GOALS SUMMARY
- Identify and map N hot spots in surface waters of the Great Bay Watershed
- Identify non-point sources of N that result in these hot spots
- Characterize the flow paths that deliver N to these hot spots
- Determine whether N removal occurs in vegetated riparian buffers with different land uses
- Quantify nitrate attenuation in tributary streams and the main stem
- Integrate these scientific investigations with stakeholders to ensure results are useful and accessible to environmental managers and other stakeholders
Objective 1: Identify and map “N hotspots” throughout the Great Bay watershed
Tasks
- Field sampling of extensive stream site. Stream samples analyzed for nutrient water chemistry.
- Synoptic stream water sampling of ~ 250 sites in major tributaries to tidal rivers (i.e., Lamprey, Oyster, and Bellamy).
- This “snapshot” approach of stream sampling during base flow conditions will be conducted periodically and results will be compared to sites within catchments with a range of land use characteristics (i.e., forested, agricultural, % impervious cover, human population density).
- Develop spatial map of N “hot spots”
- “Hotspots” may be defined as >100 people/km2 from each town or impervious > 10%. Hot spots will be predicted from existing models, and verified with field sampling. Models of N concentrations in sub-basins will be used to identify potential hot spots; the population density-nitrate model developed for the Lamprey River basin by the UNH Water Resources Research Center and the nitrogen loading model (NLM).
Objective 2: Identify NPS nitrogen– Intensive study
Tasks
- Target ~10 to 30 sites that have a range of nitrogen levels and land-use
- Seasonal analyses of N fractions in streams and shallow groundwater
- Water chemistry to identify sources of N
- Isotopic analysis of nitrate - δ15N and δ18O
- Distinguish between atmospheric, fertilizer and animal waste
- δ15N of organic matter, suspended sediment and surficial sediment
- Heavy δ15N indicates attenuation along flow path
- Detect for caffeine using HPLC as well as Boron isotopes using ICP-MS
- Indicates human waste stream, septic or sewer
- Optical brighteners using fluorescence spectroscopy; whitening agents in laundry detergents indicate septic or leaky sewers
- Microbiological source tracking to differentiate animal waste streams
- Test water for high fecal counts (>126 cfu/100ml)
- Use genotypic method: real-time PCR of mt (mitochondrial) DNA to confirm animal waste source (e.g. Human, Dog, Bovine, Geese) (Caldwell et al. 2009)
Objective 3: Identify N delivery pathways at intensive study sites
Tasks
- Characterize the hydrological flow path and nutrient chemistry using a multi-tracer approach (e.g., stable isotope, chemical, and microbial)
- Collect water samples from different points in the flowpath:
- Shallow (1-3 m depth) groundwater wells in the riparian flowpath
- Storm runoff collected from road culverts or swales emptying directly into intensive study streams
- Stream water
Objective 4: Examine extent of riparian denitrification with land-uses
Tasks
- Sample groundwater wells and streams for N removal
- Determine whether N removal occurs as water moves through the riparian zone
- Compare riparian removal in vegetated riparian buffers with different land uses
Objective 5: Examine in-stream nitrate attenuation – Intensive Sites
Tasks
- Determine N uptake in river reaches using mass balance for larger streams (4th-5th order)
- Use GIS and landscape models for upstream inputs and downstream output from river reach
- δ15N tracer experiments in smaller streams (1st-3rd order) to measure NO3 uptake
Objective 6: Integration of science with end users
- The various integration activities as described throughout this report continue to benefit the project direction and goals
- Assess the outreach and collaborative efforts and continue to initiate and host workshops with the community