CHEMICAL SPECIATION IN SOLUTION AND SUSPENSION OF METAL POLLUTANTS AND AS IN WATERS, CONTAMINATED BY METALLURGICAL AND MINING ACTIVITIES

3rd International Scientific Conference - SGEM2003, www.sgem.org, SGEM2003 Conference Proceedings/ ISBN: 954-918181-2, June 9-13, 2003, 277- 286pp

ABSTRACT

Chemical species of existence and migration of water metal pollutants in
solution and suspension in the significantly contaminated Plovdiv – Assenovgrad
area are identified in their dynamics. Underground, surface and technological
waters in their geochemical context are investigated (more than 2 000 data) as a
ground of the speciation study (30 trace and 24 major elements). All the trace
elements analytical researches are carried out by HR-ICP-AES Jobin Yvon
ULTIMA 2 and the speciation study – by WATEQ 4F adapted program. About 60
chemical species for the heavy metal + As pollutants in every water are proved,
about 40 – for the major components. 3D-presentation and juxtaposition, priority
ranges and respective interpretation for every metal pollutant, As, and the major
compounds are effected. For ex. Cd appears the pollutant with the most
pronounced speciation differentiation in function of the water type. In the ground
waters a generalized rate for the Pb forms importance could be presented as
follows: PbCO3>PbHCO3
 >Pb(CO3)2
2->Pb2+>PbSO4>PbOH+>Pb(SO4)2
2- and for
Zn: Zn2+>ZnHCO3
+> ZnCO3>ZnSO4>Zn(SO4)2
2->Zn(CO3)2
2->ZnOH+>ZnCl+. In
surface waters only different carbonate species predominate as in waste waters
(together with hydroxide and sulfate forms). The presence in solution of heavy
metal mobile forms and their secondary modification are ensured by the
complexation and to the good migration ability of a pronounced diversity of
established chemical species, with different relative weight and accumulation
possibilities. The migration form mobility, controlled by about than 200 mineral
phases, more or less near to equilibrium, is very distinguished for ground and
surface waters. The oversaturation is found to be typical for the more polluted
waters. The separated on membrane filter 0.45 μm suspended matter in the studied
waters is very abundant and the Electron Microprobe Analysis investigations
identify various mineral and chemical forms and paragenesises. In technological
water suspension twenty trace elements are established (Hg, Ta, Se, Y in between)
and Zn, Fe, Pb, Cu oxides determine the composition. Suspended matter in some
polluted ground waters is characterized by a composition like: 50% ZnO, 4% PbO,
24% SiO2, 6%Al2O3, 9% FeO, 1% BaO, 1% K2O, 4% CaO, 0,2 % MgO, 0,5 %
MnO, 0,4 % CuO and 0,2% TiO. The chemical speciation analysis of individual
suspended matter particles (500) using EPMA, is very good differentiated in
function of the pollution quality characteristics: a) Zn together with Mn and Fe is
included mainly in Al-Si-Fe (or Fe-Si and Al-Zn) particles in polluted ground
waters (where the most important particle size is registered); b) in quarry lake
water Al-Ca-Cl particles are enriched with Mn, Fe, P, S; c) in non polluted ground
waters only Fe and Al (and some Mn) are identified in Al-Si, Fe-Si and Al-Fe rich
particles. The present and future state of the dynamic equilibrium between the
different species in solution and suspension (defining the biological and toxical
activity of the pollutants) are so elucidated and the definitive hydrogeochemical
characteristics of the waters with possibilities for preservation and forecasting of
their evolution are suggested. The investigations are financed by the Bulgarian
budget of the NATO Science for Peace Program Project NATO SfP 973 739
“WATMETAPOL”.