Redistribution Of Heavy Metals Research Articles

Accumulation of heavy metals in the vegetative organs of poplars under their joint introduction to the soil

Background. Studies of plant autecology under excessive heavy metal intake require a thorough understanding of the specifics of the uptake and accumulation of these substances by plants. It is therefore important to study the redistribution of heavy metals in the soil–plant system. Poplars, due to their rapid growth, large assimilative organ surface area, etc., are a suitable object for studying their autecological properties and potential use in the creation of green spaces. Materials and methods. The objects of the study were two-year-old poplar seedlings: ’I-45/51’, ’Lvivska’, ’Robusta’, ’Tronco’, and the soils on which they grow. The plants were watered once a week for 2 months with a mixture of heavy metal compounds at 1, 5, and 10 maximum permissible concentrations (MPC). Mixtures of the following salts were used as heavy metal sources CdSO4, Ni(NO3)2, CuSO4, ZnSO4, Pb(CH3COO)2. The control plants were not exposed to heavy metals. All plants were grown under natural light and temperature. The content of mobile forms of Cu, Zn, Ni, Pb, and Cd in ammonium acetic acid extract from soil was determined and their accumulation in leaves and roots was measured by conventional methods using a C-115PK atomic absorption spectrophotometer Selmi (Ukraine). Statistical proces­sing of the results was carried out using Microsoft Excel 2013. To assess the probability of the difference between the statistical characteristics of two alternative data sets, a univariate analysis of variance using IBM SPSS Statistics 27, ANOVA, was performed. Results. The accumulation and translocation of heavy metals in the soil–plant system was studied in model experiments. The study revealed the peculiarities of heavy metal accumulation in the soils where poplars grew. It was shown that the introduction of heavy metal compounds leads to an increase in the content of mobile forms of the studied elements in the soil. Under the influence of 1, 5, and 10 MPC of heavy metal ions, all cultivars accumulated them more actively in the root system than in the leaves. Conclusions. The studied poplars can be divided into two groups. The first one includes the cultivars ’I-45/51’ and ’Lvivska’ with a high level of heavy metal accumulation and the highest enrichment factor. The second group – ’Tronco’ and ’Robusta’ – includes those with low levels of heavy metal accumulation and low enrichment factors. The results suggest that the poplars of the second group have physiological mechanisms that determine the observed peculiarities of heavy metal translocation.

Bioaccumulation and Translocation of Heavy Metals in Solanum elaeagnifolium

Heavy metal pollution is becoming an increasingly common problem. Heavy metals including Chromium, Cadmium, Mercury, Copper, and lead are hazardous environmental pollutants, especially in high anthropogenic activity areas. Heavy metals accretion in soil is a serious concern for agricultural productivity due to its negative influence on food safety, market potential, and the phytotoxicity it causes in crops. Plant ascendancy and metabolic processes affect the geological and biological re-distribution of heavy metals through air, soil, and water pollution. The typical result of heavy metals toxicity is excessive accumulation of reactive methylglyoxal and oxygen species, which lead to lipid peroxidation, enzyme inactivation, nucleic acid damage, and protein oxidation in plants. In this study, bioaccumulation and Translocation of Heavy Metals in Solanum elaeagnifolium was conducted by using standard biological techniques. Twenty-four samples of both shoot and root systems collected ‎from the study sites and Three replications of soil samples from each habitat, including topsoil (0-50 cm depth) were studied.our results showed that the quantitative concentration of heavy metals in the shoots of S. elaeagnifolium for each metal indicated a high enrichment value for (Cr), (Fe), and (Mn), on the other hand, it showed low enrichment values for (Ni) & (Pb). In addition, the concentration of heavy metals in the roots of the plant was differentiated.

An environmentally friendly strategy for reducing the environmental risks of heavy metals adsorbed by kaolinite

Plenty of heavy metals (HMs) that are adsorbed on clay minerals (such as kaolinite), in addition to low molecular-weight organic acids (such as oxalic acid (OA)) with high activities, are widespread in the natural environment. In the present study, the effects of OA on the environmental behaviors of Pb2+/Cd2+ adsorbed by kaolinite have been investigated. The effectiveness and mechanisms of calcium silicate (CS) and magnesium silicate (MS) in reducing the environmental risks of the HMs have also been studied. The results showed that the releases of Pb2+/Cd2+ increased with an increasing concentration of OA. When different dosages of CS/MS were added to the aging system, a redistribution of HMs took place and the free form of Pb2+/Cd2+ decreased to very low levels. Also, the unextractable Pb2+/Cd2+ increased to high levels. Furthermore, a series of characterizations showed that the released HMs were re-captured by the CS/MS. In addition, the CS immobilized the OA in the solution during the aging process, which also facilitated an immobilization of the carbon element in the environment. In general, the present study has contributed to a further understanding of the transport behaviors of the HMs in natural environments, and of the interactions between CS (or MS), the environmental media, and the heavy metal contaminants. In addition, this study has also provided an eco-friendly strategy for an effective remediation of heavy metal pollution.

