Verträge zur Rehabilitation von Wasserkraftwerken

Aufsatz veröffentlicht in: "Wasserbau-Symposium 2021: Wasserbau in Zeiten von Energiewende, Gewässerschutz und Klimawandel, Zurich, Switzerland, September 15-17, 2021, Band 1" veröffentlicht unter: https://doi.org/10.3929/ethz-b-00049975

Einfluss von Temperatur und Düngezeitpunkt bei unterschiedlichen Beregnungsmustern in mit Biogasgülle gedüngten Böden

Ziel der Arbeit war die Untersuchung des Einflusses von Temperatur, Beregnungs-muster und Bodenfeuchte zum Zeitpunkt der Düngung auf die Kohlenstoff (C)- und Stickstoff (N)-Austräge in Böden, die mit 33 kg N ha-1 Biogasgülle gedüngt wurden. Das Inkubationsexperiment wurde bei 13,5°C und 23,5°C durchgeführt und zeigte, dass die C- und N-Dynamik stark von der Düngung sowie von der Temperatur abhängig war. Die CO2-Emissionen stiegen bei einer Temperaturerhöhung um 10°C um das 1,7-fache, die N2O-Emissionen um das 3,7-fache an. Stickstoff wurde überwiegend als NO3- (16% des Biogasgülle-N) mit dem Sickerwasser ausgetragen. Die Beregnungsmuster und die Bodenfeuchte zum Düngezeitpunkt hatten hingegen nur geringe Auswirkungen

Einfluss unterschiedlicher Beregnungsmuster auf die Dynamik von C und N aus Biogasgülle und Rottemist im Boden

Die Bodenfeuchte übt einen erheblichen Einfluss auf den Abbau von organischen Düngern aus. Wenig bekannt ist jedoch die Bedeutung verschiedener Beregnungsmuster auf den Kohlenstoff (C)- und Stickstoff (N)-umsatz. Ziel dieser Arbeit war die Untersuchung des Einflusses unterschiedlicher Beregnungsmuster auf die C- und N-Dynamik in mit Biogasgülle (BG) oder Rottemist (RM) gedüngtem Boden. Ungestörte Bodensäulen wurden mit BG oder RM gedüngt (100 kg N ha-1) bzw. blieben ungedüngt (Kontrolle) und wurden 140 Tage bei 13,5 °C inkubiert. Die Beregnungsvarianten umfassten kontinuierliche Beregnung (3 mm Tag-1), Austrocknungs-und Wiederbefeuchtungs-Zyklen (alle vier Wochen für eine Woche 13,5 mm Tag-1) und Starkniederschläge (alle drei Wochen für 1 Tag 24 mm Tag-1, sonst 2 mm Tag-1). Jede Beregnungsvariante wies eine durchschnittliche Regenintensität von 3 mm Tag-1 auf. Kumulative CO2- und N2O-emissionen der BG-gedüngten Böden lagen bei 92,8 g CO2-C m-2 und 162,4 mg N2O-N m-2, während die Emissionen der RM-gedüngten Böden Werte von 87,8 g CO2-C m-2 und 38,9 mg N2O-N m-2 erreichten. Beide organischen Dünger riefen eine signifikant höhere CO2-Produktion im Vergleich zu den Kontrollen hervor. Eine signifikante Steigerung der N2O-Produktion konnte ausschließlich in BG-gedüngten Böden beobachtet werden. Der Einfluss der Beregnungsvarianten auf die kumulativen C- und N-Austräge war nicht signifikant. Kumulative NO3--Auswaschungen lagen in BG-gedüngten bei 9,2 g NO3--N m-2, in RM-gedüngten Böden bei 6,1 g NO3--N m-2 und in den Kontrollen bei 4,7 g NO3--N m-2. Die Höhe der NO3--N -auswaschungen war unabhängig von den Beregnungsvarianten. Die Studie zeigte, dass Beregnungsmuster keinen signifikanten Einfluss die CO2- und N2O-emissionen sowie auf die NO3--Auswaschungen haben, insofern der Boden nicht vollständig ausgetrocknet ist

Auswirkungen eines Pflugereignisses auf die Verteilung von Aggregaten und organischem Material in Grünlandböden.

