Post on 14-Aug-2020
Phytoremediation of Excessive Nutrients in Surface Water
• Introduction to Major Causes + Concerns
• Current Methods to Address Contamination
• Research Methodology
• Benefits + Challenges
• Conclusion
Main Sources of Excess Nutrients Nitrogen N, Nitrate NO3 Ammonium NH4
+ • Non-Point sources
» Decentralized treatment of human waste » Over Application of nitrogen fertilizers » Combustion of Fossil Fuels (airborne)
• Point Sources » Concentrated Animal Feeding Operations (CAFO’s) » Poorly or untreated human waste » In the manufacture of fibers, plastics, explosives, paper, and
rubber. » It is used as a coolant, in metal processing, » Used in cleansing agents and as food additives
Phosphorus P, Phosphate PO43-
• Point and Non point sources » Mining » Fertilizer » Yard Clippings » Soil Erosion » Septic and Animal Waste » Some cleaning agents
EUTROPHICATION is a complex process which occurs both in fresh and marine waters, where excessive development of certain types of phytoplankton and cyanobacteria such as blue green algae chokes out light and oxygen in aquatic ecosystems and becomes a threat for animal and human health.
THE PRIMARY CAUSES Are non point source runoff of excessive concentrations of plant nutrients originating from fertilizers, the burning of fossil fuels and sewage treatment.
-World Health Organization
http://oceanservice.noaa.gov/products/pubs_hypox.html
Source: http://earthobservatory.nasa.gov
400 Systems 245,000 Square Kilometers
The formation of dead zones and consequent worldwide coastal eutrophication are fueled by runoff of fertilizers and burning of fossil fuels
Resulting in an accumulation of particulate organic matter which encourages microbial activity and the consumption of dissolved oxygen in bottom waters
Dianchi Lake, Largest Lake in Yunnan Provence, China
Tampa Bay, Florida
Western Lake Erie Basin, Detroit Michigan
Human Health Risks In addition to the environmental hazard of eutrophication in ground and surface water, nitrates and phosphates can have severe direct effects on human health via untreated drinking water
Nitrates NO3 and Nitrites NO2− (Volatized Ammonium)
Methemoglobinemia in Infants
Phosphate PO43-
Naturally Radioactive Cumulative exposure considered dangerous but is not well understood.
Eichhornia crassipes WATER HYACINTH
PROS CAN DOUBLE IN NUMBER AND BIOMASS IN 6-15 DAYS
HIGH NUTRIENT UPTAKE AND BIOMASS YEILD > WATER LETTUCE
CONS HIGHLY INVASIVE
NOT WELL SUITED TO SALINE WATERS
Pistia stratiotes WATER LETTUCE
PROS HIGH NUTRIENT UPTAKE AND BIOMASS YEILD
BETTER SUITED TO SALINE WATERS
CONS HIGHLY INVASIVE
SEASONALLY DEPENDANT BIOMASS YEILD
REQUIRES EXTREMELY HIGH AMOUNTS OF NUTRIENTS
TEMPERATURE IS A LIMITING FACTOR
The Experiment
Study Area St. Lucie Estuary Watershed, Florida
• Indian River Lagoon BMP called For:
A reduction of N and P of 30 to 70 % called for by Surface Water Improvement and Management Plan (SWIM)
Public outreach has only met 10-15% of BMP prescription
images: Indian River Lagoon Species Inventory http://www.sms.si.edu/irlspec/index.htm
Quin Lu Zhenli L. He Donald A Graetz Peter J. Stoffella Xiaoe Yang
Indian River Research and Education Center, University of Florida Soil and Water Science Dept
Ministry of Ed. Key Lab of Environmental Remediation and Ecological Health in Hangzhou China
• Funded in Part by a Grant from South Florida Water mgmt District
Study Authors
Materials and Methods
• Pistia stratiotes Water Lettuce • 2 Treatment Ponds East and
West • 2 Control Ponds East and
West • 2 year experiment 2005-2007
– Measured for pH – electrical conductivity – Turbidity – Suspended Solids – Nutrients: N + P
Synthesis Reported a marked improvement in water quality All ponds did have seasonal change in measured levels due to increased runoff.
Percent reduction is highlighted, listed from East to West as compared to control ponds.
