Across 23 Arctic beaches, plastic appeared in only two sediment samples. But those two samples contained nearly five thousand particles—mostly polypropylene fibres that likely came from a fishing net. Plastic production and plastic waste have increased to such an extent that plastic has become globally ubiquitous.

Recent research has highlighted that plastic has also invaded remote Polar Regions, including the Arctic, where it is expected to accumulate over time. A growing body of research has documented microplastics in the atmosphere, cryosphere, sea surface, water column, sediments, and biota, but contamination levels on Arctic beaches are poorly known.

To fill this knowledge gap, citizen scientists participating in tourist cruises sampled beach sediments during shore visits on Svalbard, Norway. Samples were dried, sieved, visually inspected under a binocular microscope, and putative plastic particles at least one millimetre wide were analysed with ATR-FTIR spectroscopy.

Plastic particles at least one millimetre wide were found in two out of 53 samples from 23 beaches, with mean levels of 196.3 particles per kilogram and 147.4 particles per litre. Those two samples contained six polyester-epoxide particles and 4920 polypropylene fibres.

The fibres likely originated from a fishing net and point to possibly accelerated plastic fragmentation processes on Arctic beaches. Plastic pollution has also increased in the Arctic, with negative impacts on Arctic biota already documented. Although more studies have documented macroplastic and microplastic pollution in different Arctic regions, many blind spots persist.

Because citizen scientists had successfully recorded macrodebris on Svalbard’s beaches and at the sea surface, and had sampled snow on Svalbard, the same setup was used to collect sediment samples for plastic particles at least one millimetre wide. The goal was to obtain microplastic levels from Svalbard’s beaches by engaging cruise tourists in a citizen-science sampling project that could generate baseline data.

The study also aimed to compare microplastic pollution levels with macroplastic pollution recorded during citizen-scientist campaigns conducted at the time of microplastic sampling. The study was conducted with tourist cruise operators during four campaigns to the Svalbard Archipelago: one each in 2016, 2017, 2021, and 2022.

Participants received simple instructions for collecting sediment samples on beaches visited during cruise shore excursions around Svalbard. Most collections took place alongside macroplastic pollution surveys during the 2016, 2017, and 2021 campaigns.

Hand-held GPS devices were used to determine each sampling site’s position. Two different protocols were used to collect sediment samples. For locations one through 21, one aluminium container was filled with sediment from the uppermost two centimetres of an approximately one-thousand-square-centimetre surface area, using a metal spoon, and then sealed with an aluminium lid.

These locations were chosen by convenience: the middle of the beach, without large stones or pieces of wood, and not too wet. Each sediment sample was dried at 50 degrees Celsius in an oven for one to three days. The dry weight was determined, and the volume was measured using a glass beaker.

The sediment was poured into a five-millimetre steel sieve stacked above a one-millimetre steel sieve, and material passing through the sieves was discarded. Obvious non-plastic material, including vegetation, large stones, and shells, was removed.

The remainder was examined thoroughly under an Olympus SZX16 binocular microscope. The lower size boundary was limited in advance to one millimetre, based on the assumption that plastics at least one millimetre wide do not easily become airborne and should rarely contaminate samples.

To test that assumption, a bowl containing Milli-Q water was placed next to the laboratory equipment so the water could catch airborne particles. After five different laboratory days, the water was filtered through five-micrometre pore-size filter paper.

No plastic particles were found on any examined filter, so airborne contamination of sediment samples with plastic particles at least one millimetre wide was concluded not to have occurred. Every suspect particle was checked with ATR-FTIR. Particles classified as non-suspect were clearly sand particles or complete or broken shells, which made up more than 99 percent of the contents.

Any particle that did not clearly belong in the non-suspect category was analysed by ATR-FTIR. In most cases, the initial visual identification was correct and the putative particles were plastic. Some putative particles were instead bicarbonate, cellulose, glass, coal, or metal.

The method therefore gave the researchers confidence that no plastic particle was missed. Because the samples contained uneven amounts, two methods were used to calculate a mean pollution level. The first method treated each of the 53 samples as one unweighted data point, even though the weight and volume of each sample differed.

That calculation produced an unweighted average because every sample was given the same importance. Over six years, citizen scientists collected 53 samples in 23 Svalbard locations. Weight and volume were determined for all 53 samples, but sampled area was measured for only 32 because no area was measured for samples one through 21.

