Regional variation in the microhardness and mineralization of vertebrae from brown and rainbow trout

Regional variation in properties of vertebral bone from brown Salmo trutta and rainbow trout Oncorhychus mykiss were explored by using microhardness tests. Statistically-significant positive correlations were identified between the microhardness of bone and its mineral content. In both brown and rainbow trout, the vertebrae from the caudal region were harder than those of the trunk region. There was a significant difference between the species; microhardness of bone from vertebrae of rainbow trout was greater than those from brown trout.

Secondary uranium mineralization in southern Finland and its relationship to recent glacial events

Uranium series dating has been carried out on secondary uranyl silicate minerals formed during sub-glacial and post-glacial weathering of Proterozoic uraninite ores in south west Finland. The samples were obtained from two sites adjacent to the Salpauselkä III ice marginal formation and cover a range of depths, from the surface to more than 60 m. Measured ages fall into three distinct groups, 70–100 ka, 28–36 ka and < 2500 yr. The youngest set is associated with surface exposures and the crystals display clear evidence of re-working. The most likely trigger for uranium release at depths below the surface weathering zone is intrusion of oxidising glacial melt water. The latter is often characterised by very high discharge rates along channels, which close once the overpressure generated at the ice margin is released. There is excellent correspondence between the two Finnish sites and published data for similar deposits over a large area of southern and central Sweden. None of the seventy samples analysed gave a U–Th age between 40 and 70 ka; a second hiatus is apparent at 20 ka, coinciding with the Last Glacial Maximum. Thus, the process responsible for uranyl silicate formation was halted for significant periods, owing to a change in geochemical conditions or the hydrogeological regime. These data support the presence of interstadial conditions during the Early and Middle Weichselian since in the absence of major climatic perturbations the uranium phases at depth are stable. When viewed in conjunction with proxy data from mammoth remains it would appear that the region was ice-free prior to the Last Glacial Maximum.

Decomposition in soil and chemical characteristics of pollen

The input to soils made by pollen and its subsequent mineralization has rarely been investigated from a soil microbiological point of view even though the small but significant quantities of C and N in pollen may make an important contribution to nutrient cycling. The relative resistance to decomposition of pollen exines (outer layers) has led to much of the focus of pollen in soil being on its preservation for archaeological and palaeo-ecological purposes. We have examined aspects of the chemical composition and decomposition of pollen from birch (Betula alba) and maize (Zea mays) in soil. The relatively large N contents, small C-to-N ratios and large water-soluble contents of pollen from both species indicated that they would be readily mineralized in soil. When added to soil and incubated at 16 degrees C an amount of C equivalent to 22-26% of the added pollen C was lost as CO2 within 22 days, with the Z. mays pollen decomposing faster. For B. alba pollen, the water-soluble fraction decomposed faster than the whole pollen and the insoluble fraction decomposed more slowly over 22 days. By contrast, there were no significant differences in the decomposition rates of the different fractions from Z. mays pollen. Solid-state C-13 nuclear magnetic resonance (NMR) revealed no gross chemical differences between the pollen of these two species, with strong resonances in the alkyl- and methyl-C region (0-45 p.p.m.) indicative of aliphatic compounds, the O-alkyl-C (60-90 p.p.m.) and the acetal- and ketal-C region (90-110 p.p.m.) indicative of polysaccharides, and the carbonyl-C region indicative of peptides and carboxylic acids. In addition, both pollens gave a small but distinct resonance at 55 p.p.m. attributed to N-alkyl-C. The resonances attributed to polysaccharides were lost completely or substantially reduced after decomposition.

Modeling the mechanisms that control in-stream dissolved organic carbon dynamics in upland and forested catchments

[1] We present a new, process-based model of soil and stream water dissolved organic carbon (DOC): the Integrated Catchments Model for Carbon (INCA-C). INCA-C is the first model of DOC cycling to explicitly include effects of different land cover types, hydrological flow paths, in-soil carbon biogeochemistry, and surface water processes on in-stream DOC concentrations. It can be calibrated using only routinely available monitoring data. INCA-C simulates daily DOC concentrations over a period of years to decades. Sources, sinks, and transformation of solid and dissolved organic carbon in peat and forest soils, wetlands, and streams as well as organic carbon mineralization in stream waters are modeled. INCA-C is designed to be applied to natural and seminatural forested and peat-dominated catchments in boreal and temperate regions. Simulations at two forested catchments showed that seasonal and interannual patterns of DOC concentration could be modeled using climate-related parameters alone. A sensitivity analysis showed that model predictions were dependent on the mass of organic carbon in the soil and that in-soil process rates were dependent on soil moisture status. Sensitive rate coefficients in the model included those for organic carbon sorption and desorption and DOC mineralization in the soil. The model was also sensitive to the amount of litter fall. Our results show the importance of climate variability in controlling surface water DOC concentrations and suggest the need for further research on the mechanisms controlling production and consumption of DOC in soils.

