Lilian Skytte

The distribution of mercury and other trace elements in the bones of two human individuals from medieval Denmark – the chemical life history hypothesis

Excavating human skeletons is the closest archaeologists can get to the people who lived in the past. Once excavated the bones are often analysed chemically in order to yield as much information as possible. Most archaeometric analyses performed on samples of human skeletal remains have been performed on a single sample from a tooth or a long bone. In this paper we investigate how a suite of elements (Mg, Al, Ca, Mn, Fe, Zn, As, Sr, Ba, Hg and Pb) are distributed in two medieval skeletons excavated at the laymen cemetery at the Franciscan Friary in Svendborg, Denmark.The analyses have been performed using CV-AAS for Hg and ICP-MS for the rest of the elements. We find that in general Hg concentrations are highest in the trabecular tissues and in the abdomen region. Our data also show that the elements Al, Fe and Mn concentrate in the trabecular tissue and on the surfaces of the bones. The two individuals can be clearly distinguished by Principal Component Analysis of all the measured trace elements.Our data support a previously published hypothesis that the elemental ratios Sr/Ca, Ba/Ca and Mg/Ca are indicative of provenance. Aluminium, Fe and Mn can be attributed to various forms of diagenesis, while Hg is not present in sufficiently large amounts in the surrounding soil to allow diagenesis to explain the high Hg values in the trabecular tissue. Instead we propose that Hg must originate from decomposed soft tissue.

Sampling strategy and analysis of trace element concentrations by inductively coupled plasma mass spectrometry on medieval human bones – the concept of chemical life history

RATIONALE Medieval human bones have the potential to reveal diet, mobility and treatment of diseases in the past. During the last two decades trace element chemistry has been used extensively in archaeometric investigations revealing such data. Many studies have reported the trace element inventory in only one sample from each skeleton - usually from the femur or a tooth. It cannot a priori be assumed that all bones or teeth in a skeleton will have the same trace element concentrations. METHODS Six different bone and teeth samples from each individual were carefully decontaminated by mechanical means. Following dissolution of ca. 20 mg sample in nitric acid and hydrogen peroxide the assays were performed using inductively coupled plasma mass spectrometry (ICPMS) with quadropole detection. We describe the precise sampling technique as well as the analytical methods and parameters used for the ICPMS analysis. RESULTS The places of sampling in the human skeleton did exhibit varying trace element concentrations. Although the samples are contaminated by Fe, Mn and Al from the surrounding soil where the bones have been residing for more than 500 years, other trace elements are intact within the bones. It is shown that the elemental ratios Sr/Ca and Ba/Ca can be used as indicators of provenance. CONCLUSIONS The differences in trace element concentrations can be interpreted as indications of varying diet and provenance as a function of time in the life of the individual - a concept which can be termed chemical life history. A few examples of the results of such analyses are shown, which contains information about provenance and diagenesis.

Toxicological interactions of silver nanoparticles and non-essential metals in human hepatocarcinoma cell line

Toxicological interaction represents a challenge to toxicology, particularly for novel contaminants. There are no data whether silver nanoparticles (AgNPs), present in a wide variety of products, can interact and modulate the toxicity of ubiquitous contaminants, such as nonessential metals. In the current study, we investigated the toxicological interactions of AgNP (size=1-2nm; zeta potential=-23mV), cadmium and mercury in human hepatoma HepG2 cells. The results indicated that the co-exposures led to toxicological interactions, with AgNP+Cd being more toxic than AgNP+Hg. Early (2-4h) increases of ROS (DCF assay) and mitochondrial O2- levels (Mitosox® assay) were observed in the cells co-exposed to AgNP+Cd/Hg, in comparison to control and individual contaminants, but the effect was partially reverted in AgNP+Hg at the end of 24h-exposure. In addition, decreases of mitochondrial metabolism (MTT), cell viability (neutral red uptake assay), cell proliferation (crystal violet assay) and ABC-transporters activity (rhodamine accumulation assay) were also more pronounced in the co-exposure groups. Foremost, co-exposure to AgNP and metals potentiated cell death (mainly by necrosis) and Hg2+ (but not Cd2+) intracellular levels (ICP-MS). Therefore, toxicological interactions seem to increase the toxicity of AgNP, cadmium and mercury.

Pre-Columbian treponemal infection in Denmark?- a paleopathological and archaeometric approach

The aim of this paper is to investigate five new cases of possible treponematosis in early medieval Denmark. A total of 1018 skeletons from Danish and present day German cemeteries have been examined, and five candidates of pre-Columbian individuals have been selected from three Danish burial sites on Funen, Jutland and Zealand. The five individuals with a possible infection with treponematoses have been analysed anthropological and chemically.Two of the skeletons exhibited cranial lesions, i.e. serpiginous and focal superficial cavitation. The other three only displayed periosteal reactions of varying degrees on the postcranial skeleton. Computed tomography scans showed focal obliteration of the periosteum on the long bones as well as on the affected skulls. Radiocarbon dates and stable isotope analyses indicate that three of the four analysed skeletons predate AD 1493. High levels of mercury in three of the individuals suggest that medical treatment with Hg-containing medicine took place.Considering the climate and geography at the sites, venereal syphilis might be the treponemal disease causing the pathologies on the skeletal remains. However, the historical background, the bone lesions and their prevalence point to the presence of a less aggressive, maybe non-venereal, form of treponematosis. Consequently, the hypothesis that pre-Columbian venereal syphilis existed among the analysed skeletal material is rejected with the help of various archaeometric analyses.

