In situ enzyme activities of filamentous scum bacteria in municipal activated sludge wastewater treatment plants

In situ phosphatase, esterase, lipase, and β‐glucuronidase activities were investigated in filamentous scum bacteria by ELF (enzyme labeled fluorescence)‐technology. Microthrix parvicella exhibited significant activities for all four enzymes with lipase activity being the highest. In situ activities were considerably higher in activated sludge as compared to scum indicating M. parvicella growth to occur mainly in the sludge fraction. “Nocardioform actinomycetes” showed significant activities for phosphatase, esterase, and β‐glucuronidase, lipase activity was only moderate. Activities revealed to be similar for activated sludge and scum. As population densities of enzyme‐active actinomycetes were noticeably higher in scum they presumably find good growth conditions in the scum layer. Enzyme activities in Nostocoida limicola morphotypes were only low with no lipase activity being detected. Due to their phylogenetic diversity activity assignment should be combined with fluorescence in situ hybridization (FISH). Numerous type 0041/0675 and type 1851 filaments showed all but lipase activity. However, some of their attached bacteria revealed to be lipase‐active. Only a few morphotype 0092 filaments revealed phosphatase, esterase, and β‐glucuronidase activity. ELF investigations proved suitable for monitoring in situ filamentous activity. Present imponderabilities of Eikelboom morphotype phylogenetic affiliation are discussed.     

An ancient linked fluid migration system: cold-seep deposits and sandstone intrusions in the Panoche Hills, California, USA

In central California, Maastrichtian–Danian shales of the Moreno Formation preserve a fluid migration system that developed along the western margin of the former Great Valley forearc basin. The system consists of a network of interconnected sandstone intrusions linked to overlying fossiliferous carbonates whose geochemistry, fauna, and petrology are characteristic of active cold seeps. The system is approximately 800 m thick and represents episodic migration and seafloor expulsion of fluids over at least 0.5×10⁶ years. This locality has the most extensive exposure yet discovered of a complete seep system, from underlying fluid pathways to seep deposits and associated communities.     

Sieve mesh size and quantitative chironomid paleoclimatology

The minimum sieve mesh size for fossil chironomid analysis is usually set at 100 μm, to ensure adequate recovery of small species. Yet taking into account the labor intensity of sorting and identifying fossil chironomid remains, the large numbers of samples requiring processing in paleoclimate studies with high temporal resolution, and the increasing need to engage non-specialist analysts in this work, it seems appealing to sieve samples through a larger mesh size that would mainly retain easier-to-see, easier-to-extract and easier-to-identify fossil specimens. In this study we evaluated the influence of sieve mesh size on chironomid-based quantitative paleoenvironmental reconstructions in African lakes. We developed two chironomid-salinity calibration data sets based on either the >100 μm or >150 μm size fractions of surface-sediment fossil assemblages, and compared the performance of salinity-inference models derived from them. We find that, despite ∼35% additional fossil loss, restriction to >150 μm data did not appreciably affect individual taxon optima or tolerances, and resulted in only a modest reduction of mean taxon richness per lake. Parameters of statistical model performance were as good, or better than those of models based on the >100 μm data, albeit only after excluding two atypically dilute (<100 μS/cm) lakes from the calibration. Application of inference models based on >150 μm or >100 μm data to a 200-year fossil record from Lake Abiyata, Ethiopia, produced very similar trends, amplitudes and uncertainty ranges of inferred past salinity change. Restriction to >150 μm data reduced the mean fossil yield of core samples by ∼20% on average, i.e. fossil loss was markedly lower than in surface-sediment samples. Using the larger mesh size reduced sample processing time by up to 50%, partly by removing a significant proportion of visually obstructive organic debris, and partly by allowing a greater fraction of chironomid fossils to be identified directly in the sorting tray. The fraction of 1st instar group taxa in surface-sediment samples was reduced from 13% to 3%, increasing the mean taxonomic resolution of fossil assemblages, and thus their ecological specificity.     

