A preliminary assessment of nitrous oxide in Chalk groundwater in Cambridgeshire, U.K.

Groundwater samples from boreholes and springs in the unconfined Chalk aquifer of Cambridgeshire were analysed for N₂O and other N species on a monthly basis between March 1995 and February 1996. Land use in the study area is devoted to intensive arable farming supported by the application of N-based fertilisers. All groundwater samples were strongly oversaturated with N₂O, with concentrations ranging from 13 to 320 times the saturation concentration with respect to air-equilibrated water.A very good positive correlation between N₂O and NO₃ concentrations was obtained (r²=0.80), but no relationship was established between N₂O and NO₂ or NH₄ concentrations. Concentrations of N₂O and NO₃ increased continuously in the direction of groundwater flow, with molar net gain ratios of NO₃ to N₂O varying between 204 and 410. These ratios are within the range reported in previous studies of nitrification. Corresponding dissolved O₂ levels in groundwater samples were moderately undersaturated, further indicating that the main source of N₂O in Chalk groundwater in Cambridgeshire is probably nitrification. No consumption of N₂O seems to take place within the unconfined aquifer with degassing to the atmosphere apparently being the sole mechanism for N₂O removal from groundwater.An estimated N₂O flux of around 0.05 kg N₂O ha⁻¹ a⁻¹ from the sampled groundwater discharge points to the atmosphere was calculated for the study area. This figure is likely to be much higher, since it does not account for diffuse N₂O emissions from groundwater seepage areas or any degassing from the unconfined aquifer through the unsaturated zone. Both these processes will contribute substantially to the total aerial flux, thus suggesting that groundwater may be a significant contributor to the global N₂O budget.     

Possibilities of oil shale mining under the Selisoo mire of the Estonia oil shale deposit

The paper presents results of the study on oil shale mining (Estonia underground mine) possibilities under the Selisoo mire. The Selisoo area is 2,051 ha in extent, and most of the mire is in natural state. Peat layer consists of thick (4.4–6.5 m) oligotrophic peat. Mining under Selisoo will go at depths 65–70 m under the surface. The mining field of the Estonia mine was planned between Ahtme and Viivikonna fault zones. The lowest hydraulic conductivity of carbonate rocks 0.11 l/day per m² is found in the Oandu layer and for peat it is 0.35–0.0002 m/day. Therefore, together they form a good aquitard. When the annual rainfall amount is the highest, the difference between horizontal water inflow and runoff is positive with 127,000 m³. Positive water balance is guaranteed in case of precipitation being at least 540 mm/year. The positive water balance is important for preserving the ecological system of Selisoo mire. For guaranteeing long-term stability of mine pillars, a new calculation method has been elaborated, based on the conventional calculation scheme, where the factor of safety is more than 2.3. Rheological processes are out of question, collapse of the pillars is impossible. Stability of the underground constructions and overburden rocks must be “eternal”. The criteria were elaborated for oil shale mining and will guarantee preservation of mires in natural or close to natural state.     

Matrix-independent Fe isotope ratio determination in silicates using UV femtosecond laser ablation

UV femtosecond laser ablation coupled to MC-ICP-MS provides a promising in situ tool to investigate elemental and isotope ratios by non-matrix-matched calibration. In this study, we investigate Fe isotope composition in siliceous matrices including biotite, hornblende, garnet, fayalite and forsterite (San Carlos Olivine), and an oceanic Fe–Mn crust using the iron reference material IRMM-014 for calibration. To test the accuracy of the laser ablation data, Fe isotope compositions were obtained independently by solution ICP-MS after chromatographic separation of Fe. Sample materials with low Cr content, i.e. biotite, hornblende, fayalite and the Fe–Mn crust, reveal δ^56/54Fe and δ^57/54Fe values that agree with those from solution ICP-MS data within the measured precision. For high Cr concentration (⁵⁴Cr/⁵⁴Fe >0.0001), i.e. in the garnet and forsterite sample, δ^56/54Fe and δ^57/54Fe values were derived from ⁵⁷Fe/⁵⁶Fe ratios as correction of the isobaric interference of ⁵⁴Cr on ⁵⁴Fe is unsatisfactory. This approach provides accurate results for both minerals. Moreover, the garnet crystal exhibits isotopic zonation with differences of 0.3‰ in δ^56/54Fe showing that substantial heterogeneities exist in high-temperature metamorphic minerals. Multiple analyses of homogeneous sample materials reveal a repeatability of 0.1‰ (2 SD) for δ^56/54Fe and 0.2‰ (2 SD) for δ^57/54Fe, respectively. This study adds to the observations of Horn et al. (2006) who have shown that the determination of Fe isotope ratios in various matrices including iron alloys, iron oxides and hydroxides, iron sulfide and iron carbonates can be performed with high accuracy and precision at high spatial resolution using UV femtosecond laser ablation ICP-MS. These results demonstrate that femtosecond laser ablation ICP-MS is a largely matrix-independent method, which provides a substantial advantage over commonly employed nanosecond laser ablation systems.     

Knowledge absorption of optical technology companies in Shanghai, Pudong: Successes, barriers and structural impediments

Knowledge absorption theories argue that technologically less advanced companies (latecomer firms) can substantially upgrade their knowledge base through active knowledge absorption. These theories view knowledge absorption as a stepwise process which includes a linkage phase, a leverage phase and a learning phase (LLL concept). Case studies in Taiwan and Korea have shown that latecomer firms can indeed follow this approach and catch-up technologically with advanced firms. This paper aims to discuss the relevance of the LLL concept in China using the example of Optical Technology (OT). It reveals that the concept is not universally applicable. In the case of China, the ownership of companies determines successes and failures of strategies for increasing knowledge absorption. Private firms face substantial difficulties in establishing the necessary linkages; the upgrading of foreign-invested enterprises (FIEs) is controlled by their parent companies. This result has implications for theoretical concepts of learning and innovation in China, as well as for policy.     

