Stephen M. PowersBaylor University | BU
Stephen M. Powers
PhD
About
41
Publications
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2,742
Citations
Citations since 2017
Additional affiliations
January 2020 - present
January 2017 - present
June 2015 - December 2016
Washington State University
Position
- PostDoc Position
Publications
Publications (41)
link to official article...
http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2693.html
Global food production depends on phosphorus. Phosphorus is broadly applied as fertilizer, but excess phosphorus contributes to eutrophication of surface water bodies and coastal ecosystems. Here we present an analysis of phosphorus fluxes in three larg...
Reproducibility is a key tenet of the scientific process that dictates the reliability and generality of results and methods. The complexities of ecological observations and data present novel challenges in satisfying needs for reproducibility, and also transparency. Ecological systems are dynamic and heterogeneous, interacting with numerous factor...
Food production hinges largely upon access to phosphorus (P) fertilizer. Most fertilizer P used in the global agricultural system comes from mining of nonrenewable phosphate rock deposits located within few countries. However, P contained in livestock manure or urban wastes represents a recyclable source of P. To inform development of P recycling t...
Mountain lakes experience interannual variability in spring snowpack and ice cover that can lead to differences in physical, chemical, and biological properties in the succeeding summer. Lake studies that capture extreme years of snow and ice would be useful to understand and anticipate effects of climate change, but such data are rare for remote m...
Our changing climate is having effects on freshwater ecosystems in all seasons, especially winter. High latitude lakes, wetlands, and rivers are experiencing shorter periods of ice cover, and lower latitudes systems that used to freeze are experiencing open water conditions throughout the winter. A 2019 AGU Chapman conference convened aquatic scien...
Millions of lakes worldwide are distributed at latitudes or elevations resulting in the formation of lake ice during winter. Lake ice affects the transfer of energy, heat, light, and material between lakes and their surroundings creating an environment dramatically different from open-water conditions. While this fundamental restructuring leads to...
Pharmaceuticals and personal care products (PPCPs) garner increasing attention globally for both their usefulness as indicators of human waste and their potency as emerging organic toxicants. Three decades of rapid increase in PPCP study combined with an increasing number of PPCPs on the global market have created opportunity (1) to review trends i...
Phosphorus is required for fertilizer for producing food, and there is no substitute. Losses between mine production and diet result in significant environmental harm. We used a demand-driven substance flow model to explore the sensitivity of global phosphorus production to interventions of the food system including: reduction in animal fraction in...
Phosphorus (P) is central to food production. Current understanding about the global phosphorus system is dominated by studies in wealthier nations where soil fertility, fertilizer supply chains, and agronomic tracking have long been established. In contrast, developing nations are experiencing major agricultural transitions and the associated phos...
The DNA of aquatic organisms can be identified in water sampled from freshwater ecosystems to detect species presence. Because these DNA-based methods (termed environmental DNA) confirm species presence by proxy of DNA in water, the processes influencing eDNA transport and removal from water are critical to the method's efficacy and interpretation...
Judicious phosphorus (P) management is a global grand challenge and critical to achieving and maintaining water quality objectives while maintaining food production. The management of point sources has been successful in lowering P inputs to aquatic environments, but more difficult is reducing P discharges associated with diffuse sources, such as n...
Ancient lakes are among the best archivists of past environmental change, having experienced more than one full glacial cycle, a wide range of climatic conditions, tectonic events, and long association with human settlements. These lakes not only record long histories of environmental variation and human activity in their sediments, but also harbor...
In lakes that experience seasonal ice cover, understanding of nitrogen–oxygen coupling and nitrification has been dominated by observations during open water, ice-free conditions. To address knowledge gaps about nitrogen–oxygen linkages under ice, we examined long-term winter data (30 + years, 2–3 sample events per winter) in 7 temperate lakes of f...
The duration of winter ice cover on lakes varies substantially with climate variability, and has decreased over the last several decades in many temperate lakes. However, little is known of how changes in seasonal ice cover may affect biogeochemical processes under ice. We examined winter nitrogen (N) dynamics under ice using a 30+ yr dataset from...
Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer 'growing seasons'. We executed the first global quantitative synthesis on under-ice lake ecology, including...
Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer ‘growing seasons’. We executed the first global quantitative synthesis on under-ice lake ecology, including...
The essential role of phosphorus (P) for agriculture and its impact on water quality has received decades of research attention. However, the benefits of sustainable P use and management for society due to its downstream impacts on multiple ecosystem services are rarely acknowledged. We propose a conceptual framework—the "phosphorus-ecosystem servi...
Winter conditions are rapidly changing in temperate ecosystems, particularly for those that experience periods of snow and ice cover. Relatively little is known of winter ecology in these systems, due to a historical research focus on summer "growing seasons." We executed the first global quantitative synthesis on under-ice lake ecology, including...