Sulphur Enrichment in Organic Matter of Eastern Mediterranean Sapropels: A Study of Sulphur Isotope Partitioning

Sulphur isotope compositions and S/C ratios of organic matter were analysed in detail by combustion-isotope ratio monitoring mass spectrometry (C-irmMS) in eastern Mediterranean sediments containing three sapropels of different ages and with different organic carbon contents (sapropel S1 in core UM26, formed from 5–9 ka ago with a maximum organic carbon content of 2.3 wt%; sapropel 967 from ODP Site 160-967C, with an age of 1.8 Ma and a maximum organic carbon content of 7.4 wt%; and sapropel 969 from ODP Site 160-969E, with an age of 2.9 Ma and a maximum organic carbon content of 23.5 wt%). Sulphur isotopic compositions (34S) of the organic matter ranged from -29.5 to +15.8 and the atomic S/C ratio was 0.005 to 0.038. The organic sulphur in the sediments is a mixture of sulphur derived from (1) incorporation of 34S-depleted inorganic reduced sulphur produced by dissimilatory microbial sulphate reduction; and (2) biosynthetic sulphur with an isotopic signature close to seawater sulphate. The calculated biosynthetic fraction of organic sulphur in non-sapropelic sediments ranges from 68–87%. The biosynthetic fraction of the organic sulphur of the sapropels (60–22%) decreases with increasing organic carbon content of the sapropels. We propose that uptake of reduced sulphur into organic matter predominantly took place within sapropels where pyrite formation was iron-limited and thus an excess of dissolved sulphide was present for certain periods of time. Simultaneously, sulphide escaped into the bottom water and into sediments below the sapropels where pyrite formation occurred.     

UV-B susceptibility and photoprotection of Arctic Daphnia morphotypes

UV-B tolerance and susceptibility of high Arctic morphotypes of the Daphnia pulexl D. tenebrosa complex were assessed by in situ experiments at Ny-Ålesund, Svalbard (79°N). Animals from local ponds were exposed to ambient light plus additional UV-B from lamps in a greenhouse facility. Taxonomic affinities did not appear as major determinants of UV susceptibility, but a major difference in UV-B tolerance was seen between morphotypes with pigmented carapaces and those without, the latter being far more susceptible. Assays on levels of carotene and the anti-oxidant enzymes catalase and superoxide dismutase did not reveal clear-cut differences between populations, and could not account for the higher tolerance in pigmented populations. Levels of glutathione transferase were higher in the transparent population, however. In the absence of blue light and UV, laboratory reared animals did not reconstitute their carapace melanization after moulting, indicating that short-wave light is the cue for melanin synthesis. Tests on melanized individuals and individuals of the same population reared indoors through 1-2 moults supported the major role of melanin for UV protection. Periods with high UV exposure during hatching of ephippia could induce shifts in morphotype or clonal dominance.     

Eutrophication assessment of the Baltic Sea Protected Areas by available data and GIS technologies

Concerning increased degradation of marine ecosystems, there is a great political and institutional demand for an array of different tools to restore a good environmental status. Thereby, eutrophication is acknowledged as one of the major human induced stressors which has to be monitored and reduced. The present study concentrates on an assessment of the eutrophication status of the Baltic Sea Protected Areas by use of available data and GIS technologies. Two geodata layers were used for analysis: (1) a map on the eutrophication status of the Baltic Sea generated by the Helsinki Commission applying the HELCOM Eutrophication Assessment Tool (HEAT), and (2) modelled data on atmospheric nitrogen deposition made available by the European Monitoring and Evaluation Programme (EMEP). The results yielded comprehensive and conclusive data indicating that most of the BSPAs may be classified as being 'affected by eutrophication' and underlining the need to decrease the overall emissions of nutrients.     

Performance of limestones laden with mixed salt solutions of Na2SO4–NaNO3 and Na2SO4–K2SO4

The behaviour of two types of limestones having a different porosity, Maastricht and Euville limestone, laden with aqueous solutions of equimolar mixtures of sodium sulphate/sodium nitrate or sodium sulphate/potassium sulphate was investigated. At 50 % RH, the efflorescences on Maastricht samples during the first 30 h of drying consisted of similar amounts of thenardite and darapskite in case of an equimolar mixture of sodium sulphate/sodium nitrate while those on Euville samples under the same conditions contained mainly darapskite. After drying at 20 °C and 85 % RH, thenardite, formed through the precipitation and dehydration of mirabilite, was mostly detected in the efflorescences on both Maastricht and Euville samples. Re-wetting by increasing the RH from 50 to 85 % resulted in substantial damage on Maastricht stone laden with an equimolar mixture of sodium sulphate/sodium nitrate as a consequence of high supersaturation of mirabilite. In case of a contamination with equimolar amounts of sodium sulphate and potassium sulphate, the efflorescence on both limestones during drying at 50 % RH contained predominantly aphthitalite. The observed crystallisation behaviour is compared to the theoretical behaviour. The results indicate a strong influence of stone properties on the crystallisation behaviour of salt mixtures.     

