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Solutions to Nitrogen Pollution: Solving the Cranberry Puzzle
- The study measured nitrogen and phosphorus concentrations and estimated water flows in and out of two common types of cranberry bogs over two growing seasons to calculate nutrient fluxes. - Results found variable concentrations that made defining averages difficult, but fluxes were in the range of previous studies. Phosphorus tended to be highest in outflow during harvest floods. - Scaling bog fluxes to the whole watershed led to similar conclusions as other studies about the proportion of nitrogen coming from bogs. Future work should better quantify water flows and increase sampling frequency. - Other related research includes continuous monitoring of multiple bogs to better understand nutrients in floods and storms. This will provide improved data for watershed models.
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Solutions to Nitrogen Pollution: Solving the Cranberry Puzzle
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- 2. Logistics and Details • Agenda • Evaluation –please fill out and return. • Upcoming workshops – May 27 – Solutions to Nitrogen Pollution: The Wareham Case Study. – June 11 – Water Words that Work. • www.savebuzzardsbay.org/DecisionMakers
- 3. Outline • Rachel – Background & study methodology •Chris – Study results • Carolyn – Other research & next steps • Kirby – Perspective from a grower
- 4. What is Nitrogen Pollution? • Nitrogen is a naturally occurring element • Nitrogen is a key component of cellular building blocks •Nitrogen usually controls how much algae grow in coastal waters • Too much nitrogen is damaging to coastal ecosystems
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- 8. Nitrogen pollution management • Many coastal waters around Buzzards Bay are listed as impaired for N on 303(d) ‘Dirty Waters’ list • MA is required to developed TMDLs for these waters that include plans for reducing N •Massachusetts Estuaries Project develops a target N threshold that a specific estuary can handle and sources of N to that estuary • Local Management is critical
- 9. Wareham Nitrogen Consensus • Collaboration of Wareham thought leaders who all believed they had a direct interest in seeing N pollution reduced and Wareham coastal water quality restored • Series of nine facilitated meetings focusing on two N pollution sources: wastewater and cranberry agriculture •Group collaboratively developed an Action Plan • One action was to launch a scientific study to better determine N loadings from different types of cranberry bogs
- 10. Agriculture as a nitrogen source • Agriculture can be a significant contributor to N in coastal waters in SE MA, though wastewater is typically the largest source of N • Cranberry is the dominant form of agriculture in the Buzzards Bay watershed •While a low relative rate of fertilizer compared with other crops they are closely connected to waterways
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- 12. Distribution of N sources • In some SE MA subwatersheds cranberry agriculture can be a significant contributor of N to coastal waters Agawam River subwatershedWankinko River subwatershed Data from Massachusetts Estuaries Project (Howes et al. 2013)
- 13. Understanding the effect of bogs • Limited quantitative information – only two scientific studies in SE MA on N loss from bogs •Values from the two studies range by over 3‐fold for N loading • Uncertainty in loading models can lead to unfulfilled or unexpected outcomes from actions taken • Biggest concern is movement of N in surface water • Extent of groundwater pathway is unknown
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- 15. Basic study design • Measure N & P in water before and after it is on the bog • Groundwater up and down gradient •Surface water in and out • Measure surface water levels to estimate flow • Combine N & P concentration data with water flow estimates to calculate mass of N & P leaving the bogs
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- 26. Nitrogen fluxes to the Wareham River Estuary Fluxes in perspective Assumptions: Watershed fluxes: DeMoranville & Howes 17% from bogs This study19‐22% from bogs • Annual fluxes in current study are in the same proportion to harvest floods as in DeMoranville & Howes • Same proportion of flow‐through and more modern bogs as in MEP • Same attenuation (8‐17%) in streams and rivers
- 27. • Concentrations and forms of nitrogen and phosphorus in input and output water were variable and made it hard to define an "average" bog • Phosphorus concentrations tended to be highest in outflowing water during harvest floods •Net nutrient fluxes based on estimates of water flow and measured input and output concentrations were in the range measured by other studies and provide confidence that we correctly estimated the range of potential fluxes • Scaling fluxes from cranberry bogs to the whole watershed leads to conclusions similar to those reached in the MEP • Future work should better quantify water fluxes and increase sampling frequency to better capture changes to concentrations during periods of high water movement. Conclusions
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- 29. • Casey Kennedy, USDA ARS – Continuous monitoring approach –Multiple sites – P and N • Coalition / MBL / Cranberry Station group – Lessons from Kennedy outcomes – Continuous approach to floods and storm events UMass Cranberry Station Research Projects
- 30. UMass Cranberry Station Casey Kennedy –Several ongoing studies
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- 33. Kennedy studies – P in floods • Winter flood is 4x lower in P compared to harvest •Newly renovated bogs export less P in floods • TDP – mainly from soil pore water • TPP – ditch sediment mobilization UMass Cranberry Station Kennedy studies – P in floods
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- 37. UMass Cranberry Station Kennedy studies –N in floods TN rise associated with drainage reaching 50 cm below the surface – combination of pore water and ditch sediments Ditch water Flood release water Water level 50 cm below surface
- 38. UMass Cranberry Station “Wisconsin Style” Bog –yearly study TD3TD4 TD2 TD1 FLUME ‐Cranberry Bed ‐Drainage Ditch ‐Sampling site ‐Discharge Flume ‐Input Flume ‐Flow Direc on of ditch ‐Drainage le
- 39. UMass Cranberry Station Hydrologic Inputs 1.48 4.10 6.50 1.17 irrigation precip floodinput Input from adjacent bed
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- 43. UMass Cranberry Station Net Export of Storms and Flood 2.414 2.932 TDN(kg) Total Storms Harvest Flood 0.985 2.750 DON (kg) Total Storms Harvest Flood
- 44. UMass Cranberry Station The future •Partner group – Will continue study of sites, funding from the EPA via Coastal Zone Management – Methods modified to more continuous approach: lessons from other projects – Focus on floods AND big rain events – Develop better numbers for the Mass Estuaries model based on bog configurations
- 45. UMass Cranberry Station The future •Kennedy – Annual nutrient budgets – but….. – Models • Hydrogeology • Placement in landscape
- 46. UMass Cranberry Station The future •Cranberry Station In addition to research: – Use research to formulate extension recommendations – Example: Focus on critical portions of events
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