Governance characteristics of large marine ecosystems

The Large Marine Ecosystem (LME) concept is widely established as a large-scale approach to coastal and marine management. LME-oriented activities have focused mainly on natural sciences. Socioeconomic and governance aspects have only recently been receiving increased attention. The 64 LMEs that have been defined appeared to exhibit considerable diversity in characteristics that would be expected to affect governability. This paper explores two questions: (1) Do the LMEs vary widely enough in geopolitical complexity that different approaches to governance may be required for different LMEs? (2) Are there groups of LMEs within which one might take similar approaches to governance? The analysis demonstrates that there is considerable heterogeneity among LMEs with regard to characteristics that would be expected to affect governability. It concludes that a diversity of governance approaches will be required to cope with this heterogeneity. It also appears that LMEs can be grouped according to these characteristics. This suggests that different approaches could be considered for clusters rather than for individual LMEs and that there can be sharing of experience and learning within clusters. The types of relationships between features of LMEs and the ‘best’ approaches to marine governance are discussed in the context of emerging governance ideas.     

Modelling biofilm growth in the presence of carbon dioxide and water flow in the subsurface

The concentration of greenhouse gases – particularly carbon dioxide (CO₂) – in the atmosphere has been on the rise in the past decades. One of the methods which have been proposed to help reduce anthropogenic CO₂ emissions is the capture of CO₂from large, stationary point sources and storage in deep geological formations. The caprock is an impermeable geological layer which prevents the leakage of stored CO₂, and its integrity is of utmost importance for storage security. Due to the high pressure build-up during injection, the caprock in the vicinity of the well is particularly at risk of fracturing. Biofilms could be used as biobarriers which help prevent the leakage of CO₂ through the caprock in injection well vicinity by blocking leakage pathways. The biofilm could also protect well cement from corrosion by CO₂-rich brine.     

ANALYSIS OF COUNT DATA USING POISSON REGRESSION*

In geographical research the data of interest are often in the form of counts. Standard regression analysis is inappropriate for such data, but if certain assumptions are met, a form of regression based on the Poisson distribution can be used. This paper illustrates the use of Poisson regression in the computer package GLIM with an example from historical geography. Apprentice migration to Edinburgh is regressed on a combination of categorical, count, and continuous explanatory variables.     

Deterministic vs. probabilistic earthquake hazards and risks

Both probabilistic and deterministic methods have a role in seismic hazard and risk analyses performed for decision-making purposes. These two methods can complement one another to provide additional insights to the seismic hazard or risk problem. One method will have priority over the other, depending on how quantitative are the decisions to be made, depending on the seismic environment, and depending on the scope of the project (single site or a region). In many applications a recursive analysis, where deterministic interpretations are triggered by probabilistic results and vice versa, will give the greatest insight and allow the most informed decisions to be made.     

'On the rocks': New Zealand's coastal bach landscape and the case of Rangitoto Island

Abstract:  A distinctive feature of many of New Zealand's coastal landscapes has been the rudimentarily constructed holiday home known as a 'bach'. In recent years, however, rapidly escalating beachfront property prices, and the associated development of elite residential landscapes, have threatened the status of the bach. This commentary examines the diminishing number of 'classic' kiwi baches, and specifically considers the case of Rangitoto, a volcanic island close to central Auckland. Here, the location of baches on publicly owned land has been controversial and the small number that remains symbolize curiosities from another time and place.     

Interfacial tension measurements and wettability evaluation for geological CO2 storage

Interfacial interactions, namely interfacial tension, wettability, capillarity and interfacial mass transfer are known to govern fluid distribution and behavior in porous media. Therefore the interfacial interactions between CO₂, brine and oil and/or gas reservoirs have a significant influence on the effectiveness of any CO₂ storage operations. However, data and knowledge of interfacial properties in storage conditions are scarce. This issue becomes particularly true in the case of deep saline aquifers where limited, economically driven, data collection and archiving are available. In this paper, we present a complete set of brine–CO₂ interfacial tension data at pressure, temperature and salinity conditions, representative of a CO₂ storage operation. A semi-empirical correlation is proposed to calculate the interfacial tension from the experimental data. Wettability is studied at pore scale, using glass micromodels in order to track fluids distribution as a function of the thermodynamic properties and wettability conditions for water–CO₂ systems. With this approach, we show that, in strongly hydrophilic porous media, the CO₂ does not wet the solid surface whereas; if the porous media has less hydrophilic properties the CO₂ significantly wets the surface.     

Characterization of kerogens and study of their evolution by infrared spectroscopy: carbonyl and carboxyl groups

Measurements of the absorption coefficient of the band around 1710cm^?1, combined with adequate chemical treatments, allow an evaluation of the importance of carbonyl, carboxylic acid and ester groups in various series of kerogens. The concentration of carbonyl and acid groups, the concentration of oxygenated functions other than carbonyl or carboxyl, and the total oxygen content are higher in shallow kerogens originating from higher plants than in those containing an important algal contribution; however the concentration of ester groups varies in the opposite direction.The carboxylic acid groups are the most sensitive to catagenetic evolution or pyrolysis. The carbonyl groups are removed progressively as evolution proceeds but a fraction of them is retained up to advanced degrees of evolution.Study of the band at 1630cm^?1 has shown that, besides the bending vibration of molecular water, there is some contribution of bridged quinones and unsaturated hydrocarbons. However at least 50% of the absorption coefficient is due to polyaromatic structures. This band is generally much more intense for kerogens originating from higher plants.     

