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At least 685 records · Page 38

Decomposing the Impact of Alternative Technology Sets on Future Carbon Emissions Growth

What are the drivers of future global carbon dioxide (CO2) emissions growth and how would the availability of key energy supply technologies change their relative importance? In this paper, we apply a novel index number decomposition technique to the results of a multi-region, multi-sector computable general equilibrium model to quantify the influence of five factors on the growth of future carbon emissions: (1) growth in global economic activity; (2) shifts in the regional composition of gross world product; (3) shifts in the sectoral composition of regions’ GDP; (4) changes in sectors’ energy–output ratios; and (5) changes in the CO2 intensity of energy sources. We elucidate how the relative importance of these factors changes in response to the imposition of a global carbon tax and alternative assumptions about the future availability of key energy supply technologies. Rising global economic activity and shifts in regional composition put upward pressure on emissions while changes in energy and emission intensity and the sectoral output mix have attenuating effects. A global emission tax that increases over time slows economic expansion and shifts the fuel mix, with the most pronounced impacts on China, India, and Russia. Limited availability of carbon capture and storage, nuclear, and hydroelectric generation all lead to upward shifts in the long-run marginal abatement cost curve, causing some countries to choose to pay the tax rather than abate.

Fisher-Vanden, Karen↗

Health co-benefits and mitigation costs as per the Paris Agreement under different technological pathways for energy supply

This study assesses the reductions in air pollution emissions and subsequent beneficial health effects from different global mitigation pathways consistent with the 2 °C stabilization objective of the Paris Agreement. We use an integrated modelling framework, demonstrating the need for models with an appropriate level of technology detail for an accurate co-benefit assessment. The framework combines an integrated assessment model (GCAM) with an air quality model (TM5-FASST) to obtain estimates of premature mortality and then assesses their economic cost. The results show that significant co-benefits can be found for a range of technological options, such as introducing a limitation on bioenergy, carbon capture and storage (CCS) or nuclear power. Cumulative premature mortality may be reduced by 17–23% by 2020–2050 compared to the baseline, depending on the scenarios. However, the ratio of health co-benefits to mitigation costs varies substantially, ranging from 1.45 when a bioenergy limitation is set to 2.19 when all technologies are available. As for regional disaggregation, some regions, such as India and China, obtain far greater co-benefits than others.

54 ENVIRONMENTAL SCIENCES↗

Seasonal variations and sources of atmospheric polycyclic aromatic hydrocarbons and organochlorine compounds in a high-altitude city: Evidence from four-year observations

Lijiang is a high-altitude city located on the eastern fringe of the Tibetan Plateau, with complex seasonal atmospheric circulations (i.e. westerly wind, Indian Monsoon, and East Asia Monsoon). Very few previous studies have focused on seasonal variations and sources of organic pollutants in Lijiang. In this study, a four-year air campaign from June 2009 to July 2013 was conducted to investigate the temporal trends and the sources of polycyclic aromatic hydrocarbons (PAHs) and organochlorine compounds [including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs)]. The atmospheric PAH concentrations in winter are 2-3 times of those in summer, probably because of the combined result of enhanced local emission and long-range atmospheric transport (LRAT) during winter. Traffic pollution was the primary local source of PAHs, while biomass burning is the dominant LRAT source. Different from PAHs, OCPs and PCBs mainly underwent LRAT to reach Lijiang. The peak concentrations of most of OCPs occurred in pre-monsoon season and winter, which are carried by air masses from Myanmar and India through westerly winds. As compared with other sites of the Tibetan Plateau, without the direct barrier of the Himalaya, Lijiang is easily contaminated by the incursion of polluted air masses.

Gong, Ping↗

Arsenic, lead, mercury and cadmium: Toxicity, levels in breast milk and the risks for breastfed infants

Metals are ubiquitous in nature, being found in all environmental compartments, and have a variety of applications in human activities. Metals are transferred by maternal blood to the fetus via the placenta, and exposure continues throughout life. For the general population, exposure comes mainly from water and food consumption, including breast milk. In this paper, we reviewed studies on the toxicity of arsenic, lead, mercury and cadmium, the toxic metals of most concern to human health, focusing on the potential risks to newborns and infants. A total of 75 studies published since 2000 reporting the levels of these metals in breast milk were reviewed. Lead was the metal most investigated in breast milk (43 studies), and for which the highest levels were reported (up to 1515 µg/L). Arsenic was the least investigated (18 studies), with higher levels reported for breast milk (up to 149 µg/L) collected in regions with high arsenic concentrations in water (>10 µg/L). Data from 34 studies on mercury showed that levels in breast milk were generally higher in populations with high fish consumption, where it may be present mainly as MeHg. Cadmium levels in breast milk were the lowest, with means <2 µg/L in most of the 29 studies reviewed. Results of risk assessments indicated that the intake of arsenic, lead and mercury by infants through breastfeeding can be considered a health concern in most regions of the world. Although the potential risks to infants are mostly outweighed by the benefits of breast milk consumption, it is essential that contaminants be continuously monitored, especially in the most critical regions, and that measures be implemented by health authorities to reduce exposure of newborns and infants to these metals, and thus avoid unnecessary health risks. - Highlights: • Review of 75 studies that analyzed arsenic, lead, mercury and/or cadmium levels. • Higher levels of arsenic found in India; of mercury found in Brazil. • Lead was the most detected in the studies; cadmium levels were the lowest. • Risk for breastfed babies cannot be excluded for arsenic, lead and mercury. • Risks are unavoidable, and outweighed by the benefits of breastfeeding.