Enhanced phytoextraction: II. Effect of EDTA and citric acid on heavy metal uptake by Helianthus annuus from a calcareous soil

High biomass producing plant species, such as Helianthus annuus, have potential for removing large amounts of trace metals by harvesting the aboveground biomass if sufficient metal concentrations in their biomass can be achieved. However, the low bioavailability of heavy metals in soils and the limited translocation of heavy metals to the shoots by mosthigh biomass producing plant species limit the efficiency of the phytoextraction process. Amendment of a contaminated soil with ethylene diamine letraacetic acid (EDTA) or citric acid increases soluble heavy metal concentrations, potentially rendering them more available for plant uptake. This article discusses the effects of EDTA and citric acid on the uptake of heavy metals and translocation to aboveground harvestable plant parts in Helianthus annuus. EDTA was included in the research for comparison purposes in our quest for less persistent alternatives, suitable for enhanced phytoextraction. Plants were grown in a calcareous soil moderately contaminated with Cu, Pb, Zn, and Cd and treated with increasing concentrations of EDTA (0. 1, 1, 3, 5, 7, and 10 mmol kg(-1) soil) or citric acid (0. 01, 0. 05, 0.25, 0.442, and 0.5 mol kg(-1) soil). Heavy metal concentrations in harvested shoots increased with EDTA concentration but the actual amount of phytoextracted heavy metals decreased at high EDTA concentrations, due to severe growth depression. Helianthus annuus suffered heavy metal stress due to the significantly increased bioavailable metal fraction in the soil. The rapid mineralization of citric acid and the high buffering capacity of the soil made citric acid inefficient in increasing the phytoextracted amounts of heavy metals. Treatments that did not exceed the buffering capacity of the soil (< 0.442 mol kg(-1) soil) did not result in any significant increase in shoot heavy metal concentrations. Treatments with high concentrations resulted in a dissolution of the carbonates and compaction of the soil. These physicochemical changes caused growth depression of Helianthus annuus. EDTA and citric acid added before sowing of Helianthus annuus did not appear to be efficient amendments when phytoextraction of heavy metals from calcareous soils is considered.

Enhanced phytoextraction: In search of EDTA alternatives

Enhanced phytoextraction proposes the use of soil amendments to increase the heavy-metal content of above-ground harvestable plant tissues. This study compares the effect of synthetic aminopolycarboxylic acids [ethylenediamine tetraacetatic acid (EDTA), nitriloacetic acid (NTA), and diethylenetriamine pentaacetic acid (DTPA)] with a number of biodegradable, low-molecular weight, organic acids (citric acid, ascorbic acid, oxalic acid, salicylic acid, and NH4 acetate) as potential soil amendments for enhancing phytoextraction of heavy metals (Cu, Zn, Cd, Pb, and Ni) by Zea mays. The treatments in this study were applied at a dose of 2 mmol/kg(-1) 1 d before sowing. To compare possible effects between presow and postgermination treatments, a second smaller experiment was conducted in which EDTA, citric acid, and NH4 acetate were added 10 d after germination as opposed to 1 d before sowing. The soil used in this screening was a moderately contaminated topsoil derived from a dredged sediment disposal site. This site has been in an oxidized state for more than 8 years before being used in this research. The high carbonate, high organic matter, and high clay content characteristic to this type of sediment are thought to suppress heavy-metal phytoavailability. Both EDTA and DTPA resulted in increased levels of heavy metals in the above-ground biomass. However, the observed increases in uptake were not as large as reported in the literature. Neither the NTA nor organic acid treatments had any significant effect on uptake when applied prior to sowing. This was attributed to the rapid mineralization of these substances and the relatively low doses applied. The generally low extraction observed in this experiment restricts the use of phytoextraction as an effective remediation alternative under the current conditions, with regard to amendments used, applied dose (2 mmol/kg(-1) soil), application time (presow), plant species (Zea mays), and sediment (calcareous clayey soil) under study.

