The relevance of particulate organic carbon (POC) for carbon composition in the pore water of drained and rewetted fens of the "Donauried" (South-Germany)

International audienceNumerous studies have dealt with carbon (C) concentrations in Histosols, but there are no studies quantifying the relative importance of all individual C components in pore waters. For this study, measurements were made of all the carbon components (i.e., particulate organic carbon, POC; dissolved organic carbon, DOC; dissolved inorganic carbon, DIC; dissolved methane, CH4) in the soil pore water of a calcareous fen under three different water management regimes (re-wetted, deeply and moderately drained). Pore water was collected weekly or biweekly (April 2004 to April 2006) at depths between 10 and 150 cm. The main results obtained were: (1) DIC (94?280 mg C l?1) was the main C-component. (2) POC and DOC concentrations in the pore water (14?125 mg C l?1 vs. 41?95 mg C l?1) were pari passu. (3) Dissolved CH4 was the smallest C component (0.005?0.9 mg C l?1). Interestingly, about 30% of the POM particles were colonized by microbes indicating that they are active in the internal C transfer in the soil profile ("C-Shuttles"). Consequently, it was concluded that POC is at least as important as DOC for internal soil C turnover. There is no reason to assume significant biochemical differences between POC and DOC as they only differ in size. Therefore, both POC and DOC fractions are essential components of C budgets of peatlands. Furthermore dissolved CO2 in all forms of DIC apparently is an important part of peatland C-balances

Short- and long-term effects of crop residues and of phosphorus fertilization on pearl millet yield on an acid sandy soil in Niger, West Africa

Field experiments were conducted during the rainy seasons of 1990 and 1991 on an acid sandy soil (Luvic Arenosol) in Niger, to assess long-term (since 1986) andshort-term (since 1990) effectsof millet straw (cropresidues) at different amounts (2 t and 6 t ha−1) and modes of application (incorporation, mulching and burning), andofphosphorus (P) fertilization on dry matter yield of pearl millet [Pennisetum glaucum (L.) R. Br.]. Especially long-term, but also short-term application ofcropresidues increased dry matter yield of pearl millet by more than 60%, whereas their omission decreased yield immediately. Compared to mulching or burning, higher yields were obtained with incorporation ofcropresidues. When cropresidues were applied as mulch, dry matter yield was increased to the same extent by 2 t and 6 t ha−1. Similar dry matter yields were achieved with cropresidues (-P) to those with P fertilizer only. An additional yield increase could be obtained by simultaneous application ofcropresiduesand P. Without cropresidues, potassium (K) concentrations in the shoot dry matter indicated K deficiency. With cropresidues considerable amounts of K (15 kg t−1) were provided and raised the K concentrations in the plants to the sufficiency range. Although with cropresidues some P was provided (1.5 kg t−1), the beneficial effects were primarily attributed to increased P acquisition by the millet plants, which was reflected in enhanced root growth in the topsoil (0–10 cm

