Our framework describes four key contemporary urban features that should be accounted for in any attempt to build a unified theory of cities that contributes to urban sustainability efforts. We evaluated a range of examples from cities around the world, highlighting how urban areas are complex, connected, diffuse and diverse and what these interconnected features mean for the study of urban ecosystems and sustainability.

In this paper, we discuss the theoretical relationships among interacting global change risks, valued livelihood goals, and adaptation limits. We build from research on the impacts of multiple and interacting global change risks in lesser-developed countries and seek to understand household adaptation limits in agrarian communities. We ask: What are valued livelihood goals among smallholder farmers in Northwest Costa Rica? How do socio-economic determinants of adaptive capacities determine their ability to meet these goals in the face of the impacts of interacting global change risks? Our data were based on focus groups, interviews, survey responses from 94 smallholder farmers, government statistics, and published literature. We analyzed our data using qualitative content analysis and quantitative logistic regression models. Our analysis showed that farmers perceived rice production as an identity, and that they were being forced to consider limits to their abilities to adapt to maintain that identity. We found that farm size, cattle ownership, years spent farming, and household income variety were determinants of their abilities to remain in rice production while maintaining sufficient levels of livelihood security. We also showed that for those households most vulnerable to water scarcity, their ability to successfully adapt to meet valued livelihood goals is diminished because adaptation to water scarcity increases vulnerability to decreased rice-market access. In this way, they become trapped by the inability to reduce their vulnerability to risks of the interaction between global changes and therefore abandon valued identities and livelihoods.