bluuebunny/crossref_metadata_2025 huggingface dataset:
Fortification of maize meal improved the nutritional status of 1–3-year-old African children
Authors: Nesamvuni Alufheli E , Vorster Hester H , Margetts Barrie M , Kruger Annamarie
Published: September 2005

Objective

To evaluate the effectiveness of a vitamin-fortified maize meal to improve the nutritional status of 1–3-year-old malnourished African children.

Design

A randomised parallel intervention study was used in which 21 experimental children and their families received maize meal fortified with vitamin A, thiamine, riboflavin and pyridoxine, while 23 control children and their families received unfortified maize meal. The maize meal was provided for 12 months to replace the maize meal habitually consumed by these households.

Methods

Sixty undernourished African children with height-for-age or weight-for-age below the 5th percentile of the National Center for Health Statistics' criteria and aged 1–3 years were randomly assigned to an experimental or control group. Baseline measurements included demographic, socio-economic and dietary data, as well as height, weight, haemoglobin, haematocrit, serum retinol and retinol-binding protein (RBP). Anthropometric, blood and serum variables were measured again after 12 months of intervention. Complete baseline measurements were available for 44 children and end data for only 36. Changes in these variables from baseline to end within and between groups were assessed for significance with paired t-tests, t-tests and analysis of variances using the SPSS program, controlling for expected weight gain in this age group over 12 months. Relationships between changes in variables were examined by calculating correlation coefficients.

Results

The children in the experimental group had a significantly (P≤0.05) higher increase in body weight than control children (4.6 kg vs. 2.0 kg) and both groups had significant (P≤0.05) but similar increases in height. The children in the experimental group showed non-significant increases in haemoglobin and serum retinol, while the control children had a significant (P = 0.007) decrease in RBP. The change in serum retinol showed a significant correlation with baseline retinol (P = 0.014), RBP (P = 0.007) and weight (P = 0.029), as well as with changes in haemoglobin (P = 0.029).

Conclusion

Despite a small sample size, this study showed positive effects of a vitamin-fortified maize meal on weight gain and some variables of vitamin A status in 1–3-year-old African children. The study confirmed the relationship between vitamin A and iron status. The results suggest that fortification of maize meal would be an effective strategy to address micronutrient deficiencies in small children in South Africa.
Development and validation of instruments measuring body image and body weight dissatisfaction in South African mothers and their daughters
Authors: Mciza Zandile , Goedecke Julia H , Steyn Nelia P , Charlton Karen , Puoane Thandi , Meltzer Shelly , Levitt Naomi S , Lambert Estelle V
Published: September 2005

Objective

We sought to validate questionnaires concerning body image perception, body size dissatisfaction and weight-related beliefs in multi-ethnic South African mothers and their daughters.

Settings and subjects: Girls attending primary school (ages 9–12 years, n = 333) and their mothers (n = 204) were interviewed regarding their demographics and body image. Weight, height and skinfold thicknesses were measured. Body image questions and body mass index (BMI) were compared with silhouettes adapted from the Pathways Study for girls and Stunkard's body image figures for mothers. A Feel–Ideal Difference (FID) index score was created by subtracting the score of the silhouette selected by the participants as ‘Ideal’ from the one selected as most closely representing their current appearance or ‘Feel’. We hypothesised that a higher FID index score would be associated with greater body size dissatisfaction.

Results

BMI percentiles in girls (r = 0.46, P < 0.05) and BMI in mothers (r = 0.68, P < 0.05) were positively correlated with the selected silhouettes based on size. Participants who reported feelings of being ‘fat’ and those who perceived that their family and friends were more dissatisfied with their body size had significantly higher FID index scores. Scores were lower in black than white girls (all P < 0.05). No differences were found in FID index scores between ethnic groups of mothers. Internal reliability of the ‘thin’ and ‘fat’ belief constructs for girls was demonstrated by standardised Cronbach's α values ≥0.7.

Conclusion

Silhouettes, FID index, ‘fat’ and ‘thin’ belief constructs (in girls) are age-appropriate, culturally sensitive and can be used in further intervention studies to understand body image.
The National Food Consumption Survey (NFCS): South Africa, 1999
Authors: Labadarios D , Steyn NP , Maunder E , MacIntryre U , Gericke G , Swart R , Huskisson J , Dannhauser A , Vorster HH , Nesmvuni AE , Nel JH
Published: September 2005

Objective

The aim of the National Food Consumption Survey (NFCS) in South Africa was to determine the nutrient intakes and anthropometric status of children (1–9 years old), as well as factors that influence their dietary intake.

Design

This was a cross-sectional survey of a nationally representative sample of all children aged 1–9 years in South Africa. A nationally representative sample with provincial representation was selected using 1996 Census information.

Subjects

Of the 3120 children who were originally sampled data were obtained from 2894, a response rate of 93%.

Methods

The sociodemographic status of each household was assessed by a questionnaire. Dietary intake was assessed by means of a 24-hour recall and a food-frequency questionnaire from the caregivers of the children. Food purchasing practices were determined by means of a food procurement questionnaire. Hunger was assessed by a modified hunger scale questionnaire. Nutritional status was determined by means of anthropometric measurements: height, weight, head circumference and arm circumference.

