[en] Chichoj lagoon has lost 71.6 ha in last 45 years, equivalent to 65% of its area on 1946. At the present, lagoon shows a great invasion of vegetation, with a trend to disappear if this process continues. Physicochemical data evaluation indicated an evident lymnological stress over lagoon due to minimal natural and significant anthropogenic contributions. Temperature was defined by physical factors as sunlight irradiation periods and caloric exchange with wind, promoting the mixing of its water between december and january. Dissolved oxygen concentrations were typical of euthrophic lakes, with over saturation in surface waters an anoxia below few meters depth describing a non-dependent temperature trend. The main affluent river contributions were oxygen-d efficient. pH behavior was related with dissolved oxygen, due to narrow relation between acidity and redox mechanisms in euthrophic waters. Lagoon and affluent river conductivities showed ionic materials contributions from basin (due to its variation with climatic changes), anthropogenic contributions (observed in affluent river) and metabolic activity from sediments speeded up in last portion of lagoon, draining great amounts of ionic substances through effluent river. Redox potentials indicated the trend of reductive process instead of oxidative ones in the affluent river and below 7 m depth in lagoon. Surface and Profile data evaluation suggested the presence of a point-source of contaminants and nutrients, and evidenced the metabolic activity produced over them in lagoon, expressed as a visual euthrophic condition. Next paper will describe nutrients and other water quality parameters behaviors and their interrelation with the physicochemical parameters described in this paper. 1 map, 5 tabs.(Author)

[en] Highlights: • Present day methods deliver new knowledge about socio-ecological past of the lake. • Long term investigation reveals shifting goal setting of restoration over time. • Different, intertwined temporal scales complicate lake restoration endeavors. • Interannual weather variability influences restoration endeavors. • Prevailing understandings influence the anticipated futures of the lake. - Abstract: The history and future of the restoration efforts at the hypereutrophic southern Finnish lake, Tuusulanjärvi, are investigated. The interdisciplinary study is conducted within a modified DPSIR- framework, which allows us to both trace back and envision the future of the dynamics of the complex socio-ecological processes involved in restoration. The study covers the time period from the early 1970s up to 2030. The longitudinal study integrates environmental historical, limnological, and futures studies. The analyses reveal the multiple time scales of social and ecological processes present in long term restoration, the changing perceptions of and emphasis on restoration goals and outcomes over time, and the challenges that incidental and uncertain parameters, such as weather conditions, pose to sustainable and efficient restoration endeavors.

[en] In-situ characterization and assessment of arsenic (As) mobility in sediments was scarce. In this study, the distributions of labile As at a vertical resolution of 2 mm were obtained in the sediments of a large Lake Taihu through in-situ measurements using a Zr-oxide diffusive gradients in thin films (Zr-oxide DGT) technique. The DGT-labile As, interpreted as DGT flux (F_DGT), exhibited three different patterns in the lake, with all the patterns generally showing an increasing mobility followed by a decreasing mobility with sediment depth. The mobility of As could be characterized by the average F_DGT (0.06–1.27 pg cm⁻² s⁻¹) in the top 10 mm surface sediments, the maximal F_DGT (F_DGT-M, 0.14–2.44 pg cm⁻² s⁻¹) in the end of the initial increasing phase of F_DGT, and the diffusion length (ΔL, 28–66 mm) from the depth showing the F_DGT-M to the sediment-water interface. The upward mobilization of labile As from the deep sediments to the surface sediments and overlying water became evident when F_DGT-M > 1.7 pg cm⁻² s⁻¹ or ΔL < 41 mm. The results, for the first time, showed a prospect in in-situ risk assessment of the pollution of sediment As. It was suggested that the increasing mobility of As in the upper sediments was controlled by the reduction of As(V) and the reductive dissolution of Fe(III) (hydr)oxides, while the decreasing mobility in the deep sediments was attributed to immobilization of As(III) by secondary Fe(II)-bearing minerals. - Highlights: • The mobility of As in sediments was characterized in-situ with a high-resolution DGT. • The DGT-labile As in sediments exhibited three basic patterns in vertical distribution. • The mobility of labile As increased in the upper layers and decreased in the deep sediments. • A visible pollution of labile As appeared from the deep sediments when F_DGT-M > 1.7 pg cm⁻² s⁻¹. • The DGT-labile As was a sensitive indicator in reflection of the pollution of sediment As. - In-situ DGT measurements showed a risk of As pollution from sediments when F_DGT-M > 1.7 pg cm⁻² s⁻¹ or ΔL < 41 mm.

