The export of agricultural contaminants from agricultural landscapes of the US Midwest has contributed to the impairment of surface waters throughout the Mississippi River Basin and has been linked to various human health concerns. Natural treatment systems (wetlands, bioswales, bioreactors) can capture agricultural runoff and significantly reduce nutrient loading to downstream waters but there is a paucity of data on the effectiveness of these treatment systems to attenuate the suite of pollutants (nutrients and synthetic organics) typically found in agricultural runoff. This understanding is important given that the degradation of different pollutants involves metabolic pathways that often require different redox environments. As part of the Aquisafe-2 project, a bioretention swale comprising two treatment cells (a subsurface cell in series with a surface cell) was monitored, and its performance evaluated over a three-year period (2011 - 2013). Results showed that the bioswale was moderately efficient with regard to nitrate (NO3-; retention range: 16-58 %). N removal averaging 30 % was measured during a series of wetting events during which the bioswale operated at an estimated average hydraulic retention time (HRT) of 0.97 day. Spatial analysis of the data showed that almost all the NO3- removal occurred in the subsurface cell; however, N removal was also measured in the surface cell under low flow conditions (estimated HRT: 2.5 days). The highest rates of N removal (~ 58 %) were measured when the bioswale stayed wet for several days probably due to the development of a more optimum environment for denitrifying microbes. Nitrate removal capacity was limited by NO3- availability, short retention times during high flows, and the frequent fluctuation between oxic and anoxic conditions, but not by water temperature (8.3-16.6 oC) and dissolved organic carbon (DOC; 1.9 - 29.2 mg C L-1). The bioswale performance with regard to soluble reactive phosphorus (SRP) and atrazine was more variable, with net retention during some periods and net release at other times. The bioswale was a net source of P during most sampling periods with an average SRP release corresponding to 13 % of input, probably due to desorption of water soluble P from the topsoil applied during construction. This interpretation is supported by the progressive decline in P release observed between the first and third year of monitoring. The subsurface and the surface cells contributed almost equally to the fate of P in the bioswale. Likewise, the bioswale was at times a small/moderate sink (13-31 % retention) for atrazine, and a net source (-38 % to -15 %) during periods when the bioswale received overland runoff from the adjacent crop field which bypassed the subsurface cell. Results suggested that competition between atrazine and DOC for sorption sites is a possible mechanism affecting atrazine removal efficiency. Additional work is needed to compare the efficiency of the subsurface and surface cells with regard to atrazine, and elucidate the biogeochemical factors controlling its fate in the bioswale.

The final report of the project COSMA describes the modeling results of four different scenarios regarding the pressure build-up in shallow aquifers due to the injection of CO2 into the sandstone aquifers of the Detfurth Formation. It is based on the “Technical Report on hydrogeological and static structural geological model implementation” (D 2.1) which focuses on the compilation of geological and hydrogeological background data (average values) and the development of a simplified conceptual hydrogeological model for a setting typical for the Northern German Sedimentary Basin as well as the model selection, model parameterization, definition of boundary conditions and implementation in hydrogeological flow model software packages. The hydrogeological model of the Cenozoic includes Quaternary and Tertiary aquifers down to the layer beneath the Rupelian clay. Moreover, a concept for modeling the interaction between deep, consolidated, saline aquifers with unconsolidated freshwater aquifers was developed. This report describes scenario analyses by using the numerical hydraulic model of the Detfurth Formation (Middle Bunter) and the simplified numerical groundwater model of the Cenozoic. The numerical models can be used to assess the key parameters, having an impact on the upconing of deeper saline groundwater beneath the well fields of water works (in shallow aquifer) due to imposed pressure signals.