Results

At the national level, stunting (height-for-age below minus two standard deviations (< -2SD) from the reference median) was by far the most common nutritional disorder, affecting nearly one in five children. The children least affected (17%) were those living in urban areas. Even with regard to the latter, however, children living in informal urban areas were more severely affected (20%) compared with those living in formal urban areas (16%). A similar pattern emerged for the prevalence of underweight (weight-for-age < -2SD), with one in 10 children being affected at the national level. Furthermore, one in 10 (13%) and one in four (26%) children aged 1–3 years had an energy intake less than half and less than two-thirds of their daily energy needs, respectively. For South African children as a whole, the intakes of energy, calcium, iron, zinc, selenium, vitamins A, D, C and E, riboflavin, niacin, vitamin B6 and folic acid were below two-thirds of the Recommended Dietary Allowances. At the national level, data from the 24-hour recalls indicated that the most commonly consumed food items were maize, sugar, tea, whole milk and brown bread. For South African children overall, one in two households (52%) experienced hunger, one in four (23%) were at risk of hunger and only one in four households (25%) appeared food-secure.

Conclusion

The NFCS indicated that a large majority of households were food-insecure and that energy deficit and micronutrient deficiencies were common, resulting in a high prevalence of stunting. These results were used as motivation for the introduction of mandatory fortification in South Africa.
FOXO1a acts as a selective tumor suppressor in alveolar rhabdomyosarcoma
Authors: Bois Philippe R.J. , Izeradjene Kamel , Houghton Peter J. , Cleveland John L. , Houghton Janet A. , Grosveld Gerard C.
Published: September 2005

Rhabdomyosarcoma (RMS), the most common pediatric soft-tissue sarcoma, has two major histological subtypes: embryonal RMS (ERMS), which has a favorable prognosis, and alveolar RMS (ARMS), which has a poor outcome. Although both forms of RMS express muscle cell–specific markers, only ARMS cells express PAX3-FOXO1a or PAX7-FOXO1a chimeric proteins. In mice, Pax3 and Pax7 play key roles in muscle cell development and differentiation, and FoxO1a regulates myoblast differentiation and fusion; thus, the aberrant regulation of these proteins may contribute to the development of ARMS. In this paper, we report that FOXO1a is not expressed in primary ARMS tumors or ARMS-derived tumor cell lines and that restoration of FOXO1a expression in ARMS cells is sufficient to induce cell cycle arrest and apoptosis. Strikingly, the effects of FOXO1a are selective, as enforced expression of FOXO1a in ERMS-derived tumor cell lines had no effect. Furthermore, FOXO1a induced apoptosis in ARMS by directly activating the transcription of caspase-3. We conclude that FOXO1a is a potent and specific tumor suppressor in ARMS, suggesting that agents that restore or augment FOXO1a activity may be effective as ARMS therapeutics.
Dynamic cycling of eIF2 through a large eIF2B-containing cytoplasmic body
Authors: Campbell Susan G. , Hoyle Nathaniel P. , Ashe Mark P.
Published: September 2005

The eukaryotic translation initiation factor 2B (eIF2B) provides a fundamental controlled point in the pathway of protein synthesis. eIF2B is the heteropentameric guanine nucleotide exchange factor that converts eIF2, from an inactive guanosine diphosphate–bound complex to eIF2-guanosine triphosphate. This reaction is controlled in response to a variety of cellular stresses to allow the rapid reprogramming of cellular gene expression. Here we demonstrate that in contrast to other translation initiation factors, eIF2B and eIF2 colocalize to a specific cytoplasmic locus. The dynamic nature of this locus is revealed through fluorescence recovery after photobleaching analysis. Indeed eIF2 shuttles into these foci whereas eIF2B remains largely resident. Three different strategies to decrease the guanine nucleotide exchange function of eIF2B all inhibit eIF2 shuttling into the foci. These results implicate a defined cytoplasmic center of eIF2B in the exchange of guanine nucleotides on the eIF2 translation initiation factor. A focused core of eIF2B guanine nucleotide exchange might allow either greater activity or control of this elementary conserved step in the translation pathway.
A novel mechanism of actin filament processive capping by formin
Authors: Shemesh Tom , Otomo Takanori , Rosen Michael K. , Bershadsky Alexander D. , Kozlov Michael M.
Published: September 2005

The FH2 domains of formin family proteins act as processive cappers of actin filaments. Previously suggested stair-stepping mechanisms of processive capping imply that a formin cap rotates persistently in one direction with respect to the filament. This challenges the formin-mediated mechanism of intracellular cable formation. We suggest a novel scenario of processive capping that is driven by developing and relaxing torsion elastic stresses. Based on the recently discovered crystal structure of an FH2–actin complex, we propose a second mode of processive capping—the screw mode. Within the screw mode, the formin dimer rotates with respect to the actin filament in the direction opposite to that generated by the stair-stepping mode so that a combination of the two modes prevents persistent torsion strain accumulation. We determine an optimal regime of processive capping, whose essence is a periodic switch between the stair-stepping and screw modes. In this regime, elastic energy does not exceed feasible values, and supercoiling of actin filaments is prevented.
Proline residues of transmembrane domains determine the sorting of inner membrane proteins in mitochondria
Authors: Meier Stephan , Neupert Walter , Herrmann Johannes M.
Published: September 2005

