Inhibitory effect of microplastics on soil extracellular enzymatic activities by changing soil properties and direct adsorption: An investigation at the aggregate-fraction level

Yu, Huiming; Ping, Fan; Hou, Junhua; Dang, Qiuling; Cui, Dongyu; Xi, Beidou; Tan, Wenbing

doi:10.1016/j.envpol.2020.115544

Cited by 148 publications

(53 citation statements)

References 45 publications

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“…Our results showed that soil pH increased with PE polymers, which agrees with previous research on that topic (Qi et al, 2020;Wang et al, 2020). However, recent research indicates that soil type may also play a role (Boots et al, 2019;Yu et al, 2020); for example, depending on the soil organic matter content acid buffering and retention of major cations may change (Jiang et al, 2018). In addition to the soil type, the presence of plant species in the system may also influence microplastics effects on soil pH (Lozano et al, 2021b), as plants could potentially mitigate the effects of microplastics on soil pH in comparison to a bare soil.…”

Section: Microplastics Increased Soil Phsupporting

confidence: 92%

“…Microplastics could alter soil microbial communities (Fei et al, 2020;Wiedner et al, 2020;Yi et al, 2020), affecting enzymatic activities (Hargreaves and Hofmockel, 2014). Indeed, recent research has showed that microplastics could affect nutrient and/or substrate availability (Yu et al, 2020;Zhou et al, 2020;Lozano et al, 2021b), likely due to microplastic absorption or its competition for physicochemical niches with microorganisms (Yu et al, 2020). Microplastic shape and polymer type may also play a role.…”

Section: Introductionmentioning

confidence: 99%

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Microplastics Increase Soil pH and Decrease Microbial Activities as a Function of Microplastic Shape, Polymer Type, and Exposure Time

Zhao

Lozano

Rillig

2021

Front. Environ. Sci.

198

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Microplastic pollution is a topic of increasing concern, especially since this issue was first addressed in soils. Results have so far been variable in terms of effects, suggesting that there is substantial context-dependency in microplastic effects in soil. To better define conditions that may affect microplastic-related impacts, we here examined effects as a function of microplastic shape and polymer type, and we tested if effects on soil properties and soil microbial activities change with incubation time. In our laboratory study, we evaluated twelve different secondary microplastics representing four microplastic shapes: fibers, films, foams and fragments; and eight polymer types: polyamide (PA), polycarbonate (PC), polyethylene (PE), polyester (PES), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polyurethane (PU). We mixed the microplastics with a sandy soil (0.4% w/w) and incubated at 25°C for 31 days. Then, we collected soil samples on the 3rd, 11th, and 31st day, and measured soil pH, respiration and four enzyme activities (soil enzymatic activities). Our results showed that microplastics could affect soil pH, respiration and enzymatic activities depending on microplastic shape and polymer type, effects that were altered with incubation time. Soil pH increased with foams and fragments and overall decreased in the first days of incubation and then increased. Soil respiration increased with PE foams and was affected by the incubation time, declining over time. Overall, acid phosphatase activity was not affected by shape or polymer type. β-D-glucosidase activity decreased with foams, cellobiosidase activity decreased with fibers, films and foams while N-acetyl-β-glucosaminidase activities decreased with fibers and fragments. Enzymatic activities fluctuated during the incubation time, except N-acetyl-β-glucosaminidase, which showed a declining trend with incubation time. Enzymatic activities were negatively correlated with soil pH and this relationship was less strong when microplastics were added to the soil. Our study adds to the evidence that research should embrace the complexity and diversity of microplastics, highlighting the role of microplastic shape and polymer type in influencing effects; additionally, we show that incubation time is also a parameter to consider, as effects are dynamic even in the short term.

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Section: Microplastics Increased Soil Phsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Microplastics Increase Soil pH and Decrease Microbial Activities as a Function of Microplastic Shape, Polymer Type, and Exposure Time

Zhao

Lozano

Rillig

2021

Front. Environ. Sci.

198

View full text Add to dashboard Cite

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“…Microplastic additions to soil have varying effects on the overall microbial community composition and activity, likely as a function of concentration and chemical composition of MP (Liu et al, 2017;Machado et al, 2018Machado et al, , 2019Yu et al, 2020). The underlying mechanisms can be assumed to be in the change of soil properties, especially bulk density, which improves the aeration of the soil and could thus stimulate aerobic microorganisms; or more generally speaking MP induces a shift in the microbial community composition (Liu et al, 2017).…”

Section: Hypothesized Indirect Effects Of Microplastic On Plant Host Extraradical Soil Environment and Microbial Communitiesmentioning

confidence: 99%

“…On the other hand, there are studies showing negative effects of MP on enzyme activities, e.g., polyethylene mulching film reduced catalase, laccase, and phenol oxidase (Yu et al, 2020). Differences among studies can be explained by use of different MP types, concentrations, and experiment durations.…”

Section: Hypothesized Indirect Effects Of Microplastic On Plant Host Extraradical Soil Environment and Microbial Communitiesmentioning

confidence: 99%

“…Differences among studies can be explained by use of different MP types, concentrations, and experiment durations. Some MP types might have toxic effects (additives, absorbed pollutants, see section "Hypothesized direct effects of microplastic on AMF") or alter the soil properties in a way which is disadvantageous for some species, thus reducing overall activity and enzyme production (Yu et al, 2020). These MP-induced reduced microbial activities could also have an indirect effect on AMF: it could prevent synergistic interactions between AMF and other microbes or reduce positive interactions between AMF and "mycorrhiza helper bacteria" if their activity is decreased as a consequence to MP pollution.…”

Section: Hypothesized Indirect Effects Of Microplastic On Plant Host Extraradical Soil Environment and Microbial Communitiesmentioning

confidence: 99%

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Potential Effects of Microplastic on Arbuscular Mycorrhizal Fungi

2021

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Microplastics (MPs) are ubiquitously found in terrestrial ecosystems and are increasingly recognized as a factor of global change (GCF). Current research shows that MP can alter plant growth, soil inherent properties, and the composition and activity of microbial communities. However, knowledge about how microplastic affects arbuscular mycorrhizal fungi (AMF) is scarce. For plants it has been shown that microplastic can both increase and decrease the aboveground biomass and reduce the root diameter, which could indirectly cause a change in AMF abundance and activity. One of the main direct effects of microplastic is the reduction of the soil bulk density, which translates to an altered soil pore structure and water transport. Moreover, especially fibers can have considerable impacts on soil structure, namely the size distribution and stability of soil aggregates. Therefore, microplastic alters a number of soil parameters that determine habitat space and conditions for AMF. We expect that this will influence functions mediated by AMF, such as soil aggregation, water and nutrient transport. We discuss how the impacts of microplastic on AMF could alter how plants deal with other GCFs in the context of sustainable food production. The co-occurrence of several GCFs, e.g., elevated temperature, drought, pesticides, and microplastic could modify the impact of microplastic on AMF. Furthermore, the ubiquitous presence of microplastic also relates to earth system processes, e.g., net primary production (NPP), carbon and nitrogen cycling, which involve AMF as key soil organisms. For future research, we outline which experiments should be prioritized.

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