Traces in the Fog

Born into violence: the offspring of mixed

aggressions, traces of sickly silver

quickly infiltrate our atmosphere. Toxic

clouds that sail the zephyrs, spurting

their entrails in rhythmic pitter patter

of metallic rain that cascades upon the sea.

 

Soundscapes of forest fires and burning

waste sink beneath the waves, where

greedy microbes consume their dirty

secrets, spinning forgotten exhalations

into potent toxins that drift towards

the ocean’s soft and pallid skin.

 

Spat back into the aether, these regurgitated

mists amble purposefully towards the

shore, creeping across boundaries

on briny, poisoned breath. Probing

for opportunities to slither silently

across the mottled, broken coast.

 

Translucent blankets drape across

the land, slovenly, unwanted guests

that bring gifts of sickness and malaise.

A porous sponge that washes nosey

minks and snooping pumas with spoiled

droplets of distant ocean dew.

 

Eyes fixed downwards, we turn

our backs towards the sea, as cloyingly

the fog begins to rise. Envelopes of tainted

vapours that spread their tendrils

between the weakened chains, until

every lungful is laced with silver.

This poem is inspired by recent research, which has found that fog may be responsible for elevated levels of mercury in pumas living in coastal regions.

Mercury (also known as quicksilver) is a globally distributed pollutant found in ecosystems across the world, with natural sources of mercury including volcanic eruptions and anthropogenic (human-caused) emissions including those released from the burning of fossil fuels, or from their use in industrial processes. Unlike other metals, the atmosphere is the main pathway for mercury to be transported, and while it tends to only exist in trace amounts in the atmosphere, new research has shown that there is a pathway through which coastal terrestrial food chains may be exposed to mercury. As atmospheric mercury accumulates in the ocean via rainwater, it is converted by anaerobic bacteria (which live in the ocean’s depths) to a compound called methylmercury, the most toxic form of mercury. At high concentrations, methylmercury can cause neurological damage, and can also severely affect fertility and reproduction. Upwelling (a process in which deep, cold water rises toward the surface) brings some of this methylmercury back to the surface, where it can transfer into the atmosphere and be transported by fog; this fog then drifts inland, collecting on coastal vegetation and dripping to the ground, where the methylmercury starts to build up slowly in the food chain, in a process known as bioaccumulation.

In this new study, researchers investigated how methylmercury poisoning from coastal fog was permeating to the top of the food chain, focusing their study on pumas (also known as mountain lions or cougars) in the Santa Cruz Mountains, California, in the United States. By collecting fur and whisker samples from 94 pumas living in coastal regions, and 18 pumas living in non-coastal regions they were able to show that average mercury concentrations in the coastal samples were approximately three times that found in the non-coastal group. Furthermore, at least one puma was found to have mercury levels that were known to be toxic to species lower down the food chain like mink and otters, while two others had ‘sublethal’ levels that reduce fertility and reproductive success. Although mercury levels in fog present no health risk to humans, the risk to terrestrial mammals may be significant. With each step up the food chain, from lichen to deer to pumas, mercury concentrations can increase by at least 1,000 times, meaning that coastal environments will need to be carefully monitored as global mercury levels continue to increase as a result of anthropogenic pollution.

An audio version of this poem can be heard here: