DEVELOP AND IMPROVE STRATEGIES FOR MANAGEMENT OF IRRIGATED AGRICULTURAL CROPS AND SOILS
Location: Northwest Irrigation and Soils Research
Title: Toxicity of anionic polyacrylamide formulations when used for erosion control in agriculture
| Weston, Donald - UNIVERSITY OF CALIFORNIA |
| Cahn, Michael - UNIVERSITY OF CALIFORNIA |
| Ogle, R - PACIFIC ECORISK |
| Rothert, Amanda - SOUTHERN ILLINOIS UNIV. |
| Lydy, Michael - SOUTHERN ILLINOIS UNIV. |
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 16, 2008
Publication Date: January 19, 2009
Citation: Weston, D.P., Lentz, R.D., Cahn, M.D., Ogle, R.S., Rothert, A.K., Lydy, M.J. 2009. Toxicity of anionic polyacrylamide formulations when used for erosion control in agriculture. Journal of Environmental Quality. 38:238-247.
Interpretive Summary: Runoff from irrigated agricultural fields contains sediment, nutrients, and pesticide residues that substantially degrade natural surface waters that receive irrigation return flows. While minute additions of polyacrylamide polymer (PAM) to water during field irrigations are known to dramatically reduce contaminant loads in runoff, less is known about how PAM products themselves may affect aquatic life in receiving waters. This study shows that the use of solid or water-based PAM products is preferable to oil-based PAM emulsion products because the former provide the benefits of improved runoff water quality with minimal or no toxic effects to the aquatic organisms living in receiving waters. Oil-based PAM formulations should be used with caution, since non-PAM constituents in this product showed evidence of acute and chronic toxicity to aquatic life at environmentally realistic concentrations. This information provides important guidelines for the safe and efficient use of PAM in irrigated agriculture and suggests how PAM products produced for future agricultural applications may be improved.
Addition of anionic polyacrylamide (PAM) to agricultural irrigation water can dramatically reduce erosion of soils. However, the toxicity of PAM to aquatic life, while often claimed to be low, has not been thoroughly evaluated. Five PAM formulations, including two oil-based products, one water-based product, one granular product and one tablet product, were evaluated for acute and/or chronic toxicity to five species commonly used for freshwater toxicity testing (Hyalella azteca (Saussure), Chironomus dilutus (Shobanov et al.), Ceriodaphnia dubia (Richard), Pimephales promelas (Rafinesque), and Selenastrum capricornutum (Printz)). When applied as an oil-based product, acute toxicity was seen to four of the five species at concentrations less than the 10 mg/L that is often used for erosion control. Toxicity was diminished, but still remained, after passage of the irrigation water across an agricultural field, indicating a potential impact to nearby surface waters. Results from the non-oil-based products indicated minimal toxicity associated with PAM even at concentrations ten times those used in agriculture when applied in the granular form, as a tablet, or in a water-based liquid. These data suggest that other agents in the oil-based products, such as surfactants or emulsifiers, rather than the PAM itself, contribute to the toxicity. Care is required in selecting an appropriate PAM formulation when the potential exists for entry of tailwater to nearby surface waters.