Methods of soil P analysis in archaeology

Phosphorus (P) is unique among the elements in being a sensitive and persistent indicator of human activity. It has long been of interest to archaeologists because of its potential to inform them about the presence of past human occupation and to offer clues regarding the type and intensity of human activity. A wide variety of methods have been developed in both soil science and in archaeology to extract and measure soil P, resulting in a tremendous amount of data and a wide array of interpretations, but also considerable confusion over appropriateness of methods and terminology. The primary purpose of this paper is to address these issues by clarifying soil P analyses. Anthropogenic additions of phosphorus to the soil come from human refuse and waste, burials, the products of animal husbandry in barns, pens, and on livestock paths, or intentional enrichment from soil fertilizer. Once added to the soil, phosphorus in its common form as phosphate is stable and generally immobile in soils. Soil P comes in many forms, organized for the purposes of this paper on the basis of extraction and measurement procedures as (1) extraction for available P (Pav); (2) portable field techniques (the spot test or ring test); (3) chemical digestion of a soil sample for total P (Ptot); (4) extractions of inorganic P (Pin) for fractionation studies and extractions to look at individual compounds of P; (5) measurements of organic P (Porg); and (6) extractions for total elemental analysis. To compare the suitability of various extractants as the “best” indicator of human input and activity we subjected samples from three very different archaeological sites (Lubbock Lake, TX; Hulburt Creek, IA; British Camp, WA) to four methods of soil P extraction: perchloric acid digestion (Ptot), sulfuric–nitric acid extraction Ptot), hydrochloric acid extraction after ignition (Pin), and citric acid extraction (Pav). Further, methods of measurement were compared via colorimetry vs. Inductively Coupled Plasma (ICP) spectrometry, and the two methods of supposed “total P” were both measured via ICP. In general, the stronger extractants yielded more soil P, but the result are not clear-cut. Likely variables include the intensity of occupation, nature of the parent material, and postdepositional weathering (e.g., the addition of dust).     

Small things in perspective: the contribution of our blind tests to micro-residue studies on archaeological stone tools

Our blind tests are distinctive for they were conducted on replicated stone tools used for a variety of tasks that included the processing of animal remains and plants. The analyst was required to differentiate an array of residues from microscopic morphological characteristics, using light microscopy. The original aim of our first tests was to assess the analyst's ability to identify a variety of plant and animal residues, but issues and problems that arose during the testing process made it clear that greater value might be gained from the lessons that we learnt about methodology and the direction for future micro-residue research. We show that problems identified during our first tests stimulated research. Amongst other things, we learnt to distinguish plant and animal remains more confidently than previously. Our residue analyses are firmly embedded in wider archaeological research and our tests help to explain why there are sometimes contradictions between the evidence from archaeologically recovered remains and residues on stone tools. A further outcome of the tests is that we have adopted a multi-stranded approach that provides a cautious, but secure strategy for identifying and interpreting use-residues. Our studies of contaminants through replications have also been invaluable for distinguishing incidental residues from use-related residues.     

Iron Age Landscapes of the Benue River Valley,Cameroon

The Iron Age settlements of northern Cameroon were dispersed across the landscape, taking advantage of different eco-climatic zones to exploit a variety of natural resources. Situated at the interface of the upper and lower terraces of the Benue River, mound sites in the area around Garoua have occupation histories spanning multiple centuries. The site of Langui-Tchéboua displays evidence for rapid accumulation of sediments approximately 700 years ago, which may have been a deliberate construction strategy that would have allowed the site’s inhabitants to exploit resources in both floodplain and dryland contexts. The combined use of multiple dating methods and micromorphology provide novel insights into both the mechanisms of anthropogenic landscape change and possible motivations governing those choices.     

Recovering social and cultural dynamics from plaster floors: chemical analyses at ancient Chunchucmil,Yucatan, Mexico

Phosphate analysis and trace metals analysis were used to determine activities that took place on plaster floors in domestic contexts at the ancient Maya site of Chunchucmil, Yucatan. Research on activities and the use of space contributes to an understanding of social relations within household groups as well as unforeseen patterns that structure refuse discard. The floors analyzed in this paper pertain to three structures in two neighboring houselots dating to the Early Classic (300–600 A.D.) period. Data from the chemical analyses were utilized in conjunction with associated architectural features and artifacts found on the floors. These three lines of information were interpreted with the help of models developed from ethnographic and ethnoarchaeological research. The results demonstrated functional differentiation of rooms within elaborate residences and suggested that front rooms were used to host visitors. The results also suggested that different types of debris were managed differently. Finally, chemical analyses suggest that non-elite Maya occasionally enacted rituals often restricted to elites.     

