About

John Mak is a Professor of Atmospheric Sciences at Stony Brook University, with a research focus on atmospheric chemistry, trace gas isotopic composition, and the development of instrumentation for atmospheric research. His work includes studying the reconstruction of paleo-atmospheric chemistry through trace gas isotopic ratios, analyzing trace gas emissions from the biosphere, and developing research aircraft instrumentation platforms. Mak's recent projects involve examining the impact of the COVID-19 pandemic shutdown on regional chemistry in the New York City area, utilizing high-resolution mass spectrometry to observe volatile organic compounds and their variations driven by anthropogenic and biogenic emissions. He is the lead PI of NSF-funded collaborative projects such as GOTHAAM, which aims to investigate trace gases, halogens, and aerosols using airborne missions supported by research aircraft. His research also includes quantifying isotopologues of atmospheric carbon monoxide, exploring mineral dust and sea salt aerosol mechanisms for methane removal, and analyzing paleo-CO records from ice cores to understand historical atmospheric conditions. Mak's contributions extend to developing analytical techniques for measuring isotopes in ice cores, participating in field studies like the Southeast Atmosphere Study, and publishing findings on boundary layer turbulence and urban aerosol dynamics. His work is supported by agencies including NSF, EPA, and NOAA, and he collaborates with multiple universities and research institutions to advance understanding of atmospheric processes and their implications for climate and air quality.

Research topics

• Organic chemistry
• Chemistry
• Environmental chemistry
• Chromatography
• Environmental science
• Geography
• Meteorology
• Atmospheric sciences

Selected publications

• Using stable isotope of measurements of carbon monoxide for constraining short- and long-term changes in its global budget and atmospheric chemistry

  2026-03-14

  articleOpen access

  Carbon monoxide (CO) is an important indirect greenhouse gas, plays a key intermediate role in the cycling of carbon compounds in the atmosphere and via these reactions affects the atmospheric oxidation capacity. Its sources and sinks can be (partially) distinguished with isotope measurements, but extensive observations of CO isotopic composition are sparse. A network of independent global observatories monitored 𝛿13CCO and 𝛿 18OCO at the turn of the 21st century. Since this time, the sole continuous monitoring of CO isotopic composition has been carried out at Baring Head, New Zealand. Starting in 2023, as part of the ISAMO project, we have resumed regular measurements of 𝛿13CCO and 𝛿 18OCO at seven global monitoring stations, with a focus on the tropical Atlantic. The goal of ISAMO is to better constrain the proposed pathway of methane removal via chlorine radicals that can be released photochemically from mixed mineral dust - salt aerosols. Here we use the new and existing CO isotope data together with model simulations to derive empirical constraints for the production rate of CO from the CH4 + Cl reaction. In addition, we will demonstrate how CO isotope measurements can be used to constrain long-term, and episodic, changes in the global and regional CO budget, arguing for sustaining such measurements at globally distributed locations.

  PublisherDOI

• Recommendations for the NSF Facilities for Atmospheric Research and Education (FARE): Access and Capabilities

  Bulletin of the American Meteorological Society · 2025-03-03

  articleOpen access

  Abstract Recommendations are presented regarding the composition and accessibility of the Facilities for Atmospheric Research and Education (FARE), funded by the U.S. National Science Foundation (NSF). The FARE program broadens access to specialized facilities including research aircraft, advanced instrumentation, laboratories, and field support services to enable observationally focused atmospheric research. The FARE program includes the long-established Lower Atmosphere Observing Facilities (LAOF) and the more recent Community Instruments and Facilities (CIF). The recommendations presented herein result from a 2023 NSF-sponsored FARE Users Workshop that addressed FARE’s accessibility and future. Significance Statement The Facilities for Atmospheric Research and Education program, supported by the National Science Foundation, provides access to a variety of instruments, platforms, and support services for experimental atmospheric research. In fall 2023, a NSF-sponsored workshop was held to raise awareness, facilitate access, and discuss the future of this resource. This report summarizes the workshop and presents its recommendations.

  PublisherOA PDFDOI

• Emerging drivers of urban aerosol increase global change vulnerability in a US megacity

  npj Climate and Atmospheric Science · 2025-09-30

  articleOpen access

  Abstract Urban aerosol pollution is evolving rapidly with global change and poses significant risks to public health. Measurements and machine learning-enabled chemical analysis of aerosol from a suburb of New York City in 2023 reveal emerging sources and drivers in a modern megacity. Regional wildfire smoke averaged 25% of organic aerosol (OA) mass and drove variability via enhancements of biogenic OA formation within smoke plumes. This biogenic OA contributed 40% of aerosol mass. Urban heatwaves enhanced both biogenic and anthropogenic sources, with ~20% of OA mass exhibiting significant heatwave sensitivity. For the first time, volatile chemical product (VCP) compounds were directly observed, speciated, and characterized in urban aerosol. Contributions to total OA averaged 15%, double the contribution from traffic. Together, this work identifies wildfire smoke, biogenic emissions, heat, and emerging anthropogenic emissions as critical global change vulnerabilities for North American urban aerosol pollution that pose unique challenges for control strategies.

