Migration and Transformation Behaviors of Acrylamide

Ⅰ. Migration behavior of acrylamide

According to the structure of acrylamide, taking structure prediction method to estimate that acrylamide is not easy to be adsorbed by soil, which has high mobility in soil. It is easy to leach from soil, pollutes groundwater, and its mobility in sandy loam is higher than that in clay.

Accordingly, as a kind of organic chemical compounds, acrylamide is not easy to be adsorbed on suspended particles or sediments inwater. The Henry constant of acrylamide is very low, and it is less likely to volatilize from water surface and wet soil. In view of its low vapor pressure, acrylamide is also difficult to volatilize from dry soil. Acrylamide will enter the atmosphere in vapor or particle state, but gaseous acrylamide is easy to be adsorbed on particles after entering the atmosphere, and only very little acrylamide will exist in the air as a gaseous form. The granular acrylamide in the air can enter the soil and water environment through sedimentation process or rainwater scouring, and the acrylamide in the soil is easy to infiltrate into the water environment. Therefore, most of the acrylamide entering the environment will eventually enter the water.

Ⅱ. Conversion behavior of acrylamide

Biodegradation is the main way of acrylamide degradation in soil, and one of the main mechanisms is enzymatic hydrolysis. Under aerobic soil conditions, acrylamide chemical can be hydrolyzed by microorganisms to produce ammonium ions, which are oxidized to nitrite ions and nitrate ions by nitrification. In aerobic soil, acrylamide can be degraded by 74% ~ 94% after 14 days; However, acrylamide can be degraded by 64% ~ 89% in soggy anoxic soil after 14 days. It can be seen that aerobic conditions are more conducive to the biodegradation of acrylamide. According to different types and physical chemical properties of soil, the half-life period of acrylamide in soil is estimated to be 21 ~ 36h.

Biodegradation is also the main way to eliminate acrylamide in water. A variety of microorganisms using acrylamide as the only carbon source or nitrogen source can be isolated from water, such as Arthrobacter, Nocardia, Bacillus globulus, Pseudomonas and Rhodococcus. High microbial activity, especially surface microbial activity, can promote acrylamide degradation.

Gaseous acrylamide in the atmosphere can be degraded by reacting with hydroxyl radical (· OH) produced by photochemical reaction, and can also react with ozone. Acrylamide is not sensitive to direct photolysis because it does not absorb sunlight with a wavelength greater than 290nm.

Because acrylamide is highly soluble in water and has a short half-life period, it is less likely to have bioconcentration. Some scholars research on 72h static experiment of troutlet shows that the bioconcentration factor (BCF) of acrylamide in body and viscera were 0.86 and 1.12 respectively, and the overall BCF was 1. Acrylamide had no obvious bioconcentration.