Future ocean acidification will be amplified by hypoxia in coastal habitats

Ocean acidification is elicited by anthropogenic carbon dioxide emissions and resulting oceanic uptake of excess CO₂ and might constitute an abiotic stressor powerful enough to alter marine ecosystem structures. For surface waters in gas-exchange equilibrium with the atmosphere, models suggest increases in CO₂ partial pressure (pCO₂) from current values of ca. 390 μatm to ca. 700–1,000 μatm by the end of the century. However, in typically unequilibrated coastal hypoxic regions, much higher pCO₂ values can be expected, as heterotrophic degradation of organic material is necessarily related to the production of CO₂ (i.e., dissolved inorganic carbon). Here, we provide data and estimates that, even under current conditions, maximum pCO₂ values of 1,700–3,200 μatm can easily be reached when all oxygen is consumed at salinities between 35 and 20, respectively. Due to the nonlinear nature of the carbonate system, the approximate doubling of seawater pCO₂ in surface waters due to ocean acidification will most strongly affect coastal hypoxic zones as pCO₂ during hypoxia will increase proportionally: we calculate maximum pCO₂ values of ca. 4,500 μatm at a salinity of 20 (T = 10 °C) and ca. 3,400 μatm at a salinity of 35 (T = 10 °C) when all oxygen is consumed. Upwelling processes can bring these CO₂-enriched waters in contact with shallow water ecosystems and may then affect species performance there as well. We conclude that (1) combined stressor experiments (pCO₂ and pO₂) are largely missing at the moment and that (2) coastal ocean acidification experimental designs need to be closely adjusted to carbonate system variability within the specific habitat. In general, the worldwide spread of coastal hypoxic zones also simultaneously is a spread of CO₂-enriched zones. The magnitude of expected changes in pCO₂ in these regions indicates that coastal systems may be more endangered by future global climate change than previously thought.     

Intergenerational aspects of ecotax reforms – An application to Germany

In a model of overlapping generations and majority voting, we analyze an ecotax reform consisting of the tax rate and the budgetary rule. Revenue can be recycled through a lump-sum transfer or a reduction in pension contributions. Our theoretical results as well as the calibration of our model to the German economy show that the median voter's preferred tax rate may exceed the efficient rate. This holds whenever income of the decisive voter is sufficiently high compared to the average income, as rich individuals benefit more from a reduction in pension contributions than they are harmed by an increase in ecotaxes. The calibration confirms that the median voter prefers the earmarking of tax revenue for reductions in pension contributions to the alternative lump-sum transfer. This is quite an accurate prediction of the situation in Germany. Aging of society as expected for Germany lowers the ecotax in the political equilibrium below its optimal level.     

Singing activity stimulates partner reproductive investment rather than increasing paternity success in zebra finches

Song is used as a signal in sexual selection in a wide range of taxa. In birds, males of many species continue to sing after pair formation. It has been suggested that a high song output after pair formation might serve to attract extra-pair females and to minimise their own partner’s interest in extra-pair copulations. A non-exclusive alternative function that has received only scant attention is that the amount of song might stimulate the own female’s investment into eggs in a quantitative way. We address these hypotheses in a captive population of zebra finches, Taeniopygia guttata, by relating male undirected song output (i.e. non-courtship song) to male egg siring success and female reproductive investment in two different set-ups. When allowed to breed in aviaries, males with the highest song output were no more attractive than others to females in an analysis of 4,294 extra-pair courtships involving 164 different males, and they also did not sire more offspring (both trends were against the expectation). When breeding in cages with two different partners subsequently, females produced larger eggs with more orange yolks when paired to a male with a high song output. These findings suggest that singing activity in paired zebra finch males might primarily function to stimulate the partner and not to attract extra-pair females.     

Assessment of regional climate change impacts on Hungarian landscapes

The assessment of regional climate change impacts combined with the sensitivity of landscape functions by predictive modelling of hazardous landscape processes is a new fundamental field of research. In particular, this study investigates the effects of changing weather extremes on meso-regional-scale landscape vulnerability. Climatic-exposure parameter analysis was performed on a predicted climate change scenario. The exposure to climate change was analysed on the basis of the original data of the meso-scale IPCC A1B climate scenario from the REMO and ALADIN regional models for the periods of 2021–2050 and 2071–2100, and the regional types of climate change impacts were calculated by using cluster analysis. Selected climate exposure parameters of the REMO and ALADIN models were analysed, in particular, for extreme events (days with precipitation greater than 30 mm, heat waves, dry periods, wet periods) and for daily temperature and precipitation. The landscape functions impacted by climate change are proxies for the main recent and future problematic processes in Hungary. Soil erosion caused by water, drought, soil erosion caused by wind, mass movement and flash floods were analysed for the time periods of 1961–1990, 2021–2050 and 2071–2100. Based on the sensitivity thresholds for the impact assessments, the landscape functional sensitivity indicators were interpreted, and an integrative summary of the five indicators was made, differentiating the regions facing only a few or multiple sensitivities. In Central Hungary, the increasing exposure and sensitivity to droughts will be a serious problem when following the REMO scenario. In several regions, most indicators will change the sensitivity threshold from a tolerable risk to an increased or very high risk.     

