Net anthropogenic phosphorus inputs: spatial and temporal variability in the Chesapeake Bay region (original) (raw)
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Phosphorus and the Chesapeake Bay: Lingering Issues and Emerging Concerns for Agriculture
Journal of Environmental Quality, 2019
Hennig Brandt's discovery of phosphorus (P) occurred during the early European colonization of the Chesapeake Bay region. Today, P, an essential nutrient on land and water alike, is one of the principal threats to the health of the bay. Despite widespread implementation of best management practices across the Chesapeake Bay watershed following the implementation in 2010 of a total maximum daily load (TMDL) to improve the health of the bay, P load reductions across the bay's 166,000‐km2 watershed have been uneven, and dissolved P loads have increased in a number of the bay's tributaries. As the midpoint of the 15‐yr TMDL process has now passed, some of the more stubborn sources of P must now be tackled. For nonpoint agricultural sources, strategies that not only address particulate P but also mitigate dissolved P losses are essential. Lingering concerns include legacy P stored in soils and reservoir sediments, mitigation of P in artificial drainage and stormwater from hot...
Water, Air, and Soil Pollution, 2005
This paper compares phosphorus (P) concentrations in sediments from two watersheds, one with, and one without, intensive animal agriculture. The watersheds are in the coastal plain of the Chesapeake Bay and have similar physiographic characteristics. Agriculture in the Pocomoke River, MD, watershed supplied 2.7 percent of all broiler chickens produced in the USA in 1997. Poultry litter is an abundant, local source of manure for crops. Broiler chickens are not produced in the Popes Creek, VA, watershed and poultry manure is, therefore, not a major source of fertilizer. The largest concentrations of P in sediment samples are found in floodplain and main-stem bottom sediment in both watersheds. Concentrations of total P and P extracted with 1N HCl are significantly larger in main-stem bottom sediments from the Pocomoke River than in main-stem bottom sediments from Popes Creek. Larger concentrations of P are associated with what are potentially redox sensitive iron oxyhydroxides in sediment samples from the Pocomoke River watershed than are associated with what are potentially redox sensitive iron oxyhydroxides in sediment samples from the Popes Creek watershed. Data for P and iron (Fe) concentrations in sediments from the Popes Creek watershed provide a numerical framework (baseline) with which to compare P and Fe concentrations in sediment from the Pocomoke River watershed.
Phosphorus export across an urban to rural gradient in the Chesapeake Bay watershed
Journal of Geophysical Research: Biogeosciences, 2012
Watershed export of phosphorus (P) from anthropogenic sources has contributed to eutrophication in freshwater and coastal ecosystems. We explore impacts of watershed urbanization on the magnitude and export flow distribution of P along an urban-rural gradient in eight watersheds monitored as part of the Baltimore Ecosystem Study Long-Term Ecological Research site. Exports of soluble reactive phosphorus (SRP) and total P (TP) were lowest in small watersheds with forest and low-density residential land use (2.8-3.1 kg À1 km À2 yr À1). In contrast, SRP and TP exports increased with watershed impervious surface coverage and reached highest values in a small urban watershed (24.5-83.7 kg À1 km À2 yr À1). Along the Gwynns Falls, a larger watershed with mixed land use, the greatest proportion of SRP (68%) and TP (75%) was contributed from the lower watershed, where urban areas were the dominant land use. Load duration curve analysis showed that increasing urbanization in watersheds was associated with shifts in P export to high-flow conditions (>2 mm d À1). SRP concentrations during low-flow conditions at urban headwater sites were highest during summer and lowest during winter. This seasonal pattern was consistent with sediment incubation experiments showing that SRP release from sediments was temperature dependent. Our results suggest that shifts in streamflow and alterations in water temperatures owing to urbanization and climate can influence stream water P concentrations and P export from urban watersheds.
