Alkaline Sediments Research Articles

Geographic distance and pH drive bacterial distribution in alkaline lake sediments across Tibetan Plateau.

Continent-scale biogeography has been extensively studied in soils and marine systems, but little is known about biogeographical patterns in non-marine sediments. We used barcode pyrosequencing to quantify the effects of local geochemical properties and geographic distance for bacterial community structure and membership, using sediment samples from 15 lakes on the Tibetan Plateau (4–1670 km apart). Bacterial communities were surprisingly diverse, and distinct from soil communities. Four of 26 phyla detected were dominant: Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria, albeit 20.2% of sequences were unclassified at the phylum level. As previously observed in acidic soil, pH was the dominant factor influencing alkaline sediment community structure, phylotype richness and phylogenetic diversity. In contrast, archaeal communities were less affected by pH. More geographically distant sites had more dissimilar communities (r = 0.443, P = 0.030). Variance partitioning analysis showed that geographic distance (historical contingencies) contributed more to bacterial community variation (12.2%) than any other factor, although the environmental factors explained more variance when combined (28.9%). Together, our results show that pH is the best predictor of bacterial community structure in alkaline sediments, and confirm that both geographic distance and chemical factors govern bacterial biogeography in lake sediments.

Microbial lipid records of highly alkaline deposits and enhanced aridity associated with significant uplift of the Tibetan Plateau in the Late Miocene

Saline alkaline sediments and soils are widespread in arid and semiarid regions, but their occurrence in ancient dry periods remains unknown due to the lack of a suitable proxy. On the basis of investigations of modern Chinese soils with a wide pH range of 3.5–9.1, we suggest that the microbial lipid ratio R i/b , i.e., the abundance ratio of archaeal isoprenoid GDGTs (glycerol dialkyl glycerol tetraethers) to bacterial branched GDGTs, indicates the presence of drought-induced alkaline deposits in terrestrial settings. The R i/b is invariant in modern soils with pH 600 mm, but it increases sharply at higher pH values and lower mean annual precipitation ( i/b ratio in a fluviolacustrine section in the Zhada basin of the southwestern Tibetan Plateau, covering the time period 9.2–2.6 m.y. ago. The R i/b ratio remains relatively stable in most intervals but exhibits maxima in some horizons, indicative of the occurrence of severe drought and alkaline deposits in the basin catchment. These occur in fluvial sediments deposited 9 m.y. ago, a critical time with respect to the intensification of the East Asian and Indian monsoons, and the significant uplift of the plateau that has previously been associated with enhanced aridity in Central Asia.

Evaluating Different Wetland Creation Approaches for Irish Cutaway Peatlands Using Water Chemical Analysis

By 2030, 75,000 ha of raised bog owned by Ireland’s largest peat producer, Bord na Mona, are expected to be exhausted. In an effort to rehabilitate Irish cutaway peatlands to maximise their conservation value, large areas have been converted to wetlands using three alternative approaches: total peat removal (TPR), partial peat removal (PPR), and simple rewetting (SR). This paper assesses the success, to date, of the three wetland creation approaches using hydrochemistry as a measure of restoration success and identifies the key variables influencing hydrochemistry in the created wetlands. Chemical analysis suggests major differences between the TPR and SR wetlands while the PPR wetlands exhibited intermediate characteristics. Additionally, principal component analysis highlighted nitrite, conductivity, turbidity, chlorophyll-a, colour, and soluble reactive phosphorus as important hydrochemical factors determining differences among the three wetland creation approaches. This research shows that wetlands underlain by peaty substrates (PPR and SR) may take longer than 10 years to stabilise hydrochemically compared to those wetlands underlain by solely alkaline sediments (TPR) which stabilise quickly. Although wetland ecosystem development may be slower in the PPR and SR wetlands they hold the greatest potential to develop peat forming habitats. Wetland creation represents a viable and valuable post-harvesting land-uses option for cutaway peatlands.

