Content Of Hazardous Elements Research Articles

Effects of water-coal interactions on coal mine water quality in China: a lixiviation experiment and actual water quality investigation.

Water-coal interactions are dominant factors that affect water quality in coal mines. Using lixiviation, the effects of water-coal interactions on pH, salinity, and hazardous elemental enrichment in coal mine water and associated trends were simulated and analyzed. The salinity and hazardous element contents were low in the alkaline solution filtrate. However, the salinity and contents of hazardous elements (As, Cr, Zn, Cu, Mn, Co, Ni, Cd, Pb, U, and Be) in acid solution filtrate increased significantly with a decrease in pH. The pH of the solution filtrate was affected by the mineral composition of the coal, wherein the pyrite content could generally determine the pH. In addition, the spatial distribution and utilization potential of coal mine water quality in China was determined based on water quality data surveys. For water-deficient regions in northern China, particularly in the northwest, the local mine water had high salinity, a high pH, and a low content of hazardous elements; therefore, the reuse of mine water for water consumption is feasible. Conversely, the mine water in the southwest region had high salinity and a low pH and was enriched in harmful elements with potential ecological and health risks. The actual water quality characteristics of the coal mine water matched the results of the laboratory simulation analysis, confirming the effect from water-coal interactions. This work provides a reference for understanding the determinants of coal mine water quality and the potential for water environment protection.

Treatment of recycled rubber crumb to reduce content of hazardous elements

One of the major trends in material science consists of the reuse of various waste and by-products in order to reduce the environmental load associated with extensive landfilling and other waste disposal scenarios. Specifically, disposal of end-of-life tires and related reuse of this durable material represents a major issue for modern society. In this regard, various attempts can be recognized in the available literature. However, the production of tires is related to the use of various hazardous compounds such as heavy metals and polycyclic aromatic hydrocarbons in particular. These pollutants have an adverse effect not only on the natural environment but also on human health. On this account, the present paper deals with the treatment of rubber crumb as a possible way how to mitigate the environmental and health risk. Methods including the acid washing and hot-air scrubbing are employed with different duration to access the efficiency of the procedure. Presented results based on acid washing and hot-air treatment show a significant reduction below 10 mg/kg in polycyclic aromatic hydrocarbons content compared to untreated material (57 mg/kg). Consequent utilization of treated rubber crumb in the concrete as the aggregate replacement is not accompanied with increased reduction of mechanical properties compared to conventional rubber crumb. Namely, the reduction in strength was linear up to 30 wt% replacement of natural aggregate and further increase in the replacement ratio did not result in substantial deterioration in strength. Based on the obtained results, the described treatment procedure should be more broadly employed to avoid undesired consequences on human health as well as natural environment.

The evaluation of hazardous element content in the needles of the Norway spruce (Picea abies L.) that originated from anthropogenic activities in the vicinity of the native habitats

The aim of this research was to quantify the content of hazardous elements in the needles of Norway spruce (Picea abies L.) in the natural habitats that were accumulated from thermal power plants, mines, and metal processing industry. Fifteen natural populations of the Norway spruce were sampled from the mountain ranges in Southeastern Europe (Dinaric Alps and Balkan Mountains). Two-year-old spruce needles were evaluated the content of the following hazardous elements: heavy metals cadmium, mercury, nickel, lead and zinc, and metalloid arsenic. The effect of the distance between air pollution emitters and the Norway spruce natural habitats on the hazardous elements content in needles was also evaluated. The results of the analysis of variance confirmed interpopulation differences in the content of all analyzed hazardous elements. The effect of the air pollution source (thermal power plants, mines, and industry) on the content of hazardous elements in the spruce needles was also assessed. Significant correlation was found between the distance of air pollution emitters and the amount of zinc. This study could serve as the startup point of future monitoring programs and provide new prospect of using Norway spruce needles as the bioindicator of air pollution with hazardous elements on Balkan Peninsula since the fact that the Norway spruce natural populations inhabit wide geographic range of the continental Europe, from the Balkan Peninsula, over European Alps to Scandinavia and a large-scale of altitude from 980 to 1860m above sea level.

