Applicability of ground‐penetrating radar as a tool for nondestructive soil‐depth mapping on Pleistocene periglacial slope deposits

Soil depth plays a decisive role in determining soil properties in mountainous regions for ecological site assessment. To evaluate the use of ground‐penetrating radar (GPR) for fast and high‐resolution mapping within mountainous regions, we examined the possibilities and limitations of GPR to determine soil depth over bedrock and to delineate individual substrate layers formed during the Pleistocene in a periglacial environment (Pleistocene periglacial slope deposits, PPSD). Selected catenae in representative subregions of the study area (Dill catchment, SE Rhenish Massif, Germany) have been successfully mapped using GPR. A practicable method was developed using a 400 MHz antenna to reach a mean penetration depth of 1.5 m and to map different substrates and layers of PPSD based on calibrations of the GPR at soil pits along 12 catenae. Colluvium, the three types of PPSD layers, as well as the in situ bedrock could be distinguished in most sections of the GPR surveys. Characteristic GPR facies caused by intrinsic material properties of the different substrates, such as stone content and soil moisture content, could be distinguished in different geomorphologic and lithological settings. A layer‐based velocity distribution was determined for characteristic substrate layers at soil pits enabling us to considerably enhance the accuracy of soil‐depth prediction. Compared to traditionally surveyed soil profiles, our results demonstrate an accuracy of layer thickness surveying within a standard deviation of approx. 0.1 m. It is demonstrated that the combination of GPR with conventional soil‐pit mapping is an efficient and valid method to produce high‐resolution data of substrate distribution.     

Substances interfering with the gas-liquid chromatographic determination of T-2 mycotoxin.

Two substances interfering with the gas-liquid chromatographic (GLC) detection of T-2 mycotoxin were identified as 1-glyceryl-monooleate and 1-glycerylmonolinoleate. These monoglycerides are natural products formed by species of Fusarium growing on cereal grains and are also additives contained in liquid vegetable and animal fats added to the feed mixture. The monoglycerides can be removed from the analytical sample by resolution by thin layer chromatography prior to separation by GLC. Trimethylsilyl ether derivatives of the monoglycerides and T-2 toxin have almost identical retention times on 3% OV-1 columns, whereas the trifluoroacetyl and pentafluoropropionyl derivatives give baseline separation on the same column. The monoglycerides can be misidentified as the T-2 toxin in analyses involbing GLC.     

Use of the pisces database: Power plant aqueous stream compositions

The Power Plant Integrated Systems: Chemical Emissions Studies (PISCES) Database sponsored by the Electric Power Research Institute is a powerful tool for evaluating and comparing the level of trace substances in power plant process streams. In this paper, data are presented on the level of several selected trace metals found in a few of the aqueous streams present in power plants. In addition, a brief discussion of other features of the Database is presented.