Identification of soil erosion and fluvial sediment problems

A computer model has been used to estimate soil loss and sediment yield from irregular field-size units of small watersheds. Input to the model includes spring data (i.e. relating to February through May) for the independent variables of the Universal Soil Loss Equation, and for factors such as surface roughness, an index of overland runoff, and proximity to the stream. Output from the model includes maps of seasonal estimates of potential soil losses, field sediment delivery ratios, and expected sediment yields. On the basis of selected erosion and sediment yield tolerances, the output information has been analysed to identify watershed areas which (1) exhibit both erosion and sediment yield problems; (2) exhibit only erosion problems; (3) exhibit only sediment yield problems; and (4) exhibit neither erosion nor sediment yield problems. The percentage of the watershed area in each category and the percentage of the watershed soil loss and sediment loads contributed by each category are also identified. Application of the procedure for planning remedial control programs for five watersheds is discussed.     

Small-scale, nature-based tourism as a pro-poor development intervention: Two examples in Kwazulu-Natal, South Africa

Tourism is widely acknowledged as a key economic sector that has the potential to contribute to national and local development and, more specifically, serve as a mechanism to promote poverty alleviation and pro-poor development within a particular locality. In countries of the global South, nature-based tourism initiatives can make a meaningful impact on the livelihoods of the poor, in particular the subsistence based rural poor. Taking two examples in KwaZulu-Natal Province, South Africa, where small-scale tourism initiatives were developed recently in response to existing natural attractions in the context of coping with local economic crises, this paper broadly assesses the modest benefits to date, as well as drawbacks, in improving conditions of life.     

Crystallization of calc-alkaline andesite under controlled high-pressure hydrous conditions

A series of experimental runs has been conducted on a glass prepared from a natural island are calc-alkaline andesite from Fiji. The crystallization sequence was determined for the pressure interval 9–36 kb under anhydrous conditions and with 2, 5, and 10% by weight of water carefully added. Addition of water markedly lowers the liquidus, depresses the appearance of quartz and plagioclase in the crystallization sequence, and greatly enlarges the field of garnet-clinopyroxene crystallization above 25 kb. Amphibole crystallizes in hydrous runs up to 25 kb. Electron microprobe analyses of critical phases allows calculation of controls on crystal fractionation trends. For hydrous conditions at 5–15 kb amphibole-clinopyroxene dominate fractionation and a moderate decrease in Mg/Fe and a slight increase in K/Na occurs. At 15–25 kb garnet also affects the fractionation and a moderate decrease in Mg/Fe and an increase in K/Na results. Above 25 kb garnet-clinopyroxene control the fractionation and there is a slight decrease in Mg/Fe but a significant increase in K/Na and a pronounced silica enrichment. In terms of major element chemistry, the derivation of the Fijian dacites in the second period of eruption may be satisfactorily explained by the fractionation of hydrous andesite at pressures >25 kb. Alternatively the dacites may result from lower degrees of melting of the down-going hydrous lithosphere. Similarly other members of this eruptive period may be derived according to a model of eclogite-controlled fractional melting or crystallization. Models involving amphibole fractionation at lower pressures are less satisfactory for explaining compositions in the Fijian second period of eruption, but in other environments models including amphibole-controlled fractionation may form part of a continuum of melting processes in subduction zones.     

Herschel SPIRE fourier transform spectrometer: calibration of its bright-source mode

The Fourier Transform Spectrometer (FTS) of the Spectral and Photometric Imaging REceiver (SPIRE) on board the ESA Herschel Space Observatory has two detector setting modes: (a) a nominal mode, which is optimized for observing moderately bright to faint astronomical targets, and (b) a bright-source mode recommended for sources significantly brighter than 500 Jy, within the SPIRE FTS bandwidth of 446.7–1544 GHz (or 194–671 microns in wavelength), which employs a reduced detector responsivity and out-of-phase analog signal amplifier/demodulator. We address in detail the calibration issues unique to the bright-source mode, describe the integration of the bright-mode data processing into the existing pipeline for the nominal mode, and show that the flux calibration accuracy of the bright-source mode is generally within 2 % of that of the nominal mode, and that the bright-source mode is 3 to 4 times less sensitive than the nominal mode.     

Herschel SPIRE FTS spectral mapping calibration

The Herschel SPIRE Fourier transform spectrometer (FTS) performs spectral imaging in the 447–1546 GHz band. It can observe in three spatial sampling modes: sparse mode, with a single pointing on sky, or intermediate or full modes with 1 and 1/2 beam spacing, respectively. In this paper, we investigate the uncertainty and repeatability for fully sampled FTS mapping observations. The repeatability is characterised using nine observations of the Orion Bar. Metrics are derived based on the ratio of the measured intensity in each observation compared to that in the combined spectral cube from all observations. The mean relative deviation is determined to be within 2 %, and the pixel-by-pixel scatter is ～ 7 %. The scatter increases towards the edges of the maps. The uncertainty in the frequency scale is also studied, and the spread in the line centre velocity across the maps is found to be ～ 15 km s ^{? 1}. Other causes of uncertainty are also discussed including the effect of pointing and the additive uncertainty in the continuum.     