Glass beads for road markings and other industrial usage: Crystallinity and hazardous elements

Road markings, a necessary road safety feature, always contain a layer of glass beads that deliver retroreflectivity for driving at night and simultaneously protect the underlying paint layer. Even though such glass beads were generally considered as harmless, their analysis for the presence of crystalline silica was not reported so far. To fill the knowledge gap and to confirm the common perception, representative types of glass beads (11 samples from 6 manufacturing plants worldwide) were evaluated for the presence of crystalline phases by X-ray diffraction and their surface was analysed under scanning electron microscope. The study has not indicated the presence of a crystalline phase in amount higher than environmental background and no irregular shard-like surface features were found under microscope. In addition, analysis with inductively coupled plasma – mass spectrometry revealed only marginal content of hazardous elements. The same results were obtained with glass beads manufactured in identical process but used for other industrial applications. This assessment confirmed that the analysed classes of industrial glass beads are fully annealed and amorphous material that is free from hazardous ingredients.

The Effect of Ash Admixture on Compost Quality and Availability of Nutrients

The effect of graded doses of ash from biomass wood chips and straw admixture combustion on compost properties was investigated through a set of large-scale experiments. In a compost plant, matured organic composts were prepared from raw organic mixtures based on biodegradable waste, separated digestate, straw, and biomass ash admixture of 0, 3, 6, and 9 wt. %. Final composts, as well as individual components, were analyzed for basic physical and chemical properties, total and available nutrients, and potentially hazardous elements. Biomass ash addition increased the total nutrient content (P, K, Mg, Ca, and S) in the studied composts. The highest ash addition (9 wt. %) increased the nutrient content as follows: Ca (2.6×), Mg (1.6×), K (1.5×), P (1.2×), S (1.3×). However, the availability of some nutrients (especially P, K, and Mg) for plant nutrition was reduced by the increasing amount of ash admixture. Even at the highest dosage of biomass ash addition, desirable chemical (nutrient content) and physical properties of composts (especially dry bulk density) were both obtained. The content of hazardous elements was below the legal limit values in all studied composts.

Experimental Treatment of Hazardous Ash Waste by Microbial Consortium Aspergillus niger and Chlorella sp.: Decrease of the Ni Content and Identification of Adsorption Sites by Fourier-Transform Infrared Spectroscopy.

Despite the negative impact on the environment, incineration is one of the most commonly used methods for dealing with waste. Besides emissions, the production of ash, which usually shows several negative properties, such as a higher content of hazardous elements or strongly alkaline pH, is problematic from an environmental viewpoint as well. The subject of our paper was the assessment of biosorption of Ni from ash material by a microbial consortium of Chlorella sp. and Aspergillus niger. The solid substrate represented a fraction of particles of size <0.63 mm with a Ni content of 417 mg kg–1. We used a biomass consisting of two different organisms as the sorbent: a non-living algae culture of Chlorella sp. (an autotrophic organism) and the microscopic filamentous fungus A. niger (a heterotrophic organism) in the form of pellets. The experiments were conducted under static conditions as well as with the use of shaker (170 rpm) with different modifications: solid substrate, Chlorella sp. and pellets of A. niger; solid substrate and pellets of A. niger. The humidity-temperature conditions were also changed. Sorption took place under dry and also wet conditions (with distilled water in a volume of 30–50 ml), partially under laboratory conditions at a temperature of 25°C as well as in the exterior. The determination of the Ni content was done using inductively coupled plasma optical emission spectrometry (ICP-OES). The removal of Ni ranged from 13.61% efficiency (Chlorella sp., A. niger with the addition of 30 ml of distilled water, outdoors under static conditions after 48 h of the experiment) to 46.28% (Chlorella sp., A. niger with the addition of 30 ml of distilled water, on a shaker under laboratory conditions after 48 h of the experiment). For the purpose of analyzing the representation of functional groups in the microbial biomass and studying their interaction with the ash material, we used Fourier-transform infrared (FTIR) spectroscopy. We observed that the amount of Ni adsorbed positively correlates with absorbance in the spectral bands where we detect the vibrations of several organic functional groups. These groups include hydroxyl, aliphatic, carbonyl, carboxyl and amide structural units. The observed correlations indicate that, aside from polar and negatively charged groups, aliphatic or aromatic structures may also be involved in sorption processes due to electrostatic attraction. The correlation between absorbance and the Ni content reached a maximum in amide II band (r = 0.9; P < 0.001), where vibrations of the C=O, C–N, and N–H groups are detected. The presented results suggest that the simultaneous use of both microorganisms in biosorption represents an effective method for reducing Ni content in a solid substrate, which may be useful as a partial process for waste disposal.

