bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nutritional well-being of young children in Duncan Village, East London, South Africa: accessibility of primary health care clinics
Authors: de Villiers Anniza , Koko-Mhlahlo Kholeka , Senekal Marjanne 
Published: September 2005

AbstractObjectiveThe aim was to contribute to the nutritional well-being of young children living in Duncan Village by investigating factors that influence clinic attendance of mothers and to formulate recommendations for optimisation of accessibility of primary health care (PHC) clinics in the area.DesignPHC clinic accessibility was evaluated by assessing the experiences of mothers who attended clinics in the area as well as the experiences of health care workers (HCWs) in these clinics of service delivery and its recipients (mothers/children), using the focus group technique. The ATLAS/ti program was used to analyse the data in the following steps: preparation and importing of the data, getting to know and coding the data, retrieval and examination of codes and quotations, creation of families and creation of networks.SettingDuncan Village, a low socio-economic urban settlement in East London, South Africa.SubjectsFocus group discussions (four to seven participants per group) were conducted with four groups of mothers who do not attend PHC clinics, six with mothers who do attend the clinics (including pregnant women) and four groups of HCWs.ResultsFour networks that provide a summary of all the major trends in the data were created. The results clearly indicate that mothers in Duncan Village perceive and/or experience serious problems that make it difficult for them to attend clinic and even prevent them from doing so. These problems include both the way they are treated at the clinics (especially the problem of verbal abuse) as well as the actual services delivered (no medicines, no help, disorganised, long waiting periods, being turned away). The main problem experienced by the HCWs with service delivery seems to be a heavy workload, as well as the fact that many mothers do not come for follow-up visits.ConclusionEfforts to increase the accessibility of PHC clinics in Duncan Village should focus on improving the relationship between mothers and HCWs and the heavy workload experienced by these workers.
Computation of dynamical correlation functions of Heisenberg chains: the gapless
anisotropic regime
Authors: Caux Jean-Sébastien , Hagemans Rob , Maillet Jean Michel 
Published: September 2005

We compute all dynamical spin–spin correlation functions for the
spin-1/2 XXZ
anisotropic Heisenberg model in the gapless antiferromagnetic regime at zero
temperature, using numerical sums of exact determinant representations for form
factors of spin operators on the lattice. Contributions from intermediate states
containing many particles and string (bound) states are included. We present modified
determinant representations for the form factors valid in the general case with string
solutions to the Bethe equations. Our results are such that the available sum
rules are saturated to high precision. We Fourier transform our results back to
real space, allowing us in particular to make a comparison with known exact
formulae for equal-time correlation functions for small separations in zero field,
and with predictions for the zero-field asymptotics from conformal field theory.
Effect of temperature and moisture on rates of carbon mineralization in a Mediterranean oak forest soil under controlled and field conditions
Authors: Rey A. , Petsikos C. , Jarvis P. G. , Grace J. 
Published: September 2005

SummaryWe examined the relationship between carbon mineralization (Cmin), moisture and temperature in a Mediterranean forest soil under controlled and field conditions. We studied the following.1 The temperature sensitivity at three soil depths: soil samples were incubated at 4, 10, 20 and 30°C at optimal water content of 60% of water holding capacity (WHC). Values ofCminof the top layer were more than 12 times faster than those measured in deeper layers. We found a temperature sensitivity factor (Q10) of 3.3, 2.7 and 2.2 for the 0–5 cm, 5–10 cm and 10–20 cm layers, respectively.2 The relationship betweenCmin, moisture and temperature (top layer). The sensitivity ofCminto fluctuating moisture depended on temperature. However, theQ10was not significantly affected by soil moisture. We fitted a multiple polynomial model that predictedCminas a multiplicative function of temperature and moisture (R2 > 0.99).3 The response ofCminof soil to rewetting after 1 and 24 hours. In all cases, the response was rapid. The soil incubated at 60% WHC or less responded positively to a sudden increase in water content, with the largest increase in the 20% WHC treatment. The model predictedCminin the field well when rewetting effects were taken into account (R2 > 0.81).These results indicate that sudden changes in soil moisture can lead to increased carbon mineralization during the dry summer. It is necessary to include such responses in models as they may represent a substantial loss of carbon in the overall carbon balance of Mediterranean ecosystems.
13C and 15N natural abundances of urban soils and herbaceous vegetation in Karlsruhe, Germany
Authors: Norra S. , Handley L. L. , Berner Z. , Stüben D. 
Published: September 2005

