Research works on the removal of mercury from water by zeolitic mineralshow that small quantities of this element are sorbed. In this work the mercury sorption from aqueous solutions in the presence and absence of Cu(II), Ni(II) and Zn(II) onto a Mexican zeolitic mineral unmodified and modified with cysteamine hydrochloride or cystamine dihydrochloride was investigated in acidic pH. The zeolitic minerals were characterized by thermogravimetric analysis, scanning electron microscopy, X-ray diffraction and FTIR. The sorption kinetics behavior and the retention isotherms for mercury were determined in the natural and treated zeolitic mineral samples. It was found that the amounts of sulfur on the modified zeolitic minerals were 0.375 (cysteamine hydrochloride) and 0.475 (cystamine dihydrochloride) mmol g⁻¹, which were not saturated to their total capacities of adsorption for the maximum concentration used (0.310 mM). Under the experimental conditions, the retention of mercury was the highest for the zeolitic minerals treated with the organic compounds, with adsorption capacities ranging from 0.0107 to 0.0509 mmol Hg g⁻¹.The retention was not affected by the presence of others heavy metals studied in this work as expected.

The adsorption characteristics of heavy metals: cadmium(II), chromium(III), copper(II), nickel(II), lead(II), and zinc(II) ions by kaolin (kaolinite) and ballclay (illite) from Thailand were studied. This research was focussed on the pH, adsorption isotherms of single-metal solutions at 30–60 °C by batch experiments, and on ion selectivityin mixed and binary combination solutions. It was found that, except Ni, metal adsorption increased with increased pH of the solutions and their adsorption followed both Langmuir and Freundlich isotherms. Adsorption of metals in the mixture solutions by kaolin was: Cr > Zn > Cu ≈ Cd ≈ Ni > Pb, and for ballclay was: Cr > Zn > Cu > Cd ≈ Pb > Ni. The adsorption of metals was endothermic, with the exception of Cd, Pb and Zn for kaolin, Cu and Zn for ballclay. Kaolin and ballclay exhibited relatively hard Lewis base adsorption site. The presence of other metals may reduce or promote the adsorption of heavy metals. The presence of Cr³⁺induced the greatest reduction of metal adsorptiononto kaolin, as did the presence of Cu²⁺for ballclay.

Urban transportation activities generate a wide gradation of anthropogenic solids with varying physical and chemical properties. These solids accumulatein urban highway snow and remain as residual deposition material after the melting and recession of the snow from the pavement shoulder. This study analyzed the physical characteristics of these residuals and the associatedheavy metals for 10 urban highway sites located throughout metropolitan Cincinnati. Results from the residuals analyses indicate that for all sites particle gradations ranged from greater than 5000-μm to less than 25-μm with a mean d₅₀of 1225-μm. Specific gravity (ρₛg) of residual solids ranged from 2.5 to 3.2 as evaluated for intervals across thegradations, with the lower specific gravity associated with particles less than 100-μm. For each gradation, specific surface area (SSA) generally increased with decreasing particle size while the predominance of total surface area (SA) was associated with the coarser size fractions. Cumulativeanalysis for Pb, Cu, Cd and Zn associated with snow residuals indicated that more than 50% of the heavy metal mass was associated with particles greaterthan 250-μm and more than 80% was associated with particles greater than 50-μm. Results provide guidance for management of urban snow residuals and design of treatment strategies focused on these residuals.

We studied the environmental effects of the mining activity of Troya Mine on the fluvial ecosystem, in the Basque Country, Spain, from 1993 to 1995. The multivariate analysis of the physicochemical conditions shows that the main abiotic factors of variation are: (i) in the water column, a significant increase in the content of heavy metals and conductivity, and (ii) an intense accumulation of heavy metals in the bottom sediments. We studied the effects of these factors on density, richness, dominance, similarity coefficient and composition of the benthic macroinvertebrate community (BMI).We observed a de-structuring of the community. Richness decreases (from 25 to 11 different number of families), but it does not suitably value the impact. Density oscillates radically (255–1548 individuals m⁻²) and reflects changes occurred in sediments. Dominance, which oscillates from 0 to 1, increase from 0.16 upstream from the mine, to 0.42 downstream, fundamentally due to oscillations of Chironomidae, Tubificidae, Baetidae and Simuliidae. The similarity coefficient indicates the physicochemical variations both in the sediment and in the water column; this index is therefore suitable for the follow-up of the evolution of the disturbance studied. The families sensitive to disturbance in the water column are: Ephemeridae, Athericidae, Sericostomatidae, Leptophlebiidae, Baetidae, Gammaridae, Perlidae, Heptageniidae, and Leptoceridae; the tolerant ones are: Coenagrionidae, Hydrobiidae, Lumbricidae, and Polycentropodidae.With regard to the metal content in sediments, the sensitive families are: Gammaridae, Ephemeridae and Ceratopogonidae; the tolerant ones are: Simuliidae, Culicidae, Hydrophilidae, Dolichopodidae, Chironomidae, Psychodidae, Tipulidae, and Chrysomelidae.We thus synthesized the complexity inherent to this type of pollution, in which large amounts of variables are normally involved.

More than 600 arable soils from Flanders (Northern-Belgium) were analysed for their total acid extractable contents of As, B, Be, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in order to determine any increase in the natural background values. Samples were taken at random in several municipalities throughout Flanders. Areas with known historical or actual sources of trace element emissions were omitted although in some cases the distance between those sources and the sampling locations was not more than 20 km. The main soil types were, ranging from north to south: sand, loamy sand, light sandy-loam, sandy-loam and loam. In the coastal area, clay soils (sea polders) were sampled. In addition to the analysis of trace elements, the soil texture class, the pH and the carbon content were determined. Macro- or mesonutrients, Ca, K, P, Mg and Na, were determined from a weak acid extract of the soil samples. Correlations between trace elements and macronutrients provide some information about fertilisation practices and heavy metal sources.A limited number of soils showed slightly enhanced levels for As, Be, Cu, Co, Cr Mn, Ni Pb and Zn. In most cases, this could be linked to the regional industrial activities. However, a clear increase for Cu and Zn, above the natural background could be distinguished in areas with low atmospheric heavy metal deposits. In these cases, the excessive use of animal manure in the past may be the reason for this enrichment. However there was no indication that the Cd content of the soil was raised by the use of large amounts of pig slurry and/or by other common agricultural activities.