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141.
Helen Ruth Aspaas 《GeoJournal》2004,61(3):281-289
Women in many rural areas of the US often engage in small-scale businesses as one of several avenues for contributing to household
incomes. In those geographical areas that contain a significant minority population, many of the women's businesses display
the cultural diversity of the regions in which they live. Likewise, women's roles as economic providers as well as wives and
mothers are reflected in the manner in which they operate their businesses. Candida Brush suggests that women's strategies
for operating their businesses are highly integrative because women's business decisions are intertwined with familial responsibilities,
household economic demands and desires to contribute to their communities. Hispanic and Native American women in the Four
Corners region of southwestern US and African American women in central Virginia participated in interviews in which they
responded to numerous short answer and open-ended questions about their businesses and decision-making strategies. From these
interviews an image emerges of rural minority business women who are operating their businesses at the nexus of family obligations,
economic necessities, cultural ties and with a commitment for serving their communities.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
142.
143.
Precise/ Small Sample Size Determinations of Lithium Isotopic Compositions of Geological Reference Materials and Modern Seawater by MC-ICP-MS 总被引:6,自引:1,他引:6
Alistair B. Jeffcoate Tim Elliott Alex Thomas Claudia Bouman 《Geostandards and Geoanalytical Research》2004,28(1):161-172
The Li isotope ratios of four international rock reference materials, USGS BHVO-2, GSJ JB-2, JG-2, JA-1 and modern seawater (Mediterranean, Pacific and North Atlantic) were determined using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). These reference materials of natural samples were chosen to span a considerable range in Li isotope ratios and cover several different matrices in order to provide a useful benchmark for future studies. Our new analytical technique achieves significantly higher precision and reproducibility (< ± O.3%o 2s) than previous methods, with the additional advantage of requiring very low sample masses of ca . 2 ng of Li. 相似文献
144.
Oxygen isotope profiles along the growth axis of fossil bivalve shells of Macoma calcarea were established to reconstruct hydrographical changes in the eastern Laptev Sea since 8400 cal yr B.P.. The variability of the oxygen isotopes (δ18O) in the individual records is mainly attributed to variations in the salinity of bottom waters in the Laptev Sea with a modern ratio of 0.50‰/salinity. The high-resolution δ18O profiles exhibit distinct and annual cycles from which the seasonal and annual salinity variations at the investigated site can be reconstructed. Based on the modern analogue approach oxygen isotope profiles of radiocarbon-dated bivalve shells from a sediment core located northeast of the Lena Delta provide seasonal and subdecadal insights into past hydrological conditions and their relation to the Holocene transgressional history of the Laptev Sea shelf. Under the assumption that the modern relationship between δ18Ow and salinity has been constant throughout the time, the δ18O of an 8400-cal-yr-old bivalves would suggest that bottom-water salinity was reduced and the temperature was slightly warmer, both suggesting a stronger mixture of riverine water to the bottom water. Reconstruction of the inundation history of the Laptev Sea shelf indicates local sea level ∼27 m below present at this time and a closer proximity of the site to the coastline and the Lena River mouth. Due to continuing sea level rise and a southward retreat of the river mouth, bottom-water salinity increased at 7200 cal yr B.P. along with an increase in seasonal variability. Conditions comparable to the modern hydrography were achieved by 3800 cal yr B.P. 相似文献
145.
Models of late-glacial environmental change in coastal areas are commonly based on radiocarbon ages on marine shell and basal lake sediments, both of which may be compromised by reservoir effects. The magnitude of the oceanic reservoir age in the inland waters of the Georgia Basin and Puget Lowland of northwestern North America is inferred from radiocarbon ages on shell-wood pairs in Saanich Inlet and previously published estimates. The weighted mean oceanic reservoir correction in the early and mid Holocene is −720±90 yr, slightly smaller than, but not significantly different from, the modern value. The correction in late-glacial time is −950±50 yr. Valley-head sites yield higher reservoir values (−1200±130 yr) immediately after deglaciation. The magnitude of the gyttja reservoir effect is inferred from pairs of bulk gyttja and plant macrofossil ages from four lakes in the region. Incorporation of old carbon into basal gyttja yields ages from bulk samples that are initially about 600 yr too old. The reservoir age declines to less than 100 yr after the first millennium of lake development. When these corrections are accounted for, dates of deglaciation and late-glacial sea-level change in the study area are pushed forward in time by more than 500 yr. 相似文献
146.