54 ENVIRONMENTAL SCIENCES↗

Urinary levels of triclosan and triclocarban in several Asian countries, Greece and the USA: Association with oxidative stress

Highlights: • Triclosan and triclocarban were analyzed in 430 urine samples collected from 9 countries. • Triclosan concentrations as high as 1600 ng/mL were found in urine. • Age and gender related differences in triclosan levels were minimal. • TCC levels were marginally correlated with the oxidative stress marker, 8OHdG. Triclosan (TCS) and Triclocarban (TCC) are widely used as antimicrobial preservatives in personal care products (PCPs). Because of their potential for endocrine disrupting effects, human exposure to these chemicals is a concern. Biomonitoring studies of human exposure to TCS and TCC have shown widespread exposure of populations in western European countries and the USA. However, exposure to TCC and TCS by populations in Asian countries is less well known. In this study, concentrations of TCS and TCC were determined in human urine collected from seven Asian countries (China, India, Korea, Kuwait, Japan, Saudi Arabia, and Vietnam), and Greece and the USA. A total of 430 urine samples were analyzed for TCS and TCC, of which 355 (83%) and 82 (19%), respectively, contained measurable levels of these chemicals. The overall geometric mean [GM] concentrations of TCS and TCC, were 1.36 and 0.03 ng/mL, respectively. The highest mean concentration of TCS was found in urine from China (100 ng/mL) and the lowest concentration was found in urine from Vietnam (2.34 ng/mL). We also analyzed urinary 8-OHdG, a marker of oxidative stress, to elucidate the association with TCS and TCC levels for samples from Saudi Arabia (n=130) and a positive correlation between Ln-transformed TCC levels and 8-OHdG was found, although this was not statistically significant. This is the first study to report urinary levels of TCS and TCC in several Asian countries, especially for Vietnam, Kuwait, and Japan.

54 ENVIRONMENTAL SCIENCES↗

Response of Indian summer monsoon rainfall to remote carbonaceous aerosols at short time scales: Teleconnections and feedbacks

The effect of atmospheric aerosols on Indian monsoon is one of the scientifically challenging and societally relevant research issues of the recent decades. Past studies have derived inferences mostly based on local emissions and their impacts thereupon. However, more recent studies have shown that the remote effects driven by aerosols elsewhere could also impact the monsoon system on different time scales. Our study using an atmospheric general circulation model (AGCM) shows that regional carbonaceous aerosol emissions (from North America, Europe and North Africa and Asia) can significantly alter Indian summer monsoon rainfall. It is interesting to note that the effects of remote aerosols are larger and bear a resemblance to each other in comparison to local emissions. Here, our study reveals that the modulation of large-scale circulation induced by regional warming by carbonaceous aerosols leads to teleconnection patterns around the globe, thereby changing the precipitation depending on the phase of these disturbances. We also find that the effects of remote carbonaceous aerosols are strengthened by modulation/feedback through natural dust aerosols over the Arabian Sea with subsequent increase in rainfall over India. The results signify that the changes in the aerosol emissions in one region could lead to the change in precipitation over other regions through global teleconnection and associated feedbacks induced by regional atmospheric warming and/or cooling.

Carbonaceous aerosols↗

Probing Cretaceous-Paleogene crustal thickness in southern Tibet using quartz-zircon chronobarometry

Knowledge of the crustal thickness history of southern Tibet during the India-Asia collision is key to understanding what deformation mechanisms accommodated northward propagating crustal shortening. Thermoisotopic models suggest that a relatively thin margin of southern Asia persisted from ca. 200 to 45 Ma whereas trace element paleodepth proxies are interpreted to indicate a thinning phase from ca. 100 to 65 Ma when the crust reached ∼30 km-thickness. As neither of these methods directly measures crustal thickness, resolution of this conflict awaits development of a method that can. Here, in this study, we place bounds on the thickening history of southern Tibet using coupled quartz-zircon thermobarometry and U-Pb geochronology of granitoid plutons in the Gangdese batholith. We find that crustal thicknesses were as high (or higher) as 60–75 km at 65 Ma, or 10–15 Ma prior to the onset of hard continental collision. Magmatic inflation in the lower crust likely contributed to crustal thickening and thermal weakening of the lower crust, suggesting that pure shear in the lower crust was likely the primary accommodation mechanism for N-S shortening during collision. These data are in partial agreement with results of thermoisotopic models of crustal thickness but contradict thickness histories derived from empirical trace element proxies.

