Scientists suspected that more than 70% of microplastics from water samples from the world’s oceans could get there during the collection of samples. An article about this was published in the Marine Pollution Bulletin.
Researchers at the University of Staffordshire (UK) investigated the problem of procedural contamination when taking water samples for analysis of contained microparticles. Scientists show that a significant amount of microplastics and microfibers of clothing and equipment of scientists are mixed with plastic already in the environment, which interferes with an objective analysis of its amount in nature.
“In the field, this can be due to the dynamic nature of the environment — wind or other weather conditions, the steps required to obtain samples, and the close range scientists need to obtain and store samples,” says Claire Gwinnett, one of the authors research. “In a mobile laboratory, this is often due to the use of small, multi-purpose rooms.”
The data was collected while traveling on the Hudson River. A team of scientists monitored pollution sources by collecting samples from all possible sources: crew clothing, bags, ship parts. They cataloged these sources, and considered pollution “natural” and not procedural, unless the microplastics looked like one of the items in the catalog.
Research has shown that unless strict protocols are used when sampling water, such as metal buckets for surface samples and Nansen bottles for submerged samples, then 71% of the microparticles in the sample get there as a result of procedural contamination. The same was true for the study of samples: without special protection, 68% of microplastic particles in the samples ended up there as a result of contamination.
In the article, the authors also provide advice borrowed from forensic practice to help reduce the proportion of contaminated samples.