An Assessment of the Role of an Open Shelter in Reducing Soiling and Microbial Growth on the Archaeological Site of the Bishop’s Palace,Witney, England

Two sets of twelve Portland limestone tablets were attached to carousels outside and under the open, lightweight shelter at Bishop’s Palace (Witney, England) for 18 months to assess the influence of shelters on soiling and microbiological growth on stone. At the start, and at 6-month intervals, tablets were analysed using microscopy (optical and SEM), colour measurement (spectrophotometry), weight change measurement and salt content determination (ion chromatography). Concentrations of NO₂ and SO₂ were also monitored for a month using diffusion tubes. In addition, results were compared with those obtained by the UK National Materials Exposure Programme (NMEP) on chemical weathering rates. Differences in soiling and biological growth on sheltered and unsheltered samples, and their influence on limestone decay were established. The shelter is likely to reduce biological growth by modifying the micro-environmental conditions. However, it may also exacerbate dust deposition, which might increase decay rates in the long-term.     

The Impact of Climate Change on an Archaeological Site in the Arctic

Climate change may accelerate the degradation of archaeological sites in the Arctic and lead to a loss of important historical information. This study assesses the current preservation conditions and the processes controlling the physical and chemical stability of the Qajaa kitchen midden in western Greenland. Currently, the site is well protected by low ground temperatures, permafrost and a high water/ice content, keeping the deposits anoxic. Based on 5 years of monitoring data, degradation experiments and model simulation, our results suggest that the combined effects of permafrost thaw, thermal and hydrological erosion and oxygen exposure may lead to substantial loss of archaeological evidence before the end of the 21st century.     

Geochemistry and origin of natural gases dissolved in brines from gas fields in southwest Japan

Previous geochemical studies indicated that most natural gases dissolved in brines in Japan are of microbial origin, consisting of methane produced via carbonate reduction. However, some of those from gas fields in southwest Japan contain methane relatively enriched in ¹³C, whose origin remains to be clarified. To address this issue, chemical and isotopic analyses were performed on natural gases and brines from the gas fields in Miyazaki and Shizuoka prefectures, southwest Japan. Methane isotopic signatures (δ¹³C ≈ ?68‰ to ?34‰ VPDB; δ²H ≈ ?183‰ to ?149‰ VSMOW) suggest that these gases are of microbial (formed via carbonate reduction) or of mixed microbial and thermogenic origin. The relatively high δ²H‐CH₄ values and their relationship with the δ²H‐H₂O values argue against the possibility of their formation via acetate fermentation. The δ¹³C‐CO₂ values (≈?5‰), together with the slope of the correlation between δ²H‐CH₄ and δ¹³C‐CH₄ (Δδ²H‐CH₄/Δδ¹³C‐CH₄ ≈ 1), contradict the possibility of their formation via carbonate reduction followed by partial oxidation by methanotrophs. The ³He/⁴He ratios of the gases from Miyazaki (≈0.11–1.3 Ra) and their low correlation with δ¹³C‐CH₄ values do not support an abiogenic origin. It is inferred therefore that the high δ¹³C‐CH₄ values of natural gases dissolved in brines from gas fields in southwest Japan are indications of the contribution of thermogenic hydrocarbons, although whether abiogenic hydrocarbons contribute significantly to the gases from Shizuoka requires further investigation. This study has clarified that, for the future exploration of natural gases in southwest Japan, we should adopt the strategies for conventional thermogenic gas accumulations, such as checking the content, type and maturity of organic matter in the underlying sedimentary rocks.     

Changes in the Physico-Chemical and Microbial Nature of Wetlands from the Leaching of Chromated Copper Arsenate (CCA)-Treated Wood

Abstract

Microbial activities are responsible for reducing the harmful effects of pollutants in different burial environments. Within wetlands in particular, microorganisms play an important role in the transformation of heavy metals and metalloids via direct or indirect oxidation/reduction. In turn, these microbial transformations can lead to the detoxification of pollutant elements such as copper, chromium and arsenic that comprise CCA-treated wood.

CCA was the most commonly used wood preservative in the UK (up until its partial ban in 2004). CCA prolongs the service life of wood by making it resistant to microbiological attack. As such, it has been regularly used in the construction of platforms and boardwalks in wetlands. However, recent concerns over the impact of the chemical constituents of this treatment on both the environment and human health have prompted the introduction of legislation in order to ensure that this type of treated wood is disposed of in accordance with the relevant health and safety guidelines.

In light of this information, it is important to assess changes in the physico-chemical and microbial nature of wetlands associated with the leaching of CCA from wooden structures. The results will not only provide a greater scope for understanding the implications associated with the in situ preservation of the archaeological resource contained within these environments, but also highlight the potential ramifications for wetland ecosystem dynamics.     

微生物分子生态学技术在文物保护中应用的进展

微生物分子生态学技术近年来在文物保护研究中得到了广泛的应用,已经成为控制文物被微生物侵害的一个不可或缺的工具。本研究较系统地总结了国内外利用微生物分子生态学技术进行文物保护研究的进展,为更有效防治微生物危害侵蚀文物,进而长久的保存文物提供理论支持。