Complexation of aqueous elements by DOC in a clay aquitard

The extent of partitioning of several elements (Cu, Mn, Mo, Ni, Sr, U, and Zn) on dissolved organic carbon (DOC) was investigated in pore water samples collected from a clay-rich aquitard. High DOC concentrations in the aquitard, ranging from 21 to 143 mg C/L, and natural aqueous metal concentrations higher than in most ground water environments facilitated complexation studies at this site. Analyses were conducted using on-line coupling of asymmetrical flow field-flow fractionation with ultraviolet, total organic carbon, and inductively coupled plasma-mass spectrometry detectors. Of the elements investigated, only U and Zn were complexed with all DOC samples, ranging from 2.2 to 60 microg U/g DOC (0.4% to 3% of the total U in the pore water) and 0.04 to 0.5 microg Zn/g DOC (0.1% to 0.9% of the total Zn in the pore water), respectively. Laboratory experiments conducted over a range in pH (1.3 to 9.7) and geochemical modeling supported the measured complexation of U and Zn on the DOC. The in situ association constant, K(d), for U decreased with depth from 76 mL/g C for pore water samples at 2.2 m below ground (BG) to 24 mL/g C at 9.7 m BG. The decrease was attributed to a decrease in aromaticity of the DOC with depth. Zn K(d)constants ranged from 2 to 12 mL/g C and exhibited no trend with depth. Results of the current study suggest minor masses of U and Zn (less than or equal to 4% of total) complex with this DOC under in situ pH conditions. Our data suggest that competitive complexation by other ligands may limit the importance of DOC-facilitated transport of the elements studied in water of similar chemical composition.     

Late local glacial maximum in the Central Altiplano triggered by cold and locally-wet conditions during the paleolake Tauca episode (17–15 ka,Heinrich 1)

The timing and causes of the last deglaciation in the southern tropical Andes is poorly known. In the Central Altiplano, recent studies have focused on whether this tropical highland was deglaciated before, synchronously or after the global last glacial maximum (～21 ka BP). In this study we present a new chronology based on cosmogenic ³He (³He_c) dating of moraines on Cerro Tunupa, a volcano that is located in the centre of the now vanished Lake Tauca (19.9°S, 67.6°W). These new ³He_c ages suggest that the Tunupa glaciers remained close to their maximum extent until 15 ka BP, synchronous with the Lake Tauca highstand (17–15 ka BP). Glacial retreat and the demise of Lake Tauca seem to have occurred rapidly and synchronously, within dating uncertainties, at ～15 ka BP. We took advantage of the synchronism of these events to combine a glacier model with a lake model in order to reconstruct precipitation and temperature during the Lake Tauca highstand. This new approach indicates that, during the Tauca highstand (17–15 ka BP), the centre of the Altiplano was characterized by temperature ～6.5 °C cooler and average precipitation higher by a factor ranging between ×1.6 and ×3 compared to the present. Cold and wet conditions thus persisted in a significant part of the southern tropical Andes during the Heinrich 1 event (17–15 ka BP). This study also demonstrates the extent to which the snowline of glaciers can be affected by local climatic conditions and emphasizes that efforts to draw global climate inferences from glacial extents must also consider local moisture conditions.     

Climate policies after Fukushima: three views

The 2011 Japanese earthquake and tsunami, and the consequent accident at the Fukushima nuclear power plant, have had consequences far beyond Japan itself. Reactions to the accident in three major economies Japan, the UK, and Germany, all of whom were committed to relatively ambitious climate change targets prior to the accident are examined. In Japan and Germany, the accident precipitated a major change of policy direction. In the UK, debate has been muted and there has been essentially no change in energy or climate change policies. The status of the energy and climate change policies in each country prior to the accident is assessed, the responses to the accident are described, and the possible impacts on their positions in the international climate negotiations are analysed. Finally, the three countries' responses are compared and some differences between them observed. Some reasons for their different policy responses are suggested and some themes, common across all countries, are identified

Policy relevance

The attraction of nuclear power has rested on the promise of low-cost electricity, low-carbon energy supply, and enhanced energy independence. The Fukushima accident, which followed the Japanese tsunami of March 2011, has prompted a critical re-appraisal of nuclear power. The responses to Fukushima are assessed for the UK, Germany, and Japan. Before the accident, all three countries considered nuclear as playing a significant part in climate mitigation strategies. Although the UK Government has continued to support nuclear new build following a prompt review of safety arrangements, Japan and Germany have decided to phase out nuclear power, albeit according to different timescales. The factors that explain the different decisions are examined, including patterns of energy demand and supply, the wider political context, institutional arrangements, and public attitudes to risk. The implications for the international climate negotiations are also assessed.     

