A century of inequality in England and Wales using standardized geographical units

This paper analyses geographical trends in relative poverty in England and Wales over the last century by comparing key quantitative indicators from key dates. The comparison is made possible by interpolating all the datasets onto a single standardized geography. Results suggest rising inequality in spite of the decline in absolute poverty.     

Morphometric Controls and Basin Response in The Cascade Mountains

Morphometric variables associated with 36 debris torrent, 78 snow avalanche, 45 composite debris torrent and snow avalanche and 14 streamflow basins in the Cascade Mountains of southwestern British Columbia, Canada are examined. The results show significant statistical differences in top and bottom elevations, relief, channel length and gradient, basin area, fan gradient and area, and basin ruggedness between snow avalanche basins and the two basin types affected by debris torrents, reflecting the very different nature of these processes. Only top and bottom elevations and fan area differ significantly between debris torrent and debris torrent-snow avalanche basins, implying that the latter are probably debris torrent basins in origin. As many as six morphometric variables are significantly different between streamflow basins and the other basin types, allowing the former to be differentiated despite their small, steep character. Discriminant analysis indicates that bottom elevation and channel or path gradient are the best variables for classifying the four basin types by process. Generally strong correlations exist between basin area on the one hand and relief, channel length and channel gradient on the other in debris torrent, debris torrent-snow avalanche, and streamflow basins. Fan gradient and area are, however, weakly or modestly correlated with basin area or ruggedness. No such morphometric relations are present in snow avalanche basins. The results of this study also indicate that in debris torrent-prone basins the fan gradient and Melton's R have identifiable lower thresholds while basin area has an upper threshold, but use of these thresholds for identification of debris torrent hazard is complicated by overlapping thresholds for streamflow basins.     

Impact of prescribed burning on Acacia nilotica seed banks and seedlings in the Astrebla grasslands of northern Australia

Acacia nilotica is a tree of international significance both as a beneficial plant and as a species prone to thicket formation and negative impacts on savannas throughout much of its range. While fire has been identified as a useful tool for controlling negative impacts of some Acacia species in Africa, A. nilotica adult trees are apparently fire tolerant. The effects of fire on seed bank mortality, viability and germination, and on juvenile plants of this species are unknown. We undertook a study to investigate the impacts of fire on seeds and first and second year seedlings in Australian Astrebla savannas. The primary objective was to determine the effects of control burns applied during the early stages of invasion and thicket formation. Because of high rates of seedling dessication post fire in 1997, supplementary watering was undertaken until fire mortality could be measured the following year. High seed mortality occurred for seeds located either in cattle dung (100%) or on the soil surface (c. 80%). Germination of those seeds that survived was enhanced following exposure to fire. Very high fire mortality (99%) was observed among first year seedlings and moderate mortality (60%) for second year seedlings even after a low intensity burn. Negative impacts on major pasture species were minimal. The implications of these findings are discussed in relation to A. nilotica fire ecology and to the efficacy of fire as a tool for managing this species.     

Jorvik MIST – 2001

The magnetosphere, ionosphere and solar–terrestrial physics community gathered at the Department of Chemistry, University of York from 9–11 April 2001. Neil Arnold and Ian Mann report.     

Microbial–silica interactions in Icelandic hot spring sinter: possible analogues for some Precambrian siliceous stromatolites

