Influence of diet on the distribution of nitrogen isotopes in animals

The influence of diet on the distribution of nitrogen isotopes in animals was investigated by analyzing animals grown in the laboratory on diets of constant nitrogen isotopic composition.The isotopic composition of the nitrogen in an animal reflects the nitrogen isotopic composition of its diet. The δ₁₅N values of the whole bodies of animals are usually more positive than those of their diets. Different individuals of a species raised on the same diet can have significantly different δ¹⁵N values. The variability of the relationship between the δ¹⁵N values of animals and their diets is greater for different species raised on the same diet than for the same species raised on different diets. Different tissues of mice are also enriched in ¹⁵N relative to the diet, with the difference between the δ¹⁵N values of a tissue and the diet depending on both the kind of tissue and the diet involved. The δ¹⁵N values ofcollagen and chitin. biochemical components that are often preserved in fossil animal remains, are also related to the δ¹⁵N value of the diet.The dependence of the δ¹⁵N values of whole animals and their tissues and biochemical components on the δ¹⁵N value of diet indicates that the isotopic composition of animal nitrogen can be used to obtain information about an animal's diet if its potential food sources had different δ¹⁵N values. The nitrogen isotopic method of dietary analysis probably can be used to estimate the relative use of legumes vs non-legumes or of aquatic vs terrestrial organisms as food sources for extant and fossil animals. However, the method probably will not be applicable in those modern ecosystems in which the use of chemical fertilizers has influenced the distribution of nitrogen isotopes in food sources.The isotopic method of dietary analysis was used to reconstruct changes in the diet of the human population that occupied the Tehuacan Valley of Mexico over a 7000 yr span. Variations in the δ¹⁵C and δ¹⁵N values of bone collagen suggest that C₄ and/or CAM plants (presumably mostly corn) and legumes (presumably mostly beans) were introduced into the diet much earlier than suggested by conventional archaeological analysis.     

Oxygen and silicon isotope ratios of the Luna 20 soil

The δ O¹⁸ and δ Si³⁰ analyses of the Luna 20 soil sample are +6.18 and +0.22, respectively, relative to the SMOW and Rose Quartz standards. However, an anomalous δ O¹⁸ value of +8.13 was obtained on one aliquot of the Luna 20 sample. Possible reasons for this apparently erroneous result are discussed.     

The investment climate for climate investment: Joint Implementation in transition countries

Transition countries are expected to become important players in the emerging market for greenhouse gas emission reductions, as they can cut emissions at a relatively low cost. However, the attractiveness of the region as a supplier of emission reductions will not only depend on its cost advantage. It will also depend on the business climate offered to carbon investors—factors like a well-functioning legal and regulatory system, economic and political stability and the capacity to process emission reduction projects efficiently. This paper looks at the carbon investment climate in the transition countries eligible for Joint Implementation (JI)—Russia, Ukraine, Croatia and the EU accession countries. It concludes that JI investors will face a clear trade-off between the scope for cheap JI on the one hand, and the quality of the business environment and JI institutions on the other. The countries with the highest potential for cheap emission reductions also tend to be the countries with the most difficult business climate and the least institutional capacity for JI. The most attractive JI locations may be median countries with a reasonable JI potential and an acceptable business climate, such as Bulgaria, Romania and the Slovak Republic.     

Provenance of long‐travelled dust determined with ultra‐trace‐element composition: a pilot study with samples from New Zealand glaciers

We report high‐precision inductively coupled plasma mass spectrometric (ICP‐MS) compositional data for 39 trace elements in a variety of dust deposits, trapped sediments and surface samples from New Zealand and Australia. Dusts collected from the surface of alpine glaciers in the Southern Alps, New Zealand, believed to have undergone long‐distance atmospheric transport from Australia, are recognizable on account of their overabundances of Pb and Cu with respect to typical upper crustal values. Long‐travelled dust from Australia therefore scavenges these and other metals (e.g. Zn, Sb and Cd) from the atmosphere during transport and deposition. Hence, due to anthropogenic pollution, long‐travelled Australian dusts can be recognized by elevated metal contents. The relative abundance of 25 other elements that are not affected by atmospheric pollution, mineral sorting (Zr and Hf) and weathering[sol ]solubility (alkali and earth alkali elements) reflects the geochemistry of the dust source sediment. As a result, we are able to establish the provenance of dust using ultra‐trace‐element chemistry at regional scale. Comparison of long‐travelled dust chemistry with potential Australian sources shows that fits of variable quality are obtained. We propose that the best fitting potential source chemistry most likely represents the major dust source area. A binary mixing model is used to demonstrate that admixture of small quantities of local dust provides an even better fitting dust chemistry for the long‐travelled dusts. Copyright © 2005 John Wiley & Sons, Ltd.     

Equilibrium and Fractional Crystallization Experiments at 0{middle dot}7 GPa; the Effect of Pressure on Phase Relations and Liquid Compositions of Tholeiitic Magmas

Two series of anhydrous experiments have been performed in anend-loaded piston cylinder apparatus on a primitive, mantle-derivedtholeiitic basalt at 0·7 GPa pressure and temperaturesin the range 1060–1270°C. The first series are equilibriumcrystallization experiments on a single basaltic bulk composition;the second series are fractionation experiments where near-perfectfractional crystallization was approached in a stepwise mannerusing 30°C temperature increments and starting compositionscorresponding to that of the previous, higher temperature glass.At 0·7 GPa liquidus temperatures are lowered and thestability of olivine and plagioclase is enhanced with respectto clinopyroxene compared with phase equilibria of the samecomposition at 1·0 GPa. The residual solid assemblagesof fractional crystallization experiments at 0·7 GPaevolve from dunites, followed by wehrlites, gabbronorites, andgabbros, to diorites and ilmenite-bearing diorites. In equilibriumcrystallization experiments at 0·7 GPa dunites are followedby plagioclase-bearing websterites and gabbronorites. In contrastto low-pressure fractionation of tholeiitic liquids (1 bar–0·5GPa), where early plagioclase saturation leads to the productionof troctolites followed by (olivine) gabbros at an early stageof differentiation, pyroxene still crystallizes before or withplagioclase at 0·7 GPa. The liquids formed by fractionalcrystallization at 0·7 GPa evolve through limited silicaincrease with rather strong iron enrichment following the typicaltholeiitic differentiation path from basalts to ferro-basalts.Silica enrichment and a decrease in absolute iron and titaniumconcentrations are observed in the last fractionation step afterilmenite starts to crystallize, resulting in the productionof an andesitic liquid. Liquids generated by equilibrium crystallizationexperiments at 0·7 GPa evolve through constant SiO₂ increaseand only limited FeO enrichment as a consequence of spinel crystallizationand closed-system behaviour. Empirical calculations of the (dry)liquid densities along the liquid lines of descent at 0·7and 1·0 GPa reveal that only differentiation at the baseof the crust (1·0 GPa) results in liquids that can ascendthrough the crust and that will ultimately form granitoid plutonicand/or dacitic to rhyodacitic sub-volcanic to volcanic complexes;at 0·7 GPa the liquid density increases with increasingdifferentiation as a result of pronounced Fe enrichment, renderingit rather unlikely that such differentiated melt will reachshallow crustal levels. KEY WORDS: tholeiitic magmas; experimental petrology; equilibrium crystallization; fractional crystallization