Identifying activity areas in archaeological soils from a colonial Virginia house lot using phytolith analysis and soil chemistry

Environmental archaeology methods can uncover both house lot organization and economic adaptation practices when applied systematically in conjunction with traditional archaeological research. This is the first study to employ both phytolith analysis and soil chemistry to interpret activity areas on an archaeological site. The patterning in the phytolith and soil chemistry analyses from the site of Rich Neck Plantation, Williamsburg, Virginia, reveals a set of six activity areas in and around the 17th century house lot, demonstrating a degree of economic diversification generally attributed only to 18th century colonial economic and social transformations.     

出土青铜酒器残留物分析的尝试

利用快速溶剂萃取法,从出土青铜酒器内的土壤中提取有机残留物．对其作高效液相色谱定性分析,发现其中含有酒石酸,表明这些青铜酒器在下葬时可能盛着酒。快速溶剂萃取法的萃取剂为1％磷酸（体积比）溶液,较之传统有机溶剂,操作时更为方便和安全。此方法可推广于陶器中残留物的分析．具有较为广泛的应用前景。     

Degradation processes in colourless Roman glass: cases from the Bocholtz burial

A group of Roman glass objects from the Bocholtz burial in the SW of Limburg (The Netherlands) was found to have been subject to varying degrees of degradation. Many of the 25 colourless glass objects were fragmented to pieces <0.1 cm (“sugared”), whereas the three transparent blue-green glass objects were in near-pristine state. Analyses using SEM, XRF and EDS revealed that the fragmentation was the direct result of the intense leaching of Na₂O from the glass structure and its replacement with water. The resulting gel layers with low-Na₂O contents and large amounts of water are sensitive to cracking when they dry out. Thin-walled glass appears to be less sensitive to cracking from the resulting stress than thick-walled glass. Local differences in the moisture regime during burial also influence the severity of the glass degradation. Glass with low concentrations of CaO seems to be the most sensitive to this form of degradation. The typical blue-green Roman glass is less sensitive as it generally has considerably higher concentrations of CaO.     

Ethnoarchaeological analysis of Arctic fish processing: chemical characterization of soils on Nelson Island,Alaska

Activity area analysis of archaeological soils using multi-element characterizations can illuminate how subsistence operations are organized and how subsistence behavior has changed over time, and is increasingly common at archaeological sites. However, in many regions it is impossible to examine the elemental signatures in known anthropogenic soil samples in order to compare them with unknown archaeological samples. This ethnoarchaeological study examines the chemical composition of the soils at known fish processing areas in the contemporary community of Tununak on Nelson Island, western Alaska. Using a quadrupole inductively coupled plasma mass spectrometer (Q-ICP-MS), the concentrations of the following elements in the soil extract were recorded in parts per million (ppm): aluminum (Al), barium (Ba), calcium (Ca), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), sodium (Na), phosphorus (P), strontium (Sr), titanium (Ti), and zinc (Zn). Fish processing area features are elevated in various elements, including sodium, magnesium, phosphorus, potassium, and manganese, and Ba/Sr, Ba/Ca, and Sr/Ca are also useful in distinguishing between fish processing areas and offsite areas.     

An interdisciplinary approach to the understanding of past settlement and farming: two cases from SE Norway

An interdisciplinary approach involving analysis of plant macrofossils, pollen and soil micro morphology in combination with large-scale stripping of top soil, was applied in order to get a comprehensive understanding of pre-historic settlement, farming economy and land-use in Østfold, SE Norway. Investigations of 25 sites lead to two distinctive results: 1) A time-space perspective on usages of plants, and 2) Identification of agrarian activities in a relict field. Studies of these topics have hitherto been limited for this region. The results add fresh and essential knowledge to pre-historic times in Østfold and make a significant contribution to the understanding to these topics in neighbouring regions.     

Effects of site lithology on geochemical signatures of human occupation in archaeological house plans in the Netherlands

This study presents the application of multi-element soil analyses (X-ray fluorescence spectroscopy and inductively coupled plasma optical emission spectroscopy of 1 M HCl extracts) to grid samples from 3 archaeological house plans embedded in sandy clays, clays and sands to assess effects of site lithology on geochemical signatures of human occupation.