[OIII] Electron temperatures in planetary nebulae

Relative level populations for O III, derived using electron impact excitation rates calculated with the R-matrix code, are used to deduce the electron-temperature-sensitive emission-line ratioR=I(2s ²2p^{2 1}D–2s²2p21S)/I(2s² 2p23P_1,2–2s²2p^{2 1}D) =I(4363 Å)/I(4959 + 5007 Å) for a range ofTe = (7500–20000 K) applicable to planetary nebulae. Electron temperatures deduced from the observed values ofR in several planetary nebulae are in excellent agreement with those determined fromTe-sensitive line ratios in other species, including CIII]/C [II], [NII] and [ArIII], which provides support for the accuracy of the atomic data adopted in the level population calculations.     

Ar XIII line ratios in solar flares

Theoretical ArXIII electron-density-sensitive emission line ratios, derived using electron impact excitation rates interpolated from accurateR-matrix calculations, are presented forR ₁ =I(242.22 )/I(236.27 ),R ₂ =I(210.46 )/I(236.27 ), andR ₃ =I(248.68 )/I(236.27 ). Electron densities deduced from the observed values ofR ₁,R ₂, andR ₃ for solar flares obtained with the NRL S082A slitless spectrograph on boardSkylab are in excellent agreement, and furthermore compare favorably with those determined from line ratios in CaXV, which is formed at a similar electron temperature to that of ArXIII. These results provide experimental support for the accuracy of the atomic data adopted in the analysis, as well as for the techniques used to calculate the line ratios.     

Emission line ratios for Fexxi applicable to the XUV spectra of solar flares

Electron impact excitation rates for Fexxi, calculated with theR-matrix code, are used to determine theoretical electron density sensitive emission line ratios involving transitions in the 121–146 wavelength range. The observed ratios for a solar flare, obtained with a grazing spectrometer on board the OSO-5 satellite, imply electron densities which are consistent, with discrepancies that do not exceed 0.3 dex. In addition, the derived values ofN _e are similar to those estimated for the high temperature regions of other solar flares. This provides experimental support for the accuracy of the atomic data adopted in the line ratio calculations.     

Climate action for food security in South Asia? Analyzing the role of agriculture in nationally determined contributions to the Paris agreement

The Nationally Determined Contributions (NDCs) submitted under the Paris Agreement propose a country’s contribution to global mitigation efforts and domestic adaptation initiatives. This paper provides a systematic analysis of NDCs submitted by South Asian nations, in order to assess how far their commitments might deliver meaningful contributions to the global 2°C target and to sustainable broad-based adaptation benefits. Though agriculture-related emissions are prominent in emission profiles of South Asian countries, their emission reduction commitments are less likely to include agriculture, partly because of a concern over food security. We find that income-enhancing mitigation technologies that do not jeopardize food security may significantly augment the region’s mitigation potential. In the case of adaptation, analysis shows that the greatest effort will be directed towards protecting the cornerstones of the ‘green revolution’ for ensuring food security. Development of efficient and climate-resilient agricultural value chains and integrated farming bodies will be important to ensuring adaptation investment. Potentially useful models of landscape level climate resilience actions and ecosystem-based adaptation are also presented, along with estimates of the aggregate costs of agricultural adaptation. Countries in the region propose different mixes of domestic and foreign, and public and private, adaptation finance to meet the substantial gaps.

Key policy insights

• Though substantial potential for mitigation of agricultural emissions exists in South Asia, governments in the region do not commit to agricultural emissions reductions in their NDCs.

• Large-scale adoption of income-enhancing technologies is the key to realizing agricultural mitigation potential in South Asia, whilst maintaining food security.

• Increasing resilience and profitability through structural changes, value chain interventions, and landscape-level actions may provide strong options to build adaptive capacity and enhance food security.

