A New Appraisal of Sri Lankan BB Zircon as a Reference Material for LA‐ICP‐MS U‐Pb Geochronology and Lu‐Hf Isotope Tracing

A potential zircon reference material (BB zircon) for laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) U‐Pb geochronology and Hf isotope geochemistry is described. A batch of twenty zircon megacrysts (0.5–1.5 cm³) from Sri Lanka was studied. Within‐grain rare earth element (REE) compositions are largely homogeneous, albeit with some variation seen between fractured and homogeneous domains. Excluding fractured cathodoluminescence bright domains, the variation in U content for all analysed crystals ranged from 227 to 368 μg g^?1 and the average Th/U ratios were between 0.20 and 0.47. The Hf isotope composition (0.56–0.84 g/100 g Hf) is homogeneous within and between the grains – mean ¹⁷⁶Hf/¹⁷⁷Hf of 0.281674 ± 0.000018 (2s). The calculated alpha dose of 0.59 × 10¹⁸ g^?1 for a number of BB grains falls within the trend of previously studied, untreated zircon samples from Sri Lanka. Aliquots of the same crystal (analysed by ID‐TIMS in four different laboratories) gave consistent U‐Pb ages with excellent measurement reproducibility (0.1–0.4% RSD). Interlaboratory assessment (by LA‐ICP‐MS) from individual crystals returned results that are within uncertainty equivalent to the TIMS ages. Finally, we report on within‐ and between‐grain homogeneity of the oxygen isotope systematic of four BB crystals (13.16‰ VSMOW).     

Rapakivi granites

Rapakivi granites, especially the famous rapakivis from southern Finland, are some of the most attractive building and decorative stones, used world-wide because of their striking textures and beautiful colours. But rapakivi granites are more than just building material, they have also been studied scientifically for over 100 years to try to explain the formation of their plagioclase-mantled alkali feldspar ovoids, the rapakivi feldspars which are responsible for the unique texture of the rock. Despite all the work which has been done on them, the formation of this distinctive texture is still not fully understood. Rapakivi granite complexes are not just a 'pretty face', they are also associated with important tin deposits in Rondônia and Amazonas in Brazil.     

Rhuddanian to Aeronian (Llandovery,early Silurian) carbon isotope stratigraphy throughout carbonate sequences in the upper Yangtze region,South China block

The Xiangshuyuan Formation (middle Rhuddanian to middle Aeronian stages of the Llandovery Series, lower Silurian) records a shelly fauna representing recovery after the end-Ordovician mass extinction in a well-oxygenated shallow carbonate platform of the Upper Yangtze region, South China Block. Carbon isotope stratigraphy is documented from limestone sequences of the formation at the Qiankou section, northeast Guizhou. The early Aeronian carbon isotope excursion (EACIE, with an amplitude of about 2 ‰ and peak value of 2.44 ‰) is identified in the middle and upper parts of the formation (Ozarkodina obesa conodont Biozone). The EACIE recorded herein correlates well with those in Baltica, Canada, and the United States; together with its records from organic material (δ¹³C_org) the data verify that the EACIE is a global event. The beginning of the EACIE can be used as a chemostratigraphic marker defining the Rhuddanian/Aeronian boundary in strata that lack high-resolution biostratigraphic constraints.     

U–Pb zircon chronostratigraphy of early-Pliocene ignimbrites from La Pacana, north Chile: implications for the formation of stratified magma chambers

High spatial resolution U–Pb dates of zircons from two consanguineous ignimbrites of contrasting composition, the high-silica rhyolitic Toconao and the overlying dacitic Atana ignimbrites, erupted from La Pacana caldera, north Chile, are presented in this study. Zircons from Atana and Toconao pumice clasts yield apparent ²³⁸U/²⁰⁶Pb ages of 4.11±0.20 Ma and 4.65±0.13 Ma (2σ), respectively. These data combined with previously published geochemical and stratigraphic data, reveal that the two ignimbrites were erupted from a stratified magma chamber. The Atana zircon U–Pb ages closely agree with the eruption age of Atana previously determined by K–Ar dating (4.0±0.1 Ma) and do not support long (>1 Ma) residence times. Xenocrystic zircons were found only in the Toconao bulk ignimbrite, which were probably entrained during eruption and transport. Apparent ²³⁸U/²⁰⁶Pb zircon ages of 13 Ma in these xenocrysts provide the first evidence that the onset of felsic magmatism within the Altiplano–Puna ignimbrite province occurred approximately 3 Myr earlier than previously documented.     

