Nitrogen cycling in western India as revealed by nitrogen isotopes,and the historic production of saltpetre

Saltpetre (KNO₃) manufacture was a principal monopoly industry in early Modern India when the United Kingdom governed the social and economic systems. The process represented microbial transformation of excrementitious livestock and human wastes deposited around habitats, resulting in formation of salt efflorescence at an economic scale. Low caste people collected these wastes for extraction and production of rough saltpetre under the administrative control of British India. Stable isotope composition (δ¹⁵N and δ¹⁸O) was used to trace details of the microbial transformation processes, often involving the isotopic fractionation of nitrogen and oxygen. Marked elevation in δ¹⁵N and δ¹⁸O values for nitrates in soils and deposits, relative to those of primary organic nitrogen in diets and water sources, characterizes the unique processes of historic saltpetre manufacture in British India.     

Towards a comprehensive strategic partnership between Australia and Japan: Japan's perspective

With 2006 and 2007 marking two important anniversaries in the history of their bilateral ties, Australia and Japan are committed to reaffirming the significance of their relationship and expanding it into new dimensions. The Australian and Japanese foreign ministers have agreed to build a ‘comprehensive strategic partnership’ between their two countries. What are the factors that motivate Canberra and Tokyo to elevate their bilateral relations to the level of a strategic partnership? From a Japanese point of view, the main reason is the enhanced strategic importance of Australia with such indicators as Australian's enhanced security role, the structural changes in Asia and movements toward a new regional architecture, Japan's energy and food security, the trilateral strategic dialogue between Australia, the United States and Japan, and shared values and the Australian government's policy toward Japan. Both nations are expected to advance toward an even closer relationship with these factors in mind.1 1. The views expressed in this article, which was written in September 2006, are those of the author and do not in any way represent the views of the Embassy of Japan in Australia or the Japanese government. View all notes     

Anthropogenic saltpetre: dual (oxygen and nitrogen) isotopic constraints to the biogeochemical processes

Saltpetre constitutes one of the major ingredients of gunpowder, which was a driving force during the political changes in late medieval to early modern times in Japan. Two types of model saltpetre mineralization are studied. One represents efflorescent saltpetre formed as the byproduct of indigo dye manufacture, whereas the second is anthropogenic, derived from relict nitre‐beds. Here, oxygen and nitrogen isotopic analysis, as expressed by δ¹⁸O and δ¹⁵N notations, is applied. The calculated δ¹⁸O values for ambient water, responsible for the microbial‐mediated oxidation of ammonium into oxygen in nitrates, tended to have higher ranges than average local meteoric waters of the relevant regions. An overall trend could be seen, showing the apparent positive nitrogen isotopic fractionation during the microbial transformation from initial organic nitrogen into nitrate product. Dual isotopic analysis for industrial nitrates provides a useful tool for investigation of the provenance of historic gunpowder. Present anthropogenic saltpetre involves positive control over temperature–moisture regimes and oxygen fugacity during formation, the process being distinctive from those prevailed in British India and other European countries.     

Salt weathering of sandstone at the Angkor monuments,Cambodia: identification of the origins of salts using sulfur and strontium isotopes

The Angkor monuments in northwestern Cambodia, which are primarily made of sandstone, are suffering from deterioration due to salt weathering. In order to elucidate the sources of the salts and salt weathering process, this paper analyzed bulk chemical compositions and S (sulfur) and Sr (strontium) isotopic ratios for the salts and surrounding environmental materials. At places where bats inhabit the structures, various kinds of sulfate and phosphate salts are formed on the surface of the sandstone. The results of the analysis demonstrate that the S and P (phosphorus) components in the salts are primarily derived from bat guano. Moreover, Ca (calcium), which is the major element in the salts, is suggested to be derived from both bat guano and the sandstone. The isotopic data strongly suggests that bat guano is related to salt weathering. Removal of these animal excrements is essential for future conservation of these monuments. On the other hand, exfoliation of sandstone commonly occurs due to crystallization of calcite (CaCO₃) on platform surfaces of pyramid-type monuments. A large amount of Ca in calcite is suggested to be derived from calcite cement of the building sandstone.