Most inner membrane proteins of mitochondria are synthesized in the cytosol and reach the inner membrane using one of two alternative sorting pathways. On the stop transfer route, proteins are arrested during import at the level of the inner membrane. The conservative sorting pathway involves translocation through the inner membrane and insertion from the matrix. It is unclear how the translocase of the inner membrane 23 protein translocation machinery differentiates between the two classes of proteins. Here we show that proline residues in hydrophobic stretches strongly disfavor the translocation arrest of transmembrane domains (TMDs) and favor the transfer of preproteins to the matrix. We propose that proline residues, together with the hydrophobicity of the TMD and the presence of charged residues COOH-terminally flanking the TMD, are determinants of the intramitochondrial sorting of inner membrane proteins.
Syntabulin-mediated anterograde transport of mitochondria along neuronal processes
Authors: Cai Qian , Gerwin Claudia , Sheng Zu-Hang
Published: September 2005

In neurons, proper distribution of mitochondria in axons and at synapses is critical for neurotransmission, synaptic plasticity, and axonal outgrowth. However, mechanisms underlying mitochondrial trafficking throughout the long neuronal processes have remained elusive. Here, we report that syntabulin plays a critical role in mitochondrial trafficking in neurons. Syntabulin is a peripheral membrane-associated protein that targets to mitochondria through its carboxyl-terminal tail. Using real-time imaging in living cultured neurons, we demonstrate that a significant fraction of syntabulin colocalizes and co-migrates with mitochondria along neuronal processes. Knockdown of syntabulin expression with targeted small interfering RNA or interference with the syntabulin–kinesin-1 heavy chain interaction reduces mitochondrial density within axonal processes by impairing anterograde movement of mitochondria. These findings collectively suggest that syntabulin acts as a linker molecule that is capable of attaching mitochondrial organelles to the microtubule-based motor kinesin-1, and in turn, contributes to anterograde trafficking of mitochondria to neuronal processes.
Detection of contact hypersensitivity to corticosteroids in allergic contact dermatitis patients who do not respond to topical corticosteroids
Authors: Gönül Müzeyyen , Gül Ülker
Published: September 2005

The delayed hypersensitivity development against topical corticosteroids which are used in allergic contact dermatitis (ACD) treatment is an important clinical problem. In our study, 41 ACD patients who did not show any response to topical corticosteroid treatment were patch tested with corticosteroid series and the commercial preparations of corticosteroids and their vehicles. In corticosteroid series, there were budesonide, bethametasone‐17‐valerate, triamcinolone acetonide, tixocortol pivalate, alclomethasone‐17‐21‐dipropionate, clobetasole‐17‐propionate, dexamethasone‐21‐phosphate disodium and hydrocortisone‐17‐butyrate. We detected positive reaction to corticosteroids in 9 of our cases (22%) (5 single and 4 multiple). The sensitivity was mostly produced by tixocortol pivalate (6 patients). This was followed by triamcinolone acetonide (2 patients) budesonide (2 patients), alclomethasone dipropionate (2 patients), dexamethasone 21 phosphate disodium (2 patients) and betamethasone‐17‐valerate (1 patient). As a result, it should not be forgotten that the corticosteroids used to treat ACD patients may cause ACD themselves. In ACD patients who did not respond to corticosteroid treatment, routinely applying patch test with corticosteroids should be helpful in directing the treatment.
Patch testing with p‐toluene diamine preparations of different ages*†
Authors: Geier Johannes , Lessmann Holger , Schnuch Axel , Hildebrandt Stephan , Uter Wolfgang
Published: September 2005

Analyses of the stability of 1% p‐toluene diamine (PTD) in petrolatum used for patch testing showed a rapid decline of the PTD concentration down to 0.1%, possibly due to the generation of dye complexes. To study whether the diagnostic quality of this test preparation is compromised by the chemical reactions taken place, a multicentre study was conducted by the German Contact Dermatitis Research Group (DKG), comparing patch test results in 177 patients with simultaneously tested PTD preparations of different ages. During the 10‐month course of this study, the age of the batches ranged from 2 to 11 months for batch A, from 7 to 16 months for batch B and from 11 to 20 months for batch C. There were no statistically significant differences between reactions to batches A and B, A and C, and B and C. Agreement of patch test reactions to the 3 batches was very good and comparable to the general reproducibility of patch test with standard allergens. The chemical reactions mentioned above apparently do not affect the diagnostic quality of PTD patch test preparations because the true allergen probably is not PTD itself, but one or more of the reaction products.
Gold trichloride and gold sodium thiosulfate as markers of contact allergy to gold
Authors: Möller Halvor , Ahnlide Ingela , Gruvberger Birgitta , Bruze Magnus
Published: September 2005

The usefulness of a trivalent gold salt, gold trichloride (GTC), was evaluated as a marker of contact allergy to gold. Patients patch test‐positive or patch test‐negative to gold sodium thiosulfate (GSTS), 13 subjects of each, were patch tested with dilution series of GTC and equimolar concentrations of GSTS. In order to avoid false‐positive and false‐negative test reactions, the salts were buffered and placed on polypropene chambers. Allergic reactions were registered in 9/13 gold‐allergic patients with GSTS and in 2/13 with GTC. The sum of positive reactions was 18 with GSTS and 5 with GTC. Irritant reactions were none with GSTS and 2 with GTC in the gold‐allergic patients. It is concluded that GTC can elicit positive patch test reactions in patients with gold allergy but to a lesser degree when compared with GSTS. Thus, GTC cannot be recommended in patch testing, and GSTS is still the test agent of choice.
The complex problem of sensitive skin
Authors: Marriott Marie , Holmes Jo , Peters Lisa , Cooper Karen , Rowson Matthew , Basketter David A.
Published: September 2005