Vorstellung einer neuen Methode zur Analyse von Bodenaggregaten

Die digitale dynamische Bildanalyse ist ein bildgebendes Verfahren und bietet durch den technischen Fortschritt der letzten Jahre eine Alternative zu den etablierten Methoden der Bestimmung von Partikelgrößenverteilungen. Vor allem durch die direkte Bestimmung der verschiedenen Partikelparameter an jedem einzelnen Partikel besticht die Methode gegenüber anderen Verfahren. In der Bodenkunde gehört die vielversprechende digitale dynamische Bildanalyse aber bisher nicht zur Routineanalytik. Ziel dieser Studie ist es zu untersuchen, ob die digitale dynamische Bildanalyse insbesondere aggregierte Bodenproben reproduzierbar messen kann und ob diese Methode zusätzliche Aggregatinformationen im Vergleich zu konventionell verwendeten liefert. Wir möchten die Ergebnisse von sieben verschiedenen Bodenproben vorstellen, die eine weite Spanne der Eigenschaften abdecken, die die Aggregatstabilität im Boden beeinflussen (pH, Corg und Textur). Die dabei erhaltenen Ergebnisse wurden mit denen aus einer etablierten Methode zur Bestimmung der Aggregierung (Mean Weighted Diameter) verglichen. Die Untersuchungen wurden in wässriger Suspension der Bodenproben mit QICPIC (Sympatec GmbH) durchgeführt, einem digitalen, dynamischen Bildanalysator. Um die Messbereiche des Gerätes optimal ausnutzen zu können wurden die Proben durch Nasssiebung vorfraktioniert (Fraktion < 63 µm und 63 – 1000 µm). Zunächst wurde die Partikelgrößenverteilung der Bodenproben im aggregierten Zustand bestimmt. Im Anschluss wurden die Proben je nach untersuchter Fraktion mittels Ultraschallapplikation in mehreren Schritten (1 J/cm3 bis 300 J/cm3) disaggregiert und die Partikelgrößenverteilung erneut bestimmt. Die Ergebnisse der digitalen dynamischen Bildanalyse sind mit den Ergebnissen basierend auf Nasssiebung und danach berechnetem MWD vergleichbar, werden jedoch höher aufgelöst dargestellt. Allerdings sind Ergebnisse über Partikel kleiner 18 µm mit großen Unsicherheiten behaftet. Außerdem beobachteten wir deutliche Unterschiede hinsichtlich der Antwort der Bodenproben auf Ultraschallenergie-Zugabe. Das Messverfahren ermöglicht eine kontinuierliche Analyse des Aggregatzerfalls. Weitere neue Einblicke in die Eigenschaften kleiner Bodenaggregate ermittelt die Analyse der Sphärizität (d.h. Rundheit) der Partikel. Schon jetzt können wir deutliche Unterschiede in der Sphärizität der Aggregate zwischen Ober- und Unterbodenproben belegen. Die Ergebnisse dazu werden ebenfalls vorgestellt und diskutiert

Ultrasound settings significantly alter arterial lumen and wall thickness measurements

Background. Flow-mediated dilation (FMD) and carotid intima-medial thickness (CIMT), measured by ultrasound, are widely used to test the efficacy of cardioprotective interventions. Although assessment methods vary, automated edge-detecting image analysis software is routinely used to measure changes in FMD and CIMT. We aimed to quantify the effect that commonly adjusted ultrasound settings have on arterial lumen and wall thickness measurements made with CIMT measurement software. Methods. We constructed phantom arteries from a tissue-mimicking agar compound and scanned them in a water bath with a 10 MHz multi-frequency linear-array probe attached to a high-resolution ultrasound machine. B-mode images of the phantoms were recorded with dynamic range (DR) and gain set at five decibel (dB) increments from 40 dB to 60 dB and -10 dB to +10 dB respectively. Lumen diameter and wall-thickness were measured off-line using CIMT measurement software. Results. Lumen measurements: there was a strong linear relationship between DR and gain and measured lumen diameter. For a given gain level, a 5 dB increase in DR reduced the measured lumen diameter by 0.02 ± 0.004 mm (p \u3c 0.001). For a given DR level, a 5 dB increase in gain reduced measured lumen diameter by 0.04 ± 0.004 mm (p \u3c 0.001). A 5 mm increase in distance between the ultrasound probe and the artery reduced measured lumen diameter by 0.04 ± 0.03 mm (p \u3c 0.001). CIMT measurements: For a fixed gain level, a 5 dB increase in DR increased measured wall thickness by 0.003 ± 0.002 mm (p \u3c 0.001). The effects of increasing gain were not consistent and appeared to vary depending on the distance between the artery and the ultrasound probe and the thickness of the artery wall. Conclusion. DR, gain and probe distance significantly alter lumen diameter and CIMT measurements made using image analysis software. When CIMT and FMD are used to test the efficacy of cardioprotective interventions, the DR, gain and probe position used to record baseline scans should be documented and replicated in post-treatment scans in individual trial subjects. If more than one sonographer or imaging centre is used to collect data, the study protocol should document specific DR and gain settings to be used in all subjects

Remote sensing and transect-based retrieval of spatial soil and terrain (SOTER) information in semi-arid Niger

A methodology for retrieval and mapping of spatial soil and terrain data based on the SOTER approach has been developed for semi-arid Niger. Remote sensing technics and detailed ground transect investigations are used, and the collected data are integrated into a SOTER database and a Geographic Information System. Transect selection, their realization and the related problems with transect-based calculations are discussed. The method permits estimations of soil type coverages, present land use and soil degradation at different scale levels. The significant dynamics of soil redistribution are pointed out and attributed to present and past erosion events