SummaryWe undertook what we believe to be a unique survey of the natural abundances of 13C and 15N in urban soils and plants in Karlsruhe (Germany), a European city of average size. We found broad patterns of these abundances in both soils and plants, which reflected geology and land use. In contrast with studies on smaller areas (showing the direct effect of human activities), our study first determined the extent to which the abundances correlated with land use or underlying geology and then assessed how we could further test such relationships. The spatial pattern of δ13C in surface soil correlated with that of the underlying parent material; construction activities superimposed a secondary signal. Maize cultivation was a source of less negative soil δ13C, whereas the C3 vegetation is a source of more negative soil δ13C. There was a footprint of less negative plant δ13C in the industrial and port areas; plant δ13C downwind of the city was less negative than upwind, which might relate to atmospheric pollution from the port area or to differences in soil properties. There was no significant effect of wind direction or geology on soil or plant δ15N, which was correlated mainly with land use. The largest soil δ15N was under agriculture and the smallest under woodland. The abundance of 15N in inner‐urban soil and plants was intermediate between those of agriculture and forests. This study represents a major advance in the use of stable isotope geochemistry in understanding urban environments.
Long‐term changes in organic matter of woodland soils cleared for arable cropping in Zimbabwe
Authors: Zingore S. , Manyame C. , Nyamugafata P. , Giller K. E. 
Published: September 2005

SummarySubsistence farmers in Africa depend largely on the soil organic matter to sustain crop productivity. Long‐term changes in soil organic carbon and nitrogen were measured after woodland clearance for smallholder subsistence farming or for commercial farming. The contents of organic carbon and nitrogen in soil under reference woodlands were largest (53.3 t C ha−1, 4.88 t N ha−1) in a red clay soil (∼ 50% clay + silt), followed by a granitic sand (∼ 12% clay + silt; 22.8 t C ha−1, 1.47 t N ha−1) and least (19.5 t C ha−1, 0.88 t N ha−1) in a Kalahari sand (∼ 5% clay + silt). Organic carbon declined rapidly under cultivation to attain new equilibria within 10 years on all smallholdings. Greatest losses occurred in soils that initially contained most carbon and nitrogen in the order: red clay (22.4 t C ha−1 and 1.0 t N ha−1) > granitic sand (13.2 t C ha−1 and 0.8 t N ha−1) > Kalahari sand (10.6 t C ha−1 and 0.5 t N ha−1). On the clay soil, commercial farming with intensive use of mineral fertilizers and incorporation of maize stover led to more gradual decline: at equilibrium, contents of carbon and nitrogen were 15 t C ha−1 and 1.7 t N ha−1 greater than on smallholdings with similar soil and climate.In the Kalahari sand the δ13C of organic C remained constant after woodland clearance, and maize contributed less than 10% of the total C even after 55 years. The δ13C signature increased slightly with increasing duration of cultivation by smallholders in the granitic sands and red clay soil where maize contributed 29% and 35% of the C at equilibrium. Under more productive commercial farming, the carbon derived from maize accounted for 50% of the total after 10 years of cultivation and 67% at equilibrium. The persistence of woodland carbon in the sandy soil is attributed to chemical stabilization resulting from large concentrations of lignin and polyphenols in the tree litter, or as charcoal.
An overview of the permanence of soil organic carbon stocks: influence of direct human‐induced, indirect and natural effects
Authors: Smith P. 
Published: September 2005