Collectively, reservoirs created by dams are thought to be an important source of greenhouse gases (GHGs) to the atmosphere. So far, efforts to quantify, model, and manage these emissions have been limited by data availability and inconsistencies in methodological approach. Here, we synthesize reservoir CH 4 , CO 2 , and N 2 O emission data with th...
Reservoirs often receive excess nitrogen (N) and phosphorus (P) lost from agricultural land, and may subsequently influence N and P delivery to inland and coastal waters through internal processes such as nutrient burial, denitrification, and nutrient turnover. Currently there is a need to better understand how reservoirs affect nutrient transport...
Habitat fragmentation impedes dispersal of aquatic fauna, and barrier removal is increasingly used to increase stream network connectivity and facilitate fish dispersal. Improved understanding of fish community response to barrier removal is needed, especially in fragmented agricultural streams where numerous antiquated dams are likely destined for...
Recently, effects of lakes and reservoirs on river nutrient export have been incorporated into landscape biogeochemical models. Because annual export varies with precipitation, there is a need to examine the biogeochemical role of lakes and reservoirs over time frames that incorporate interannual variability in precipitation. We examined long-term...
1] Small impoundments intended for irrigation, livestock watering, and hydropower are numerous in agricultural regions of the world. Many of these artificial water bodies are well positioned to intercept fertilizer runoff and pollutants but could be vulnerable to long-term sedimentation, management intervention, or failure. We examined solute reten...
Some aquatic systems have disproportionately high nutrient processing rates, and may be important to nutrient retention within river networks. However, the contribution of such biogeochemical hot spots also depends on water residence time and hydrologic connections within the system. We examined the balance of these factors in a comparative study o...
Small impoundments are often crucial factors for the movement of
sediment, organic matter, water-borne nutrients, and toxic materials
through river networks. By recent accounting, at least 2.6 million small
artificial water bodies exist in the US alone. A large proportion of
those structures occur in regions with high intensity of agriculture,
such...
Summary1. Dissolved organic carbon (DOC) plays a central role in the dynamics of stream and river ecosystems, affecting processes such as metabolism, the balance between autotrophy and heterotrophy, acidity, nutrient uptake and bioavailability of toxic compounds. However, despite its importance to stream processes, restoration and management activi...
Background/Question/Methods
Ecosystem perturbations sometimes fit a classic disturbance-recovery trajectory, and at other times involve more persistent changes of state. We examined water chemistry responses to the transition of a flow-through wetland to more river-like conditions in agricultural southern Wisconsin, caused by phased removal of a...
An emerging issue in ecohydrology is the role of light in fluvial ecosystem dynamics. Here, we investigate how photosynthetically active radiation (PAR) influences the hydrogeomorphology and biogeochemistry of a second-order temperate stream with varying riparian communities from heavily shaded forest sections to unshaded grass sections. First, in-...
We reviewed the development of ideas and empirical understanding about disturbance in lotic ecosystems by providing a pre-1986 historic context and highlighting major themes that have emerged in the 25 y since the inception of J-NABS. Disturbance was not well incorporated into stream ecological thinking before 1986, but awareness of its significanc...
Steady-state approaches to the study of stream nutrient processing have several limitations. Dynamic (time series) approaches are more flexible, and allow interpretation of nutrient additions introduced as unsteady slugs (pulses). We compared soluble reactive phosphorus (SRP) uptake metrics from experimental nutrient pulses modeled dynamically with...
Optical water quality (OWQ) governs the quantity and quality of light in aquatic ecosystems, and thus spatiotemporal changes in OWQ affect many biotic and abiotic processes. Despite the fundamental role of light in rivers, studies on riverine OWQ have been limited and mostly descriptive. Here we provide a comprehensive, quantitative analysis of the...
Projects
Project (1)
Co-authors are Steve Powers and Xin Liu. . Here we explored the sensitivity of global phosphorus flows to interventions of the food system using a demand-driven substance flow model (SFM). The conservation interventions considered include: effect of population; reduction in animal fraction in the diet (AFD); animal manure use efficiency (MUE); agricultural phosphorus use efficiency (PUE); the fraction of food supply that is wasted (FWF); the fraction of food waste that is recycled to replace fertilizer (FRE); the fraction of human waste that is recycled to agricultural soil (WRE). The model shows that the animal fraction in the diet (AFD) is the most sensitive of these factors, and this factor interacts with PUE and MUE. Furthermore, there is a minimum AFD below which it actually becomes necessary to mine more phosphorus. Another significant result is that reducing food waste is about eighty times more effective than recycling food waste in reducing the demand for phosphate at the mine. Finally, the model was used to explore the global carrying capacity for humans, on the basis of P supply only. Current P system parameters and natural P sources may satisfy P requirements for as many as 2.5 billion people without any phosphate rock mining, and four to six times as many if significant improvements were made in all the considered interventions. Our analysis suggests priorities for adjusting human behaviors to achieve a more sustainable phosphorus future.
