Airborne Trash at Saguaro National Park

 

What goes up must come down!

Releasing balloons into the sky has long been a tradition for many people. We release balloons to celebrate our loved ones and commemorate milestone events such as weddings and birthdays. However, what goes up inevitably comes down. Balloons that fly into the sky eventually drift down into oceans, forests, farms, and deserts. When they land in Saguaro National Park, they become a type of trash that, along with plastic bags that also get lifted into the sky, can be hazardous for wildlife.

 

A cluster of balloons found in the park

NPS Photo

How many balloons are in the park?

A sudy to determine how many desert tortoises live in Saguaro National Park inadvertently provided the best information for how many balloons and bags there may be in protected areas like Saguaro. Erin Zylstra, a PhD student at University of Arizona, used a technique called distance sampling to survey for tortoises along randomly placed transects. While looking for tortoises, Erin and her crew also recorded rattlesnakes, plastic bags, and balloons they encountered on the transects.

Based on these surveys, Erin was surprised to find that there were more balloons per acre than either tortoises or rattlesnakes. She estimated that there were nearly 63 balloons per square kilometer in the Rincon Mountains, which can be extrapolated to approximately 16,987 balloons in the entire park district of 271 square kilometers (about 105 square miles).

Zylstra and her assistants surveyed 120 transects, each one kilometer (about 2/3 mile). They found plastic bags on 35% of them, balloons on 55%, and either balloons or bags on 68%. They counted a total of 56 plastic bags (mostly grocery bags) and at least 94 balloons that were predominantly made of latex (Zylstra, 2012).

The number of balloons and plastic bags varied around the park, but not in relation to roads. The Rincon Mountains had significantly more clusters of trash, which Zylstra believes was due to the prevailing winds, which blow trash from west to east in the Tucson area. Density of balloons in the Tucson Mountain District was 39.2 per square kilometer, or approximately 3,966 in the entire district. You can read the full study here.

Zylstra, E. 2013. Accumulation of wind-dispersed trash in desert environments. Journal of Arid Environments 89:13-15.

 

Why are balloons and plastic bags bad for the park?

Balloons and plastic bags take away from the experience of visitors at Saguaro National Park. They degrade the aesthetic of the environment, but they also can harm wildlife such as desert tortoises, which may ingest pieces of trash or become entangled in the ribbons and strings that are commonly attached to balloons.

Plastic from balloons and bags can also affect the health and functions of soil and water when they break down into microplastics, where they can be ingested and incorporated into the tissues of animals.

"Generally speaking, when plastic particles break down, they gain new physical and chemical properties, increasing the risk that they will have a toxic effect on organisms. The more likely it is that toxic effects occur, the larger the number of potentially affected species and ecological functions." - Science Daily (An underestimated threat: Land-based pollution with microplastics | ScienceDaily)

Balloons are generally made of rubber, latex, polychloroprene, or a nylon fabric. Latex comes from the sap of the tree Hevea brasiliensis and is biodegradable, but it can take months or years for latex balloons to degrade, depending on the environmental conditions. Balloons made from metalized nylon such as foil balloons are not biodegradable and may persist in the environment for years.

 

What can you do to help?

If you must use balloons, do not use helium balloons, and make sure to properly dispose of them. You can avoid plastic bags by using reusable bags when you shop. If you see a balloon, plastic bag or other trash in the park, safely remove them and toss them into appropriate garbage bins.

Thanks for your help in keeping our park clean and safe for visitors and wildlife alike!