Ammonia chemistry within Danish churches.

The increase of agricultural intensity over the last century in rural Denmark has meant that ammonia has been regarded as a significant environmental problem. The deterioration of murals in rural churches is also a matter of concern and focused attention on the potential for ammonia to accelerate damage. Ammonia concentrations measured over 12 months inside and outside nine churches often show a spring maximum outdoors, hinting at the importance of farming activities. The ammonia concentrations are on average some three times greater indoors than outdoors and mass balance calculations suggest that this arises from the decomposition of ammonium nitrate aerosols. The emissions may result from reactions of aerosols deposited at the alkaline walls, which also leads to calcium nitrate becoming the major soluble salt at the very surface layer. The quantities remain small enough, that they probably do not participate in salt damage to the murals.

Monitoring the accumulated water soluble airborne compounds deposited on surfaces of showcases and walls in museums, archives and historical buildings

BackgroundCultural heritage objects are subject to the deposition of a multitude of airborne pollutants even when kept inside museums, archives, historical buildings or showcases. Some of the pollutants are quickly deposited onto any available surface, including the interior walls and CH objects themselves. This might make the compounds seem absent from analyses of indoor air samples.Context and purpose of the studyA new method of detecting water soluble pollutants without taking samples from the interior walls or from the CH objects themselves has been developed. The method involves sampling the pollutants accumulated on a surface near the CH object, e.g. a nearby wall or an interior glass surface of a showcase. The samples were obtained by gently flushing the surface with deionised water to collect the ions readily removed from the surface. The method was tested on a variety of surfaces.Results and main findingsThe flushed water were analysed with IC (Ion Chromatography) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) and included ions of Al, As, Ba, Ca, CH3COOH, Cl, Co, (COOH)2, Cr, Cu, F, Fe, K, Mg, Mn, Na, NH4, Ni, Pb, S, Sb, Si, Sn, Sr, Ti and Zn, and the ions NO3−, PO43−, and SO42−. The resulting concentrations were converted to µEq, providing the ionic balance and the relative amounts of the ions and elements present. Ionic balance was observed on smooth and inert surfaces, but in some cases the chemistry of the wall contributed to the flush water. Solid samples of some of the surfaces have been analysed by XRF to clarify these more complex situations.ConclusionsClear results appear from smooth or well defined surfaces, whereas more complex situations arise when the underlying surface itself contributes to the flush water. The method is working very well and is easy and cheap to implement by curators and conservators, who can the send the flush water to specialized laboratories.Brief summaryA new methodology capable of monitoring the accumulated airborne deposits on surfaces in showcases and historic buildings is presented and tested. The method is cheap and is easy to implement by curators and conservators and allows the assessment of threats to the CH objects which are not always observed by analyses of the indoor air. Graphical abstractA novel method is presented detecting water soluble airborne pollutants without taking samples of the cultural heritage objects themselves. Left: schematic diagram depicting the sampling method. a Handheld squeeze bottle; b funnel made from aluminum foil to collect the flushed water; c plastic bottle collecting the flushed water; right: applying the flush water on the interior glass wall of a show case (Photo: Kaare Lund Rasmussen)

Mercury in soil surrounding medieval human skeletons

Studying medieval skeletons is a direct way to obtain information about life in medieval societies with very little other information available about the living conditions of ordinary people. In this paper we investigate how Hg is distributed in soil samples surrounding seven medieval skeletons excavated at the cemeteries Lindegaarden in Ribe and Ole Wormsgade in Horsens, both situated in Jutland, Denmark.The analyses have been performed using Cold Vapour Atomic Absorption Spectroscopy (CV-AAS). The results show systematic variations of the Hg concentrations in soil samples as a function of distance extending horizontally from the femur. Two individuals showed soil Hg concentrations at the background level, below ca. 100 ng g-1, whereas soil samples surrounding the other five individuals exhibited much larger Hg concentrations.Our interpretation of the data is that in general the Hg, which was once situated in the soft tissue, is still present and in-place in the soil now surrounding the skeleton. Due to the overburden of ca. 3 feet of topsoil the residual of the soft tissue has been condensed into the mid-plane of the flattened corpse. The decomposed soft tissue now mixed with the soil can in this way be sampled near the femur as well as from the inner organs: the kidneys, the liver and the lungs.