Biomass fly ash as an alternative to coal fly ash in blended cements: Functional aspects

The tightening of environmental standards in the EU including the presupposed abatement of coal combustion power plants presents an important impulse towards the transition to a circular economy. However, the achievement of this challenging goal requires a solution to a number of problems. One of the downstream problems consists in the fact that the application of fly ash originating in coal combustion (CFA) as a partial cement replacement might be gradually abandoned in future decades. The first reason may be economical as the increasing environmental regulations will probably result in its more costly processing. The second one is related to the increasing use of alternative energy sources which can lead to the decreasing availability of CFA. Biomass fly ash (BFA) originating from wood combustion can be considered as one of the prospective environmentally more friendly candidates for a partial replacement of CFA as supplementary cementitious material (SCM). In this paper, functional aspects of a possible replacement of CFA by BFA in blended cements are analyzed. Complex characterization of BFA performed prior to the other investigations reveals very good prerequisites for its use as SCM. The experimental analysis of functional properties of Portland cement-BFA based composites after 28-days curing shows the suitability of BFA as SCM for the cement replacement up to 30% by mass. The data collected after 90 and 180 days of curing indicate a substantial improvement of strength of all analyzed composites. The significantly lower content of hazardous elements in BFA in a comparison with CFA presents another benefit; it can be used in blended cements without any further processing or treatment.

Functional, compositional, and regulatory analyses of imported and non-imported single dental crowns.

The aims of the study were to investigate functional and esthetic properties, the composition of the alloy, and the content of hazardous elements of single dental crowns with metal skeleton and fired porcelain. Epoxy models made from full mouth impressions taken of a patient with a crown preparation of the right maxillary first permanent molar were used for production of identical polyether impressions, which were distributed to dentists in Norway. The dentists sent the impressions to their regular dental laboratories. All 55 crowns collected were anonymized and examined. Of the crowns received, 35 were made in Norway, 12 were imported, and 8 were of unknown origin. The evaluation of functional properties revealed that 50% of the Norwegian, 42% of the imported, and 25% of the unknown-origin crowns were considered unacceptable. The composition of the alloy was not in accordance with that stated by the manufacturer for 17%, 13% and 20% of the crowns, where this information was provided. The lead content of the alloy exceeded the limit set by the ISO 22674: 2016 for 18% of the crowns in total. The statement that shall follow the work according to EU-regulations was not complete for approximately 75% of the works received.

Concentrating Mill Wastes are the Source of Pollution of Human Environment and Natural Ecosystems with Heavy Metals: A Case Study in Primorsky Krai, Russian Federation

Elevated contents of hazardous elements in natural ecosystems are often associated with human activities. Significant quantities of these elements, including heavy metals, are concentrated in tailings. The goal of the study was to assess the mineralogical and geochemical features of the old tailings of the decommissioned Krasnorechenskaya concentrating mill (located in Primorsky Krai, Russian Federation), which was processing complex tin-polymetallic and silver-lead-zinc ores, the chemical features of tailings pond waters, and the extent of environmental impact on the nearby Rudnaya river. In addition to the analysis of rock and water samples, the software modeling of the water-rock-gas system was carried out. In the study area, the minerals and rocks undergo changes that lead to the formation of highly mineralized, acidic waters saturated with various elements. In the tailings ponds, the maximum permissible concentrations were exceeded for Zn, Cd, Cu, Mg, Fetotal, Pb, Mn, Al, As, Co, Be, Sr, Ni, and Ba. The drainage from the tailings pond tripled the total mineralization of the Rudnaya river relative to the background values. However, the intoxication of the ecosystem by tailing products is partially inhibited by the secondary minerals in the tailings ponds. The negative impact is of a local nature, and 500 m downstream the concentration of many of the above elements is reduced. Despite this, the system that forms the chemical composition of highly mineralized waters is far from the equilibrium state. The oxidation of sulfides, dissolution of other minerals, and migration of oxidation and hydrolysis products will continue affecting the environment. In this regard, it is necessary to conduct environmental monitoring and undertake activities aimed at the recovery of mature concentration tailings or at suppressing the activity of hazardous elements by the conservation of tailings ponds.

