Plastic was identified in more than 90 per cent of rainwater samples taken from across Colorado, a new study has found.

Denver, August 14 (WNM) - Plastic shards, beads and fibres were identified in more than 90 per cent of rainwater samples taken from across Colorado, including at more than 3,000 metres high in Rocky Mountain National Park, according to researchers from the US Geological Survey.

The authors write:

Atmospheric wet deposition samples were collected using the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) at eight sites (see map) in the Colorado Front Range. Plastics were identified in more than 90 percent of the samples. The plastic materials were mostly fibers that were only visible with magnification, approximately 20–40 times (X). Fibers were present in a variety of colors; the most frequently observed color was blue followed by red>silver>purple>green> yellow>other colors. Plastic particles such as beads and shards were also observed with magnification. More plastic fibers were observed in samples from urban sites than from remote, mountainous sites. However, frequent observation of plastic fibers in washout samples from the remote site CO98 at Loch Vale in Rocky Mountain National Park (elevation 3,159 meters) suggests that wet deposition of plastic is ubiquitous and not just an urban condition.

General types of particles were classified in the observations (see table). Air mass back-trajectory analysis for site CO98 samples was completed using the HYSPLIT model for 24 hours prior to each sample collection at 500-, 750-, and 1,000-meter altitudes. (National Oceanic and Atmospheric Administration, Urban areas are southeast (approximately 140°) of site CO98, but plastic deposition was more positively identified for westerly storms than easterly storms. In the four blank samples, there was one small translucent fiber observed that might have been plastic. Translucent and white materials, which are the colors of the sampling apparatus, were disregarded in the analyses.

The authors conclude:

The mass of plastic in even the most concentrated samples was not large enough to weigh or reliably estimate. Developing a routine capability to calculate plastic wet-deposition loads is not possible with current (2019) technology. Methods for more accurate estimation of plastic loads are needed. Better quality control to limit cross contamination and methods for estimation of percent recovery of the plastic materials from NADP samples are needed. Retaining NADP filters for subsequent analysis would make a washout deposition network possible with very little added expense. How these plastic materials are accumulating and being assimilated in the environment and biota is unclear. Moreover, the potential effects of these materials on biota is not understood.

It is raining plastic. Better methods for sampling, identification, and quantification of plastic deposition along with assessment of potential ecological effects are needed.

Study here: https://pubs.usgs.gov/of/2019/1048/ofr20191048.pdf