Happy Earth Day! Today serves as a reminder of the importance of environmental conservation and sustainable practices to ensure the well-being of our planet for future generations. At StellarNet, we support sustainability and preserving Earth’s precious ecosystems. This year, the Earth Day theme is Planet vs. Plastics! It highlights the critical need to address the global issue of plastic pollution. Plastics have become pervasive in our environment, from the deepest ocean trenches to the highest mountain peaks, causing harm to wildlife, ecosystems, and human health. This year’s theme emphasizes the importance of taking decisive action to reduce, reuse, and recycle plastics, as well as advocating for policies and practices that promote sustainable alternatives. Take a look at a customer application below!
Product Formulation Controls the Impact of Biofouling on Consumer Plastic Photochemical Fate in the Ocean
Taylor F. Nelson, Christopher M. Reddy, and Collin P. Ward
Published: June 16, 2021 | American Chemical Society
Abstract
The photodegradation rates of floating marine plastics govern their environmental lifetimes, but the controls on this process remain poorly understood. Photodegradation of these materials has so far been studied under ideal conditions in the absence of environmental factors such as biofouling, which may slow photochemical transformation rates through light screening. To investigate this interaction, we incubated different plastics in continuous flow seawater mesocosms to follow (i) the extent of biofilm growth on the samples and (ii) decreases in light transmittance through the samples over time. We used consumer products with high relevance (e.g., shopping bags, water bottles, and packaging materials) and with different formulations, referring to primary polymers (polyethylene (PE) and polyethylene terephthalate (PET)) and inorganic additives (titanium dioxide (TiO2)). The behavior of consumer-relevant formulations was compared to those of pure PE and PET films, revealing that the relative effects of UV- and, to a lesser extent, visible-light screening differ based on the formulation of the product. Pure PE showed greater relative UV-transmittance decreases (Δ = −34% through the entire sample, accounting for biofilm on both sides of the plastic film) than PET (Δ = −20%) and PE products with TiO2 (Δ = < −10%). Our results demonstrate that even with biofouling, photodegradation remains a highly relevant process for the fate of marine plastics. However, we expect photodegradation rates of plastics in the ocean to be slower than those measured in laboratory studies, due to light screening by biofilms, and the specific formulation of plastic products is a key determinant of the extent of this effect.
Keywords: biofilm formation, photodegradation, marine plastic debris, light screening, inorganic additives
Plastic debris in an increasingly prevalent and visible environmental pollutant, especially in the global ocean where an estimated 4.8 to 12.7 million metric tons of plastic waste enter from coastal countries per year. The ingestion of plastic particles has negative effects on marine organisms, and marine plastic debris poses other threats, including the leaching of ecotoxic organic additives and the harboring and transport of pathogens. The extent of the impacts of plastic debris comes in part from its expected persistence in the open ocean, as determined by various transport and degradation or weathering processes that occur. However, there is a lack of data on the rates and extents of plastic degradation, resulting in large deviations in reported lifetimes of marine plastic debris with little scientific evidence. This is further reflected by fate and transport models in the ocean which ignore degradation processes completely or cite lack of data for their rates.
Figure S3. Sunlight irradiance recorded at mesocosm facility. Panel a: wavelength-specific irradiance recorded at the corners of the seawater tanks (n = 4, gray dotted line), directly under the covers of the light condition side of the tanks (n = 3, green solid line), or directly under the covers of the shade condition side of the tanks (n = 3, purple dashed line). Lines show the average of the recorded spectra, and the shaded areas show the range of data recorded. Panel b: wavelength integrated values of recorded spectra in panel a, outside the tanks (gray circles), under the light conditions covers (green triangles), or under the shade conditions covers (purple inverted triangles). Irradiance was wavelength-integrated across the UV range (280–400 nm; left half) and visible range (400–750 nm; right half). Points and error bars show averages and standard deviations for each condition, respectively.
The main objective of this work was to determine the extent to which biofilms will screen incident sunlight from marine plastic surfaces across the solar UV- and visible-light spectrum. To this end, we incubated pieces of plastic consumer products in outdoor, continuous-flow seawater mesocosms to mimic biofouling in the marine water column. We used a crystal violet-based staining assay to determine the biofilm extent over time and measured the transmittance of the samples across sunlight-relevant wavelengths. We incubated the samples in either fully sunlit or shaded tanks in order to determine the effect of light exposure on the development of the biofilms. We chose two polymers which are among the most prevalent for plastic production and recovered marine plastic debris, are commonly formed into films for consumer products, and have different optical properties: polyethylene (PE) and polyethylene terephthalate (PET). We used different consumer film products primarily composed of PE or PET and containing inorganic additives and compared their behavior to additive-free PE and PET films.
…Sunlight irradiance spectra were recorded to assess the screening of light by these covers using a NISTcalibrated radiometer (StellarNet Inc. BLACK-Comet) in the early afternoon of a sunny day. Irradiance under the shaded covers was reduced by 71% and 74% when integrated across the UV- (280−400 nm) and visible- (400−750 nm) wavelength ranges, respectively, as compared to the light covers…