There exists within the population subsets of individuals who display heightened skin reactivity to materials the majority find tolerable. In a series of investigations, we have examined interrelationships between many of the endpoints associated with the term ‘sensitive skin’. In the most recent work, 58 volunteers were treated with 10% lactic acid, 50% ethanol, 0.5% menthol and 1.0% capsaicin on the nasolabial fold, unoccluded, with sensory reactions recorded at 2.5 min, 5 min and 8 min after application. Urticant susceptibility was evaluated with 1 m benzoic acid and 125 mM trans‐cinnamic acid applied to the volar forearm for 20 min. A 2 × 23‐h patch test was also conducted using 0.1% and 0.3% sodium dodecyl sulfate, 0.3% and 0.6% cocamidopropyl betaine and 0.1% and 0.2% benzalkonium chloride to determine irritant susceptibility. As found in previous studies, increased susceptibility to one endpoint was not predictive of sensitivity to another. In our experience, nasolabial stinging was a poor predictor of general skin sensitivity. Nevertheless, it may be possible to identify in the normal population individuals who, coincidentally, are more generally sensitive to a range of non‐immunologic adverse skin reactions. Whether such individuals are those who experience problems with skin care products remains to be addressed.
Survey of sulfur‐containing rubber accelerator levels in latex and nitrile exam gloves
Authors: Depree G. J. , Bledsoe T. A. , Siegel P. D.
Published: September 2005

2‐Mercaptobenzothiazole and zinc dialkyldithiocarbamates are commonly used sulfur‐containing rubber vulcanization accelerators known to cause allergic contact dermatitis. Exposure to these agents occurs through clothing such as undergarments and shoes, latex medical devices and latex and nitrile gloves. A simple, inexpensive screening method for total sulfur accelerator and a high performance liquid chromatographic speciation method were developed in the present study. These methods were applied to screen and quantify the sulfur accelerator content from 38 brands of ‘off‐the‐shelf’ latex and nitrile gloves obtained from commercial vendors. It was found that accelerator levels ranged from not detectable to 7.35 mg/g in the gloves analysed. Brands were found to contain single and multiple accelerator species within the glove. Powdered gloves had significantly higher accelerator levels than powder‐free gloves from the same manufacturer; however, these chemical accelerators do not preferentially partition to the powder. The present analytical methodology is suitable for both manufacturing quality validation purposes, as well as for accelerator allergy research.
Mapping of quantitative trait loci for carcass traits in a Japanese Black (Wagyu) cattle population
Authors: Mizoguchi Y. , Watanabe T. , Fujinaka K. , Iwamoto E. , Sugimoto Y.
Published: September 2005

To detect quantitative trait loci (QTL) that influence economically important traits in a purebred Japanese Black cattle population, we performed a preliminary genome‐wide scan using 187 microsatellite markers across a paternal half‐sib family composed of 258 offspring. We located six QTL at the 1% chromosome‐wise level on bovine chromosomes (BTA) 4, 6, 13, 14 and 21. A second screen of these six QTL regions using 138 additional paternal offspring half‐sib from the same sire, provided further support for five QTL: carcass weight on BTA14 (22–39 cM), one for rib thickness on BTA6 (27–58 cM) and three for beef marbling score (BMS) on BTA4 (59–67 cM), BTA6 (68–89 cM) and BTA21 (75–84 cM). The location of QTL for subcutaneous fat thickness on BTA13 was not supported by the second screen (P > 0.05). We determined that the combined contribution of the three QTLs for BMS was 10.1% of the total variance. The combined phenotypic average of these three Q was significantly different (P < 0.001) from those of other allele combinations. Analysis of additional half‐sib families will be necessary to confirm these QTL.
An integrated radiation hybrid map of bovine chromosome 18 that refines a critical region associated with multiple ocular defects in cattle
Authors: Abbasi A. R. , Geriletoya  , Ihara N. , Khalaj M. , Sugimoto Y. , Kunieda T.
Published: September 2005

Congenital multiple ocular defects (MOD) of Japanese black cattle is a hereditary ocular disorder with an autosomal recessive mode of inheritance showing developmental defects of the lens, retina and iris, persistent embryonic eye vascularization and microphthalmia. The MOD locus has been mapped by linkage analysis to a 6.6‐cM interval on the proximal end of bovine chromosome 18, which corresponds to human chromosome 16q and mouse chromosome 8. To refine the MOD region in cattle, we constructed an integrated radiation hybrid (RH) map of the proximal region of bovine chromosome 18, which consisted of 17 genes and 10 microsatellite markers, using the SUNbRH7000 panel. Strong conservation of gene order was found among the corresponding chromosomal regions in cattle, human and mouse. The MOD‐critical region was fine mapped to a 59.5‐cR region that corresponds to a 6.3‐Mb segment of human chromosome 16 and a 4.8‐Mb segment of mouse chromosome 8. Several positional candidate genes, including FOXC2 and USP10, were identified in this region.
An effect of a missense mutation in the porcine melanocortin‐4 receptor (MC4R) gene on production traits in Polish pig breeds is doubtful
Authors: Stachowiak M. , Szydlowski M. , Obarzanek‐Fojt M. , Switonski M.
Published: September 2005

