Welfare reform and the intra-regional migration of beneficiaries in New Zealand

This paper investigates the net effect of major cuts in welfare benefits and associated changes in the delivery of housing assistance on the relocation behavior of beneficiaries. It does so against an international literature which has documented the tendency of welfare recipients to adjust their costs of living by moving from urban to rural settlements. The paper reviews the literature on welfare and migration, introduces a theoretical framework based on a metropolitan labour market and then tests several hypotheses about the possible effects of benefits cuts on spatial adjustment. The research design uses quinquennial census data to compare core beneficiary relocation patterns with those of non-beneficiaries before and after the cuts to welfare benefits in the Wellington region of New Zealand in 1991. The period following the benefit cuts in New Zealand was characterised by increasing job opportunities which helped to mitigate their adverse effect and made it difficult to identify a more general down-market residential adjustment. While a downward adjustment in housing consumption by core beneficiaries was identified, residential movement from urban to the cheaper settlements in adjacent rural areas was only observed from former State house areas where the income effects of benefit cuts were compounded by increases in rents on former State houses. Thus, while this paper supports the findings of independent sample survey work, our census based analysis underscores the highly contingent nature of that response. Evidence of urban-rural migration is placed in the context of the government's `remote area policy' which attempts to dissuade beneficiaries (who are receiving a social security benefit related to their employment status) from moving without good reason to `remote' locations where job prospects are weak. The paper raises the more general policy issue where benefit cuts, designed to stimulate more active job searching among the unemployed, actually prompt some beneficiaries to relocate to the urban fringe and in some cases to remote parts of the country where job prospects are weak. The theoretical and policy implication of this paper is that there are geographical correlates to the reservation wage which need to be integrated into thinking about the participation consequences of setting benefit levels.     

Constraints on element mobility associated with the conversion of granulite to eclogite along fractures in an anorthositic complex on Holsnøy, Norway

On Holsnøy, an island off the coast of Western Norway, an anorthositic complex metamorphosed to granulite facies was partially overprinted by a later eclogite facies metamorphism. Eclogite facies rocks (containing omphacite, garnet, kyanite and hydrous phases such as mica and zoisite) occur in shear zones of various scales and adjacent to veins. Previous studies of shear zones on Holsnøy reported evidence for substantial element mobility (Jamtveit et al ., 1990; Mattey et al ., 1994). In this work, we compare chemical compositions of granulite and its undeformed eclogitized equivalent adjacent to veins in locations where a single band of granulite can be traced and sampled as it approaches the vein. This tracing is crucial because the pre-granulite rocks cover a substantial compositional range, indicative of a petrologically variable protolith consisting of anorthosite, gabbro and jotunite. We analysed multiple core samples collected across nine separate granulite-eclogite transition zones located at veins in anorthositic, jotunitic and gabbroic protoliths for major and trace elements. For each transition, no compositional difference between the average granulite and average eclogite composition was found at the 90% confidence level except for LOI (loss on ignition), which was consistently significantly higher in the eclogite samples. Although not significant at the 90% confidence level for any single traverse, the average eclogite concentrations of SiO₂ , Na₂O, Cs, As and Br exceed the average granulite concentrations for eight or all nine of the traverses. For most traverses, statistical analysis of the data limits any gain of SiO₂ in the eclogites to no more than a few relative per cent. Other than the introduction of volatile substances, presumably an H₂O-rich fluid, eclogitization associated with vein formation was essentially isochemical.     