Prokaryotic diversity of an active mud volcano in the Usu City of Xinjiang, China

The Usu mud volcanoes are the largest group of terrestrial mud volcanoes in China. The volcanoes are located in a typical arid and semi-arid region, and the group consists of 36 erupting active mud volcanoes. In this study, the prokaryotic diversity and community structure in the sediment of an active mud volcano were investigated by constructing bacterial and archaeal clone libraries of the 16S rRNA gene. A total of 100 bacterial and 100 archaeal clones were analysed and found to comprise 11 and 7 distinct phylotypes, respectively. The bacterial phylotypes were classified into three phyla (Proteobacteria, Actinobacteria, and Fusobacteria). Of these, Proteobacteria were the most abundant bacterial group, with Deltaproteobacteria dominating the sediment community, and these were affiliated with the order Desulfuromonadales. The archaeal phylotypes were all closely related to uncultivated species, and the majority of the members were related to the orders Methanosarcinales and Halobacteriales of the Euryarchaeota originating from methane hydrate bearing or alkaline sediments. The rest of the archaeal phylotypes belonged to the phylum Crenarchaeota, with representatives from similar habitats. These results suggested that a large number of novel microbial groups and potential methanogenesis may exist in this unique ecosystem.

Veronico beccabungae-Callitrichetum stagnalis (Oberd. 1957) Müller 1962, a plant association new to Poland - quality of habitat

The paper presents a community of water plants that is new to Poland, <em>Veronico beccabungae-Callitrichetum</em> stagnalis (Oberd. 1957) Müller 1962. This community belongs to the class <em>Potametea</em>. It was discovered in the village of Odrowąż near the town of Krapkowice in Silesia (SW Poland). <em>Veronico beccabungae-Callitrichetum stagnalis</em> in Poland occurs within an irregularly shaped shallow underwater spring, located in the distal part of the Oder River’s flood terrace. This plant community covered 0.2 ha in 2008. <em>Callitriche stagnalis</em> predominated in this community. Species such as <em>Callitriche hamulata</em> and <em>Callitriche verna</em> occurred less frequently. An average of five species were counted in a relevé. Alkaline sediments (pH 8.03) occur in the substratum, but sediments with a lower pH value (7.73) occur in the spring’s outflow zone towards the Odra River. Water in the spring, where <em>Veronico beccabungae-Callitrichetum stagnalis</em> occurred, has a medium mineralisation but is rich in dissolved compounds. The condition of this community within the studied habitat could be evidence for highly adaptive abilities and this community's good adjustment to the natural conditions. <em>Veronico beccabungae-Callitrichetum stagnalis</em> is a rare and endangered plant community in Central Europe. The locality of this plant community in Poland should be given species protection.

Biogenic phosphorus in oligotrophic mountain lake sediments: Differences in composition measured with NMR spectroscopy

Phosphorus (P) composition in alkaline sediment extracts from three Swedish oligotrophic mountain lakes was investigated using 31P-NMR spectroscopy. Surface sediments from one natural lake and two mature reservoirs, one of which has received nutrient additions over the last 3 years, were compared with respect to biogenic P composition. The results show significant differences in the occurrence of labile and biogenic P species in the sediments of the different systems. The P compound groups that varied most between these three systems were pyrophosphate and polyphosphates, compound groups known to play an important role in sediment P recycling. The content of these compound groups was lowest in the reservoirs and may indicate a coupling between anthropogenic disturbances (i.e., impoundment) to a water system and the availability of labile P species in the sediment. A statistical study was also conducted to determine the accuracy and reliability of using 31P-NMR spectroscopy for quantification of sediment P forms.

Different native arbuscular mycorrhizal fungi influence the coexistence of two plant species in a highly alkaline anthropogenic sediment

