Anionic species of V, As, Se, Mo, Sb, Te and W in the Scheldt and Rhine estuaries and the Southern Bight (North Sea)

Correlation of burial organic carbon and paleoproductivity in the Mesoproterozoic Hongshuizhuang Formation, northern North China

“…In oxygenated envrionments, V 5+ is found in the form of vanadate [40], however, under anoxic or euxinic environments, V 5+ is reduced to form VO(OH) 2 or organometallic ligands or vanadium porphyrin or V 2 O 3 or V(OH) 3 which then can be enriched in the sediment [41][42][43][44][45][46]. Under oxic seawater, Cr is present mainly as Cr 4+ in the chromate anion [47]; however, in anoxic circumstances, Cr 4+ is reduced to Cr 3+ which is mainly enriched in the sediment as Cr 2 O 3 or Cr(OH) 3 or complexation with humic/fulvic acids or adsorption on Fe-and Mn-oxyhydroxides [48,49].…”

Molybdenum and tungsten in volcanic rocks and in surface and <100°C ground waters in Iceland

“…Reported Mo and W concentrations in surface waters are generally below 1 and 0.1 ppb, respectively, but may be as high as 30 and 6 ppb (Krauskopf, 1974;Manheim and Landergren, 1974;Kaback and Runnells, 1980;Van der Sloot et al, 1985;Konhauser et al, 1997;Johannesson et al, 2000). Geothermal waters and surface and ground waters in areas of Mo and W deposits are typically higher in both elements, as high as 70 ppb for Mo (e.g.…”

Inhibition of mercury methylation in anoxic freshwater sediment by group VI anions

“…Despite the fact that Te concentrations may be high in aquatic systems surrounded by Te‐rich geologic materials affected by geochemical weathering reactions or in systems impacted by anthropogenic activities, Te exists in most aquatic environments in concentrations below 0.6 nM [21]. Accordingly, a substantial inhibitory effect of tellurium on MeHg formation is unlikely in most natural systems.…”