Dynamics of Product Water Chemistry & Defining Native Wetland Species Salt Tolerance and Water Use Rates Holly Sessoms

General Chemistry: CBM product water is sodium bicarbonate rich. When discharged to the surface or applied to the soil, sodium bicarbonate undergoes the following reaction: NaHCO 3 - H + + CO Na ++

Free carbonate (CO 3 ) in solution is now available to bind with calcium in the surface water or soil to form calcium carbonate (CaCO 3 ): Ca ++ + CO 3 -- CaCO 3 Calcium carbonate is relatively insoluble and precipitates from solution, thereby increasing the SAR.

The dissolution of sodium bicarbonate also causes the pH to increase with the formation of sodium hydroxide: Na ++ + H + + CO 3 -- CO 2 + NaOH -

Change in water chemistry for three water qualities over a 9 day time period ( subject to evapoconcentration). Initial vs. Final pH Initial vs. Final EC (dS/m) Initial vs. Final SAR % Change EC % Change SAR % Change pH Powder River 7.4 / / / CBM 7.7 / / / Saline- sodic CBM 7.5 / / / Average % Change:

Change in product water chemistry - from discharge to irrigation nozzle: SourcepHSAREC mmhos/cm Outfall Pump Irrigation Nozzle Average % Change (outfall to nozzle) 16%23-60%24-31% Aaron Dejoia, Cascade Earth Science

Changes in product water chemistry - from discharge to downstream location: Mean values pH -- EC dS/m SAR practical SAR true Sue Draw DC Site Site 4 (below res.) % Change: (discharge to Site 4) 28.3% increase <1% decrease 31.1% increase 59.4% increase Source: Patz, Marji J. Coalbed Methane Product Water Chemistry on Burger Draw, Wyoming, M.S., Department of Renewable Resources. University of Wyoming. May, 2002.

Suggested range in EC and SAR of irrigation water for various soil textures: Soil TextureEC range (mmhos/cm) SAR upper limit FloodSprinklerFloodSprinkler Very Coarse sand, loamy sand Coarse sandy loam Medium loam, silt loam Medium fine clay loam, sandy clay loam Fine Silty clay loam, sandy clay, clay, silty clay Source: Western Fertilizer Handbook

Discharge standards as of April 25 th, 2003 : Irrigation Season –Powder River Max EC 2.5 dS/m Max SAR 6.0 –Tongue River Max EC 1.5 dS/m Max SAR 4.5 Non-Irrigation Season –Powder River Max EC 2.5 dS/m Max SAR 9.75 –Tongue River Max EC 2.5 dS/m Max SAR 7.5

Reduce product water volumes through the use of halophytic wetland species, thereby obtaining an economically viable volume of water for treatment methods while enhancing wetland function.

Objectives: Identify appropriate wetland species Define the maximum salt tolerance of each species Determine water use rates relative to open water evaporation Determine how wetland design may optimize plant health – water table height Determine the extent of salt accumulation in plant tissue, ion selectivity? Determine if stratification does occur and to what extent

Halophyte Background: Halophytes are plants found growing under naturally saline conditions (Aronson, 1989) and are sodium tolerant. Patz et al., 2002 found that CBM product water, released into a channel, will alter plant species composition by favoring salt tolerant wetland and riparian plants.

Halophyte Background: Of these wetland species, American bulrush, Maritime bulrush, Baltic rush, Cattail, Inland saltgrass, Prairie chordgrass, and Nutall’s alkaligrass appeared to be thriving (Patz et. al., 2002).

Summary of reported salt tolerance and water use: SpeciesReported salinity tolerance ET Rate Scirpus americanus (American bulrush) 42.5 dS/m (Duncan, 1974) 6.6 mm/day to 13.8 mm/day (Towler, 1999) Scirpus maritimus (Maritime bulrush) 77 dS/m (Duncan, 1974) Juncus balticus (Baltic rush) Tolerates ‘brackish’ water (Duncan, 1974) Typha latifolia (Cattail) 22.5 dS/m (Hootsmans and Wiegman, 1997) ‘some salinity’ (Duncan, 1974) mm/day (Allen et al., 1992) 4-12 mm/day (Snyder and Boyd, 1987) 3-10 mm/day (Pauliukonis and Schneider, 1999). 6.6 mm/day to 13.8 mm/day (Towler, 1999) Distichlis spicata (Inland saltgrass) 70 dS/m (Aronson, 1989) Spartina pectinata (Prairie chordgrass) Tolerates ‘brackish’ water (Duncan, 1974) Puccinellia nuttalliana (Nutall’s alkaligrass) 11.0 dS/m (Ungar, 1974) ‘has salt tolerance’ (Aronson, 1989)

Hypotheses : Native halophyte water use rates will exceed evaporation rates and species will tolerate elevated salinity levels over that of “average” CBM product water. Constructed wetlands can be utilized to reduce product water volumes, thereby increasing the feasibility of other water management options while providing a beneficial use.

Design: 7 native wetland species Columns constructed of 10” PVC pipe, 40 inches deep Gravel substrate Randomized block design 4 Replications, 16 columns per replication 2 “blanks” per replication 2 open surface evaporation pans

Study Protocol: Planted starter plants Jan. 27, 2003 All columns filled with tapwater When plants no longer appeared dormant, began watering with CBM water (Feb. 18 th )

Study Protocol Study Protocol: Progressively sodic water chemistry: Initial: SAR=11.6, EC=3.10, pH=8.3 Mid: SAR=23.0, EC=3.50, pH=8.1 Final: SAR=36.0, EC=3.53, pH=8.0 Water plants once per week Allowed for “drawdown” in 18” water table columns Continuous accumulation of salts through evapoconcentration

Study Protocol Treatments:  Seven Plant Species  Two water tables: at the surface, 18” below the surface  Depth of sampling

Monitor: Water use rates once per week Plant health - thickening of leaves, leaf burn, lack of water uptake, death Biomass production - harvest plants every 8 weeks (or when plants start to seed) Plant salt uptake and preferential selectivity of ions Collect water samples once per month at three depths within the columns - stratification ?

Expected Results : Salinity and water table tolerance will allow for some prediction of riparian community succession in channels receiving product water. Salinity tolerance and water use rates will provide some baseline data. Allow for prediction of the feasibility of constructed wetlands for treatment of product water.

So what have we learned so far?

18” water table doesn’t work: Plants appear to die from lack of water 27 of 28 treatment columns are dead

Average weekly water use rates of all treatments and average pan evaporation from first harvest to second harvest.

Water use (mL) per gram of biomass produced.

Average pH values per treatment over a 3 month sampling period.

Average EC values (dS/m) per treatment over a 3 month sampling period.

Average SAR values per treatment over a 3 month sampling period.

Gee whiz: Constructed wetland = ½ a football field can consume 11,520 gallons of water per day.

Jim Bauder Bauder crew BLM DOE