Watershed Scale Impacts of Buffers and Upland Conservation Practices on Agrochemical Delivery to Streams

Conservation buffers are designed to reduce sediment and agrichemical runoff to surface water. Much is known about plot and field scale effectiveness of buffers; but little is known about their watershed scale impact. Our objective was to estimate the watershed scale impact of grass buffers by comparing sediment and agrichemical losses from two adjacent 141-165 hectare watersheds, one with conservation buffers and one without. Rainfall derived runoff events from 2002-2003 were monitored for water runoff, TSS, phosphorous and atrazine loss. A conservation-watershed included 0.8 km of grass buffers and 0.8 km of riparian forest buffer, ridge-tilled corn, corn-beans-alfalfa rotation, terraces and grassed waterways. A control-watershed had no buffers, disk-tilled, continuous corn and grassed waterways. The same application rate and method for atrazine to corn was used in each watershed. Total rainfall during the April-June monitoring period was similar in 2002 and 2003; however, the conservation-watershed produced only 27 mm of runoff, compared to 47 mm from the control. Over two years, TSS and phosphorous losses per hectare were reduced by 97% and 95%, respectively, in the conservation-watershed. Atrazine loss per hectare was 57% less in the conservation watershed. A separation technique showed that for 2002 other conservation practices reduced TSS by 84% and buffers reduced TSS by an additional 13% compared to the control. Similarly, other conservation practices reduced atrazine losses by 29% and buffers accounted for an additional 31%. On a watershed scale buffers can add benefit to a conservation system

Soil development on marine terraces near Metaponto (Gulf of Taranto, southern Italy)

For decades, the marine terraces in the Metaponto area have been the subject of discussions concerning their number, sedimentology, genesis and age This paper contributes to landscape history reconstruction from a pedogenetic view. The marine terraces are generally covered by loamy sediments, which have been interpreted in previous works as lagoonal and/or alluvial sediments, deposited shortly after the emergence of the land surface above sea level. Pedogenetic investigation, including field observations (e g. soil colour, intensity of weathering, precipitation of secondary carbonates) and Fe(d)/Fe(t) ratio, silt/clay ratio and carbonate content, reveals that the usual sedimentation history on the terraces includes a period of soil formation between the deposition of the marine and that of the alluvial sediments Most likely, soil formation began after the relative sea level maximum within the same interglacial during which the marine terrace formed Later, alluvial sediments accumulated during a time of periodic flooding, while soil development in the underlying marine sediments probably continued at reduced rates One central question of this study is whether soil formation indicates progressive ages of the terraces The complex landscape history involving several sedimentation and erosion phases makes the correlation of soil development stages with terrace ages difficult. Nevertheless, maximum Fed/Fet ratios and (Ca + Mg + K + Na)/Al ratios of the soils developed in the different sediments plotted vs. assumed terrace age indicate increasing soil development. The relationship between Fed/Fet ratios and terrace age can be best described by power (R(2) = 0.89) or logarithmic functions (R(2) = 072), both describing a strong increase in pedogenic iron in the first 100 ka which slows down afterwards. (Ca + Mg + K + Na)/Al ratios follow a logarithmic decrease with time (R(2) = 099), indicating progressive silicate weathering, associated with element release and leaching. (C) 2009 Elsevier Ltd and INQUA. All rights reserved

Freeze-drying of ovalbumin loaded mesoporous silica nanoparticle vaccine formulation increases antigen stability under ambient conditions

Amino functionalised mesoporous silica nanoparticles (AM-41) have been identified as a promising vaccine delivery material. The capacity of AM-41 to stabilise vaccine components at ambient temperature (23-27°C) was determined by adsorbing the model antigen ovalbumin (OVA) to AM-41 particles (OVA-41). The OVA-41 was successfully freeze-dried using the excipients 5% trehalose and 1% PEG8000. The immunological activity of OVA and the nanoparticle structure were maintained following two months storage at ambient temperature. The results of immunisation studies in mice with reconstituted OVA-41 demonstrated the induction of humoral and cell-meditated immune responses. The capacity of AM-41 particles to facilitate ambient storage of vaccine components without the loss of immunological potency will underpin the further development of this promising vaccine delivery platform.Karishma T. Mody, Donna Mahony, Antonino S. Cavallaro, Frances Stahr Shi Zhang Qiao, Timothy J. Mahony, Neena Mitte