Impacts on agriculture following the 1991 eruption of Vulcan Hudson, Patagonia: lessons for recovery

Large explosive eruptions have the potential to distribute heavy ashfalls across large areas, resulting in physical and chemical impacts on agriculture, and economic and psycho-social impacts on rural communities. This study investigates how affected agriculture and rural communities have adapted, absorbed and mitigated impacts following a range of ashfall thicknesses (>2 m?C<1 mm) from the 12?C15 August 1991 eruption of Vulcan Hudson, one of the largest eruptions of the twentieth century. An estimated 1 million livestock died after the eruption due to pasture burial by ashfall and ongoing suppression of vegetation recovery. Horticulturalists suffered ongoing damage to crops from wind-blown ash and changes to soil properties increased irrigation and cultivation requirements. Real or perceived impacts on human health and impacts on farm productivity from the ashfall resulted in evacuation of farms and small towns in the short term. Long-term farm abandonment occurred in areas of heavy ashfall (upper Ibáñez valley) and highly stressed farming systems, even where ashfall was relatively thin (<50 mm), such as the Argentine steppe. The mono-agricultural system of sheep farming in the steppe region had few options other than destocking, proving less resilient than the diverse high-intensity horticultural and pastoral mix in irrigated valleys, which allowed more rapid adaption through diversification of production. Farms with natural advantages and greater investment in capital improvements led to greater damage potential initially (at least in cost terms), but ultimately provided a greater capacity for response and recovery. Better soils, climate and significantly greater access to technological improvements such as cultivation tools, irrigation and wind breaks were advantageous, such as at Chile Chico (Chile), Los Antiguos and Perito Moreno (Argentina). Cultivation increased chemical and physical soil fertility, especially when used in combination with fertilisation and irrigation. Appropriate use of seeds and cropping techniques within the new soil and growing conditions was important. Government agencies had a vital role in the dissemination of information for appropriate farm management responses, ash chemistry analysis, evacuations and welfare, and in the longer term to provide technical and credit assistance to facilitate recovery.     

Trophic ecology of the sea urchin Spatangus purpureus elucidated from gonad fatty acids composition analysis

Irregular sea urchins such as the spatangoid Spatangus purpureus are important bioturbators that contribute to natural biogenic disturbance and the functioning of biogeochemical cycles in soft sediments. In the coastal waters of the Balearic Islands S. purpureus occurs in soft red algal beds, and can reach high densities. The diet of S. purpureus is unknown and it is particularly difficult to analyze the stomach contents of this group; therefore, we analyzed the fatty acid (FA) composition of the gonads and potential food resources in order to assess the trophic relationships of this species. The FA profiles of the gonads of S. purpureus agree well with the FA composition of the potential trophic resources (algae and sediment) and reveals changes between localities with different available resources. Three polyunsaturated FAs mainly contributes in the composition in the S. purpureus gonads: eicosapentaenoic acid (C20:5n-3) and arachidonic acid (C20:4n-6), both abundant in the macroalgal material, and palmitoleic acid (C16:1n-7), which is characteristic of sediment samples. Trophic markers of bacterial input and carnivorous feeding were significantly more abundant in sea urchins caught on bottoms with less vegetation. The current study demonstrates that the FA content of S. purpureus gonads is a useful marker of diet, as differences in the profiles reflected the variations in detritus composition. The results of this study show that this species has omnivorous feeding behavior; however, viewed in conjunction with available abundance data the results suggest that phytodetritus found within algal beds is an important carbon source for this species.     

Variation of the low-degree solar acoustic mode parameters over the solar cycle

VIRGO/SPM is a helioseismic sunphotometer on board SOHO that observes the disk-integrated sunlight irradiance at three different colors (red, green, and blue). The data obtained for SPM since the beginning of the SOHO mission, April 1996, to March 2001 have been used to study the differences of the p-mode parameters during the solar activity cycle. These time series have been divided in sub-series of 100 days, transformed to power spectra and averaged in sets of three to yield a total number of six averaged power spectra (around one per year). A new way of analyzing the power spectrum has been applied to the six power spectra of each color; it consists of fitting the whole p-mode spectrum at once with a unique background. The results for the frequencies, line widths, power, mode energy, energy rate fed in the mode and splittings along the activity cycle are found, compared and discussed.     

Lead miners' soughs in Derbyshire

Long before the science of geology was established, the Derbyshire lead miners used elementary practical geology in laying out the lines of their soughs, or drainage levels, to gain any possible advantage of easier excavation. Their objective was to lower the water table, so as to make the deeper parts of mineral veins available for exploitation.