Effects of Hydrogen Peroxide on Cyanobacterium Microcystis aeruginosa in the Presence of Nanoplastics

Abstract

Hydrogen peroxide (H2O2) is a common control measure for cyanobacterial harmful algal blooms (cyanoHABs), but local contaminants may alter its effects. Here, we aim to understand the control of cyanoHABs by H2O2 in light of nanoplastic contamination using a multistressor framework. We utilized a high-throughput full-factorial experiment to capture the multistressor impacts of H2O2, nanoplastics, temperature, and light on a toxigenic strain of the freshwater cyanobacterium Microcystis aeruginosa. In addition to revealing independent inhibitory effects of H2O2 and nanoplastics on cell abundance and microcystin production, our high-throughput system also identified non-additive, interactive effects. Specifically, we found that nanoplastics weakened the inhibitory effects of H2O2 on cell abundance and microcystin production. In addition, we discovered that nanoplastics restricted the degradation of H2O2, partially explaining this non-additive effect. Because combined H2O2 and nanoplastic still curbed growth, we expect H2O2 will remain an effective control measure even with background nanoplastic pollution. Our findings illustrate the importance of taking local stressors, including anthropogenic contaminants such as nanoplastics, into account before H2O2 is applied to control cyanoHABs.

Toxicity of nanoplastics to zooplankton is influenced by temperature, salinity, and natural particulate matter

“…49,55 The selected range for this study therefore reflects suspected concentrations of microplastics in locations with a high amount of plastic pollution, and also follows ranges considered in other acute tests and studies on nanoplastic fate. 26,27,51,56 With the ongoing degradation of plastics into nanoplastics and the growth in the disposal of plastic litter, 13 NP concentrations in the environment could increase even further, with possible hotspots near shorelines where concentration of microplastics 57 and degradation may be more significant. 9,58 In addition to the nanoplastics used in this study, we also combined naturally occurring particulate matter, including natural colloids and organic matter.…”

“…However, environmental context can enhance or mitigate nanoplastic toxicity. 26,27 Nanoplastic toxicity and rates of nanoplastic ingestion by organisms depend on both environmental and particle features. 16,[28][29][30] Natural colloidal matter and organic matter interact with NPs, generating heteroaggregates, inducing faster sedimentation, 31 and limiting their bioavailability.…”

Nanoplastic State and Fate in Aquatic Environments: Multiscale Modeling

“…Nanoplastics are known to pose toxicity risks to aquatic ecosystems and organisms. 3,4,8,12,21 Nanosized plastic debris has been reported to interact and cross biological barriers, including epithelial tissue and cell membranes. 12,22 Owing to their natural hydrophobicity and high surface area-to-volume ratio, nanoplastics can adsorb organic chemicals, such as polycyclic aromatic hydrocarbons (PAHs) 23−25 and persistent organic pollutants (POPs) 26 and can enhance transportation of these chemicals through various environmental compartments, such as soil, water, and sediments.…”

“…3,4,8,12,21 Nanosized plastic debris has been reported to interact and cross biological barriers, including epithelial tissue and cell membranes. 12,22 Owing to their natural hydrophobicity and high surface area-to-volume ratio, nanoplastics can adsorb organic chemicals, such as polycyclic aromatic hydrocarbons (PAHs) 23−25 and persistent organic pollutants (POPs) 26 and can enhance transportation of these chemicals through various environmental compartments, such as soil, water, and sediments. 27−29 Ultimately, the toxic effects triggered by nanoplastics or adsorbed chemicals are largely contingent on ingestion or other forms of uptake by organisms, 6,12,21,25,27,30−32 including humans.…”

Cyanotoxins within and Outside of Microcystis aeruginosa Cause Adverse Effects in Rainbow Trout (Oncorhynchus mykiss)

“…Harmful algal blooms dominated by Microcystis are a global concern as their frequency and severity continue to impact the ecological and socioeconomic value of freshwater ecosystems. − These blooms typically produce cyanotoxins including microcystins, a family of over 250 congeners that can cause lethality and health impairment in humans and wildlife. − …”