  PublisherOA PDFDOI

• Identifying and correcting interferences to PTR-ToF-MS measurements of isoprene and other urban volatile organic compounds

  Atmospheric measurement techniques · 2024 · 67 citations

  • Chemistry
  • Environmental chemistry
  • Environmental science

  Abstract. Proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) is a technique commonly used to measure ambient volatile organic compounds (VOCs) in urban, rural, and remote environments. PTR-ToF-MS is known to produce artifacts from ion fragmentation, which complicates the interpretation and quantification of key atmospheric VOCs. This study evaluates the extent to which fragmentation and other ionization processes impact urban measurements of the PTR-ToF-MS ions typically assigned to isoprene (m/z 69, C5H8H+), acetaldehyde (m/z 45, CH3CHO+), and benzene (m/z 79, C6H6H+). Interferences from fragmentation are identified using gas chromatography (GC) pre-separation, and the impact of these interferences is quantified using ground-based and airborne measurements in a number of US cities, including Las Vegas, Los Angeles, New York City, and Detroit. In urban regions with low biogenic isoprene emissions (e.g., Las Vegas), fragmentation from higher-carbon aldehydes and cycloalkanes emitted from anthropogenic sources may contribute to m/z 69 by as much as 50 % during the day, while the majority of the signal at m/z 69 is attributed to fragmentation during the night. Interferences are a higher fraction of m/z 69 during airborne studies, which likely results from differences in the reactivity between isoprene and the interfering species along with the subsequent changes to the VOC mixture at higher altitudes. For other PTR masses, including m/z 45 and m/z 79, interferences are observed due to fragmentation and O2+ ionization of VOCs typically used in solvents, which are becoming a more important source of anthropogenic VOCs in urban areas. We present methods to correct these interferences, which provide better agreement with GC measurements of isomer-specific molecules. These observations show the utility of deploying GC pre-separation for the interpretation PTR-ToF-MS spectra.

  PublisherDOI

• Supplementary Fig. 3 from Antitumor Activity of a Kinesin Inhibitor

  2023-03-30

  preprintOpen access

  Supplementary Fig. 3 from Antitumor Activity of a Kinesin Inhibitor

  PublisherOA PDFDOI

• Legends to Supplementary Figures from Antitumor Activity of a Kinesin Inhibitor

  2023-03-30

  preprintOpen access

  Legends to Supplementary Figures from Antitumor Activity of a Kinesin Inhibitor

  PublisherOA PDFDOI

• Supplementary Fig. 3 from Antitumor Activity of a Kinesin Inhibitor

  2023-03-30

  preprintOpen access

  Supplementary Fig. 3 from Antitumor Activity of a Kinesin Inhibitor

  PublisherDOI

• Supplementary Fig. 2 from Antitumor Activity of a Kinesin Inhibitor

  2023-03-30

  preprintOpen access

  Supplementary Fig. 2 from Antitumor Activity of a Kinesin Inhibitor

  PublisherOA PDFDOI

• Supplementary Fig. 1 from Antitumor Activity of a Kinesin Inhibitor

  2023-03-30

  preprintOpen access

  Supplementary Fig. 1 from Antitumor Activity of a Kinesin Inhibitor

  PublisherOA PDFDOI

• Supplementary Fig. 1 from Antitumor Activity of a Kinesin Inhibitor

  2023-03-30

  preprintOpen access

  Supplementary Fig. 1 from Antitumor Activity of a Kinesin Inhibitor

  PublisherDOI

Recent grants

• Application of the Isotopes of Carbon Monoxide as Tracers of Current OH Trends and Preindustrial CO Chemistry

  NSF · $798k · 2007–2012

• The Chemistry and Sources of Carbon Monoxide in Present and Past Atmospheres

  NSF · $753k · 2011–2015

Frequent coauthors

• Alex Guenther

  University of California, Irvine

  13 shared

• Armin Wisthaler

  University of Oslo

  11 shared

• Keyhong Park

  Korea Polar Research Institute

  11 shared

• Roman Sakowicz

  10 shared

• Jeffrey T. Finer

  10 shared

• Stéphanie Roth

  Temple University

  10 shared

• Christophe Béraud

  10 shared

• Paul Gonzales

  Translational Genomics Research Institute

  10 shared

Labs

• Mak LabPI