A methodological framework to study the behavior and kinetic influence of V, Mn, Co, Ni, Cu, Zn, As, Se and Mo during pyrite formation via the polysulfide pathway at ambient temperature

Pyritization links the biogeochemical cycles of Fe, S and C to those trace elements (TE) such as As, Ni, Cu, Co, Mn, Zn, Se Mo in reducing environments. The scavenging modes impurities pyrite are parameters importance for evaluating which extent can immobilize TE under diverse (sub)surface conditions. Furthermore, determining fate during pyritization is a prerequisite evaluate ability record chemical signature surrounding waters at time precipitation. Here, we provide methodological framework study incorporation reaction sequence leading formation via polysulfide pathway. Laboratory syntheses were conducted by reacting FeS precursor with elemental sulfur – both readily obtained FeCl3 Na2S solution strict anoxia ambient temperature presence aqueous V, TE/Fe molar ratio 0.5 mol%. Within this simplified framework, our experiments aimed reproducing early water column aggregates/bottom sediments before late diagenetic aging phases. Solids liquids sampled over formation, up 3100 h, further analyzed ICP-OES, XRD, XRF STEM-EDXS obtain information on (1) kinetics (2) solid phase, after complete conversion FeS2. Pyrite kinetic observed be strongly influenced identity added TE, delay nucleation decreasing order Ni >> Co > Control, V Mo. During full sequence, i.e. plus S(0) FeS2, Mn remains liquid quickly precipitate remain sequestered overtime, Zn released into solution, As partially incorporated solid. Elemental mapping microscale using show that, except associated pyrite. Moreover, while homogeneously distributed particle scale Se, Ni-pyrite exhibited an enriched core. solid-liquid partition coefficients each model system calculated ranks follows: Cu ? Mn. These partitions discussed light values reported literature from natural settings. important differences exemplify complexity predict pyrite-water sedimentary environments, particular when considering additional multifactorial processes local biogeochemistry micro-environments, well partial sequestration non-sulfide minerals authigenic clays carbonates.