Getting from here to there – energy technology transformation pathways in the EMF27 scenarios

Based on a large number of energy-economic and integrated assessment models, the Energy Modeling Forum (EMF) 27 study systematically explores the implications of technology cost and availability for feasibility and macroeconomic costs of energy system transformations toward climate stabilization. At the highest level, the technology strategy articulated in all the scenarios in EMF27 includes three elements: decarbonization of energy supply, increasing the use of low-carbon energy carriers in end-use, and reduction of energy use. The way that the scenarios differ is in the degree to which these different elements of strategy are implemented, the timing of those implementations, and the associated macroeconomic costs. The study also discusses the value of individual technologies for achieving climate stabilization. A robust finding is that the unavailability of carbon capture and storage and limited availability of bioenergy have the largest impact on feasibility and macroeconomic costs for stabilizing atmospheric concentrations at low levels, mostly because of their combined ability to remove carbon from the atmosphere. Constraining options in the electric sector such as nuclear power, wind and solar energy in contrast has a much smaller impact on the cost of mitigation.     

Emission of aliphatic amines from animal husbandry and their reactions: Potential source of N2O and HCN

We measured the emissions of volatile aliphatic amines and ammonia produced by the manure of beef cattle, dairy cows, swine, laying hens and horses in livestock buildings. The amine emissions consisted almost exclusively of the three methylamines and correlated with those of ammonia. The molar emission ratios of the methylamines to ammonia, and data on NH₃ emissions from animal husbandry in Europe, together with global statistics on domestic animals, were used to estimate the global emissions of amines. Annual global methylamine-N input to the atmosphere from animal husbandry in 1988 was 0.15±0.06 TgN (Tg=10¹² g). Almost 3/4 of these emissions consisted of trimethylamine-N. This represents about half of all methylamine emissions to the atmosphere. Other sources are marine coastal waters and biomass burning.Possible reaction pathways for atmospheric methylamines are shown. Among various speculative but possible products N₂O and HCN are of interest because the emission of methylamines could contribute to the global budgets of these compounds. Maximum atmospheric N₂O production from methylamines are below 0.4 Tg N/year, which is less than 10% of the annual N₂O growth rate. Although we do not expect the methylamine emissions to contribute in a major way to the atmospheric N₂O budget, more studies are needed to establish this conclusion beyond doubt. Similar conclusions hold for HCN.     

Comparison of organic contaminants found in mussels and oysters from a current mussel watch project with those from archived mollusc samples of the 1970s

Organic contaminant concentrations in mussels and oysters were compared between archived samples of a Mussel Watch Program of the 1970s and samples collected more recently by the National Oceanic and Atmospheric Admnistration's National Status and Trends Program. Archived samples were analysed using current analytical techniques. Chlorinated pesticides and PAHs (polyaromatic hydrocarbons) displayed significant decreases between the 1970s and the 1990s. Polychlorinated biphenyls (PCBs) and butyltins were found in higher concentrations in 1986 than in the 1970s samples. Concentrations for both have decreased since 1986. The original 1970s analytical results were also compared with current analytical results from archived samples. Results were comparable for DDE and were generally comparable for the greater than three-ring PAHs. Results were also comparable for PCBs, even though the early methods quantified Arochlor 1254 and the more recent method quantifies PCBs by congener.     

Grand canyon—a quantitative approach to the erosion and weathering of a stratified bedrock

A new method is proposed for solving a differential equation arising from weathering-limited development of a valley. Allowance is made for horizontal stratification and overhang can be allowed to develop. The model is applied to the Grand Canyon and comments are included on its relevance.     

Hydrothermal alteration and tectonic evolution of an intermediate- to fast-spreading back-arc oceanic crust: Late Ordovician Solund-Stavfjord ophiolite, western Norway

