Ecological Implications of Aging and Obsolete Water Infrastructure

Society relies on streams and rivers to perform valuable ecosystem services, yet streams in human-developed landscapes typically have altered ecosystem structure and function compared to streams in more natural settings. Aging and obsolete water infrastructure is a critical, global problem threatening freshwater systems and compromising economic stability, human welfare, and the environment. Globally, local resource managers are tasked to address environmental and human-health concerns associated with aging and obsolete water infrastructure using limited financial resources. Nevertheless, we have a limited understanding of how waste streams may differentially effect ecosystem structure and function through space and time—water-infrastructure decisions at the local level may have large ecological and socioeconomic impacts downstream. Research in the Capps Labe will generate information relevant to supporting local decision-making pertaining to wastewater treatment and other water infrastructure decisions throughout the globe.

Research in river ecosystem ecology has demonstrated the importance of how upstream (e.g., the River Continuum Concept), lateral (e.g., Flood Pulse), and local (e.g., functional processing zones) conditions influence metabolic processes in rivers and the relationships between aquatic communities and food resources. A rich body of work has also demonstrated the potential impact consumers can have on mediating the flow of energy and elements across habitat boundaries, but much less attention has been given to understanding the impact anthropogenically-mediated subsidies can have on energy and elemental cycling within streams and rivers. As human population continues to grow and the world continues to urbanize, a paradigm shift in how ecologists consider the impacts of human waste in freshwaters is needed to accurately describe ecosystem structure and function in rivers, and to predict how freshwater structure and function will change with increasing anthropogenic pressures. Collectively, these projects will generate some of the data needed to support this shift in our thinking, and will inform our understanding of spatial and temporal variation in the factors mediating riverine productivity respiration, and nutrient cycling in temperate and tropical watersheds.  Some of the on-going projects and our local, national, and international collaborations are  described below.

Relevant Publications:

Capps, K. A., Bateman McDonald, J. M., Gaur, N., & Parsons, R. (2020). Assessing the socio-environmental risk of onsite wastewater treatment systems to inform management decisions. Environmental Science & Technology, 54: 14843-14853. https://doi.org/10.1021/acs.est.0c03909

Capps, K. A. (2019). Wastewater infrastructure and the ecology and management of freshwater systems. Acta Limnologica Brasiliensia 31. http://dx.doi.org/10.1590/s2179-975×3719

Capps, K. A., Bentsen, C. N., & Ramírez, A. (2016). Poverty, urbanization, and environmental degradation: urban streams in the developing world. Freshwater Science 35: 429-435. https://doi.org/10.1086/684945

Cease, A. J., Capps, K. A., Gates, K. K., McCrackin, M. L., & Nidzgorski, D. A. (2015). Consumer‐driven nutrient dynamics in urban environments: the stoichiometry of human diets and waste management. Oikos 124: 931-948. https://doi.org/10.1111/oik.02391

Roy, A. H., Capps, K. A., El-Sabaawi, R. W., Jones, K. L., Parr, T. B., Ramírez, A., … & Wenger, S. J. (2016). Urbanization and stream ecology: diverse mechanisms of change. Freshwater Science 35: 272-277. https://doi.org/10.1086/685097

Anthropogenically-Derived Subsidies in Temperate and Tropical Systems

Award Abstract #1941555
NSF CAREER: THE IMPACTS OF ANTHROPOGENICALLY-DERIVED SUBSIDIES ON FRESHWATER ECOSYSTEMS

Rivers and streams provide important services, such as drinking water, fisheries, and recreational opportunities. Yet, the integrity of rivers and streams throughout the globe is compromised by pollution from aging and obsolete wastewater infrastructure. Currently, there is limited understanding of how human waste affects stream communities and ecosystem processes. The project will integrate field observations, experiments, and modelling, to advance our understanding of how rivers and streams are affected by wastewater infrastructure, and will provide new insights into interactions between civil and environmental engineering and ecosystem science. This CAREER award will support the training and development of high school students, graduate students, and a postdoctoral researcher.

Understanding the spatial and temporal variation in the factors influencing riverine structure and function is essential to predict how fresh waters will respond to continued anthropogenic change. This CAREER award will couple field observations with field- and lab-based experiments and modelling, to examine: 1) spatial and temporal variation in the quality, quantity, and relative volume of wastewater entering river systems, 2) the effects of wastewater on seasonal and annual patterns of metabolic processes flowing waters, 3) the influence of interactions between wastewater and ambient nutrient concentrations on trophic relationships and on the tissue and mineralization stoichiometry of consumers, and 4) the extent to which consumers transport wastewater-derived energy and elements to resource-limited systems within river networks. The award will integrate wastewater discharge into a spatial subsides framework to support more accurate predictions for how wastewater structures aquatic communities and alters biogeochemical processes in river networks. Moreover, the award will generate the data needed to compare seasonal and annual patterns in riverine metabolic processes in large, tropical rivers. The research will also test how flexibility in the trophic and stoichiometric traits of consumers governs the role they play in biogeochemical cycling under variable environmental conditions. Educational modules and service-learning projects in introductory environmental science and advanced ecology courses will be developed. High school students will be trained in stream ecology and provided internships with the local government and freshwater conservation organizations. Additionally, this research will have important management implications, as governments throughout the globe are challenged to fix wastewater effects on water quality, human health, and biodiversity.

