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.