Science Direct has an abstract of an article (which folks can get the full version of if they have the right access, of course) as follows:
We report a record of atmospheric Pb deposition at a coastal site in western Iceland that spans the last two millennia. The elemental concentrations of Pb, Al, Li and Ti are determined using ICP-MS from a sediment monolith collected from a salt marsh. Multicollector (MC) ICP-MS analysis is used to obtain isotopic ratios of stable Pb. The Pb/Ti and Pb/Li ratios are used to separate natural Pb background concentrations from Pb derived from remote anthropogenic sources. The pollution record in western Iceland is subdued in comparison with Pb records from the European mainland, but the isotopic character, profile and timing of Pb deposition show good agreement with the atmospheric Pb fall-out reported from sites in Scandinavia and northwestern Europe. At the bottom of the sequence we isolate a low-level (0.1–0.4 mg kg- 1) Pb enrichment signal dated to AD 50–150. The isotopic signature and timing of this signal suggest Roman metal working industries as the source. In the subsequent millennium there was no significant or very low (i.e. elemental concentrations < 0.01 mg kg- 1) anthropogenic Pb deposition at the site up to, and including, the early Medieval period. Above a pumice layer, dated to AD 1226–1227, a small increase in Pb deposition is found. This trend is maintained until a more substantive and progressive increase is signalled during the late 1700s and early 1800s. This is followed by a substantial enrichment signal in the sediments (> 3.0 mg kg- 1) that is interpreted as derived from industrial coal burning and metal working during the 19th and 20th centuries in northern Europe. During the late 20th century, significant fall-out from European fuel additives reached Iceland.
Miller-McCune Magazine’s blog adds a bit of detail (inter alia):
An isolated salt marsh on the coast of contemporary Iceland is the last place most people would think of looking for Roman-era air pollution. But traces of atmospheric lead pollution found in the sedimentary cores of an Iceland salt marsh, most likely originated from first- and second-century C.E. Roman mining and metal-working operations, a new study reports. The research, which appeared in the April 1 issue of the journal Science of the Total Environment, indicates that the lead most likely found its way aloft from what is now Somerset in Britain. William Marshall, a research fellow in geoscience at the University of Plymouth in the U.K., and the paper’s lead author, says it’s the most distantly detected example of such Roman atmospheric pollution from Britain. Previous evidence of Roman-era atmospheric lead pollution has been found in peat deposits in Europe, in sediments from Swedish lakes and in ice cores from Greenland.
Passing over the unintended non-pun in the phrase ‘lead author’, the item is interesting, if true, but I don’t understand why there would be no similar ‘Roman Pollution’ between 150 and 1226. It’s not as if Roman (or other) metalworking in Britain (or elsewhere) stopped during this period. I can’t help but wonder whether the lead detected here might be connected to say, the eruption of Vesuvius vel simm..