Enhanced waste treatment by wetlands with duckweed

PRIMARY PROGRAM ELEMENT:  Fisheries and Aquatic Resources
SECONDARY PROGRAM ELEMENT:  Contaminants; Ecosystems

DURATION:   Start Date: 9/1/1998   End Date: 8/31/1999

INVESTIGATOR: Clifford B. Fedler

Parker, Nick C. (Texas Cooperative Fish and Wildlife Research Unit)


Texas Cooperative Fish and Wildlife Research Unit
Lubbock, TX
Phone: 806-742-2851
Fax: 806-742-2946
The pressure on the environment and our natural resources is increasing rapidly, especially with the growth of the population. Even though we may have the economical capacity to deal with environmental problems via high-tech approaches, these technologies will not provide an immediate solution for communities with a population less than about 50,000, the segment of society that has the highest need for low-cost solutions. Wetlands have been used for centuries to treat wastewater, either intentionally from community sewage, or unintentionally from non-point source runoff. As long as the organic loading rate was minimal, effective treatment of the organic matter to non-polluting end products was achieved. When the organic loading was too high for the wetland, serious pollution resulted. Since these wetlands were known to effectively treat wastewater, many design engineers and researchers focused their attention on designing man- made (constructed) units to try and mimic the natural systems. Our greatest challenge is to develop reliable and appropriate wastewater treatment technologies that are within the economical and technological capabilities of all these small communities that cumulatively produce a great burden on our environment. If we are to utilize wetlands to treat wastewater more effectively and at a reasonable cost, we may find there are advantages of closely simulating the natural environment. Our overall objective is to determine the quality of protein that can be produced in a mixed culture of duckweed species for the purpose of producing the most economical sellable by-product while determining the level of wastewater treatment provided to the waste produced by the livestock industry.

APPLICATION OF RESEARCH: Data from this research will be used to provide new design procedures and guidelines to the Texas Natural Resource Conservation Commission and other regulatory agencies for the design and operation of wetlands or other natural systems for effective treatment of wastewater.

PROGRESS: 2/3/2000
The use of constructed wetlands for treatment of wastewater and stormwater runoff is a highly accepted approach for both municipal and agricultural purposes. These wetlands have proven to be inexpensive and relatively low in maintenance, while achieving astonishing levels of treatment. However, there is always room for improvement. Natural wetlands have been processing and cleaning the Earth's water supply since the beginning of time with a great level of success. Scientists and engineers are now turning to them for design tips and guidance. The focus of this study is to observe the effects of wetting and drying cycles, commonly seen in natural systems, on aquatic plant growth and effluent water quality (specifically with respect to nitrogen, phosphorus, pH, and suspended solids.) Theoretically, strategic alternation of wet and dry conditions could greatly enhance the performance of the nitrogen cycle, reaching higher rates of conversion of unwanted forms of nitrogen to nitrogen gas. This rate increase would be due to the creation of aerobic and anaerobic conditions necessary for nitrification and denitrification to occur, respectively. However, the optimum cycle for nitrogen processing must be balanced with that which is conducive to the health and productivity of the aquatic plants, which are the backbone of the system. Typha spp. (cattails), Paspalum distictum (knotgrass), and Eichhornia crassipes (water hyacinth) were selected for this study based on survivability in the West Texas region and characteristics rendering them desirable for use in treatment wetlands. This project primarily addresses the affects of variable wet and dry cycles on plant growth and begins to explore the effects on nutrient removal. Two experiments related to the project were completed in December 1998 and July 1999, and two additional experiments, currently underway, will be completed in August of 2000. In the first two experiments, twenty-one 10 ft x 1 ft x 1 ft fiberglass tanks (cells) were arranged to receive cattle feedlot run-off mixed with municipal water to maintain a total nitrogen concentration of approximately 30 ppm. Twelve 2.5 gallon nursery pots were placed in each cell and four specimens of each of the previously discussed species were planted at random in the pots. Influent valves and standpipes on the effluent end of the cell controlled wet, followed by dry conditions within the cells. During dry conditions, approximately two inches of wastewater was maintained in the bottom of the cells, available to the extremities of the plant roots. Cycles ranged from one week wet and one week dry to four weeks wet and two weeks dry. Control cells were continuously wet. At the end of each dry period, one specimen of each species was harvested and weighed for total biomass production and a representative sample analyzed for total Kjeldahl nitrogen (TKN). All three species survived and grew very well in the control tanks. Water hyacinth, commonly thought of as floating plant, established healthy root systems in the soil matrix during wet periods. However, during dry periods, the relatively shallow root system was not able to extract sufficient water from the soil matrix. Water hyacinth did not grow well when subjected to any dry cycle.