Different species of arbuscular mycorrhizal fungi (AMF) can produce different amounts of extraradical mycelium (ERM) with differing architectures. They also have different efficiencies in gathering phosphate from the soil. These differences in phosphate uptake and ERM length or architecture may contribute to differential growth responses of plants and this may be an important contributor to plant species coexistence. The effects of the development of the ERM of AMF on the coexistence of two co-occurring plant species were investigated in root-free hyphal chambers in a rhizobox experimental unit. The dominant shrub (Salix atrocinerea Brot.) and herbaceous (Conyza bilbaoana J. Remy) plant species found in a highly alkaline anthropogenic sediment were studied in symbiosis with four native AMF species (Glomus intraradices BEG163, Glomus mosseae BEG198, Glomus geosporum BEG199 and Glomus claroideum BEG210) that were the most abundant members of the AMF community found in the sediment. Different AMF species did not influence total plant productivity (sum of the biomass of C. bilbaoana and S. atrocinerea), but had a great impact on the individual biomass of each plant species. The AMF species with greater extracted ERM lengths (G. mosseae BEG198, G. claroideum BEG210 and the four mixed AMF) preferentially benefited the plant species with a high mycorrhizal dependency (C. bilbaoana), while the AMF species with the smallest ERM length (G. geosporum BEG199) benefited the plant species with a low mycorrhizal dependency (S. atrocinerea). Seed production of C. bilbaoana was only observed in plants inoculated with G. mosseae BEG198, G. claroideum BEG210 or the mixture of the four AMF. Our results show that AMF play an important role in the reproduction of C. bilbaoana coexisting with S. atrocinerea in the alkaline sediment and have the potential to stimulate or completely inhibit seed production. The community composition of native AMF and the length of the mycelium they produce spreading from roots into the surrounding soil can be determinant of the coexistence of naturally co-occurring plant species.

Bioleaching of Heavy Metal Polluted Sediment: Influence of Sediment Properties (Part 2)

AbstractA remediation process for heavy metal polluted sediment has previously been developed, in which the heavy metals are removed from the sediment by solid‐bed bioleaching using sulfuric acid as a leaching agent arising from added elemental sulfur (S0). This process has been engineered with Weiße Elster River sediment (dredged near Leipzig, Germany), as an example. Here, six heavy metal polluted sediments originating from various bodies of water in Germany were subjected to bioleaching to evaluate the applicability of the developed process on sediment of different nature: each sediment was mixed with 2 % S0, suspended in water and then leached under identical conditions. The buffer characteristics of each sediment were mainly governed by its carbonate and Ca content, i.e., by its geological background, the redox potential and oxidation state depended on its pre‐treatment (e.g., on land disposal), while the pH value was influenced by both. The added S0 was quickly oxidized by the indigenous microbes even in slightly alkaline sediment. The microbially generated H2SO4 accumulated in the aqueous phase and was in part precipitated as gypsum. Significant acidification and heavy metal solubilization only occurred with sediment poor in buffer substances. With the exception of one sediment, the behavior in bioleaching correlated well with the behavior in titration with H2SO4. Since the content in carbonate seemed to be the most important factor deciding on the leachability of a sediment, oxic Weiße Elster River sediment was mixed with 2 % S0 and 0 to 100 g/kg of ground limestone to simulate various buffer capacities, suspended in water and then leached. The lime did not inhibit microbial S0 oxidation but generated a delay in acidification due to neutralization of formed H2SO4, where the pH only started to decrease when the lime was completely consumed. The more lime the sediment contained, the longer this lag period lasted, and the higher the pH and the lower the fraction of the solubilized heavy metals finally was. Since Cu requires stronger acidic conditions for its solubilization, it responded more sensitively to lime addition than Zn, Ni, and Cd. Heavy metal polluted sediment containing large amounts of carbonate may, in principle, also be remediated by bioleaching, but metal solubilization requires excessive amounts of the leaching agent and is thus uneconomical.

Cloning, expression and characterization of a 46.5-kDa metallopeptidase from Bacillus halodurans H4 sharing properties with the pitrilysin family

A 1242 base pair DNA fragment from Bacillus halodurans H4 isolated from alkaline sediments of Lake Bogoria (Kenya) coding for a potential protease was cloned and sequenced. The hexa-histidine-tagged enzyme was overexpressed in Escherichia coli and was purified in one step by immobilized-metal affinity chromatography (IMAC) on Ni-NTA resin. The protease (ppBH4) presents an inverted zincin motif, HXXEH, which defines the inverzincin family. It shares several biochemical and molecular properties with the clan ME family M16 metallopeptidases (pitrilysins), as well as with database hypothetical proteins that are potential M16 family enzymes. Thus, like insulysin and nardilysin, but contrary to bacterial pitrilysin, ppBH4 is inactivated by sulfhydryl alkylating agents. On the other hand, like bacterial pitrilysin, ppBH4 is sensitive to reducing agents. The enzymatic activity of ppBH4 is limited to substrates smaller than proteins. In contrast to insulin, dynorphin and insulin B-chain are very good substrates for ppBH4 and several cleavage sites are common with those observed with well-characterized pitrilysins. As deduced from amino acid sequence, as well as determined by gel-filtration and SDS-polyacrylamide gel electrophoresis, ppBH4 is an active monomer of 46.5 kDa. This feature distinguishes ppBH4 from all other enzymes of the pitrilysin family so far described whose molecular masses range from 100 to 140 kDa.

