Comment on “Spatial distribution of microplastic concentration around landfill sites and its potential risk on groundwater”

doi:10.1016/j.chemosphere.2021.131376

Chemosphere

Volume 284, December 2021, 131376

https://doi.org/10.1016/j.chemosphere.2021.131376 Get rights and content

Abstract

This paper discusses some critical weak points and mistakes identified in the original paper. The authors disregarded the importance of field blanks, sampling equipment, and well specifications for proper quality assurance and control. Beneficial field practices guarantee highly reliable results of laboratory analysis for microplastics. In addition, polymer type (chemical composition) and shape (form) are different classification criteria, but the authors mixed these in their description. The distribution and transport of microplastics should be properly understood, along with a knowledge of groundwater flow conditions, such as flow direction and velocity, in the study area.

Section snippets

Improved field practices

There is currently no widely accepted global standard protocol for groundwater sampling of microplastic (MP) analysis for example, in terms of the sampling device or pre-treatment method and sample amount (Koelmans et al., 2019; Re, 2019; Wong et al., 2020). However, there are some logical and reasonable procedures, based on past knowledge and experience in this field, that must be followed because the quality of the field work involved in sampling groundwater substantially affects the

Systematic classification of polymer type and shape

In the paper, the authors stated that the polymer types occurred in the following order: nylon (70%), pellets (18%), foam (6%), fragments (3%), fibers/PVC (2%), and polythene (1%) (Fig. 2 in their paper). However, they confused the polymer type with polymer shape, thereby making an error. MPs when classified by their type (chemical composition) involve polypropylene (PP), polyethylene (PE), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and polyamide (PA) (

Combined interpretation of MP distribution and hydrogeology

Fig. 4 in the paper shows the spatial distribution of the concentration of MPs at both sampling sites. However, the authors did not present a suggested contour for the groundwater levels (equipotential lines). Thus, the detailed flow direction of the groundwater is unclear, making it difficult to understand the distribution and transport of contaminants. Although the migration of MPs might be different from the advection and dispersion of typical species dissolved in groundwater, the

Other comments

Here, we would like to comment on some other errors in the paper. We attempted to determine what the “PP” in Figs. 3 and 4 represented. We first assumed that it might be polypropylene (PP), considering the abstract and Table 1. However, in the figures, “PP” should represent “plastic particle”. Therefore, the authors should refrain from using the same abbreviations for different terms to avoid confusion. In addition, the authors used the same symbol for different sampling locations in Fig. 1,

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This work was supported by Korea Environmental Industry & Technology Institute (KEITI) through Measurement and Risk assessment Program for Management of Microplastics Program, funded by Korea Ministry of Environment (MOE) (2020003110010). We appreciate helpful comments by the reviewers.

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There are more references available in the full text version of this article.

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Citation Excerpt :
Large diameter hand dug wells are also one of sources for plastic pollution of groundwater due to airborne MPs and inappropriate dumping of plastics into them (e.g., Selvam et al., 2021). Even the groundwater wells themselves may be a source of MPs contamination of groundwater as the well casings, screens and connection pipes are often made up of various plastic materials (Lee et al., 2021). Aging of these materials can gradually emanate substantial amounts of MPs into groundwater.
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Citation Excerpt :
Many other soil MP studies have forgot to report the equipment used to collect soil samples for MP analyses (Huang et al., 2020; Liu et al., 2022; Xu et al., 2022). According to Lee et al. (2021), it is important to describe the type of equipment used to collect samples for MP research because this equipment can be a potential source of MP contamination. Samandra et al. (2022) reported the use of a polyamide rope, which could be a potential source of groundwater contamination in this study.
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Comment on “Spatial distribution of microplastic concentration around landfill sites and its potential risk on groundwater”

Abstract

Section snippets

Improved field practices

Systematic classification of polymer type and shape

Combined interpretation of MP distribution and hydrogeology

Other comments

Declaration of competing interest

Acknowledgement

J. Hazard Mater.

Water Res.

Trends Anal. Chem.

Sci. Total Environ.

Sci. Total Environ.

Sink to river – river to tap

A Review of Potential Risks from Nanoparticles and Microplastics