Reimbursable Funds; aquatic; contaminants; ecosystem science; plants; wetlands

ACC NO: 5002860
PROJ NO: 402

Ecological risk assessment of herbicides and other non-point source pollutants
in freshwater aquatic ecosystems


DURATION:   Start Date: 10/1/1992   End Date: 10/1/2001

INVESTIGATOR: Fairchild, James F.

Mauck, Wilbur L. (Columbia Environmental Research Center)


     Columbia Environmental Research Center
     Columbia, MO
     Phone: 573-875-5399
     Fax: 573-876-1896

WHY: Non-point source pollution is the most pervasive water quality threat to aquatic resources in
the United States. Non-point source pollution is degrading numerous wetlands, streams, lakes, and
estuaries which are important habitats for trust aquatic resources such as endangered species and
anadromous fishes. Both direct (toxic) and indirect (alteration of habitat) impacts of non-point source
pollution can occur. However, non-point source pollutants cannot be regulated using existing water
quality criteria because multiple causes of degradation (pesticides, nutrients, and sediments) occur
over broad temporal and spatial scales and are difficult to identify and control using existing
regulatory laws. Thus, information is needed to support identification, assessment, remediation, and
prevention of non-point source pollution impacts on aquatic resources. WHAT: Cooperative research
between the USDA, EPA, USGS, and the USFWS will be conducted at two Management Systems
Evaluation Areas (MSEAs) located in Iowa (Walnut Creek Watershed, Kelly) and Missouri
(Goodwater Creek Watershed, Centralia) to develop techniques for the identification, remediation,
and prevention of the impacts of non-point source agricultural pollution on aquatic resources. This
work unit will use laboratory acute toxicity tests to determine the potential impacts of various
farming systems on non-target aquatic organisms. Water will be collected following runoff events at
MSEA sites. Samples will be shipped to the ECRC for toxicity testing with four aquatic test species:
fathead minnow (Pimephales promelas), a cladoceran zooplankton (Ceriodaphnia dubia), a vascular
plant (Lemna minor), and algae (Selenastrum capricornutum). Results of analytical and toxicity tests
will be used to identify primary stressors impacting these watersheds. Information gaps related to
primary stressors will be identified. Laboratory and experimental ecosystem studies will be
conducted to determine provide information needed to fill these data gaps. Ecological risk
assessments will be conducted by comparing toxicological responses to measured pesticide
concentrations. Results will be used to rank the relative hazard of pesticides to other potential water
quality factors such as nutrients, sedimentation, temperature, and dissolved oxygen. USDA and the
EPA will use this information to develop alternative farming systems and water quality programs that
will reduce the impacts of non-point source pollution on aquatic resources. Such efforts will benefit
USFWS interests in protecting and restoring trust aquatic resources such as endangered species and
will assist in management goals within the refuge, private lands, and wetland reserve programs of the

APPLICATION OF RESEARCH: The information obtained through this study will help to
determine the potential impacts of non-point source agricultural pollution on aquatic resources of the
midwestern United States and will develop alternative farming systems and water quality programs
to reduce these impacts on aquatic systems.