Phosphorus fractions and phosphorus sorption characteristics of freshwater sediments and their relationship to sediment composition

Phosphorus was fractionated within a set of sediments operationally divided into acidic, neutral, and alkaline groups. Relationships among fractional distribution of P, concentrations of sediment components important for P-sorption (Fe, Al, organic carbon (OC)), and P-sorption parameters were analyzed using a redundancy analysis method. The NaOH 25 -P fraction prevailed within the group of acidic sediments from forest lakes. NaOH 25 -P followed by BD-P and HCl-P was the largest fraction in the neutral and alkaline sediment groups. Fe and Al were found to be positively correlated with P in the BD and HCl fractions, respectively. A combination of Fe, Al, and OC was positively correlated with P in the NaOH 25 fraction. Maximum sediment P-sorption capacity was the only sorption parameter correlated with P-fractionation; Al and OC in the NaOH 25 fraction were the most significant explanatory constituents. None of the other sorption parameters (initially adsorbed P, adsorption/desorption equilibrium concentration) were correlated with the results of fractionation analysis.

Selenium Immobilization in Evaporation Pond Sediments by in Situ Precipitation of Ferric Oxyhydroxide

Download Hi-Res ImageDownload to MS-PowerPointCite This:Environ. Sci. Technol. 1995, 29, 10, 2639-2646

Xylanolytic anaerobic thermophiles from Icelandic hot-springs

Anaerobic enrichment cultures inoculated with neutral and alkaline (pH 7.0–9.0) sediment and biomat samples from hot-springs in Hverđagerdi and Fluđir, Iceland, were screened for growth on beech xylan from pH 8.0 to 10.0 at 68° C: no growth occured in cultures above pH 8.4. Five anaerobic xylanolytic bacteria were isolated from enrichment cultures at pH 8.4; all five microbes were Gram-positive rods with terminal spores, and produced CO2, H2, acetate, lactate and ethanol from xylan and xylose. One of the isolates, strain A2, grew from 50 to 75° C, with optimum growth near 68° C, and from pH 5.2 to 9.0 with an optimum between 6.8 and 7.4. Taxonomically, strain A2 was most similar to Clostridium thermohydrosulfuricum. At pH 7.0, the supernatant xylanases of strain A2 had a temperature range from 50 to 78° C with an optimum between 68 and 78° C. At 68° C, xylanase activity occurred from pH 4.9 to 9.1, with an optimum from pH 5.0 to 6.6. At pH 7.0 and 68° C, the K m of the supernatant xylanases was 2.75 g xylan/l and the V max was 2.65 × 10−6 kat/l culture supernatant. When grown on xylose, xylanase production was as high as when grown on xylan.

The distribution of nitrogen species and adsorption of ammonium in sediments from the tidal Potomac River and estuary

The distribution of dissolved ammonium, adsorbed ammonium and residual, organic and total nitrogen was measured in Potomac River tidal, transition zone and lower estuary sediments to a depth of 66 cm. For these sediments, exchangeable ammonium, and thereby adsorbed ammonium concentrations, were determined directly using an ammonia electrode in alkaline sediment suspensions. Ammonia electrode data were comparable to data obtained by KCl extraction of fresh sediment. The conventional unitless ammonium adsorption coefficient, calculated as the slope of the regression line drawn when sediment-adsorbed ammonium (μmol g −1 dry wt of sediment) is plotted against interstitial water ammonium (μmol g −1 dry wt sediment), is 1·5 for this system. When a modified ammonium adsorption coefficient is calculated from sediment-adsorbed ammonium concentrations and a ratio of interstitial water ammonium and potassium concentrations, the regression equation through the data has a zero intercept and is more nearly linear than the regression equation of data based on conventional calculations. The use of a ratio including ammonium and potassium concentrations in the interstitial water term takes into account ionic strength variations in the estuary and competition between ammonium and potassium for adsorption sites.

