Optimized Demineralization Technique for the Measurement of Stable Isotope Ratios of Nonexchangeable H in Soil Organic Matter

To make use of the isotope ratio of nonexchangeable hydrogen (δ²H_{n (nonexchangeable)}) of bulk soil organic matter (SOM), the mineral matrix (containing structural water of clay minerals) must be separated from SOM and samples need to be analyzed after H isotope equilibration. We present a novel technique for demineralization of soil samples with HF and dilute HCl and recovery of the SOM fraction solubilized in the HF demineralization solution via solid-phase extraction. Compared with existing techniques, organic C (C_org) and organic N (N_org) recovery of demineralized SOM concentrates was significantly increased (C_org recovery using existing techniques vs new demineralization method: 58% vs 78%; N_org recovery: 60% vs 78%). Chemicals used for the demineralization treatment did not affect δ²H_n values as revealed by spiking with deuterated water. The new demineralization method minimized organic matter losses and thus artificial H isotope fractionation, opening up the opportunity to use δ²H_n analyses of SOM as a new tool in paleoclimatology or geospatial forensics

Einfluss von NO Emissionen aus dem Boden auf NOx , Ozon und OH in der unteren Troposphäre und die atmosphärische Oxidationseffizienz

<p>Oral presentation (in german) at Jahrestagung der Deutschen Bodenkundlichen Gesellschaft: Böden - eine endliche Ressource. Bonn, Germany</p> <p> </p

Global impact of modelled no emission from soils on related trace gases and evaluation of the no emission from soils

<p>Poster at 10th IGAC Conference: Bridging the Scales in Atmospheric Chemistry: Local to Global (2008). Abstract Th91, Annecy, France (Poster).</p> <p> </p

Global impact of modelled no emission from soils on related trace gases and the atmospheric oxidizing capacity

<p>Oral presentation at 6th EGU General Assembly (2009). Abstract EGU2009–6994, Vienna, Austria.</p> <p> </p

Observed C:N versus predicted C:N ratios.

<p>For every measured C:N ratio (2, 4, 8 and 16 species mixtures) the corresponding calculated C:N ratio is shown across years (2003–2006). The green line gives the fit of an orthogonal regression (intercept 1.03 (SD 0.423); estimated C:N 0.999 (SD 0.043). The blue line gives a linear regression (Intercept 8.1448 (SD 1.434); estimated C:N 0.756 (SD 0.046)). For comparison, identity is given by a black line.</p

C:N ratio versus plant species richness.

<p>GAMLSS (generalized additive model for location scale and shape) model of the molar C:N ratio versus species richness (natural logarithm) of the years 2003–2007. Black line stands for the mean. For better illustration of the variance, percentiles of the standard deviation are given as grey lines. Sown div. = sown diversity, leg = legume.</p

P:K ratio versus plant species richness.

<p>GAMLSS (generalized additive model for location scale and shape) model of the molar P:K ratio versus species richness of the years 2003–2007. Black line stands for the mean. For better illustration of the variance, percentiles of the standard deviation are given as grey lines. Sown div. = sown diversity, leg = legume.</p

MANOVA results on bivariate elemental ratios for the years 2003 to 2007.

<p>For each factor, the Pillai Trace value and its significance level are given as well as all ratios for which the factor effect was significant at p<0.05. Significance levels: p<0.001 = ***, p<0.01 = **, p<0.05 = *, p<0.1 = .</p

C:P ratio versus plant species richness.

<p>GAMLSS (generalized additive model for location scale and shape) model of the molar C:P ratio versus species richness of the years 2003–2007. Black line stands for the mean. For better illustration of the variance, percentiles of the standard deviation are given as grey lines. Sown div. = sown diversity, leg = legume.</p

Comparison of the coefficient of variance of observed C:N and predicted C:N ratios.

<p>The Coefficient of Variation (CV) of measured (oCN) and calculated C:N (pCN) ratios is shown for different diversity levels (2, 4, 8, and 16 species mixtures) separated by years (2003–2006).</p