SETAC News Release
A study published in Environmental Toxicology and Chemistry underscores that the release of pollutants in one region can have implications beyond its borders; emphasizing the dire need for global collaboration on environmental issues. The study suggests that coal-burning activities in the Asia-Pacific region have influenced environmental conditions in the United States Pacific Northwest.
It is well established that concentrations of substances in sediment or ice cores as a function of depth can reveal what was present in the atmosphere in the area across a number of previous years. Given that, to evaluate the extent and source of pollutants coming into the Pacific Northwest, the researchers analyzed the concentrations of coal-related metals and metalloids in sediment layers in Deep Lake, located in northeastern Washington state. They then compared the patterns of measured concentrations in sediment to those reported by the United States Geological Survey in an ice core collected in Upper Fremont Glacier, Wyoming, in 1996.
To conduct the analysis, Washington State Department of Ecology (DOE) crew members collected two vertical sediment box cores from the bottom of Deep Lake at a water depth of 23 m (76 ft) from the lake bottom (0 cm) to a depth of 42 cm (16.5 in) in 2016. Segments of one core was dated by DOE using the Constant Rate of Supply model with 210Pb. The other core was sent to Whitman College where it was sectioned and analyzed for elements using an Inductively Coupled Plasma- Mass Spectrometry (ICP-MS), Mercury Hydride System – Flame Atomic Absorption Spectroscopy (HMS-FAAS), and Cold Vapor – Atomic Fluorescence Spectrometry (CV-AFS). Because detection limits, and thus measurement resolution, differ wildly for ice and sediment sample, the researchers compared the profiles of the chemical per depth between the sediment and ice samples and not the concentrations themselves.
The researchers found that arsenic, barium, selenium and mercury (all coal-related elements) in sedimentary deposits from Deep Lake have increased over recent years. Most notably, they showed that mercury deposition has increased by around 400-fold between 1996 and 2014, while barium, selenium and arsenic increased 956-fold, 2.4-fold and 1.3-fold respectively. This was thought to be attributed to coal burning. Lead author, Frank Dunnivant, explained that while atmospheric inputs of mercury can be natural (from volcanoes), other studies have shown human activities contribute at least 52% of mercury to the atmosphere. Further, the researchers were able suggest the original source of the metals knowing that Deep Lake and Upper Fremont Glacier receive atmospheric deposition from different atmospheric patterns. Prevailing wind patterns around Deep Lake are from Asia, while the Fremont Glacier weather patterns are considerably more to the south and east. Upon review of the weather patterns, it is suggested that these metals likely originated from coal-burning activities in the Asia-Pacific region. This is not surprising given the fact that Chinese coal consumption has quadrupled since 1975, nearly tripling from 1998 to 2013 alone, according to the National Bureau of Statistics of China. Coal-burning is known to release natural elements such as mercury, barium, selenium and arsenic to the atmosphere if stack exhaust is not captured and mitigated.
These findings emphasize the need for global cooperation to improve environmental conditions. They also show the interconnectedness of human impact. Hyper-civilization and western consumer patterns that have driven increased industrialization, without due environmental controls in some regions, are not without consequences to the west.