In Zacatecas, Mexico, four plants are operating to extract Ag, Au, and Hg using CaS₂O₃solution from surface soil containing tailings from the amalgamation method used during 1550–1900. The metal ions extracted are cemented by scrap Cu wires. Hg is separated by evaporation from the cemented amalgam and Ag and Au are obtained from the residue. A part of the soil to be leached was separated and leached as in the industrial process. Only 121 ppm of Hg was freed from 168 ppm of extractable Hg. About a half of the remaining Hg in the soil evaporated during 18 months. This confirms that the Hg in the soil is metallic. Pb and As are also freed in the same process. It is estimated that 13 000–34 000 t of Hg had been discarded in the extraction of Ag.

The hydrochemistry of mountain lakes is highly conditioned by the chemicalcomposition of atmospheric deposition and by climate characteristics. Consequently these ecosystems have proved to be sensitive to long-term changes in both factors. Climate warming seems to be particularly pronounced in the Alpine region. A reduction of snow cover in space and time, due to less precipitation and higher temperatures, means a greater exposure of rocks and soils in the watersheds, which enhances weathering processes. In this paper we aim to evaluate the possible effect of these processes on long-term changes in the chemistry of alpine lakes. Recent climate changes affecting the study area were investigated through a data series referring to temperature, precipitation, snow depth and duration at some stations in the Ossola Valley. Chemical data of 35 lakes located in the Ossola and Sesia Valleys (Central Alps) were used. Lakes were sampled both in the late summer of 2000 and 2001 in the framework of two European Projects and the results compared with previous data (1984–1987). Two lakes (Boden Superiore and Inferiore, 2343 and 2334 m a.s.l., respectively), located in the northern part of the study area, have been sampled more or less continuously since the late 70s, enabling us to evaluate the trends of the main chemical variables. For lakes lying in catchments with highly soluble rocks, a comparison between the two data sets shows an increase of solute contents in the last few years. This result could be attributed to increased weathering rates due to climate warming.

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.

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.

In this study, the adsorption of phosphate on gas concrete from aqueous solutions has been studied as functions of temperature, mixing rates and suspension pH. Over 99% of phosphate removal was found. The chemical composition of the gas concrete has been defined by X-ray analysis. Experimental data was fitted to the Langmuir equation in order to Langmuir coefficients. After calculating Langmuir coefficients, adsorption free energy (Δ G⁰ₐdₛ.) has been determined. In order to gather information about adsorption mechanism, electrophoretic mobilites of particles were measured at various pHs by using Zeta meter 3.0+. It has been found that the adsorption is driven by the interactions between the ionizations of CaO and Al₂O₃and the formation of AlPO₄. According to the BET (N₂) measurements, the specific surface area of gas concrete was found as 22 m²g⁻¹. The surface area after adsorption has been found as 17 m²g⁻¹. The surface area covered by adsorbate has been found as 5.23 m²g⁻¹by usingaₛ= nˢₘ. aₘ. NA. These two areas determined by BET and Langmuir model were close to each other (BET: 22 m²g⁻¹–17 m²g⁻¹).

This paper is devoted to the assessment of the impact of the Upper Silesian Industrial Region on greenhouse gases emissions in Poland. Detailed analysis will cover emissions of methane and carbon dioxide which are characteristic for the mining and power engineering industry prevailing in this region. The industries of Silesia emit 16.2% of CO₂, and about 30% of methane emissions in Poland come from coal seams. The leading strategy to counteract this situation, not only in Upper Silesia, should involve the improved efficiency of energy use and decreased use of primary energy carriers.

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.

Bleached Kraft mill effluent was treated in an activated sludgereactor followed by an allophanic soil adsorption system (ASAS). Under aerobic conditions, removal efficiencies of biological oxygen demand (BOD₅) and chemical oxygen demand (COD) varied between 57.7–96.5% and 30.3–57.0%, respectively, depending on the hydraulic retention time (HRT). On the other hand, tannin-lignin and phenolic compounds removal efficiencies attained values between 13.2–51.2 and 3.6–33.5%,respectively. An allophanic soil adsorption system was designed for color and phenolic compounds removal. Three different types of soils were used: Natural allophanic soil as the control compared, with calcinated and acidified allophanic soil. The initial removal efficiencies for phenolic compounds varied between 72 an 87% for activated soils, while color initial removal efficiencies were between 95 and 99%. Moreover, COD and tannin-lignin initial removal efficiencies reached maximum values of 74 and 87%, respectively, for calcinated soil. Design parameters show that there is an enhancement factor in adsorption capacities for both activated soils. In fact, phenolic compounds breakpoint adsorption capacity increased 5.3 times for calcinated soil and 17.6 times for acidified soil, while saturation capacity increased between 2.2 and 3.2 times. In addition, color breakpoint adsorption capacity increased 2.8 times for calcinated soil and 10.4 times for acidified soil, while saturation capacity increased between 3.2 and 5.5 times.

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.

In this study, local air quality impacts of a proposed conventionalcoal-fired power plant in the İçel region has been investigated using numerical dispersion modeling studies coupled with a GIS application. Within the impact area of the facility, Industrial Source Complex Short Term (ISCST2) dispersion model has been used to estimate ground-level concentrations of air pollutants originating from the power plant. For the same impact area, GIS applications have been utilised to determine the agricultural yield distribution. For this purpose, relevant satellite images were digitised, classified and statistically analyzed. Based on the predicted ground-level pollutant concentrations and sensitivity of the agricultural crops to the pollutants, agricultural yield loss was estimated for the impact area.The results have been quantified and valuated in monetary terms for the purpose of performing an environmental cost benefit analysis. Comparison of the conventional cost benefit analysis with the environmental cost benefit analysis showed the significance of the external cost of the proposed facility, resulting from the environmental damages.