# An Exploratory Review of Microplastic Pollution, Associated Microbiomes and Pathogens in Water
## 3 Results and Discussion
### Microplastics in Surface Waters
The highest level was found in water from the Xindian River, and the lowest was in Kaohsiung Bay (\(\sim\)36.95 and 0.48 particles/m\({}^{3}\), respectively) [38; 39]. In summary, the average content of MPs in surface waters in Asia oscillated around \(\sim\)12,918 particles/m\({}^{3}\), where most analyses were performed in the period 2018-2019. In turn, the comparison by reservoir type showed that coastal areas had the highest MP level (Table 1, Supplementary File S1--Asia). However, the observed discrepancy between the mean and median values likely reflects site-specific outliers, especially in areas affected by urban discharge or aquaculture. **Europe**: The MPs in surface water level were analyzed on the basis of 50 available publications (Figure 3). The analysis showed that the highest average MP level was found in Denmark (\(\sim\)120,300 particles/m\({}^{3}\)), while the lowest was in Italy and the Mediterranean Sea (Supplementary File S2 Europe). In the case of Italy, the lowest levels were found in Lake Bolsena (\(\sim\)0.34-4.08 particles/m\({}^{3}\)), and the highest were found in the coastal areas of Goro (\(\sim\)50 particles/m\({}^{3}\)) and the Mignone River (\(\sim\)544 particles/m\({}^{3}\)) [40; 41; 42]. The highest MP level in the Mediterranean Sea was 7.68 particles/m\({}^{3}\) in the vicinity of the Aegean-Levantine Sea [43]. Additionally, a study conducted by [PERSON] et al. [44] confirmed the presence of microplastics in the surface waters of the Aegean and Levantine Seas. In this study, 84 samples were collected using a manta net between 2014 and 2020, covering open waters, coastal areas, and enclosed bays (Korfu and Saronikos). Microplastic concentrations varied greatly, ranging from \(\sim\)0.08 to 10.8 particles/m\({}^{3}\), with the highest levels recorded in samples influenced by surface ocean currents. High concentrations of MP were found in surface water in the Netherlands, Portugal and France (\(\sim\)44,961, 51,860 and 17,500 particles/m\({}^{3}\), respectively). In the remaining countries analyzed, the level did not exceed \(\sim\)3400 particles/m\({}^{3}\) (Supplementary File S2 Europe). When analyzing the MP level depending on the type of reservoir, the highest levels of MPs were detected in the coastal areas (\(\sim\)24,372 particles/m\({}^{3}\)), and the lowest were detected in rivers (\(\sim\)8166 particles/m\({}^{3}\)) (Table 2) (Supplementary File S2--Europe). Similar to Asia, the difference between the mean and median values observed in Europe likely reflects the impact of extreme values at specific locations, especially in highly urbanized estuaries or coastal zones influenced by anthropogenic discharge. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type** & \multicolumn{2}{c}{**Amount of MPS (Particles/m\({}^{3}\))**} & **References** \\ \hline \multirow{3}{*}{River} & Median & 32.05 \\ \cline{2-3}  & Average & 12,619.33 \\ \cline{2-3}  & SD & 11,988.37 \\ \hline \multirow{3}{*}{Lakes} & Median & 11,000 \\ \cline{2-3}  & Average & 12,079.07 \\ \cline{2-3}  & SD & 11,475.12 \\ \hline \multirow{3}{*}{Sea/bay} & Median & 322.5 \\ \cline{2-3}  & Average & 14,469.03 \\ \cline{1-1} \cline{2-3}  & SD & 13,745.57 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The average level of MPs in Asia depends on water type (particles/m\({}^{3}\)). **North America**: In the case of the USA (n = 9, Figure 3), the highest level was found in Charleston Harbor Estuary, with MPs at the level of -19,500 particles/m\({}^{3}\). On the other hand, the lowest was found in Chesapeake Bay, in which the detected concentrations ranged from -0.007 to -1.2 particles/m\({}^{3}\)[45; 46]. The analysis of the MPS level in individual types of water reservoirs showed that in the coastal areas, the MP level was the highest; the average was about 4156 particles/m\({}^{3}\), and the lowest in rivers was \(\sim\)3.8 particles/m\({}^{3}\) (Supplementary File S3--North America). The next analyzed country was Canada (n = 9).