Chronobarometry↗

The international implications of national and local coordination on building energy codes: Case studies in six cities

Building energy efficiency is an important strategy for reducing greenhouse gas emissions globally. In fact, 55 countries have included building energy efficiency in their Nationally Determined Contributions (NDCs) under the Paris Agreement. This research uses building energy code implementation in six cities across different continents as case studies to assess what it may take for countries to implement the ambitions of their energy efficiency goals. Specifically, we look at the cases of Bogota, Colombia; Da Nang, Vietnam; Eskisehir, Turkey; Mexico City, Mexico; Rajkot, India; and Tshwane, South Africa, all of which are “deep dive” cities under the Sustainable Energy for All's Building Efficiency Accelerator. The research focuses on understanding the baseline with existing gaps in implementation and coordination. The methodology used a combination of surveys on code status and interviews with stakeholders at the local and national level, as well as review of published documents. We looked at code development, implementation, and evaluation. The cities are all working to improve implementation, however, the challenges they currently face include gaps in resources, capacity, tools, and institutions to check for compliance. Better coordination between national and local governments could help improve implementation, but that coordination is not yet well established. For example, all six of the cities reported that there was little to no involvement of local stakeholders in development of the national code; only one city reported that it had access to national funding to support code implementation. More robust coordination could better link cities with capacity building and funding for compliance, and ensure that the code reflects local priorities. By understanding gaps in implementation, it can also help in designing more targeted interventions to scale up energy savings.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

The Elements of Life, Photosynthesis and Genomics

I am a Professor of Biochemistry, Biophysics and Structural Biology and Plant and Microbial Biology at the University of California in Berkeley. I was born and raised in India, emigrated to the United States to attend university, earning a B.S. in Molecular Biology and a Ph.D. in Biochemistry at the University of Wisconsin in Madison. Following post-doctoral studies with Lawrence Bogorad at Harvard University where I became interested in genetic control of trace element quotas, I joined the department of Chemistry and Biochemistry at UCLA. One of the first to appreciate essential trace metals as potential regulators of gene expression, I articulated the details of the nutritional Cu regulon in Chlamydomonas. In parallel, I used genetic approaches to discover the genes governing missing steps in tetrapyrrole metabolism, including the attachment of heme to apocytochromes in the thylakoid lumen and the factors catalyzing the formation of ring V in chlorophyll. After biochemistry and classical genetics, I embraced genomics, taking a leadership role on the Joint Genome Institute’s efforts on the Chlamydomonas genome and more recently, contributing to high quality assemblies of several genomes in the green algal radiation, and large transcriptomic and proteomic datasets — focusing on the diel metabolic cycle in synchronized cultures and acclimation to key environmental and nutritional stressors — that are well-used and appreciated by the community. Finally, a new venture in Berkeley is the promotion of Auxenochlorella protothecoides as the true “green yeast” and as a platform for engineering algae to produce useful bioproducts.

59 BASIC BIOLOGICAL SCIENCES↗

Recent Progress of R&D Activities on Reduced Activation Ferritic/Martensitic Steels

Several types of reduced activation ferritic/martensitic (RAFM) steel have been developed over the past 30 years in China, Europe, India, Japan, Russia and the USA for application in ITER TBM and future fusion DEMO and power reactors. The progress has been particularly important during the past few years with evaluation of mechanical porperties of these steels before and after irradiation and in contact with different cooling media. This paper presents recent RAFM steel results obtained in ITER partner countries in relation with different TBM and DEMO options

Huang, Q.↗

Editorial for Multiscale & Multifield Coupling in Geomechanics

We are delighted to serve as guest editors for this special issue in the Journal of Rock Mechanics and Geotechnical Engineering. The purpose of this special issue is dedicated to gathering the latest research work on Multiscale & Multifield Coupling in Geomechanics, where we delve into the intricate interplay of various fields and scales that govern the behavior of geomaterials. In total, 30 manuscripts from USA, China, UK, Germany, Canada, India and United Arab Emirates are selected to be included in this issue.

58 GEOSCIENCES↗

Preface

The 25 April 2015 Gorkha, Nepal earthquake of magnitude 7.8 devastated parts of Nepal and northern India with a death toll of more than 8000. Here, several aftershocks of moderate size were recorded, including one of M7.2 on 12 May 2015 on the eastern periphery of the main rupture.

