Comment on the paper “Microplastic contamination of an unconfined groundwater aquifer in Victoria, Australia”

This paper was written to comment on a few important problems of an original paper published in this journal. In the original paper, polyamide (PA) ropes, a kind of plastic, were used for groundwater sampling. Also, polycarbonate, another plastic, was also used as a filter paper although their potential contamination was later evaluated. Although the original authors reported that high levels of PA were not found in any of the 21 groundwater samples, it is still necessary to only use equipment(s) made of non-plastic at every step of the method for an accurate and reliable analysis of the presence of microplastic in groundwater. The original authors collected a total of 3 l for each borehole (1 l for each sample), but for an unbiased and reliable analysis of microplastics, bigger volumes of groundwater samples should be collected. Furthermore, the original authors computed the Pearson correlation coefficients between the analyzed plastic types, but omitted the normality test of the data distribution. If the collected data are not normally distributed, then Spearman rank correlation coefficients are a better option. In addition, we found some important misstatements regarding the results of the analysis.