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A nanoparticular p-n junction was realized by a field-assisted sintering process, using p-type and n-type doped silicon nanoparticles. A spatially resolved Seebeck microscan showed a broad transition from the positively doped to the negatively doped range. Overshoots on both sides are characteristic for the transition. Despite the tip size being much larger than the mean particle size, information about the dopant distribution between the particles is deduced from modeling the measured data under different assumptions, including the limited spatial resolution of the tip. The best match between measured and modeled data is achieved by the idea of doping compensation, due to the sintering process. Due to a short time at high temperature during the field-assisted sintering process, solid state diffusion is too slow to be solely responsible for the observed compensation of donors and acceptors over a wide range. Therefore, these measurements support a densification mechanism based on (partial) melting and recrystallization. [ABSTRACT FROM AUTHOR]

Surface waters, especially in densely populated areas, are facing multiple anthropogenic pressures. Micro pollutants are of growing concern. Improved analytical methods are used to focus on substances like ICM with a (high) potential of hazardous effects against water organisms or the water quality in general ICM are essential for instance in computer tomographic examinations in medical facilities. Discharge of ICM to the sewer system occurs via human urine excretions. Common waste water treatment plants do not eliminate these substances completely. Therefore, increasing concentrations are found in the rivers worldwide. The project MERK'MAL explored a potentially cost-effective measure to reduce ICM in the River Ruhr, located in Germany, North Rhine-Westphalia. The results from this pilot study show that urine bags are an effective measure to reduce ICM concentrations. During the urine collection with bags measurements of ICM concentrations have shown a reduction, compared to the baseline concentration that was measured at the same sampling point in the effluent of the corresponding waste water treatment plant. The ICM reduction ranged between 20 and 34% for the mean values and between 7 and 33% for the median value. Additional payment equivalent costs per examination with ICM are approx. 3.36 €, full costs including imputed costs are expected in a cost range of 5.38 € to 6.09 € per examination. The extension of the study is envisioned, helping to sustainably enhance water quality in the River Ruhr in terms of ICM concentrations., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In the year 2010, effluents from 90 European wastewater treatment plants (WWTPs) were analyzed for 156 polar organic chemical contaminants. The analyses were complemented by effect-based monitoring approaches aiming at estrogenicity and dioxin-like toxicity analyzed by in vitro reporter gene bioassays, and yeast and diatom culture acute toxicity optical bioassays. Analyses of organic substances were performed by solid-phase extraction (SPE) or liquid-liquid extraction (LLE) followed by liquid chromatography tandem mass spectrometry (LC-MS-MS) or gas chromatography high-resolution mass spectrometry (GC-HRMS). Target microcontaminants were pharmaceuticals and personal care products (PPCPs), veterinary (antibiotic) drugs, perfluoroalkyl substances (PFASs), organophosphate ester flame retardants, pesticides (and some metabolites), industrial chemicals such as benzotriazoles (corrosion inhibitors), iodinated x-ray contrast agents, and gadolinium magnetic resonance imaging agents; in addition biological endpoints were measured. The obtained results show the presence of 125 substances (80% of the target compounds) in European wastewater effluents, in concentrations ranging from low nanograms to milligrams per liter. These results allow for an estimation to be made of a European median level for the chemicals investigated in WWTP effluents. The most relevant compounds in the effluent waters with the highest median concentration levels were the artificial sweeteners acesulfame and sucralose, benzotriazoles (corrosion inhibitors), several organophosphate ester flame retardants and plasticizers (e.g. tris(2-chloroisopropyl)phosphate; TCPP), pharmaceutical compounds such as carbamazepine, tramadol, telmisartan, venlafaxine, irbesartan, fluconazole, oxazepam, fexofenadine, diclofenac, citalopram, codeine, bisoprolol, eprosartan, the antibiotics trimethoprim, ciprofloxacine, sulfamethoxazole, and clindamycine, the insect repellent N,N'-diethyltoluamide (DEET), the pesticides MCPA and mecoprop, perfluoroalkyl substances (such as PFOS and PFOA), caffeine, and gadolinium., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Many rivers and streams worldwide are impacted by pharmaceuticals originating from sewage. The hyporheic zone underlying streams is often regarded as reactive bioreactor with the potential for eliminating such sewage-born micropollutants. The present study aims at checking the elimination potential and analyzing the coupling of hydrodynamics, biogeochemistry and micropollutant processing. To this end, two sites at the lowland stream Erpe, which receives a high sewage burden, were equipped and sampled with nested piezometers. From temperature depth profiles we determined that at one of the sites infiltration of surface water into the aquifer occurs while exfiltration dominates at the other site. Biogeochemical data reveal intense mineralization processes and strictly anoxic conditions in the streambed sediments at both sites. Concentrations of the pharmaceuticals indomethacin, diclofenac, ibuprofen, bezafibrate, ketoprofen, naproxen and clofibric acid were high in the surface water and also in the subsurface at the infiltrating site. The evaluation of the depth profiles indicates some attenuation but due to varying surface water composition the evaluation of subsurface processes is quite complex. Borate and non-geogenic gadolinium were measured as conservative wastewater indicators. To eliminate the influence of fluctuating sewage proportions in the surface water, micropollutant concentrations are related to these indicators. The indicators can cope with different dilutions of the sewage but not with temporally varying sewage composition., (Copyright © 2011 Elsevier B.V. All rights reserved.)

