Emily Chan
So, they examined a sediment core from an upwelling area in Vietnam in the eastern South China Sea. Upwelling areas are coastal regions where cold, nutrient-rich water rises up from the sea floor, replenishing surface ecosystems.
The core was divided into two sections. At the base of the core, which dates back to around 1200 B.C., up to about three inches from the top, silver concentrations decreased. But, the upper end of the core contrasted greatly.
Over the past 3,200 years, silver concentrations showed a sudden increase around the year 1850. The timing coincides with the increase in carbon dioxide emissions, suggesting that climate change speeds up the burial of silver in some marine sediments.
In upwelling areas, silver concentrations are generally high, especially when they’re near industrial sites, where humans add more silver through pollution.
Among these sites are coastal Massachusetts and the San Francisco Bay. Previously, researchers dubbed the bay as a “silver estuary.”
Off the coast of Vietnam, silver levels are naturally high. They were similar to levels that were recorded in upwelling areas from Mexico, Canada, Peru, and Chile. Global warming can elevate water temperatures and create stronger coastal winds.
This combination intensifies upwelling, so more nutrients are rising to the surface and leading to higher levels of dissolved silver.
The organisms in those regions absorb the silver. When they die and sink to the sea floor, the silver drops down with them. Low oxygen levels may also be boosting silver concentrations in sediments.
The abundance of silver could be an issue if it’s happening worldwide. The high levels of silver might get released into the water and poison ocean ecosystems or find their way to land.
The study was published in Geophysical Research Letters.
