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Detection of enzymatic activities has been proposed as a rapid surrogate for the culture-based microbiological pollution monitoring of water resources. This paper presents the results of tests on four fully automated prototype instruments for the on-site monitoring of beta-d-glucuronidase (GLUC) activity. The tests were performed on sediment-laden stream water in the Hydrological Open Air Laboratory (HOAL) during the period of March 2014 to March 2015. The dominant source of faecal pollution in the stream was swine manure applied to the fields within the catchment. The experiments indicated that instrument pairs with the same construction design yielded highly consistent results (R2 = 0.96 and R2 = 0.94), whereas the results between different designs were less consistent (R2 = 0.71). Correlations between the GLUC activity measured on-site and culture-based Escherichia coli analyses over the entire study period yielded R2 = 0.52 and R2 = 0.47 for the two designs, respectively. The correlations tended to be higher at the event scale. The GLUC activity was less correlated with suspended sediment concentrations than with E. coli, which is interpreted in terms of indicator applicability and the time since manure application. The study shows that this rapid assay can yield consistent results over a long period of on-site operation in technically challenging habitats. Although the use of GLUC activity as a proxy for culture-based assays could not be proven for the observed habitat, the study results suggest that this biochemical indicator has high potential for implementation in early warning systems.

An important issue in construction of organic photovoltaic cells concerns the selective contacts. Here, especially the modification of the hole-extraction is challenging, as energy levels have to match the polymer's highest occupied molecular orbital (HOMO). We took the view to the mutual anode interface and we sought for a solution-based alternative for commonly used PEDOT:PSS – with an eye on improving the hole-extraction with an inorganic interlayer. We present copper iodide (CuI) as a versatile inorganic p-type semiconductor that meets the requirements for enhanced charge extraction in donor polymers. We applied two types of anthracene-containing PPE–PPV block–copolymers that recently gained attention as efficient active absorbers in bulk heterojunction photovoltaic cells. We report on the advantages using CuI as hole-selective contact and show an improvement of the power conversion efficiency in polymer-based solar cells.

Understanding the fate of fecal pollution in the landscape is required for microbial risk analysis. The aim of this study was to assess the patterns and dynamics of beta-D-glucuronidase (GLUC), which has been suggested as a surrogate for fecal pollution monitoring, in a stream draining an agricultural headwater catchment. Automated enzymatic on-site measurements of stream water and sediments were made over two years (2014-2016) to quantify the sources and pathways of GLUC in a stream. The event water fraction of streamflow was estimated by stable isotopes. Samples from field sediments on a hillslope, streambed sediment and stream water were analyzed for GLUC and with a standard E. coli assay. The results showed ten times higher GLUC and E. coli concentrations during the summer than during the winter for all compartments (field and streambed sediments and stream water). The E. coli concentrations in the streambed sediment were approximately 100 times those of the field sediments. Of the total GLUC load in the study period, 39% were transported during hydrological events (increased streamflow due to rainfall or snowmelt); of these, 44% were transported when the stream contained no recent rainwater. The results suggested that a large proportion of the GLUC and E. coli in the stream water stemmed from resuspended streambed sediments. Moreover, the results strongly indicated the existence of remnant populations of GLUC-active organisms in the catchment. usc Refereed/Peer-reviewed