Micro-scale tracing of Fe and Si isotope signatures in banded iron formation using femtosecond laser ablation

We have detected micrometre-scale differences in Fe and Si stable isotope ratios between coexisting minerals and between layers of banded iron formation (BIF) using an UV femtosecond laser ablation system connected to a MC-ICP-MS. In the magnetite–carbonate–chert BIF from the Archean Old Wanderer Formation in the Shurugwi Greenstone Belt (Zimbabwe), magnetite shows neither intra- nor inter-layer trends giving overall uniform δ⁵⁶Fe values of 0.9‰, but exhibits intra-crystal zonation. Bulk iron carbonates are also relatively uniform at near-zero values, however, their individual δ⁵⁶Fe value is highly composition-dependent: both siderite and ankerite and mixtures between both are present, and δ⁵⁶Fe end member values are 0.4‰ for siderite and −0.7‰ for ankerite. The data suggest either an early diagenetic origin of magnetite and iron carbonates by the reaction of organic matter with ferric oxyhydroxides catalysed by Fe(III)-reducing bacteria; or more likely an abiotic reaction of organic carbon and Fe(III) during low-grade metamorphism. Si isotope composition of the Old Wanderer BIF also shows significant variations with δ³⁰Si values that range between −1.0‰ and −2.6‰ for bulk layers. These isotope compositions suggest rapid precipitation of the silicate phases from hydrothermal-rich waters. Interestingly, Fe and Si isotope compositions of bulk layers are covariant and are interpreted as largely primary signatures. Moreover, the changes of Fe and Si isotope signatures between bulk layers directly reflect the upwelling dynamics of hydrothermal-rich water which govern the rates of Fe and Si precipitation and therefore also the development of layering. During periods of low hydrothermal activity, precipitation of only small amounts of ferric oxyhydroxide was followed by complete reduction with organic carbon during diagenesis resulting in carbonate–chert layers. During periods of intensive hydrothermal activity, precipitation rates of ferric oxyhydroxide were high, and subsequent diagenesis triggered only partial reduction, forming magnetite–carbonate–chert layers. We are confident that our micro-analytical technique is able to detect both the solute flux history into the sedimentary BIF precursor, and the BIF’s diagenetic history from the comparison between coexisting minerals and their predicted fractionation factors.     

Cosmogenic effects on Li/Li, B/B, and W/W in CAIs from carbonaceous chondrites

This study focuses on cosmogenic effects on lithium, boron, and tungsten isotopes in CAIs from carbonaceous chondrites. The results for lithium isotopes have been used to properly correct experimental data obtained by Chaussidon et al. (2006a) for Allende CAI 3529-41 for cosmogenic contributions. After proper correction, the new inferred ratios slightly but systematically differ from the original ones, indicating that the original study slightly overestimated the cosmogenic corrections. A statistical interpretation of the data indicates that there is a non-linear correlation between ⁷Li/⁶Li and ⁹Be/⁶Li that might be interpreted as a disturbed isochron. For boron isotopes, the data obtained here confirm that cosmogenic corrections on the ¹⁰Be-¹⁰B dating system are indeed very minor and can in most cases be neglected. However, a statistical interpretation of the data demonstrates that the type of the fitting procedure used can significantly change the results. It is demonstrated that a fitting procedure using the uncertainties as weights gives a slope about 50% shallower compared to the slope obtained using a non-weighted fitting procedure (for the same data). Such a difference can be wrongly interpreted as an age difference of about one half-life. The modeled results for tungsten isotopes clearly demonstrate that cosmic-ray effects might be of importance for samples having high Ta/W ratios due to thermal neutron capture on ¹⁸¹Ta to form ¹⁸²W. This effect does not increase the scatter of the data around the isochron but increases the slope of the isochron and therefore gives too old formation ages for the studied CAIs. Consequently, a proper handling of cosmic-ray induced shifts is necessary for high precision ¹⁸²Hf-¹⁸²W dating studies.     

Network configurations and R&D activities of the ICT industry in Suzhou municipality, China

This paper analyzes the network structure and R&D activities of the information and communication technology (ICT) industry in Suzhou municipality, known previously for its local state-directed Sunan model of development. Suzhou, however, has been undergoing dramatic restructuring to remake itself into a globalizing production center. We highlight the significance of the Chinese state and local/regional assets in shaping the trajectories of globalization and regional development, and the increasing importance of domestic markets and regional clusters/agglomeration for foreign ventures. We have found that Suzhou’s development path, heavily dependent on external forces, has made Suzhou a TNC (transnational corporation) satellite district. We also find that the ICT industry in Suzhou has a dual-structure, segmented between foreign-invested enterprises (FIEs) and domestic firms. TNCs tend to network among themselves and their interfirm networks are increasingly domestic and regionally embedded in the Yangtze River Delta, while the linkages between TNCs and local firms are weak. We argue that there is a series of technological, structural, spatial, and institutional “mismatches” that limits the establishment of “global pipelines” of knowledge exchange. We hold that the nature of global-local networks is contingent upon regional endogenous capacities and the specific ways in which global capital interacts with local institutions. Therefore, perspectives on TNCs’ local embeddedness must be positioned in their regional/external networks. We also analyze the constraints placed on Suzhou’s development into an innovative city and promote the integration of global and local/regional assets through development of indigenous capacities.