Person: Leujak, Wera
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Veröffentlichung Wasserwirtschaft in Deutschland(2017) Arle, Jens; Bartel, Hartmut; Baumgarten, Corinna; Bertram, Andreas; Blondzik, Katrin; Brandt, Simone; Brauer, Frank; Claussen, Ulrich; Damian, Hans-Peter; Dieter, Daniela; Ginzky, Harald; Grimm, Sabine; Helmecke, Manuela; Hofmeier, Katja; Hofmeier, Maximilian; Hülsmann, Wulff; Kirschbaum, Bernd; Knobloch, Tobias; Koppe, Katharina; Koschorreck, Jan; Krakau, Manuela; Leujak, Wera; Mathan, Cindy; Mohaupt, Volker; Naumann, Stephan; Pickl, Christina; Rapp, Thomas; Rechenberg, Jörg; Deutschland. Umweltbundesamt. Abteilung II.2-Wasser und BodenDie Broschüre Wasserwirtschaft in Deutschland bietet einen umfassenden Überblick über die Grundlagen, Belastungen und Maßnahmen der deutschen Wasserwirtschaft und präsentiert wesentliche Fakten und aktuelle Daten rund um den Zustand unserer Gewässer, Gewässerschutz sowie Wasserversorgung und Ń entsorgung. Mit dieser Broschüre bieten wir interessierten Leserinnen und Lesern sowie der Fachöffentlichkeit ein Kompendium an Informationen und stellen Studierenden sowie Medienschaffenden eine zuverlässige Grundlage für wissenschaftliche Arbeiten und die Berichterstattung in diesem Themenbereich bereit. Quelle: https://www.umweltbundesamt.de/Veröffentlichung Eutrophication, contaminants, litter and climate change(2022) Busse, Lilian; Claussen, Ulrich; Krakau, Manuela; Künitzer, Anita; Leujak, Wera; Weiß, Andrea; Werner, StefanieDie Ostsee ist nach wie vor von zahlreichen Belastungen betroffen. Es sind weitere Anstrengungen erforderlich, um diese zu reduzieren und gesunde und widerstandsfähige Meeresökosysteme sowie ihre nachhaltige Nutzung zu erreichen. Dies kann nur durch die Zusammenarbeit der Ostseeanrainerstaaten und eine starke regionale Governance erzielt werden. Der Ostseeaktionsplan ist das vielversprechendste Instrument, diese Bemühungen für die Ostsee umzusetzen und die globalen Ziele des Meeresschutzes voranzubringen. ©2022 Walter de Gruyter GmbHVeröffentlichung Waters in Germany(2017) Arle, Jens; Blondzik, Katrin; Claussen, Ulrich; Duffek, Anja; Grimm, Sabine; Hilliges, Falk; Kirschbaum, Bernd; Kirst, Ingo; Koch, Dietmar; Koschorreck, Jan; Lepom, Peter; Leujak, Wera; Mohaupt, Volker; Naumann, Stephan; Rechenberg, Jörg; Schilling, Petra; Ullrich, Antje; Wellmitz, Jörg; Werner, Stefanie; Wolter, Rüdiger; Deutschland. UmweltbundesamtVeröffentlichung Eutrophication assessment in the transit area German Bight (North Sea) 2006-2014 - Stagnation and limitations(2018) Brockmann, Uwe; Topcu, Dilek H.; Leujak, Wera; Schütt, M.The eutrophication status of the German Bight (North Sea) has been assessed the third time since 1998 according to the OSPAR-Comprehensive Procedure between 2006 and 2014. Since the 1980s nutrient discharges and atmospheric nitrogen deposition had declined significantly but chlorophyll a and nutrient concentrations remained above assessment levels inshore and in inner coastal waters, reflecting continuing eutrophication. Recently local river discharges stagnated or increased again and total nitrogen remained above a reduction target of 200 myM. Most nutrients and conversion products were imported by a coastal current, passing the German Bight. Organic matter was trapped in offshore bottom waters in the ancient Elbe valley, causing repeated annual oxygen minima (<6 mg/L) and a classification as Problem Area. Effects of national reduction measures are limited in the transit area German Bight because improvements in open coastal waters require international efforts, based on comprehensive analyses. © 2018 Elsevier Ltd. All rights reserved.Veröffentlichung Water Resource Management in Germany(2017) Arle, Jens; Bartel, Hartmut; Baumgarten, Corinna; Bertram, Andreas; Blondzik, Katrin; Brandt, Simone; Brauer, Frank; Claussen, Ulrich; Damian, Hans-Peter; Dieter, Daniela; Ginzky, Harald; Grimm, Sabine; Helmecke, Manuela; Hofmeier, Katja; Hofmeier, Maximilian; Hülsmann, Wulff; Kirschbaum, Bernd; Knobloch, Tobias; Koppe, Katharina; Koschorreck, Jan; Krakau, Manuela; Leujak, Wera; Mathan, Cindy; Mohaupt, Volker; Naumann, Stephan; Pickl, Christina; Rapp, Thomas; Rechenberg, Jörg; Deutschland. Umweltbundesamt. Abteilung II.2-Wasser und Boden; Deutschland. Bundesministerium für Umwelt, Naturschutz und nukleare SicherheitVeröffentlichung