Combined Effects of Microplastics and Benzo[a]pyrene on the Marine Diatom Chaetoceros muelleri

Abstract

Microplastics are regarded as ubiquitous pollutants in the ocean and have attracted worldwide concerns. Benzo[a]pyrene (B[a]P), one of typical polycyclic aromatic hydrocarbons (PAHs), is commonly detected in marine environment. Once coexisted, the microplastics and B[a]P may interact with each other and result in combined toxicity to organisms, and these remain to be systematically elucidated. Thus, this study aims to investigate (i) the effects of single micro-sized polystyrene (mPS), polyethylene terephthalate (mPET), and B[a]P on cell growth of Chaetoceros muelleri; and (ii) the interaction of microplastics and B[a]P, and their combined effects on C. muelleri. The results showed that both single microplastics and B[a]P at a high concentration of 150 μg/L inhibited the growth of C. muelleri. For single treatment of microplastics, stronger inhibition effects on microalgae was caused by mPET than that of mPS, with the highest IR of 25.23 and 11.17%, respectively. This may be attributed to the obvious surface roughness of mPET. By comparison, the combined effects of microplastics and B[a]P significantly inhibited the growth of C. muelleri as compared with the single treatment of B[a]P (P < 0.05). Synergistic effect was found in the combination of microplastics with B[a]P at high concentrations of 150 μg/L. Interestingly, the antagonistic effect on C. muelleri was observed in the combined treatment of microplastics and B[a]P at low concentrations of 10 μg/L. In addition, the pollutants reduced the content of photosynthetic pigments in microalgal cells. The SOD and MDA content of microalgae increased in the early stage of exposure to pollutants (e.g., Days 1 and 5), but decreased in the later stage (Day 15) compared with the control group. The decreased superoxide dismutase (SOD) and catalase (CAT) activity in single and composite systems may indicate that the antioxidative enzymatic system of microalgae has been inhibited or destroyed. This study will be helpful to further explore the ecological threats of microplastics and PAHs to the marine ecosystem.

Gross Negligence: Impacts of Microplastics and Plastic Leachates on Phytoplankton Community and Ecosystem Dynamics

“…Therefore, PS has a high sorption capacity for aromatic compounds, which shows that the chemical structures of MP monomers influence pollutant composition and pathogenic microorganisms in the plastisphere . Several studies are emerging on the combined toxicities of MP with PAHs, , PCBs and pesticides, , plastic additives, antibiotics, and heavy metals. ,, The sources of some of these pollutants, however, remain unclear as some heavy metals and organic pollutants can also leach from MP. ,,,, As a result, these MP serve as emerging hotspots of pathogenic and hydrocarbon-degrading bacteria vastly different from their planktonic counterparts . Thus, they form niches facilitating accelerated microbial evolution in the plastisphere through horizontal gene transfer of potentially hazardous genes such as antibiotic resistance genes .…”

“…In lakes, PL at environmentally relevant concentrations elicited efficient bacterial growth than natural DOC because the PL were more accessible for bacterial utilization . Thus, further changes in oceanic carbon cycling due to the massive release of MP-DOC and subsequent changes in planktonic community profiles toward pathogenic and pollutant-degrading heterotrophic bacteria are suggested to greatly alter the entire biogeochemical cycling. ,,, Further, MP have been shown to impact minor nutrient cycling, e.g., rupture of the siliceous cell walls of marine diatoms, and diatoms are one of the major groups in oceans as well as in the plastisphere. ,, Another nutrient cycle impacted by MP is cycling of Fe which is an integral part of primary productivity . Desorption processes of pollutants from MP at low pH conditions in the gut of zooplankton reduces the efficiency of lithogenic Fe, which is essential for primary productivity. , …”

“…Therefore, PS has a high sorption capacity for aromatic compounds, which shows that the chemical structures of MP monomers influence pollutant composition and pathogenic microorganisms in the plastisphere. 133 Several studies are emerging on the combined toxicities of MP with PAHs, 80,134 PCBs and pesticides, 81,135 plastic additives, 58 antibiotics, 73 and heavy metals. 79,87,136 The sources of some of these pollutants, however, remain unclear as some heavy metals and organic pollutants can also leach from MP.…”

“…120,128,167,171 Further, MP have been shown to impact minor nutrient cycling, e.g., rupture of the siliceous cell walls of marine diatoms, and diatoms are one of the major groups in oceans as well as in the plastisphere. 63,65,134 Another nutrient cycle impacted by MP is cycling of Fe which is an integral part of primary productivity. 158 Desorption processes of pollutants from MP at low pH conditions in the gut of zooplankton reduces the efficiency of lithogenic Fe, which is essential for primary productivity.…”

Adsorption Behavior of Microplastics as a Carrier of Various Contaminants and Their Ecotoxicity in Aquatic Environment

“…[23][24][25] 또한 산화 스트 레스가 유발되는 등 독성이 증가하였고, 광합성 생물의 경우 엽록소 양과 광합성 활성에도 영향을 미쳤다. [23][24][25][26] 그러나 생 물 및 오염물질의 종류에 따라 생태독성이 완화되는 결과도 일부 보고되었고, 25,26) 동일한 오염물질이라도 고농도에서는 독성이 강화되었지만 저농도에서는 오히려 완화되는 사례도 관찰되었다. 25) 농약의 일종인 클로피리포스(Chlorpyrifos, CPF)가 흡착된 폴리에틸렌을 0.…”