SummaryIf biospheric sinks, such as soil organic carbon, are to be used to meet obligations for greenhouse gas emission reduction under the Kyoto Protocol, the permanence of these sinks needs to be considered. Further, since only direct human‐induced carbon sinks can be included, and sinks resulting from indirect and natural effects cannot be used, there is a pressing need to separate direct human‐induced effects from indirect and natural effects. Since these effects also influence the permanence of soil organic stocks, this paper attempts to synthesize existing knowledge in soil science, and use models to examine the likely influence of direct, indirect and natural effects on the permanence of soil organic carbon stocks.
Organo‐mineral associations in sandy acid forest soils: importance of specific surface area, iron oxides and micropores
Authors: Eusterhues K. , Rumpel C. , Kögel‐Knabner I. 
Published: September 2005

SummaryOrgano‐mineral associations stabilize soil organic matter, though the mechanisms by which they do so are unclear. We used particle‐size fractions < 6.3 μm of two soils to examine the importance of Fe oxides, short‐range order Al silicates and the surface areas of minerals and micropores on the formation of organo‐mineral associations. In the subsoil Fe oxides were most strongly statistically correlated with the mineral‐bound organic carbon. We therefore assume that they are the most important substrates for the formation of organo‐mineral associations. There is no indication that this is caused by physical protection of organic matter in their micropores (< 2 nm). In the Haplic Podzol, dithionite–citrate–bicarbonate‐soluble short‐range order Al silicates may also play a role. Fe oxide particles were calculated to offer specific surface areas of ∼ 200 m2 g−1 (goethite) and ∼ 800 m2 g−1 (ferrihydrite), corresponding to crystal diameters of only a few nm. We assume that the resulting large amount of oxide‐specific reactive surface sites (conditionally charged hydroxyl groups) is responsible for their dominant role as sorbents. With maximum C loadings of 1.3 mg C per m2 Fe oxide for the Dystric Cambisol and 1.1 mg C per m2 Fe oxide + short‐range order Al silicates for the Haplic Podzol the subsoils of both soils seem to have reached saturation with respect to organic matter sorption. In contrast to subsoil horizons, organo‐mineral associations from topsoils contain much larger amounts of organic matter. Here a larger C loading on Fe oxides or a greater importance of other sorbents in addition to the oxides must be assumed.
Water flow patterns and pesticide fluxes in an upland soil in northern Thailand
Authors: Ciglasch H. , Amelung W. , Totrakool S. , Kaupenjohann M. 
Published: September 2005

SummaryRapid percolation of water through soil facilitates both the recharge and the contamination of groundwater reservoirs. We have studied the variation of water flux and pesticide leaching through a soil in northern Thailand. At a depth of 55 cm, two pits were equipped with tensiometer‐controlled glass suction lysimeters that were connected to a novel on‐line solid‐phase extraction device. Nine insecticides varying in water solubility from 10−2 to 10+6 mg l−1 were applied on the soil surface, and leaching was monitored for 8 weeks. Measured water fluxes were compared with simulated values. Total recovery ranged from traces (malathion, triazophos) to 1.3% (dimethoate) of the applied amount, showing a decreasing retardation with increasing polarity of the substances. All pesticides were detectable in the soil solution during the first rain after application. Due to fingering, 83% of the leachate was transported through 38% of the area at leaching rates of < 2 mm per day. A new adaptation of the Simpson Index revealed that the diversity of the flow pattern increased exponentially with decreasing rates of seepage water flux (R2 = 0.80). No such correlation was found when leaching was faster, indicating that the flow pattern switched from a fingering‐ to a matric‐dominated flux. No long‐term leaching of insecticides was observed. The two profiles studied behaved similarly in terms of both water and pesticide transport. Therefore we suggest that the flow pattern is a stable property of the soil that can be accurately described by our combination of novel experimental setup and statistical analysis of the flow field.
Spatial analysis of categorical soil variables with the wavelet transform
Authors: Lark R. M. 
Published: September 2005