Abstract The Solund‐Stavfjord ophiolite complex (SSOC) in western Norway represents a remnant of the Late Ordovician oceanic lithosphere, which developed in an intermediate‐ to fast‐spreading Caledonian back‐arc basin. The internal architecture and magmatic features of its crustal component suggest that the SSOC has a complex, multistage sea floor spreading history in a supra‐subduction zone environment. The youngest crustal section associated with the propagating rift tectonics consists of a relatively complete ophiolite pseudostratigraphy, including basaltic volcanic rocks, a transition zone between the sheeted dyke complex and the extrusive sequence, sheeted dykes, and high‐level isotropic gabbros. Large‐scale variations in major and trace element distributions indicate significant remobilization far beyond that which would result from magmatic processes, as a result of the hydrothermal alteration of crustal rocks. Whereas K₂O is strongly enriched in volcanic rocks of the extrusive sequence, Cu and Zn show the largest enrichment in the dyke complex near the dyke–volcanic transition zone or within this transition zone. The δ¹⁸O values of the whole‐rock samples show a general depletion structurally downwards in the ophiolite, with the largest and smallest variations observed in volcanic rocks and the transition zone, respectively. δ¹⁸O values of epidote–quartz mineral pairs indicate 260–290°C for volcanic rocks, 420°C for the transition zone, 280–345°C for the sheeted dyke complex and 290–475°C for the gabbros. The ⁸⁷Sr/⁸⁶Sr isotope ratios show the widest range and highest values in the extrusive rocks (0.70316–0.70495), and generally the lowest values and the narrowest range in the sheeted dyke complex (0.70338–0.70377). The minimum water/rock ratios calculated show the largest variations in volcanic rocks and gabbros (approximately 0–14), and generally the lowest values and range in the sheeted dyke complex (approximately 1–3). The δD values of epidote (?1 to ?12‰), together with the δ¹⁸O calculated for Ordovician seawater, are similar to those of present‐day seawater. Volcanic rocks experienced both cold and warm water circulation, resulting in the observed K₂O‐enrichment and the largest scatter in the δ¹⁸O values. As a result of metal leaching in the hot reaction zone above a magma chamber, Zn is strongly depleted in the gabbros but enriched in the sheeted dyke complex because of precipitation from upwelling of discharged hydrothermal fluids. The present study demonstrates that the near intact effect of ocean floor hydrothermal activity is preserved in the upper part of the SSOC crust, despite the influence of regional lower greenschist facies metamorphism.     

Origin and dynamics of groundwater salinity in the alluvial plains of western Delhi and adjacent territories of Haryana State,India

Groundwater salinity is a widespread problem and a challenge to water resources management. It is an increasing concern in the alluvial plains of Delhi and neighbouring Haryana state as well as a risk for agricultural production water supply and sustainable development. This study aims to identify potential sources of dissolved salts and the driving mechanisms of salinity ingress in the shallow aquifer. It combines a comprehensive review of environmental conditions and the analysis of groundwater samples from 25 sampling points. Major ions are analysed to describe the composition and distribution of saline groundwater and dissolution/precipitation dynamics. Density stratification and local upconing of saline waters were identified by multilevel monitoring and temperature logging. Bromide–chloride ratios hold information on the formation of saline waters, and nitrate is used as an indicator for anthropogenic influences. In addition, stable isotope analysis helps to identify evaporation and to better understand recharge processes and mixing dynamics in the study region. The results lead to the conclusion that surface water and groundwater influx into the poorly drained semiarid basin naturally results in the accumulation of salts in soil, sediments and groundwater. Human‐induced changes of environmental conditions, especially the implementation of traditional canal and modern groundwater irrigation, have augmented evapotranspiration and led to waterlogging in large areas. In addition, water‐level fluctuations and perturbation of the natural hydraulic equilibrium favour the mobilisation of salts from salt stores in the unsaturated zone and deeper aquifer sections. The holistic approach of this study demonstrates the importance of various salinity mechanisms and provides new insights into the interference of natural and anthropogenic influences. Copyright © 2011 John Wiley & Sons, Ltd.     

Groundwater – the disregarded component in lake water and nutrient budgets. Part 2: effects of groundwater on nutrients

Lacustrine groundwater discharge (LGD) transports nutrients from a catchment to a lake, which may fuel eutrophication, one of the major threats to our fresh waters. Unfortunately, LGD has often been disregarded in lake nutrient studies. Most measurement techniques are based on separate determinations of volume and nutrient concentration of LGD: Loads are calculated by multiplying seepage volumes by concentrations of exfiltrating water. Typically low phosphorus (P) concentrations of pristine groundwater often are increased due to anthropogenic sources such as fertilizer, manure or sewage. Mineralization of naturally present organic matter might also increase groundwater P. Reducing redox conditions favour P transport through the aquifer to the reactive aquifer‐lake interface. In some cases, large decreases of P concentrations may occur at the interface, for example, due to increased oxygen availability, while in other cases, there is nearly no decrease in P. The high reactivity of the interface complicates quantification of groundwater‐borne P loads to the lake, making difficult clear differentiation of internal and external P loads to surface water. Anthropogenic sources of nitrogen (N) in groundwater are similar to those of phosphate. However, the environmental fate of N differs fundamentally from P because N occurs in several different redox states, each with different mobility. While nitrate behaves essentially conservatively in most oxic aquifers, ammonium's mobility is similar to that of phosphate. Nitrate may be transformed to gaseous N₂ in reducing conditions and permanently removed from the system. Biogeochemical turnover of N is common at the reactive aquifer‐lake interface. Nutrient loads from LGD were compiled from the literature. Groundwater‐borne P loads vary from 0.74 to 2900 mg PO₄‐P m^?2 year^?1; for N, these loads vary from 0.001 to 640 g m^?2 year^?1. Even small amounts of seepage can carry large nutrient loads due to often high nutrient concentrations in groundwater. Large spatial heterogeneity, uncertain areal extent of the interface and difficult accessibility make every determination of LGD a challenge. However, determinations of LGD are essential to effective lake management. Copyright © 2014 John Wiley & Sons, Ltd.