bluuebunny/crossref_metadata_2025_split huggingface dataset:
Survival of Mayfly Larvae Under Mine Acid Conditions
Authors: Napier Stanley , Hummon William D. 
Published: February 2007

AbstractMayfly larvae were abundant and diverse in riffle zones of three control streams in southeastern Ohio. But none were found in such zones of three streams having current or past histories of mine acid pollution, despite vegetative recovery of reclaimed land bordering two of the streams.Laboratory studies showed stepwise increases in non‐predatory mortality of mayfly larvae with increased mine acidity. Dragonfly larvae predation on mayfly larvae was constant at pH 8.1–4.1, but decreased at pH 3.1 despite tolerance of dragonfly larvae to low pH conditions. Extensive acid mine pollution thus may threaten aquatic biota through removal of food sources or reduced feeding rates as well as through direct mortality.
Subsurface Chlorophyll Maximum and Associated Cyclotella Pulse in Lake Superior
Authors: Fahnenstiel Gary L. , Glime Janice 
Published: February 2007

AbstractAn investigation of the subsurface chlorophyll layer (SCL) in Lake Superior was conducted from 1 May through 15 October. During spring unstratified conditions (1 May–17 July), chlorophyll a and phytoplankton biomass were vertically and temporally uniform. Phytoflagellates such as Rhodomonas minuta, Cryptomonas spp., and Ochromonas spp. were dominant at this time. The photosynthetic maximum was associated with the depth receiving 10% of surface irradiance, ca. 15–25 m. Once thermal stratification occurred, a SCL developed around 20 m. Although epilimnetic chlorophyll concentrations remained similar to spring mixing levels, concentrations in the SCL increased 3‐fold. In situ production was the principal process associated with the development of the SCL. The upper portion of the SCL was dominated by Cyclotella species; C. stelligera, C. comensis, and C. ocellata. The increased abundance of Cyclotella appeared to be related to stable irradiance fields produced during thermal stratification.
Evaluation of Succession in an Estuarine Macrobenthic Soft‐Bottom Community near Tampa, Florida
Authors: Santos Stuart L. , Bloom Stephen A. 
Published: February 2007

AbstractA subtidal macrobenthic infaunal community was quantitatively sampled monthly from February 1975 to July 1978 (42 months). During that period, complete defaunation (presumably due to hypoxia) occurred three times at approximately annual intervals. The recovery of the community was examined for successional patterns by quantitative and qualitative normal and inverse classification analyses and by rank‐order analysis of the dominant species. There was no consistent pattern of succession from recovery to recovery. Samples taken just after defaunation were not similar to each other and no consistent suites of species were detected. Classical succession in which suites of species are successively replaced by other suites until a persisting suite of species occurs (faciliation model) was not found. Other models of succession are discussed.
Trace Metal and PCB Content of Mussels (Mytilus edulis) from the Southwestern Baltic Sea
Authors: Möller Heino , Schneider Rolf , Schnier Christian 
Published: February 2007

AbstractThe concentrations of polychlorinated biphenyls and 28 metals were determined in mussels from 32 stations in the southwestern Baltic Sea. Elevated levels of PCBs (up to 28 mg/kg lipids) were found in harbour areas. Increased amounts of some metal contaminants were found in three large areas. The discharge from a sewage plant is responsible for high residues at stations in the outlet of Kiel Fjord. Increased levels of heavy metals in the outer Flensburg Fjord and in the vicinity of Fehmarn Sound seem to be due to natural geological formations, as indicated by the occurrence of elements that usually are not found at high concentrations in anthropogenic wastewaters.
A Comparative Study of Respiration Rates of Some Aquatic Oligochaetes in Relation to Sublethal Stress
Authors: Brinkhurst Ralph O. , Chapman Peter M. , Farrell Melody A. 
Published: February 2007

