Public Lab Research note

Notes from a call on Babylegs (microplastics monitoring)

by stevie | July 08, 2020 20:21 08 Jul 20:21 | #24117 | #24117

On July 2, 13 people joined on a call to share a discussion about microplastics found in water, and the Babylegs monitoring tool.

The call was hosted by Omarú Heras Ornelas and Forest Jahnke from the Crawford County Stewardship Project and attended by members of the organization including Ellen Brooks, Dave Edinger, Vicki Ramsay, Kathleen Tigerman, and Carl Schlech. Crawford County Stewardship Project is interested in starting a microplastics monitoring project in southwest Wisconsin.

The call was also attended by:

  • @maxliboiron the creator of the Babylegs monitoring tool, calling in from Newfoundland.
  • Roxana Castellanos calling in from El Salvador. Roxana got involved in using monitoring equipment last year, and is just getting started and learning about Babylegs.
  • @Grace_Schwartz calling in from Knoxville, Tennessee (soon South Carolina). Grace is interested in using the Babylegs tool as part of a chemistry class in the fall.
  • @eustatic sharing concerns about plastic pollution, specifically nurdles along the Mississippi river bank, calling in from New Orleans.
  • @amocorro calling in from Washington State, and interested in marine debris and education. -@stevie calling in from Miami, interested in hearing more about mircoplastics projects.

Below are some of the notes and takeaways from the call:

An overview of Babylegs by Max Liboiron.

Please note there are also step by step activities and resources on the links below each header.

Design tips:

Please also see this post on building a Babylegs monitor

  • Babylegs is highly adaptable, it has a solid body of some kind, it can be a juice bottle container, kitty litter containers are good.
  • Square bodies are more stable, and water can pass through it more easily. It can be used in a stream/river or in the ocean.
  • You want the mouth to be big enough so that the surface of the water is always be in the mouth. The vast majority of plastics is floating in the first inch and a half of the water. You always want baby legs to have a little air and a little water.
  • It’s designed so the rope and water are close to each other, to run it, for example, from a canoe.
  • Never use cotton baby tights- they sink. Use nylon or silk or blend. More expensive tights will often be easier to pick your sample from.

image description

Image from @maxliboiron's post on Building a babylegs surface trawl

Deployment tips:

Please also see this post on how to use babylegs

  • You can stand in water with it, use it off a boat or use a broom handle or something similar to deploy it from a bridge.
  • If babylegs is not acting the way you want, you can speed up, slow down or change the angle of the rope. You can use something to help you do this, for example, tie Babylegs to a broomstick to get it closer to the water if you’re far away.
  • If you’re deploying from a boat you need to keep it out of the wake of the boat. Boats downwell things on the top. If you’re in a stream, be sure to keep away from things that disrupt the water column, for example sticks in the water. They will affect where the plastics are in the water column.
  • It is suggested that Babylegs is deployed some length of time between 15 minutes to an hour. 30 minutes is generally considered a good amount of time.
  • You should keep your eyes on it while it’s in the water to make sure it doesn’t get large debris stuck in it, or flip over.
  • If you’re sampling near a sewage outflow (or any outflow) wear gloves.
  • Sampling in “gunky” water is discouraged as it will be frustrating. If your water has a lot of biota, you can pick for plastics off them rather than trawling.
  • Plastics you find can be different at different times, rains will affect what you find in the water, time of day, and other factors.
  • If you do multiple samples in the same time/setting, bring multiple tights. Those are your samples. You can't clean the samples of the tights streamside and reuse it. Once you’ve had a chance to process your sample, you can wash the tights and reuse them.
    Once you’ve gathered your sample, store your tights in separate ziplock bags.

Processing your sample tips:

Please also see this post for instructions for processing

  • There are two ways to get your samples off tights, one is to turn them inside out and rinse them into sieve, a fine spaghetti strainer will work- the mesh type, you can work inside the strainer. If tights are grabby we flip them inside out on a tray and analyze them right on the tights.
  • To find the plastic in your sample, you’re looking for things down to 1/2mm in size. You can use your naked eye to do this.
  • Pick anything that might be plastic out with tweezers and put it in a coffee filter. bundle it, stick it in a jar, leave it to dry for 1-2 days. This will tell you a bunch of stuff you picked is organic, because organic material will shrivel.

Identifying your plastics tips:

Please also see this post on how analyze your sample

  • Once your sample has dried, you can use a dissecting microscope (10x or 30x magnification). You don’t want a stronger lense than that. You also want the light to be coming from the bottom to illuminate your sample. (Directions on how to build a microscope here)
  • There’s a guide on Public Lab that can help you figure out if something is plastic, and what it might be. For example how does it feel or react when you touch it.
  • Depending on the type of study you’re doing you can classify the size of your samples as well as type of plastic- film, thread, bead, fragments, nurdles, all come from different things and can hint towards the origin of plastics. Then do a count of your sample. These will also give you hints to your sources, for example, a whole lot of microfibers could indicate a sewage outfall, threads could mean fishing plastics, flecks that are different color, that might be paint chips. The guide on Public Lab will help you break this down.

Other Tips:

  • In this method, you do use plastic to sample plastic, so you need to make sure you don’t have ragged edges, that will fray your rope, or get into your sample. You should smooth the edges of the container you’re using.
  • If you see something that clearly comes from your babylegs tool, don’t count it. To deal with this, we tend to use brightly colored materials to build babylegs - so it’s easy to tell when you have contamination.
  • If you use cheap rope in making your tool, it will shed in the water and get in your sample.
  • Make sure they have a record of what plastics your sample is around. It’s contamination control.

Example technical problems, and how to handle them:

  • One problem people have is that it either dives and drowns or it spins. Both those problems are related to where the holes are and where the strings are. Holes need to be evenly apart, if one string is too short or too long it will dive or pop out of the water. Babylegs can handle multiple holes, these are adjustable.
  • Another problem people have is that they pull it too fast. A lot of people don’t use motorized vehicles so that’s fine. If your water is slow and still, it might not float the way you want. We often ziptie soda pop bottles on the sides, a kitty litter container is one of my favorites. The tights can stretch well around most containers.
  • The smaller the body of Babylegs is, the more finicky it is. Kitty litter is heavy enough that it sits in the water nicely.

image description Image from @maxliboiron's post on Building a Babylegs surface trawl

Use cases of Babylegs:

  • It is designed to be rough and ready to help you see plastics. You can explore questions such as: where some plastics might be more than others, and what are types of plastics there are.
  • Designed to help you see a relative concentration of plastics, not absolute density. It is not designed to be used as a scientific way to measure the density of plastics. What you need for density is knowing how much water has gone through it. There are ways you can estimate this (see below), but the Babylegs alone will not tell you the density of plastics.

Extrapolating to density:

  • All scientific measurements with microplastics and surface water are for surface area, not volume. You don’t get plastics for meters cubed, you get them for meter squared.
  • What you need for density is knowing how much water has gone through it (rate of flow, time it’s deployed, width of Babylegs mouth) divided by amount of plastics.
  • On boats you can use a running or sailing app to see how far you’ve gone, that’s a good enough measure unless you have a big tide or current. There you can calculate an estimate of how much plastics there were in a distance of water. On rivers or streams, you can estimate this with flow measurement techniques.

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Lead image from a Research Note posted by @maxliboiron on How to analyze plastics forensically


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