大陆碰撞和超高压变质的化学地球动力学:来自中国大陆科学钻探的结果

利用中国大陆科学钻探工程连续取样的优势,对主孔200～4000m超高压变质岩进行了系统的地球化学研究,结果对大陆俯冲带变质的化学地球动力学提供了新的制约。目前取得的主要成果如下:(1)建立了200～4000m深度的超高压矿物氧同位素变化剖面,发现~(18)O亏损深度达3300m。结合大别-苏鲁造山带地表露头岩石达30000km~2的~(18)O亏损,表明扬子陆块北缘曾发生三维空间巨量物质(～100000km~3)的~(18)O亏损;(2)钻孔超高压变质岩的原岩形成于新元古代中期(～780Ma),属于双重双峰式岩浆活动的产物;原岩既有中元古代晚期新生地壳,也有古元古代中期古老地壳。这种双重双峰式岩浆活动出现在弧-陆碰撞带基础上发育的裂谷构造带,是对Rodinia超大陆开始裂解的响应;(3)高压榴辉岩相重结晶作用发生在216±3Ma,高压榴辉岩相重结晶作用持续的时间为1.9～9.3Myr或更短;(4)不同岩性接触带的矿物O同位素、H同位素、全水含量以及羟基含量的研究表明,退变质流体在同位素组成上是内部缓冲的,且退变质流体主要来自于名义上无水矿物中结构羟基和分子水的出溶。定量计算表明,这些出溶的结构羟基和分子水能为角闪岩相退变质作用提供足够的流体来源;(5)在不同岩性接触带,稳定同位素、水含量及岩相学上出现同步变化,表明不同岩性接触带可能是流体活动最剧烈的地方。对于远离榴辉岩-片麻岩接触带的榴辉岩,退变质流体主要来自榴辉岩内部名义上无水矿物中结构羟基和分子水的出溶。对于靠近接触带的榴辉岩,则可能主要受来自比榴辉岩更富水的片麻岩中矿物的脱水作用。根据相邻样品之间的距离、岩相学和δ~(18)O值,可以确定出不同岩性和相同岩性之间氧同位素不均一性的尺度为20到50cm,对应于大陆碰撞过程中流体活动的最大尺度;(6)对两个连续岩芯段的主量和微量元素剖面研究表明,在大陆俯冲带变质过程中,大离子亲石元素(LILE)和轻稀土(LREE)具有较高的活动性,而高场强元素(HFSE)和重稀土(HREE)是不活动的。这些元素的活动可能是由折返过程中大陆地壳的部分熔融导致的,因此指示了超临界流体的出现。折返过程中大陆地壳的这种部分熔融作用导致了不同板片组分之间的质量迁移,但是这种有效的迁移只发生在很小的尺度范围内,在岩相学接触带和裂隙带的局部开放系统中。     

The storage of bed material in mountain stream channels as assessed using Optically Stimulated Luminescence dating

A detailed understanding of channel forming and maintenance processes in mountain streams requires some measurement and/or prediction of bed load transport and sediment mobility. Traditional field based measurements of such processes are problematic because of the high formative discharges characteristic of such streams. The application of Optically Stimulated Luminescence (OSL) dating is proposed here as a new way of determining actual residency times of fine sediments and consequently validating selected predictions for the entrainment of sediment in these streams. Model predictions of sediment mobility for selected step-pool and plane-bed channels in a mountain catchment in south eastern Australia are initially calculated using equations of hydraulic competence and the one-dimensional HEC-RAS model. Results indicate that floods exceeding bankfull with recurrence intervals up to 13 years are competent to mobilise the maximum overlying surface grain sizes at both sites. OSL minimum age model results from 7 samples of well bleached quartz in the fine matrix particles indicate general agreement with selected competence equations. The apparent long (100–1400 y) burial age of most of the mineral quartz, however, suggests that competent flows are not able to flush all subsurface fine-bed material. The depth of maximum bed load exchange (flushing) was limited to ≤ twice the depth of the overlying D₉₀ grain size. Application of OSL in this study provides important insight into the nature of storage and flushing of matrix material in mountain streams.     

The journey to school in Britain since the 1940s: continuity and change

The journey to school has major significance both for families and urban environments, yet little is known in detail about the ways this has changed over the twentieth century. This study uses oral history evidence to compare decisions about the journey to school in the past and the present, and to assess the impact of these changes on the mobility experience of children. The paper argues that despite obvious increases in car use, and decreases in children travelling alone, other characteristics of the journey to school in British urban areas have changed little over the past 60 years.     