AbstractAquatic oligochaete species selected on the basis of pollution tolerance or intolerance as determined from field studies were used to determine respiration rates under standard conditions, after exposure to sublethal levels of environmental variables (pH, salinity, temperature) or toxicants (Cd, Hg, NaPCP) alone or in pairs. Respiration rates, critical oxygen levels and degree of regulation were not correlated with field‐determined tolerance to organic pollution. Stress factors caused increased or lowered respiration rate, loss of regulation (partial or total) and sometimes shifts in critical oxygen level. Regulation was improved in the face of some stresses. Combined stresses produced additional changes in respiration rates and regulation. These responses were complex, which makes them useful indicators of specific stress factors but also indicate complex mechanisms behind the observed changes.
Qualitative and Quantitative Entomofaunistic Investigation of an Opencast Residual Lake near Leipzig (GDR)
Authors: Jacob Udo , Klausnitzer Bernhard , Walther Hendrik 
Published: February 2007

AbstractIn the Kulkwitz opencast residual lake, which has existed since 1962 in the Leipzig lignite district (GDR), the physico‐chemical characteristics of water were recorded and qualitative and quantitative entomofaunistic inventories carried out. For the latter, a floating emergence trap was used, which caught a total of 8,397 insects above a water area of 2.25 m2 during the summer and autumn of 1979. These insects belong to 12 families and 4 orders. Dominances, diversities and equities were determined for the Trichoptera. The results were compared with those obtained in the acid Olba opencast residual lake northeast of Bautzen, which was investigated at the same time of year.
Responses of the Phytoplankton Community of a Tropical Reservoir (São Paulo, Brazil) to the Enrichment with Nitrate, Phosphate and EDTA
Authors: Henry Raoul , Tundisi José Galizia 
Published: February 2007

AbstractThe effects of artificial enrichment with nitrate, phosphate and EDTA on the phytoplankton community were studied in the Lobo Reservoir (São Paulo, Brazil). After 14 days of in situ incubation, the amounts of suspended matter and chlorophyll a, the numbers of cells and the carotene/chlorophyll ratio were determined. The addition of nitrate and phosphate to water samples produced significant effects on the chlorophyll a and cell counts, while EDTA acted only on the cell production. Both nitrate and phosphate, when analysed individually, caused a decrease in the value of the carotene/chlorophyll ratio. A synergistic effect of the addition of EDTA and N on the suspended matter was observed.
Assessment of δ13C and C/N ratios in bulk organic matter as palaeosalinity indicators in Holocene and Lateglacial isolation basin sediments, northwest Scotland
Authors: Mackie Elizabeth A. V. , Lloyd Jeremy M. , Leng Melanie J. , Bentley Michael J. , Arrowsmith Carol 
Published: February 2007

AbstractCarbon isotopes (δ13C) and C/N ratios from bulk organic matter have recently been used as alternative proxies for relative sea‐level (RSL) reconstruction where there are problems associated with conventional biological indictors. A previous study on a single isolation basin (Upper Loch nan Eala) in northwest Scotland has shown a clear relationship between δ13C, C/N ratios and palaeosalinity from Younger Dryas and Holocene aged sediments. In this paper we present results of δ13C and C/N ratio analyses from other isolation basins in northwest Scotland over the Holocene and the Lateglacial period in order to validate this technique. The results from the Holocene sequences support the earlier findings that this technique can be used to identify RSL change from isolation basins over the Holocene in this region. The relationship between δ13C, C/N ratios and RSL change is not apparent in sediments of Lateglacial age. Other environmental variables such as atmospheric CO2 concentration, poor vegetation development and temperature influence δ13C values during this period. Copyright © 2007 John Wiley & Sons, Ltd.
Monitoring derelict urban land: A review of problems and potentials of remote sensing techniques
Authors: Kivell P. T. , Parsons A. J. , Dawson B. R. P. 
Published: February 2007