Spatial variability of chironomid death assemblages in the surface sediments of a fluctuating tropical lake (Lake Naivasha,Kenya)

Studies addressing within-lake variability of fossil chironomid assemblages are very few, and all deal with hydrologically stable temperate lakes where the question of spatial integration mostly relates to the mixing of faunal assemblages associated with shallow, warm-water habitat and those associated with deeper, cold-water habitat. Here we study within-lake variability of surface-sediment chironomid assemblages in the fairly large (∼100–170 km² since 1983) and shallow (Z _max = 5–8 m) fluctuating tropical lake basin of Lake Naivasha, Kenya, and compare the patterns observed with those in two smaller adjacent basins, one similarly shallow (Lake Oloidien, 5.1–5.7 km2, 5–8 m), the other deep and stratified (Crescent Island Crater, 1.9 km², 14–17 m). Chironomid assemblages were analysed in core-top samples and surface sediments along inshore to offshore transects, and how well individual samples represented the total (basin-wide mean) subfossil assemblage was considered both in terms of taxon richness and taxon percent composition. Within-lake variability of subfossil chironomid concentrations (with generally higher absolute values in nearshore samples) could be explained by effects of sediment winnowing and focusing, whereas between-lake variability reflected their relative susceptibility to wind-driven sediment disturbance or bottom anoxia. In all study lakes, but most significantly in lakes Naivasha and Oloidien, species distribution in the subfossil chironomid assemblages showed a strong nearshore to offshore gradient, which in these shallow lakes, reflects the dominant control of substrate and food quality on species distribution in the living community. Particularly in the larger basins, nearshore samples better represented the total lake assemblage than offshore samples, because the former always contained a component of mud-dwelling species whereas the latter often lacked a component of macrophyte-dwelling species. Our results show that although sedimentation dynamics in the shallow, wind-stressed Lake Naivasha is dominated by frequent resuspension and random sediment redistribution, the near- to offshore gradient in chironomid habitat remains imprinted on subfossil assemblages. We conclude that also in shallow fluctuating lakes, given sufficient size, incomplete pre-burial spatial integration of habitat-specific chironomid assemblages can be exploited for within-lake calibration of environmental gradients.     

Subfossil Chironomidae from Lake Tanganyika, East Africa 1. Tanypodinae and Orthocladiinae

Analysis of subfossil remains of larval Chironomidae in 38 surface-sediment samples from between 53 and 189 m depth in Lake Tanganyika (East Africa) yielded 77 different morphotypes, including 7 Tanypodinae, 19 Orthocladiinae, and 51 Chironominae. Character-state differences between these morphotypes resemble differences at the species level in the better-known Holarctic fauna, hence we consider most of our Lake Tanganyika morphotypes equivalent to morphological species. Individual morphotypes were identified to species, genus, or tribe level depending on current alpha-taxonomic knowledge on the larvae of the group concerned, and the taxonomic resolution of preserved diagnostic features. This paper presents taxon diagnoses and an illustrated key to the Tanypodinae and Orthocladiinae in this Lake Tanganyika collection, with the aim to promote consistency of identification in studies using African Chironomidae as biological indicators of natural and anthropogenic environmental change in lacustrine ecosystems.     

Scum in Nutrient Removal Plants: The Role of Carbon Sources in “Microthrix parvicella” Growth

Scum formation is a widespread problem in activated sludge nutrient removal plants. It often comes along with an excessive development of the filamentous bacterium “Microthrix parvicella” stabilizing the flotation process. As “M. parvicella” was found to depend on long‐chain fatty acids (LCFA) as sole carbon source not only in vitro but also in situ, some options of in‐situ substrate supply are discussed. Wastewater concentrations of fatty acids in the range of 2 to 15 mg L^‐1 and homologue concentrations from synthetic surfactant degradation below 10 mg L^‐1 rule out these substrates as source for excessive biomass production. They might, however, well be suitable for start‐up of a “M. parvicella” population. Build‐up of excessive biomass might rely on fatty acid supply originating in cell walls of lysed stationary phase bacteria of long residence time sludge fractions such as scum layers. Moreover, biogenic surfactants such as rhamnolipids have been proved to be an excellent carbon source for excessive biomass production in vitro.