|Lentz, Rodrick - Rick|
Submitted to: Journal of Chromatography
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1999
Publication Date: N/A
Citation: N/A Interpretive Summary: Runoff from furrow irrigated fields contains sediment, phosphorus, and other nutrients that enter surface waters as non-point source pollutants. A new practice applies small amounts of anionic polyacrylamide (PAM), a long-chained polymer, to some of the irrigation water used to water furrow irrigated crops. PAM reduces sediment losses in irrigation runoff by 80 to 99%, and removes 80 to 95% of other pollutants ordinarily present in runoff water. While PAM itself has low toxicity, PAM products used in agriculture may contain up to 0.05% of a toxic material called acrylamide monomer. Acrylamide degrades rapidly in soil and water, but it is soluble and may potentially be taken up by plants irrigated with treated water. This study developed a method for measuring the concentration of acrylamide that had been added to harvested corn, bean, sugar beet, and potato tissue. This procedure will be used to determine if acrylamide can accumulate in crop tissue and threaten the irrigated crop quality.
Technical Abstract: Polyacrylamide (PAM) is a widely used product for a large number of applications. Many of the emerging applications are in the area of agriculture. PAM is blended with pesticides as a thickening agent, is added to irrigation water to minimize soil erosion, and is used as a medium for hydroponically grown crops. While Pam is stable and considered to be safe, it contained 0.05% residual acrylamide (AMD) monomer, a neurotoxin and carcinogen. In this work, residual AMD was analyzed in a variety of crops that were grown under PAM treatment to stabilize soil erosion. Corn, potato, sugar beets, and beans were analyzed for AMD. A sample of the crop was homogenized with water, the water layer was filtered and derivatized with bromine to from the 2,3-dibromopropionamide. The derivative was then extracted with ethyl accetate and converted to the more stable 2-propenamide prior to gas chromatographic analysis using the electron capture detector. Capillary Carbowax columns were used. All crops tested showed 10 ppb of AMD. Furthermore, it seems that AMD is not stable when it comes in contact with the crop tissues. In the presence of plant tissues, AMD will disappear as a function of time. Beans blended with 100 ppb AMD for 10 minutes yielded a recovery of only 22%. For a bean sample that was soaked with 500 ppb AMD solution for 18 hours, the recovery was 7%. Other crops showed different AMD recoveries.