AbstractThe accelerating rate of change in urban areas calls for more rapid and cost‐effective surveys of derelict land. A review of the use of remote sensing1 for this task reveals that, although aerial photography has been used for urban analysis since the 1940s, it has not been widely adopted for surveys of derelict land, despite demonstrations of its utility. Other forms of remote sensing are similarly shown to have been little‐used and to have had patchy success. The hitherto restricted utility of remote sensing is found to be due to a combination of limitations of the forms of imagery available and the methods of analysis employed. Recent changes in available remote sensing imagery, notably the higher resolution now provided by the SPOT satellite, coupled with advances in digital image‐processing techniques point to improved opportunities for using remote sensing to monitor derelict land. As a demonstration of these developments, a texture image based on scene variance is derived from a SPOT image of part of north Staffordshire. All derelict and neglected land parcels larger than 1.25 ha are delimited on this image. Remote sensing techniques are not yet ready to supplant detailed ground surveys but they have a growing role to play in monitoring various aspects of land dereliction.
Transport processes for chernobyl‐labelled sediments: Preliminary evidence from upland mid‐wales
Authors: Bonnett P. J. P. , Leeks G. J. L. , Cambray R. S. 
Published: February 2007

AbstractThe nuclear accident at Chernobyl in April 1986 resulted in a significant increase in the inventory of radiocaesium retained in the soil in many regions of the United Kingdom. The deposition of 134Cs provides a convenient tool for the examination of erosional processes in upland systems. Detailed soil sampling has been undertaken within the Plynlimon experimental catchments to establish the pattern of deposition of Chernobyl‐derived radionuclides. The preliminary results of a combined radiometric and mineral magnetic approach to the study of the transport of Chernobyl‐labelled sediments and their source areas on these upland catchments in mid‐Wales are described.
Long‐term consequences of topsoil mining on select biological and physical characteristics of two New Zealand loessial soils under grazed pasture
Authors: Hart P. B. S. , August J. A. , West A. W. 
Published: February 2007

AbstractSoil chemical, biochemical, biological and structural properties were measured in two New Zealand loessial soils that were topsoil‐mined 10 and 25 years ago respectively. Measurements at the 10‐year site were compared to some earlier measurements made at this site and the data combined in a chronological sequence for analysis. Topsoil mining had a large, detrimental impact on the soil microbial biomass, the earthworm populations, easily mineralizable N and soil enzyme activities. However, most of these properties substantially recovered, to 80‐90 per cent of the levels in unmined soils, within 10‐25 years of restoration under pasture. In contrast, while total soil C and N were less affected by topsoil mining, their recovery was much slower. Stabilities of macro‐aggregates of soil had fully recovered within 10‐25 years after topsoil mining. The apparent changes in all the measured properties between 10 and 25 years of restoration were small in comparison with changes between 0‐10 years of restoration after topsoil mining. The total C content of both soils under pasture appeared unlikely to attain the levels present in unmined soils. In soils undergoing restoration, the ratio of microbial C/total soil C may be a useful index of soil ‘biological stability’. Sulphatase activity may reflect the recovery of pasture production.
Small farm production in dominica, West Indies: A strategy for survival
Authors: Reading A. J. , Soussan J. 
Published: February 2007

AbstractCalls for sustainable development have emerged largely because of the failure of technology‐focused, production‐orientated development policies to address the acute rural poverty and deteriorating environments of much of the Third World. Increased agricultural production through greater commercialization has a mirror image of decreasing incomes for the rural poor as market penetration undermines the viability of traditional production systems. These production systems are geared to minimizing risk through the harnessing of the full range of local resources, both private and communal, to produce goods for both the market and home consumption. The need for policies which strengthen traditional production systems is argued through a detailed case study of Dominica, in the Caribbean. The complexity and diversity of what is often considered a single‐crop (bananas) agricultural system is demonstrated by looking at a number of localities in different parts of the Island. The example of Dominica is used to argue for policies which, in the words of Robert Chambers, (1983), … ‘put the last first’. Such policies should strengthen existing diversity in the agricultural system through initiatives which give local farmers greater control over the planning and implementation of interventions. The sophistication of local technical knowledge is stressed, as is the need to integrate this knowledge with the technical expertise of outside professionals.
Dam construction and the degradation of floodplain forest on the Turkwel River, Kenya
Authors: Adams W. M. 
Published: February 2007