Die Auswirkungen sporadischen Pflügens sind noch nicht vollständig verstanden. Ziel dieser Arbeit war die Effekte sporadischen Pflügens (mit Ackerzwischennutzung) auf Kohlenstoff- Vorräte sowie die Erträge und Verteilung der Aggregate und leichten Fraktionen zu untersuchen. Zwei Jahre nach einem Pflugereignis sind noch deutliche Unterschiede, vor allem in der obersten Bodenschicht, vorhanden. So wurde in dieser Bodenschicht eine signifikante (p<0,05) Abnahme der Vorräte an organischem Kohlenstoff, großer Makroaggregate und der freien leichten Fraktion festgestellt. Fünf Jahre nach dem Pflugereignis sind diese Effekte zwar noch sichtbar, jedoch wesentlich schwächer ausgeprägt und nicht mehr signifikant

Screening tools for early neuropsychological impairment after aneurysmal subarachnoid hemorrhage

Background Although most aneurysmal subarachnoid hemorrhage (aSAH) patients suffer from neuropsychological disabilities, outcome estimation is commonly based only on functional disability scales such as the modified Rankin Scale (mRS). Moreover, early neuropsychological screening tools are not used routinely. Objective To study whether two simple neuropsychological screening tools identify neuropsychological deficits (NPDs), among aSAH patients categorized with favorable outcome (mRS 0-2) at discharge. Methods We reviewed 170 consecutive aSAH patients that were registered in a prospective institutional database. We included all patients graded by the mRS at discharge, and who had additionally been evaluated by a neuropsychologist and/or occupational therapist using the Montreal Cognitive Assessment (MoCA) and/or Rapid Evaluation of Cognitive Function (ERFC). The proportion of patients with scores indicative of NPDs in each test were reported, and spearman correlation tests calculated the coefficients between the both neuropsychological test results and the mRS. Results Of the 42 patients (24.7%) that were evaluated by at least one neuropsychological test, 34 (81.0%) were rated mRS 0-2 at discharge. Among these 34 patients, NPDs were identified in 14 (53.9%) according to the MoCA and 8 (66.7%) according to the ERFC. The mRS score was not correlated with the performance in the MoCA or ERFC. Conclusion The two screening tools implemented here frequently identified NPDs among aSAH patients that were categorized with favorable outcome according to the mRS. Our results suggest that MoCA or ERFC could be used to screen early NPDs in favorable outcome patients, who in turn might benefit from early neuropsychological rehabilitation.Peer reviewe

The role of macro-aggregation in regulating enzymatic depolymerization of soil organic nitrogen

Extracellular enzymatic depolymerization of polymeric organic nitrogen (PON) is a rate-limiting step in N mineralization. However, enzymatic accessibility to PON might be regulated by physical occlusion of the PON resulting from the architectural packing of soil minerals during aggregate formation. To examine the extent to which enzymatic accessibility to PON is regulated by soil aggregation, we put forward a new approach involving the comparison of relationships between potential N depolymerase activity (protease and β-glucosaminidase; as an estimate of the potential to produce depolymerized products) and net N mineralization (as a bioassay for actual low molecular weight dissolved ON production) in aggregated and corresponding disaggregated soil. Soils were sampled from grassland (GL) and arable land (AL), separated by dry sieving into fractions (4.75-2, 2-0.25 and 0.25-0.063 mm) and fractions mixed (4:4:1 by mass, respectively) to obtain constructed aggregated soils. Corresponding disaggregated soils were prepared using a mortar and pestle. This procedure mainly disrupted the 4.75-2 mm (large macro-aggregate) fraction. Disaggregation significantly promoted (p<0.05) net N mineralization rates by 1.3 times and 1.5 times in GL and AL soil, respectively. When net N mineralization - potential N depolymerase relationships for GL were examined, a greater slope parameter for disaggregated compared to aggregated soil (p=0.001; ANCOVA) quantified the extent to which this promoted N mineralization could be attributed to disruption of macroaggregate-increased enzymatic accessibility to PON. For AL, which had low protease and β-glucosaminidase activity, promoted N mineralization rate could not be attributed to increased protease + β-glucosaminidase accessibility to PON reflecting a possible role for other N depolymerases and/or osmolyte/lysate effects. By proposing how differences between mineralization-depolymerase relationships for soils differing in aggregation status might, with assumptions, be interpreted to identify the role of physical occlusion in protection of PON, we give new insight on the regulation of enzymatic depolymerization by physical protection through macro-aggregation for soils from contrasting land use

