Mining-impacted sediments of Lake Coeur d'Alene, Idaho, contain more than 10% metals on a dry weight basis, approximately 80% of which is iron. Since iron (hydr)oxides adsorb toxic, ore-associated elements, such as arsenic, iron (hydr)oxide reduction may in part control the mobility and bioavailability of these elements. Geochemical and microbiological data were collected to examine the ecologi...

Iron (Fe) oxides exist in a spectrum of structures in the environment, with ferrihydrite widely considered the most bioavailable phase. Yet, ferrihydrite is unstable and rapidly transforms to more crystalline Fe(III) oxides (e.g., goethite, hematite), which are poorly reduced by model dissimilatory Fe(III)-reducing microorganisms. This begs the question, what processes and microbial groups are ...

Metallic iron (Fe) is often reported as a reducing agent for environmental remediation. There is still controversy as to whether Fe plays any significant direct role in the process of contaminant reductive transformation. The view that Fe is mostly a generator of reducing agents (e.g. H, H2 and Fe) and Fe oxyhydroxides has been either severely refuted or just tolerated. The tolerance is based o...

Background: Autoxidation is considered to be the main route of edible oil deterioration, which produces undesirable odors and flavors (attributed to primary and secondary products of unsaturated fatty acids) during storage and heating. Objective: Antioxidant activities of Zataria multiflora (ZMEO) and Bunium persicum (BPEO) essential oils (EOs) in linseed oil (containing higher ω-3 in vegetab...

The essential oils and aromatic water, known as Arak in traditional Iranian medicine, comes from the aerial part of Teucrium persicum Boiss., which is grown in Fars Province located in Iran. The samples were collected in summer and the oils and aromatic water were obtained through steam distillation. The chemical composition of the oils was analyzed using GC-MS. An analysis of the chemical prof...

Cissus populnea are plants associated with a myriad of medicinal uses in different parts of the world and are good sources of carotenoids, triterpenoids, and ascorbic acid. The antioxidant properties and inhibitory effect of water extractible phytochemicals from stem bark of C. populnea on FeSO(4) and sodium nitroprusside- (SNP-) induced lipid peroxidation in rat testes were investigated in vit...

A chromatographic method was developed for simultaneous determination of Fe(III), Fe(II), Mn(II), and other transition metals. A high-performance polymer-coated silica-based cation exchange column was used for the separation of metals from hydrochloric acid-extracted environmental samples. After separation, the metals were mixed with PAR [4-(2-pyridylazo)resorcinol] and passed through a superco...

The iron mining regions of Brazil contain thousands of “iron ore caves” (IOCs) that form within Fe(III)-rich deposits. The mechanisms by which these IOCs form remain unclear, but the reductive dissolution of Fe(III) (hydr)oxides by Fe(III) reducing bacteria (FeRB) could provide a microbiological mechanism for their formation. We evaluated the susceptibility of Fe(III) deposits associated with t...

Many physical and chemical processes control the extent of Fe(III) oxyhydroxide reduction by dissimilatory Fe(III)-reducing bacteria. The surface precipitation of secondary Fe minerals on Fe(III) oxyhydroxides limits the extent of microbial Fe(III) reduction, but this phenomenon has not yet been observed in nature. This paper reports the observation of secondary Fe-mineral (goethite) encrustati...

Chestnut shell melanin can be used as a colorant and antioxidant, and fractionated into three fractions (Fr. 1, Fr. 2, and Fr. 3) with different physicochemical properties. Antioxidant activities of the fractions were comparatively evaluated for the first time. The fractions exhibited different antioxidative potential in different evaluation systems. Fr. 1, which is only soluble in alkaline wat...