Open Source Geospatial Applications to support River Basin Management in Kharaa River Basin, Mongolia

An open access geoportal, developed using open source technologies, delivers a comprehensive overview of all geodata available for the Kharaa River Basin in Mongolia. The Water Quality Monitoring Database is made available in PostgreSQL/PostGIS format and embedded in the geoportal. Web maps in the Geoportal can be linked to monitoring data using interactive queries to the Water Quality Database enabling water managers to create thematic maps on demand for the development of a comprehensive river basin management plan for the Kharaa River Basin

Citizen science for assessing pesticide impacts in agricultural streams

The majority of central European streams are in poor ecological condition. Pesticide inputs from terrestrial habitats present a key threat to sensitive insects in streams. Both standardized stream monitoring data and societal support are needed to conserve and restore freshwater habitats. Citizen science (CS) offers potential to complement international freshwater monitoring while it is often viewed critically due to concerns about data accuracy. Here, we developed a CS program based on the Water Framework Directive that enables citizen scientists to provide data on stream hydromorphology, physicochemical status and benthic macroinvertebrates to apply the trait-based bio-indicator SPEARpesticides for pesticide exposure. We compared CS monitoring data with professional data across 28 central German stream sites and could show that both CS and professional monitoring identified a similar average proportion of pesticide-sensitive macroinvertebrate taxa per stream site (20 %). CS data were highly correlated to the professional data for both stream hydromorphology and SPEARpesticides (r = 0.72 and 0.76). To assess the extent to which CS macroinvertebrate data can indicate pesticide exposure, we tested the relationship of CS generated SPEARpesticides values and measured pesticide concentrations at 21 stream sites, and found a fair correlation similar to professional results. We conclude that given appropriate training and support, citizen scientists can generate valid data on the ecological status and pesticide contamination of streams. By complementing official monitoring, data from well-managed CS programs can advance freshwater science and enhance the implementation of freshwater conservation goals

Controllable orbital angular momentum monopoles in chiral topological semimetals

The emerging field of orbitronics aims at generating and controlling currents of electronic orbital angular momentum (OAM) for information processing. Structurally chiral topological crystals could be particularly suitable orbitronic materials because they have been predicted to host topological band degeneracies in reciprocal space that are monopoles of OAM. Around such a monopole, the OAM is locked isotopically parallel or antiparallel to the direction of the electron's momentum, which could be used to generate large and controllable OAM currents. However, OAM monopoles have not yet been directly observed in chiral crystals, and no handle to control their polarity has been discovered. Here, we use circular dichroism in angle-resolved photoelectron spectroscopy (CD-ARPES) to image OAM monopoles in the chiral topological semimetals PtGa and PdGa. Moreover, we also demonstrate that the polarity of the monopole can be controlled via the structural handedness of the host crystal by imaging OAM monopoles and anti-monopoles in the two enantiomers of PdGa, respectively. For most photon energies used in our study, we observe a sign change in the CD-ARPES spectrum when comparing positive and negative momenta along the light direction near the topological degeneracy. This is consistent with the conventional view that CD-ARPES measures the projection of the OAM monopole along the photon momentum. For some photon energies, however, this sign change disappears, which can be understood from our numerical simulations as the interference of polar atomic OAM contributions, consistent with the presence of OAM monopoles. Our results highlight the potential of chiral crystals for orbitronic device applications, and our methodology could enable the discovery of even more complicated nodal OAM textures that could be exploited for orbitronics.Comment: 16 pages, 8 figure

Charge state-dependent symmetry breaking of atomic defects in transition metal dichalcogenides

The functionality of atomic quantum emitters is intrinsically linked to their host lattice coordination. Structural distortions that spontaneously break the lattice symmetry strongly impact their optical emission properties and spin-photon interface. Here we report on the direct imaging of charge state-dependent symmetry breaking of two prototypical atomic quantum emitters in mono- and bilayer MoS2 by scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM). By changing the built-in substrate chemical potential, different charge states of sulfur vacancies (VacS) and substitutional rhenium dopants (ReMo) can be stabilized. Vac as well as Re and Re exhibit local lattice distortions and symmetry-broken defect orbitals attributed to a Jahn-Teller effect (JTE) and pseudo-JTE, respectively. By mapping the electronic and geometric structure of single point defects, we disentangle the effects of spatial averaging, charge multistability, configurational dynamics, and external perturbations that often mask the presence of local symmetry breaking

Metadata describing the Kharaa Yeröö River Basin Water Quality Database

n the framework of the BMBF funded project on Integrated Water Resources Management in Central Asia (Model region Mongolia, MOMO project, www.iwrm-momo.de) the objectives focused on supplementing, validating and extending the existing surveillance monitoring to the entire river basin for the time series 2006-2017. The MOMO monitoring programme was set up in order to observe seasonal variation in various water quality parameters along the main river course and its tributaries. A detailed sampling survey was carried out along the Kharaa River in the spring, summer and autumn of 2006 to 2017, extending from the headwaters in the Khentii Mountains to the outlet of the river basin. An additional continuous monthly monitoring programme for surface water quality was carried out upstream (Deed Guur) and downstream of Darkhan city (Buren Tolgoi) including the outlet of WWTP Darkhan in the time between 2007 and 2017. This strategy provides information for the efficient and effective design of future monitoring programmes with a focus on operational or investigative issues. The types of water sampling programmes included initial surveys as well as investigative and operational monitoring, point-source characterization, intensive surveys, fixed-station-network monitoring, groundwater monitoring, and special surveys involving chemical and biological monitoring. The water analyses have a focus on nutrients, heavy metals and metalloids, chloride, boron and the main physical water parameters. The dataset comprises also fluvial sediment analyses on heavy metals. In addition in 2017 a special hygienic monitoring (total coliforms, E. coli and fecal coliforms) has been carried out and was included in this database