Effects of volcanic eruptions on the CO2 content of the atmosphere and the oceans: the 1996 eruption and flood within the Vatnajökull Glacier, Iceland

The October 1996 eruption within the Vatnajökull Glacier, Iceland, provides a unique opportunity to study the net effect of volcanic eruptions on atmospheric and oceanic CO₂. Volatile elements dissolved in the meltwater that enclosed the eruption site were eventually discharged into the ocean in a dramatic flood 35 days after the beginning of the eruption, enabling measurement of 50 dissolved element fluxes. The minimum concentration of exsolved CO₂ in the 1×10¹² kg of erupted magma was 516 mg/kg, S was 98 mg/kg, Cl was 14 mg/kg, and F was 2 mg/kg. The pH of the meltwater at the eruption site ranged from about 3 to 8. Volatile and dissolved element release to the meltwater in less than 35 days amounted to more than one million tonnes, equal to 0.1% of the mass of erupted magma. The total dissolved solid concentration in the floodwater was close to 500 mg/kg, pH ranged from 6.88 to 7.95, and suspended solid concentration ranged from 1% to 10%. According to H, O, C and S isotopes, most of the water was meteoric whereas the C and S were of magmatic origin. Both C and S went through isotopic fractionation due to precipitation at the eruption site, creating “short cuts” in their global cycles. The dissolved fluxes of C, Ca, Na, Si, S and Mg were greatest ranging from 1.4×10¹⁰ to 1.4×10⁹ mol. The dissolved C flux equaled 0.6 million tonnes of CO₂. The heavy metals Ni, Mn, Cu, Pb and Zn were relatively mobile during condensation and water–rock interactions at the eruption site. About half of the measured total carbon flood flux from the 1996 Vatnajökull eruption will be added to the long-term CO₂ budget of the oceans and the atmosphere. The other half will eventually precipitate with the Ca and Mg released. Thus, for eruptions on the ocean floor, one can expect a net long-term C release to the ocean of less than half that of the exsolved gas. This is a considerably higher net C release than suggested for the oceanic crust by Staudigel et al. [Geochim. Cosmochim. Acta, 53 (1989) 3091]. In fact, they suggested a net loss of C. Therefore, magma degassed at the ocean floor contributes more C to the oceans and the atmosphere than magma degassed deep in the oceanic crust. The results of this study show that subglacial eruptions affecting the surface layer of the ocean where either Mn, Fe, Si or Cu are rate-determining for the growth of oceanic biomass have a potential for a transient net CO₂ removal from the ocean and the atmosphere. For eruptions at high latitudes, timing is crucial for the effect of oceanic biota. Eruptions occurring in the wintertime when light is rate-determining for the growth of biota have much less potential for bringing about a transient net negative CO₂ flux from the ocean atmosphere reservoir.     

南秦岭古生代沉积岩的地球化学特征及其反映的区域地壳活动性

各类地质体的地球化学特征是地球物质化学运动的记录。深部岩石圈层次卷入地表地质作用的程度反映区域地壳的活动性。古生代南秦岭的区域地壳活动性在早古生代有增强的趋势，晚古生代则又逐渐减弱，以志留纪早期区域地壳活动性最强；空间上以紧邻松潘－甘孜地块的康县－褒河小区和紧邻扬子克拉通北缘的紫阳－竹溪小区构成的近东西向狭长地带区域地壳活动性最强，而且东西两段各有特色。这种区域地壳活动性的时空变化格局可能与新元古代至早古生代松潘－甘孜与扬子联合大陆北部边缘的地壳伸展及早古生代末与华北地台的碰撞拼合有关。     

Daily and Periodic Mobility Patterns of the Urban Homeless*

The intraurban mobility patterns of a sample of homeless individuals in the Skid Row area of Los Angeles is examined. Findings indicate that the voluntary mobility of homeless persons in the sample is related less to individual characteristics than to the availability and location of resources, particularly social supports.     

The enigma of social sustainability in rural Australia

While much previous work has been done on the general concept of ecological sustainability, there is relatively little that examines the likely spatial aspects of a socially sustainable rural system. Having defined essential concepts, this study first identifies major current forces for rural change likely to influence any future sustainable system. It goes on to specify those features of modern rural social formations which I believe deserve retention. Finally, some essential requirements for a socially sustainable system are established.