A missense G–A SNP in the porcine melanocortin‐4 receptor (MC4R) gene that causes an Asp–Asn substitution at position 298 of the corresponding MC4R protein is considered to be economically important, although published results on its effect are inconsistent. We analysed the association of this MC4R polymorphism with production traits in 679 gilts from two breeds, Polish Large White (PLW) and Polish Landrace (PL), as well as one synthetic line 990. The frequency of the A allele differed significantly among the breeds with frequencies of 0.76, 0.29 and 0.16 in PLW, PL and line 990 respectively. There was no evidence of an effect of this polymorphism on daily food intake, backfat thickness or abdominal fat. The A allele was correlated with higher test daily gains and lower levels of intramuscular fat in PL, and increased levels of intramuscular fat in PLW.
Mineralogical control of organic carbon dynamics in a volcanic ash soil on La Réunion
Authors: Basile‐Doelsch I. , Amundson R. , Stone W. E. E. , Masiello C. A. , Bottero J. Y. , Colin F. , Masin F. , Borschneck D. , Meunier J. D.
Published: September 2005

In soil carbon dynamics, the role of physicochemical interactions between organic matter and minerals is not well understood nor quantified. This paper examines the interactions between soil organic matter and poorly crystalline aluminosilicates in a volcanic ash soil on La Réunion in the southern tropics. The soil examined is a profile composed of a surface soil (L‐Ao‐E‐Bh) overlying four buried horizons (horizons 2Bw, 3Bw, 4Bw, 5Bw) that have all developed from successive tephra deposits. Non‐destructive spectroscopy (XRD, FTIR and NMR of Si and Al) showed that the mineralogical composition varies from one buried horizon to another. Further, we show that buried horizons characterized by large amounts of crystalline minerals (feldspars, gibbsite) have the least capacity to store organic matter and the fastest carbon turnover. In contrast, buried horizons containing much poorly crystalline material (proto‐imogolite and proto‐imogolite allophane, denoted LP‐ITM) store large amounts of organic matter which turns over very slowly. To understand the mechanism of interactions between LP‐ITM and organic matter better, we focused on a horizon formed exclusively of LP‐ITM. We demonstrate, using Δ14C and δ13C values, that even though LP‐ITM is extraordinarily effective at stabilizing organic matter, C linked to LP‐ITM is still in dynamic equilibrium with its environment and cycles slowly. Based on Δ14C values, we estimated the residence time of organic C as ∼ 163 000 years for the most stabilized subhorizon, a value that is comparable to that for organic carbon stabilized in Hawaiian volcanic soils. However, this calculation is likely to be biased by the presence of microcharcoal. We characterized the organo‐mineral binding between organic matter and LP‐ITM by 27Al NMR, and found that the organic matter is not only chelated to LP‐ITM, but it may also limit the polymerization of mineral phases to a stage between proto‐imogolite and proto‐imogolite allophane. Our results demonstrate the important role of poorly crystalline minerals in the storage of organic C, and show that mineral and organic compounds have to be studied simultaneously to understand the dynamics of organic C in the soil.
Modelling the effect of water distribution and hysteresis on air‐filled pore space
Authors: Horgan G. W. , Ball B. C.
Published: September 2005

Soil pore networks have a complex geometry, which is challenging to model in three dimensions. We use a Boolean model of pore space that has proved useful in modelling gas diffusion in dry structures to investigate the distribution of water in this pore space and to quantify the effects on pore connectivity to the soil surface. We first show how total porosity in dry soil influences connectivity via the percolation threshold. Then we show that our model simulation of the ‘ink‐bottle effect’ can account for much of the hysteresis of the soil water. The differences in distribution of water between wetting and drying result in maintaining greater connectivity of the air‐filled pore space during drying than during wetting. Hysteresis is large at small total porosities and slowly declines as porosity increases. During wetting much pore space is blocked when more than 40% of the pore space is filled with water, although during drying all non‐isolated air‐filled pores are connected to the surface. Even when soil is allowed to wet to near saturation, there are rapid increases in pore connectivity during drying, which may explain, for example, rapid increases in production and emission of nitrous oxide in soils near saturation.
Determination of effective release rates of polycyclic aromatic hydrocarbons and dissolved organic carbon by column outflow experiments
Authors: Wehrer M. , Totsche K. U.
Published: September 2005