Leaching of hazardous elements from Mozambican coal and coal ash

Large-scale coal mining is being carried out in Tete province, Mozambique. This area is also being planned to become a large coal fired power production hub serving electricity to neighboring countries in southern Africa. Thus, huge amounts of coal will be burned, resulting in the generation of a large quantity of coal ash. High concentrations of hazardous elements are often released from coal and coal ash causing negative impacts to human health and the environment. Therefore, it is important to understand the possibility of hazardous elements leaching. Aqueous batch leaching experiments under ambient conditions were conducted using six coal samples and their ash. Most of the coal leached very low concentrations of hazardous elements. However, an absence of carbonate minerals gave rise to higher acidity levels. This resulted in elevated leaching concentrations of manganese and iron, regardless of their contents. Burning coal resulted in higher contents of hazardous elements in the ash. However, leaching concentrations of most of the elements from the ash samples were still lower than the environmental standards. Chromium and manganese were enriched in slightly acidic leachates regardless of their contents while higher arsenic than the permitted level was leached from the ash containing the highest arsenic content that generated neutral pH leachate. These findings highlight a possibility of hazardous elements contamination from Mozambican coal and coal ash. Therefore, the storage of coal and disposal of coal wastes and ash in Tete Province should be done carefully and monitored to avoid the contamination in the region.

Characteristics of ash and slag from four biomass-fired power plants: Ash/slag ratio, unburned carbon, leaching of major and trace elements

The utilization of biomass energy is attracting worldwide attention due to the worsening energy crisis and the concerns on carbon dioxide emission. However, the rapidly development of biomass-fired power plants generate enormous amount of slag and ash. At present, the main treatment method of biomass slag and ash is landfill, which not only requires high cost, but also causes a series of environmental issues. Aiming at this problem, the slag and fly ash from four biomass power plants were sampled and characterized. The major/trace element composition and leaching characteristics of slag and fly ash are analyzed, and the effect of volatile mineral in these solid residues on furnace efficiency is also evaluated. The results indicate that for biomass-fired grate furnaces, in the generated solid residues, the slag accounts 60 ~ 70% while the fly ash accounts for 30 ~ 40%. The volatile elements in slag are much lower than those in fly ash, and the unburned carbon content of fly ash is generally lower than that of slag. Due to the enrichment of volatile minerals in fly ash, instead of 815 °C, 550 °C is suggested to measure the unburned carbon content in fly ash. When the measuring temperature of unburned carbon decreases from 815 °C to 550 °C, the measured energy loss from the incomplete combustion of solid fuels decreases by one third, which affords a more reasonable evaluation on combustion efficiency. The contents of cadmium and lead in certain fly ash samples exceed the standard, however, all fly ash samples have a high leaching rate of potassium but low leaching rates of copper, zinc, cadmium, lead, chromium and arsenic. It indicates that the fly ash from biomass-fired grate furnace is suitable for producing potassium fertilizer by leaching instead of direct soil fertilization or landfill. The leaching rate of most minerals in slag is much lower than that in fly ash and the contents of heavy metals are far below the prescribed upper limit in standard, which indicates that the slag from biomass-fired grate boiler is more suitable for direct use in soil improvement due to the low contents of hazardous elements.

Nitrogen, sulfur, chlorine containing pollutants releasing characteristics during pyrolysis and combustion of oily sludge

