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

Methodical problems associated with the assessment of lake eutrophication for designation of zones vulnerable to nitrates Water Framework DirectiveWater Framework Directive

Celem artykułu jest analiza podejścia do oceny eutrofizacji w świetle wymagań dyrektywy azotanowej, Ramowej Dyrektywy Wodnej (RDW) oraz przepisów polskich. W żadnym z tych aktów prawnych nie podaje się metodologii oceny zjawiska. Opracowany w 2005 r., w ramach Wspólnej Strategii Wdrażania RDW, projekt wytycznych do oceny eutrofizacji w kontekście europejskiej polityki wodnej oparty jest na zharmonizowanym podejściu do zagadnienia, uwzględniającym wymagania RDW oraz dyrektywy azotanowej i ściekowej. Oznacza to, że metodologia oceny eutrofizacji przyjęta w RDW powinna być zastosowana również w celu spełnienia wymagań pozostałych dyrektyw i, tym samym, przepisów polskich.An analysis of approaches to the assessment of eutrophication in view of the requirements of nitrate directive, Water Framework Directive and Polish legal acts is presented in this paper. None of the acts gives the methodology of assessing the phenomenon. Draft guidelines for assessing eutrophication in the context of European water policies, prepared in 2005 within the Common Implementation Strategy of the WFD, are based on harmonised approach to the problem with the consideration of the WFD, nitrate directive and urban waste-water treatment directive. It means that the methodology of assessing eutrophication adopted in the WFD should be used in to fulfil the requirements of other directives and Polish regulations

Oxygen Emissions from Single-Crystalline Fe3\text{}_{3}O4\text{}_{4} Surfaces Induced by Low-Energy Ion Bombardments

Negative-charged ion energy spectra of the Fe$\text{}_{3}$O$\text{}_{4}$ (001) and (111) surface revealed large peaks attributed to the O$\text{}^{-}$ recoils from a binary collision. Under Ar$\text{}^{+}$ ion bombardments such an emission was largely affected by the screening effect of the Fe ions. A distinguished peak related to the O$\text{}^{+}$ recoil ions was observed under Ne$\text{}^{+}$ ion bombardments, while such a peak was merged into the high background in the case of Ar$\text{}^{+}$ ion ones. A weak effect from the Verwey transition was found on oxygen emissions. For the (111) surface a small peak characteristic of the O$\text{}^{+}$ recoils from double collisions appeared in the energy spectra around 140-170 K and a minimum was observed in both R$\text{}^{+}$(T) and R$\text{}^{-}$(T) curves under 6 keV Ne$\text{}^{+}$ ion beam

Scanning Tunneling Spectra and Low Energy Ion Scattering Studies of the Verwey Transition in MBE Fe3\text{}_{3}O4\text{}_{4} (100) Thin Film

The (100) surface of magnetite Fe$\text{}_{3}$O$\text{}_{4}$ thin film was studied by a UHV low-temperature scanning tunneling microscope and by an ion scattering spectroscopy. The tunneling spectra revealed a widening of the gap with decreasing temperature, which may be related to the metal-insulator phase transition in this material. A strong effect of this phase transition on ion scattering from such a surface was observed. The temperature dependence of the scattered ion yield, R$\text{}^{+}$(T), revealed two minima at around 100 K and at 125 K under Ne$\text{}^{+}$ bombardment with the primary energy up to 6 keV. The disappearance of the high-temperature minimum at a bombarding energy of 6.5 keV gave a further evidence for the ion velocity dependence of the character of the R$\text{}^{+}$(T) curve, which has been first observed for a MBE Fe$\text{}_{3}$O$\text{}_{4}$ (111) film surface

Scanning Tunneling Spectra and Low Energy Ion Scattering Studies of the Verwey Transition in MBE Fe 3

The (100) surface of magnetite Fe$\text{}_{3}$O$\text{}_{4}$ thin film was studied by a UHV low-temperature scanning tunneling microscope and by an ion scattering spectroscopy. The tunneling spectra revealed a widening of the gap with decreasing temperature, which may be related to the metal-insulator phase transition in this material. A strong effect of this phase transition on ion scattering from such a surface was observed. The temperature dependence of the scattered ion yield, R$\text{}^{+}$(T), revealed two minima at around 100 K and at 125 K under Ne$\text{}^{+}$ bombardment with the primary energy up to 6 keV. The disappearance of the high-temperature minimum at a bombarding energy of 6.5 keV gave a further evidence for the ion velocity dependence of the character of the R$\text{}^{+}$(T) curve, which has been first observed for a MBE Fe$\text{}_{3}$O$\text{}_{4}$ (111) film surface

Surface Investigations of Selected Materials by Low-Energy Ion Scattering Technique

Surfaces of three selected materials were investigated by means of low-energy ion-scattering technique: (1) the magnetite (Fe$\text{}_{3}$O$\text{}_{4}$) exhibiting the so-called Verwey transition (T$\text{}_{V}$(bulk)=125 K) accompanied by a small cubic-monoclinic crystal distortion, (2) the intermetallic compound NdMn$\text{}_{2}$ undergoing an antiferromagnetic-paramagnetic phase transition (T$\text{}_{N}$=104 K) accompanied by a large crystal distortion with a volume change of 1%, and (3) the typical insulator BaTiO$\text{}_{3}$ with two structural transitions below 300 K. The primary energy of the (Ne$\text{}^{+}$, Ar$\text{}^{+}$) ion beam was in the range of 4-8 keV, and the low-energy ion-scattering spectra were collected in the temperature range of 85-300 K. A large influence from the Verwey transition on the neutralization and re-ionization of scattered ions from magnetite surface was observed, while no visible change at the magnetic phase transition in NdMn$\text{}_{2}$ was revealed in the low-energy ion-scattering spectra. A strong dependence of the characteristics of the low-energy ion-scattering spectra on the irradiated time was observed for BaTiO$\text{}_{3}$ indicating that this surface was heavily charged by ion bombardments