Elementgehalte (C,N, P,K) wirbelloser Bodentiere

Elemental analyses (C, N, P, K) of invertebrate soil animals Contents of C, N, P and K were analysed in the dry matter of 14 soil organisms (13 species of animals + cysts of protozoa + 1 phytoflagellate) as well as the contents in C and N of further 9 animal species. The investigated material was partly collected in the field, partly raised in laboratory cultures. On the basis of similar C-contens, the investigated organisms may be classified into 4 groups: (1) snails (with shell) 18,3–20,7% C, (2) myriopodes and isopodes 30,3–34,1% C, (3) protozoa, nematodes and oligochaetes 41,2–49,5% C, (4) insects (adult) 48,4–53,3% C. The chemical composition of the organisms is discussed and possible causes of fluctuating concentrations are indicated.     

Importance of storage stability studies in the development of pesticide formulations

Manufacturers of pesticides must know the shelf life of their products for the most varied storage conditions. Accelerated storage tests at elevated temperatures can never completely substitute long-term tests under practical conditions. Nevertheless, a mathematical evaluation of analysis results can considerably raise the meaningfulness of such accelerated tests since predictions of the anticipated active ingredient decomposition under the many different temperature/time conditions are possible. An example is given to demonstrate that for this purpose only a small number of analytical data are needed. Without the degradation reaction order being determined, a sufficiently accurate estimate of the degradation rate can be made. This is demonstrated by a comparison of calculated and found levels of active ingredient content in a long-term storage test.     

Dissipation rates of insecticides in six minor vegetable crops grown on organic soils in Ontario,Canada

Dissipation rates of diazinon, endosulfan, leptophos, methamidophos, methomyl, parathion and pirimicarb were studied on five minor vegetable crops, including cos and head lettuce, endive, cauliflower and Chinese cabbage. Residues from foliar treatment generally followed an exponential rate of decline. The number of days for residues to drop to below acceptable tolerances was highly dependent on the magnitude of the initial residue; large variations in initial residues were observed between years, between insecticides, and between crop types. Residues of five insecticides and two fungicides used in furrow treatments for onions intended for pickling were determined in the onions at harvest and after pickling. Fensulfothion and fonofos levels were below the accepted tolerance of 0.1 mg kg^?1 at harvest, while chlorfenvinphos, chlorpyrifos and ethion were present above this level; fungicide residues were not detected. Following pickling, only ethion residues were still present in the onions at levels greater than 0.1 mg kg^?1.     

Probing electronic transitions in individual carbon nanotubes by Rayleigh scattering

Rayleigh scattering spectra were obtained from individual single-walled carbon nanotubes with the use of a laser-generated visible and near-infrared supercontinuum. This diagnostic method is noninvasive and general for nanoscale objects. The approach permits clear identification of excited states in arbitrary metallic and semiconducting nanotubes. We analyzed spectral lineshapes in relation to the role of excitonic effects and correlated the results with Raman scattering data on individual tubes. The nanotube structure remained the same over distances of tens of micrometers. Small nanotube bundles retained distinct Rayleigh spectroscopic signatures of their component nanotubes, thus allowing the probing of nanotube-nanotube interactions.     

Impact of land‐use changes on soil hydraulic properties of Calcaric Regosols on the Loess Plateau,NW China

Vegetation restoration efforts (planting trees and grass) have been effective in controlling soil erosion on the Loess Plateau (NW China). Shifts in land cover result in modifications of soil properties. Yet, whether the hydraulic properties have also been improved by vegetation restoration is still not clear. The objective of this paper was to understand how vegetation restoration alters soil structure and related soil hydraulic properties such as permeability and soil water storage capacity. Three adjacent sites with similar soil texture, soil type, and topography, but different land cover (black locust forest, grassland, and cropland) were selected in a typical small catchment in the middle reaches of the Yellow River (Loess Plateau). Seasonal variation of soil hydraulic properties in topsoil and subsoil were examined. Our study revealed that land‐use type had a significant impact on field‐saturated, near‐saturated hydraulic conductivity, and soil water characteristics. Specifically, conversion from cropland to grass or forests promotes infiltration capacity as a result of increased saturated hydraulic conductivity, air capacity, and macroporosity. Moreover, conversion from cropland to forest tends to promote the creation of mesopores, which increase soil water‐storage capacity. Tillage of cropland created temporarily well‐structured topsoil but compacted subsoil as indicated by low subsoil saturated hydraulic conductivity, air capacity, and plant‐available water capacity. No impact of land cover conversion on unsaturated hydraulic conductivities at suction > 300 cm was found indicating that changes in land cover do not affect functional meso‐ and microporosity. Our work demonstrates that changes in soil hydraulic properties resulting from soil conservation efforts need to be considered when soil conservation measures shall be implemented in water‐limited regions. For ensuring the sustainability of such measures, the impact of soil conversion on water resources and hydrological processes needs to be further investigated.