Published On: July 29th, 2026

Hasti Ziaei Coauthors Paper on Mercury-Impacted Pipeline Scale in Toxics

Hasti Ziaei, PhD, coauthored the paper, “Methylation Potential of Mercury-Impacted Pipeline Scale,” which was published in the journal Toxics on July 13, 2026.

Her coauthors were Paul Bireta from Chevron Corporation and Danny Reible from Texas Tech University.

Hasti is a Professional based in New Jersey who brings experience in the water industry assessing contaminated sediment sites and effectively communicating complex investigation findings to diverse audiences. She specializes in evaluating the bioavailability, fate, and transport of heavy metals in sediment.

Toxics is an international, peer-reviewed, open-access journal on all aspects of toxic chemicals and materials. It is published monthly online by Multidisciplinary Digital Publishing Institute (MDPI).

MDPI, a scholarly open-access publisher based in Basel, Switzerland, fosters open exchange across disciplines by publishing more than 400 peer-reviewed conference journals.

Abstract: “Methylation Potential of Mercury-Impacted Pipeline Scale”

This study assessed the leachability and methylation potential of total mercury (THg) associated with internal deposits in subsea oil and gas pipeline segments that are abandoned on the seafloor. The studies were conducted for up to 28 weeks under anaerobic conditions in static microcosms in which mercury-contaminated scale was exposed directly to sediments. The scale had an XRF-measured surficial THg concentration ranging between 15 and 3000 micrograms per square centimeter (µg/cm2). Release to sediment contacting the scale was rapid with no significant changes noted in THg concentrations after 6 weeks. THg released to sediments from intact pipeline coupons with low THg (15.5–124 µg/cm2) released an average of 16 percent (%) of the THg mass present in the coupon into the sediments while those with higher THg (457–1367 µg/cm2) released an average of just 0.85% of the THg present in the coupon. Additional studies were conducted with all scale shaved into microcosms to simulate rapid and complete corrosion of the pipeline. The resulting sediment concentrations showed that the XRF-measured surficial THg accounted for all of the THg in the scale. In both sets of experiments, peak methyl mercury (MeHg) sediment concentration (measured at 8 and 12 weeks) averaged just 0.05% of the THg in the sediment. MeHg in the sediment was not correlated with the mass of THg measured in the scale and showed only a weak correlation with sediment THg suggesting that much of the THg is unavailable for release and methylation. The sediment MeHg concentration was positively correlated with leachable THg measured as filtered THg (passing 0.45 µm filter) (R2 = 0.81). The methods presented here provide a means of assessing mercury release from pipeline scale and its implications in other environments.

More Information on Mercury-Impacted Pipeline Scale and Mercury Release to Sediments

Read the paper.
Learn more about Toxics.
Learn more about MDPI.
For more information about the methylation potential of total mercury, contact Hasti at Hasti.Ziaei@Geosyntec.com.
Learn more about Hasti: Hasti Ziaei | LinkedIn