SummaryThis paper describes a wavelet transform for the analysis of categorical (multistate) soil variables, i.e. ones (such as profile classes) that have two or more discrete states. The states are transformed to a continuous variable by a mapping which is optimized by scale and location to highlight local variation.The method is illustrated with data from a transect across a gilgai landscape in Australia. A categorical variable on relief, with three states, was recorded from the sample sites, from which soil cores had also been collected and analysed. The wavelet analysis showed a transient feature of the variation at scales up to 32 m. There was an interval where the characteristic alternation of depressions with the level plain was interrupted. The variation at scale 64 m appeared to be non‐stationary. The relief was more variable on one side of a change point than it was on the other.This complex variation of relief was matched by that of the electrical conductivity of the soil, most strongly at the 64‐m scale. The periodicity of conductivity, and the strength of its correlation with relief, were also different either side of the change point identified in the analysis of relief alone. Conductivity also showed similar transient features to relief.Evidently the wavelet transform can be used to elucidate the variation of categorical soil variables. The information from such an analysis is likely to be useful for planning surveys of the soil to measure continuous variables by sampling and laboratory analysis.
Regulating the mobility of Cd, Cu and Pb in an acid soil with amendments of phosphogypsum, sugar foam, and phosphoric rock
Authors: Garrido F. , Illera V. , Campbell C. G. , García‐González M. T. 
Published: September 2005

SummaryWhen acid soil has been contaminated by metals as a result of industrial discharges, accidental spills, or acid mine drainage it may be desirable to retain the metals in the soil rather than allow them to leach away. We have investigated the potential of phosphogypsum (PG), sugar foam (SF), and phosphoric rock (PR) to regulate the availability and mobility of Pb, Cd and Cu. We have also identified changes in attenuation during incubation for 1 year and the effect of aging on metal speciation in amended soils. We studied miscible displacement in columns of undisturbed soil previously treated with solutions of the amendments and soluble metals and, subsequently, single and sequential chemical metal extractions. All amendments increased the soil's metal retention capacity. This, in turn, increased the amount of metal extractable by diethylenetriaminepentaacetic acid (DTPA). However, over time the amounts of DTPA‐extractable metal decreased, particularly for Cu and Pb. Both Cu and Cd were held preferentially within the acetic acid‐extractable fraction (operationally defined exchangeable fraction – EX fraction), whereas Pb was associated mainly with the hydroxylammonium‐extractable fraction (operationally defined bound to Fe and Al hydroxides – OX fraction). Both Pb and Cu in the oxide and organic fractions increased in the PG‐ and SF‐treated soils. In general, the distribution of metal did not change in the PR‐treated columns after the incubation. Finally, scanning electron microscopy in back‐scattered electron mode (SEM–BSE) showed the formation of Al‐hydroxy polymers which provides the soils with additional cation sorption capacity. In the PG‐ and PR‐treated columns, P and S were associated with these formations. The three metals were associated with the Al polymers, probably through direct coordination or the formation of ternary complexes with the inorganic ligands phosphate and sulphate.
Soil sorption–desorption of phosphorus from piggery effluent compared with inorganic sources
Authors: Redding M. R. , Shatte T. , Bell K. 
Published: September 2005

SummaryThe leaching of phosphorus (P) within soils can be a limiting consideration for the sustainable operation of intensive livestock enterprises. Sorption curves are widely used to assist estimation of P retention, though the effect of effluent constituents on their accuracy is not well understood. We conducted a series of P‐sorption–desorption batch experiments with an Oxic Haplustalf (soil 1), Haplusterts (soils 2 and 3), and a Natrustalf (soil 4). Phosphorus sources included effluent, orthophosphate‐P in a matrix replicating the effluent's salt constituents (the reference solution), and an orthophosphate‐P solution. Treated soils were incubated for up to 193 days before sequential desorption extraction. Effluent constituents, probably the organic or particulate components, temporarily increased the vulnerability of sorbed‐P to desorption. The increase in vulnerability was removed by 2–113 days of incubation (25°C). Despite vigorous extraction for 20 consecutive days, some P sorbed as part of the treatments of soils 1 and 2 was not desorbed. The increased vulnerability due to effluent constituents lasted a maximum of about one cropping season and, for all other treatments, adsorption curves overestimated vulnerability to desorption. Therefore, adsorption curves provide a conservative estimate of vulnerability to desorption where effluent is used in continued crop production in these soils.
Organic carbon stocks in the Russian Chernozem
Authors: Mikhailova E. A. , Post C. J. 
Published: September 2005

