Fate of the veterinary antibiotic 14C-difloxacin in soil including simultaneous amendment of pig manure with the focus on non-extractable residues

The fate of ¹⁴C-labeled difloxacin (¹⁴C-DIF) was studied in time course experiments after application on soil (Ap horizon of silt loam) and amendment of authentic DIF containing pig manure (146 mL kg^?1; 4.17 MBq kg^?1; 0.85 mg kg^?1) or water (124 mL kg^?1; 0.42 MBq kg^?1; 0.09 mg kg^?1) for 56 and 120 days of incubation, respectively.

Mineralization of ¹⁴C-DIF was below 0.2% in both experiments after 56 days or 120 days. In the course of the experiments, portions of extractable radioactivity (Accelerated Solvent Extraction (ASE); acetonitrile-water) decreased to 19–21% depending only little on manure amendment. Non-extractable residues of ¹⁴C-DIF increased to 70–74% after 56 days and 120 days, respectively, and therefore were the main route of ¹⁴C-DIF in soil. According to radioanalytical HPLC and LC-MS/MS, only the parent compound was found in all extracts over the whole time of the experiment. According to fractionation of the non-extractable residues (NER) into particle size fractions, ¹⁴C portions were associated to the water used for fractionation, the silt and clay fractions, whereas no radioactivity was detected in the sand fraction. The majority of ¹⁴C was found within the clay fractions.

Fractionation of humic components showed that radioactivity derived from ¹⁴C-DIF was associated with humic acids, fulvic acids, humins and minerals and very little with soluble, non-humic HCl fraction. The highest portions of radioactivity were found in the fulvic acid fraction. Results obtained by size exclusion chromatography (SEC) of the purified fulvic acids were similar for every sample analyzed. One large portion of ¹⁴C co-eluted with fulvic acids of a molecular weight below 910 g mol^?1. Both fractionation methods demonstrated that the parent compound DIF or initial metabolites were rapidly integrated into humic materials and, thus, were major components of NER.     

Occurrence of aminopolycarboxylates in the aquatic environment of Germany

Aminopolycarboxylic acids, such as ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), 1,3-propylenediaminetetraacetic acid (1,3-PDTA), beta-alaninediacetic acid (beta-ADA), and methylglycinediacetic acid (MGDA), are used in large quantities in a broad range of industrial applications and domestic products in order to solubilize or inactivate various metal ions by complex formation. Due to the wide field of their application, their high polarity and partly low degradability, these substances reach the aquatic environment at considerable concentrations (in the microg/L-range) and have also been detected in drinking water. This review evaluates and summarizes the results of long-term research projects, monitoring programs, and published papers concerning the pollution of the aquatic environment by aminopolycarboxylates in Germany. Concentrations and loads of aminopolycarboxylates are presented for various types of water including industrial and domestic waste waters, surface waters (rivers and lakes), raw waters, and drinking waters.     

Radioactive materials in biosolids: national survey, dose modeling, and publicly owned treatment works (POTW) guidance

The Nuclear Regulatory Commission (NRC) announced the availability of three new documents concerning radioactive materials in sewage sludge and ash from publicly owned treatment works (POTW). One of the documents is a report presenting the results of a volunteer survey of sewage sludge and ash samples provided by 313 POTWs. The second document is a dose modeling document, using multiple exposure pathway modeling focused on a series of generic scenarios, to track possible exposure of POTW workers and members of the general public to radioactivity from the sewage sludge or ash. The third document is a guidance report providing recommendations on the management of radioactivity in sewage sludge and ash for POTW owners and operators. This paper explains how radioactive materials enter POTWs, provides criteria for evaluating levels of radioactive material in sludge and ash, and gives a summary of the results of the survey and dose modeling efforts.     

A Special Vegetation Index for the Weed Detection in Sensor Based Precision Agriculture

Many technologies in precision agriculture (PA) require image analysis and image- processing with weed and background differentiations. The detection of weeds on mulched cropland is one important image-processing task for sensor based precision herbicide applications. The article introduces a special vegetation index, the Difference Index with Red Threshold (DIRT), for the weed detection on mulched croplands. Experimental investigations in weed detection on mulched areas point out that the DIRT performs better than the Normalized Difference Vegetation Index (NDVI). The result of the evaluation with four different decision criteria indicate, that the new DIRT gives the highest reliability in weed/background differentiation on mulched areas. While using the same spectral bands (infrared and red) as the NDVI, the new DIRT is more suitable for weed detection than the other vegetation indices and requires only a small amount of additional calculation power. The new vegetation index DIRT was tested on mulched areas during automatic ratings with a special weed camera system. The test results compare the new DIRT and three other decision criteria: the difference between infrared and red intensity (Diff), the soil-adjusted quotient between infrared and red intensity (Quotient) and the NDVI. The decision criteria were compared with the definition of a worse case decision quality parameter Q, suitable for mulched croplands. Although this new index DIRT needs further testing, the index seems to be a good decision criterion for the weed detection on mulched areas and should also be useful for other image processing applications in precision agriculture. The weed detection hardware and the PC program for the weed image processing were developed with funds from the German Federal Ministry of Education and Research (BMBF).     

Future intensification of summer hypoxia in the tidal Garonne River (SW France) simulated by a coupled hydro sedimentary-biogeochemical model

Projections for the next 50 years predict a widespread distribution of hypoxic zones in the open and coastal ocean due to environmental and global changes. The Tidal Garonne River (SW France) has already experienced few episodic hypoxic events. However, predicted future climate and demographic changes suggest that summer hypoxia could become more severe and even permanent near the city of Bordeaux in the next few decades. A 3D model, which couples hydrodynamic, sediment transport, and biogeochemical processes, is applied to assess the impact of factors submitted to global and regional climate changes on oxygenation in the turbidity maximum zone (TMZ) of the Tidal Garonne River during low-discharge periods. The model simulates an intensification of summer hypoxia with an increase in temperature, a decrease in river flow or an increase in the local population, but not with sea level rise, which has a negligible impact on dissolved oxygen. Different scenarios were tested by combining these different factors according to the regional projections for 2050 and 2100. All the simulations showed a trend toward a spatial and temporal extension of summer hypoxia that needs to be considered by local water authorities to impose management strategies to protect the ecosystem.