Assist.-Prof. Dr. Sarah Pati
Assistant Professor for Environmental Contaminants
☎ +43 1 4277 53311
✉ sarah.pati(at)univie.ac.at
⚲ Josef-Holaubek-Platz 2 (UZA II), Room 2C409, 1090 Vienna
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Publications Overview
Assessing and managing anthropogenic contamination of natural resources and ecosystems represents a major challenge for a sustainable global development. To improve assessment of the environmental impact of anthropogenic compounds, Sarah Pati’s group investigates the occurrence and fate of organic contaminants in aquatic systems. Our research spans from comprehensive studies at the field scale to mechanistic investigations at the molecular scale and includes both emerging and legacy contaminants as well as their transformation products. A particular focus lies on elucidating reaction mechanisms of photochemical and enzymatic transformation processes with a combination of high-resolution mass spectrometry and compound-specific stable isotope analysis.
Sarah has joined CeMESS in 2024, after appointments as research associate with a Swiss National Science Foundation Ambizione Fellowship at the University of Basel (2019-2023) and as postdoctoral researcher at the University of Minnesota (2016-2019). Sarah has received a PhD in environmental chemistry from ETH Zurich and Eawag in 2015.
Research Topics
Organic contaminant biotransformation by oxygenase enzymes
Oxygenase enzymes often initiate the microbial transformation of persistent organic chemicals in natural environments. While we have a good understanding of the substrate spectrum and catalytic cycles of these enzymes (Pati et al.), the overall importance of oxygenase enzymes for contaminant transformation in complex microbial communities (e.g., wastewater, freshwater, soil) is less investigated. One obstacle in quantifying enzymatic oxygenation reactions is the formation of unspecific transformation products, which can originate from various compounds and different reaction types. In addition, oxygenase enzymes can be inefficient in activating and incorporating O2 into their substrates, leading to the formation of reactive oxygen species (Pati et al.). Our research addresses these issues by applying a combination of stable isotope labeling, high-resolution mass spectrometry, and reactive oxygen species assays to biotransformation experiments with diverse microbial communities and various organic compounds including rubber additives.
Photochemical contaminant transformation and O2 consumption
In sunlit surface waters, photochemical processes play an important role in transforming both anthropogenic and natural organic compounds. Organic compounds can undergo direct photochemical transformation when they absorb wavelengths in the solar spectrum. In addition, indirect photochemical transformations are initiated by sunlight absorption of dissolved organic matter leading to the formation of reactive intermediates, such as reactive oxygen species, which can react with a wide range of organic compounds. To quantify the importance of photochemical processes for contaminant transformation and O2 consumption in surface waters, we conduct model laboratory experiments, determine photolysis rates (Pati & Arnold), identify photolysis products and important reactive intermediates, and quantify isotopic fractionation of organic compounds and O2 (Pati et al.).
Stable isotope analysis and high-resolution mass spectrometry
Stable isotope analysis is a powerful tool to distinguish different contamination sources of anthropogenic chemicals in the environment, identify transformation mechanisms of organic contaminants (Hofstetter et al.), and quantify net O2 consumption/production in aquatic systems. For small inorganic compounds (e.g., O2), and legacy contaminants (e.g., nitroaromatic explosives), such methods are well established and applicable to both field-scale and laboratory studies. Current methodological developments in our group focus on expanding stable isotope analysis to emerging polar contaminants (e.g., sulfonates and ionic liquids) with the use of high-resolution mass spectrometers. In addition, we employ high-resolution mass spectrometry to quantify compound mixtures in surface waters and sediments (Pati & Arnold) as well as identify transformation products in laboratory experiments.