Characterization of MSWI fly ash through mineralogy and water extraction

This paper investigates the mineralogical characteristics of fresh, aged and hot water extracted MSWI fly ash for providing the baseline information of minerals stability which controls the released heavy metals into the environment. Quantitative determination of bulk phase abundance in the fresh fly ash by the XRD Rietveld refinement method provided composition levels for amorphous and crystalline phases such as potassium tetrachlorozincate (K₂ZnCl₄), gehlenite, halite, quartz, anhydrite, and feldspar. The minerals association in the fly ash is clearly unstable and subject to mineralogical reactions. The phases of K₂ZnCl₄, halite and anhydrite in the fresh fly ash were involved in hydration and dissolution/precipitation processes to form new minerals such as the Zn-bearing mineral gordaite, syngenite, gypsum and hydrocalumite. The solubility-controlling phases and extractability of heavy metals were examined in a Soxhlet hot water-extractor. Here the soluble salts were simply removed from fly ash while Ca-, Al-, Si- and SO₄²⁻-bearing hydrate minerals were precipitated from the extraction solution. Furthermore, a low release of heavy metals Zn, Pb and Cd in hot water was noticed, indicating a strong retention of the trace metals in the mineral phases remaining in the insoluble fly ash residues.     

Correlation of six anthropogenic markers in wastewater, surface water, bank filtrate, and soil aquifer treatment

Six trace contaminants (acesulfame (ACE), sucralose (SUC), carbamazepine (CBZ), diatrizoic acid (DTA), 1H-benzotriazole (BTZ) and its 4-methyl analogue (4-TTri)) were traced from wastewater treatment plants (WWTPs) to receiving waters and further to riverbank filtration (RBF) wells to evaluate their prediction power as potential wastewater markers. Furthermore, the persistence of some compounds was investigated in advanced wastewater treatment by soil aquifer treatment (SAT). During wastewater treatment in four conventional activated sludge WWTPs ACE, SUC, and CBZ showed a pronounced stability expressed by stable concentration ratios in influent (in) and effluent (out) (ACE/CBZ: in45, out40; SUC/CBZ: in1.8, out1.7; and ACE/SUC: in24, out24). In a fifth WWTP, additional treatment with powdered activated carbon led to a strong elimination of CBZ, BTZ, and 4-TTri of about 80% and consequently to a distinctive shift of their ratios with unaffected compounds. Data from a seven month monitoring program at seven sampling locations at the rivers Rhine and Main in Germany revealed the best concentration correlation for ACE and CBZ (r(2) = 0.94) and also a good correlation of ACE and CBZ concentrations to BTZ and 4-TTri levels (r(2) = 0.66 to 0.82). The comparison of ratios at different sampling sites allowed for the identification of a CBZ point source. Furthermore, in Switzerland a higher consumption of SUC compared to Germany can be assumed, as a steadily increasing ACE/SUC ratio along the river Rhine was observed. In RBF wells a good correlation (r(2) = 0.85) was again observed for ACE and CBZ. Both also showed the highest stability at a prolonged residence time in the subsurface of a SAT field. In the most peripheral wells ACE and CBZ were still detected with mean values higher than 36 μg L(-1) and 1.3 μg L(-1), respectively. Although SUC concentrations in wastewater used for SAT decreased by more than 80% from about 18 μg L(-1) to 2.1 μg L(-1) and 3.5 μg L(-1) in these outlying wells, the compound was still adequate to indicate a wastewater impact in a qualitative way.     

Sink–float density separation of post-consumer plastics for feedstock recycling

The paper focuses on current mechanical waste processing technologies and out-of-the-box processes linked to the processing of coal and mineral resources, to ensure high-quality feedstock recycling of polyolefin-rich post-consumer plastic fractions. Moreover, the study aims to provide the basis for the technical and economic feasibility of the chemical recycling route of this plastic fraction. When evaluating common mechanical processes, either dry or wet ones, sink–float separation in a cylindrical centrifugal force separator achieves the best results. It combines the advantages of a simple, robust apparatus of low complexity and high capacity with selective separation through the accelerated settling of particles in the centrifugal field. Furthermore, the disconnection of the separation medium feed from the solid input increases residence times. Based on the above findings, a pilot-scale plant was constructed which consists of a centrifugal force separator and a hydro jig for the pre-separation of heavy waste components. Several test campaigns were conducted to separate polyolefins from various waste fractions. Two-stage processing in the centrifugal force separator rendered almost 90 wt% of polyolefin content in the produced lightweight fraction and of polyolefin recovery. One-stage processing, on the other hand, resulted in reduced polyolefin content in the lightweight fraction.

     

Adsorption von Phenolderivaten an Substrate unterschiedlich anthropogen überprägter Böden

The organic ground substance (OGS) is an adsorbent of many of the harmful substances found in productive soil. Using the example of adsorption enthalpy of Phenol derivatives, it can be shown that the organic connection on the OGS in sewage farm land and nonsewage farm land is comparable. Based on the OGS content, the sewage farm land showed itself to be the worse adsorbent. The reasons lie in blockage at the adsorption points caused by other molecules, but also because not all of the OGS on the sewage farm land functions as an adsorbent.