Low-density polyethylene microplastics as a source and carriers of agrochemicals to soil and earthworms

Abstract

Environmental contextMicroplastics, long recognised as contaminants in aquatic ecosystems, are increasingly of environmental concern for terrestrial ecosystems. This study focuses on the potential of microplastics to act as carriers of agrochemicals and the subsequent effects on soil biota. The results indicate the need for further studies into how soil properties influence both the degradation of microplastics and their role as pollutant carriers. AbstractMicroplastics (MPs) are of environmental concern to marine ecosystems owing to the evidence of their presence in and adverse effects on organisms, but studies to address this problem on soils and its biota are scarce. Several questions can arise related to this major environmental problem and its impact on terrestrial ecosystems, mainly, whether MPs can transport contaminants (e.g. pesticides) to the soil matrix and if they can be a carrier of pesticides to soil biota. To contribute to the understanding of these issues, earthworms (Eisenia fetida) were exposed for 14 days to soil containing two different sized MPs (5mm and 0.25 µm–1mm) that were either previously sprayed or not with chlorpyrifos (CPF). Acetylcholinesterase (AChE) activity and thiobarbituric acid reactive substances (TBARS) were measured to track the exposure of the earthworms to MPs, both non-sprayed and sprayed with CPF. The behaviour of the earthworms in the test containers and the movement of MPs in the soil were assessed. The concentration of CPF in soil at the end of the experiment differed between the treatments with MPs of different sizes (17.9ngg−1 and 2442ngg−1 for large and small MPs, respectively). Despite the ability of the MPs to release CPF to the soil, the earthworms avoided the contaminated MPs at the highest contaminant level. At a lower concentration of CPF (large MPs), the earthworms avoided the MPs, but the contact time with contaminated soil was higher, as shown by the enhanced level of TBARs and AChE inhibition. However, no evidence of MPs uptake was recorded, thus it was not demonstrated that MPs can be carriers of pesticides to earthworms.

Soil Science Challenges in a New Era: A Transdisciplinary Overview of Relevant Topics

“…[80][81][82] It has also been pointed out that plastics could act as carriers of inorganic and organic contaminants in the water-soil interface, releasing these contaminants into the environment and affecting soil (micro-)organisms, with adverse consequences for the food web. 83,84 As a result of increased environmental awareness, biodegradable, oxo-biodegradable, and compostable plastics have been proposed as environmentally friendly alternatives to conventional plastics. 85,86 However, the ecotoxicological implications of these materials are not well studied or they have sometimes been reported to have unanticipated problems such as low environmental degradation under realistic conditions.…”

“…80-82 It has also been pointed out that plastics could act as carriers of inorganic and organic contaminants in the water-soil interface, releasing these contaminants into the environment and affecting soil (micro-)organisms, with adverse consequences for the food web. 83,84…”

Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments

“…Environmental pollution by microplastics (MPs) and nanoplastics (NPs) has raised growing concerns in the last two decades, also as a result of the increasing evidences regarding the direct and indirect negative effects of such contaminants on both marine [1] and soil biota [2,3], and the potential of bioaccumulation and transfer to humans through the food chain. A vast and recent literature accounts for the role of microplastics (those within 0.1-5 mm size being typically considered) as accumulators and carriers of several persistent organic pollutants (POPs) and heavy metals, which can then affect aquatic organisms [4] as well as soils contaminated by MPs, e.g., through sludges from civil wastewater treatment plants [5,6].…”

Microplastic contamination caused by different rearing modes of Asian swamp eel ( Monopterus albus )

“…Their ingestion of plastic particles not only may cause mechanical damage, inflammation and microbiota dysbiosis of intestinal tracts (Burgos‐Aceves, Cohen, Smith, & Faggio, 2018; Guzzetti, Sureda, Tejada, & Faggio, 2018; Jin et al., 2018; Lei, Liu, et al, 2018; Qiao et al., 2019; Savoca et al., 2019), but it could also induce oxidative and immune stress, metabolic disorders and detoxification suppression in other vital tissues, such as livers, gills and haemolymph (Lei, Wu, et al, 2018; Yu et al., 2018). Moreover, microplastics can act as carriers of other pollutants such as heavy metal and persistent organic pollutants (POPs), thereby strengthening their biotoxicity (Rodríguez‐Seijo, Santos, da Silva, Cachada, & Pereira, 2019). Additionally, some studies have indicated that the reproductive process of aquatic animals may be impaired by their exposure to microplastics (Pitt et al., 2018; Sussarellu et al., 2016).…”