Metals in SURFACE WATER of Ukraine: the migration forms, features of distribution between the abiotic components of aquatic ecosystems, and potential bioavailability
We have generalized the results of long-term studies of coexisting forms of a series of metals (Al, Fe, Mn, Zn, Cu, Cr, Pb, Mo, Cd, and V) in surface water bodies of Ukraine, differing in the hydrological regime and the water chemical composition (rivers, reservoirs, lakes, and ponds). The studied metals content has ranged widely, the concentrations of aluminum, iron, and manganese being typically the highest, and the concentration of molybdenum, vanadium, and cadmium being typically the lowest.
The ratio between the suspended and the dissolved forms of the metals has been established.
Iron and aluminum migrate mostly as part of the suspended matter, whereas the other metals mainly migrate in the dissolved state.
The dissolved manganese form predominates in the water bodies under anaerobic conditions.
Copper and molybdenum are present almost always in the dissolved state, regardless of the water body type.
The data on the relative content of the labile metal fraction (potentially toxic to aquatic organisms) are reported. The relatively low content of this fraction has been found to be majorly owing to the metal ions complexing with natural organic ligands. The humic compounds, the most widespread group of natural organic compounds, play the primary role in the complexation. Even metals with variable oxidation state (Cr, Mo, and V) are found mainly in the form of anionic complexes with the humic substances. Carbohydrates are also involved in the metals binding in the highly bioproductive water bodies, thus increasing the mass fraction of the neutral complexes during the summer and autumn periods.
The molecular weight distribution of anionic metal complexes has been discussed; the substantial part of the metals constitutes the compounds with the molecular weight of below 5.0 kDa.
Linnik, P. N., Zhezherya, V. A., Linnik, R. P., Ignatenko, II, and Zubenko, I. B.,Metals in surface water of Ukraine: the migration forms, features of distribution between the abiotic components of aquatic ecosystems, and potential bioavailability, Russian Journal of General Chemistry, 2015, 85, 2965-2984.
Molybdenum and zinc stable isotope variation in MINING WASTE rock drainage and waste rock at the Antamina mine, Peru
The stable isotope composition of molybdenum (Mo) and zinc (Zn) in mine wastes at the Antamina Copper-Zn-Mo mine, Peru, was characterized to investigate whether isotopic variation of these elements indicated metal attenuation processes in mine drainage.
Waste rock and ore minerals were analyzed to identify the isotopic composition of Mo and Zn sources, namely molybdenites (MoS2) and sphalerites (ZnS). Molybdenum and Zn stable isotope ratios are reported relative to the NIST-SRM-3134 and PCIGR-1 Zn standards, respectively.
Delta98Mo among molybdenites ranged from -0.6 to +0.6 per thousand (n=9) while sphalerites showed no delta66Zn variations (0.11+/-0.01 per thousand, 2 SD, n=5).
Mine drainage samples from field waste rock weathering experiments were also analyzed to examine the extent of isotopic variability in the dissolved phase. Variations spanned 2.2 per thousand in delta98Mo (-0.1 to +2.1 per thousand) and 0.7 per thousand in delta66Zn (-0.4 to +0.3 per thousand) in mine drainage over a wide pH range (pH2.2-8.6).
Lighter delta66Zn signatures were observed in alkaline pH conditions, which was consistent with Zn adsorption and/or hydrozincite (Zn5(OH)6(CO3)2) formation. However, in acidic mine drainage Zn isotopic compositions reflected the value of sphalerites.
In addition, molybdenum isotope compositions in mine drainage were shifted towards heavier values (0.89+/-1.25 per thousand, 2 SD, n=16), with some overlap, in comparison to molybdenites and waste rock (0.13+/-0.82 per thousand, 2 SD, n=9).
The cause of heavy Mo isotopic signatures in mine drainage was more difficult to resolve due to isotopic heterogeneity among ore minerals and a variety of possible overlapping processes including dissolution, adsorption and secondary mineral precipitation.
This study shows that variation in metal isotope ratios are promising indicators of metal attenuation. Future characterization of isotopic fractionation associated to key environmental reactions will improve the power of Mo and Zn isotope ratios to track the fate of these elements in mine drainage.
Skierszkan, E. K., Mayer, K. U., Weis, D., and Beckie, R. D.,Molybdenum and zinc stable isotope variation in mining waste rock drainage and waste rock at the Antamina mine, Peru, The Science of the total environment, 2016, 550, 103-113.
GROUNDWATER Molybdenum from Emerging Industries in Taiwan
This study determined the influence of emerging industries development on molybdenum (Mo) groundwater contamination.