Silicified deposits, such as sinters, occur in several modern geothermal environments, but the mechanisms of silicification (and crucially the role of microorganisms in their construction) are still largely unresolved. Detailed examination of siliceous sinter, in particular sections of microstromatolites growing at the Krisuvik hot spring, Iceland, reveals that biomineralization contributes a major component to the overall structure, with approximately half the sinter thickness attributed to silicified microorganisms. Almost all microorganisms observed under the scanning electron microscope (SEM) are mineralized, with epicellular silica ranging in thickness from < 5 μm coatings on individual cells, to regions where entire colonies are cemented together in an amorphous silica matrix tens of micrometres thick. Within the overall profile, there appears to be two very distinct types of laminae that alternate repeatedly throughout the microstromatolite: ‘microbial’ layers are predominantly consisting of filamentous, intact, vertically aligned, biomineralized cyanobacteria, identified as Calothrix and Fischerella sp.; and weakly laminated silica layers which appear to be devoid of any microbial component. The microbial layers commonly have a sharply defined base, overlying the weakly laminated silica, and a gradational upper surface merging into the weakly laminated silica. These cyclic laminations are probably explained by variations in microbial activity. Active growth during spring/summer allows the microorganisms to keep pace with silicification, with the cell surfaces facilitating silicification, while during their natural slow growth phase in the dark autumn/winter months silicification exceeds the bacteria’s ability to compensate (i.e. grow upwards). At this stage, the microbial colony is probably not essential to microstromatolite formation, with silicification presumably occurring abiogenically. When conditions once again become favourable for growth, recolonization of the solid silica surface by free‐living bacteria occurs: cell motility is not responsible for the laminations. We have also observed that microbial populations within the microstromatolite, some several mm in depth, appear viable, i.e. they still have their pigmentation, the trichomes are not collapsed, cell walls are unbroken, cytoplasm is still present and they proved culturable. This suggests that the bulk of silicification occurred rapidly, probably while the cells were still alive. Surprisingly, however, measurements of light transmittance through sections of the microstromatolite revealed that photosynthetically active light (PAL) only transmitted through the uppermost 2 mm. Therefore the ‘deeper’ microbial populations must have either: (i) altered their metabolic pathways; (ii) become metabolically inactive; or (iii) the deeper populations may be dominated by different microbial assemblages from that of the surface. From these collective observations, it now seems unequivocal that microstromatolite formation is intimately linked to microbial activity and that the sinter fabric results from a combination of biomineralization, cell growth and recolonization. Furthermore, the similarities in morphology and microbial component to some Precambrian stromatolites, preserved in primary chert, suggests that we may be witnessing contemporaneous biomineralization processes and growth patterns analogous to those of the early Earth.     

Dolomitization of the Waulsortian Limestone (Lower Carboniferous) in the Irish Midlands

The Waulsortian Limestone (Lower Carboniferous) of the southern Irish Midlands is dolomitized pervasively over a much larger region than previous studies have documented. This study indicates a complex, multistage, multiple fluid history for regional dolomitization. Partially and completely dolomitized sections of Waulsortian Limestones are characterized by finely crystalline (0·01–0·3 mm) planar dolomite. Planar replacive dolomite is commonly followed by coarse (≥0·5 mm) nonplanar replacive dolomite, and pervasive void‐filling saddle dolomite cement is frequently associated with Zn–Pb mineralization. Planar dolomite has average δ¹⁸O and δ¹³C values (‰ PDB) of –4·8 and 3·9 respectively. These are lower oxygen and slightly higher carbon isotope values than averages for marine limestones in the Waulsortian (δ¹⁸O=–2·2, δ¹³C=3·7). Mean C and O isotope values of planar replacive dolomite are also distinct from those of nonplanar and saddle dolomite cement (–7·0 and 3·3; –7·4 and 2·4 respectively). Fluid inclusions indicate a complex history involving at least three chemically and thermally distinct fluids during dolomite cementation. The petrography and geochemistry of planar dolomites are consistent with an early diagenetic origin, possibly in equilibrium with modified Carboniferous sea water. Where the Waulsortian was exposed to hydrothermal fluids (70–280 °C), planar dolomite underwent a neomorphic recrystallization to a coarser crystalline, planar and nonplanar dolomite characterized by lower δ¹⁸O values. Void‐filling dolomite cement is isotopically similar to nonplanar, replacive dolomite and reflects a similar origin from hydrothermal fluids. This history of multiple stages of dolomitization is significantly more complex than earlier models proposed for the Irish Midlands and provides a framework upon which to test competing models of regional vs. localized fluid flow.     