New radiometric and petrological constraints on the evolution of the Pichincha volcanic complex (Ecuador)

Fieldwork, radiometric (⁴⁰Ar/³⁹Ar and ¹⁴C) ages and whole-rock geochemistry allow a reconstruction of eruptive stages at the active, mainly dacitic, Pichincha Volcanic Complex (PVC), whose eruptions have repeatedly threatened Quito, most recently from 1999 to 2001. After the emplacement of basal lavas dated at ∼1100 to 900 ka, the eruptive activity of the old Rucu Pichincha volcano lasted from ∼850 ka to ∼150 ka before present (BP) and resulted in a 15 × 20 km-wide edifice, which comprises three main building stages: (1) A lower stratocone (Lower Rucu, ∼160 km³ in volume) developed from ∼850 to 600 ka; (2) This edifice was capped by a steeper-sided and less voluminous cone (the Upper Rucu, 40–50 km³), the history of which started 450–430 ka ago and ended around 250 ka with a sector collapse; (3) A smaller (8–10 km³) but more explosive edifice grew in the avalanche amphitheatre and ended Rucu Pichincha's history about 150 ka ago. The Guagua Pichincha volcano (GGP) was developed from 60 ka on the western flank of Rucu with four growth stages separated by major catastrophic events. (1) From ∼60 to 47 ka, a basal effusive stratocone developed, terminating with a large ash-and-pumice flow event. (2) This basal volcano was followed by a long-lasting dome building stage and related explosive episodes, the latter occurring between 28–30 and 22–23 ka. These first two stages formed the main GGP (∼30 km³), a large part of which was removed by a major collapse 11 ka BP. (3) Sustained explosive activity and viscous lava extrusions gave rise to a new edifice, Toaza (4–5 km³ in volume), which in turn collapsed around 4 ka BP. (4) The ensuing amphitheatre was partly filled by the ∼1-km³ Cristal dome, which is the historically active centre of the Pichincha complex. The average output rate for the whole PVC is 0.29 km³/ka. Nevertheless, the chronostratigraphic resolution we obtained for Lower Rucu Pichincha and for the two main edifices of Guagua Pichincha (main GGP and Toaza), leads to eruptive rates of 0.60–0.65 km³/ka during these construction stages. These output rates are compared to those of other mainly dacitic volcanoes from continental arcs. Our study also supports an overall SiO₂ and large-ion lithophile elements enrichment as the PVC develops. In particular, distinctive geochemical signatures indicate the involvement of a new magma batch at the transition between Rucu and Guagua. At the GGP, the same phenomenon occurs at each major collapse event marking the onset of the ensuing magmatic stage. Since the 11-ka-BP collapse event, this magmatic behaviour has led to increasingly explosive activity. Four explosive cycles of between 100 and 200 years long have taken place at the Cristal dome in the past 3.7 ka, and repose intervals between these cycles have tended to decrease with time. As a consequence, we suggest that the 1999–2001 eruptive period may have initiated a new eruptive cycle that might pose a future hazard to Quito (∼2 million inhabitants).     

Komatiites and nickel sulfide ores of the Black Swan area,Yilgarn Craton,Western Australia. 3: Komatiite geochemistry,and implications for ore forming processes

The Black Swan komatiite sequence is a package of dominantly olivine-rich cumulates with lesser volumes of spinifex textured rocks, interpreted as a section through an extensive komatiite lava flow field. The sequence hosts a number of nickel sulfide orebodies, including the Silver Swan massive shoot and the Cygnet and Black Swan disseminated orebodies. A large body of whole rock analyses on komatiitic rocks from the Black Swan area has been filtered for metasomatic effects. With the exception of mobile elements such as Ca and alkalis, most samples retain residual igneous geochemistry, and can be modelled predominantly by fractionation and accumulation of olivine. Whole rock MgO–FeO relationships imply a relatively restricted range of olivine compositions, more primitive than the olivine which would have been in equilibrium with the transporting komatiite lavas, and together with textural data indicate that much of the cumulus olivine in the sequence was transported. Flow top compositions show evidence for chromite saturation, but the cumulates are deficient in accumulated chromite. Chromite compositions are typical of those found in compound flow-facies komatiites, and are distinct from those in komatiitic dunite bodies. Incompatible trace element abundances show three superimposed influences: control by the relative proportion of olivine to liquid; a signature of crustal contamination and an overprint of metasomatic introduction of LREE, Zr and Th. This overprint is most evident in cumulates, and relatively insignificant in the spinifex rocks. Platinum and palladium behaved as incompatible elements and are negatively correlated with MgO. They show no evidence for wholesale depletion due to sulfide extraction, which was evidently restricted to specific lava tubes or pathways. The lack of correspondence between PGE depletion and contamination by siliceous material implies that contamination alone is insufficient to generate S-saturation and ore formation in the absence of sulfide in the assimilant. Contamination signatures in spinifex-textured rocks may be a guide to Ni-sulfide mineralisation, but are not entirely reliable in the absence of other evidence. The widespread vesicularity of the sequence may be attributable to assimilated water rather than to primary mantle-derived volatiles, and cannot be taken as evidence for primary volatile-rich magmas. The characteristic signature of the Black Swan Succession is the presence of highly localised disseminated sulfide within a sequence showing more widespread evidence for crustal contamination and interaction with its immediate substrate. This has important implications for the applicability of trace element geochemistry in exploration for komatiite-hosted nickel deposits.Electronic Supplementary Material Supplementary material is available in the online version of this article at Editorial handling: Peter Lightfoot