A Watershed Approach to Measuring Microplastics and Lag Time in Surface Waters
Advances in Field Sampling, Measurement, and Sensor Technologies
Poster Presentation
Prepared by C. Simmerman
University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108, United States
Contact Information: simme090@umn.edu; 651-335-7332
ABSTRACT
The use of plastic materials has gained remarkable societal benefits for humans, but there are consequent environmental impacts that result from the human use and manipulation of plastics. Plastic debris is an environmentally persistent and complex contaminant that has permeated the aquatic environment. Microplastics are plastic debris that are less than 5 mm in size. Their small size increases the potential for these plastic particles to enter food webs. This is particularly concerning because plastics contain a plethora of chemical additives that can sorb toxic contaminants from the surrounding water such as PCBs, pesticides, and metals. This makes microplastics a potential pathway for contaminants to enter food webs, and not only harm aquatic life, but also humans who are dependent on freshwater ecosystems for drinking water and food resources. Microplastics are an emerging contaminant of concern given their ubiquitous presence and poorly understood interactions with the environment. In the literature, although highly under researched, agricultural practices such as application of sewage sludge, plastic mulching, the use of tile drainage systems, polymer coated seed, and encapsulated pesticides has been suggested to generate high amounts of plastics in the environment.
Additionally, agricultural practices can generate other concerning contaminants including excess nitrogen and phosphorous, herbicides, fungicides, and pesticides that pose threat to the quality of our water resources. Management practices are commonly put in place to reduce contaminant losses, but it is difficult to determine the amount of time it will take in order to see the effect of a given management practice at a watershed scale. Conveniently, the commonly used pre-emergent herbicide metolachlor was reformulated in 2000 from racemic to the more herbicidally active s-form, and this unique time marker can be exploited to measure residence time. Furthermore, metolachlor and nitrate are applied, infiltrated, degraded, and leached throughout the soil column simultaneously, and therefore metolachlor is a conservative tracer of nitrate in the water column.
In this study, a novel method was utilized to quantify the lag time or residence time of surface waters using a watershed scale approach. Polar Organic Compound Integrative Samplers (POCIS) were deployed in 10 subwatersheds of the agriculturally dominated Cannon River in South Eastern Minnesota every 28 days (excluding the winter months) to capture the ratio of the racemic and s-forms of metolachlor for residence time analysis. Bulk 1 L water samples were collected every 28 days at the same locations for microplastic analysis. Discovered trends and results will be discussed.
Advances in Field Sampling, Measurement, and Sensor Technologies
Poster Presentation
Prepared by C. Simmerman
University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN, 55108, United States
Contact Information: simme090@umn.edu; 651-335-7332
ABSTRACT
The use of plastic materials has gained remarkable societal benefits for humans, but there are consequent environmental impacts that result from the human use and manipulation of plastics. Plastic debris is an environmentally persistent and complex contaminant that has permeated the aquatic environment. Microplastics are plastic debris that are less than 5 mm in size. Their small size increases the potential for these plastic particles to enter food webs. This is particularly concerning because plastics contain a plethora of chemical additives that can sorb toxic contaminants from the surrounding water such as PCBs, pesticides, and metals. This makes microplastics a potential pathway for contaminants to enter food webs, and not only harm aquatic life, but also humans who are dependent on freshwater ecosystems for drinking water and food resources. Microplastics are an emerging contaminant of concern given their ubiquitous presence and poorly understood interactions with the environment. In the literature, although highly under researched, agricultural practices such as application of sewage sludge, plastic mulching, the use of tile drainage systems, polymer coated seed, and encapsulated pesticides has been suggested to generate high amounts of plastics in the environment.
Additionally, agricultural practices can generate other concerning contaminants including excess nitrogen and phosphorous, herbicides, fungicides, and pesticides that pose threat to the quality of our water resources. Management practices are commonly put in place to reduce contaminant losses, but it is difficult to determine the amount of time it will take in order to see the effect of a given management practice at a watershed scale. Conveniently, the commonly used pre-emergent herbicide metolachlor was reformulated in 2000 from racemic to the more herbicidally active s-form, and this unique time marker can be exploited to measure residence time. Furthermore, metolachlor and nitrate are applied, infiltrated, degraded, and leached throughout the soil column simultaneously, and therefore metolachlor is a conservative tracer of nitrate in the water column.
In this study, a novel method was utilized to quantify the lag time or residence time of surface waters using a watershed scale approach. Polar Organic Compound Integrative Samplers (POCIS) were deployed in 10 subwatersheds of the agriculturally dominated Cannon River in South Eastern Minnesota every 28 days (excluding the winter months) to capture the ratio of the racemic and s-forms of metolachlor for residence time analysis. Bulk 1 L water samples were collected every 28 days at the same locations for microplastic analysis. Discovered trends and results will be discussed.