An application of the GLUE methodology for estimating the parameters of the INCA-N model

The conceptual and parameter uncertainty of the semi-distributed INCA-N (Integrated Nutrients in Catchments-Nitrogen) model was studied using the GLUE (Generalized Likelihood Uncertainty Estimation) methodology combined with quantitative experimental knowledge, the concept known as 'soft data'. Cumulative inorganic N leaching, annual plant N uptake and annual mineralization proved to be useful soft data to constrain the parameter space. The INCA-N model was able to simulate the seasonal and inter-annual variations in the stream-water nitrate concentrations, although the lowest concentrations during the growing season were not reproduced. This suggested that there were some retention processes or losses either in peatland/wetland areas or in the river which were not included in the INCA-N model. The results of the study suggested that soft data was a way to reduce parameter equifinality, and that the calibration and testing of distributed hydrological and nutrient leaching models should be based both on runoff and/or nutrient concentration data and the qualitative knowledge of experimentalist. (c) 2006 Elsevier B.V. All rights reserved.

Presubmergence and green manure affect the transformations of nitrogen-15-labeled urea under lowland soil conditions

The effect of presubmergence and green manuring on various processes involved in [N-15]-urea transformations were studied in a growth chamber after [N-15]-urea application to floodwater. Presubmergence for 14 days increased urea hydrolysis rates and floodwater pH, resulting in higher NH3 volatilization as compared to without presubmergence. Presubmergence also increased nitrification and subsequent denitrification but lower N assimilation by floodwater algae caused higher gaseous losses. Addition of green manure maintained higher NH4+-N concentration in floodwater mainly because of lower nitrification rates but resulted in highest NH3 volatilization losses. Although green manure did not affect the KCl extractable NH4+-N from applied fertilizer, it maintained higher NH4+-N content due to its decomposition and increased mineralization of organic N. After 32 days about 36.9% (T-1), 23.9% (T-2), and 36.4% (T-3) of the applied urea N was incorporated in the pool of soil organic N in treatments. It was evident that the presubmergence has effected the recovery of applied urea N.

Decomposition in soil and chemical characteristics of pollen

The input to soils made by pollen and its subsequent mineralization has rarely been investigated from a soil microbiological point of view even though the small but significant quantities of C and N in pollen may make an important contribution to nutrient cycling. The relative resistance to decomposition of pollen exines (outer layers) has led to much of the focus of pollen in soil being on its preservation for archaeological and palaeo-ecological purposes. We have examined aspects of the chemical composition and decomposition of pollen from birch (Betula alba) and maize (Zea mays) in soil. The relatively large N contents, small C-to-N ratios and large water-soluble contents of pollen from both species indicated that they would be readily mineralized in soil. When added to soil and incubated at 16 degrees C an amount of C equivalent to 22-26% of the added pollen C was lost as CO2 within 22 days, with the Z. mays pollen decomposing faster. For B. alba pollen, the water-soluble fraction decomposed faster than the whole pollen and the insoluble fraction decomposed more slowly over 22 days. By contrast, there were no significant differences in the decomposition rates of the different fractions from Z. mays pollen. Solid-state C-13 nuclear magnetic resonance (NMR) revealed no gross chemical differences between the pollen of these two species, with strong resonances in the alkyl- and methyl-C region (0-45 p.p.m.) indicative of aliphatic compounds, the O-alkyl-C (60-90 p.p.m.) and the acetal- and ketal-C region (90-110 p.p.m.) indicative of polysaccharides, and the carbonyl-C region indicative of peptides and carboxylic acids. In addition, both pollens gave a small but distinct resonance at 55 p.p.m. attributed to N-alkyl-C. The resonances attributed to polysaccharides were lost completely or substantially reduced after decomposition.