Оценка возможности использования отходов железо-магниевого производства для очистки сточных вод от тяжелых металлов (Cd2+, Zn2+, Co2+, Cu2+)

Relevant problems associated with treatment of industrial wastewater from heavy metal ions are considered. Due to industrial development, the amount of wastewater increases as well as the risks of heavy metals getting into surface and groundwater, accumulating in water bodies and becoming aggressive environmental pollutants, which affect the animal and human organisms. To assess the possibility of extracting metal ions (Cd2+, Zn2+, Co2+, Cu2+) from industrial wastewater and their further treatment, studies were carried out on redistribution of heavy metals in the “wastewater – waste” system using iron-magnesium production waste. Samples of the investigated waste weighing 0.1; 0.2; 0.5; 1; 1.5; 2 g were taken for wastewater volume of 50 ml per each subsample. Contact time varied from 5 to 180 min, waste fraction was 1 mm. The interaction process showed that the waste efficiently removes metal ions (Cd2+, Zn2+, Co2+, Cu2+) from industrial wastewater. The efficiency of removing a pollutant from the solution depends on the weight of the waste subsample, initial concentration of metal ions, and contact time.

Influences of energetic typhoons on the redistributions of heavy metals in sediments along the Leizhou Peninsula coast, southern China

The southern China coast areas are often invaded by typhoons, probably causing the redistribution of heavy metals in sediments. The knowledge of the influence of typhoons on the redistribution of heavy metals along the coasts is limited. The sea-floor sediments from the Leizhou Peninsula (LP) coast, southern China, were sampled to test the spatial distribution of the heavy metal before and after typhoons Barijat and Mangkhut in 2018. Results indicated that the coast suffered from varying levels of As contamination, while only minor enrichments were found in a few locations for other heavy metals. The pollution level on the western LP coast seemed to be higher than on the eastern coast. All heavy metals were mainly provided by terrigenous materials from the natural processes and were less affected by grain sizes. After the typhoon landings, more oxidation conditions promoted the deposits of As and the adsorption of Mo by MnO2.

Study on the mechanism of lead release from ash under the action of high-temperature flue gas

The interaction between flue gas and ash causes the redistribution of heavy metals and affect their emission characteristics. In this study, a double-layer fixed-bed reactor was used to investigate the effect of this interaction on Pb distribution at 800–1000 °C. Obvious gaseous Pb adsorption by ash just occurred in the case of high-Pb flue gas and less ash melting. In other cases, significant Pb release from ash occurred under the action of the high-temperature flue gas. The occurrences of Pb in ash was found to be thermally stable. Ash melting is the main reason for the Pb release. Gaseous Na in the combustion flue gas and reducing components in the pyrolysis flue gas promote the Pb release via promoting the ash melting. H2S and HCl in the pyrolysis flue gas also promote the Pb release by forming PbS and PbCl2, which are more volatile.

Impacts of water-sediment regulation on spatial-temporal variations of heavy metals in riparian sediments along the middle and lower reaches of the Yellow River

The water-sediment regulation scheme (WSRS) of dams influences the desorption, resuspension, and deposition processes of riparian sediments, which in turn affect the spatial-temporal variations of heavy metals (HMs) in riparian sediments and leads to severe degradation of soil and water quality. However, the difference between the trapping effect of dams and the redistribution effects of the WSRS on HMs in riparian sediments, as well as the consecutively seasonal change of HMs after the WSRS, are rarely reported. To fill this gap, the concentrations of six HMs including Cd, Cr, Cu, Ni, Pb, and Zn in riparian sediments along the Xiaolangdi Dam (XLD) Reservoir and its downstream reach were investigated, and the contamination level and potential ecological risk of HMs were assessed, to differentiate the effects of the XLD and its WSRS on the concentration, contamination level, and potential ecological risks of HMs. The results indicated that the mean HM concentrations in riparian sediments were higher than the background values in the study area and showed significant spatial and temporal variations. However, the regional differences of HM concentrations caused by the trapping effect of the XLD were less than the seasonal differences caused by the redistribution effects of the WSRS. The contamination and ecological risk assessment indicated that riparian sediments in the study area were contaminated by the six HMs, particularly by Cd and Pb, which overall exhibited a high and moderate ecological risk, respectively. The sources for Pb were likely agricultural inputs, while the sources for Cd should be attributed to both industrial and agricultural inputs. Overall, the trapping effect of the XLD led to the accumulation of HMs in riparian sediments along the reservoir area, while the regulation effects of the WSRS resulted in the redistribution of HMs in riparian sediments from the reservoir area to the downstream reach.

