Organic Pollutants Associated with Plastic Debris in Marine Environment: A Systematic Review of Analytical Methods, Occurrence, and Characteristics

Abstract

Plastic pollution has become one of the most serious environmental problems, and microplastics (MPs, particles < 5 mm size) may behave as a vehicle of organic pollutants, causing detrimental effects to the environment. Studies on MP-sorbed organic pollutants lack methodological standardization, resulting in a low comparability and replicability. In this work, we reviewed 40 field studies of MP-sorbed organic contaminants using PRISMA guidelines for acquiring information on sampling and analytical protocols. The papers were also scored for their reliability on the basis of 7 criteria, from 0 (minimum) to 21 (maximum). Our results showed a great heterogeneity of the methods used for the sample collection, MPs extraction, and instruments for chemicals' identification. Measures for cross-contamination control during MPs analysis were strictly applied only in 13% of the studies, indicating a need for quality control in MPs-related research. The most frequently detected MP-sorbed chemicals were polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs). Most of the studies showed a good reliability (>75% of the total score), with 32 papers scoring 16 or higher. On the basis of the collected information, a standardizable protocol for the detection of MPs and MP-sorbed chemicals has been suggested for improving the reliability of MPs monitoring studies.

Keywords: beach; microplastics; organic pollutants; seawater.

Figure 1

PRISMA flowchart of the study selection process.

Figure 2

Time trend of publications.

Figure 3

Geographical distribution of the reviewed papers (the number near the country name refers to the number of papers).

Figure 4

Distribution of MPs color in the reviewed studies (some papers reported more than one color).

Figure 5

Polymer type reported in the reviewed papers (EVA = ethyl vinyl acetate; PA = polyamide; PE = polyethylene; PET = polyethylene terephthalate; PP = polypropylene; PS = polystyrene; PUR = polyurethane; PVC = polyvinylchloride. Others refer to a very low percentage of polymer types reported in only one article or mentioned in studies only as “others”).

Figure 6

Percentage of score for each criterion. The percentage of the global papers score is calculated summing the single scores obtained from all the reviewed studies.