Cave carbonate mineral deposits (speleothems) contain trace elements that are intensively investigated for their significance as palaeoclimate and environmental proxies. However, chlorine, which is abundant in marine and meteoric waters, has been overlooked as a potential palaeo-proxy, while cosmogenic 36Cl could, in principle, provide a solar irradiance proxy. Here, total Cl concentrations analysed from various speleothems were low (3–14 mg/kg), with variations linked to crystal fabrics. High-resolution synchrotron radiation micro X-ray fluorescence (μみゅー-XRF) trace element mapping showed Cl often associated with Na, Si, and Al. We propose that speleothems incorporate Cl in two fractions: (1) water soluble (e.g., fluid inclusions) and (2) water insoluble and strongly bound (e.g., associated with detrital particulates). However, disparities indicated that alternate unidentified mechanisms for Cl incorporation were present, raising important questions regarding incorporation of many trace elements into speleothems. Our first measurements of 36Cl/Cl ratios in speleothems required large samples due to low Cl concentrations, limiting the potential of 36Cl as a solar irradiance proxy. Critically, our findings highlight a knowledge gap into how Cl and other trace elements are incorporated into speleothems, how the incorporation mechanisms and final elemental concentrations are related to speleothem fabrics, and the significance this may have for how trace elements in speleothems are interpreted as palaeoclimate proxies.

In a recent article, Kunz and Mills (2021) report 10 drawn, a speo finished, turquoise blue, IIa40 beads manufactured in Venice and recovered from three late precontact sites in the Alaskan Arctic. They argue that these beads date to the fifteenth century, predating Columbus's arrival in the Americas. This conclusion is certainly in error because beads of this type were not manufactured prior to approximately AD 1560. The historical and archaeological evidence for this dating is substantial. Additionally, the elemental and radiocarbon evidence presented by Kunz and Mills (2021) supports a late sixteenth- to early seventeenth-century date for these beads.

Blair provides a thorough review of data he claims stands in opposition to our narrative concerning the origins of IIa40/Early Blue glass trade beads and their presence in arctic Alaska prior to Columbus’ initial voyage. He employs three lines of evidence: historical and archaeological data, Instrumental Neutron Activation Analysis, and radiocarbon dating. Our reply addresses his application of these data sets, clarifying his use of our data to arrive at his conclusions. While we continue to disagree with Blair, we do wish to acknowledge his time spent on debating the issue thereby furthering all of our understanding on this topic.

To evaluate the daily Se intake of 3- to 5-year-old Japanese children, we used seventy-two urine samples collected from fifty-three children (twenty-seven male and twenty-six female) from two cities in Miyagi prefecture, Japan. For measuring low Se concentrations with high precision, accuracy and rapidity in the 24-h urine samples, we developed an instrumental neutron activation analysis (INAA) method, that is without any chemical separation, using the short-lived 77mSe (t1/2 = 17·4 s) nuclide. The estimated Se intake of the fifty-three children was 51·5 (sd 30·2) µg/d (geometric mean: 42·7 µg/d). Ten subjects (three male and seven female), successfully provided 24-h urine samples over two or three consecutive days; their Se intake was 37·4 (sd 5·9) µg/d. Based on the logarithmically transformed data of these ten subjects, the ratio of intra-/inter-individual variances of usual Se intake was 16·7 (28·0/1·7) and geometric mean was 27·7 µg/d. The 5th to 95th percentile of usual Se intake of these ten subjects was 17·5 to 40·4 µg/d, which ranged between the recommended dietary allowance and tolerable upper intake level of Se by the Dietary Reference Intakes for Japanese (2015).

Pottery production in Formative Period Mesoamerica appears to have been organised at the household level, but its distribution also provides evidence of political or economic boundaries. One distinctive ware from the Valley of Puebla, Tlaquexpa Red, used for the manufacture of sub-hemispherical bowls, was analysed by instrumental neutron activation analysis. The results indicated that many of these vessels were being made by families at Tlaquexpa itself, but that some of their products were being traded to other communities, including the nearby civic-ceremonial centre of Xochiltenango. The study gives new insight into the role of pottery production in pre-Hispanic households.