Manganese (Mn) is an essential mineral that is found at low levels in food, water, and the air. Under certain high-dose exposure conditions, elevations in tissue manganese levels can occur. Excessive manganese accumulation can result in adverse neurological, reproductive, and respiratory effects in both laboratory animals and humans. In humans, manganese-induced neurotoxicity (manganism) is the...

BACKGROUND Given mounting evidence for adverse effects from excess manganese exposure, it is critical to understand host factors, such as genetics, that affect manganese metabolism. METHODS Archived blood samples, collected from 332 Mexican women at delivery, were analyzed for manganese. We evaluated associations of manganese with functional variants in three candidate iron metabolism genes: ...

The removal of manganese and humic acid (HA) by two nanofiltration membranes, TFC-SR2 and TFC-SR3, was investigated in order to highlight the influence of speciation on manganese and HA retention. Manganese speciation and complexation with HA were modelled to understand how speciation could affect NF removal mechanisms. The behaviour of the two membranes was drastically different for manganese ...

We measured the manganese content of mononuclear blood cells and the manganese concentrations in whole blood and plasma from 31 healthy volunteers and 25 patients receiving total parenteral nutrition (TPN) (i.e., no dietary manganese). The manganese content (mean +/- 2 SD) of mononuclear blood cells and the manganese concentration in whole blood and plasma in the healthy volunteers were 8.84 +/...

In the Dusina area, which is built up of Lower Palaeozoic metasediments, Devonian carbonate complex and Upper Palaeozoic metarhyolites unconformably overlain by Upper Permian sediments, numerous ore occurrences have been investigated: (a) "stratabound" metamorphic hematite deposits in the pre-Devonian metasediments; (b) epigenetic veins and pipes of barite (& calcite) with accessory Hg-tetrahed...

BACKGROUND Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over severa...

Introduction Hydrothermal systems and their associated metal deposits have been studied at oceanic spreading centers since the late 1970s when they were first discovered. More recently, those studies have been extended to subduction zone hydrothermal systems including active volcanic arcs and back-arc environments. Oceanic spreading centers compose a global ridge system where new ocean crust is...

According to the publication by US Minerals Survey in 1999, the total reserve of manganese ore in the world is 0.66 billion tons. See Table 1. Table 1 World Manganese ore reserve(Mn metal weight, million tons) __________________________________________ Name of counties Reserve in 1999 __________________________________________ South Africa 370 Ukraine 135 China 40 India 34 Australia 26 Gabon 20...

Concerns exist as to whether individuals may be at greater risk for neurotoxicity following increased manganese (Mn) oral intake. The goals of this study were to determine the equivalence of 3 methods of oral exposure and the rate (mg Mn/kg/day) of exposure. Adult male rats were allocated to control diet (10 ppm), high manganese diet (200 ppm), manganese-supplemented drinking water, and mangane...

BACKGROUND Environmental manganese exposure has been associated with adverse neurodevelopmental outcomes among school-aged children; yet, few studies have evaluated prenatal exposure. OBJECTIVES Our study examines associations between prenatal manganese concentrations and placental transfer of manganese with neurodevelopment in 224 2-y-old children residing near the Tar Creek Superfund Site. ...