Managed aquifer recharge is gaining importance as a practice to bank and treat surface water for drinking water production. Neon (Ne) concentrations were analysed at four different recharge sites in and near Berlin, where groundwater is recharged directly from surface water courses, either by near-natural bank filtration, induced bank filtration or engineered basin recharge. Neon concentrations in excess of saturation (DNe) were used to identify excess air in the infiltrates. Excess air concentrations were around saturation at the near-natural bank filtration site, where river water infiltrates through a permeable river bed into a confined aquifer under completely saturated conditions. At two induced unconfined bank filtration sites, samples generally contained excess air (up to 60% DNe). Highest excess air concentrations (up to 81% DNe) were encountered at the engineered basin recharge site. The degree of water table fluctuations, the water saturation of the sediments in the infiltration zone and the presence of a confining layer affect the formation of excess air. Excess air can only be used to trace bank filtrate or artificially recharged water in a setting where the ambient groundwater in the near vicinity of production wells is not affected by large water-table fluctuations. Nevertheless, excess air concentrations provide valuable additional information on the type of recharge (saturated or unsaturated, degree of water table fluctuations).

Odours emerging from sewage networks are unpleasant, can cause health impacts on sewer workers and impair public perception of the operator companies. Corrosion is one of the causes for the cost of repairs for damages to wastewater systems in the public sewage network, which are rising extremely [DWA, 2004]. Both phenomena can have their origin in biogenic acid corrosion that is illustrated in this report. The Kompetenzzentrum Wasser Berlin (KWB) commissioned the Technical University Berlin and the Material Testing Institute of Berlin-Brandenburg to give a report on: • State of the art on control systems for odours and corrosion problems in sewer networks, (i) State of the art on sensor technologies for water, gas and corrosion parameters to follow corrosion and H2S production, (ii) Investigation on the feasibility to develop a three-phase model to predict the mass transfer of H2S from water to the gas phase and to the wall of the pipe through the biofilm and (iii) Elaboration of a draft of the functional and technical specifications for a sewer network pilot plant.

Tropical cyanobacteria in German waters: Causes and consequences - Toxic cyanobacteria of tropical origin have spread to water bodies in northern Germany. Here their population size is determined by the onset of germination: the earlier the time of germination, the larger the summer population. Climate-related early increase in water temperatures over the course of the years has promoted their spreading to temperate regions. Toxins known from these species in tropical regions were also found in German lakes. Surprisingly, these toxins are not produced by the invaders but by native species. Thus, the invasion have drawn our attention to an old problem. However, the invaders itself potentially also poses a health risk in German lakes since they produce other – so far unidentified – toxic substances.

The study “Trace pollutants in combined sewer overflows” provides an overview on the input of trace substances (organic or inorganic trace substances) to surface waters during combined sewer overflows (CSO). The study outlines substance pathways, types of substances, expected loads as well as possible impacts on the receiving water. The study shall aid the discussion and further handling of trace substances within the project Monitor-1, which is currently carried out at the Berlin Centre of Competence for Water (KWB). The study has identified more than 300 substances, which could reach the Berlin surface water bodies via CSO. Moreover, it is assumed that there is a large number of substances and metabolites, which are still unknown. Sewage-related substances in combined sewers can stem from: household products (e.g. surfactants from cleaning agents), leaching (e.g. amines from textile colours or Bisphenol A from plastic coatings), wash-off of cosmetic products (e.g. Benzophenone-3 from sunblocks) or health lotions, excretion of ingested products (e.g. the pain killer Diclofenac). Stormwater-related substances in combined sewers can stem from abrasion from car and railway traffic (e.g. cadmium from break lining abrasion), erosion of building materials (e.g. copper from eaves gutters), application (e.g. glyphosate for weed control on pavements) or atmospheric deposition (e.g. polychlorinated dibenzofurans from exhaust fumes). In the framework of this study available substance data was assembled, containing: general information like synonyms and CAS-No., chemical properties, elimination rate in wastewater treatment plant (WWTP), observed concentrations in surface waters and toxicity. A complete list of the substances as well as selected substance properties is attached in table A6 (Appendix). Some of these substances can be used as tracers to distinguish different pollution pathways to surface waters. Suitable indicators should enter surface waters mainly via one pathway, their half-life in surface waters should be sufficiently long, concentrations should show no seasonal fluctuations and they should be well-measurable. For instance, caffeine is a good indicator for inflows of untreated sewage via CSO, as it is very well degraded in WWTP. As an indicator for treated sewage the almost nondegradable anti-epileptic Carbamazepine could be used. Finally, polycyclic aromatic hydrocarbons (PAH) could be used as indicator for stormwater-related pollution. In road traffic, PAHs result from incomplete combustion processes, adsorb on atmospheric particles, deposit on the surface and are washed off by rainfall runoff. In this study the relevance of the path “CSO” for trace substance emissions from the Berlin wastewater system in comparison to the other paths (storm drainage and WWTP) was assessed. Therefore, a simple balance of the fraction of CSO in total emissions to the Berlin surface waters was carried out. The balance was based on the annual volumes of WWTP effluents, storm drainage and CSO. Due to a lack in substancespecific measurement information the balance was calculated dependent on the elimination rate of substances in WWTPs. Based on the resulting figures A, B, C, D and E the fraction of CSO in total loads to the Berlin surface waters can be assessed for each substance with known elimination rate in WWTPs. In the study we distinguished between: (i) sewage related substances / stormwater related substances, (ii) balance area „Berlin total“ (5 WWTPs with 622,000 m³/d, 97 km2 combined sewer system, 231 km2 storm drainage system) / balance area „Berlin city centre“ (60% of the WWTP Münchehofe with 39,000 m³/d, 83 km2 combined sewer system, 112 km2 storm drainage system) and (iii) total annual loads / event based loads.

