Tips and FAQ’s
Can I use glass mason jars? Isn’t the inside of the lid coated with BPA or BPS plastic?
Mason jars are a great candidate for sample jars, since they have a wide mouth for scooping surface water. “Regular” mason jar lids with a BPA or BPS (plastic) coating can be used in a pinch - it creates a very small possibility for error, but unless the jar lids are old, or the water sample in the jar is stored in a warm room for a long time or in direct sunlight, it is unlikely that the plastic coating will degrade into the water. This can also be a great entry to a discussion about the role of plastic in our everyday experiences.
You can also purchase mason jar lids that have a silicon coating (silicon is a plastic-rubber hybrid, and much more durable than an ordinary plastic) instead of a BPA coating, like these (just check the sizes against your jars to be sure they'll fit). I’ve had students who have gotten creative and used foil over the lid of the jar secured with a rubber band and carried them back to our classroom space more carefully than they would a sealed jar. Or, you can do the filtration in the field right away, no lid needed, and just transport the filters back in the trays, as long as they’re covered. Since this is a citizen science procedure, we're working with the understanding that perfection is unlikely, but the goal is to control for as much error and variability as we can.
What is Nile Red? Is the stain safe?
The dye, Nile Red, is a powder and is very low risk itself. To become a usable stain the powdered dye can be prepared in several different solvents (acetone, hexane, methanol, etc.), which are all common laboratory materials. In the small quantities required for this testing (1-3 mL per test), these solvents are quite safe with proper clothing and ventilation. We always suggest using eye protection, gloves, and a well-ventilated area as precautions to be sure there is no risk of contact or exposure to any of the vapors, since these solvents evaporate quickly. Our first priority is safety for participants, especially for students! The whole procedure can also be done outside if desired.
Nile Red is not typically sold pre-mixed by lab materials vendors but hobbyist forensics companies sell it dissolved in both methanol and acetone + hexane. They developed both solutions specifically for microplastics studies and package them in glass bottles. If you'd like to prepare your own stain that is also fine!
Can I stain more than one filter at once?
Yes! As long as the filter papers are not touching, if two or more filter papers fit in the same glass dish you can stain them at once. You can choose whatever size glass dish or bowl works for your needs, as long as you rinse it well between uses.
Would testing the same water body multiple times provide useful data?
Long term data is absolutely useful! The more, the better - the goal is to populate a database that will be a resource for students or researchers who are investigating local questions (such as the relationship between rainfall, seasonality, food webs, etc.). This can also help show seasonal trends and long term patterns.
Will the Nile Red stain organic material? Can I add a hydrogen peroxide digestion step to the process?
Yes, an optional additional hydrogen peroxide step can be useful for treating organic material. This step isn’t necessary for our citizen science purposes, but can be useful for groups who would like to control for additional error and perhaps are using the testing for a science fair project. Because there can be some crossover with Nile Red stain and organic material, it's suggested for samples with a lot of sediment or algae to use a peroxide bath. Essentially, you can just allow the H2O2 to soak the sample overnight, which will dissolve a fair amount of the organic material. We suggest filtering out the water, then scraping the filtered “stuff” from the filter paper into a beaker and adding the peroxide, letting it soak, then re-filtering it using the same filter paper. You can also use a higher percentage peroxide (which would do a better job of eating away the plant material/waste) but you would need a fume hood. If you have access to one, go for it!
Are the water samples supposed to come from bodies of water or from water sources like the tap?
You can filter and stain any water you’d like! One of the first uses of the Nile Red staining method was actually developed to study microplastics in bottled water. We suggest sampling local nearby freshwater ponds/streams/lakes/rivers, but you can feel free to be creative and try out sampling things like rainwater puddles or tap water. You are most likely to see larger microplastics (that do not require a microscope) in surface water from ponds or lakes near the shore, as plastics tend to float and accumulate near shorelines.
How is this data going to be used? Will participant names be included?
At this time, the purposes are primarily for public engagement and education. The publicly available data map shows only the presence/absence results and a name if you'd like to include it (such as "Ms. Anderson's Class") and facility (i.e., "PS 130"). We will also collect an email address and contact information of at least one group member for communication purposes. In January 2021, the project will be formally surveying participants' experiences with the goal of publishing the resulting data. Participants will be notified in advance of this opportunity.