County-level estimates of nutrient inputs to the land surface of the conterminous United States, 1982-2001

Ruddy, Barbara C.; Lorenz, David L.; Mueller, David K.

doi:10.3133/sir20065012

Cited by 158 publications

(200 citation statements)

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“…Simple calculation of phosphorus loading from the given 553 million tons of annual sediment loading (assuming a phosphorus concentration of 600 mg/kg) yields 332 thousand tons/yr, falling between forest and range contributions. More recent estimates of nationwide agricultural phosphorus loading are much higher, 3,539 and 3,201 thousand tons/yr for 1997 and 1987, respectively (Ruddy et al, 2006). Our median estimates are approximately 25% of these values; again suggesting that phosphorus loading from bank erosion can be significant compared to more traditionally recognized sources.…”

Section: Comparison With Field Datasupporting

confidence: 49%

Uncertainty and sensitivity in a bank stability model: implications for estimating phosphorus loading

Lammers

Bledsoe

Langendoen

2016

Earth Surf Processes Landf

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UNCERTAINTY AND SENSITIVITY IN A BANK STABILITY MODEL: IMPLICATIONS FOR ESTIMATING PHOSPHORUS LOADINGEutrophication of aquatic ecosystems is one of the most pressing water quality concerns in the U.S. and around the world. Bank erosion has been largely overlooked as a source of nutrient loading, despite field studies demonstrating that this source can account for the majority of the total phosphorus budget of a watershed. Substantial effort has been made to develop mechanistic models to predict bank erosion and instability in stream systems; however, these models do not account for inherent natural variability in input values. Providing only single output values with no quantification of associated uncertainty can complicate management decisions focused on reducing bank erosion and nutrient loading to streams. To address this issue, uncertainty and sensitivity analyses were performed on the Bank Stability and Toe Erosion Model (BSTEM), a mechanistic model developed by the USDA-ARS that simulates both mass wasting (stability) and fluvial erosion of streambanks. Sensitivity analysis results indicate that variable influence on model output can vary depending on assumed input distributions.Generally, bank height, soil cohesion, and plant species were found to be most influential in determining stability of clay (cohesive) banks. In addition to these three inputs, groundwater elevation, stream stage, and bank angle were also identified as important in sand (non-cohesive) banks. Slope and bank height are the dominant variables in fluvial erosion modeling, while erodibility and critical shear stress are relatively unimportant. However, the threshold effect of critical shear stress (determining whether erosion occurs) was not explicitly accounted for, ii possibly explaining the relatively low sensitivity indices for this variable. Model output distributions of sediment and phosphorus loading rates corresponded well to ranges published in the literature, helping validate both model performance and selected ranges of input values. In addition, a probabilistic modeling approach was applied to data from a watershed-scale sediment and phosphorus loading study on the Missisquoi River, Vermont to quantify uncertainty associated with these published results. While our estimates indicated that bank erosion was likely a significant source of sediment and phosphorus to the watershed in question, the uncertainty associated with these predictions indicates that they should probably be considered order of magnitude estimates only.iii ACKNOWLEDGEMENTS

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Section: Comparison With Field Datasupporting

confidence: 49%

Uncertainty and sensitivity in a bank stability model: implications for estimating phosphorus loading

Lammers

Bledsoe

Langendoen

2016

Earth Surf Processes Landf

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“…Trends from 1993 to 2003, however, will not reflect the widespread increase in stream nutrient concentrations that occurred over the last century (15), when nutrient inputs to streams from fertilizer, industrial emissions, and other anthropogenic sources increased substantially (16,17). Instead, trends from 1993 to 2003 will reflect more recent changes, including management strategies designed to reverse or reduce the pace of earlier increases.…”

Section: Methodsmentioning

confidence: 99%

“…Nitrogen in atmospheric deposition was derived from wet deposition data from the National Atmospheric Deposition Program (16). Phosphorus and nitrogen inputs from fertilizer (including farm and nonfarm uses) were derived from sales and expenditures data from the Association of American Plant Food Control Officials and the U.S. Census of Agriculture (14,16).…”

Section: Methodsmentioning

confidence: 99%

“…Phosphorus and nitrogen inputs from fertilizer (including farm and nonfarm uses) were derived from sales and expenditures data from the Association of American Plant Food Control Officials and the U.S. Census of Agriculture (14,16). Phosphorus and nitrogen inputs from manure (including confined and unconfined livestock) were derived from livestock population data from the U.S. Census of Agriculture (16). Population density was derived from census block groups and population counts from the U.S. Census of Population and Housing (24,25).…”

Section: Methodsmentioning

confidence: 99%

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Regional Nutrient Trends in Streams and Rivers of the United States, 1993−2003

Sprague

Lorenz

2009

Environ. Sci. Technol.

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Trends in flow-adjusted concentrations (indicators of anthropogenic changes) and observed concentrations (indicators of natural and anthropogenic changes) of total phosphorus and total nitrogen from 1993 to 2003 were evaluated in the eastern, central, and western United States by adapting the Regional Kendall trend test to account for seasonality and spatial correlation. The only significant regional trend was an increase in flow-adjusted concentrations of total phosphorus in the central United States, which corresponded to increases in phosphorus inputs from fertilizer in the region, particularly west of the Mississippi River. A similar upward regional trend in observed total phosphorus concentrations in the central United States was not found, likely because precipitation and runoff decreased during drought conditions in the region, offsetting the increased source loading on the land surface. A greater number of regional trends would have been significant if spatial correlation had been disregarded, indicating the importance of spatial correlation modifications in regional trend assessments when sites are not spatially independent.

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“…Sites were selected within each study area to maximize the gradient of nutrient conditions while minimizing other natural or anthropogenic (Ruddy et al 2006), and measured nutrient concentrations, habitat, and stream size. This resulted in 33 streams being selected across the four agricultural study areas.…”

Section: Site Selectionmentioning

confidence: 99%

The relative influence of nutrients and habitat on stream metabolism in agricultural streams

Frankforter

Weyers

Bales

et al. 2009

Environ Monit Assess

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Stream metabolism was measured in 33 streams across a gradient of nutrient concentrations in four agricultural areas of the USA to determine the relative influence of nutrient concentrations and habitat on primary production (GPP) and respiration reach. When data for all study areas were combined, there were no statistically significant relations between gross primary production or community respiration and any of the independent variables. However, significant regression models were developed for three study areas for GPP (r 2 = 0.79-0.91) and CR-24 (r 2 = 0.76-0.77). Various forms of nutrients (total phosphorus and area-weighted total nitrogen loading) were significant for predicting GPP in two study areas, with habitat variables important in seven significant models. Important physical variables included light availability, precipitation, basin area, and in-stream habitat cover. Both benthic and seston chlorophyll were not found to be important explanatory variables in any of the models; however, benthic ash-free dry weight was important in two models for GPP.

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County-level estimates of nutrient inputs to the land surface of the conterminous United States, 1982-2001

Cited by 158 publications

References 0 publications

Uncertainty and sensitivity in a bank stability model: implications for estimating phosphorus loading

Uncertainty and sensitivity in a bank stability model: implications for estimating phosphorus loading

Regional Nutrient Trends in Streams and Rivers of the United States, 1993−2003

The relative influence of nutrients and habitat on stream metabolism in agricultural streams

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