Changing the way we look at water
Regulations require municipal water system administrators to test the water coming out of water and wastewater treatment plants for specific chemical pollutants. When their testing shows the specific chemical pollutants are not present, the water is considered to be clean. But it turns out the treated water is sometimes not as clear of chemicals as people have thought. The rapid development of new chemicals has significantly outpaced the implementation of new water quality regulations or the evolution of new analytical techniques.
Damian Helbling, assistant professor in the School of Civil and Environmental Engineering at Cornell, is changing the way we look at water. “It is hard to find something if you don’t know what you are looking for,” says Helbling. “So we have been working on developing tools to more comprehensively assess the occurrence of new chemicals in water.” Without water, life on Earth is impossible. So having an improved sense of what is in the water we are bathing in, cooking with, and drinking is essential.
The job of identifying chemicals in water is complex. The American Chemical Society manages a database of registered chemical substances called the Chemical Abstracts Service (CAS) Registry. The CAS database grows by approximately 15,000 substances each day and now contains more than 91 million unique organic and inorganic chemical substances. It is simply not practical to develop specific tests or techniques to screen water for each and every possible chemical pollutant.
Once a chemical is used for any application, it does not simply disappear. Rather, almost every man-made chemical winds up somewhere in the environment--either in the soil, the air, or the water. Given the sheer number of chemicals being used today, environmental engineers and environmental chemists often employ models to predict where a chemical might wind up in the environment. This approach can provide guidance on what types of chemicals to look for in water. However, the process becomes much more complicated when chemicals break-down into smaller chemicals in the environment or in water and wastewater treatment plants. This is where Damian Helbling and his research partners come in.
“We are living in a chemical age. The number of chemical substances we use in our daily lives is increasing incredibly,” says Helbling. “Rather than look for these chemicals on an individual basis, we are developing high-throughput screening techniques using mass spectrometry.” Helbling’s process takes what he calls a “generalist” approach. His instrument can measure the exact mass of whatever molecules it finds in a sample of water. It can then deduce the molecular formula and, possibly, the chemical structure of chemicals present in the water.
The approach also allows Helbling’s team to study the break-down products, or metabolites, of chemical pollutants. “Environmental metabolomics is interesting and important on many levels. Studying how chemicals break-down can allow us to make better predictions on which chemicals might be degradable and under which conditions, and whether or not the transformation products are going to pose a risk.” Many existing processes in water and wastewater treatment plants were designed decades ago without consideration for new chemical pollutants. “Understanding chemical reactivity and product formation on a mechanistic level is also critical for developing new remediation strategies for these chemicals.”
Having come to Ithaca and the Finger Lakes region of New York, Helbling is in a perfect location to gather data using his technique. He has partnered with the United States Geologic Survey and the Ithaca Area Wastewater Treatment Facility to gather samples of water around Ithaca. “One of my goals is to use these screening methods we have developed to improve our understanding of the extent of occurrence of organic chemical pollutants in the waters of Tompkins County,” says Helbling. “Who knows? Maybe we’ll find the waters here are very clean. In any case, this will help us focus on specific chemicals that may be of unique concern at the local level.”
A long-term goal for Helbling is to see his work inform the chemical industry. “There is a growing awareness of ‘green’ chemistry,” says Helbling. “A lot of what we are doing can hopefully feed back into industry and shape what compounds they produce and how they are used.” By looking at water differently than we have in the past, Damian Helbling is challenging the status quo and helping to create a cleaner world.