Assessment of sampling and analytical uncertainty of trace element contents in arable field soils

Assessment of trace element contents in soils is required in Germany (and other countries) before sewage sludge application on arable soils. The reliability of measured element contents is affected by measurement uncertainty, which consists of components due to (1) sampling, (2) laboratory repeatability (intra-lab) and (3) reproducibility (between-lab). A complete characterization of average trace element contents in field soils should encompass the uncertainty of all these components. The objectives of this study were to elucidate the magnitude and relative proportions of uncertainty components for the metals As, B, Cd, Co, Cr, Mo, Ni, Pb, Tl and Zn in three arable fields of different field-scale heterogeneity, based on a collaborative trial (CT) (standardized procedure) and two sampling proficiency tests (PT) (individual sampling procedure). To obtain reference values and estimates of field-scale heterogeneity, a detailed reference sampling was conducted. Components of uncertainty (sampling person, sampling repetition, laboratory) were estimated by variance component analysis, whereas reproducibility uncertainty was estimated using results from numerous laboratory proficiency tests. Sampling uncertainty in general increased with field-scale heterogeneity; however, total uncertainty was mostly dominated by (total) laboratory uncertainty. Reproducibility analytical uncertainty was on average by a factor of about 3 higher than repeatability uncertainty. Therefore, analysis within one single laboratory and, for heterogeneous fields, a reduction of sampling uncertainty (for instance by larger numbers of sample increments and/or a denser coverage of the field area) would be most effective to reduce total uncertainty. On the other hand, when only intra-laboratory analytical uncertainty was considered, total sampling uncertainty on average prevailed over analytical uncertainty by a factor of 2. Both sampling and laboratory repeatability uncertainty were highly variable depending not only on the analyte but also on the field and the sampling trial. Comparison of PT with CT sampling suggests that standardization of sampling protocols reduces sampling uncertainty, especially for fields of low heterogeneity.     

Methane production potential from anaerobic digestion of plant biomass residues and food waste as substrates

Journal of Material Cycles and Waste Management - This research aimed to evaluate the production of biogas from anaerobic digestion (AD) using swine manure inoculum associated with different...     

Comparison of the statolith structures of <Emphasis Type=Italic>Chironex fleckeri</Emphasis> (Cnidaria,Cubozoa) and <Emphasis Type=Italic>Periphylla periphylla</Emphasis> (Cnidaria,Scyphozoa): a phylogenetic approach

The rhopalia and statocysts of Periphylla periphylla (Péron and Lesueur in Ann Mus Hist Nat Marseille 14:316–366,1809) and Chironex fleckeri Southcott (Aust J Mar Freshw Res 7(2):254–280 1956) were examined histologically and showed several homologous characteristics. Differences in sensory area distribution could be connected to a slightly different functionality of equilibrium sensing. In P. periphylla, the statoliths (crystals) grow independently of each other; whereas in C. fleckeri, one large crystal covers the smaller ones. The structures of both statoliths were examined in detail with single-crystal diffraction, microtomography and diffraction contrast tomography. The single compact statolith of C. fleckeri consisted of bassanite as was previously known only for other rhopaliophoran medusae. An origin area with several small oligocrystals was located in the centre of the cubozoan statolith. The origin areas and the accretion of statoliths are similar in both species. Our results lead to the assumption that the single bassanite statolith of C. fleckeri (Cnidaria, Cubozoa) is a progression of the scyphozoan multiplex statolith. It is therefore suggested that the Cubozoa are derived from a scyphozoan ancestor and are a highly developed taxa within the Rhopaliophora.     

Size Distribution Studies with the Aerosol Spectrometer

It is shown how the Goetz Aerosol Spectrometer can be used to determine the particle size distribution of a specific component of a mixed atmospheric aerosol. The method requires no micrographic counting, but does require that sensitive quantitative chemical analysis methods be available for the compounds of interest. The accuracy of the method and the sensitivity limitations are briefly discussed.