Purnachandra Rao, N.↗

In situ dehydration behavior of zeolite-like pentagonite: A single-crystal X-ray study

The structural modifications upon heating of pentagonite, Ca(VO)(Si{sub 4}O{sub 10}){center_dot}4H{sub 2}O (space group Ccm2{sub 1}, a=10.3708(2), b=14.0643(2), c=8.97810(10) A, V=1309.53(3) A{sup 3}) were investigated by in situ temperature dependent single-crystal X-ray structure refinements. Diffraction data of a sample from Poona district (India) have been measured in steps of 25 up to 250 Degree-Sign C and in steps of 50 Degree-Sign C between 250 and 400 Degree-Sign C. Pentagonite has a porous framework structure made up by layers of silicate tetrahedra connected by V{sup 4+}O{sub 5} square pyramids. Ca and H{sub 2}O molecules are extraframework occupants. Room temperature diffraction data allowed refinement of H positions. The hydrogen-bond system links the extraframework occupants to the silicate layers and also interconnects the H{sub 2}O molecules located inside the channels. Ca is seven-fold coordinated forming four bonds to O of the tetrahedral framework and three bonds to extraframework H{sub 2}O. The H{sub 2}O molecule at O9 showing a high displacement parameter is not bonded to Ca. The dehydration in pentagonite proceeds in three steps. At 100 Degree-Sign C the H{sub 2}O molecule at O8 was released while O9 moved towards Ca. As a consequence the displacement parameter of H{sub 2}O at O9 halved compared to that at room temperature. The unit-cell volume decreased to 1287.33(3) A{sup 3} leading to a formula with 3H{sub 2}O per formula unit (pfu). Ca remained seven-fold coordinated. At 175 Degree-Sign C Ca(VO)(Si{sub 4}O{sub 10}){center_dot}3H{sub 2}O transformed into a new phase with 1H{sub 2}O molecule pfu characterized by doubling of the c axis and the monoclinic space group Pn. Severe bending of specific T--O--T angles led to contraction of the porous three-dimensional framework. In addition, H{sub 2}O at O9 was expelled while H{sub 2}O at O7 approached a position in the center of the channel. The normalized volume decreased to 1069.44(9) A{sup 3}. The Ca coordination reduced from seven- to six-fold. At 225 Degree-Sign C a new anhydrous phase with space group Pna2{sub 1} but without doubling of c had formed. Release of H{sub 2}O at O7 caused additional contraction of T--O--T angles and volume reduction (V=1036.31(9) A{sup 3}). Ca adopted five-fold coordination. During heating excursion up to 400 Degree-Sign C this anhydrous phase remained preserved. Between room temperature and 225 Degree-Sign C the unit-cell volume decreased by 21% due to dehydration. The dehydration steps compare well with the thermo-gravimetric data reported in the literature. - Graphical abstract: Pentagonite structure at room temperature and at 225 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer We investigate the relationship between the removal of H{sub 2}O molecules and structural modifications of the framework of pentagonite. Black-Right-Pointing-Pointer Pentagonite undergoes phase transitions upon heating. Black-Right-Pointing-Pointer We analyze similarities and differences between pentagonite and related structures.

36 MATERIALS SCIENCE↗

Numerical simulations of sand migration during gas production in hydrate-bearing sands interbedded with thin mud layers at site NGHP-02-16

The geomechanical behavior of gas hydrate-bearing sands during gas production is complex, involving changes in hydrate-dependent mechanical characteristics and also redistribution of stresses carried by the hydrate. When an interbedded mud layer is present, the complex response of the hydrate-bearing sediments is more pronounced because hydrate dissociation tends to occur preferentially in the sands adjacent to the hydrate-free mud layer, which can act as a heat source. This leads to non-uniform sediment deformation and potentially to shearing deformation along the sand/mud layers. In addition, since the hydrate-bearing sand permeability becomes far greater than the mud permeability with hydrate dissociation, a greater hydraulic gradient may exist along the interface between the sand/mud layers. These two behaviors may contribute to sand migration and thus a thorough study on the effect of a thin interbedded mud layer on the extent of sand migration is necessary. This paper presents numerical sand migration modeling of sand/mud interbedded hydrate-bearing sediments found at Site NGHP-02-16, one of 25 sites drilled as a part of National Gas Hydrate Program Expedition 02 (NGHP-02) in the offshore of India, subjected to depressurization. For a comparison and better understanding, simulation of homogeneous hydrate-bearing sediments is also conducted. It is found that greater sand migration occurs when the interbedded mud layer is present because of greater shearing deformation and greater pressure gradients at sand-mud interface.

58 GEOSCIENCES↗