Nacional de Ciencia y Tecnología (CONACYT), México (217368): Metabolismo del ecosistema en ríos tropicales: la influencia de la estacionalidad hidrológica y las presiones humanas (Ecosystem metabolism in tropical rivers: the influence of hydrological seasonality and human pressures).

Lead PIs: MM Castillo, M Cazanelli, El Colegio de la Frontera Sur (ECOSUR), México. Co-PIs: W. Arévalo Frías (UJAT), K. Capps, A. (UGA), Jarquín Sánchez (ECOSUR), M Mendoza Carranza (ECOSUR), A. Mesa Jurado (ECOSUR), D. Ramos Muñoz (ECOSUR), R. Rodies Hernández (ECOSUR), A. Ulseth (SHSU)

Ecosystem metabolism is an integrative measure of river functioning because it considers autotrophic and heterotrophic processes in different riverine habitats. Metabolism is the balance between gross primary productivity (GPP) and ecosystem respiration (ER) showing temporal and longitudinal variation in a river network. Most metabolism studies have been conducted in temperate streams using dissolved oxygen measurements during short time periods. However, recent development of sensors that can measure and record oxygen concentrations for longer periods have contributed to identify temporal patterns in metabolism in temperate streams and rivers. Despite these advances, larger rivers, particularly those located in the tropics are less understood. In contrast to temperate rivers, temperature and irradiance are relatively stable through the year in tropical systems, and hydrological seasonality may play a much more important role governing GPP and ER. Human activities, such as dam construction and land use change, are expected to affect metabolic regimes by altering the timing and intensity of GPP and ER. Fluctuations in GPP and ER associated with hydrological seasonality and responses to human pressures may influence temporal and spatial variation in the quality and quantity of energy available to support aquatic food webs. Thus, our objective is to evaluate the responses of ecosystem metabolism to hydrological seasonality and anthropogenic pressures in tropical rivers and how these responses influence energy sources and food webs. 

Anthropogenic subsidies (i.e., human waste) may be an important source of nutrients, especially in nutrient-limited systems. Relationship between nitrate and soluble reactive phosphorus (SRP) concentrations from the water column (ambient; white) and in wastewater discharge (subsidy; black) entering the Grijalva (○) and Usumacinta (□) basins. In general, phosphorus concentrations of subsidies are higher than ambient phosphorus concentrations and they are a consistently rich source of phosphorus. Modified from Capps 2019.

Freshwater Ecology and Wastewater Infrastructure in the Southeast

Much of the work below is being conducted in conjunction with the BioGeo Poop Group at UGA (Capps, Gaur, and Abney Labs). We are also collaborating with the Bledsoe Environmental Engineering Lab,  the Bier and Ottesen Microbial Ecology Labs, the Rice Political Geography Lab, the Tennessee Aquarium, the 

Metropolitan North Georgia Water Planning District, and most importantly the Athens-Clarke County Government. We have detailed some, but not all of the projects associated with this research below. 

Local governments are often challenged to manage the impacts of complex networks of aging and obsolete wastewater networks on human health and the environment with very limited data to inform their decisions. Unlike sewerage, which is often monitored and maintained by local governments in perpetuity, onsite waste systems are typically managed by individual landowners after they are installed and municipal intervention by public health officials only occurs when system failure presents a risk to the community. Integrated networks of communication between public health officials and water resource managers can be limited; hence, many local governments do not have the information needed to assess how the location and condition of septic infrastructure may threaten the integrity of surface waters. Collectively, these projects attempt to generate some of this information.

Award Abstract #1952183
SCC-PG Smart Septic Strategies: Data Integration to Manage Hidden Infrastructure Threats to Our Homes and Communities

Residential systems collect and treat wastewater from home toilets, sinks, baths, and washing appliances and are a key component of the water infrastructure of the United States. Approximately one in four U.S. households relies on septic systems to treat their wastewater. Most of this vast hidden infrastructure is poorly maintained and periodically overloaded by periods of high water use and/or household leaks. Improving the functionality of these systems will lead to significant improvements to public health and environmental quality by reducing the volumes of untreated or under-treated wastewater released into the environment, which in turn will reduce exposures to dangerous pathogens in groundwater and surface waters, improve aquatic ecosystem health by reducing excess nutrient discharges, and avoid economic losses of closed fishing areas and beaches associated with high bacterial levels in the water. The results of this project will ultimately enable the development of smart septic systems, improved infrastructure asset management, and reduced threats to homes, health, water supplies, and the natural environment.

