Bacterial metabolism of algal extracellular carbon

Measurements of microbial utilization of extracellular organic carbon (EOC) released by phytoplankton commonly consider only EOC fractions subject to rapid uptake. Questions remain whether other EOC fractions are metabolized, what portion is labile, and with what assimilation efficiency this carbon substrate is utilized. 14 C-EOC was prepared by incubation of the natural mixed planktonic community from an oligotrophic lake with H 14 CO 3 in the light. 14 C-EOC which was not rapidly removed by heterotrophs remained in solution and was isolated by filtration. This residual EOC was inoculated with lake microheterotrophs in laboratory microcosms, and utilization kinetics were determined through long-term assays of cumulative 14 CO 2 production. Time-courses for 14 CO 2 production were consistent for all assays and were well described by a deterministic mixed-order degradation model. On twelve sampling occasions, from 29% to 76% of residual 14 C-EOC was labile to further metabolism by lake heterotrophs. First-order rate constants for EOC utilization showed a mode of 0.05 to 0.15 per day. From 33% to 78% of gross 14 C-EOC uptake was respired (mean 50%), indicating appreciable return of algal EOC to the pelagic food web as microbial biomass.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42876/1/10750_2004_Article_BF00015524.pd

Stability of west final slope of Bełchatów Mine in light of geological observation and specialized measurements with consideration of salt dome

W artykule przedstawiono sposób monitorowania zachowania się górotworu w stałym zboczu zachodnim wyrobiska górniczego Bełchatów, w rejonie występowania wysadu solnego Dębina. Zaprezentowano wyniki pomiarów prowadzonych w okresie od 2005 roku do grudnia 2009 roku. Są to pomiary reperów powierzchniowej sieci obserwacyjnej rozbudowywanej na stałym zboczu zachodnim, sieci niwelacyjnej założonej na powierzchni terenu nad wysadem solnym, deformacji wgłębnych obserwowanych w inklinometrach oraz zmian ciśnień w wysadzie solnym mierzone sondą Glotzla. Powyższe wyniki przedstawiono w nawiązaniu do postępu robót górniczych. W tym okresie stałe zbocze zachodnie zostało wyprofilowane w zakresie rzędnych +198/+110m n.p.m. co umożliwiło zaprezentowanie również krótkiej charakterystyki budowy geologicznej odsłanianej w rejonie wysadu solnego Dębina. Przedstawiono również wyniki obserwacji makroskopowych prowadzonych na skarpach i półkach stałych zbocza zachodniego. Dotychczasowe wyniki pomiarów pozwoliły na skorelowanie obserwowanych deformacji z postępem robót górniczych oraz wydzielenie dwóch obszarów zagrożeń osuwiskowych na stałym zboczu zachodnim.This article describes the method of monitoring of rock-mass behavior in west final slope of mining pit Bełchatów in area of salt dome Dębina. Presented are the results of measurements conducted during time period 2005 - December 2009. These are the measurements of fixed survey points constituting the terrain surface observation network, that is intensified on west final slope, leveling network of observation points deployed on terrain surface in area of salt dome, deep deformations monitored using inclinometers and measurements of pressure changes in salt dome measured using Glootzl probe device. Results of above listed measurements are presented in accordance with mining works advances. During this period the final west slope of the pit was formed in the scope of elevations +198/+110m a.s.l. which allowed for also presenting the brief description of geological structure revealed in area of Dębina salt dome. Also presented are results of macroscale observations conducted on the final pit benches of west slope. To-date results of the measurements allowed for correlation between the observed deformations and mining works advances and also allowed for designating of two areas of slide hazard on the west final slope of the Bełchatów pit

The use of the innovative measurements technology in slope stability monitoring of the "Żelazny Most" waste plant

W artykule zostały opisane elementy systemu monitoringu geotechnicznego Składowiska "Żelazny Most", zainstalowane w latach 2007-2008. Szczególną uwagę zwrócono na technologie niestosowane dotychczas w Polsce. Opisano instalację głębokich inklinometrów i piezometrów wyposażonych w strunowe czujniki do pomiaru ciśnienia wody porowej, instalowane bezpośrednio w zaczynie cementowo-bentonitowym. Przedstawiono także technologię instalacji zespolonej inklinometru i czujników strunowych w jednym otworze wiertniczym.The paper describes the elements of the geotechnical monitoring system installed at "Żelazny Most" waste plant from 2007 to 2008. Special attention was paid at technologies previously not used in Poland. The authors present installation of deep inclinometers and fully-grouted method installed piezometers containing vibrating wire water pressure sensors. Innovative technology of integrated installation of inclinometer and pressure sensors in single borehole was also presented

Temporal and Stoichiometric Patterns of Algal Stimulation of Litter-Associated Heterotrophic Microbial Activity

Periphyton communities associated with submerged plant detritus contain interacting autotrophic and heterotrophic microbes, and are sites of extracellular enzymatic activity. The strength and nature of these interactions might be expected to change over time as microbial communities develop on plant litter. Microbial interactions and enzymatic activity can be altered by nutrient availability, suggesting that litter stoichiometry could also affect these phenomena.We grew wetland plants under ambient and nutrient‐enriched conditions to generate plant litter of differing nutrient content. In two experiments, we investigated: (1) the influence of algal photosynthesis on fungal and bacterial production and the activities of four extracellular enzymes throughout a 54‐day period of microbial colonisation and growth; and (2) the influence of litter stoichiometry on these relationships.Ambient and nutrient‐enriched standing‐dead plant litter was collected and then submerged in wetland pools to allow for natural microbial colonisation and growth. Litter samples were periodically retrieved and transported to the laboratory for experiments manipulating photosynthesis using the photosystem II inhibitor DCMU (which effectively prevents algal photosynthetic activity). Algal (14C‐bicarbonate), bacterial (3H‐leucine), and fungal (14C‐acetate) production, and β‐glucosidase, β‐xylosidase, leucine aminopeptidase, and phosphatase activities (MUF‐ or AMC‐labelled fluorogenic substrates) were measured under conditions of active and inhibited algal photosynthesis.Photosynthesis stimulated overall fungal and bacterial production in both experiments, although the strength of stimulation varied amongst sampling dates. Phosphatase activity was stimulated by photosynthesis during the first, but not the second, experiment. No other enzymatic responses to short‐term photosynthesis manipulations were observed.Microbial communities on high‐nutrient litter occasionally showed increased extracellular enzyme activity, fungal growth rates, and bacterial production compared to communities on non‐enriched litter, but algal and fungal production were not affected. Litter stoichiometry had no effects on fungal, bacterial, or enzymatic responses to photosynthesis, but the mean enzyme vector analysis angle (a measure of P‐ versus N‐acquiring enzyme activity) was positively correlated to litter N:P, suggesting that elevated litter N:P led to an increase in the relative activity of P‐acquiring enzymes.These results supported the hypothesis that algal photosynthesis strongly influences heterotrophic microbial activity on macrophyte leaf litter, especially that of fungi, throughout microbial community development. However, the strength of this photosynthetic stimulation does not generally depend on small differences in litter nutrient content.Stimulation of microbial heterotrophs by algal photosynthesis could drive diurnal shifts in periphyton community and aquatic ecosystem function, as well as linking green (photoautotroph‐based) and brown (detrital‐based) food webs