Anaerobic Degradation of Phenolic Compounds

Mononuclear aromatic compounds are degraded anaerobically through three main pathways, the benzoyl-CoA pathway, the resorcinol pathway, and the phloroglucinol pathway. Various modification reactions channel a broad variety of mononuclear aromatics including aromatic hydrocarbons into either one of these three pathways. Recently, a further pathway was discovered with hydroxyhydroquinone as central intermediate through which especially nitrate-reducing bacteria degrade phenolic compounds and some hydroxylated benzoates. Comparison of the various strategies taken for the degradation of aromatics in the absence of oxygen demonstrates that the biochemistry of breakdown of these compounds is determined largely by the overall reaction energetics and, more precisely, by the redox potentials of the electron acceptor systems used. Nitrate reducers differ in their strategies significantly from those used by sulfate-reducing or fermenting bacteria.     

Aufnahmepfade von POPs in Biota

Zusammenfassung  POPs (persistente organische Schadstoffe), die an aquatischen Sedimenten binden, k?nnen zurück in Nahrungsnetze gelangen und so zu einem Risiko für aquatische Organismen werden. Dabei kann die Bioakkumulation solcher Substanzen in endobenthischen, sedimentfressenden Invertebraten (z.B. aquatische Oligochaeten) eine gro?e Rolle spielen. Diese Würmer dienen vielen benthivoren Fischen als Nahrung. Letztere nehmen über diesen Weg sedimentgebundene Chemikalien auf und k?nnen hierbei deutlich h?here K?rperkonzentrationen (body residues) erreichen als durch die Anreicherung aus der Wasserphase. Die angereicherten Rückst?nde k?nnen im weiteren Verlauf der Nahrungskette an Glieder h?herer trophischer Ebenen weitergegeben werden. Zur standardisierten Bestimmung der Bioakkumulation und — magnifikation wurde eine einfache, zwei trophische Stufen umfassende Labornahrungskette etabliert. Diese bestand aus dem endobenthischen Oligochaeten Tubifex tubifex und dem Dreistachligen Stichling (Gasterosteus aculeatus) als Pr?dator. Die Experimente wurden mit ¹⁴C-markiertem Hexachlorbenzol in dotiertem künstlichem Sediment und rekonstituiertem Wasser durchgeführt. Um den Einfluss benthischer Beuteorganismen zu quantifizieren, wurden die Fische gegenüber dotiertem Wasser bzw. Sediment (Biokonzentration), vorexponierten Würmern (Biomagnifikation) und Kombinationen dieser Aufnahmepfade exponiert. HCB wurde entlang der Labornahrungskette deutlich angereichert. Es konnte gezeigt werden, dass die Exposition gegenüber der Kombination s?mtlicher Aufnahmepfade zu deutlich h?herer Anreicherung in den Fischen führte als im Falle einzelner Expositionspfade. Der Vergleich der Einzelergebnisse lie? den Schluss zu, dass neben dem freien Wasserk?rper die kontaminierte Nahrung der Hauptaufnahmeweg für den Fisch war. Bei der Bewertung von POPs wie HCB hinsichtlich Biomagnifikation und ‘secondary poisoning’ sollten daher Nahrung und Sediment als Expositionspfade unter Verwendung von Nahrungsketten-modellen und/oder Labortests st?rker berücksichtigt werden. Reter Spr?rlein war bis Januar 2000 als Ingenieur für Umweltverfahrenstechnik bei der ECT Oekotoxikologie GmbH besch?ftigt und für die HPLC-analytische Aufarbeitung der experimentellen Proben verantwortlich.     

Current EU-27 technical potential of organic waste streams for biogas and energy production

Anaerobic digestion of organic waste generated by households, businesses, agriculture, and industry is an important approach as method of waste treatment – especially with regard to its potential as an alternative energy source and its cost-effectiveness. Separate collection of biowaste from households or vegetal waste from public green spaces is already established in some EU-27 countries. The material recovery in composting plants is common for biowaste and vegetal waste. Brewery waste fractions generated by beer production are often used for animal feeding after a suitable preparation. Waste streams from paper industry generated by pulp and paper production such as black liquor or paper sludge are often highly contaminated with toxic substances. Recovery of chemicals and the use in thermal processes like incineration, pyrolysis, and gasification are typical utilization paths. The current utilization of organic waste from households and institutions (without agricultural waste) was investigated for EU-27 countries with Germany as an in-depth example. Besides of biowaste little is known about the suitability of waste streams from brewery and paper industry for anaerobic digestion. Therefore, an evaluation of the most important biogas process parameters for different substrates was carried out, in order to calculate the biogas utilization potential of these waste quantities. Furthermore, a calculation of biogas energy potentials was carried out for defined waste fractions which are most suitable for anaerobic digestion. Up to 1% of the primary energy demand can be covered by the calculated total biogas energy potential. By using a “best-practice-scenario” for separately collected biowaste, the coverage of primary energy demand may be increased above 2% for several countries. By using sector-specific waste streams, for example the German paper industry could cover up to 4.7% and the German brewery industry up to 71.2% of its total energy demand.     