Seasonal variability of rainfall extremes

Monthly rainfall extremes have been analyzed for three stations in Southern Ontario. The double exponential probability distribution was fitted to the extreme values for each month considered, each duration selected, and sets of annual extremes. A station‐year approach yielded monthly and annual extreme value distributions for the lumped region of Southern Ontario. The analysis has revealed a pronounced seasonal pattern in the rainfall extremes – the amount of rain expected with a selected probability of occurrence during the summer being considerably greater than the rainfall that might be expected to be exceeded at the same probability level during the spring or fall. The extent of the seasonal variability was found also to vary with duration. The implications of the variability are seen to be significant for the estimation of the magnitude and frequency of floods.     

Heavy Metal Concentrations in European Mosses: 2000/2001 Survey

The heavy metals in mosses survey was originally established in 1980 as a joint Danish–Swedish initiative under the leadership of Åke Rühling, Sweden and has, since then, been repeated at five-yearly intervals with an increasing number of countries and individuals participating. Twenty-eight European countries, almost 7000 sites and about 100 individuals have been involved in the most recent survey in 2000/2001. The survey provides data on concentrations of 10 heavy metals (arsenic, cadmium, chromium, copper, iron, lead, mercury, nickel, vanadium, zinc) in naturally growing mosses throughout Europe. The technique of moss analysis provides a surrogate measure of the spatial patterns of heavy metal deposition from the atmosphere to terrestrial systems, and is easier and cheaper than conventional precipitation analysis. The aims of the survey are to determine patterns of variation in the heavy metal concentration of mosses across Europe, identify the main polluted areas, produce regional maps and further develop the understanding of long-range transboundary pollution.As in previous surveys, there was an east/west decrease in heavy metal concentrations in mosses, related in particular to industrial emissions. Former industrial sites and historic mines accounted for the location of some high concentrations in areas without contemporary industries. Long-range transboundary transport appears to account for elevated concentrations of heavy metals in areas without emission sources, such as lead in southern Scandinavia (presumably from emission sources elsewhere in Europe).     

Sources of sand tempers in prehistoric Tongan pottery

The sources of volcanic temper sands in prehistoric pottery found on low-lying raised-coral islands of Tonga have long been uncertain. The paucity of noncalcareous sand on most inhabited Tongan islands has led to the suggestion that temper was imported from the active magmatic are to the west, or even that most pottery was imported to Tonga from Fiji. The simple mineralogy of the tempers, which are composed almost exclusively of pyroxene and plagioclase mineral grains, volcanic rock fragments, and opaque ferro-magnesian oxide grains, is compatible with derivation from Tongan volcanics, but island volcanoes of Tonga lack deposits of rounded and well-sorted sands that are similar texturally to the tempers. Discovery of local placer deposits composed of volcanic sand on beaches otherwise composed of calcareous reef detritus within the Ha'apai Group of central Tonga provides a satisfactory local source for temper on the shorelines of several inhabited islands. The beach placer sands were apparently derived from reworking of thick tephra deposits that mantle the islands. Detailed compositional analysis of temper sands in numerous ancient Lapitoid potsherds from all the constituent island groups of Tonga implies that pottery making was once a widespread industry making use of locally available raw materials. Stylistically diagnostic protohistoric Fijian potsherds, found in small numbers on several islands in Tonga, can be distinguished from the older indigenous Lapitoid wares by their anomalous tempers, which contrast sharply with the Tongan volcanic temper sands. © 1996 John Wiley & Sons, Inc.     

Petrography and geologic provenance of sand tempers in prehistoric potsherds from Fiji and Vanuatu,South Pacific

Indigenous sand tempers in prehistoric potsherds from Fiji, Vanuatu, and neighboring islands of the eastern Solomon outliers and northern Melanesian borderland have diverse compositions reflecting the varied geology of different islands in patterns controlled by regional geotectonic relations. Mineralogical compositions of noncalcareous temper sands reflect the nature of the bedrock sources on different islands. Temper analysis indicates that the ceramic assemblages recovered from most archaeological sites within the region were made locally or nearby, but also documents interisland ceramic transfer in widely varying volumes over distances as much as several hundred kilometers. Contrasts in island geology allow exotic wares to be identified without ambiguity but to varying degrees of specificity in terms of islands of origin. Rare sherds of New Caledonian wares have been collected in prehistoric context from several islands in Vanuatu, but there is as yet no temper evidence for prehistoric ceramic transfer between Vanuatu and Fiji. © 2001 John Wiley & Sons, Inc.