• Both private finance (autonomous adaptation) and international financial transfers will be required to close the substantial adaptation finance gap

     

A simplified approach to analysing historical and recent tritium data in surface waters

Tritium concentrations in river and stream waters from different locations can be compared by normalizing them using the ratio of tritium concentrations in precipitation and surface water (C_p/C_s) in the study area. This study uses these ratios in a hydrological residence time context to make regional‐ and global‐scale comparisons about river basin dynamics. Prior to the advent of nuclear weapons testing, the C_p/C_s ratio was greater than or equal to 1 everywhere because of the decay of tritium in the watershed after it was deposited by precipitation. After an initial increase in the ratios during the bomb peak, the ratio dropped to less than 1 for most surface waters in the following years. This post‐bomb change in the ratio is due to the retention of the bomb‐pulse water in watersheds on timescales that are long relative to the residence time of tritium in the atmosphere. Ratios were calculated for over 6500 measurements of tritium in river and stream waters compiled by the International Atomic Energy Agency. These measurements span the post‐nuclear era (1940s to present) and include many long‐term datasets, which make it possible to examine residence times of waters in watersheds on a global basis. Plotting C_p/C_s versus time shows that ratios tended to reach a minimum in approximately one to two decades after the bomb peak for most locations. This result suggests that changes affecting quantity and quality of river flows need to be assessed on a multi‐decadal timescale. These long lag times have significant implications for assessing climate or land‐use change impacts on a large number of river systems around the world. The continuing value of tritium in studying surface water systems for both the Southern and Northern Hemisphere is also demonstrated. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

Demarcation of palaeochannels and integrated ground water resources mapping in parts of Hisar district,Haryana

Present study deals with the demarcation of palaeochannels and mapping of integrated water resources in parts of Hisar district, Haryana using Indian Remote Sensing Satellite (IRS-1D) LISS-III Data of December 21, 2001. The landforms identified are Sand Dune, Dune Complex, Aeolian Plain, Fluvioaeolian plain, Palaeochannel and Younger Alluvial Plain formed by aeolian, fluvio-aeolian, and fluvial processes. These palaeochannels are first time demarcated in the area. The ground water prospects of various geomorphic units have been assessed. Depth to water level and ground water quality maps were digitized and put in to GIS format. Ground water prospects and quality maps were integrated and depth to water level information was draped on it to prepare final integrated ground water resources map. This map depicts ground water prospects, quality and depth together in a single map, which will help in and ground water exploration.     

Simulating the impacts of climate change on cotton production in India

General circulation models (GCMs) project increases in the earth’s surface air temperatures and other climate changes by the mid or late 21st century, and therefore crops such as cotton (Gossypium spp L.) will be grown in a much different environment than today. To understand the implications of climate change on cotton production in India, cotton production to the different scenarios (A2, B2 and A1B) of future climate was simulated using the simulation model Infocrop-cotton. The GCM projections showed a nearly 3.95, 3.20 and 1.85 °C rise in mean temperature of cotton growing regions of India for the A2, B2 and A1B scenarios, respectively. Simulation results using the Infocrop-cotton model indicated that seed cotton yield declined by 477 kg?ha^?1 for the A2 scenario and by 268 kg?ha^?1 for the B2 scenario; while it was non-significant for the A1B scenario. However, it became non-significant under elevated [CO₂] levels across all the scenarios. The yield decline was higher in the northern zone over the southern zone. The impact of climate change on rainfed cotton which covers more than 60 % of the country’s total cotton production area (mostly in the central zone) and is dependent on the monsoons is likely to be minimum, possibly on account of marginal increase in rainfall levels. Results of this assessment suggest that productivity in northern India may marginally decline; while in central and southern India, productivity may either remain the same or increase. At the national level, therefore, cotton production is unlikely to change with climate change. Adaptive measures such as changes in planting time and more responsive cultivars may further boost cotton production in India.     

Application of heavy stable isotopes in forensic isotope geochemistry: A review

Light stable isotopes have been used for many years to characterize the source and transport of materials. More recently heavy isotope systems such as Sr, Nd and Pb have been added to this list in order to aid source identification. With the advent of multiple collector ICP-MS, the range of isotopic tools now available has increased considerably, however, until the isotope systematics of these new non-traditional isotope systems have become better understood, they will not be as useful in characterizing material source and transportation. Applications using heavy metal stable isotopes (mostly traditional heavy isotopes) have reached most avenues in science, including earth sciences, archaeology, anthropology, animal physiology, ecology and toxicology. This field will continue to grow as new applications are developed and techniques become simpler and quicker. This paper provides a review of how this field has grown and presents two new applications using Pb and Sr isotopes in glazes to determine the source of ore used in glazes, and using Sr isotopes to determine the origin of undocumented deceased Mexican border crossers.