Pyrolysis and combustion have become effective technologies for oily sludge treatment. This paper firstly investigated N/S/Cl pollutants during pyrolysis and combustion of oily sludge in detail by thermogravimetry-mass spectrum (TG-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Combined with the distribution characteristics and contents of hazardous elements, the releasing routes were proposed. Three typical decomposition steps were observed: volatilization of water and little hydrocarbons below 200 °C, cracking of hydrocarbons approximately at 200–500 °C, transformation of inorganic compositions at the higher temperature. Double-direction transfer diffusion reaction model was employed with estimated apparent activation energy Ea of 41.97–66.59 kJ·mol−1 for pyrolysis and 52.02–62.42 kJ·mol−1 for combustion. The main pyrolytic products were alkanes and alkenes ranging from C9 to C21, which had the potential to be reused as diesel fuels. Slight amounts of S/Cl-containing species were detected in liquid products. Database of inorganic and organic N/S/Cl pollutants with larger molecules was established. Organic N/S/Cl functionalities in oily sludge contributed to the majority of N/S/Cl pollutants. NH3, HCN, HNCO, NO, NO2, CS2, SO2, CH3SH, HCl, and Cl2 were generated between 200 and 600 °C during pyrolysis process, which were much lower than the quantity of corresponding products from combustion. Oxygen-enriched atmosphere in combustion facilitated decomposition of organic fractions, and shifted release regions towards lower temperatures. The decomposition of amine-N functionality contributed to NH3 release below 200 °C. With temperature increasing, heterocyclic-N began to decompose and release abundant NH3, small amounts of HCN and HNCO. Aliphatic-S and disulfides-S contributed to the formation of H2S, COS, and CS2.

The Quality and Characteristics of Final Substrates from Different Composting Technologies

In industrial composting, a large scale of technological processes and devices is used which, to a certain extent, influence also the quality and characteristics of final substrates. Composts are, on the basis of the existing legislation, compared from the point of view of content of hazardous elements, qualitative characteristics, content and quality of humic substances, their impact on germination capacity and the subsequent growth of plants.

FOOD SAFETY ON HEAVY METALS OF VEGETATION SAMPLES FROM A ROUTE OF THE NORTHERN FLEET’S COMPLEXED EXPIDITION «NOVAYA ZEMLYA-2018»»

Introduction. In publications devoted to survival under conditions of autonomous existence, there is no information available on the contamination of natural food raw materials with heavy metals (HM). The prevalence of HM in the Arctic and the ability of some plants to their bioaccumulation necessitates studying the content of hazardous elements in samples of local flora.Purpose of the work: assessment of the potential hazard, based on the content of HM, the consumption of objects of the Arctic flora that grow at military training places and places of probable disembarkation of crews of ships being in distress in areas of the northern seas of the Russian Federation.Tasks: assessment of the content of HM in plants growing in the Arctic and comparison of the obtained data with the maximum permissible levels (MPE) established by current regulatory documents. Vegetation samples were collected on the territory of the Northern Island of Novaya Zemlya Archipelago, their species affiliation was determined and they were dried in the herbar press. The analysis was performed by means of atomic spectrometer MGA-915M. Statistical processing of the results was carried out using the software Statistica for Windows 7.0. It was found that the content of cadmium (Cd) in willow leaves exceeds manifold the maximum permissible concentration. In plants of other species, small excess of MPE by selected elements were found. The data obtained are discussed in the context of the exceptional ability of willow plants to accumulate HM, especially Cd. It is proposed to exclude arctic species of willow from the list of objects recommended for eating in conditions of autonomous existence. The other objects are not advisable to exclude. However, taking into account some excesses of MPC in a number of plants, the prevention of monophagy as well as the maximum possible diversity and alternation of plant species when used for food is strongly recommended for consummation of plants.

New Data and Evidence on the Mineralogy and Geochemistry of Wulantuga High-Ge Coal Deposit of Shengli Coalfield, Inner Mongolia, China

The mode of occurrence and origin of highly-enriched trace elements, especially Ge, in Wulantuga high-Ge coal deposit have been widely reported. In this study, coal samples and several coalified trunks embedded within the roof strata are collected, which provides a good opportunity to further confirm if Ge is mainly associated with organic matter. Minerals in coal samples are mainly quartz, kaolinite, montmorillonite, pyrite, and gypsum, along with trace albite, barite, chlorite, and Fe-oxide, while those in coalified trunk samples include melanterite, pyrite, and gypsum, with traces of chlorite and magnesiocopiapite. Germanium, As, W, Sb, Hg, Be, and Cs are enriched in coal samples, and these elements are also enriched in the coalified trunks and roof glutenite. The elevated contents of Ge, As, W, Sb, and Hg were almost exclusively derived from the influx of hydrothermal fluids as evidenced by the presence of pyrite veins and chamosite as well as enhanced elemental associations of Ge-W and As-Sb-Hg in the studied lignite samples. The coalified trunks in the study area should be taken into consideration due to the high contents of hazardous elements that cause potential environmental impacts during mining waste disposal and land reclamation.