AbstractA hydroelectric dam currently under construction is likely to have significant adverse impacts on riparian forest bordering the Turkwel River in northern Kenya. The forest is dominated by Acacia tortilis which depends upon river flooding. The River has a seasonal and highly ‘flashy’ flow regime, and floods are vital to recharge the floodplain aquifer. Flood regime, bruchid beetle infestation of Acacia pods, and the role of domestic herbivores in killing beetle larvae and grazing seedlings are important influences on Acacia regeneration. The riparian forest is a vital element in the grazing ecology of Turkana pastoralists, particularly in the dry season and in times of drought. Dam construction threatens the degradation of the forest both through reduced survival of existing trees and reduced regeneration. Such degradation would have serious implications for the Turkana.
Spatial and temporal dynamics of land degradation and fluvial erosion in the middle and upper Yangtze River Basin, China
Authors: Hengyue Gu , Douglas Ian 
Published: February 2007

AbstractLand degradation in the middle and upper Yangtze has caused loss of cultivable land, sediment deposition in reservoirs and changes in the runoff: sediment yield relationships of major tributaries. The Jialin River and the Dukou‐Pingshan sector of the Jingsha River together contribute over 75 per cent of all the sediment carried by the Yangtze at Yichang. As the Jialin catchment has the highest rates of erosion per unit area, high sediment discharges from that river exert a major influence on peak summer sediment discharges on the Yangtze. Even though land degradation is increasing in severity, there is no clear overall pattern or trend in variations in sediment yield since 1950. Some tributaries are affected by major reservoir construction and soil conservation works, others are not.
Development of a microbiological treatment for restoration of oil contaminated soil
Authors: Bewley R. J. F. , Ellis B. , Rees J. F. 
Published: February 2007

AbstractThis paper describes the laboratory development of a microbial treatment for soil contaminated with oil hydrocarbon residues at a disused refinery site and the application of this technology in a pilot scale treatment bed in the field.Micro‐organisms isolated from the site capable of utilizing a number of normal and branched chain alkanes were tested in a series of soil microcosms, together with various permutations of commercially available surfactants and nutrients for stimulating the activities of hydrocarbon‐utilizing micro‐organisms. Amongst the most effective reagents were: a the fertiliser ‘PurisolR’ 110(11 per cent N, 11 per cent P205, 11 per cent K20, ‘Chafer, Brit. Ag,’ Ltd.), which in combination with other supplements resulted in reductions of total oil hydrocarbons and associated polar products (TOHP) from 24,100 to below 16,000 mg kg−1 after five weeks (compared to 21,200 mg kg−1 in the control); (b) a hexadecane degrading Acinetobacter sp., which in combination with nutrients, reduced TOHP from 21,400 to 13,200 mg kg−1, in seven weeks compared to 16,800 mg kg−1 in the control and 15,100 mg kg−1 in the treatment with nutrients only and; (c) brewer's yeast which in combination with other supplements reduced TOHP from 16,300 to 7,600 mg kg−1 in 14 weeks.These reagents, together with other supplements were applied to a pilot‐scale treatment bed consisting of 200 m3 of contaminated soil. Reductions in TOHP from 25,500 to 9,400 mg kg−1 were achieved in 15 months. Corresponding reductions in total oil hydrocarbons (TOH) from 22,600 to 2,000 mg kg−1 were achieved in the same period. After this time little further degradation was observed. The requirements for: (a) a critical evaluation of analytical methodology for assessing the bioremediation of oil contaminated soil, and; (b) considering the overall chemical stability of the asphaltene‐like residue remaining after biodegradation of the primary oil has taken place when setting meaningful targets for restoration of oil‐contaminated land, are highlighted in this study.
Reclaiming sandplain seeps by intercepting perched groundwater with eucalypts
Authors: George R. J. 
Published: February 2007