A total of 537 groundwater samples were collected for Mo determination, including 295 samples from potentially contaminated areas of 3 industrial parks in Taiwan and 242 samples from non-potentially contaminated areas during 2008-2014.
Most of the high Mo samples are located downstream from a thin film transistor-liquid crystal display (TFT-LCD) panel factory.
Mean groundwater Mo concentrations from potentially contaminated areas (0.0058 mg/L) were significantly higher (p < 0.05) than those from non-potentially contaminated areas (0.0022 mg/L). The highest Mo wastewater concentrations in the effluent from the opto-electronics industry and following wastewater batch treatment were 0.788 and 0.0326 mg/L, respectively. This indicates that wastewater containing Mo is a possible source of both groundwater and surface water contamination. Nine samples of groundwater exceed the World Health Organization's suggested drinking water guideline of 0.07 mg/L. A non-carcinogenic risk assessment for Mo in adults and children using the Mo concentration of 0.07 mg/L yielded risks of 0.546 and 0.215, respectively.
These results indicate the importance of the development of a national drinking water quality standard for Mo in Taiwan to ensure safe groundwater for use.
According to the human health risk calculation, the groundwater Mo standard is suggested as 0.07 mg/L. Reduction the discharge of Mo-contaminated wastewater from factories in the industrial parks is also the important task in the future.
Tsai, K. S., Chang, Y. M., Kao, J. C. M., and Lin, K. L.,Groundwater Molybdenum from Emerging Industries in Taiwan, Bulletin of Environmental Contamination and Toxicology, 2016, 96, 102-106.
Acid extraction of molybdenum, nickel and cobalt from MINERAL SLUDGE generated by rainfall water at a metal recycling plant
This study investigated the leaching yields of Mo, Ni and Co from a mineral sludge of a metal recycling plant generated by rainfalls.
The investigated mineral sludge had a complex heterogeneous composition, consisting of particles of settled soil combined with metal-bearing particles (produced by catalysts, metallic oxides and battery recycling).
The leaching potential of different leaching reagents (stand-alone strong acids (HNO3 (68%), H2SO4 (98%) and HCl (36%)) and acid mixtures (aqua regia (nitric + hydrochloric (1:3)), nitric + sulphuric (1:1) and nitric + sulphuric + hydrochloric (2:1:1)) was investigated at changing operational parameters (solid-liquid (S/L) ratio, leaching time and temperature), in order to select the leaching reagent which achieves the highest metal leaching yields. Sulphuric acid (98% H2SO4) was found to be the leachant with the highest metal leaching potential.
The optimal leaching conditions were a three-stage successive leaching at 80 degrees C with a leaching time of 2 h and S/L ratio of 0.25 g L-1. Under these conditions, the achieved mineral sludge sample leaching yields were 85.5%, 40.5% and 93.8% for Mo, Ni and Co, respectively.
The higher metal leaching potential of H2SO4 in comparison with the other strong acids/acid mixtures is attributed to the fact that H2SO4 is a diacidic compound, thus it has more H(+) ions, resulting in its stronger oxidizing power and corrosiveness.
Vemic, M., Bordas, F., Guibaud, G., Comte, S., Joussein, E., Lens, P. N., and Hullebusch, E. D.,Acid extraction of molybdenum, nickel and cobalt from mineral sludge generated by rainfall water at a metal recycling plant, Environmental technology, 2016, 37, 630-9.
Binding and leaching of trace elements in PORTLAND CEMENT pastes
Portland cement contains trace elements originating from the raw materials and the fuels used for cement production. The trace elements are bound to some extent during cement hydration. A small fraction remains dissolved in the pore solution. The dissolved fractions of antimony, barium, chromium, lead, molybdenum and vanadium were quantified in the course of hydration of four different Portland cements. The development of heavy metal concentrations signifies the relevant hydration products for the binding of heavy metals. For chromate and molybdate a substitution for sulfate in ettringite was found. Vanadium and antimony are most likely not bound in ettringite. Barium precipitates as barium sulfate. For lead no clear trends could be observed. Leaching experiments were carried out and the concentrations of the leachates were compared to pore solution concentrations to check if the solubility of the heavy metals is relevant or if the leaching process is controlled by diffusion. (C) 2015 Elsevier Ltd. All rights reserved.
Vollpracht, A., and Brameshuber, W.,Binding and leaching of trace elements in Portland cement pastes, Cement and Concrete Research, 2016, 79, 76-92.