Investigating the impact of water-soluble polymers on the metabolic profiles of aquatic organisms and microbes

Whilst existing studies broadly indicate that WSPs possess a lack of acute toxicity, 1-5 it has been recently argued that “the toxicity, transport, fate, and removal efficiency of degraded Polyacrylamide monomer (PAM) needs to be re-examined in light of existing information on both PAM and the acrylamide monomer.”6 While anionic PAM has shown minimal toxicity of anionic PAMs to aquatic life, gill pathology has been observed in rainbow trout exposed to PAM anionic polymer products, suggesting that sublethal concentration effects may cause changes in biological structures and function. It should be noted that some WSPs are classified as mucoadhesive polymers7-9, which provides the potential for them to adhere to biological membranes. Persistent WSPs could also facilitate the concentration of xenobiotics and other agents that would influence their normal metabolism. The principle aim of this project is to investigate changes in metabolic profile when aquatic organisms and microbes are exposed to WSPs and to suggest possible modes of toxicity.

Aims
• To investigate the fundamental biological impact of WSPs on the metabolic profile of aquatic invertebrates and microbes
• To determine the impact of WPSs on growth efficiency in microbes and toxicity thresholds in aquatic organisms
• To develop new analytical tools to elucidate the mode/s of toxicity WSPs have on aquatic life and potentially the impact WSPs may have on ecosystems.

1. Xiong, B., Loss, R. D., Shields, D., Pawlik, T., Hochreiter, R., Zydney, A. L., Kumar, M., 2018. Polyacrylamide degradation and its implications in environmental systems. NPJ. Clean Water, 1 (1), 1−9.
2. Xiong, B., Miller, Z., Roman-White, S., Tasker, T., Farina, B., Piechowicz, B., Burgos, W. D., Joshi, P., Zhu, L., Gorski, C. A., 2018. Chemical degradation of polyacrylamide during hydraulic fracturing. Environ. Sci. Technol. 52 (1), 327−336.
3. Fish Pathology: Third Edition. WB Saunders, Philadelphia, PA.
4. Mallat, J., 1985. Fish gill structural changes induced by toxicants and other irritants: a statistical review. Can. J. Fish Aquat. Sci. 42, 630-648.
5. Bullock, G., Blazer, V., Tsukuda, S., Summerfelt, S., 2000. Toxicity of acidified chitosan for cultured rainbow trout (Oncorhynchus mykiss). Aquacult. 185, 273-280.
6. Kerr, J. L., Lumsden, J. S., Russell, S. K., Jasinska, E. J., & Goss, G. G., 2014. Effects of anionic polyacrylamide products on gill histopathology in juvenile rainbow trout (Oncorhynchus mykiss). Environmental toxicology and chemistry, 33(7), 1552-1562.
7. Brakstad, O. D., Altin, D., Davies, E. M., 2020. Interaction between microalgae, marine snow and anionic polyacrylamide APAM at marine conditions. Science of the total environment, 705, 135950.
8. Salamat-Miller et al., 2005. The use of mucoadhesive polymers in drug delivery. Advanced Drug delivery Reviews, 57, 1666-1691.
9. Arp, H. P. H., & Knutsen, H. 2019. Could we spare a moment of the spotlight for persistent, water-soluble polymers?. Environ. Sci. Technol. 54, (1), 3–5.

Water-soluble polymers (WSPs) are commonly used in industrial, commercial, agricultural and pharmaceutical products and their molecular weights and concentrations vary considerably. Methods commonly used in the analysis of WSPs are often for pure products or formulations with only a few other high MW constituents. These methods, like size exclusion chromatography (SEC) or Gel Permeation Chromatography coupled with Mass Spectrometry (MS) can be frustrated by the impact of the necessary separation steps prior to identification and the limitations of MS when identifying and quantifying polymers. To that end, the employment of a Nuclear Magnetic Resonance (NMR) method to identify, characterize and quantify WSPs in the real-world is reported for the first time. Samples were taken from fourteen UK inland river sites, concentrated via air-drying, freeze-drying or vacuum-drying and analyzed using 1D 1H NMR and 2D 1H Diffusion Ordered Spectroscopy (DOSY) NMR analysis. Seven of the river sites showed the presence of polyethylene glycol (PEG) with a range of molecular weights, evidencing the application of these techniques in analysis of WSPs. Soil percolation models evidenced the proof of principle that these techniques can also be used for the detection of polyacrylamide (PAM) and polyacrylic acid (PAA). This work should better enable the evaluation of the biological impact of WSPs on aquatic organisms in future studies.

Novel use of NMR to characterize and quantify Water Soluble Polymers (WSPs).

Fourteen UK Rivers sampled and concentrated for analysis and screened for WSPs.

Polyethylene glycol was detected in seven of the rivers in ppb concentrations.

Proof of principle to detect WSPs in soil run off evidenced.