Biomonitors Use Living Organisms to Test Water Quality

The University of Arizona Water Resources Research Center administers the Section 104B program of the Water Resources Research Act. Funded by the U.S. Geological Survey, 104B funds support small research projects investigating water issues of state and regional importance; only faculty at Arizona state universities are eligible for 104B funding.

Following are research results of recent 104B projects:

Estimation Of Acute Upper Lethal Water Temperature Tolerances Of Native Arizona Fishes, Corissa J. Carveth, Ann Widmer, Scott A. Bonar, and William Matter, University of Arizona. Stream temperatures have been rising in Arizona since the early 1900s. Although native fishes in Arizona have previously been considered tolerant to high temperature, little is known about the effects of temperature on native fishes in the Southwest. The study estimated the upper thermal tolerance of 11 native and 7 nonnative fish species found throughout Arizona. Fish were acclimated for a 2-week period at 25ºC and 30ºC. A rate of change of 0.3ºC min-1 was then used to expose fish to increasing temperatures. Among the species acclimated to 25ºC, desert pupfish mosquito fish and Gila topminnow were most tolerant to high temperature. Speckled dace, spikedace and loach minnow were least tolerant. Surprisingly, several native Arizona desert fishes are not as tolerant to high temperatures as common nonnative fish species from other areas. These native species may be sensitive to increasing water temperatures in Arizona’s streams and rivers. They may also be susceptible to being outcompeted by nonnative fishes that are more heat-tolerant.

Measurement of Estrogenic Activity in Sludges and Biosolids, David M. Quanrud, Robert G. Arnold, Wendell P. Ela, Jonathon Chorover, University of Arizona. A number of organic compounds responsible for estrogenic activity in municipal wastewater readily survives conventional wastewater treatment and are either discharged to surface waters or accumulate in sewage sludge. Nonylphenol (an important estrogen mimic) and several other compounds thought to be responsible for estrogenic activity in wastewater effluent are moderately hydrophobic; they tend to separate from water and accumulate onto solid particles.

In this project, the fate of estrogenic activity and nonylphenol during secondary wastewater treatment and sludge digestion at wastewater treatment facilities in Tucson and Los Angeles was examined. Methods that were developed to extract estrogenic compounds from sludges and biosolids were used to determine how much estrogenic activity and nonylphenol survive sludge processing at wastewater treatment plants. Based on one-time sampling efforts conducted at three wastewater treatment plants, anaerobic sludge digestion was found to be not effective in degrading nonylphenol in sludge. Composting (an aerobic process) of finished biosolids reduced nonylphenol content by about 75 percent. Thus, project results indicate that aerobic processing steps (e.g. composting) should be further studied as a technique to reduce estrogenic compounds such as nonylphenol in biosolids prior to disposal.

Impact Of Drought On Management Of Salt Sensitive Plants With Reclaimed Water, Ursula K. Schuch, University of Arizona. The objective of the study was to determine the performance of salt sensitive plants when irrigated with reclaimed or potable water and to determine how those plants performed under drought stress. Plants used in the experiment included the desert willow, yellow bells, Chihuahuan sage, and moss verbena. When plants were irrigated with saline water, desert willow and yellow bells had no visual symptoms of injury; desert willow had less leaf biomass and yellow bells had less root biomass when irrigated with reclaimed water. Sage and verbena canopy sizes were smaller when irrigated with reclaimed compared to potable water. Sage also showed some signs of leaf burn during the months of July and August.

Plants were then water stressed by withholding water and their physiological response was measured. In general, plants watered previously with reclaimed water had less leaf area and took longer to wilt than plants with more leaf area that had been watered with potable water. After plants were re-hydrated, those grown with reclaimed water sustained less damage than those grown with potable water. However, accumulation of salts were measured in the root zone of plants irrigated with reclaimed water and over time may lead to problems. Salt sensitive plants can be produced with reclaimed water but depending on the species, may grow to a smaller size compared to plants irrigated with potable water. In a short-term drought experiment plants irrigated with reclaimed water sustained less damage compared to those grown with potable water. Long-term accumulation of salts in the root zone is a concern and needs to be monitored.

MS student Bridgette Howard samples her two permeable reactive barrier columns for treating acid mine drainage containing 25 mg/l copper.

Clean-up of Acid Mine Drainage by Microbes, Jim A Field, Reyes Sierra-Alvarez, University of Arizona. The uncontrolled release of acid mine drainage from abandoned mines and tailing piles in Arizona threatens the state’s water resources. Acid mine drainage introduces elevated concentrations of sulfate, ferrous iron and other dissolved metals as well as radionuclides to groundwater and receiving surface water.

The project studied the potential of permeable reactive biobarriers (PRBs) for the remediation of acid mine drainage. PRBs provide an innovative, low-cost solution to prevent contaminant migration in groundwater. The technology is extremely simple involving trenches intercepting contaminated plumes. The trenches are filled with porous materials, nutrients and substrates to encourage the development of an active microbial population capable of metal removal. Results indicate that there is a great potential for anaerobic biobarrier systems to remediate high influent pH, sulfate and metal concentrations in acid mine drainage with high efficiencies. A significant finding is the discovery that zero-valent iron is an effective substrate for the microbes involved in the clean-up of acid mine drainage.

Controlling Salt Accumulation to Enhance Sustainability of Subsurface Drip Irrigation, Thomas L. Thompson, Art W. Warrick, University of Arizona. Salts introduced into soils in irrigation water are difficult to effectively leach with subsurface drip irrigation (SDI), a highly efficient means of delivering irrigation water and fertilizers to crops. Growers then have to rent expensive sprinkler systems to leach out salts. An effective means to predict the need for leaching with sprinklers would be of economic benefit to growers and would improve the sustainability of SDI systems. Project goal was to measure salt distribution in SD-irrigated crops with and without the use of sprinklers, and compare actual results with salt distribution predicted by a mathematical model. Salt concentrations near the soil surface (<10 cm) were more than twice those near the SDI tubing. Model results over-predicted salt concentrations when using saline irrigation water. Therefore, model predictions need to be improved to provide a tool for effective salt management.