SummaryChernozems (Mollisols) play an important role in the global carbon cycle, but their contribution to the global carbon stock is often underestimated. We have estimated stocks of organic carbon in the upper 2 m in the Russian Chernozem (Haplic Chernozem) under four management regimes: a native grassland (not cultivated for at least 300 years), an adjacent continuous fallow field, a yearly‐cut meadow and an arable field in the Kursk region of Russia. The organic carbon stored in the top 2 m was 462 t ha−1 for the grassland, 451 t ha−1 for the yearly‐cut meadow, 387 t ha−1 for the arable field and 349 t ha−1 for the continuous fallow. From 18 to 26% of the total organic C in the top 2 m was between 1 and 2 m in all four regimes. Vertical distribution of organic C was modelled by an exponential function for which the R2 values lay in the range 0.89–0.95, depending on the regime. This exponential function was used to predict organic C below 2 m in the Haplic Chernozem. Model estimates showed that if we include organic C stored in the Russian Chernozem between 1 and 3 m we shall increase our estimates of C stored by 27–30%.
Sources of nitrite in a permanent grassland soil
Authors: Müller C. , Stevens R. J. , Laughlin R. J. 
Published: September 2005

SummaryThe objective of this study was to separate the observed nitrite (NO2–) concentration in a permanent grassland soil into process‐specific subpools. A laboratory experiment was carried out where either the nitrate and/or ammonium pool was labelled with 15N at 60 atom % excess. The main N transformations that occurred in this experiment were analysed with a 15N tracing model extended with a NO2– submodel. Techniques that have been used to date have been only able to identify NO2– subpools related to nitrification (NO2–nit) and denitrification (NO2–den). With the analysis presented here, we were able to quantify the size of an additional NO2– pool in the soil related to organic N turnover (NO2–org). All transformations related to NO2– turnover of the three subpools occurred simultaneously. After non‐linear parameter optimization the model predicted that on average NO2–den, NO2–nit and NO2–org pools contributed 57, 33 and 10% to the total soil NO2– concentration. The finding that heterotrophic processes can contribute to the NO2– dynamics in permanent grassland soils might also have important implications for the understanding of gaseous N production that are tightly linked to NO2– turnover. Further work is needed to find out how important the conversion of organic N to NO2– is in other soil‐based ecosystems and to identify the microbial groups responsible for this process.
Methane and nitrous oxide fluxes of soils in pure and mixed stands of European beech and Norway spruce
Authors: Borken W. , Beese F. 
Published: September 2005

SummaryTree species can affect the sink and source strength of soils for atmospheric methane and nitrous oxide. Here we report soil methane (CH4) and nitrous oxide (N2O) fluxes of adjacent pure and mixed stands of beech and spruce at Solling, Germany. Mean CH4 uptake rates ranged between 18 and 48 μg C m−2 hour−1 during 2.5 years and were about twice as great in both mixed and the pure beech stand as in the pure spruce stand. CH4 uptake was negatively correlated with the dry mass of the O horizon, suggesting that this diminishes the transport of atmospheric CH4 into the mineral soil. Mean N2O emission was rather small, ranging between 6 and 16 μg N m−2 hour−1 in all stands. Forest type had a significant effect on N2O emission only in one mixed stand during the growing season. We removed the O horizon in additional plots to study its effect on gas fluxes over 1.5 years, but N2O emissions were not altered by this treatment. Surprisingly, CH4 uptake decreased in both mixed and the pure beech stands following the removal of the O horizon. The decrease in CH4 uptake coincided with an increase in the soil moisture content of the mineral soil. Hence, O horizons may maintain the gas diffusivity within the mineral soil by storing water which cannot penetrate into the mineral soil after rainfall. Our results indicate that conversion of beech forests to beech–spruce and pure spruce forests could decrease soil CH4 uptake, while the long‐term effect on N2O emissions is expected to be rather small.