The distribution of Sarcocornia pillansii (Moss) A.J. Scott was determined by water-table depth and electrical conductivity (EC) of the groundwater. Where the groundwater was accessible (<1.5 m) and had a low EC (<80 mS cm−1), S. pillansii extended its roots down to the water-table where a suitable water potential gradient was shown to exist between the soil and roots. In areas where the groundwater was too deep and/or hypersaline, the plants grew on hummocks. The unconfined aquifer below the floodplain is linked to the estuary and although diurnal tidal waves were dampened, water-table level fluctuations were recorded between tidal events. The complex geomorphology of the floodplain influences groundwater flow, in turn affecting the distribution of the salt marsh vegetation. 相似文献
147.
Ruth Lane Damian Lucas Frank Vanclay Sophie Henry Ian Coates 《The Australian geographer》2005,36(3):351-367
Emerging approaches to environmental governance require a greater level of community participation than did previous approaches in which these responsibilities largely rested with government agencies. There is consequently a need for increased engagement with NRM among a broad community sector. This paper examines initiatives by two prominent government agencies, the Murray–Darling Basin Commission (MDBC) and the National Museum of Australia (NMA), to engage school children from regional communities using education programs that focus on place and environmental health. We focus on the MDBC's International Riverhealth Conference held in Mildura in 2003 and the associated Murray–Darling Basin TalkBack Classroom sponsored by the NMA and the Parliamentary Education Office (PEO). We explore how key themes of local scale, place-based identities, youth voice and critical engagement are developed in these programs and consider how they relate to the environmental agency of children. We then reflect on the potential for the kinds of environmental agency promoted through these programs to help build the capacity of local communities to progress larger goals of environmental restoration and sustainability in the Murray–Darling Basin. The evaluation research reported here forms part of the Committing to Place research project, an Australian Research Council Linkage grant involving the University of Tasmania, the National Museum of Australia and the Murray–Darling Basin Commission. 相似文献
148.
Thomas R. Baker 《The Professional geographer》2005,57(1):44-50
Internet‐based mapping provides a powerful alternative for successfully establishing GIS technology in the K‐12 education community, while simultaneously avoiding the traditional barriers associated with desktop GIS. Internet‐based GIS can support standards‐based inquiry methods of teaching and learning while providing basic analysis tools for studying and exploring geographic or scientific data in the classroom. 相似文献
149.
Denitrification rates measured along a salinity gradient in the eutrophic Neuse River estuary, North Carolina, USA 总被引:2,自引:0,他引:2
John M. Fear Suzanne P. Thompson Thomas E. Gallo Hans W. Paerl 《Estuaries and Coasts》2005,28(4):608-619
Denitrification rates along a salinity gradient in the eutrophic Neuse River Estuary, North Carolina, were quantified using
membrane inlet mass spectrometry (MIMS) within short-term batch incubations. Denitrification rates within the system were
highly variable, ranging from 0 to 275 μmol N m−2 h−1. Intrasite variability increased with salinity, but no significant differences were observed across the salinity gradient.
Denitrification rates were positively correlated with sediment oxygen demand at the upstream sampling site where sediment
organic carbon levels were lowest. This relationship was not observed in the more saline sampling sites. Denitrification rates
were highest during winter. On an annual basis, denitrification accounted for 26% of the dissolved inorganic nitrogen and
12% of the total nitrogen supplied to the system. 相似文献
150.