An increasing number of researches have been published on MPs’ different freshwater
ecosystems worldwide, including lakes, rivers, estuaries, and wetlands in both
waters and sediments. Although the literature on plastics in freshwater is growing,
data are globally disjointed about the evidence of concentrations of MPs and impacts
on environmental freshwater matrices [1]. Besides, the heterogeneity of sampling
protocols, methodologies, techniques, and measurement units among different
researches makes it challenging to compare results and produce a complete picture
of the existing state of understanding [2]. Another critical factor is that MPs<100 μm
(SMPs) are often overlooked; less than 20% of reported studies on freshwater
environments reported MPs below 20 μm. The sampling and analytical procedures
are strictly connected to detecting plastic particles sizes >100 μm. Consequently,
most of the reported studies could have undervalued the concentration of SMPs.
Thus, improvement in detection technologies and pre-treatments methods could
modify the final mean amount of MPs in freshwater environments [3]. Freshwater systems are considered an important source and critical pathway for
MP pollution in coastal and marine environments, especially for the point sources
close to areas with a high density of population and civilization [4–6]. Research in
freshwater environments has detected MPs in Europe, North America, Africa, Asia, and Antarctica. The USA has performed the most research on MPs of all freshwater
microplastics studies, followed by China [7]. Regarding water, the most polluted
areas are Southeast Asia and Europe, while sediments are also highly contaminated
in North Africa and North America [1]. Thus, MPs are widespread pollutants not
only in marine systems but also in freshwater systems. Studies on MPs in freshwater
systems are mainly conducted in rivers, lakes, and estuaries, while new research has
focused on wetlands, stormwater ponds, and reservoirs. However, there is limited
knowledge about MPs in these freshwater environments compared to rivers and
lakes [2, 8]
