# Microplastic Pollution on the Beaches of the Black Sea in Romania and Bulgaria
## 4 Discussion
Recycling microplastics, however, is more challenging due to their small size, contamination with pollutants, and chemical structure degradation, which complicate both their collection and reuse in industrial processes [60]. The statistical analysis of data regarding the microplastic pollution of beaches located in Romania and Bulgaria aimed to determine whether the zoning of these beaches generated statistically significant variability. Furthermore, the analysis sought to identify the geographical regions in which beaches were more exposed to microfiber pollution, as well as to determine which specific beach was the most affected by this type of contamination. The one-way ANOVA included the number of microplastics as a variable and the distributions for the zones of each beach as observables. Statistical analysis using a one-way ANOVA revealed significant differences between the groups, indicating that at least one group's mean differed significantly from the others, which necessitated further post hoc analysis to pinpoint specific group differences [61]. The characteristics of the mathematical \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Molecular Descriptor** & **PET** & **PA** & **PP** & **PE** & **PU** & **PS** & **PVC** \\ \hline Total A, Å2 & 360.82 & 385.80 & 220.21 & 170.57 & 253.24 & 246.8 & 209.16 \\ Grid A, Å2 & 379.08 & 428.16 & 195.59 & 161.78 & 253.42 & 276.86 & 191.79 \\ V [Å3] & 586.11 & 719.66 & 256.27 & 199.61 & 344.38 & 408.36 & 245.11 \\ Log P & 0.74 & 0.3 & 1.48 & 1.13 & \(-\)0.06 & 1.93 & 1.01 \\ R [Å3] & 52.47 & 62.92 & 15.65 & 9.98 & 20.84 & 39.88 & 14.81 \\ \(\alpha\) [Å3] & 19.22 & 24.89 & 6.09 & 4.25 & 8.35 & 13.91 & 6.18 \\ H\({}_{\text{formation}}\) [kcal/mol] & \(-\)6.96 & \(-\)3.78 & \(-\)0.15 & \(-\)1.68 & \(-\)5.75 & \(-\)2.43 & \(-\)1.27 \\ E\({}_{\text{hidr}}\) [kcal/mol] & 7.36 & 7.64 & 2.318 & 0.42 & \(-\)6.32 & \(-\)0.24 & 0.73 \\ \(\mu_{\text{t}}\), D & 4.59 & 0.004089 & 0.3 & 0 & 3.339 & 0 & 1.58 \\ Mass, amuu & 194.19 & 226.32 & 42.08 & 28.05 & 89.09 & 104.15 & 62.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Calculated molecular descriptors for polymer structures. model used in the ANOVA are presented in Table 4, and it showed relatively good values for the regression coefficients. The Fisher statistic for the ANOVA test indicated that the proposed zoning of the beaches generated very high variability in the contamination of the sand of the beaches with microplastics. The F value of 17.51 suggests that the variability between groups was much greater than the variability within groups. The extremely low \(p\)-value (\(p<0.0001\)) confirms that these differences were statistically significant. The null hypothesis stated that all group means would be equal, while the alternative hypothesis asserted that at least one group mean would be different. Since the \(p\)-value was considerably lower than the 0.05 threshold, the null hypothesis was rejected, meaning that at least one group was significantly different from the others. The R-squared value of 0.89 indicates that approximately 89.67% of the variability in microplastic levels was explained by the differences between groups. This high R\({}^{2}\) value suggests that the location played a strong role in determining the microparticle concentration. The algorithm used for classifying/grouping beach areas based on the contamination of the sand with microfibers was the Tukey test, the results of which are presented in Table 5. \begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline  & **DF** & **Sum of Squares** & **Mean Square** & **F Value** & **Prob \textgreater{} F** & **R-Square** & **0.897** \\ \hline Model & 116 & 80,464 & 693.65 & 17.51 & \textless{}0.0001 & **Coeff Var** & 0.279 \\ \cline{2-8} Error & 234 & 9268.66 & 39.61 & & & **Root MSE** & 6.294 \\ \cline{2-8} Total & 350 & 89,732.66 & & & & **Data Mean** & 22.556 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the ANOVA for the concentration of microplastics in the sand on the beaches.