ARSH AGARWAL, ALLISON BRADFORD, KERRY CHENG, RAMITA DEWAN,
ENRIQUE DISLA, ADDISON GOODLEY, NATHAN LIM, LISA LIU, LUCAS PLACE,
RAEVATHI RAMADORAI, JAISHRI SHANKAR, MICHAEL WELLEN, DIANE YE,
EDWARD YU MENTOR: DR. DAVE TILLEY LIBRARIAN: ROBERT KACKLEY
GEMSTONE PROGRAM 03/18/2011 SWAMP Superior Wetlands Against
Malicious Pollutants
Slide 2
Research Problem Agricultural runoff, especially in the spring,
leads to high nitrate levels in the Chesapeake Bay Watershed Causes
harmful algal blooms Result: Dead zones due to depletion of oxygen
and nutrients vital to aquatic wildlife Dead zone: low oxygen area
of water
Slide 3
Research Problem Significance of Project Affects fishing
industry, seafood consumers, environmental groups, residents of the
Chesapeake Bay Watershed Health of the Chesapeake Bay is vital for
maintaining biodiversity
Slide 4
Overview of Project Goal: to build a wetland that optimally
removes nitrates from the Chesapeake Bay and its surrounding waters
How? With a constructed wetland! Mostly greenhouse-based experiment
in 3 phases Emulate conditions of the Tuckahoe Creek within the
greenhouse Questions to answer through literature: Where does the
agricultural runoff come from? What plants can we use to remove the
nitrates? Can we affect the rate of nitrate removal? How? With
what?
Slide 5
Literature Review Agricultural Runoff One of the largest
sources of pollution into the Bay Main sources: fertilizer and
manure Plants only absorb up to 18% of nitrogen from fertilizer Up
to 35% of nitrogen fertilizer washes into coastal waters and their
surrounding bodies of water Nitrates come mostly from chicken
manure in agricultural runoff Eutrophication causes harmful algal
blooms Eutrophication: steep increase in nutrient concentration in
neighboring bodies of water Algal blooms lead to dead zones
Constructed wetlands Can remove up to 80% of inflowing
nitrates
Slide 6
Literature Review River Selection Big picture: Chesapeake Bay
Not ideal for accessibility, too large a body of water for us to
study in such a short time Choptank River largest eastern tributary
of the Bay 70% of nitrogen input is from agricultural runoff Still
not very accessible for a large group of students with limited
funds and transportation Tuckahoe Creek Tuckahoe sub-basin
represents 34% of Choptank Watershed More accessible for our
team
Slide 7
The Nitrogen Cycle Image from: www.fao.org
Slide 8
Literature Review Plant Selection Criteria for plant selection
Non-invasive Native to the Chesapeake Bay Watershed
Biofuel-capable
Slide 9
Literature Review Plant Selection Cattail (Typha latifolia)
Very commonly researched wetland plant Especially viable as a
biofuel Soft-stem Bulrush (Schoenoplectus validus) More effective
at denitrification than other comparable plant species. Study:
Schoenoplectus is responsible for 90% of all nitrate removal in
experimental treatments Switchgrass (Panicum virgatum) One of the
most common, effective nitrate-removing plants in the Chesapeake
Bay area
Slide 10
Literature Review Biofuels Why biofuels? To accommodate
changing energy and environmental needs Secondary data analysis
Cattail Potential ethanol source Can be harvested for cellulose
Switchgrass One hectare plot of switchgrass yielded up to 21.0 dry
megagrams of biomass Soft-stem bulrush In one study, out of 20
wetland species, soft-stem bulrush ranked second in energy output
per unit mass Cross-referenced list of Chesapeake Bay native,
non-invasive plants with list of biofuel-capable plants Selected
plants seemed to be the best options for research
Slide 11
Literature Review Organic Factors Why? Increase statistical
significance of differences in nitrate removal Three carbon-based
factors Glucose Increases nitrate removal rates in artificial
wetlands Sawdust Study compared glucose & sawdust glucose
ranked first, sawdust ranked second Wheat straw Increases nitrate
removal rate for 7 days, then decreases in effectiveness
Slide 12
Methodology Experimental Design & Setup Take several
samples at Tuckahoe Creek Mostly in spring highest nitrate
concentration Use highest value of collected samples in greenhouse
environment Samples include water and soil Soil samples are
necessary to inoculate the greenhouse soil Inoculating soil will
allow Tuckahoe-native bacteria to grow in our greenhouse
environment Extraneous variables? Realistically, we cannot emulate
all elements of the Tuckahoe Creek in the greenhouse. Nitrate
concentration, soil composition, & temperature are three
elements that we can realistically control
Slide 13
Methodology Experimental Design & Setup (Phase 1) Goal:
find most effective organic factor Use single plant species
(cattail) In each microcosm, place one or a combination of organic
factors Each microcosm will contain potting soil, top soil, soil
from the Tuckahoe Creek (for inoculation), and the experimental
variable Inoculating greenhouse soil with Tuckahoe soil will allow
Tuckahoe-native bacteria to grow in our greenhouse environment
Collect effluent from each microcosm and pour it back over the