Impacts of climate change on in-stream nitrogen in a lowland chalk stream: An appraisal of adaptation strategies

The impacts of climate change on nitrogen (N) in a lowland chalk stream are investigated using a dynamic modelling approach. The INCA-N model is used to simulate transient daily hydrology and water quality in the River Kennet using temperature and precipitation scenarios downscaled from the General Circulation Model (GCM) output for the period 1961-2100. The three GCMs (CGCM2, CSIRO and HadCM3) yield very different river flow regimes with the latter projecting significant periods of drought in the second half of the 21st century. Stream-water N concentrations increase over time as higher temperatures enhance N release from the soil, and lower river flows reduce the dilution capacity of the river. Particular problems are shown to occur following severe droughts when N mineralization is high and the subsequent breaking of the drought releases high nitrate loads into the river system. Possible strategies for reducing climate-driven N loads are explored using INCA-N. The measures include land use change or fertiliser reduction, reduction in atmospheric nitrate and ammonium deposition, and the introduction of water meadows or connected wetlands adjacent to the river. The most effective strategy is to change land use or reduce fertiliser use, followed by water meadow creation, and atmospheric pollution controls. Finally, a combined approach involving all three strategies is investigated and shown to reduce in-stream nitrate concentrations to those pre-1950s even under climate change. (c) 2006 Elsevier B.V. All rights reserved.

Modelling the inorganic nitrogen behaviour in a small Mediterranean forested catchment, Fuirosos (Catalonia)

The aim of this work was to couple a nitrogen (N) sub-model to already existent hydrological lumped (LU4-N) and semi-distributed (LU4-R-N and SD4-R-N) conceptual models, to improve our understanding of the factors and processes controlling nitrogen cycling and losses in Mediterranean catchments. The N model adopted provides a simplified conceptualization of the soil nitrogen cycle considering mineralization, nitrification, immobilization, denitrification, plant uptake, and ammonium adsorption/desorption. It also includes nitrification and denitrification in the shallow perched aquifer. We included a soil moisture threshold for all the considered soil biological processes. The results suggested that all the nitrogen processes were highly influenced by the rain episodes and that soil microbial processes occurred in pulses stimulated by soil moisture increasing after rain. Our simulation highlighted the riparian zone as a possible source of nitrate, especially after the summer drought period, but it can also act as an important sink of nitrate due to denitrification, in particular during the wettest period of the year. The riparian zone was a key element to simulate the catchment nitrate behaviour. The lumped LU4-N model (which does not include the riparian zone) could not be validated, while both the semi-distributed LU4-R-N and SD4-R-N model (which include the riparian zone) gave satisfactory results for the calibration process and acceptable results for the temporal validation process.

Effects of biosolids from tomato processing on soil fertility and wheat growth in a Greek alfisol

The effects of biosolids from tomato processing on soil properties and wheat growth were investigated in an Alfisol from central Greece. Biosolids were mixed with soil from the surface (Ap) or subsurface (Bt) horizon in plastic containers at rates of 1%, 5%, and 10% by dry weight (d.w.; equivalent to 10, 50, and 100 Mg ha–1). Biosolid treatments were compared to an NH4Cl application (50 mg N kg–1) and an untreated control in (1) a 102 d incubation experiment at 28°C to determine biosolid nitrification potential and (2) a 45 d outdoor experiment to evaluate effects on soil fertility and wheat growth. Mineralization of biosolids in the incubation experiment resulted in accumulation of nitrate-N and indicated that biosolids were able to supply N that was in excess of crop needs in treatments of 5% and 10%. After 45 d of wheat growth, available soil nutrients (N, P) and P uptake by wheat were distinctly lower in the Bt than in the Ap horizon. However, soil pH, electrical conductivity, organic matter, total N, nitrate-N, extractable P, and exchangeable K increased with increasing rate of biosolid application in both soils. These were followed by corresponding increases in wheat nutrient uptake and biomass production, thus demonstrating the importance of this organic material for sustaining production in soils of low immediate fertility. Compared to the NH4Cl treatment (50 kg N ha–1 equivalent), biosolid application rates of 5% and 10% had higher available soil nutrients, similar or higher nutrient uptake and higher wheat biomass. But only an application of 10% biosolids provided sufficient N levels for wheat in the surface soil, and even higher applications were required for providing sufficient N and P in the Bt horizon.