Risk assessment of groundwater pollution requires quantitative information on the release kinetics of pollutants and organic matter from contaminated soil. We applied a new experimental design for column outflow experiments to investigate the release of polycyclic aromatic hydrocarbons (PAHs) and dissolved organic matter under water‐saturated flow conditions. We used materials originating from a soil contaminated with non‐aqueous phase liquids. To distinguish between release at equilibrium and release limited by mass transfer, we used two flow velocities and multiple interruptions to the flow. We quantified release and transport parameters by inverse numerical simulation of the individual breakthrough curves, applying a model based on the advection–dispersion equation including non‐equilibrium and non‐linear sorption. Release of the dissolved organic C takes place in two steps. Initially, a large amount of readily available organic matter is released. This first flush is followed by an outflow with typical characteristics of rate‐limited release: larger concentrations in slower flow and increased concentrations after interruptions. The breakthrough of PAHs responds neither to the different flow velocities nor to the interruptions. We hypothesize that release of PAHs from the contaminated material is governed by dissolution at equilibrium according to Raoult's law. The boundary conditions of the experimental design, i.e. the flow velocities and multiple interruptions, enable us to distinguish between release at equilibrium and that which is rate‐limited. Also, the response of the breakthrough behaviour to the boundary conditions can be used to estimate inversely effective release parameters.
Adjusted Fick's law for gas diffusion in soils contaminated with petroleum hydrocarbons
Authors: Van De Steene J. , Verplancke H.
Published: September 2005

In bioremediation, hydrocarbon biodegradation rates can be estimated from measured O2 and CO2 profiles in situ. Although Fick's law is typically used in calculating the respiration rates, its theoretical base is weak. We propose an adjusted Fick's law with a correction term for the advective flux. We evaluated the applicability of this model to simulate gas diffusion associated with passive degradation of petroleum hydrocarbons in a biopile by comparing the results of this model with the results of Fick's law and the Stefan–Maxwell equations. The deviations from the use of Fick's law depended strongly on the consumption rate of oxygen, the respiration quotient, the mineralization quotient and the volatility of the hydrocarbon. In the whole range of calculated CO2 concentration versus depth profiles, production rates of CO2 could be estimated by Fick's law with a maximum deviation of 6%. For the consumption rate of O2 the maximum deviation is 19%. However, when we used the adjusted Fick's law, the deviations from the results obtained with the Stefan–Maxwell equations were much smaller. The deviations amounted up to only 4%, when the respiration rate r was 1.5 or a hydrocarbon with volatility similar to benzene was present. If the presence of a hydrocarbon was neglected in the calculations, the deviations of the adjusted Fick's law from the results obtained with the Stefan–Maxwell equations were substantial for a hydrocarbon with volatility similar to benzene or toluene.
Mobility of Cd and Zn in polluted and unpolluted Spodosols
Authors: Degryse F. , Smolders E.
Published: September 2005

Leaching of Cd and Zn in polluted acid, well‐drained soils is a critical pathway for groundwater pollution. Models predicting future groundwater contamination with these metals have rarely been validated at the field scale. Spodosol profiles (pH 3.2–4.5) were sampled in an unpolluted (reference) field and in a field contaminated with Cd and Zn through atmospheric deposition near a zinc smelter. Average metal concentrations in the upper horizons were 0.2 mg Cd kg−1 and 9 mg Zn kg−1 in the unpolluted field, and 0.8 mg Cd kg−1 and 71 mg Zn kg−1 in the contaminated field. Isotopic dilution was used to measure the labile concentration of Cd and Zn, and the metal transport was modelled using measured sorption parameters that describe the distribution between the labile metal pool (instead of the total metal pool) and the solution phase obtained by centrifugation. Solutions were also collected by wick samplers in two polluted and one unpolluted profile at a depth of 70 cm. Concentrations in these solutions were in the order of 15 µg Cd litre−1 and 0.8 mg Zn litre−1 for the polluted profiles, and 1 µg Cd litre−1 and 0.04 mg Zn litre−1 for the unpolluted profile. The concentrations in these solutions agreed well with those in soil solutions obtained by centrifugation, which supported the use of the local equilibrium assumption (LEA). Present‐day Cd profiles in the polluted field were calculated with the LEA, based on the emission history of the nearby smelter and taking spatial variability into account. Observed and predicted depth profiles agreed reasonably well, but total Cd concentrations in the topsoil were generally underestimated by the model. This may be attributed to the presence of non‐labile Cd in the atmospheric deposition, which was not accounted for in the retrospective modelling. The large concentrations of non‐labile Zn in the topsoil of the polluted field were also indicative that metals in the atmospheric deposition were (partly) in a sparingly soluble form, and that release of these non‐labile metals is a slow process. The presence of non‐labile metals should be taken into account when evaluating metal mobility or predicting their transport.
Estimating organic carbon in the soils of Europe for policy support
Authors: Jones R. J. A. , Hiederer R. , Rusco E. , Montanarella L.
Published: September 2005

The estimation of soil carbon content is of pressing concern for soil protection and in mitigation strategies for global warming. This paper describes the methodology developed and the results obtained in a study aimed at estimating organic carbon contents (%) in topsoils across Europe. The information presented in map form provides policy‐makers with estimates of current topsoil organic carbon contents for developing strategies for soil protection at regional level. Such baseline data are also of importance in global change modelling and may be used to estimate regional differences in soil organic carbon (SOC) stocks and projected changes therein, as required for example under the Kyoto Protocol to the United Nations Framework Convention on Climate Change, after having taken into account regional differences in bulk density.