Geochemical and mineralogical indications of pH in lakes and soils in central New Hampshire in the early Holocene1

In central New Hampshire, sediments of some early Holocene lakes were alkaline and contained carbonate minerals despite granitic bedrock and currently acid soils and surface water in their watersheds. Nearby calcareous bedrock contributed to the till of these watersheds while other lakes, more remote from calcareous bedrock, had early Holocene sediments of neutral pH and devoid of carbonate minerals. Calcite rock fragments in alkaline sediments were eroded from alkaline soils in the watershed. Chemical weathering later acidified these soils and surface waters before modem acid precipitation.

Methanosarcina mazei LYC, a New Methanogenic Isolate Which Produces a Disaggregating Enzyme

A methanogenic coccoid organism, Methanosarcina mazei LYC, was isolated from alkaline sediment obtained from an oil exploration drilling site. The isolate resembled M. mazei S-6 by exhibiting different morphophases during its normal growth cycle. It differed from M. mazei S-6 by undergoint a spontaneous shift from large, irregular aggregates of cells to small, individual, irregular, coccoid units. In batch cultures at pH 7.0, M. mazei LYC grew as aggregates during the early growth stage. As the batch culture began exponential growth, the cell aggregates spontaneously dispersed: the culture liquid became turbid, and myriads of tiny (diameter, 1 to 3 mum) coccoid units were observed under phase-contrast microscopy. Disaggregation apparently was accomplished by the production of an enzyme which hydrolyzed the heteropolysaccharide component of the cell wall; the enzyme was active on other Methanosarcina strains as well. Although the enzyme was active when tested at pH 6.0, it apparently was not produced at that pH: when strain LYC was grown at pH 6.0, only cell aggregates were present throughout batch growth. Individual coccoid cells of M. mazei LYC were sensitive to sodium dodecyl sulfate, but the large aggregates of cells were not. Strain LYC rapidly used H(2)-CO(2), in addition to methanol, and mono-, di-, and trimethylamine as methanogenic substrates; acetate was used very slowly. Its optimum growth temperature was 40 degrees C, and its optimum pH was 7.2.

Chemical Availability of Cadmium in Mississippi River Sediment

AbstractThere is concern that changes in the physicochemical conditions occurring during dredging and disposal of polluted sediments may increase chemical mobility and hence bioavailability of sediment‐bound toxicants such as Cd. The objectives of this research were to study the chemical transformations of Cd in freshwater sediment as affected by pH and redox potential under controlled laboratory conditions and predict Cd behavior during dredging and disposal of Cd‐contaminated sediments.Mississippi River sediment suspensions were incubated at four redox potential levels (−150, +50, +250, and +500 mV) at each of three pH levels (5.0, 6.5, and 8.0) and spiked with 0.2 µCi carrier‐free 109Cd/g solids. Sediment suspensions were sequentially extracted for easily mobile and potentially available 109Cd fractions. Essentially all of 109Cd extracted from alkaline sediment suspensions was associated with potentially available chelated, insoluble organic‐bound and reducible fractions and was not affected by changes in oxidation‐reduction conditions. A change from alkaline to acidic pH under moderately oxidized to well‐oxidized conditions resulted in 109Cd transformations from potentially available organic forms to more mobile and readily available dissolved and exchangeable forms. This could create potential hazards of disposal of Cd‐contaminated dredged sediments due to enhanced availability and leaching of Cd as affected by altered physicochemical environments.

The Effect of Flyash Disposal on a Shallow Ground‐Water System

ABSTRACTAt a flyash landfill in southeastern Wisconsin, dry ash has been placed directly in contact with a shallow sand and gravel aquifer. Substantial modification of ground‐water quality has occurred primarily by sulfates, calcium and magnesium. However, after eight years, the contamination has spread less than 200 meters from the site in a permeable aquifer. In addition, toxic metals contained in the ash have proven quite immobile in the ground water. Fortuitous location of the disposal site in alkaline sediment upflow from ground‐water discharge in a marsh appears to have limited the extent of contamination.