Animal fats are preserved at archaeological sites in association with unglazed pottery, human and animal remains, and other deposits or hoards. High-temperature gas chromatography (HT-GC) and combined HT-GC/mass spectrometry (HT-GC/MS) has confirmed the presence of animal fats in lipid extracts of artifacts. Degradation products and pathways have been discerned through the analyses of archaeological finds and the products of laboratory and field-based decay experiments. The origins of preserved fats have been determined through detailed compositional analysis of their component fatty acids by GC, by GC/MS of dimethyl disulfide derivatives of monoenoic components, and by GC-combustion-isotope ratio-MS (GC-C-IRMS), to derive diagenetically robust delta(13)C values. Regiospecific analysis of intact triacylglycerols by high-performance liquid chromatography/MS (HPLC/MS), with atmospheric pressure chemical ionization, provides a further criterion for establishing the origin of fats. Preparative GC has been employed to isolate individual fatty acids from archaeological pottery in sufficient amounts for (14)C dating.

Estuarine sediments are the location for significant bacterial removal of anthropogenically derived inorganic nitrogen, in particular nitrate, from the aquatic environment. In this study, rates of benthic denitrification (DN), dissimilatory nitrate reduction to ammonium (DNRA), and anammox (AN) at three sites along a nitrate concentration gradient in the Colne estuary, United Kingdom, were determined, and the numbers of functional genes (narG, napA, nirS, and nrfA) and corresponding transcripts encoding enzymes mediating nitrate reduction were determined by reverse transcription-quantitative PCR. In situ rates of DN and DNRA decreased toward the estuary mouth, with the findings from slurry experiments suggesting that the potential for DNRA increased while the DN potential decreased as nitrate concentrations declined. AN was detected only at the estuary head, accounting for ϳ30% of N 2 formation, with 16S rRNA genes from anammox-related bacteria also detected only at this site. Numbers of narG genes declined along the estuary, while napA gene numbers were stable, suggesting that NAP-mediated nitrate reduction remained important at low nitrate concentrations. nirS gene numbers (as indicators of DN) also decreased along the estuary, whereas nrfA (an indicator for DNRA) was detected only at the two uppermost sites. Similarly, nitrate and nitrite reductase gene transcripts were detected only at the top two sites. A regression analysis of log(n ؉ 1) process rate data and log(n ؉ 1) mean gene abundances showed significant relationships between DN and nirS and between DNRA and nrfA. Although these log-log relationships indicate an underlying relationship between the genetic potential for nitrate reduction and the corresponding process activity, fine-scale environmentally induced changes in rates of nitrate reduction are likely to be controlled at cellular and protein levels.Estuaries are major conduits for the transport of anthropogenically derived nitrogen (e.g., from fertilizer runoff and from wastewater treatment plants) from land to sea (18,20). Estuarine sediments are now recognized as being an important location for the removal of inorganic nitrogen from this environment via benthic nitrate reduction to nitrogenous gases (21). Previously, we have utilized the isotope-pairing technique (22) to investigate rates of denitrification (DN) of nitrate to N 2 O and N 2 along the nitrate and salinity gradients in the hypernutrified Colne estuary, United Kingdom, and demonstrated that DN rates are highest at the estuary head, where nitrate levels are also at their highest (7, 9). However, DN represents only one of three key pathways relevant to nitrate reduction, with a recent review suggesting that the importance of DN in aquatic systems may be overstated (3). A substantial proportion of nitrate may alternatively be converted to ammonium (1, 16, 17) via dissimilatory nitrate reduction to ammonium (DNRA), in which case inorganic nitrogen is retained within the aquatic environment. Nitrite, usually derived from nitrate reduc...

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