Emerging subsurface activities (ESA) describe a set of methodologies and technologies using the earths subsurface for energy production or capture and storage of carbon dioxide. The earth’s heat is used as a clean source of energy (deep geothermal systems, DGS), process-related CO2 emissions can be stored in suitable geological formations (geological CO2 storage, GCS) and since the technique of horizontal drilling was developed, the exploitation of unconventional reserves of natural gas via hydraulic fracturing (shale gas extraction, SGE) expanded. At the same time, 97% of global freshwater resources are stored in the earth's subsurface, too, so that exploitation interests may come into conflict with the issue of groundwater and environmental protection. Main objective of deliverable D 3.1 of the COSMA-1 project therefore was to identify best practices of monitoring for geological carbon storage, deep geothermal systems and shale gas extraction projects with special focus on groundwater protection. Chapter 2 summarizes current groundwater monitoring standards, including monitoring network designs for emission-based (operators) and immission-based (water suppliers) monitoring. It further presents an identification of hazards related to ESA and a brief overview about the state of regulation. Finally, knowledge gaps concerning groundwater protection are identified. Chapters 3 to 5 describe for each of the above-named types of ESA the project stages and according monitoring needs and methods. Main target was to identify the key parameters and monitoring network designs ensuring reliable groundwater monitoring. As the most relevant hazards were drilling fluids, fracking fluids and brine migration as well as the mobilisation of methane, and the most likely pathways are leakages due to insufficient well integrity, for all three ESA types, pressure, temperature and TDS were recommended as key monitoring parameters. For shale gas extraction, in addition methane emission should be monitored. Key to any monitoring is i) the baseline sampling prior to the start of subsurface activities and ii) the adequate delineation of the area of review. All further monitoring to be implemented base on site-specific considerations and the authorities’ priorities. In any case, monitoring network should include the up-gradient, down-gradient and depth component. Monitoring wells and equipment should cover the full extension of horizontal bores and additional wells should be placed above potential pathways for fluid (or brine) migration as e.g. fault systems. The use of abandoned wells for monitoring is also recommended. The conception of appropriate monitoring strategies has further to be coordinated with the competent authorities, which have to control the compliance with all requirements. Therefore, site operator and water producer should report their monitoring plans and data at regular intervals to the competent authorities. The findings were summarized by transferring them to a risk management matrix following the Water Safety Plan (WSP) approach (WHO 2009). For shale gas extraction, deliverable D 3.2 will add specific mitigation measures to reduce the previously identified risk of negative impacts on shallow groundwater. Geological carbon storage was further investigated by means of the development of a coupled model for a theoretical case study site in the North-Eastern German Basin in the scope of work package 2 of the COSMA-project (D 2.3).

Different types of managed aquifer recharge (MAR) schemes are widely distributed and applied on various scales in the European countries, but no systematic categorization and compilation existed up to now. The European MAR catalogue presented herein includes a wide range of parameters, e.g. operational information, hydrogeological properties and water quality monitoring for different types of MAR. The database includes currently 270 MAR sites, but is neither a representative nor an exhaustive data compilation. Nevertheless, based on the available data it is shown that MAR plays an important role in the European water supply producing large water quantities for the domestic water supply.

Hydrogeochemical and hydrodynamic surface/groundwater interactions were investigated at the urban floodplain aquifer in Delhi, India. The heavily polluted Yamuna River is in hydraulic contact to the groundwater and river seepage results in a contamination plume. A conceptual redox zonation was developed based on the occurrence or absence of terminal electron acceptors. The redox zonation shows an inverted zonation from sulphate-reducing conditions close to the river over manganese- and iron-reducing conditions to a mixed oxic/suboxic zone. This study shows that the occurrence of problematic substances such as ammonium and arsenic in the groundwater is a consequence of the high load of untreated sewage in the river in combination with losing river conditions. Sequential extraction of aquifer material was performed to obtain information on geochemical availability of arsenic associated with different mineral phases and binding forms. Geogenic and anthropogenic arsenic sources contribute to overall arsenic concentration, and arsenic is found to be attributed mainly to amorphous iron oxide and sulphidic phases in the sediment. The contamination plume at the urban floodplain aquifer makes the groundwater unfit for drinking water purposes.

Emerging countries frequently afflicted by waterborne diseases require safe and cost-efficient production of drinking water, a task that is becoming more challenging as many rivers carry a high degree of pollution. A study was conducted on the banks of the Yamuna River, Delhi, India, to ascertain if riverbank filtration (RBF) can significantly improve the quality of the highly polluted surface water in terms of virus removal (coliphages, enteric viruses). Human adenoviruses and noroviruses, both present in the Yamuna River in the range of 10(5) genomes/100 mL, were undetectable after 50 m infiltration and approximately 119 days of underground passage. Indigenous somatic coliphages, used as surrogates of human pathogenic viruses, underwent approximately 5 log10 removal after only 3.8 m of RBF. The initial removal after 1 m was 3.3 log10, and the removal between 1 and 2.4 m and between 2.4 and 3.8 m was 0.7 log10 each. RBF is therefore an excellent candidate to improve the water situation in emerging countries with respect to virus removal.