PROGRESS: 1/27/2000
Progress: An ecological risk assessment of metribuzin was conducted based on the results of single
species, microcosm, and mesocosm studies. A manuscript from this risk assessment is in
preparation. The interagency report of a pond study that examined the aquatic fate of triclopyr was
completed. One manuscript was published in Archives Environmental Toxicology and Chemistry.
Another manuscript concerning the relative sensitivity of 11 aquatic plant species to atrazine,
alachlor, metribuzin, and metolachlor has been accepted for publication in Environmental Toxicology
and Chemistry. Results: Single species, microcosm, and mesocosm studies with metribuzin were
used to conduct an ecological risk assessment of the chemical. Single species laboratory results
previously indicated that metribuzin was highly toxic to a suite of 12 species of algae and
macrophytes, with a median acute toxicity value of 36 ug/L (range 14 to 3000 ug/L). Effective
concentrations in single species and microcosm tests were similar. Structural responses of Najas wet
weight and weight per plant (18 to 24 ug/L 14-d EC50) were more sensitive indicators of metribuzin
toxicity than functional measures of community respiration and gross photosynthesis (47-49 ug/L
14-d EC50) in microcosms. Metribuzin reduced primary productivity of 0.1-ha mesocosms at 38 < X
< 75 ug/L for approximately 14 days but had no effects on macrophyte biomass, fish survival, or fish
growth. Results indicated that either a suite of single-species studies or a site-specific microcosm
test could provide information that was predictive of concentrations causing impacts to outdoor
experimental ecosystems. Metribuzin was highly toxic to aquatic plants but is estimated to be of
relatively low risk to non-target aquatic organisms due to relatively low application rates (< 0.5
kg/ha) and short aqueous dissipation half-life (< 5 d; 0.1-ha mesocosms). Results of the triclopyr fate
study indicated that triclopyr degraded rapidly in mesocosm as predicted by laboratory studies on
photolysis. No effects on non-target monocot plants were observed. A herbicide risk assessment
was conducted for the lower Missouri River. Results indicated that atrazine, alachlor, metolachlor,
and cyanazine posed the highest risk to aquatic plants. However, herbicide risks were low compared
to other threats including hydrologic alteration and non-native invasive species. Results were
published as part of the 1999 USGS Toxic Substances and Hydrology Proceedings.

Base Funds; aquatic; contaminants; plants; populations; toxicology; wetland

ACC NO: 5002346

Cost effective waste treatment through aquatic protein production

PRIMARY PROGRAM ELEMENT:  Fisheries and Aquatic Resources
SECONDARY PROGRAM ELEMENT:  Contaminants; Ecosystems

DURATION:   Start Date: 1/10/1998   End Date: 8/31/2000

INVESTIGATOR: Fedler, Clifford B.

Parker, Nick C. (Texas Cooperative Fish and Wildlife Research Unit)


     Texas Cooperative Fish and Wildlife Research Unit
     Lubbock, TX
     Phone: 806-742-2851
     Fax: 806-742-2946

The high cost associated with the treatment of wastewater is a major concern to treatment plant
operators, municipalities, industries, agriculture, and even more importantly now, the general public.
Degradation of our natural water resources caused by the discharge of wastewater is also a public
health issue and an environmental concern. Current research dollars have been directed to improve
performance of existing treatment technology. However, our current technology as in conventional
waste treatment plants only partially treats or biodegrades the waste. With adoption of technologies
now being developed, wastewater treatment can provide some level of economic return while
providing an environmentally safe effluent. Under several former grants, a new type of natural
waste treatment system, the Integrated Facultative Pond (IFP), has been developed. An IFP has
been constructed to anaerobically treat animal wastes, and, when integrated with an aquaculture
system, the effluent produced can be used to produce aquacultural products including aquatic plants
and fishes. These aquaculture products can be used directly as feed for animals or further processed
as special rations. In addition, since the aquatic protein is a source of omega-3 fatty acid, fats
deposited in animals and fishes will also contain those fatty acids, thus increasing the nutritional and
economic value of their protein. Due to taste and aesthetics, fish fed a diet containing aquatic plants
(algae) have sold for over 30% more than those fish not fed the aquatic protein. Our primary
objective is to determine the economic benefit of integrating aquatic protein and fish production with
the treatment of wastewater.

APPLICATION OF RESEARCH: The primary tasks of this research are: 1)The production of
fish fed the aquatic plants. 2) The development of an automated aquatic plant harvestor. 3) To
determine and model the changes in wastewater quality due to the aquatic protein production and 4)
To develop an economic analysis program for use by the public.