[en] The high-mountain lakes of Saliencia (El Valle, La Cueva, Calabazosa and Cerveriz), in the Somiedo Natural ark (Asturias, NW Spain), have been subject to different anthropogenic pressures, including metal mining, cattle grazing, damming activities and water channelling work for hydroelectric exploitation. This paper reports the results of a recent geochemical and limnological study conducted in these lakes, for which no previous study existed in the literature. Based on depth profiles of temperature, conductivity, pH and ORP, as well as dissolved oxygen, chlorophyll-a, organic carbon, nutrient and metal concentration, we discuss the impact of anthropogenic pressure on the lakes. In the sampling period (July to September, 2014-2016), most of the lakes showed a marked stratification with vertical gradients as a result of different physical and (bio)geochemical processes. All the lakes showed a good environmental state with no apparent metal pollution. However, this set of mountain lakes is not homogeneous with regard to nutrient availability, primary productivity, or hypolimnetic oxygen deficit and a range of trophic conditions exist from oligotrophic (El Valle) to eutrophic (Calabazosa). This trend shows a good correlation with total phosphorus concentration (e.g., 10 µg/L P in El Valle vs. 35 µg/L P in Calabazosa), though erosive processes in the catchment may also have contributed to increase the oxygen consumption rate through an import of allochthonous organic matter. Higher nitrate contents seem to characterize the areas with higher grazing pressure (e.g., El Valle), though the obtained data do not allow us to establish any evident relationship between cattle activity and eutrophication.

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[en] During the lecture meeting of the working committee for waste water problems of the German Fishery Association, papers were presented on current problems of waste pollution and on the potential effects of climate changes on the fishing industry. (EF)

[en] We investigated effects of subtle nutrient enrichment and metal pollution on different levels of biological organization (i.e. whole assemblage, population and individual) of species-rich assemblages. We used rockpools as model system, applying a multi-factorial sampling design to test hypotheses on differences between disturbed and reference locations. Results indicated that disturbed and reference locations supported similar assemblages, as well as individual fitness-related life-traits were ineffective to discriminate between the two conditions. In contrast, assemblages responded to pollution through a reduction of the abundance of sensitive species and a proliferation of tolerant species, although these alterations were detectable only once the influence of dominant taxa was down-weighed by data transformation. Present findings suggest that, contrarily to individual level variables, assemblage structure after data transformation and patterns of distribution and abundance of differently sensitive taxa would be a powerful tool to detect effects of subtle pollution on species-rich assemblages. - Highlights: • Disturbed and reference localities supported similar assemblages. • Data transformation was necessary to detect pollution effects on assemblages. • Sensitive canopy species were substituted by turf and mussels. • Fitness-related life-traits were ineffective to discriminate pollution effects. - Assemblage structure after data transformation and abundance of canopy species were the best tools to detect effects of subtle pollution

[en] The combined use of methods of passive dosimetry of the status of atmospheric air, phytoindication, and cartographic visualization of data made it possible to elaborate and substantiate approaches to evaluation of the effect of atmospheric air contamination on the eutrophication of forest ecosystems under urban conditions.

[en] Effluents containing phosphorous as phosphate ions are frequently discharged in freshwater resources contributing to the eutrophication and directly interfering in the biological equilibrium. Clam shell residues and sewage sludge were combined for preparing efficient adsorbents for phosphate removal from aqueous medium. The adsorbents were characterized before and after adsorption testing, and the adsorption equilibrium and kinetics were investigated. Phosphate removal of 89 ± 1% was attained for samples prepared with 0.1 < X < 1.0, where X corresponds to sewage sludge/clam shell mass ratio. The analyses of the experimental errors indicated that the phosphorous removal followed the Elovich kinetic model, which describes adsorption in very heterogeneous surfaces. On the other hand, the best modelling was achieved using the Koble–Corrigan isotherm model, which incorporate different aspects of both Langmuir and Freundlich isotherms to represent the equilibrium data. The observed adsorption capacity (21.4 mgP g⁻¹) are comparable or greater to that observed for other adsorbents described in the literature.