Stephen Kalkhoff (Former Employee)
Science and Products
Filter Total Items: 70
Phosphorus in sediment in the Kent Park Lake watershed, Johnson County, Iowa, 2014–15 Phosphorus in sediment in the Kent Park Lake watershed, Johnson County, Iowa, 2014–15
Phosphorus data were collected from the Kent Park Lake watershed in Johnson County, Iowa, in 2014 and 2015 to obtain information to assist in the management of the water quality in the lake. Phosphorus concentrations were measured for sediment from several ponds in the watershed and sediment deposited in the lake. The first set of samples was collected in 2014 to understand phosphorus in...
Authors
Stephen J. Kalkhoff
Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds
Precipitation patterns and nutrient inputs affect transport of nitrate (NO3-N) and phosphorus (TP) from Midwest watersheds. Nutrient concentrations and yields from two subsurface-drained watersheds, the Little Cobb River (LCR) in southern Minnesota and the South Fork Iowa River (SFIR) in northern Iowa, were evaluated during 1996–2007 to document relative differences in timings and...
Authors
Stephen J. Kalkhoff, Laura E. Hubbard, Mark D. Tomer, D.E. James
Decadal surface water quality trends under variable climate, land use, and hydrogeochemical setting in Iowa, USA Decadal surface water quality trends under variable climate, land use, and hydrogeochemical setting in Iowa, USA
Understanding how nitrogen fluxes respond to changes in agriculture and climate is important for improving water quality. In the midwestern United States, expansion of corn cropping for ethanol production led to increasing N application rates in the 2000s during a period of extreme variability of annual precipitation. To examine the effects of these changes, surface water quality was...
Authors
Christopher T. Green, Barbara A. Bekins, Stephen J. Kalkhoff, Robert M. Hirsch, Lixia Liao, Kimberlee K. Barnes
Occurrence and transport of nutrients in the Missouri River Basin, April through September 2011 Occurrence and transport of nutrients in the Missouri River Basin, April through September 2011
Heavy snow and early spring rainfall generated substantial amounts of runoff and flooding in the upper part of the Missouri River Basin in 2011. Spring runoff in the upper and middle parts of the basin exceeded the storage capacity of the Missouri River reservoirs and unprecedented amounts of water were released into the lower parts of the basin resulting in record floods from June...
Authors
Stephen J. Kalkhoff
Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa
Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model...
Authors
Stephen J. Kalkhoff, Aldo V. Vecchia, Paul D. Capel, Michael T. Meyer
Environmental settings of the South Fork Iowa River basin, Iowa, and the Bogue Phalia basin, Mississippi, 2006-10 Environmental settings of the South Fork Iowa River basin, Iowa, and the Bogue Phalia basin, Mississippi, 2006-10
Studies of the transport and fate of agricultural chemicals in different environmental settings were conducted by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program's Agricultural Chemicals Team (ACT) at seven sites across the Nation, including the South Fork Iowa River basin in central Iowa and the Bogue Phalia basin in northwestern Mississippi. The...
Authors
Kathleen A. McCarthy, Claire E. Rose, Stephen J. Kalkhoff
Science and Products
Filter Total Items: 70
Phosphorus in sediment in the Kent Park Lake watershed, Johnson County, Iowa, 2014–15 Phosphorus in sediment in the Kent Park Lake watershed, Johnson County, Iowa, 2014–15
Phosphorus data were collected from the Kent Park Lake watershed in Johnson County, Iowa, in 2014 and 2015 to obtain information to assist in the management of the water quality in the lake. Phosphorus concentrations were measured for sediment from several ponds in the watershed and sediment deposited in the lake. The first set of samples was collected in 2014 to understand phosphorus in...
Authors
Stephen J. Kalkhoff
Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds Effect of variable annual precipitation and nutrient input on nitrogen and phosphorus transport from two Midwestern agricultural watersheds
Precipitation patterns and nutrient inputs affect transport of nitrate (NO3-N) and phosphorus (TP) from Midwest watersheds. Nutrient concentrations and yields from two subsurface-drained watersheds, the Little Cobb River (LCR) in southern Minnesota and the South Fork Iowa River (SFIR) in northern Iowa, were evaluated during 1996–2007 to document relative differences in timings and...
Authors
Stephen J. Kalkhoff, Laura E. Hubbard, Mark D. Tomer, D.E. James
Decadal surface water quality trends under variable climate, land use, and hydrogeochemical setting in Iowa, USA Decadal surface water quality trends under variable climate, land use, and hydrogeochemical setting in Iowa, USA
Understanding how nitrogen fluxes respond to changes in agriculture and climate is important for improving water quality. In the midwestern United States, expansion of corn cropping for ethanol production led to increasing N application rates in the 2000s during a period of extreme variability of annual precipitation. To examine the effects of these changes, surface water quality was...
Authors
Christopher T. Green, Barbara A. Bekins, Stephen J. Kalkhoff, Robert M. Hirsch, Lixia Liao, Kimberlee K. Barnes
Occurrence and transport of nutrients in the Missouri River Basin, April through September 2011 Occurrence and transport of nutrients in the Missouri River Basin, April through September 2011
Heavy snow and early spring rainfall generated substantial amounts of runoff and flooding in the upper part of the Missouri River Basin in 2011. Spring runoff in the upper and middle parts of the basin exceeded the storage capacity of the Missouri River reservoirs and unprecedented amounts of water were released into the lower parts of the basin resulting in record floods from June...
Authors
Stephen J. Kalkhoff
Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa Eleven-year trend in acetanilide pesticide degradates in the Iowa River, Iowa
Trends in concentration and loads of acetochlor, alachlor, and metolachlor and their ethanasulfonic (ESA) and oxanilic (OXA) acid degradates were studied from 1996 through 2006 in the main stem of the Iowa River, Iowa and in the South Fork Iowa River, a small tributary near the headwaters of the Iowa River. Concentration trends were determined using the parametric regression model...
Authors
Stephen J. Kalkhoff, Aldo V. Vecchia, Paul D. Capel, Michael T. Meyer
Environmental settings of the South Fork Iowa River basin, Iowa, and the Bogue Phalia basin, Mississippi, 2006-10 Environmental settings of the South Fork Iowa River basin, Iowa, and the Bogue Phalia basin, Mississippi, 2006-10
Studies of the transport and fate of agricultural chemicals in different environmental settings were conducted by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program's Agricultural Chemicals Team (ACT) at seven sites across the Nation, including the South Fork Iowa River basin in central Iowa and the Bogue Phalia basin in northwestern Mississippi. The...
Authors
Kathleen A. McCarthy, Claire E. Rose, Stephen J. Kalkhoff