PROGRESS: 2/2/2000
Problem - Large amounts of nonpoint source pollution have been generated by agricultural activities,
and currently at least 24 states are experiencing serious water quality problems that can be linked to
agriculture (Ancell et al. 1998). The Southern High Plains of Texas and Eastern New Mexico are
responsible for about 25% of the annual cattle production in the United States (Fedler and Parker
1997). The majority of these cattle see the inside of a feedlot. The Southern High Plains contain
approximately 200 feedlots, 87 of which handle 5,000 or more cattle at full capacity (Fedler and
Parker 1997). The average manure production from these feedlots is about 45 million tons annually
and contains 0.31 million tons of total nitrogen (Fedler and Parker 1997). The problem exists in
finding economically feasible ways of reducing the nitrogen levels to be compliant with the standards
set by the Environmental Protection Agency. Wetlands are known to be effective devices in treating
wastewater and, currently, constructed man-made units are being developed to mimic natural
wetland systems. Wetlands differ from aquatic ecosystems in the fact that wetlands dry out or have
no standing water for a period of time. The major function of this research is to try to understand the
wetting and drying cycles of a constructed wetland and to see how these cycles efeect the
nitrification and denitrification processes. Research - The greenhouse that houses the wetland
system contains 23 fiberglass tanks, each being 2ft wide by 2ft deep by 10ft long. The tanks are
connected in pairs except system #6, which contains 3 tanks in the series. The tanks are filled with
sand so that when the tanks contain water, the average water depth throughout the 23-tank system
is 4 in. The aquatic plants that grow in the wetland system include cattails (Typha spp.), knot grass
(paspalum disticum), duckweed (lemna), and some sedges (sedges spp.). The cattails were
manipulated so that each tank contained roughly the same number of plants. Each system, 11 in all,
contains a 30 gallon head tank at the front of the system. The head tank has a continuous flow, fresh
water line attached to it. The fresh water line is regulated to allow only 1 gph flow. The raw waste
line is also attached to the head tank. Thirty-five gallons of raw waste is added to each system every
other day. Each system has a 2-day retention time. The systems are loaded based on BOD
concentration. The BOD of the raw waste was calculated at 235 mg/l. After dilution, the
wastewater entering the system has a BOD of 100 mg/l. The experiment runs on a 9-week cycle. In
week one, every system has wastewater running through it. In week two, one of the systems is
drained and allowed to dry for the rest of the cycle, or 7 weeks. In week 3, another system is
drained and allowed to dry for 6 weeks. In week 4, a third system is drained and allowed to dry for 5
weeks. During weeks 5, 6, and 7 two systems each week are drained and allowed to dry until the
end of the cycle. Week 8 has one system drained and no systems are drained in week 9; then the
cycle begins again. Currently, we are in the middle of the second cycle. The order in which the
systems are drained changes every cycle so that no system remians drained for the same length of
time. At the beginning of every week, water samples are taken at the point were the water exits the
system. Another sample is taken from the system that is not going to be drained during the current
cycle. Each water sample is analyzed for total nitrogen, nitrate, nitrite, total kjekdahl nitrogen, and
ammonia. Current analysis shows that the chemical oxygen demand (COD) of the raw waste is
7590 mg/l, the biological oxygen demand (BOD) of the raw waste is 235 mg/l, and the total nitrogen
of the raw waste is 300 ppm. This is an ongoing experiment with at least two and one half cycles still
to complete. When the cycles are complete and the data is analyzed, the results will provide a better
understanding of the effects that the wetting and drying cycles of wetlands have on the nitrification
and denitrification processes.

Reimbursable Funds; aquaculture; ecosystem science; wetlands

ACC NO: 5001129

Dynamics of wetland seedbanks and vegetation communities in existing and
potential emergent marshes


DURATION:   Start Date: 6/1/1995   End Date: 5/31/1998

INVESTIGATOR: Fredrickson, Leigh, H.

Rabeni, Charles, F. (Missouri Cooperative Fish and Wildlife Research Unit)


     Missouri Cooperative Fish and Wildlife Research Unit
     Columbia, MO
     Phone: 573-882-3524
     Fax: 573-884-5070

This study evaluated the Missouri River floodplain vegetation response in existing and newly formed
wetland and aquatic habitats following the Great flood of 1993. Twelve sites were selected for
intensive study, 4 scoured sites directly connected to the Missouri River, 4 isolated scoured sites, and
4 remnant emergent marshes. Plant species richness and composition of soil seedbanks were
compared to vegetation communities that developed post-flood.

APPLICATION OF RESEARCH: Differences in seedbank and vegetation composition suggest
to wetland managers that newly created sites will not resemble remnant emergent marshes in the
near future, because there is high potential for woody growth to dominate newly created sites.

