Combinatory effects of microplastics and emerging contaminants on alga Chlamydomonas reinhardtii

In oceans today, there is much concern about the effects of microplastics (MPs) and other emerging contaminants (ECs). Here, the authors investigated the combinatory effects of the MPs poly(vinyl chloride) (PVC) and acrylates/C10–30 alkyl acrylates cross-polymer (AC) (which are commonly found in face wash), together with 2-phenoxyethanol (an EC commonly used in soaps). The model photosynthetic unicellular alga Chlamydomonas reinhardtii was used to study the potential of these pollutants to initiate algal blooms. It was shown that AC alone resulted in a greater decline in algal biomass as compared with PVC in the short term (14 days). While algal cultures exposed to PVC registered the highest increase in concentrations of the chlorophyll a pigment, it was the combinatory effects of each MP and 2-phenoxyethanol that were the most pronounced in terms of the large increase in algal biomass and the formation of extracellular polymeric substances. Proliferative growths of C. reinhardtii after prolonged exposure to AC–EC contaminants show potential for initiating algal blooms in aquatic environments. Hence, AC should be considered for regulation of waste water removal into water bodies, and other combinations of MPs and ECs should also be investigated.