The beachwatch pollution monitoring programme: Changing priorities to recognize changed circumstances

Since the commissioning of the three major deepwater outfalls in Sydney, there has been a dramatic improvement in general beach water quality at Sydney's ocean beaches. This has required the NSW Environment Protection Authority's Beachwatch Programme to shift from assessing the impacts of gross sewage pollution due to nearshore outfalls to more diffuse pollution from stormwater and sewer overflows.

The visual indicators of gross sewage pollution originally used by Beachwatch for the daily assessment of bacterial water quality are now of limited value. General linear models (with multiple effects) were constructed to identify the secondary indicators which best describe the levels of bacterial contamination due to stormwater pollution. Data from four representative Sydney beaches were modelled separately due to the site-specific effects of pollution sources and hydrodynamics. Factors which were built into the models and were known on the day of prediction were rain amount, presence of stormwater material, the maximum daily stormwater rating, drain or lagoon flows at the time of sampling, and the drain/lagoon bacterial concentration two days before sampling.

Results indicate that there is a general linear relationship between visual indicators and bacterial density; however, the reliability of the prediction on a daily basis is poor and rainfall alone as a predictor is equivalent to or better than visual assessment alone. The primary source of information for the preparation of Beachwatch daily pollution bulletins now is rainfall reports from a telemetered network of rain gauges along the coast. This is a more cost-effective approach and has allowed the reallocation of resources to address more directly the problem of stormwater pollution at higher risk beaches.     

Morphological characteristics of the earthquake surface ruptures on Awaji Island, associated with the 1995 Southern Hyogo Prefecture Earthquake

Abstract The earthquake surface ruptures on the northern side of Awaji Island accompanying the 1995 Southern Hyogo Prefecture Earthquake in Japan consist of three earthquake surface rupture zones called the Nojima, Matsuho, and Kusumoto Earthquake Surface Rupture Zones. The Nojima Earthquake Surface Rupture Zone is - 18 km long and was formed from Awaji-cho at the northern end of Awaji Island to Ichinomiya-cho. It occurred along the pre-existing Nojima geological fault in the northern segment and as a new fault in the southern segment. The northern segment of the Nojima Earthquake Surface Rupture Zone is composed of some subparallel shear faults showing a right-step en echelon form and many extensional cracks showing a left-step en echelon form. The southern segment consists of some discontinuous surface ruptures which are concentrated in a narrow zone a few tens of meters in width. This surface rupture zone shows a general trend striking north 30°-60° east, and dipping 75°-85° east. The deformational topographies and striations on the fault plane generated during the co-seismic displacement show that the Nojima Earthquake Surface Rupture Zone is a right-lateral strike-slip fault with some reverse component. Displacements measured at many of the outcrops are generally 100-200 em horizontally and 50-100 em vertically in the northern segment and a few em to 20 em both horizontally and vertically in the southern segment. The largest displacements are 180 em horizontally, 130 em vertically, and 215 em in netslip measured at the Hirabayashi fault scarp. The Matsuho Earthquake Surface Rupture Zone striking north 40°-60° west was also found along the coastline trending northwest-southeast in Awaji-cho for ～1 km at the northern end of Awaji Island. The Kusumoto Earthquake Surface Rupture Zone occurred along the pre-existing Kusumoto geological fault for ～ 1.5 km near the northeastern coastline, generally striking north 35°-60° east, dipping 60°-70° west. From the morphological and geomorphological characteristics, the Nojima Earthquake Surface Rupture Zone can be divided into four segments which form a right-step en echelon formation. The geological and geomorphological evidence and the aftershock epicenter distributions show clearly that the distributions and geometry of these four segments are controlled by the pre-existing geological structures.     

Deuterium tracing for the estimation of transpiration from trees Part 1. Field calibration

Flow rates calculated using the deuterium tracing method were compared with measurements of direct water uptake of excavated trees which had been inserted into water containers. Taking into account that the tracing method provides an estimate of the weighted mean flow rate over the period that the tracer pulse is present (the weighting factor is the relative concentration of the tracer as measured at the sampling point) agreement was obtained within the experimental error (about 10%) associated with the tracing method.