Особенности химического состава речных раков

The cultivation of crayfish in the structure of aquaculture in the Middle Volga region can be an important component. Currently, natural crayfish populations in the Republic of Tatarstan include 2 species – narrow-toed crayfish (Pontastacus leptodactylus Esch.) and wide-toed crayfish (A. astacus L.). The development of aquabiological technologies allows the use of natural crayfish populations for the tasks of creating industrial breeding farms. In connection with the global trend of the growing popularity of crayfish in food use, the importance of research on the chemical composition of crayfish as objects of consumption grows. The chemical analysis of narrow-fingered crayfish revealed 13 elements, of which calcium is found in maximum amount in the dry residue. The calcium content in the narrow crayfish was 154.057 g/kg dry weight (fig. 1), the chitinous shell of crayfish contains relatively more calcium – up to 376.282 g/kg of dry weight. The following sequences of the content of chemical elements in crayfish from the Kuibyshev reservoir are noted:  in the muscle tissue of edible parts Ca ˃K ˃S ˃P ˃Cu ˃Fe ˃Zn ˃Mn ~ Br ˃Sr;  in the shell Ca ˃Si ˃P ˃S ˃K ˃Sr ˃Ti ˃Fe ˃Mn ˃Cu ˃Br ˃Zn ˃As. In crayfish from the Kuibyshev reservoir we studied, the raw muscle mass of the edible parts of the crayfish contained 88.80% of water, 10.28% of organic substances and 0.92% of mineral substances, and in the chitin-containing raw shells of crayfish, respectively, contained 59.2% of water, 36.42% organic matter and 4.38% mineral matter. The particular interest is the study of crayfish shells, since they consist mainly of chitin. It is a bearing polysaccharide for invertebrate, reaching 85% of the weight of the integuments. In the cuticle of arthropods, chitin forms composite complexes with proteins, pigments, calcium salts. In the composition of the shells of crayfish, 376.282 mg/kg dry mass of calcium is noted. In smaller quantities phosphorus, potassium, iron and zinc are noted. Titanium was found in crayfish shells in the amount of 1845 mg/kg dry weight and was not found in their muscle tissue and other aquatic organisms in the region. In the studied crayfish, the content of heavy metals in the wet mass was: Zn – 0.42 mg/kg; Cu 6.5 mg/kg; Fe – 1.39 mg/kg; Sr – 0.23 mg/kg. Residual amounts of zinc and copper in the muscular tissue of the edible parts of crayfish of the Kuibyshev reservoir are within the normal range. The content of hazardous elements (lead, arsenic, cadmium and mercury) in the crayfish from the Kuibyshev reservoir is within the sanitary and epidemiological norms, and in the Volga delta crayfish the lead content is exceeded.

Clean recycle and utilization of hazardous iron-bearing waste in iron ore sintering process

Applying recycled iron-bearing waste materials (RIM) into iron ore sintering process is the general disposal approach worldwide, while its use is still a thorny problem. Results showed that adding RIM increased contents of hazardous elements (K, Na, Pb, Zn, and Cl) in sinter product, and also enhanced emission concentration of PM2.5 in flue gas; increasing reaction temperature, and contents of CaO & coke breeze in raw mixtures improved hazardous elements removal. Based on these features, a novel method through granulating natural iron ores and RIM separately and distributing granulated RIM in bottom sintering layers was proposed for clean RIM cycle. When recycling 5% RIM, granulating RIM separately with higher contents of CaO and coke breeze removed hazardous elements effectively, the contents of which in sinter were reduced to comparable level of the case without RIM. Moreover, distributing RIM in bottom sintering layer reached intensive release of hazardous elements and PM2.5 during sintering, which reduced the flue gas volume needing purification by about 2/3. Through activated carbon purification, about 60% of PM2.5 comprised high contents of hazardous elements was removed. Novel technique eliminated the negative impact of RIM and has the prospect to reach clean recycle in sinter-making plants.

