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Mitigating microplastics: What types of plastics are getting into Lake Tahoe and on beaches?

Michelle Gartner
Special to the Tribune

Remember that old polyester base layer you could never get clean, the one stuffed back in your closet because every time you put it on it smelled like you just got back from a five-day backpacking trip?

A welcome change came in the 1980s, performance fabrics made from synthetics that didn’t retain odors and perform better than those stinky ones.

Some of these “newer” materials were made from polypropylene, the world’s second-most widely produced plastic and the most versatile. There’s been a growing trend to recycle synthetic plastics into clothing and polypropylene, or plastic resin number 5, is the “easiest to recycle polymer and one of the most widely used materials for packaging consumer goods,” wrote Edward Kosior, who’s expertise in the plastics recycling sector spans 46 years.

But according to an American Chemistry Council report on polypropylene production and recycling, it’s one of the least recycled post-consumer plastics, at a meager rate of less than 1%.

There are many uses for polypropylene; food containers, drinking straws, boat parts, kayaks and climbing rope just to name a few. It’s also one of the few foreign materials allowed to be used during construction on the shores of Lake Tahoe, but only on a temporary basis.

The issue with polypropylene is that it’s made from petroleum, it degrades into microplastics, and it’s not biodegradable, able to break down and be absorbed naturally into the environment. Like all petroleum-based plastics the world may be stuck with them forever. The National Ocean and Atmospheric Administration reminds, “there is still a lot about plastics in the ocean and Great Lakes that we don’t know, including how long they last or if some materials will ever fully go away.

As for Lake Tahoe specifically, Jenessa Gjeltema, an assistant professor of medicine and epidemiology at UC Davis, shared this about plastics, “Estimates of the (degradation) process ranges from a few years to millions of years, and different environmental conditions impact the timeline significantly. Most of the current knowledge stems from studies conducted for marine or terrestrial environments, which may or may not accurately estimate biodegradation in the environmental conditions at Lake Tahoe.”

WHAT IS KNOWN

What we do know is all plastics are affected by ultraviolet rays and over time, plastics that aren’t manufactured for use as microbeads, given these are already micro, disintegrate to small pieces of plastic called microplastics. And research is pointing to synthetic plastics breaking down into pieces so small that, according to a study by the American Chemical Society, “exposure to nanoplastic might occur via oral inhalation, ingestion, or absorption by the skin in connection with the use of plastic products.”

Polypropylene is more susceptible to UV rays than other popular plastics and can break down faster. The UV light causes the bonds holding the polymer together to break which weakens the plastic. Without the effects of UV or other degenerating influences, it will take this plastic 20 to 30 years before turning into microplastic. UV rays increase the degradation rate more than 10 fold and adding additives can speed it up or slow it down according to another study by the American Chemical Society.

The UV effects are noticeable near of one of the more crowded beaches stretching across the north shore of Lake Tahoe, Kings Beach California State Park. There’s a spot where multiple rows of kayaks and paddle boards sit stacked on a rack and more than 20 line a narrow stretch of sand. To secure the rack and keep the beach from eroding, Tahoe Paddle and Oar arranged piles of sandbags made from woven polypropylene fabric. As the natural rim of Lake Tahoe moves towards its high mark, water breaches these bags and waves lap up and over them.

Three employees working on a busy Thursday afternoon said they were aware of reports that microplastics have been found in Lake Tahoe. In a discussion about potential problems created by the degrading sandbags and microplastics in the lake, their manager, Laura Gray said she was pretty certain, “Placer County approved their permit this year.”

The Tahoe Regional Planning Agency regulates planning in the Tahoe basin through maintaining a code of ordinances that preserve, restore and enhance the Lake Tahoe Region. In Kings Beach, the TRPA relies on Placer County to provide permits and enforce those codes, with the exception of anything to do with the shoreline. Tiffany Good, the TRPA’s shoreline permitting program manager, said complexities of managing shoreline regulations and permitting require a regional approach and are a bit too specific at Lake Tahoe to leave for city, county, state or federal jurisdictions to manage.

Woven polypropylene sandbags are approved for temporary use within the shore zone, but these bags have been there for years and deterioration from the sun’s UV rays is visible. Being on the north shore of Lake Tahoe, as compared to other aspects of the lake, they get the most year-round direct sun exposure.

ACCORDING TO PLAN

The TRPA’s shoreline plan was adopted in October 2018. According to Jeff Cowen, public information officer, “there is no prohibition on (polypropylene) tarps, but a disintegrating tarp in a sensitive area is not allowed and we want to know about it.”

As for sandbags, “The material, (for the permit approval process), is not considered because temporary use should not cause harm, but yes TRPA does not want them used in a degrading state or remaining in place for too long.” Cowen said he didn’t have an allowable use time frame as of press time.

In the initial phase that began this year, the TRPA is focusing on mooring registration in relation to the new shoreline plan and “getting concessions like the paddle company under permit is among next steps. They expect to be meeting with concessionaires about the requirement to come under a permit or update their existing permit next summer,” Cowen stated.

The TRPA is asking concessionaires to become compliant with the new shoreline plan. Water oriented outdoor concessions, both motorized and non-motorized that operate in the shore zone are subject to policies specific to the operation of concessions (Visit http://www.trpa.org/programs/shorezone for information about the new policies.)

Polypropylene sandbags and tarps can be seen all around the lake in various stages of decay. The wind, rain, lapping lake water and UV rays wear down the woven plastic material, breaking the plastic into small pieces of debris.

Back by the paddle boards and kayaks, employees cleaned up what is left of the bags under a pop-up tent, but the massive job to remove the bags holding down the rack is a project for another day.

Across Highway 28, at the paddle shop, Gray said, “It was a lightbulb moment when I realized the sandbags in plastic netting were disintegrating.” According to the TRPA, Tahoe Paddle and Oar sits on private property, but permits are required on the shoreline.

With the help of citizen scientists, there are two science-based organizations are studying plastics in and on the shores of Lake Tahoe, the University of California, Davis Tahoe Environmental Research Center (TERC) in Incline Village, and the Desert Research Institute in Reno. The Institute has the only Fourier Transform Infrared spectroscopy in the U.S. This is a type of infrared microscope specifically used for identifying microplastics, and is fundamental in determining where a specific flake of plastic came from.

Learning who is responsible for a specific article of plastic and how that plastic ended up in the lake can be used to help mitigate the issue with plastics worldwide. There are multiple programs around Lake Tahoe that rely on citizens to gather data and anyone can get involved.

To ensure synthetic plastics are recycled, consumers can send them to companies like Green Guru Gear. They accept truck and bike inner tubes, vinyl banners, tents, backpacks, functional zippers, burlap, climbing rope and wet suits. Visit http://www.greengurugear.com for information.

Michelle Gartner is a freelance writer who lives in Gardnerville, Nevada.


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