This study provides the first pan-European reconnaissance of the occurrence of polar organic persistent pollutants in European ground water. In total, 164 individual ground-water samples from 23 European Countries were collected and analysed (among others) for 59 selected organic compounds, comprising pharmaceuticals, antibiotics, pesticides (and their transformation products), perfluorinated acids (PFAs), benzotriazoles, hormones, alkylphenolics (endocrine disrupters), Caffeine, Diethyltoluamide (DEET), and Triclosan. The most relevant compounds in terms of frequency of detection and maximum concentrations detected were DEET (84%; 454 ng/L), Caffeine (83%; 189 ng/L), PFOA (66%; 39 ng/L), Atrazine (56%; 253 ng/L), Desethylatrazine (55%; 487 ng/L), 1H-Benzotriazole (53%; 1032 ng/L), Methylbenzotriazole (52%; 516 ng/L), Desethylterbutylazine (49%; 266 ng/L), PFOS (48%, 135 ng/L), Simazine (43%; 127 ng/L), Carbamazepine (42%; 390 ng/L), nonylphenoxy acetic acid (NPE(1)C) (42%; 11 microg/L), Bisphenol A (40%; 2.3 microg/L), PFHxS (35%; 19 ng/L), Terbutylazine (34%; 716 ng/L), Bentazone (32%; 11 microg/L), Propazine (32%; 25 ng/L), PFHpA (30%; 21 ng/L), 2,4-Dinitrophenol (29%; 122 ng/L), Diuron (29%; 279 ng/L), and Sulfamethoxazole (24%; 38 ng/L). The chemicals which were detected most frequently above the European ground water quality standard for pesticides of 0.1 microg/L were Chloridazon-desphenyl (26 samples), NPE(1)C (20), Bisphenol A (12), Benzotriazole (8), N,N'-Dimethylsulfamid (DMS) (8), Desethylatrazine (6), Nonylphenol (6), Chloridazon-methyldesphenyl (6), Methylbenzotriazole (5), Carbamazepine (4), and Bentazone (4). However, only 1.7% of all single analytical measurements (in total 8000) were above this threshold value of 0.1 microg/L; 7.3% were > than 10 ng/L., (Copyright 2010 Elsevier Ltd. All rights reserved.)

There is strong evidence of continuously increasing contamination of soils with platinum group elements (PGE), in particular with platinum (Pt) from vehicle exhaust catalysts in roadside soils. However, knowledge about the effects of Pt contamination on soil processes is very limited. The objective of this study was to investigate whether the contamination of soils with Pt at realistic environmental levels leads to observable adverse effects on selected indicator parameters of the carbon and nitrogen turnover in soils. Incubation experiments with artificially contaminated soils and solutions containing dissolved organic matter (DOM) were carried out by the use of milled material from a Pt-containing vehicle exhaust catalyst. Interaction of the catalyst material with the soil resulted in a mobilization of Pt into the dissolved phase reaching up to 0.1% of the added Pt. The amount of Pt mobilization seemed to be mainly driven by the pH of the soil. Mineralization of carbon and nitrogen did not reveal any significant adverse effect of the Pt addition as compared to the control samples. Future studies dealing with Pt effects on soil processes should focus on environmental conditions favoring Pt mobilization, e.g. such as very low pH values or large concentrations of DOM.

