September 5, 2008


Aqueducts are kind of a pain in the ass. Although I can figure out where their sources were that fed Rome and I can see where in Rome the aqueducts emptied out (at baths and latrines, for example), that doesn't help me figure out which aqueducts my Romans might have drawn their water from. This is important because strontium isotope ratios are affected by local groundwater. If the Romans were getting water from another region with a different Sr isotope ratio or if they were eating a lot of imported grain, my Sr measurements from teeth are complicated.

As it stands, I might have some immigrants in my first run of 35 samples. 3 of them didn't work - my errors are too high, and one is just full of rubidium (because I screwed up the extraction process on that sample). But that still means that 30 human samples and 2 animal samples worked. Poking around geology article databases found me a paper that spells out the Sr isotope ranges for the volcanic mess around Rome, mostly in the Alban Hills. There were a couple aqueducts that came from that direction, but others came from directly east. The Sr from the volcanic soils ranges from around .709 to .711 (ish). Most of my Romans (and both of my animals) were in that range. However, I do have 8 people under .709 for their Sr. The question is, what's the cut-off? Does .708959 make someone an immigrant, or does it reflect mixing of the Sr content of, say, water and grain?

I'm gonna do a bit more poking this weekend as I try to draw up an abstract for AAPA and another one for SAA, and then I'll discuss my thoughts with the geochemist on Monday. If I can find an area outside of Rome with a .708 Sr content, perhaps that will help my immigrant case. But I'm hopeful that some of the lower .708 values mean something. For what it's worth, those individuals seem to be mature men and women (men ranging from 20-50, women from 40-60). So this could be interesting.


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