Study of detailed geochemistry of hazardous elements in weathered coal ashes

The geochemical changes and the behaviors of the hazardous elements during the weathering of coal ash are not well known despite the potential toxicity of the hazardous elements leached from the ashes. In this work, ashes disposed in ash ponds were collected from different depths to investigate the effects of weathering on the geochemical changes and the mobilities of hazardous elements. The mineral phases identified in ash samples are quartz, mullite, K-feldspar, magnetite, illite, and glass phase. The contents of most major ions such as Si, Al, and K are strongly correlated with the changes in the mineral compositions of the ashes. However, the decrease in Ca and increase in loss on ignition (LOI) values with depth at both sites are observed owing possibly to the weathering of ashes. Our results show that leaching of hazardous elements caused by saturation with sea water is very important for the mobility of hazardous elements. Sequential extraction experiments show that high contents of hazardous elements are in the residual fraction, particularly in the raw coal ashes. For weathered ashes, a higher fraction of hazardous elements, especially As is bound to iron and manganese oxides, which increases significantly with depth. This indicates that As can be easily leached owing to the concentrated As on the surfaces of ash grains. Moreover, it can be strongly sorbed on iron oxide and hydroxide or co-precipitated with them. Therefore, magnetite and weathering products such as iron hydroxide can reduce the toxicity of As and other hazardous elements leached out during weathering.

Field approach to mining-dump revegetation by application of sewage sludge co-compost and a commercial biofertilizer

An approach was devised for revegetation of a mining dump soil, sited in a semiarid region, with basic pH as well as Fe and Mn enrichment. A field experiment was conducted involving the use of co-compost (a mixture of urban sewage sludge and plant remains) along with a commercial biofertilizer (a gel suspension which contains arbuscular mycorrhizal fungus) to reinforce the benefits of the former. Four treatments were studied: unamended soil; application of conditioners separately and in combination. Pistachio, caper, rosemary, thyme and juniper were planted. We evaluated the effects of the treatments using soil quality (physicochemical properties, total content of hazardous elements, nutrient availability, microbial biomass and enzyme activities) and plant establishment indicators (survival, growth, vigor, nutrient content in leaves, nutrient balances and mycorrhizal root colonization). Thyme and juniper did not show a suitable survival rate (<50%) whereas 70–100% of the pistachio, rosemary and caper survived for at least 27 months. In unamended soil, plant growth was severely hampered by P, N, K and Zn deficiencies as well as Fe and Mn excess. Overall, the treatments affected the soil and plant indicators as follows: biofertilizer + co-compost > co-compost > biofertilizer > unamended. The application of co-compost was therefore essential with regard to improving soil fertility; furthermore, it increased leaf N and P content, whereas leaf Fe and Mn concentrations showed a decrease. The combined treatment, however, provided the best results. The positive interaction between the two soil conditioners might be related to the capacity of the biofertilizer to increase nutrient uptake from the composted residue, and to protect plants against Fe and Mn toxicity.

Immediate Impact of the Flood (Bohemia, August 2002) on Selected Soil Characteristics

In August 2002 extreme floods affected Bohemia a part of the Czech Republic, along Vltava and Labe rivers. After the flood had culminated, soil samples of arable and meadow soil (flooded and control-non-flooded) have been collected in the surroundings of the cities of Ceske Budějovice (CB, South Bohemia, the Vltava river, the upper flood stream) and Usti nad Labem (UL, the Labe river, the lower flood stream). Different parameters of arable soils have been affected more significantly than those of meadow soils. Soil texture e.g. has been shifted from sandy loam to loam (CB) and clay loam (UL). Organic carbon, total phosphorus and nitrogen contents have been increased as well as the content of some hazardous elements such as arsenic. A shift of soil pH from 6.1 to 4.8 has been noticed in CB and an opposite one from 5.1 to 7.1 was measured in UL. Available phosphorus decreased in CB by 56% while a four-fold increase was measured in UL. Chlorinated organic pesticides level was significantly reduced, but that of polycyclic aromatic hydrocarbons (PAH) increased up to the maximum values of legal limits. The UL arable soil also became heavily contaminated by PAH. The CB arable soil demonstrated high microbial activity, while UL arable soil suffered under stress conditions in this respect. The flooded meadow soils became covered with a layer of drifted soil sediment, which retained enhanced content of the PAH's different hazardous elements, and, in addition, the soil aeration was reduced.