Optimization of the Sampling Technique for the Determination of Dissolved Hydrogen in Groundwater

In this study a field‐sampling technique for dissolved hydrogen (H₂) in groundwater will be presented which allows the transport of gaseous samples into the laboratory for further analysis. The method consists of transferring the headspace trapped in a gas‐sampling bulb which is continuously purged by groundwater into previously evacuated vials using a gas‐tight syringe. Three transfer steps with preceding evacuation of the vial led to a H₂‐recovery of 100 % in laboratory experiments. The method has been applied to determine H₂ concentrations in an aquifer contaminated with chlorinated solvents. Tests concerning the effect of different pumping techniques on H₂ concentrations revealed that most reliable values were obtained with a bladder pump, while an electrically driven submersible pump generated considerable amounts of hydrogen due to electrochemical interactions with the sampled water. Concentrations of dissolved hydrogen in field and laboratory samples were about two orders of magnitude higher when sampling was performed with the electrically driven submersible pump compared to sampling with the bladder pump and a peristaltic pump. Lab experiments with a Plexiglas reservoir to produce H₂‐enriched water were used to study the effect of two tubing materials (PVC, polyamide) on H₂ losses. PVC tubing turned out to allow transfer of H₂‐enriched water over 25 m without significant losses, while PA‐tubing was not suitable for sampling of H₂.     

Greenhouse gas emission mitigation plan for the State of Israel: strategies,incentives and reporting

In the context of the negotiations under the United Nations Framework Convention on Climate Change and its accompanying Kyoto Protocol, participating nations have recognized the need for formulating Nationally Appropriate Mitigation Actions (NAMAs). These NAMAs allow countries to take into account their national circumstances and to construct measures to mitigate GHG emissions across economic sectors. Israel has declared to the UN that it would strive to reduce its GHG emissions by 20% in the year 2020 relative to a ‘business as usual' scenario. With its growing population and an expanding economy, the national GHG mitigation plan was developed to draw a course for steering the Israeli economy into a low-carbon future while accommodating continued economic growth. The article describes relevant policy measures, designed to aid in the implementation of the plan and compares them with measures being undertaken by different countries. Emphasis is placed on analysing the progress to date, opportunities and barriers to attaining the ultimate GHG emissions reduction goals. The objective of this article is to contribute to the knowledge base of effective approaches for GHG emissions reduction. We emphasize the integrated approach of planning and implementation that could be especially useful for developing countries or countries with economies in transition, as well as for developed countries. Yet, in the article we argue that NAMAs’ success hinges on structured tracking of progress according to emerging global consensus standards such as the GHG Protocol Mitigation Goals Standard.

Policy relevance:

The study is consistent with the NAMA concept, enabling a country to adopt a ‘climate action plan’ that contributes to its sustainable development, while enabled by technology and being fiscally sound.

The analysis shows that although NAMAs have been framed in terms of projects, policies, and goals, current methodologies allow only the calculation of emission reductions that can be attributed to distinct projects. Currently, no international guidance exists for quantifying emissions reduction from policy-based NAMAs, making it difficult to track and validate progress. This gap could be addressed by an assessment framework that we have tested, as part of a World Resources Institute pilot study for an emerging voluntary global standard.     

Standardization of baseline and additionality determination under the CDM

Clean Development Mechanism (CDM) project developers have long complained about the complexities of project-specific baseline setting and the vagaries of additionality determination. In response to this, the CDM Executive Board took bold steps towards the standardization of CDM methodologies, culminating in the approval of guidelines for the establishment of performance standards in November 2011. The guidelines specify a performance standard stringency level for both baseline and additionality of 80% for several priority sectors and 90% for all other sectors. However, an analysis of 14 large-scale CDM methodologies that use performance standard approaches challenges this top-down approach to the performance standard design. An appropriate performance standard stringency level strongly depends on sector and technology characteristics. A single stringency level for baseline and additionality determination is appropriate only for greenfield projects, but not for retrofit ones. Overly simple, highly aggregated performance standards are unlikely to ensure high environmental integrity, and difficult questions regarding stringency and updating frequency will eventually have to be addressed on a rather disaggregated level. A careful balance between data requirements and the practicability of performance standards is essential because the heavy data requirements of the existing performance standard methodologies have been the key barrier to their actual implementation.

Policy relevance

CDM regulators have been pushed by many stakeholders to standardize baseline setting and eliminate project-specific additionality determination. At first glance, performance standards seem to provide the perfect solution for both tasks. However, a one-size-fits-all political decision – e.g. the average of the top 20% performers as enshrined in the Marrakech Accords – is inappropriate. Substantial disaggregation of performance standards is required both technologically and geographically in order to limit over- and under-crediting and close loopholes for non-additional projects. As a lack of reliable and complete data has been and will be a key bottleneck for the development of performance standards, international support for data collection will be indispensable, but costly, and time-consuming. Empirically driven, techno-economic assessments of performance standard stringency levels must be the central task of the future work on standardized methodologies, and should not be sidelined by perceived needs of policy makers to take bold decisions under time pressures.     

Military Emissions, Armed Conflicts, Border Changes and the Kyoto Protocol

The impacts of military activities in peacetime, military action and territorial changes on greenhouse gas emission commitments of nations under the Kyoto Protocol are analysed. We propose rules and institutional responsibilities to deal with the repercussions of such changes on markets in emission permits and national commitments aiming at prevention of serious distortions.