Morphology,distribution, and preservation potential of microbial mats in the hydromagnesite-magnesite playas of the Cariboo Plateau,British Columbia,Canada

Benthic microbial mats are common in the alkaline hydromagnesite-magnesite playa lakes of Interior British Columbia. Four main zones are recognized based on mat morphology that can be related to the type and duration of wetting. From the basin margin toward the playa centre they are: (i) vegetated hummocky ground; (ii) polygonal hummocky ground; (iii) low-domal and stratiform mats, and (iv) laterally continuous and pustular mats. Mats in peripheral mudflats are commonly mineralized by hydromagnesite, mostly precipitated by capillary evaporation of shallow groundwaters. Mats forming in the ephemeral lake tend to have lower carbonate content.Although widespread, the mats are poorly preserved in the Holocene sedimentary record. Underlying sediments are commonly weakly bedded, disturbed or massive. Desiccation, dehydration, wetting-drying cycles, and grazing by invertebrates cause fragmentation of mats at the surface, facilitating erosion. Cryogranulation, interstitial mineral precipitation, vesiculation, bioturbation, compaction, and volume changes associated with diagenesis, disrupt and destroy lamination in the upper few centimetres. Most surviving organic matter is lost by early microbial degradation.     

Isolation and Molecular Identification of Fungi with Magnesite Enrichment Potential from KÜMAŞ Quarries in Turkey

Abstract

Magnesite is an important raw material used in various industrial applications, especially the production of high-temperature resistant materials. Due to its high reactant nature, magnesite ore is not found in pure form and it contains a great variety of pollutants such as calcium compounds, which restrict its use when exceeding 1% of the ore. Thus, the development of efficient strategies for the removal of pollutants remains a crucial step for magnesite utilization. In this regard, our present work was conducted to isolate and identify active fungal strains that remove calcium pollutants without changing the main magnesium content of the ore. For this aim, magnesite ore samples were collected from two quarries (Turanoca?? and Ortaocak) of KÜMA? Magnesite Inc. and fungal isolation studies were done by using the ore’s flora. Active isolates were chosen according to their CaCO₃ and MgCO₃ dissolving capabilities and identified by using conventional light microscopy and molecular characterization techniques. 71 fungal isolates were obtained from the isolation step and 14 of them were chosen as active isolates that solve calcium compounds while not affecting the magnesium component. The data of the microscopic examination and 18S rDNA gene sequence analysis showed that 14 active strains with magnesite enrichment potential grouped in Aspergillus alliaceus (3), Aspergillus flavus (2), Aspergillus leporis (1), Aspergillus nomius (1), Fusarium tricinctum (2), Penicillium chrysogenum (1) and Penicillium sp. (4).     

Isolation and Molecular Identification of Bacteria with Magnesite Enrichment Potential from Turanocak and Ortaocak Quarries in Kütahya-Turkey

Abstract

In this study, bacteria were isolated from two different magnesite quarries in Turanocak and Ortaocak mine in Kütahya-Eski?ehir region, one of the largest processed magnesite reserves in Turkey. The obtained isolates have a potential to solve important magnesite pollutant CaCO₃ but incapable to solve magnesium that has the most crucial role in the industry. Thus, potential bacteria were identified to be used for magnesite enrichment studies. The obtained isolates were identified and characterized according to the morphological, physiological, biochemical, and molecular techniques (16S rDNA PCR). According to the gene sequencing analysis Bacillus genus bacteria have the ability to solve CaCO₃. The data of the 16S rDNA gene sequence showed that there were 13 active strains grouped in Bacillus. These active strains; Bacillus sp (3), Bacillus atrophaeus (2), Bacillus thuringiensis (1), Bacillus circulans (1), Bacillus simplex (3), Bacillus endophyticus (1) Bacillus drentensis (1) and Bacillus idriensis (1).     

Conventional and Molecular Identification of Bacteria with Magnesite Enrichment Potential from Local Quarries in Erzurum

In this study, the bacteria having ore enrichment potential were isolated from three different magnesite quarries located in Erzurum-Askale borderlines. The obtained isolates were identified and characterized according to the conventional (morphological, physiological and biochemical tests) and molecular techniques (fatty acid methyl ester profiles (FAME), BOX PCR and 16S rDNA). According to sequence analysis, they were determined as Exiguobacterium aurantiacum (4), Exiguobacterium sibiricum (2), Bacillus sp. (2), Staphylococcus epidermidis (2), Staphylococcus haemolyticus (1), Shewanella baltica (1) and Klebsiella oxytoca (1), respectively.     

Accumulative Characteristics of Some Plant Species to Magnesium around a Magnesite Mine Area in Northeast China

The deposition of Mg-rich dust from magnesite calcination can lead to serious soil contamination. As an efficient remediation method, phytoremediation is often used to remove contaminants from the environment. However, no information is available on phytoremediation of Mg-contaminated soils. In this study, we determined the Mg concentrations in above- and belowground parts of six dominant plant species and soils (0–20 cm layer) beneath these plants in a magnesite mining region in Northeast China. Mg was enriched in leaves of all six species. Translocation factors (TF) of all six species were far greater than 1. Enrichment factors (EF) of Kochia scoparia, Cassia nomame, and Hordeum jubatum were 1.1, 1.1, and 1.0, respectively, while those of the other three species were not greater than 0.5. The results suggest that Kochia scoparia, Cassia nomame, and Hordeum jubatum are the potential Mg-accumulators, and could be used for remediation of Mg-contaminated soils.     

