August 26, 2019 by Megan Hanks
UMBC’s Lee Blaney and research partners have published a landmark study on contaminants of emerging concern in the Chesapeake Bay. Their article in Science of the Total Environment is the first research study that quantifies concentrations of antibiotics, estrogenic hormones, and UV-filters in multiple locations of the Bay.
Blaney, an associate professor of chemical, biochemical, and environmental engineering, conducted the research with Ke He, Ph.D ‘17, chemical engineering, and Ethan Hain ‘21, chemical engineering. They also partnered with collaborators at the U.S. Forest Service and the Maryland Department of Natural Resources.
Underway since 2016, their work highlights the importance of understanding how previously unexamined chemicals impact the environment. The project has been primarily funded by Maryland Sea Grant through a Program Development Fund to Blaney, and a Graduate Research Fellowship to Hain.
The researchers studied the prevalence of contaminants of emerging concern in water, sediment, and oyster tissue collected from the Eastern Shore of the Chesapeake Bay. Their study of how accumulated UV-filters negatively impact the environment is the first of its kind. UV-filters are one of the primary ingredients in personal care products, such as sunscreen and cosmetics. The accumulation of these UV-filters can impact organisms and animals.
Analytical Chemistry
To analyze tiny amounts of liquids, scientists often use devices called microfluidic chips, which are small pieces of plastic that are etched or molded with miniscule channels. Although these single-use chips are small, their widespread use in labs, hospitals and point-of-care situations adds up to a lot of plastic pollution. Therefore, researchers reporting in ACS’ journal Analytical Chemistry have developed versatile microfluidic chips made of a renewable, biodegradable and inexpensive resource –– wood.
Microfluidic chips are useful for analyzing small samples, like a single drop of blood, at low cost because only miniscule amounts of expensive reagents are needed. When a fluid flows through the microchannels, it is mixed with certain substances and then analyzed, for example, for the presence of microbes or disease-related proteins. Recently, scientists have tried making microfluidic chips from inexpensive, environmentally friendly resources such as cloth or paper, but these devices are typically limited to relatively simple applications. Govind Rao and colleagues wanted to make a microfluidic device out of low-cost wood that could be used for a variety of purposes.
To make their device, the researchers used a laser printer to engrave tiny channels into birch plywood chips. Then, to prevent liquids from seeping into the porous wood, they coated the channels with a thin layer of Teflon™. When they introduced blue and red food dyes to the tips of Y- and T-shaped patterns of channels, the liquids mixed as efficiently in the wood chips as in conventional plastic devices. The researchers also used the wood chips, in conjunction with a fluorescence technique, to measure the amounts of two proteins and live bacteria, all of which were similar to the amounts determined by a plastic chip. The wood devices were 10–100 times less expensive than comparable plastic ones and more environmentally friendly. Now, the researchers are working on finding a renewable replacement, such as beeswax or natural oils, for the Teflon™ coating.
The authors acknowledge funding from the Defense Advanced Research Projects Agency (DARPA) and the UMBC Technology Catalyst Fund.
Note: ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies.
Image: Wood microfluidic devices could analyze small amounts of liquids in a more environmentally friendly way. Credit: Adapted from Analytical Chemistry2019, DOI: 10.1021/acs.analchem.9b01232
Mustafa Al-Adhami, David Burgenson, and Benjamin Punshon-Smith won first place in the VentureWell Idea Competition. Read more about their project idea here.
]]>Photolytic fate of organo-selenium and -tin compounds in natural and engineered water systems
Friday, May 24th at 11:00 am
Organometallic compounds are broadly classified as chemicals that include a metal atom covalently bound to a carbon atom. Due to the presence of the organic moiety and the metal atom, these chemicals participate in unique sorption, redox, and catalysis reactions. As a result, organometallics are widely applied in the biomedical, agricultural, and electrical fields as antibiotics, chemotherapy agents, antioxidants, pesticides, and semiconductors. The growing demand for organometallic chemicals may proportionally increase the environmental loading of these contaminants. Unlike conventional organic compounds, the special properties of organometallics pose distinct environmental concerns and suggest interesting environmental chemistry. Some of these compounds are transformed in the environment through mechanisms that release the inorganic metal, which is often more toxic than the organometallic chemical. Photochemical oxidation is a major abiotic process that governs the fate of organic contaminants in natural water; however, few studies have elucidated the photochemical transformation of organometallics in natural and engineered (i.e., 254 nm) and systems. The factors that control the phototransformation kinetics of different organometallics are currently unknown. This dissertation will, therefore, identify (i) quantum yields for direct photolysis of organometallics, in particular, organo-selenium and -tin compounds, (ii) second-order rate constants for organometallic reaction with reactive species (e.g., singlet oxygen (1O2), hydroxyl radicals (•OH), and triplet state dissolved organic matter (3DOM*)), (iii) the effects of water quality (e.g., pH, temperature, ionic strength, and DOM) on phototransformation, and (iv) the primary organometallic photoproducts formed through direct and indirect photolysis mechanisms.