Digital data used to relate nutrient inputs to water quality in the Chesapeake Bay watershed
Open-File Report, 1999
Introduction Purpose and scope Acknowledgments Data sets Water-quality data Segmented-watershed network Nutrient-input sources Atmospheric deposition Septic systems Point sources Land use and land cover Agricultural sources Land-surface characteristics Precipitation Temperature Slope Soil permeability Hydrogeomorphic regions Nutrient yield estimates Summary Selected References Appendix Metadata for data sets FIGURES Maps showing: 1. The Chesapeake Bay watershed and surrounding area 2. Streamflow data-collection sites used to estimate stream-nutrient loads in the Chesapeake Bay watershed, 1992 3. A segmented-watershed network used in the Chesapeake Bay watershed, 1992 4. Atmospheric deposition in the Chesapeake Bay region, 1992 5. Loads of nitrogen from septic systems in the Chesapeake Bay watershed, 1990 8 6. Average-annual loads of nitrogen and phosphorus from point-source discharge in the Chesapeake Bay watershed, 1992 7. Land use and land cover in the Chesapeake Bay watershed modified from Multi Resolution Land Characterization (MRLC), 1992 8. Land use and land cover in the Chesapeake Bay watershed modified from the Chesapeake Bay Program 10 9. Loads of nitrogen from manure and commercial fertilizer applied to agricultural land in the Chesapeake Bay watershed, 1992 10. Loads of phosphorus from manure and commercial fertilizer applied to agricultural land in the Chesapeake Bay watershed, 1992 11. Average-annual precipitation in the Chesapeake Bay region v 12. Average-annual temperature in the Chesapeake Bay region 12 13. Slope shown as percentages in the Chesapeake Bay region 14. Soil permeability in the Chesapeake Bay watershed 13 15. Hydrogeomorphic regions in the Chesapeake Bay watershed 13 16. Incremental yields of total nitrogen and total phosphorus from all sources in the Chesapeake Bay Watershed, 1992 13 17. Delivered yields of total nitrogen and total phosphorus from all sources in the Chesapeake Bay Watershed, 1992 13 18. Total yields of total nitrogen and total phosphorus from all sources in the Chesapeake Bay Watershed, 1992 13
Water Quality Trends Following Anomalous Phosphorus Inputs to Grand Bay, Mississippi, USA
Gulf and Caribbean Research, 2018
IntroductIon Grand Bay National Estuarine Research Reserve (GB-NERR) is nitrogen-limited (Blackburn 2000, Amacker 2013, Baine 2017) and adjacent to a phosphate fertilizer production facility (Mississippi Phosphates Corporation, MPC, Figure 1). The MPC produced diammonium phosphate (DAP) fertilizer from the 1960s until late 2014. Calcium sulfate, or phosphogypsum, a byproduct of this process, was stored in large stacks as waste. Phosphogypsum is rich in phosphorus, highly acidic (pH ~2 .4), and contains several impurities such as radionuclides, heavy metals, fluoride, and sulfide (
Spatial and temporal variability in excessive soil phosphorus levels in eastern North Carolina
Nutrient Cycling in Agroecosystems - NUTR CYCL AGROECOSYST, 2004
Numerous studies have shown that accumulation of excessive soil phosphorus raises the potential for phosphorus export and eutrophication of adjacent surface waters. Soil phosphorus data from the North Carolina Agronomy Division's database were analyzed for two-year periods spanning the decades of the 1980s and 1990s for 39 eastern North Carolina counties. Eastern North Carolina supported extensive row crop agriculture, rapidly growing intensive livestock industries, and a growing human population during these decades. Excessive soil phosphorus levels, defined as having a soil phosphorus index (P-I, based on Mehlich III testing) > 100, occurred in over 40% of almost a million samples reported for the three two-year periods analyzed. Excessive soil P-I levels were most frequent in central eastern North Carolina, declined in the 1980s and rose again in the 1990s. The distribution of row crop area with excessive soil P-I levels was very similar in time and space. Increases in th...
Effects of Agriculture on Discharges of Nutrients from Coastal Plain Watersheds of Chesapeake Bay
Journal of Environmental Quality, 1997
We measured annual discharges of water, sediments, and nutrients from 17 Chesapeake Bay watersheds with differing proportions of agricultural lands on the inner, central, and outer Coastal Plain. In all regions of the Coastal Plain, the flow-weighted mean concentrations of N species in watershed discharge increased as the proportion of cropland in the watershed increased. In contrast, the concentrations of P species did not correlate with any land use. Instead, P concentrations correlated with the concentration of suspended particles, which differed greatly among watersheds in different regions of the Coastal Plain. Consequently, the ratio of NIP in discharges differed widely among watersheds, potentially affecting N or P limitation of phytoplankton growth in the receiving waters. Concentrations of dissolved silicate, organic C, pH, and alkalinity in discharges did not differ greatly among watersheds or correlate with land use. Nitrogen discharge correlated with net anthropogenic inputs of N to the watershed, but usually less than one-third of the net anthropogenic inputs were discharged. GRICULTURAL activities can increase fluvial dis-A charges of nutrients, but the magnitude of the effect of agriculture is difficult to predict. Watersheds with greater proportions of agricultural land have been found to discharge greater amounts of N (