This project will be the first to integrate high quality data on household-scale water use and leak patterns from existing smart water meters, in situ sensor measurements of septic system behavior, automated processing of infrared (IR) aerial imagery that can show septic system failure, and continuous monitoring of septic contamination in community streams with water quality sensors to enable smart septic systems, infrastructure asset management, and reduced threats to homes, health, and water supplies. The project will also create innovative data analytics tools that will generate household water usage profile breakdowns for specific fixtures and appliances, and further detect, classify and quantify water leakages and the impact to septic tank failures. The development of these processes and constituent technology will be performed in close collaboration with septic management and regulatory officials as the state, regional, and local level to ensure that the processes and products that result from this research will a meaningful real-world impact on this important and long-neglected issue.

Award Abstract #2035534
RAPID: Soil and water biogeochemical response to COVID-19: increased stress on septic systems alters soil and water quality

Early in 2020 northeast Georgia had much higher rainfall than normal placing increased stress on aging septic systems in the region. Additionally, shelter-in-place and social distancing policies related to the COVID-19 pandemic have increased the time residents spend at home and therefore the use of residential septic wastewater treatment systems. This increased stress on septic systems may change soil properties and pollutant content in septic leach fields. This project will investigate how increased septic system use could lead to pollutant runoff. Septic systems will be investigated inside and outside of the leach field perimeter and the soil physical, hydrologic, and chemical properties analyzed in the field and with laboratory methods. The results from this study will inform land managers and local governments on pollutants that need to be managed to protect human health, natural resources, and the environment. Educational materials will be prepared and distributed at the annual Athens Water Festival. One graduate student will be directly involved in the project and will be trained in a wide selection of field and laboratory techniques.

The object of this project is to investigate the current period of intensive rainfall and septic system use and how it may generate novel hotspots of biogeochemical activity in both soil and soil water. The core hypothesis is that enhanced nutrient loading in septic leach fields during this period of increased septic stress (COVID-19 and weather related) will drive shifts in quantity and composition of organic matter in soil and soil water, along with shifts in overall biogeochemical cycling. This research project will address three objectives: 1. Estimate the impact of leach fields on soil and soil water biogeochemistry using a comparative approach. 2. Identify potential hotspots of change in nutrients and soil organic matter with enough spatial and temporal resolution to generate larger-scale hotspot predictions. 3. Estimate potential nutrient and organic matter loading being delivered to water bodies from related stress in septic system functioning and to septic system maintenance. By investigating the impacts of extreme weather events and increased septic system demand, this work will provide critical insights to shifts in soil water and related aquatic nutrient loading. Understanding these shifts will provide local governments information related to long-term use of septic systems, and management challenges related to future climate regimes. The PIs anticipate working with local agencies and outreach specialists to develop new septic educational material to be distributed at the annual Athens Water Festival, taking advantage of an on-going collaboration with Clarke County. The PI is a new researcher, and one graduate student will be directly involved in the project and will be trained in a wide selection of field and laboratory techniques.

Carbon Dynamics in Urbanizing Watersheds

Award Abstract #2015619
Collaborative Research: Scales and drivers of variability in dissolved organic carbon across diverse urban watersheds

Project Lead PI: Rebecca Hale, Idaho State; Co-PIs: Krista Capps (UGA), Krissy Hopkins (USGS), John Kominoski (FIU), Jennifer Morse (PSU), Allison Roy (UMass).

Most ecosystems are impacted by human activities to some degree, but this can vary considerably beteween locations. For example, cities differ in their impacts on streams and rivers depending on age, storm water infrastructure, amount of green space, and other factors of the built environment. Natural factors such as climate (temperature and precipitation) and geology also affect how different cities influence water quality and quantity at different times of the year. In this project, differences in urban impacts on carbon inputs and outputs in streams will be evaluated across cities in the U.S. that have different urban and climate contexts. This research is critical for understanding ecological patterns and processes in urban streams. Broader impacts of the work will include training opportunities for undergraduate and graduate students and postdoctoral scholars, workshops, and an innovative training and internship program for high school students.

This study will take a novel approach to jointly consider how the human and ecological dimensions of ecosystem ecology interact to control the quality, quantity, and timing of dissolved organic carbon (DOC)–the largest flux of carbon in streams –entering watersheds across the continent. This project will assess how urbanization affects DOC, focusing on how urbanization affects stream ecosystems in regionally-specific ways. Researchers will test the hypothesis that human activities introduce novel sources of DOC and affect the spatial and temporal scales and variability of ecological processes in different geographies and urban contexts. The hypothesis will be tested using a comparative approach to understand urban effects on DOC in five urban study areas ? Miami, FL, Boston, MA, Atlanta, GA, Salt Lake City, UT, and Portland, OR. Extensive synoptic sampling of DOC concentrations and quality will be combined with intensive sensor networks to develop a multi-scale understanding of the quantity and quality of DOC in urban systems. Spatial statistics and time-series analyses will identify key spatio-temporal characteristics of human development (e.g., wastewater infrastructure, housing density) and biophysical factors (e.g., discharge, precipitation, canopy cover) that control the concentration, characteristics, and bioavailability of DOC.