不同硅吸收效率水稻品种根系对硅素水平的响应

为明确硅对水稻根系生长发育的影响,以4个硅吸收效率不同的水稻品种（高效吸收品种TN1、白香粳和低效吸收品种卷叶粳、一目惚）为材料,采用国际水稻研究所的营养液配方水培试验,设置0(T₁)、1.25 (T₂)和2 (T₃) mmol·L^-1 3个硅素水平,研究了不同硅素水平对不同基因型水稻根系和地上部干物质量、根条数、侧根数、根总长和根直径等的影响.结果表明：随硅素水平的提高,水稻各品种均表现为根系干物质量、根冠比、侧根数和根总长逐渐减少,地上部干物质量、根条数和根直径逐渐增大.较高的硅素水平有利于水稻不定根的分化发育,而不利于侧根的分化发育.在较低的硅素水平下,硅吸收效率高的基因型水稻TN1和白香粳的根干物质量和根冠比显著高于硅吸收效率低的品种卷叶粳和一目惚,其中白香粳的侧根数和根总长均显著高于卷叶粳和一目惚.可见,根总长和侧根数是引起水稻硅素吸收差异的主要原因.     

Carbonate Mineralogy Along a Biogeochemical Gradient in Recent Lacustrine Sediments of Gallocanta Lake (Spain)

Three sedimentary subenvironments, palustrine (GP), marginal lacustrine (GML) and central lacustrine (GCL), were compared regarding water chemistry and microbial activity in order to explain the differences in the carbonate mineralogical composition of the upper sediment layer in Gallocanta Lake, a shallow hypersaline environment in Northeastern Spain. Horizontal heterogeneity was considerable, salinity ranged from 5 to 116 (‰) for the GP and GCL subenvironments respectively. Sulfate, Mg ^{2 +} , and Ca ^{2 +} concentrations covaried among them and with salinity. The relative abundance of Mg-bearing carbonates, including high-Mg calcite, dolomite and hydrated Ca-magnesite, increased with the salinity. They were absent from the GP subenvironment, where only calcite precipitates, and maximum abundances were found in the GCL subenvironment (61%), where salinity, sulfate, and Mg ²⁺ concentrations were highest. Every subenvironment presented specific microecological characteristics. The microbial community of the GCL subenvironment lacked of oxygenic photosynthesis, while the microbial communities of GML and GP subenvironments were photosynthetically active. Vertical profiles of sulfide and pH at the water-sediment interface revealed clear differences between the GCL and GML subenvironments as well. Sulfide was detected below the oxic layer in the GCL subenvironment and increased with depth, but it was undetected in the GML subenvironment. The precipitation of Mg-bearing carbonates with different Mg:Ca proportions occurs at different stage along a biogeochemical gradient, where increasing salinity and sulfate content favour the anaerobic oxidation of organic carbon by dissimilatory sulfate reduction.     

投加石灰石和菱镁矿对酸化土壤上马尾松(Pinus massoniana)林的影响

为了确定酸化森林生态系统的修复效果,在重庆铁山坪的马尾松林内设立了6个10m×10m的样地,其中2个作为对照样地,另外4个分别在土壤表面施撒石灰石和菱镁矿粉末,各有2个重复。在处理前和处理1a后的生长季末各进行了一次植被观测,协方差分析和多重比较的结果显示投加修复剂对马尾松生长的影响已经初步显现,马尾松的胸径增量和针叶平均长度都有显著的增加,而针叶中Ca、Mg元素含量也表现出显著的差别。另外,立木更新的变化、细根生物量的增加和物种多度的变化也较明显,总体来说生态系统有恢复的趋势。土壤上层细根的增加较快,这与在土壤表面施撒修复剂,上层土壤的化学变化较显著是一致的。而两种修复剂对生态系统的影响也表现出明显的差异,相对而言,施撒菱镁矿的效果可能会更好。由于土壤修复的效果是长期的,其影响观测还将继续下去。     

Magnesite Enrichment with Pseudomonas oryzihabitans Isolated from Magnesite Ore

Magnesite is a primary source of magnesium and its compounds. The major problem in its practical use are the impurities such as silicon, iron and calcium carbonate. Some magnesite ores in Turkey cannot be used due to a high amount of CaCO₃ (≥3%). In this study, bacterial isolates from magnesite quarries in Mersin were tested by plate assay for their ability to decalcify magnesite. A bacterial strain producing the largest clear zones in the plate assay was identified as Pseudomonas oryzihabitans by 16S rDNA-PCR and applied to magnesite ore. It was found to be effective in decalcifying magnesite ore without significant concurrent dissolution of the magnesium carbonate.