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Tier 2
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Original research — experimental, observational, or case-control study. Direct primary evidence.
Environmental Sources
Marine & Wildlife
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Impact of aged and virgin microplastics on sedimentary nitrogen cycling and microbial ecosystems in estuaries
The Science of The Total Environment2023
47 citations
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Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Score: 60
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0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.
Researchers compared how weathered versus new microplastics affect nitrogen cycling in estuary sediments and found that aged microplastics had a faster, more significant impact on key processes like denitrification. Weathered polystyrene particles also increased nitrous oxide emissions, a potent greenhouse gas. The study suggests that the environmental risks of microplastics grow as they age and weather in natural settings.
Microplastics (MPs) entering the environment undergo complex weathering (aging) processes, however, the impacts of aged MPs on estuarine nitrogen cycling and microbial ecosystems remain largely unknown. In this study, a 50 days microcosm experiment was conducted to investigate the response of sedimentary nitrogen (N) transformation processes, NO emission and microbial communities to virgin and aged MPs (PE and PS) exposure. We found that aged MPs influenced sediment nitrogen turnover more rapidly and profoundly than virgin MPs and showed type and dose-response effect. During the first 10 days, higher concentration (3 % by weight of sediment) aged MPs (both PS and PE) treatments significantly promoted denitrification (ANOVA, P < 0.05), while virgin MPs treatments had weak effect on denitrification, compared with the control (P > 0.05). Moreover, higher concentration aged PS-MPs remarkably enhanced NO emission on the 10th day, while NO was consumed in the control. After 50 days incubation, there was an overall increase in nirK gene abundance exposed to MPs, and nosZ gene copies in aged PS treatments were around twice that in the control based on qPCR (P < 0.05). The function prediction also showed significant elevation of relative abundance of denitrification and DNRA relevant genes in bacterial community. In addition, aged PS treatment (3 %) recruited specific bacterial and archaeal assemblies, with Sedimenticolaceae, Lentimicrobiaceae, SCGC_AAA011-D5, SG8-5, Lokiarchaeia, and Odinarchaeia selectively enriched in the treatment. Our study highlighted that virgin and aged MPs had different impact on sediment nitrogen cycling, and the ecological risks of aged MPs should be concerned since all MPs eventually get weathered when they enter the environment.