Human-made chemicals found throughout ocean environments
Co-Authors Andreas Haas (NIOZ Netherlands) and Craig Nelson (University of Hawaiʻi at Mānoa) taking water samples at the coast of Mo'orea (French Polynesia).
An analysis of more than 2,300 seawater samples from more than 20 field studies around the globe indicates that human-made chemicals — from plastic additives and industrial lubricants to pharmaceuticals and pesticides — are widespread in the marine environment, particularly in coastal and estuarine waters. The study, led by biochemists at the University of California, Riverside and co-authored by University of Hawai‘i at Mānoa oceanographers, represents one of the most comprehensive chemical analyses of coastal oceans to date.
The international research team analyzed seawater samples collected over a decade from coastal regions from the Pacific, Atlantic, and Indian Oceans. Reported in Nature Geoscience, the findings show that industrial chemicals, many of which are rarely monitored, are far more abundant and widespread than previously recognized.
“As part of this study we included samples from coral reefs across both the Pacific and Caribbean, including samples throughout Hawaiian and Tahitian ecosystems, and we were struck by how widespread things like pharmaceuticals, pesticides and plastics were even in some remote island reefs and dozens of kilometers offshore,” said Craig Nelson, researcher in the UH Mānoa School of Ocean and Earth Science and Technology, Graduate Chair of Oceanography, and one of the senior authors on the paper.
“Even in places we consider relatively pristine, we found clear chemical fingerprints of human activity,” said Daniel Petras, assistant professor of biochemistry at University of California, Riverside (UCR) who co-led the study with Jarmo Kalinski. “The extent of this influence was surprising.”
Impacts nearshore and offshore
The study found that in datasets from coastal environments as much as 20% of the measured organic material was of human origin, compared to about 0.5% in the open ocean. In extreme cases, such as river mouths impacted by untreated or poorly treated wastewater, that figure exceeded 50%. Across all samples, the 248 identified human-derived compounds tracked in this study made up a median of ~2% of the total detected signal.
While pesticides and pharmaceuticals were expected to be most concentrated near shorelines, the study found that industrial compounds, including substances used in plastics, lubricants, and consumer products, dominate the anthropogenic chemical signal in all areas of the ocean.
The researchers also found that anthropogenic chemicals persist well beyond the coastline. Even more than 20 kilometers offshore, human-derived compounds accounted for roughly 1% of detected organic matter.
Advancements in lab and computational methods
A key innovation the research team used was the combination of consistent, high-resolution mass spectrometry methods across multiple laboratories, as well as the use of scalable computational tools developed by Mingxun Wang, an assistant professor in computer science at UCR. All data from the study are publicly available, allowing other researchers to reanalyze the results or integrate new datasets as they emerge, an important philosophical shift in applying these new methods.
“Many anthropogenic chemicals that are contaminating marine systems can rapidly decrease organismal and microbial community functioning,” said Zachary Quinlan, co-author and research biologist at the Hawai‘i Institute of Marine Biology in SOEST, and one of the early developers applying these modern untargeted chemical analyses to marine ecosystems. “What our data suggests is that the spread of anthropogenic contaminants and their impacts may be far larger than previously thought.”
Despite the size of the dataset, the researchers note that large parts of the world remain understudied. Further, the effects of the cumulative chemical concentrations and their long-term ecological impacts remain largely unknown.
“The absence of data doesn’t mean the problem isn’t there,” Kalinski said. “It means we haven’t looked closely enough yet.”
Read also on Phys.org, UC Riverside News, and UH News.