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Weiss-Penzias LabMicrobiology and Environmental Toxicology University of California, Santa Cruz
Introduction
Introduction
Mercury (Hg) is a globally distributed pollutant that poses serious environmental and health risks, particularly in its methylated forms, which are potent neurotoxins. These forms bioaccumulate in food webs, impacting not only human health through neurological, cardiovascular, and developmental effects, but also the reproduction and survival of fish, birds, and mammals.
Because atmospheric mercury has a long lifetime, it can travel far from its emission sources, leading to both local and global consequences. Sources include both natural and anthropogenic activity, such as volcanic eruptions, microbial methylation, and industrial processes like coal combustion.
Mercury exists in several forms in the atmosphere. Elemental mercury (Hg⁰) can be oxidized by halogen radicals (Cl∙, Br∙) to form gaseous oxidized mercury and particulate mercury (PHg). Phg forms when mercury binds to airborne particles such as sea salt or dust. These processes are key to understanding mercury deposition and bioavailability in coastal environments like Monterey Bay.
Tisch Environmental 5170 MFC TSP Sampler
Methods and Materials
Methods and Materials
Sampling:
Marine aerosol samples were collected at the UC Santa Cruz Coastal Campus, located along the Monterey Bay, from February to May 2025. Sampling was conducted weekly using a Tisch Environmental 5170 MFC TSP Sampler equipped with quartz fiber filters. This location was selected to investigate levels of PHg in a relatively unpolluted, marine-influenced environment.
Sample Preparation:
Collected filters were subjected to chemical digestion using bromine monochloride (BrCl), which converts all mercury species to elemental mercury (Hg⁰), ensuring total mercury recovery regardless of initial speciation. The digestion process included controlled redox conditions to facilitate complete conversion and minimize losses or transformation during preparation.
Analysis:
Mercury concentrations were quantified using a Tekran 2600 Cold Vapor Atomic Fluorescence Spectrometry (CVAFS) system. Calibration was performed with certified Hg standards, and quality control measures included filter blanks, duplicates, and calibration tests to ensure accuracy and reproducibility.
Results
Results
PHg concentrations in aerosols collected off the Monterey Bay were relatively low, averaging 4.23 pg/m³. This aligns with expectations for a clean, coastal site with limited local industrial influence.
When compared to industrial coastal regions such as the Yellow and Bohai Seas where average spring PHg concentrations reach and average of 61.78 pg/m³, Monterey Bay presents significantly lower levels of atmospheric mercury (Mo et al., 2025). These initial findings suggest that regional anthropogenic activity plays a substantial role in elevating PHg concentrations, while background marine environments such as Monterey Bay exhibit baseline levels influenced by long-range transport and natural cycling.
Discussion
Discussion
PHg concentrations measured off the coast of Monterey Bay were found to be relatively low, consistent with the region's characterization as a clean, low-industrial coastal environment. These baseline levels offer important insight into natural atmospheric mercury dynamics in marine-influenced systems, where anthropogenic input is minimal.
In comparison, heavily industrialized coastal areas such as the Yellow and Bohai Seas report significantly higher PHg concentrations, averaging 61.78 pg/m³ during the spring season (Mo et al., 2025). This disparity highlights the role of local emissions sources such as coal combustion, petrochemical industries, and maritime traffic in elevating atmospheric mercury levels.
Although this study was limited to late winter and spring, mercury concentrations in the atmosphere are known to fluctuate seasonally due to changes in meteorology, photochemistry, and source strength. Wind patterns, ocean-atmosphere exchange, and halogen radical availability can influence mercury oxidation rates and particulate attachment, affecting PHg formation and transport.
Future work should involve methylmercury (MeHg) speciation to assess the bioavailable fraction of mercury, as well as year-round sampling to investigate seasonal trends. A more complete temporal dataset will help distinguish between natural variability and broader environmental changes, and further clarify the impact of long-range atmospheric transport on coastal mercury deposition.
References
Si, L.; Ariya, P.A. Recent Advances in Atmospheric Chemistry of Mercury. Atmosphere 2018, 9, 76. https://doi.org/10.3390/atmos9020076
Mo, Bing, Yan Wang, Xixi Chong, Ruhai Liu, Wen Zheng, Xuyuan Zhou, Dongting Li, Xue Ding, Xianxiang Luo, and Fengmin Li. “Spatial and Temporal Distribution, Species, and Potential Source Analysis of Atmospheric Particulate Mercury in the Yellow and Bohai Seas.” Atmospheric Environment 343 (February 15, 2025): 121019. https://doi.org/10.1016/j.atmosenv.2024.121019.
Contact:
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Adknowledgments
Adknowledgments
Peter Weiss-Penzias
Carl Lamborg
Adina Paytan
Orion Moore
Lulu Mcclellan
Maria Moore
Evie Coulson
Andreas Breitenbach
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