Biodegradation of polyethylene glycol (PEG) in three tropical soils using radio labelled PEG

Polyethylene glycol (PEG) may be added to forage based diets rich in tannins for ruminant feeding because it binds to tannins and thus prevent the formation of potentially indigestible tannin-protein complexes. The objective of this work was to determine the in vitro biodegradation (mineralization, i.e., complete breakdown of PEG to CO2) rate of PEG. C-14-Polyethylene glycol (C-14-PEG) was added to three different tropical soils (a sandy clay loam soil, SaCL; a sandy clay soil, SaC; and a sandy loam soil, SaL) and was incubated in Bartha flasks. Free PEG and PEG bound to tannins from a tannin rich local shrub were incubated under aerobic conditions for up to 70 days. The biodegradation assay monitored the (CO2)-C-14 evolved after degradation of the labelled PEG in the soils. After incubation, the amount of (CO2)-C-14 evolved from the C-14-PEG application was low. Higher PEG mineralization values were found for the soils with higher organic matter contents (20.1 and 18.6 g organic matter/kg for SaCL and SaC, respectively) than for the SaL soil (11.9 g organic matter/kg) (P < 0.05). The extent of mineralization of PEG after 70 days of incubation in the soil was significantly lower (P < 0.05) when it was added as bound to the browse tannin than in the free form (0.040 and 0.079, respectively). (c) 2005 Elsevier B.V. All rights reserved.

Exploring options for managing strategies for pea-barley intercropping using a modeling approach

A modeling Study was carried out into pea-barley intercropping in northern Europe. The two objectives were (a) to compare pea-barley intercropping to sole cropping in terms of grain and nitrogen yield amounts and stability, and (b) to explore options for managing pea-barley intercropping systems in order to maximize the biomass produced and the grain and nitrogen yields according to the available resources, such as light, water and nitrogen. The study consisted of simulations taking into account soil and weather variability among three sites located in northern European Countries (Denmark, United Kingdom and France), and using 10 years of weather records. A preliminary stage evaluated the STICS intercrop model's ability to predict grain and nitrogen yields of the two species, using a 2-year dataset from trials conducted at the three sites. The work was carried out in two phases, (a) the model was run to investigate the potentialities of intercrops as compared to sole crops, and (b) the model was run to explore options for managing pea-barley intercropping, asking the following three questions: (i) in order to increase light capture, Would it be worth delaying the sowing dates of one species? (ii) How to manage sowing density and seed proportion of each species in the intercrop to improve total grain yield and N use efficiency? (iii) How to optimize the use of nitrogen resources by choosing the most suitable preceding crop and/or the most appropriate soil? It was found that (1) intercropping made better use of environmental resources as regards yield amount and stability than sole cropping, with a noticeable site effect, (2) pea growth in intercrops was strongly linked to soil moisture, and barley yield was determined by nitrogen uptake and light interception due to its height relative to pea, (3) sowing barley before pea led to a relative grain yield reduction averaged over all three sites, but sowing strategy must be adapted to the location, being dependent on temperature and thus latitude, (4) density and species proportions had a small effect on total grain yield, underlining the interspecific offset in the use of environmental growth resources which led to similar total grain yields whatever the pea-barley design, and (5) long-term strategies including mineralization management through organic residue supply and rotation management were very valuable, always favoring intercrop total grain yield and N accumulation. (C) 2009 Elsevier B.V. All rights reserved.

Natural products as alternative treatments for metabolic bone disorders and for maintenance of bone health

Bone metabolism involves a complex balance between the deposition of matrix and mineralization and resorption. There is now good evidence that dietary components and herbal products can influence these processes, particularly by inhibiting bone resorption, thus having beneficial effects on the skeleton. For example, it has been reported that a number of common vegetables, including onion, garlic and parsley, can inhibit bone resorption in ovariectomized rats. Essential oils derived from sage, rosemary, thyme and other herbs inhibit osteoclast activity in vitro and in vitro and leading to an increase in bone mineral density. Soya, a rich source of isoflavones, has shown promising results and epidemiological evidence to support a use in maintaining bone health, and various traditional herbal formulae in Chinese and Ayurvedic medicine also have demonstrable effects in pharmacological models of osteoporosis. Recently, cannabinoids have been described as having positive effects on osteoblast differentiation, and the presence of cannabinoid receptors in bone tissue indicates a more complex role in bone metabolism than previously thought. The first part of this review briefly discusses normal bone metabolism and disorders caused by its disruption, with particular reference to osteoporosis and current pharmacological treatments. The effects of natural products on bone and connective tissue are then discussed, to include items of diet, herbal extracts and food supplements, with evidence for their efficacy outlined. Copyright (c) 2006 John Wiley & Sons, Ltd.