The study uses a novel approach combining a rule‐based system with detailed thematic spatial data layers to arrive at a much‐improved result over either method, using advanced methods for spatial data processing. The rule‐based system is provided by the pedo‐transfer rules, which were developed for use with the European Soil Database. The strong effects of vegetation and land use on SOC have been taken into account in the calculations, and the influence of temperature on organic carbon contents has been considered in the form of a heuristic function. Processing of all thematic data was performed on harmonized spatial data layers in raster format with a 1 km × 1 km grid spacing. This resolution is regarded as appropriate for planning effective soil protection measures at the European level. The approach is thought to be transferable to other regions of the world that are facing similar questions, provided adequate data are available for these regions. However, there will always be an element of uncertainty in estimating or determining the spatial distribution of organic carbon contents of soils.
Sources of trace metals in Ferralsols in New Caledonia
Authors: Becquer T. , Quantin C. , Rotte‐Capet S. , Ghanbaja J. , Mustin C. , Herbillon A. J.
Published: September 2005

One third of New Caledonia is occupied by soils deriving from ultrabasic rocks anomalously rich in trace metals such as Cr, Ni, Mn and Co. The location of the metals present in three samples from a toposequence of Ferralsols was studied by combining selective dissolutions (CaCl2, Cu(NO3)2, hydroxylamine, dithionite–citrate–bicarbonate), examinations with a transmission electron microscope (TEM) equipped with an EDAX device, and X‐ray diffraction and infrared spectroscopy. The behaviour of the metals during dissolution was found to depend on both the type of metal and the location of the samples in the toposequence. In the lowland soil samples derived from transported materials, about 50% of total Mn and Co and a small fraction (< 1%) of total Ni were dissolved in the hydroxylamine reagent. By TEM, the manganese oxide minerals present in one of the lowland samples were found to have chemical compositions similar to those of lithiophorite–asbolane mixed layers identified previously in the subsurface horizons of the laterites capping the landscape where the toposequence occurs. Whatever the location of samples, goethite, i.e. the major constituent of these soils, was found to be the scavenger of the largest proportions of Ni and of about 40% of total Cr. However, this mineral was present as two distinct morphological facies, and each of them had a statistically different chemical composition. The small needle‐shaped goethite, which was abundant in the lowland soils only, was richer in Ni and Si and poorer in Al than the larger acicular one. Our data show that the potential mobility of trace metals in these soils is likely to be controlled by the most soluble phases identified, i.e. the Co‐rich Mn oxides and the Ni‐rich needle‐shaped goethites.
Concentrations of Ag, In, Sn, Sb and Bi, and their chemical fractionation in typical soils in Japan
Authors: Hou H. , Takamatsu T. , Koshikawa M. K. , Hosomi M.
Published: September 2005

We determined concentrations of Ag, In, Sn, Sb and Bi, and fractionated them by sequential extraction procedures, in five Japanese soils: Andosol‐1 (grassland), Andosol‐2 (forest), Cambisol (forest), Fluvisol (vegetable garden) and Regosol (forest). Average concentrations of Ag, In, Sn, Sb and Bi were 0.17 ± 0.08, 0.081 ± 0.019, 2.2 ± 0.5, 0.83 ± 0.32 and 0.32 ± 0.12 mg kg−1, respectively. Average distributions of the chemical fractions (omitting those with an abundance < 5%) were: Ag, residual (60%) > H2O2‐extractable, organically bound (H2O2‐Org) (18%) > metal–organic complex‐bound (Me‐Org) (10%) > amorphous metal oxide‐bound (am‐MeOx) (8.3%); In, residual (61%) > H2O2‐Org (12%) > Me‐Org (8.7%) ≥ crystalline Fe oxide‐bound (cr‐FeOx) (8.2%) > am‐MeOx (7.4%); Sn, residual (40%) > Me‐Org (19%) > carbonate‐bound (12%) > cr‐FeOx (9.0%) > H2O2‐Org (7.8%) > am‐MeOx (6.9%); Sb, residual (34%) > Me‐Org (18%) > am‐MeOx (16%) > cr‐FeOx (8.9%) ≥ H2O2‐Org (8.7%) > easily reducible metal oxide‐bound (re‐MeOx) (6.8%) > carbonate‐bound (6.1%); Bi, am‐MeOx (26%) ≥ H2O2‐Org (26%) > Me‐Org (19%) > residual (17%) > cr‐FeOx (12%). Proportions of the mobilizable (exchangeable + carbonate‐bound + Me‐Org + re‐MeOx) metal fractions were in the order Sn ≥ Sb > Bi > Ag ? In, and Cambisol > Andosol‐2 > Regosol > Andosol‐1 > Fluvisol. The proportions were predicted by multiple regression equations including pH, surface area, C contents, cation exchange capacity and clay content of the soils as independent variables (R2 > 0.96,P< 0.02).
Water repellence and soil aggregate dynamics in a loamy grassland soil as affected by texture
Authors: De Gryze S. , Jassogne L. , Bossuyt H. , Six J. , Merckx R.
Published: September 2005