Organotin compounds (OTC) are highly toxic pollutants and have been mostly investigated so far in aquatic systems and sediments. The concentrations and fluxes of different organotin compounds, including methyl-, butyl-, and octyltin species in precipitation and fog were investigated in a forested catchment in NE Bavaria, Germany. Contents, along with the vertical distribution and storages in two upland and two wetland soils were determined. During the 1-year monitoring, the OTC concentrations in bulk deposition, throughfall and fog ranged from 1 ng Sn l(-1) to several ten ng Sn l(-1), but never over 200 ng Sn l(-1). The OTC concentrations in fog were generally higher than in throughfall and bulk deposition. Mono-substituted species were the dominant Sn species in precipitation (up to 190 ng Sn l(-1)) equaling a flux of up to 70 mg Sn ha(-1) a(-1). In upland soils, OTC contents peaked in the forest floor (up to 30 ng Sn g(-1)) and decreased sharply with the depth. In wetland soils, OTC had slightly higher contents in the upper horizons. The dominance of mono-substituted species in precipitation is well reflected in the contents and storages of OTC in both upland and wetland soils. The ratios of OTC soil storages to the annual throughfall flux ranged from 20 to 600 years. These high ratios are probably due to high stability and low mobility of OTC in soils. No evidence was found for methylation of tin in the wetland soils. In comparison with sediments, concentrations and contents of organotin in forest soils are considerably lower, and the dominant species are less toxic. It is concluded that forested soils may act as sinks for OTC deposited from the atmosphere.

Mercury (Hg) and methylmercury (CH3Hg+) are global pollutants, but little information is available on rates of atmospheric input, distribution and mobility in soils and catchments of central Europe. The objectives of this study were to investigate input and output fluxes of these compounds in a deciduous and a coniferous catchment in NE Bavaria (Germany), and to estimate pools and mobility of total Hg (Hgtot) and CH3Hg+ at the catchment scale. Bulk precipitation, throughfall, litterfall and runoff were collected biweekly from April 1998 to April 1999. Several soil profiles were sampled to estimate pools of Hg compounds in the catchments. In both catchments highest contents of Hgtot were found in the Oa layer of the forest floor (up to 500 ng g(-1)) and the soil storage of Hgtot calculated for a soil depth of 60 cm was approximately 890 g ha(-1) in the coniferous and 190 g ha(-1) in the deciduous catchment. Highest contents of CH3Hg+ in upland soils were observed in the Oi layer of the forest floor, and soil storage of CH3Hg+ was 4.35 g ha(-1) in the coniferous and 0.59 g ha(-1) in the deciduous catchment. The annual total deposition of Hgtot (total deposition not measured directly but calculated from throughfall and litterfall) was 541 mg ha(-1) year(-1) in the coniferous and 618 mg ha(-1) year(-1) in the deciduous catchment. Total deposition rates of CH3Hg+ were 3.5 and 2.6 mg ha(-1) year(-1). The contribution of litterfall to the total deposition of Hgtot and CH3Hg+ was 55% in the deciduous catchment. In the coniferous catchment, the contribution of litterfall to total deposition was only 29% for Hgtot, but 55% for CH3Hg+. By far the largest proportion of the deposited CH3Hg+ and Hgtot remained in the catchments (85% in the coniferous, 95% in the deciduous). As compared to remote Swedish catchments, deposition and output via runoff of Hgtot, were higher, but deposition and output of CH3Hg+ were lower in our catchments. In contrast to other studies, the annual budget revealed no differences in the mobility between the two species at the catchment scale. However, temporal patterns of the runoff fluxes and converse gradients of CH3Hg+ and Hgtot contents in the forest floor indicated differences in mobility on shorter time scales.