microcosm once a day for 7 days Measure nitrate concentration of
the effluent at the end of the week. Determine which factor or
combination of factors per experimental unit most effectively
increases nitrate uptake Experimental unit is one bucket
Slide 14
Methodology Example Diagram of Setup for Phase 1 Note: Phase 2
will look similar, but with different combinations in each bucket
the combinations will be of different plants, same organic
factor
Slide 15
Methodology Experimental Design & Setup (Phase 2) Goal:
find most effective plant or combination of plants using the
organic factor determined in phase 1 Use multiple plant species
Place each combination in a microcosm Each microcosm will contain
potting soil, top soil, soil from the Tuckahoe Creek (for
inoculation), and the experimental variable Collect effluent from
each microcosm and pour back over the microcosm once a day for 7
days Standard water analysis will determine water quality Determine
which plant or plants (experimental unit) most effectively removes
nitrates from water Experimental unit is one bucket
Slide 16
Methodology Experimental Design & Setup (Phase 3) Goal:
apply the results of Phases 1 & 2 to a larger, more
wetland-like setting Use the best factor and best combinations of
plants Place them in a larger setting (i.e. a mini constructed
wetland within the greenhouse) Run experiment for 7 days, flowing
water through this larger- scale wetland environment Measure
effluent once a day for 7 days to determine nitrate removal
efficiency Pending results of 1&2 depends on time
Slide 17
Methodology Data Collection Data Collection Effluent collected
every day for 7 day trial Standard water analysis Includes our
variables, plus other details about water quality Mostly within
greenhouse Some data collection in the field (Tuckahoe) for samples
and testing of environment Six 1-week long trials 7 replicates of
each microcosm per trial Total of 42 data points (can assume normal
distribution)
Slide 18
Methodology - Data Analysis Data Analysis Phase 1: Two-factor
ANOVA 2 levels 4 treatments Phase 2: Single factor ANOVA, Tukeys
Studentized Range 1 level 8 treatments Statistical Analysis
Software (SAS) to perform calculations
Slide 19
Current Progress Finishing experimental setup and design
Ironing out the fine details of water collection/measurement/etc
Applying for grants Bill James, ACCIAC, Library (submitted), Sea
Grant, HHMI Ongoing literature review Tuckahoe Creek visits Soil
samples: early March Water samples: late April/early May This is
when nitrate concentration is highest Greenhouse space Guaranteed
space in the UMD greenhouse until May 2012
Slide 20
References Anderson, D., & Glibert, P., & Burkholder J.
(2002). Harmful algal blooms and eutrophication: Nutrient sources,
composition, and consequences. Coastal and Estuarine Research
Federation, 24(4), 704-726. Burgin, A., Groffman, P., & Lewis,
D. (2010). Factors regulating denitrification in a riparian
wetland. Soil Sci. Soc. Am. J., 74(5), 1826-1833. doi:
10.2136/sssaj2009.0463 Fraser, L. H., Carty, S. M., & Steer, D.
(2004). A test of four plant species to reduce total nitrogen and
total phosphorus from soil leachate in subsurface wetland
microcosms. Bioresource Technology, 94(2), 185-192. Hien, T.
(2010). Influence of different substrates in wetland soils on
denitrification. Water, Air, and Soil Pollution, June 2010, 1-12.
doi:10.1007/s11270-010-0498-6 Gray, K. & Serivedhin, T. (2006).
Factors affecting denitrification rates in experimental wetlands:
Field and laboratory studies. Ecological Engineering, 26, 167-181.
Ines, M., Soares, M., & Abeliovich, A. (1998). Wheat straw as
substrate for water denitrification. Water Research. 32(12),
3790-3794. Karrh, R., Romano, W., Raves-Golden, R., Tango, P.,
Garrison, S., Michael, B., Karrh, L. (2007). Maryland tributary
strategy Choptank River basin summary report for 1985-2005 Data.
Annapolis, MD: Maryland Department of Natural Resources. Rogers,
K., Breen, P., & Chick, A. (1991). Nitrogen removal in
experimental wetland treatment systems: Evidence for the role of
aquatic plants. Research Journal of the Water Pollution Control
Federation, 63(7), 9. Staver, L. W., Staver, K. W., &
Stevenson, J. C. (1996). Nutrient inputs to the Choptank river
estuary: Implications for watershed management. Estuaries, 19(2),
342-358. Wright, L., & Turhollow, A. (2010). Switchgrass
selection as a model bioenergy crop: A history of the process.
Biomass and Bioenergy, 34(6), 851-868.
doi:10.1016/j.biombioe.2010.01.030 Zedler, J. B. (2003). Wetlands
at your service: reducing impacts of agriculture at the watershed
scale. Frontiers in Ecology and the Environment, 1(2), 65-72.
Zhang, B., Shahbazi, A., Wang, L., Diallo, O., & Whitmore, A.
(2010). Hot-water pretreatment of cattails for extraction of
cellulose. Journal of Industrial Microbiology & Biotechnology,
1-6. doi: 10.1007/s10295-010-0847-x
Slide 21
Thank you! Many thanks to... Dr. Dave Tilley Dr. Bruce James
Brandon Winfrey Dr. Wallace Dr. Thomas Courtenay Barrett Gemstone
Program & Staff Robert Kackley