PROGRESS: 6/15/1999
The number of plant species germinating from soil seedbanks was lower than the number of species
in the standing vegetation (18 and 35 species, respectively). Remnant oxbow lakes averaged 33 plant
species per site and were dominated by emergent perennials and floating leaved species including
river bulrush (Scirpus fluviatilus), water smartweed (Polygonum amphibium var. coccineum), water
primrose (Ludwigia repens), arrowhead (Sagittaria spp.), lotus (Nelumbo lutea), and duckweed
(Lemna minor). Scored sites averaged 37 plant species per site and were dominated by cottonwood
and willow seedlings and a variety of annual forbs, grasses, and sedges such as pigweed
(Amaranthus rudis), eclipta (Eclipta spp.), sprangletop (Leptochloa spp.), millet (Echinochloa spp.),
foxtail (Setaria spp.), red-root sedge (Cyperus erythrorhizos), and Cyperus odoratus.

Reimbursable Funds; birds; ecosystem science

ACC NO: 5001042
PROJ NO: 509

Impacts of global climate change in submerged aquatic vegetation systems
important to wildlife


DURATION:   Start Date: 10/1/1990   End Date: 9/1/1997

INVESTIGATOR: Rizzo, William M.

Stewart, R. (National Wetlands Research Center)


     National Wetlands Research Center
     Lafayette, LA
     Phone: 318-266-8501
     Fax: 318-266-8610

WHY: Seagrasses and submerged aquatic vegetation (SAV) in fresh and brackish waters provide
critical food for waterfowl, provide feeding and nursery areas for many commercial and recreational
fish species, baffle currents, stabilize sediments, and remove nutrients from surrounding waters.
Wildlife habitat based on seagrasses or other submerged aquatic vegetation is expected to respond to
changes in CO2, salinity, and physical disturbance associated with global climate change. Data to
predict the magnitudes of these effects for various species, the potential influences on species
interactions, and the consequences for habitat quality and quantity are lacking. WHAT: Research
objectives are designed to meet needs for information at species, community, and ecosystem levels
of organization. Field and greenhouse experiments are being used to test the effects of global climate
change variables on growth and competitive ability of SAV species. Simulation models will be
developed to predict long-term effects of multiple environmental variables on persistence, structure,
and function of submerged communities. Results will be used to delineate potential shifts in seagrass
and SAV habitat availability along Gulf at Mexico and South Atlantic coasts in response to climatic

APPLICATION OF RESEARCH: Determine the effects of global climate change on production
and community structure in submersed aquatic vegetation.

PROGRESS: 9/30/1997
PROGRESS AND EVALUATION A manuscript on salinity effects on SAV species is in
preparation. A manuscript dealing with our initial studies on the effects of elevated carbon dioxide on
photosynthetic rates is in preparation. A brief summary of these results was published in the
proceedings of the Coastal Society annual meting [Rizzo, W.M., H.A. Neckles, R.G. Boustany, D.R.
Meaux, and M.R. Griffis. Impacts of Elevated Inorganic Carbon Concentrations on the Autotrophic
Components of Coastal Submersed Macrophyte Communities. pp. 761-767, In: T.E. Bigford & R.H.
Boyles, Jr. (eds.). Proceedings of the Fifteenth International Conference of the Coastal Society.
Seeking Balance: Conflict, Resolution and Partnership. The Coastal Society, Alexandria, VA. 74
pp.]. A USGS fact sheet was also prepared to summarize these findings. Papers on our global
climate change research were presented to the Coastal Society and the Society of Wetland
Scientists (3). Sample analyses from our second greenhouse experiment were completed. The
seagrass simulation model was restructured for prediction of suitable areas for estuarine submersed
vegetation. A greenhouse experiment on duckweed growth was initiated, and studies on the effects
of elevated carbon dioxide on phytoplankton growth continue. RESULTS AND CONCLUSIONS
Initial results from the phytoplankton growth experiments indicate that significant increases in growth
resulted from additions of nitrogen, carbon dioxide, and rainwater (via nitrogen). Phosphate additions
had no effect. Photosynthetic rates over 24 h were significantly increased by these treatments, as
was chlorophyll biomass. In addition, ratios of carbon to nitrogen were altered by these treatments,
although ratios in all treatments changed over the experiment.

Global Change; aquatic; coastal; ecosystem science; human impacts; National Wildlife Refuges;
plants; public lands; wetlands

List revised:  October 29, 2000