Comparative Assessment of the Effect of Synthetic and Natural Fungicides on Soil Respiration

As toxic pesticide residues may persist in agricultural soils and cause environmental pollution, research on natural fungicides to replace the synthetic compounds is currently increasing. The effect of the synthetic fungicide chlorothalonil and a natural potential fungicide on the soil microbial activity was evaluated here by the substrate-induced respiration by addition of glucose (SIR), as bioindicator in two soils (Eutrophic Humic Gley—GHE and Typic Eutroferric Chernosol—AVEC). The induced soil respiration parameter was followed during 28 days after soil treatment either with chlorathalonil (11 μg·g−1), or the methanolic fraction from Polymnia sonchifolia extraction (300 μg·g−1), and 14C-glucose (4.0 mg and 5.18 Bq of 14C-glucose g−1). The 14C-CO2 produced by the microbial respiration was trapped in NaOH (0.1 M) which was changed each two hours during the first 10 h, and 1, 3, 5, 7, 14 and 28 days after the treatments. The methanolic fraction of the plant extract inhibited (2.2%) and stimulated (1.8%) the respiration of GHE and AVEC, respectively, but the synthetic chlorothalonil caused 16.4% and 2.6% inhibition of the respiration, respectively of the GHE and AVEC soils. As the effects of the natural product were statistically small, this bioindicator indicates that the methanolic fraction of the Polymnia sonchifolia extract, which has fungicide properties, has no environmental effects

Compared to conventional, ecological intensive management promotes beneficial proteolytic soil microbial communities for agro-ecosystem functioning under climate change-induced rain regimes

Projected climate change and rainfall variability will affect soil microbial communities, biogeochemical cycling and agriculture. Nitrogen (N) is the most limiting nutrient in agroecosystems and its cycling and availability is highly dependent on microbial driven processes. In agroecosystems, hydrolysis of organic nitrogen (N) is an important step in controlling soil N availability. We analyzed the effect of management (ecological intensive vs. conventional intensive) on N-cycling processes and involved microbial communities under climate change-induced rain regimes. Terrestrial model ecosystems originating from agroecosystems across Europe were subjected to four different rain regimes for 263 days. Using structural equation modelling we identified direct impacts of rain regimes on N-cycling processes, whereas N-related microbial communities were more resistant. In addition to rain regimes, management indirectly affected N-cycling processes via modifications of N-related microbial community composition. Ecological intensive management promoted a beneficial N-related microbial community composition involved in N-cycling processes under climate change-induced rain regimes. Exploratory analyses identified phosphorus-associated litter properties as possible drivers for the observed management effects on N-related microbial community composition. This work provides novel insights into mechanisms controlling agro-ecosystem functioning under climate change

Is soluble protein mineralisation and protease activity in soil regulated by supply or demand?

Protein represents a major input of organic matter to soil and is an important source of carbon (C) and nitrogen (N) for microorganisms. Therefore, determining which soil properties influence protein mineralisation in soil is key to understanding and modelling soil C and N cycling. However, the effect of different soil properties on protein mineralisation, and especially the interactions between soil properties, are poorly understood. We investigated how topsoil and subsoil properties affect protein mineralisation along a grassland altitudinal (catena) sequence that contained a gradient in soil type and primary productivity. We devised a schematic diagram to test the key edaphic factors that may influence protein mineralisation in soil (e.g. pH, microbial biomass, inorganic and organic N availability, enzyme activity and sorption). We then measured the mineralisation rate of 14C-labelled soluble plant-derived protein and amino acids in soil over a two-month period. Correlation analysis was used to determine the associations between rates of protein mineralisation and soil properties. Contrary to expectation, we found that protein mineralisation rate was nearly as fast as for amino acid turnover. We ascribe this rapid protein turnover to the low levels of protein used here, its soluble nature, a high degree of functional redundancy in the microbial community and microbial enzyme adaptation to their ecological niche. Unlike other key soil N processes (e.g. nitrification, denitrification), protease activity was not regulated by a small range of factors, but rather appeared to be affected by a wide range of interacting factors whose importance was dependent on altitude and soil depth [e.g. above-ground net primary productivity (NPP), soil pH, nitrate, cation exchange capacity (CEC), C:N ratio]. Based on our results, we hypothesise that differences in soil N cycling and the generation of ammonium are more related to the rate of protein supply rather than limitations in protease activity and protein turnover per se