It has been hypothesized that aggregate stability is partly caused by subcritical (i.e. mild) water repellence. We conducted both a field study at a pasture site and an incubation experiment in the laboratory to characterize the relationship between aggregate dynamics and water repellence. In the field study, we investigated 53 samples from a natural texture gradient for water repellence and aggregation. In the 3‐week incubation experiment, we added wheat straw to crushed soil material from five of the 53 soils representative of the texture gradient (a sandy loam, two loams, a silt loam and a clay loam), and followed changes in aggregate formation and water repellence. Although there was a dramatic increase (P < 0.0001) in aggregation in all the soils during incubation (the mean weight diameter increased from about 300 μm to at least 900 μm), we observed a concomitant increase in water repellence only in the clay loam soil (P = 0.0003). We found no significant correlations between water repellence and aggregation (n = 53, P > 0.05) in the field. Whereas correlation between aggregate formation and texture was weak in the incubation experiment, we found a significant correlation between aggregation and textural parameters in the field. The amount of large macro‐aggregates (> 2000 μm) was positively correlated with clay content (n = 53, r = 0.53, P < 0.001), and negatively with sand content (n = 53, r = −0.46, P < 0.001). These results indicate that (i) microbially induced water repellence might only become apparent when enough easily decomposable substrate is available, (ii) soil texture affects aggregate stabilization rather than aggregate formation, and (iii) aggregate formation is not necessarily associated with an increase in water repellence.
Free radicals, antioxidants, and soil organic matter recalcitrance
Authors: Rimmer D. L.
Published: September 2005

Highly reactive, and potentially damaging, free radicals are readily generated in our oxygen‐rich environment, and are ubiquitous in biological systems. However, plants and animals have evolved protection against them with a range of antioxidant molecules, such as vitamins C and E, many of which are phenolic compounds. These stop the destructive chain reaction of free radical formation by being transformed into unreactive, stable free radicals. The biodegradation of food involves oxidation by free radicals, and is retarded by antioxidants. Similarly, the biodegradation of plant residues in soils involves free radicals; so the questions arise: (i) do soils have antioxidants, and (ii) what function might they have? The evidence suggests that they probably do have antioxidants. First, plant and animal remains added to soils will contain antioxidants. These are likely to persist for a time, particularly tannins, which are polyphenolic compounds with known antioxidant properties and which are relatively resistant to degradation. Second, studies using electron spin resonance spectroscopy have shown that humic materials contain stable semiquinone free radicals, and that their concentration increases as humification progresses. These semiquinone species are most likely to be derived from the reaction of phenolic compounds with reactive radicals. If this is the case, the phenolics are acting as antioxidants, because they are scavenging the reactive free radicals and terminating the oxidative chain reaction responsible for soil organic matter (SOM) degradation. Thus the soil's antioxidant capacity could control the rate of breakdown of organic matter in the more labile pools and could provide a chemical mechanism for the recalcitrance of SOM. Current available evidence for the nature of the recalcitrant pool in SOM is discussed in the light of this hypothesis, and the experimental approaches necessary for testing it are outlined.
Tracing sediment dynamics and sources in eroding rills with rare earth elements
Authors: Lei T. W. , Zhang Q. W. , Zhao J. , Nearing M. A.
Published: September 2005

Eroding rills evolve morphologically in time and space. Most current studies on rill erosion use spatially averaged soil erosion data, providing little information on soil erosion dynamics. A method is proposed to use rare earth elements (REEs) to trace sediment distribution in eroding rills. Laboratory flume simulation experiments were conducted at three flow rates (2, 4 and 8 litres minute−1) and five slope gradients (5, 10, 15, 20 and 25°) with three replicates of each treatment. The rills, of 8 m length, were subdivided into 10 equal segments of 0.8 m length and 0.1 m width, with a different REE applied to each segment. We derived computational formulae for estimating the distribution of eroded amounts along the rills. The actual erosion distribution along rills was then estimated with the data from the experiments. The precision of the REEs for tracing rill erosion was analysed. The results showed that sediment concentration increased with rill length, but the increased rate (the slope of the curve) flattened gradually. Sediment yields increased with slope gradients and flow rates, but the slope gradients had a greater effect on sediment concentration than flow rates, and greater flow rates caused more rill erosion and soil loss under the same slope gradient. The results also demonstrated the feasibility of using REEs to trace the dynamic processes of rill erosion.
A simplified parametric model to describe the magnitude and geometry of soil shrinkage
Authors: Cornelis W. M. , Corluy J. , Medina H. , Hartmann R. , Van Meirvenne M. , Ruiz M. E.
Published: September 2005

Assessing the magnitude and geometry of soil shrinkage is indispensable for sound use and management of swelling and shrinking soils for agriculture and engineering. We have explored a simplified parametric model for the soil shrinkage characteristic curve, which is a measure for the magnitude of soil shrinkage, and tested it against experimental data for a Vertisol and a Lixisol under sugar cane in the Havana province, Cuba. We then applied the model to determine soil consistency limits, including the shrinkage, plastic and structural limits, using the model's third and fourth derivative. We further demonstrated how the model can be used to assess the geometry of shrinkage in terms of the relative crack area and the relative surface subsidence. Excellent matches were obtained between the observations and the fitted model. The shrinkage and structural limits corresponded to distinct changes in the soil shrinkage characteristic curve and were as such considered to be correctly estimated. The accuracy of the estimated plastic limit could, however, not been verified, since data were lacking. Linear regressions with R2 > 0.88 were established relating the shrinkage and plastic limits to the soil's COLE index and the cation exchange capacity. The model could be easily applied to determine the crack area and the surface subsidence. We finally demonstrated how a geometry factor rs plays a crucial role in determining the shrinkage geometry, particularly for rs values ranging from 1 to 3.