Pulsed Terahertz Radiation for Sensitive Quantification of Carbonate Minerals.

Quantification of natural carbonate minerals, namely, aragonite, high- and low-Mg calcite, and dolomite provides essential information about biomineralization, carbon cycling on Earth, and the evolution of ocean chemistry, and is also useful in many other scientific, pharmaceutical, and industrial fields. However, X-ray diffractometer has previously been the only practical tool to identify and quantify carbonate minerals, including calcium carbonate (CaCO) polymorphs. We propose new fingerprint terahertz (THz) absorption and reflective index spectra in the 1-6 THz range that probe the lattice phonon modes and can be used for sensitive quantification of these four carbonate minerals, including polymorphs.

Significant contribution of subseafloor microparticles to the global manganese budget.

Ferromanganese minerals are widely distributed in subseafloor sediments and on the seafloor in oceanic abyssal plains. Assessing their input, formation and preservation is important for understanding the global marine manganese cycle and associated trace elements. However, the extent of ferromanganese minerals buried in subseafloor sediments remains unclear.

Cyanobacterial exopolymer properties differentiate microbial carbonate fabrics.

Although environmental changes and evolution of life are potentially recorded via microbial carbonates, including laminated stromatolites and clotted thrombolites, factors controlling their fabric are still a matter of controversy. Herein, we report that the exopolymer properties of different cyanobacterial taxa primarily control the microbial carbonates fabrics in modern examples. This study shows that the calcite encrustation of filamentous Phormidium sp.

Bacteriogenic Fe(III) (oxyhydr)oxides characterized by synchrotron microprobe coupled with spatially resolved phylogenetic analysis.

Ubiquitous presence of microbes in aquatic systems and their inherent ability of biomineralization make them extremely important agents in the geochemical cycling of inorganic elements. However, the detailed mechanisms of environmental biomineralization (e.g.

Metabolic microenvironmental control by photosynthetic biofilms under changing macroenvironmental temperature and pH conditions.

Ex situ microelectrode experiments, using cyanobacterial biofilms from karst water creeks, were conducted under various pH, temperature, and constant-alkalinity conditions to investigate the effects of changing environmental parameters on cyanobacterial photosynthesis-induced calcification. Microenvironmental chemical conditions around calcifying sites were controlled by metabolic activity over a wide range of photosynthesis and respiration rates, with little influence from overlying water conditions. Regardless of overlying water pH levels (from 7.

In situ detection of bacteria in calcified biofilms using FISH and CARD-FISH.

Modified protocols of fluorescence in situ hybridization (FISH) and catalyze reporter deposition fluorescence in situ hybridization (CARD-FISH) were developed in order to detect bacteria in situ in calcified stromatolite biofilms. Smooth, well-preserved thin sections of calcified biofilms (approximately 5 microm thin, vertical sectioning of approximately 1 cm deep) were obtained by cryo-sectioning using the adhesive tape-stabilization technique. A modified hybridization buffer was applied during hybridization to prevent calcite dissolution as well as false binding of oligonucleotide probes to the charged mineral surfaces.