In the rural and semi-rural environment many sources of contamination may impact surface water quality. In addition to nutrients from agricultural activities, contaminants occurring at low concentration so-called trace contaminants are a growing issue for water quality. To address this issue and investigate mitigation measures, the Berlin Centre of Competence for Water (KompetenzZentrum Wasser Berlin) developed a collaborative research project called Aquisafe, in association with the Indiana University – Perdue University Indianapolis (IUPUI), the German Federal Agency for the Environment “Umweltbundesamt” (UBA) and Veolia Water. The project aims at investigating mitigation zones such as constructed wetlands or riparian zones to improve the quality of surface water with respect to diffuse pollution. Before using models and conducting field experiments, the first part of the project is an extensive analysis of the nature, occurrence, and risks of source water contamination in rural and semi-rural areas. This is the subject of the poster. The objectives of this first part of the project are (i) to provide background information on surface water and its use in Europe, particularly regarding drinking water supply, (ii) to investigate the characteristics of the families of pollutants that are potentially of interest, and finally (iii) to select the most relevant trace contaminants to be investigated in future field experiments. To reach these objectives, an extensive literature review was carried out, using different criteria to select the relevant families of pollutants and then the individual substances. The screening process is currently in progress and includes a collection of substance characteristics that will be used for subsequent selection, such as toxicity or persistence in the environment. Key figures and information were collected concerning the nature, use and vulnerability of surface water in Europe that provides 70% of total water abstraction (drinking water, industry and agriculture) in Europe. The main pollutant families of interest for the screening process were the following: pesticides used in agriculture (e.g. glyphosate or isoproturon), pollutants coming from the spreading of animal waste on land (e.g. veterinary pharmaceuticals or hormones), pollutants coming from the spreading of sludge from wastewater treatment plants (e.g. heavy metals or hormones), pollutants from natural areas (e.g. flame retardants in forests), and pollutants from transportation networks (e.g. heavy metals from vehicles). Consequently in a rural or semi-rural area, the land use in the watershed plays a key role in the selection and assessment of priority pollutants coming from diffuse sources and entering surface waters. The work is still in progress concerning the review of pollutant families, and will lead to the final screening at substance level, providing a list of key contaminants for the other work packages within the Aquisafe project. Eventually, corresponding data for the same issues in the United States will be added and provide a comparison between the two continents.

The Aquisafe project assesses the effectiveness of natural mitigation zones in reducing diffuse pollution to surface waters. In one case study on a constructed wetland in agriculturally dominated Western France, nitrate concentrations from drainage inflows to a small river decreased up to tenfold on the way through an intermediary constructed wetland. However, only ~30 % of the total N-load is retained in the wetland, whereas ~70 % enters the river directly during high flow events as a result of low soil permeability. The study underlines the importance of flow paths and infiltration for nitrate removal in natural or constructed wetlands, which is often neglected in practice.

The Aquisafe project is a cooperation of the Indiana University Purdue University Indianapolis (IUPUI, USA), the German Federal Environment Agency (UBA, Germany) and the Berlin Centre of Competence for Water (KWB, Germany). The aim of the project is the development of a scheme for natural mitigation zones to protect surface waters from diffuse pollution in rural and semi-rural environments. In particular, key contaminants, applicable management and modelling tools and potential substance removal by constructed wetlands or riparian zones are being studied. Within these frameworks, two case studies are carried out in Brittany, the number one agricultural region in France. A hydrological model is currently being applied on the Ic catchment (92 km2) to test its capability of (i) understanding hydrological, basin-scale regimes, (ii) predicting the effect of mitigation measures and (iii) distinguishing diffusion pathways for different types of contaminants. In the second case study, a constructed wetland in Iffendic on the River Meu is monitored as an example of a natural and inexpensive mitigation option. On the way through the wetland nitrate concentrations from drainage inflows to the river decreased more than tenfold. In the ongoing monitoring, knowledge on hydrological flowpaths is improved to be able to quantify the retention potential of constructed wetlands in Brittany for nitrate and other agriculturally-based pollutants, such as pesticides.