March 30, 2019
According to a one-of-a-kind study, honey bees might be the key to helping cities monitor pollution and pinpointing the precise sources of pollutants like lead. This study, which was published via the journal Nature Sustainability, analyzed honey samples from urban hives stationed in six metro neighborhoods in Vancouver, Canada. The team of researchers behind the study tested the samples for minuscule amounts of zinc, copper, lead, and similar elements while also performing lead isotope analyses—like that of fingerprinting—to find out where these lead sources originated.
"The good news is that the chemical composition of honey in Vancouver reflects its environment and is extremely clean," Kate Smith, a PhD candidate with Canada’s University of British Columbia, said. "We also found that the concentration of elements increased the closer you got to downtown Vancouver, and by fingerprinting the lead, we can tell it largely comes from manmade sources."
The honey from Vancouver was determined to be considerably below the global average for lead and similar heavy metals, and one adult would need to consume over 600 grams (two cups) of honey each day to surpass tolerable levels, per Smith’s team. They found that this element concentration grew in areas with increased urban density, higher traffic levels, and industrial activities like shipping ports. Other Canadian cities like Delta showed increased manganese levels, which may be the result of pesticide use and agricultural activity in that area.
The team also compared their honey samples’ lead fingerprints to those of environmental samples, such as lichen, from other British Columbian areas, rocks from the Garibaldi volcanic belt, trees from Stanley Park, and sediment from Fraser River. They discovered the honey’s lead fingerprint analyses didn’t match any naturally-occurring local lead. However, the Stanley Park trees and the downtown honey samples displayed striking similarities, which pointed to possible manmade lead sources.
"We found they both had fingerprints similar to aerosols, ores, and coals from large Asian cities," Dominique Weis, the study’s senior author, said. "Given that more than 70 percent of cargo ships entering the Port of Vancouver originate from Asian ports, it is possible they are one source contributing to elevated lead levels in downtown Vancouver." Honey can provide such localized environmental "snapshots," because bees often forage for nectar and pollen inside of a two- to three-kilometer radius from their colonies.
"Honey sampling can easily be performed by citizen scientists in other urban centers, even if they lack other environmental monitoring capabilities," Smith said. The team plans to continue studying honey analysis and how it could complement traditional soil and air monitoring techniques as well as testing the effectiveness of honey analysis as an ecological monitor for other cities.
Photo By JamesWheeler