Coating paper straws appeared to have little effect on their value of 𝑘 𝑑 . Our finding that PP and PLA can persist in the marine environment for years is consistent with those in the literature; PP and PLA have values of 𝑘 𝑑 that are orders of magnitude lower than those of CDA, PHA, and paper (Figure ). Because CDA, PHA, and paper have been shown to biodegrade in the marine environment and our experimental system was without mechanical action (e.g., waves and abrasives), we consider 𝑘 𝑑 to be the specific surface degradation rate due to biodegradation processes. ).