Measuring Microplastic Occurrence in Agricultural Streams

Moriah Brown Author

07/28/2021 Added

32 Plays

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investigating the abundance of microplastics, and the impact that different land uses have on their concentration in freshwater streams.

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[00:00:00.900]My name is Moriah brown,
[00:00:02.460]and I will be presenting my research titled measuring microplastic occurrence
[00:00:07.350]in agricultural streams
[00:00:11.730]listed in the table of contents is what I will be going over in this
[00:00:15.120]presentation. That includes the background,
[00:00:18.480]purpose, materials and methods, results, conclusions,
[00:00:23.160]and future steps. And lastly, acknowledgements,
[00:00:30.370]what are microplastics?
[00:00:32.320]Microplastics are water insoluble polymers that are less than five millimeters
[00:00:37.270]in size.
[00:00:38.590]They're usually classified as primary or secondary microplastics.
[00:00:43.480]Primary microplastics are designed and manufactured to be small and used
[00:00:48.370]in a range of applications.
[00:00:50.620]An example of this are exfoliating beads found in hand soaps and face
[00:00:55.180]washes.
[00:00:56.830]Secondary microplastics are formed because of the breakdown of larger plastic
[00:01:01.330]products. Why should we care about this?
[00:01:05.590]Microplastic research is important because microplastics have been found in our
[00:01:10.210]environment, our food, our drinking water,
[00:01:13.450]and even our feces microplastics can also carry toxic
[00:01:18.490]toxic pollutants and high concentrations can have toxic toxic
[00:01:23.230]effects on organisms.
[00:01:29.830]Most research on microplastics,
[00:01:31.960]focus on Marine environments in urban areas.
[00:01:35.410]So the objective of this study is to investigate the abundance of
[00:01:39.580]microplastics and the impact that different land uses have on their
[00:01:43.660]concentration in freshwater streams
[00:01:51.610]sampling took place in Fremont, Mead and Lincoln,
[00:01:54.610]Nebraska along the Elkhorn river Johnson Creek and salt Creek
[00:02:00.370]Fremont and Mead's primary land use is agricultural
[00:02:05.350]while Lincoln's primary land use is suburban and urban.
[00:02:11.220]Yeah.
[00:02:16.000]Water samples were collected by grab sampling,
[00:02:19.120]using four liter bottles and with a mantra trawl net that us
[00:02:23.840]pictured on the right sediment samples are taken from the banks of each
[00:02:28.570]site in smaller 250 milliliter grab samples are
[00:02:33.160]collected for solids analysis.
[00:02:36.010]The water's temperature pH and conductivity are measured using a hand-held meter
[00:02:41.200]and nitrate, nitrite,
[00:02:42.790]and phosphate concentration remeasured using hatch test strips
[00:02:48.370]to extract microplastics from water samples.
[00:02:51.520]The samples are first sieved through the various size ranges
[00:02:57.730]and then oxidize to dissolve any organic matter.
[00:03:02.170]And a salt solution was added to the samples to allow for density separation,
[00:03:07.120]where denser particles would sink to the bottom and the less dense particles and
[00:03:11.380]microplastics will float to the top.
[00:03:15.310]The solution containing the floating microplastics is then filtered on the
[00:03:19.630]filter paper to later be counted.
[00:03:22.600]Sediment samples were dried in the oven and oxidized
[00:03:27.730]then centrifuged and filtered on the filter paper to extract the
[00:03:31.990]microplastics. And then later counted
[00:03:38.160]articles recovered from extraction are visualized using the Nikon
[00:03:42.930]S M Z 25 stereo microscope for each size
[00:03:47.580]category.
[00:03:48.660]Plastics are counted directly from the Petri dish pictured
[00:03:53.610]on the right are images taken using the stereoscope of microplastics from
[00:03:58.410]each size category.
[00:04:04.320]The results discussed in this presentation all come from our Fremont
[00:04:08.970]location, grab samples
[00:04:15.240]results of the study indicate that microplastic concentration increased
[00:04:19.800]downstream of a wastewater treatment plant outfall.
[00:04:23.400]The concentrations of microplastics in the
[00:04:26.430]63, 250 and 2000 size categories and
[00:04:31.020]microplastic fragments also increased moving downstream of the wastewater
[00:04:35.130]treatment plant,
[00:04:39.530]the distribution of microplastics and the size category showed to change while
[00:04:44.180]moving downstream,
[00:04:45.260]the wastewater treatment plant the further downstream from the wastewater
[00:04:49.190]treatment plant,
[00:04:50.300]the more evenly distributed the microplastics were in each size category.
[00:04:59.830]Preliminary data indicated a possible correlation between nitrate,
[00:05:03.990]concentration and microplastic concentration,
[00:05:07.800]but there was no correlation between microplastic concentration and total solids
[00:05:17.050]microplastics found in the Elkhorn river can come from a combination of sources
[00:05:21.940]that include wastewater treatment effluent and agricultural runoff.
[00:05:26.890]This data set is one of the first that focuses on microplastics and agricultural
[00:05:31.540]streams, future steps to continue.
[00:05:34.240]This research includes sampling and processing of samples from sites with urban
[00:05:39.190]and suburban land uses and to process more net and sediment samples.
[00:05:48.970]I would like to thank my faculty mentor, Dr.
[00:05:51.370]Shannon Bartelt-Hunt McNair scholar, Seth Caines,
[00:05:55.330]and graduate assistant and mentor Meredith Sutton for helping me with this
[00:05:59.620]project
[00:06:00.130]this summer. Funding for this project was provided in part by the national
[00:06:04.330]science foundation.

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Measuring Microplastic Occurrence in Agricultural Streams

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