Post-frontier governance up in smoke? Free-for-all frontier imaginations encourage illegal deforestation and appropriation of public lands in the Brazilian Amazon

ABSTRACT

Post-frontier governance in the Brazilian Amazon highlights the interaction of regulatory technologies, institutions and practices to combat illegal deforestation and appropriation of public lands. While the Amazon fires received tremendous media coverage in 2019, the dismantlement of environmental laws and regulatory agencies has supported the rise in deforestation as early as 2012. We discuss the impact of post-frontier governance in Southwest-Pará by analyzing the spatial distribution of deforestation, territorial management, law enforcement, and environmental regularization from 2000 to 2018. The integration of spatial analysis with qualitative field surveys in the blacklisted municipality Novo Progresso shows that deforestation control largely fails, specifically in undesignated public lands. While land tenure security remains the biggest challenge in the region, the persistent imagination of free-for-all frontier spaces encourages the uncontrolled appropriation of and speculation with public lands. Here, the Rural Environmental Registry (CAR) has been identified as a key instrument to secure land claims.     

Effects of various fatty acid amendments on a microbial digester community in batch culture

Since biogas production is becoming increasingly important the understanding of anaerobic digestion processes is fundamental. However, large-scale digesters often lack online sensor equipment to monitor key parameters. Furthermore the possibility to selectively change fermenting parameter settings in order to investigate methane output or microbial changes is limited. In the present study we examined the possibility to investigate the microbial community of a large scale (750,000 L) digester within a laboratory small-scale approach. We studied the short-term response of the downscaled communities on various fatty acids and its effects on gas production and compared it with data from the original digester sludge. Even high loads of formic acid led to distinct methane formation, whereas high concentrations of other acids (acetic, butyric, propionic acid) caused a marked inhibition of methanogenesis coupled with an increase in hydrogen concentration. Molecular microbial techniques (DGGE/quantitative real-time-PCR) were used to monitor the microbial community changes which were related to data from GC and HPLC analysis. DGGE band patterns showed that the same microorganisms which were already dominant in the original digester re-established again in the lab-scale experiment. Very few microorganisms dominated the whole fermenting process and species diversity was not easily influenced by moderate varying fatty acid amendments - Methanoculleus thermophilus being the most abundant species throughout the variants. MCR-copy number determined via quantitative real-time-PCR - turned out to be a reliable parameter for quantification of methanogens, even in a very complex matrix like fermenter sludge. Generally the downscaled batch approach was shown to be appropriate to investigate microbial communities from large-scale digesters.     

Estimation of efficiency of processing soil samples for pesticide residues analysis

The efficiency of four sample processing methods was tested with eight different types of soils representing the major proportion of cultivated soils. The principle of sampling constant was applied for characterizing the efficiency of the procedures and testing the well-mixed status of the prepared soil. The test material was 14C-labeled atrazine that enabled keeping the random error of analyses 相似文献   

Critical loads and their exceedances at intensive forest monitoring sites in Europe

Intensive forest monitoring by means of harmonised methods has been conducted in Europe for more than a decade. Risks of atmospheric nitrogen and sulphur deposition are assessed by means of calculations of critical loads and their exceedances. In the present study throughfall and bulk deposition of nitrate (N-NO(3)), ammonium (N-NH(4)) and sulphate (S-SO(4)) show marked spatial patterns and temporal trends. In the period of observation (1999-2004), sulphate deposition on intensive monitoring plots decreased by about one quarter. This is in line with the reduction of S deposition by 70% since 1981 in Europe as a result of successful air pollution control politics under the Convention on Long-range Transboundary Air Pollution (CLRTAP). However, sulphate and especially nitrate and ammonium deposition were found to still exceed critical loads at many forest sites, indicating a continued need for further implementation of air pollution abatement strategies.     

Modeling eelgrass spatial response to nutrient abatement measures in a changing climate

For many coastal areas including the Baltic Sea, ambitious nutrient abatement goals have been set to curb eutrophication, but benefits of such measures were normally not studied in light of anticipated climate change. To project the likely responses of nutrient abatement on eelgrass (Zostera marina), we coupled a species distribution model with a biogeochemical model, obtaining future water turbidity, and a wave model for predicting the future hydrodynamics in the coastal area. Using this, eelgrass distribution was modeled for different combinations of nutrient scenarios and future wind fields. We are the first to demonstrate that while under a business as usual scenario overall eelgrass area will not recover, nutrient reductions that fulfill the Helsinki Commission’s Baltic Sea Action Plan (BSAP) are likely to lead to a substantial areal expansion of eelgrass coverage, primarily at the current distribution’s lower depth limits, thereby overcompensating losses in shallow areas caused by a stormier climate.