Long-term field study of the behaviour of Xenopus laevis (Pipidae) in a small dam(2022) Elepfandt, Andreas; Gutsche, Alexander; Fischer, Werner J; Leujak, WeraA study of the behaviour of Xenopus laevis in a small dam in South Africa was continued annually from 1992 until 1999. All individuals were tagged. The annual number of frogs varied between 22 and 109 by migration. The sex ratio remained balanced. Most subadults stayed for just one season, whereas half of the adults remained longer. Some individuals reappeared after one or more years of absence. Within a season, male activity was concentrated in series of nights between quiet periods. Higher population density did not result in more territorial, stationary, or roaming males, or more fighting, but mainly in a higher number of inactive males. Fighting was intense, however, at extreme low water in 1995. Territorial males might maintain their territory in subsequent years. The size of individuals did not differ between behavioural types and males of any behaviour could mate successfully. The rare matings aggregated in adjacent nights at peak calling. Female approach to males was not seen, but playback in silent nights caused some females to linger near the loudspeaker. Females that experienced no amplexus during our observations were found significantly more in the shallow areas of the dam where sound did not enter. For mating, females accepted only males larger than 65 mm SVL and repelled all smaller ones. Mating was not size assortative. In both sexes, maturation took years of gradual development before successful mating. © 2021 Herpetological Association of Africa.Veröffentlichung Nutrient criteria for surface waters under the European Water Framework Directive: Current state-of-the-art, challenges and future outlook(2019) Poikane, Sandra; Claussen, Ulrich; Kelly, Martyn G.; Salas Herrero, Fuensanta; Leujak, WeraThe aim of European water policy is to achieve good ecological status in all rivers, lakes, coastal and transitional waters by 2027. Currently, more than half of water bodies are in a degraded condition and nutrient enrichment is one of the main culprits. Therefore, there is a pressing need to establish reliable and comparable nutrient criteria that are consistent with good ecological status. This paper highlights the wide range of nutrient criteria currently in use by Member States of the European Union to support good ecological status and goes on to suggest that inappropriate criteria may be hindering the achievement of good status. Along with a comprehensive overview of nutrient criteria, we provide a critical analysis of the threshold concentrations and approaches by which these are set. We identify four essential issues: (1) Different nutrients (nitrogen and/or phosphorus) are used for different water categories in different countries. (2) The use of different nutrient fractions (total, dissolved inorganic) and statistical summary metrics (e.g., mean, percentiles, seasonal, annual) currently hampers comparability between countries, particularly for rivers, transitional and coastal waters. (3) Wide ranges in nutrient threshold values within shared water body types, in some cases showing more than a 10-fold difference in concentrations. (4) Different approaches used to set threshold nutrient concentrations to define the boundary between "good" and "moderate" ecological status. Expert judgement-based methods resulted in significantly higher (less stringent) good-moderate threshold values compared with data-driven approaches, highlighting the importance of consistent and rigorous approaches to criteria setting. We suggest that further development of nutrient criteria should be based on relationships between ecological status and nutrient concentrations, taking into account the need for comparability between different water categories, water body types within these categories, and countries. © 2019 The Authors. Published by Elsevier B.V.Veröffentlichung Gewässer in Deutschland(2017) Arle, Jens; Blondzik, Katrin; Claussen, Ulrich; Duffek, Anja; Grimm, Sabine; Hilliges, Falk; Kirschbaum, Bernd; Kirst, Ingo; Koch, Dietmar; Koschorreck, Jan; Lepom, Peter; Leujak, Wera; Mohaupt, Volker; Naumann, Stephan; Rechenberg, Jörg; Schilling, Petra; Ullrich, Antje; Wellmitz, Jörg; Werner, Stefanie; Wolter, Rüdiger; Deutschland. Umweltbundesamt