In total, the collection contained 91377.7 grams and 53200 millilitres of sediment. The total surface area sampled for samples 22 through 53 was 1.8432 square metres. Plastic particles at least one millimetre wide were detected in two out of 53 samples, or 3.8 percent.

Table two catalogs fifty-three sediment samples from twenty-three Svalbard locations, recording sample identifiers, sediment weight and volume, polymer type, and micro- and mesoplastic counts normalized per kilogram and per liter. Most visible entries report zero particles, while sample nine from Lomfjord, Rekvekstranda contains polypropylene and four thousand nine hundred twenty particles, corresponding to ten thousand three hundred ninety-nine point five per kilogram and seven thousand eight hundred nine point five per liter.

The table matters because it preserves the sampling metadata and makes the pollution measurements comparable across uneven sample amounts. The 4926 particles recovered from two out of 53 samples were used to calculate mean pollution levels. For pollution levels per kilogram and per litre of sediment, the weighted mean was always lower than the unweighted mean, ranging from 27.4 percent to 62.9 percent of the unweighted mean.

Table three summarizes mean pollution levels across fifty-three sediment samples, separating ME, MP, and their combined category. It reports both unweighted means, which include variability, and weighted means, alongside counts per kilogram, per liter, and per square meter of beach; the latter is based on thirty-two samples.

For ME and MP combined, the unweighted values are one hundred ninety-six point three per kilogram, one hundred forty-seven point four per liter, and three point three per square meter, while the weighted values are fifty-three point nine, ninety-two point six, and three point three.

Figure five shows a dense cluster of greenish microplastic fibres from sample nine at Lomfjord, Rekvekstranda, in Svalbard. The authors identified these fibres as polypropylene using ATR-FTIR analysis, and their unusual abundance meant they examined ten percent subsamples rather than the entire sample.

This matters because the fibres’ shapes allowed some longer and shorter particles to pass through the one-millimetre sieve, requiring a modified counting procedure. Figure six shows six pink microplastic particles from sample thirty-one at Gåshamna, Svalbard, all identified as polyester-epoxide.

Their maximum lengths range from one point nine to three point eight millimeters, with the scale bars representing zero point five millimeters. This visual makes the reported finding tangible: a single sample contained six distinct particles, corresponding to two point zero eight particles per kilogram, three point fifty-three per litre, and one hundred four point seventeen per square metre.

Although only two out of 53 Svalbard beach samples contained plastic particles at least one millimetre wide, the result supports the observation that meso- and microplastics have invaded the remotest places on Earth. One possible reason for the measured pollution levels is the lower size limit of one millimetre.

Previous studies found that microplastics no larger than 25 micrometres accounted for 80 percent of particles in Arctic deep-sea sediment, 82 percent in the water column, and 88 percent in sea ice samples. Because particles smaller than one millimetre were excluded, smaller plastic particles present at the 23 sampling locations were likely missed, and contamination levels were likely underestimated.

The sampling design also influenced the estimates because only one sample per beach was taken from 2017 to 2021 as part of the pilot study. Sampling larger areas or retrieving more samples is a more adequate approach when pollution levels are low or patchy.

One beach where plastic particles were recorded had the highest sampling intensity: 20 samples containing 54.4 kilograms in total. That increased the likelihood of finding plastic particles compared with a site where only one sample was taken. Figure one maps the Svalbard beach locations where microplastic sediment surveys were conducted during four campaigns in 2016, 2017, 2021, and 2022.

Yellow dots mark locations where plastic was found, while red dots mark locations where none was found; bracketed numbers identify the corresponding entries in Table one. This geographic overview matters because it shows how the authors distributed citizen-science sampling across the archipelago, including the more structured sampling at locations twenty-two and twenty-three.

The study remains important because relatively little is known about pollution levels in the Arctic, even though the Arctic appears to be an accumulation zone for plastic pollution with pollution levels increasing rapidly. Future citizen-science campaigns are recommended to monitor macroplastic and sample for microplastic pollution using systematic sampling approaches, as was done for samples 22 through 53 in this study.

Citizen scientists are willing and able to quickly learn and conduct various sampling protocols, including relatively difficult ones, when instructions are well-written and well-rehearsed. The study therefore foresees many productive collaborations between scientists and citizen scientists in the future.

The study found sparse but highly concentrated plastic particles at least one millimetre wide on Svalbard beaches. Because smaller particles and patchy pollution were probably missed, systematic citizen-science sampling is essential for tracking future accumulation.