AbstractAt a sandplain seep at East Belka in the Western Australian Wheatbelt, saline groundwater discharge occurs from a shallow (approx. 2 m) perched aquifer of moderate permeability (0.15 m day−1). Groundwater qualities range from over 2,500 mS m−1 in the saline area, to between 660 and 1,700 mS m−1 in the plantation. In 1986 five varieties of eucalypts (E. globulus, E. cladocalyx var. nana and three provenances of E. camaldulensis) were planted across the contour upslope from the seep on about 1.0 per cent of the catchment. By 1989 the seedlings had grown to heights of up to 6.5 m. Despite above‐average rainfall over the study period, perched water‐tables under the plantation and seep were progressively lowered (approx. 0.5‐1.0 m) until the area was dry at the start of the 1989‐1990 summer. Wheat (Triticum aestivum) established on the seep and adjacent paddock in May 1989, provided a yield of over 1.0 t ha−1 on a site that had been unproductive for 20 years.The method has the potential to reclaim much of the existing eastern and northern wheatbelt where there are salinity problems caused by perched groundwater, and could prevent recharge of the regional aquifer beneath the sandplain seep. However, additional techniques will be required to prevent deep aquifer discharge caused by steadily rising (approx. 0.15 m yr−1) regional water‐tables. Discharge and associated dryland salinity from the regional system are expected to be major problems during the next 40 years at the site investigated.
Field evaluation of relationships between a vegetation structural parameter and sheltering against wind erosion
Authors: Musick H. B. , Gillette D. A. 
Published: February 2007

AbstractMeasurements of natural vegetation canopies and of threshold friction velocities for soil movement were made at three arid and semiarid field sites. Threshold friction velocities for the vegetated surface and for bare soil were used to evaluate the partitioning of shear stress between that absorbed by the plant canopies and that absorbed by the soil surface (this potentially causing movement of soil particles). Canopy measurements were used to estimate lateral cover (total frontal‐silhouette area per unit ground area), a parameter shown by previous laboratory studies to be a good predictor of shear stress partitioning. The relationship between lateral cover and shear stress partitioning for the field sites agreed with the laboratory results of Gillette and Stockton (1989). Results indicate that the protective influence of vegetative cover against wind erosion can be successfully predicted using simple measurements of vegetation canopy structure.
Compaction of virgin soil by mechanized agriculture in a semiarid environment
Authors: Holloway R. E. , Dexter A. R. 
Published: February 2007

AbstractSoil compaction was assessed in terms of soil strength as measured with a penetrometer. Penetrometer resistance was measured on virgin soil and on the same soil after one and after five passes of a 7,610 kg tractor. Also, comparative studies were made of strength profiles of soils in arable fields and in adjacent areas of virgin soil. The strength of virgin soil was increased by wheel traffic and agricultural operations in all cases. The increase in soil strength was significant down to 0.3 m, which is considerably greater than the normal depth of tillage in the area (0.05 m). Reduction in the coefficient of variation of penetrometer strengths after the passage of wheels was taken as evidence for associated losses of soil structure. Virgin soils provide important reference sites for assessing the impact of agriculture in an area.
The limits to growth debate and future crisis in Africa: A case‐study from Swaziland
Authors: Proctor J. D. 
Published: February 2007

AbstractAlthough projections of future human and environmental crisis in subSaharan Africa caused by population growth beyond resource limits are common, they are often criticized due to their weak empirical or theoretical basis. This paper attempts to predict whether in 2000 AD there will be adequate cropland, grazing land and fuelwood reserves for a study area located in rural Swaziland. The objective was to establish the likelihood of future crisis, as well as to provide empirical evidence pertinent to the underlying theoretical debate about the relative significance of physical limits to growth. Data used for the study include past and recent aerial photography and census information, plus a field environmental assessment and household survey. Based on this information, projected year 2000 resource constraints for the study area range from minimal (in the case of fuelwood reserves) to extreme (in the case of livestock grazing areas). Other factors, however, such as unequal cropland allocation, household shortages of labour, and privatization of fuelwood supplies, have been found either to exacerbate these constraints or hinder rural resource utilization in the absence of significant physical constraints. A comparison of this study with the United Nations'Potential Population‐Supporting Capacities of Lands in the Developing World(see Higgins,et al., 1983) suggests that the UN projections, based on highly optimistic assumptions and little empirical evidence, are essentially meaningless. Although the results lend some support to the application of the limits to growth scenario to rural Swaziland, the classic ‘overshoot and collapse’ trend associated with that scenario is called into question. The results ultimately suggest that neither the Malthusian emphasis on physical constraints nor the Marxian emphasis on social and political constraints can be dismissed outright in research and policy related to future crisis in subSaharan Africa.