Electrical conductivity 10.34% and 4.05%*
Total suspended solids 11.21% and 10.44%
Water turbidity 65.5% and 63.3%
pH 6.68% & 9.37%**
* Due to decreased salinity, ** can be attributed to reduced algae and submerged vegetation growth due to surface coverage of WL
Reduced levels of nutrient concentrations
59%
41%
Average P Percent Reduction
Total P (mg l−1)
PO4 3−–P (mg l−1)
61%
39%
East Pond P Percent Reduction
Total P (mg l−1)
PO4 3−–P (mg l−1)
58%
42%
West Pond P Percent Reduction
Total P (mg l−1)
PO4 3−–P (mg l−1)
Synthesis
Reduced levels of nutrient concentrations
7%
42% 51%
East Pond N Percent Reduction
Total N (mg l−1)
NO3 −–N (mg l−1)
NH4 + –N (mg l− 15%
42%
43%
Average N Percent Reduction
Total N (mg l−1)
NO3 −–N (mg l−1)
NH4 + –N (mg l−
22%
42%
36%
West Pond N Percent Reduction
Total N (mg l−1)
NO3 −–N (mg l−1)
NH4 + –N (mg l−
Synthesis
Comparison with Other Approaches Previous studies w/ other similar plants range between 15-40g/kg N and 4-10 g/kg P
This Study Annual removal East Pond: 190 kg/ha N and 24.6 kg/ha P
Annual removal West Pond: 329 kg/ha N and 34.1 kg/ha P
Similar studies have been conducted with water hyacinths showing much higher uptakes and biomass yield 1,980 (kg/ha)/year of N and 322 (kg/ha)/year of P
But those studies were different for multiple reasons 1. That research used a medium with higher concentrations of nutrients 2. These are extrapolated values based on short-term experiments which
can overestimate the uptake rate of the plant
Challenges and Limitations
Transferability Limited by Environmental Conditions • Requires High Concentrations of Nutrients
Growth Rate of WL with Differing N levels
Growth Rate of WL with Differing P Levels
Transferability Limited by Environmental Conditions • Requires High Concentrations of Nutrients • Sensitive to Salinity • Sensitive to Low temperature
Challenges and Limitations
Transferability Limited by Environmental Conditions • Sensitive to Salinity • Sensitive to Low temperature and • Requires High Concentrations of Nutrients
High Cost • Maintenance of optimal plant density required for effective
removal • Use of invasive species requires a closed system
Challenges and Limitations
Potential Applications
• Water Lettuce has great potential for improving water quality in both
agricultural and urban settings
• Harvest Plant Biomass can be reused as a soil amendment or processed into livestock feed
• Emphasizes the need to apply the right plant in the right situation
Discussion Points
Do the benefits of using invasive species outweigh the potential risks?
What could be an effective alternative approach?
image sources: http://www.vt.edu/
image sources: http://www.cd3wd.com
image source: http://members.peak.org/
Treating agricultural -runoff at the source High Performance Native Species
Sources “Our Phosphate Risk” published online, 2008 at http://www.thephosphaterisk.com/issues/health-risks
“Nitrate Risks to your Health” updated online, 2011 at http://nitrate.com/nitrate4c.htm
NOAA National Centers for Coastal Ocean Science Gulf of Mexico Hypoxia Assessment: HYPOXIA IN THE GULF OF MEXICO Progress towards the completion of an Integrated Assessment Revised Publication Aug. 2003 at http://oceanservice.noaa.gov/products/pubs_hypox.htmlNASA
Cogger, C. “Clean Water For Washington: Septic System Waste Treatment in Soil” WSU Dept. of Agriculture published online 1995 at http://cru.cahe.wsu.edu/CEPublications/eb1475/eb1475.html
Grosshans, R. et al, “Cattails for Nutrient Removal and Bioenergy: Current research on Netley-Libau Marsh” International Institute for Sustainable Development and University of Manitoba, 2008.
New Hampshire Environmental Services. “Environmental Fact Sheet: Nitrate and Nitrite: Health Information Summary” Published 2006.
NASA Earth Observatory. “Aquatic Dead Zones” published online July, 2010 at http://earthobservatory.nasa.gov/IOTD/view.php?id=44677.
Guidelines for drinking-water quality, 2nd ed. Vol. 2. Health criteria and other supporting information. World Health Organization, Geneva, 1996.
Lu et al. “Phytoremediation to remove nutrients and improve eutrophic conditions using water lettuce (Pistia stratiotes L.) Indian River Research and Education Center, University of Florida and College of Natural Resource Zhejiang University, China; Springer Press, Published 2010.