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The purpose of this study was to determine the nitrogen (N) deposition in a mire of the German National Park Hochharz Mountains in regard to different input pathways of open area and forest stand deposition. High N deposition rates strongly affect the development and growth of mires in general. For determination of the open area N deposition two methods were applied: the bulk deposition method and the Integral Total Nitrogen Input (ITNI) method. This method is based on the 15N isotope dilution technique and was adapted at this study to evaluate its applicability for natural ecosystems as well as to compare with the traditional bulk method. The forest stand deposition included canopy throughfall, stemflow and fog was measured by means of bulk collectors. On the test site, bulk deposition measurements showed an input of 27 kg N ha− 1 yr− 1 in the open area and 47 kg N ha− 1 yr− 1 in the forest stand. The higher N input in the forest stand is caused by interception of fog by the canopy. N concentrations in fog were up to more than six times higher than in rain. The ITNI system yielded a total N deposition of 30 kg N ha− 1 yr− 1 on average in the open area. The small differences between the two simultaneously applied measuring techniques were caused by a minimum biomass development of the autochthonous plant Calamagrostis villosa in the ITNI system. With increasing biomass production the influence of plants on the atmospheric N input also increased. It can be concluded that the ITNI system is beneficial for the application in a natural ecosystem when using more robust and biomass producing plants. The measured atmospheric N deposition exceeds the critical load for nutrient poor mires and represents therefore a potential risk for the continuity of this ecosystem. [ABSTRACT FROM AUTHOR]

Pesticide inputs into surface waters may cause harmful effects on aquatic life communities and substantially contribute to environmental pollution. The present study aimed at evaluating the input pathways in the Querne/Weida catchment (central Germany) to efficiently target mitigation measures of pesticide losses. Relevant pesticide substances were measured in surface waters in agricultural and urban surroundings and in soil samples within the catchment area. Pesticides application data from farmers were analyzed. Additionally, batch tests were performed to determine sorption and degradation of relevant pesticides for site specific soil properties. Frequency of detection, number of pesticides and maximum concentrations were much higher in the surface water samples in mainly urban surroundings compared to those in agricultural surrounding. The most frequently detected substances were glyphosate, AMPA, diflufenican and tebuconazole in surface water samples and diflufenican, boscalid, tebuconazole and epoxiconazole in the topsoil samples. Glyphosate and AMPA contributed to the highest concentrations in surface water samples (max. 58 μg L -1 ) and soil samples (max. 0.19 mg kg -1 ). In most cases, pesticide detections in surface water and soil were not consistent with application data from farmers, indicating that urban sources may affect water quality in the catchment area substantially. However, it was observed that pesticide substances remain in the soil over a long time supported by sorption on the soil matrix. Therefore, delayed inputs into surface waters could be suspected. For the implementation of reduction measures, both urban and agricultural sources should be considered. Novel findings of the study: pesticide detections were not consistent with application data from farmers, urban sources contributed substantially to pesticide pollution of surface waters., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Denitrification is well known being the most important nitrate-consuming process in water-logged peat soils, whereby the intermediate compound nitrous oxide (N(2)O) and the end product dinitrogen (N(2)) are ultimately released. The present study was aimed at evaluating the release of these gases (due to denitrification) from a nutrient-poor transition bog ecosystem under drained and three differently rewetted conditions at the field scale using a (15)N-tracer approach ([(15)N]nitrate application, 30 kg N ha(-1)) and a common closed-chamber technique. The drained site is characterized by a constant water table (WT) of -30 cm (here referred to as D30), while rewetted sites represent a constant WT of -15 cm, a constant WT of 0 cm (i.e. waterlogged), and an initial WT of 0 cm (which decreased slightly during the experiment), respectively, (here referred to as R15, R0, and R0(d), respectively). The highest N(2)O emissions were observed at D30 (291 µg N(2)O-N m(-2) h(-1)) as well as at R0d (665 µg N(2)O-N m(-2) h(-1)). At the rewetted peat sites with a constant WT (i.e. R15 and R0), considerably lower N2O emissions were observed (maximal 37 µg N(2)O-N m(-2) h(-1)). Concerning N(2) only at the initially water-logged peat site R0d considerable release rates (up to 3110 µg N(2)-N m(-2) h(-1)) were observed, while under drained conditions (D30) no N(2) emission and under rewetted conditions with a constant WT (R15 and R0) significantly lower N(2) release rates (maximal 668 µg N(2)-N m(-2) h(-1)) could be detected. In addition, it has been found that natural WT fluctuations at rewetted peat sites, in particular a rapid drop down of the WT, can induce high emission rates for both N(2)O and N(2).