I’m probably not supposed to admit to it quite so freely, but history is an exercise in storytelling. I revel in writing and in crafting narrative. I’m not especially adept at either, but these creative aspects of my discipline hold me captive and bring me considerable pleasure. The best days consist of uninterrupted time to write. Some of those days are good days. The writing comes smoothly, the ideas are sound, and the arguments develop flawlessly and almost on their own. Other days, writing is a struggle. Words, sentences, mental images, arguments get lost or muddled. Interesting material becomes dry and tangential.
Recently, I’ve been trying to breathe life into mercury’s biogeochemical cycle, the manner in which it circulates through the physical environment. While mercury possesses beguiling characteristics and flows across so much modern environmental history in its capacity as a pollutant and poison, my efforts to make its independent motility interesting (distinct from the fascinating debates in human science and politics) have been less successful. After spending almost a week hammering out three or four pages that described the steps of mercury’s biogeochemical cycle and how we should also start to think about an anthropogenic cycle for mercury, derived from human activities moving mercury around the planet, I became frustrated with just how bored I was. And if I was bored with a topic I found inherently stimulating, this couldn’t be a good sign. From multiple pages and extensive notes, I cut my description down to the following (still a bit rough):
It might suffice to assert that mercury has a natural biogeochemical flow. It goes up into the atmosphere and returns to the surface, where it shuffles around the lithosphere and biosphere, before evaporating again and rising up into the atmosphere in perpetual, independent, and agonizingly slow cycle. Sometimes it returns to the earth’s sediment, replaced in the cycle by mercury loosed from the same source; this cycle can take centuries or millennia. Over the past 2000 years (and especially in the last 200) human activities—primarily digging holes in the ground and burning things—have dramatically increased the amount of mercury in circulation.
Mercury’s biogeochemical cycle is. Since mercury first iterated itself, it always was. This would be of little consequence to human history but for the role humans have played in augmenting the amount of mercury cycling through the environment and its concomitant effect on human health as it bioaccumulates up the food chain. As mercury cycles through the environment, it moves not just through inanimate matter, but also through living organisms. As organisms are eaten by bigger organisms, the mercury increases in concentration at every step. In aquatic systems, phytoplankton are eaten by zooplankton, who are eaten by fish, who are eaten by bigger fish, who find their way into the human diet. On land, the process of biomagnification traces a similar route through plants, birds, and mammals to the top of the food chain. Us.