WISER deliverable D3.1-4: guidance document on sampling, analysis and counting standards for phytoplankton in lakes

Sampling, analysis and counting of phytoplankton has been undertaken in European lakes for more than 100 years (Apstein 1892, Lauterborn 1896, Lemmermann 1903, Woloszynska 1912, Nygaard 1949). Since this early period of pioneers, there has been progress in the methods used to sample, fix, store and analyse phytoplankton. The aim of the deliverable D3.1-4 is to select, harmonize and recommend the most optimal method as a basis for lake assessment. We do not report and review the huge number of European national methods or other published manuals for phytoplankton sampling and analysis that are available. An agreement on a proper sampling procedure is not trivial for lake phytoplankton. In the early 20th century, sampling was carried out using plankton nets. An unconcentrated sample without any pre-screening is required for quantitative phytoplankton analysis, for which various water samplers were developed. Sampling of distinct water depths or an integral sample of the euphotic zone affects the choice of the sampler and sampling procedure. The widely accepted method to quantify algal numbers together with species determination was developed by Utermöhl (1958), who proposed the counting technique using sediment chambers and inverse microscopy. This is the basis for the recently agreed CEN standard “Water quality - Guidance standard on the enumeration of phytoplankton using inverted microscopy (Utermöhl technique)” (CEN 15204, 2006). This CEN standard does not cover the sampling procedure or the calculation of biovolumes for phytoplankton species, although Rott (1981), Hillebrand et al (1999) and Pohlmann & Friedrich (2001) have contributed advice on how to calculate taxa biovolumes effectively. Willén (1976) suggested a simplified counting method, when counting 60 individuals of each species. For the Scandinavian region an agreed phytoplankton sampling and counting manual was compiled, which has been in use for about 20 years (Olrik et al. 1998, Blomqvist & Herlitz 1998). It is very unfortunate that no European guidance on sampling of phytoplankton in lakes was agreed before the phytoplankton assessment methods for the EU-WFD were developed and intercalibrated by Member States. In 2008 an initiative by the European Commission (Mandate M424) for two draft CEN standards on sampling in freshwaters and on calculation of phytoplankton biovolume was unfortunately delayed by administrative difficulties. Recently a grant agreement was signed between the Commission and DIN (German Institute for Standardization) in January 2012 to develop these standards. We believe this WISER guidance document can usefully contribute to these up-coming standards

Nanoscale textured superconductivity in Ru-substituted BaFe2As2 : a challenge to a universal phase diagram for the pnictides

75As NMR experiments were performed in Ba(Fe1-xRux)2As2 for x=0 to 80%. Magnetic fractions and NMR lineshapes demonstrate that Ru substitution destroys the antiferromagnetic (AF) order inhomogeneously with a magnetic moment distributed from 0.9 to 0 uB. Superconductivity emerges at intermediate Ru doping and coexists with AF order only in the regions where moments are smaller than ~0.3uB, resulting in an original nanoscale texture. This situation contrasts with that of Co substitution, challenging the apparent universality of the phase diagram in Fe-based superconductors

Defining Chlorophyll-a Reference Conditions in European Lakes

The concept of “reference conditions” describes the benchmark against which current conditions are compared when assessing the status of water bodies. In this paper we focus on the establishment of reference conditions for European lakes according to a phytoplankton biomass indicator—the concentration of chlorophyll-a. A mostly spatial approach (selection of existing lakes with no or minor human impact) was used to set the reference conditions for chlorophyll-a values, supplemented by historical data, paleolimnological investigations and modelling. The work resulted in definition of reference conditions and the boundary between “high” and “good” status for 15 main lake types and five ecoregions of Europe: Alpine, Atlantic, Central/Baltic, Mediterranean, and Northern. Additionally, empirical models were developed for estimating site-specific reference chlorophyll-a concentrations from a set of potential predictor variables. The results were recently formulated into the EU legislation, marking the first attempt in international water policy to move from chemical quality standards to ecological quality targets

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements