ALBERT

Description: Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. Here we build a global model of aerosol formation using extensive laboratory-measured nucleation rates involving sulfuric acid, ammonia, ions and organic compounds. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds in addition to sulfuric acid. A significant fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied variations in cosmic ray intensity do not significantly affect climate via nucleation in the present-day atmosphere. © 2016 American Association for the Advancement of Science.

Description: Global change has strong impacts on water resources. Analyzing these impacts in space and time requires appropriate monitoring and modeling approaches. In particular, feedbacks between land and water resources need to be better represented in modeling approaches to allow for a consistent assessment of global change impacts. We show how hydrologic models benefit from a dynamic representation of land use changes and vice versa, how land use models benefit from including hydrologic variables. Moreover, modeling global change impacts on water resources can be further advanced by coupling land use and hydrologic models. By coupling the hydrologic model SWAT (Soil and Water Assessment Tool) with the land use model CLUE-s (Conversion of Land Use and its Effects at small regional extent) the benefits of a coupled modeling approach are demonstrated. The coupling of the two models allows for a better representation of spatial dynamics and management decisions as well as for a consideration of feedback effects. With regard to research on spatio-temporal dynamics and interdisciplinary research questions it is recommended to use coupled modeling approaches to allow for a consistent and integrated assessment of global change impacts on land and water resources.

Description: Lentic small water bodies (LSWB) are widespread globally. They fulfill a variety of ecohydrological tasks and are of central importance for biodiversity in rural areas. Due to their size and location, they interact with their environment in complex ways not found in other types of water bodies. Plant protection products (PPP) and their transformation products (TP) pose a particular risk to them. However, the database of their contamination is low and inhomogeneous and transport pathways have not been sufficiently investigated so far. This study focuses on two LSWB in northern Germany that were monitored for their PSM/TP contamination and hydrological connectivity in a high-resolution measurement campaign from 10/1/20 to 10/31/21. Surface runoff, lateral flow, groundwater, drainage water, and surface water of the LSWB were analyzed for 26 PPP/TP. Based on recorded hydrological data and tracer experiments, water balances were established. Results show multiple findings of up to eight PPP/TP in all samples. In addition, several input and output pathways as well as different temporal dynamics of the various PPP/TP concentrations were identified. A pronounced interaction between the LSWB and the shallow groundwater enabling a PPP/TP exchange was observed. LSWB and shallow groundwater showed a constant and high load of the non-applied TP metazachlor-ESA. Metazachlor-ESA was measured with the highest concentrations of up to 11.66 µg L〈sup〉-1〈/sup〉 in the shallow groundwater and loads of up to 3.12 g in a single inflow per month. For one of the LSWB, a drainage system was a major input pathway for PPP/TP.