Trade-off between runoff and sediments from treated erosion plots and polyacrylamide and acrylamide residues

Objective: The present study aimed to evaluate the quantitative effect of polyacrylamide (PAM) on runoff and soil loss, and the amount of PAM polymer and acrylamide (AMD) monomer emissions from experimental plots under laboratory conditions. Materials and methods: The different levels of treatment of 0, 0.4, 0.6,1, 2, 3, 4, and 6 g m(-2) PAM were applied to small plots of 0.05 m(2) installed in the Rainfall and Soil Erosion Simulation Laboratory of Tarbiat Modares University, Iran, with a simulated rainfall intensity of 72 mm h(-1), duration of 0.5 h, and slope of 20% (i.e., 11.5 degrees) applied to a silty loam, similar to that for real conditions. To determine the optimal level of PAM application for soil and water conservation under laboratory condition, PAM polymer and AMD monomer were measured in outing runoff and sediment. An analytical technique based on a spectrophotometer was developed to quantify the amount of PAM polymer present; the determination of amide groups by the NBM was also formulated for the quantification of PAM polymer. The background AMD concentrations in runoff and sediment were determined using the EPA method 8032A in triplicate. The analysis of AMD was performed on a gas chromatograph system equipped with an electron capture detector and Clarity 42 Data Acquisition software. Results: The results proved a significant PAM polymer emission in runoff and sediment (P < 0.001), a significant AMD monomer emission in output runoff (P < 0.02), and no significant AMD residue in the output sediment (P > 032). The optimal amounts of PAM application that are based on PAM and AMD residues in runoff and sediment and minimum soil loss were at rates of 2 and 0.4, and 2 and 1 g m(-2), respectively. Conclusions: The results of this research could be helpful in providing appropriate information to address environmental concerns regarding PAM application for soil erosion control as well as in conservational and engineering planning. (C) 2016 Elsevier B.V. All rights reserved.