Landscape geochemical conditions and patterns of inter-element redistribution of heavy metals in landscapes of Kivertsi National Nature Park “Tsumanska Pushcha”


 
 
 nalysis of landscape geochemical conditions of the territory of Kivertsi National Nature Park “Tsumanska Pushcha” was carried out also the levels of pollution of landscapes within the park and adjacent territories were established. Features of the accumulation and distribution of pollutants in the landscapes of the territory under conditions of natural and Technogenic geochemical anomalies are considered. The landscapes of the studied migration classes (calcium, calcium carbonate, carbonate clayey, acidic calcium) are characterized by a relatively high coefficient of migration intensity due to relatively weak buffering capacity, low water retention capacity and contrasting moisture regime. However, strong gleyed horizons are able to fix contaminants during their surface movement. Using the methods of landscape geochemical research, analytical methods, data on the gross and mobile content of heavy metals were obtained and analyzed. The highest concentrations of manganese and chromium are found in soils differentiated on loess sediments, nickel and copper on glacial sediments. Most of the studied heavy metals exceed the regional geochemical background. In terms of the gross content in soils, trace elements form the following geochemical series: Zn>Cu>Pb>Ni>Mn>Cr. The accumulation of lead up to 2-3 MPC in forest litters is clearly traced. Dependences of the stability of landscapes to Technogenic pollution on the level of conservation of natural geochemical parameters of soils, the degree of their anthropogenic transformation and the level of heavy metals incomings have been established. All studied plants maximally accumulated Mn, Cu, Cr and minimally Zn and Ti which is consistent with the patterns of migration of these elements in the soil. The high accumulation of heavy metals in the aboveground part of the studied plants indicates a significant removal of elements from the soil, which, in turn, makes it possible to consider certain plant species as potential phytoremediators. According to the average values of the concentration of macro elements in plants, the following geochemical series is established: CaO>K2O>MgO>P2O5>SiO2>SO3> Al2O3> Fe2O3>Na2O>TiO2. On the basis of the data obtained, 4 types of biogeochemical bonds between chemical elements in the soil – plant system for the territory of the NPP were identified: V, Ti - soil> plant; Ni - soil <plant; Cr - soil> plant; Mn, Cu - soil <plant.
 
 

Distribution of heavy metals in plant communities of the West Siberian Arctic and Subarctic

The paper presents the results of comprehensive studies on the problem of formation of a deposit of heavy metals in plant communities of the West Siberian Arctic and Subarctic. The regularities of the concentration and redistribution of heavy metals in the soil-plant system have been revealed. Excessive accumulation of heavy metals by different plant species is limited by the selectivity of root absorption in relation to certain elements, and therefore it is important to calculate the coefficient of biological absorption. The interrelation between the intensity of recreational loading and change in the nature, grass cover structure.Among the identified pollutants that accumulate by plants identified a group of heavy metals and microelements (Pb, Sr, Cu, Zn, Ni ). It is shown that the linear dependence of the accumulation of metals in the system “soil-plant” is observed only in the range of low concentrations of pollutants in the ground growing. With high concentrations the reverse dependence occurs. Formulated, justified and tested methodical approaches to preparation of complex long-time observations of the natural ecosystems.

Heavy metals stress, mechanism and remediation techniques in rice (Oryza sativa L.): A review

The rapid pace of urbanization and industrialization makes soil and environment polluted, which may cause a severe issue of food chain contamination. Discharge of heavy metal(oid)s from industrial and municipal wastewater streams, and groundwater contamination causes a reduction in crop yields, degradation of soils and ruin quality. Cultivated Asian rice and heavy metal(oid)s have two ways of interaction, either heavy metal(oid)s accumulation cause harmful effects on rice crop or rice plants possess their resistance mechanism to protect against the toxic effects of heavy metal(oid)s, their uptake, and translocation also detoxify the heavy metal(oids) contamination. Besides, several inorganic (liming and silicon) and organic (compost and biochar) amendments have been applied in the soils to reduce/immobilize heavy metal(oid)s stress in rice. Selection/development of rice varieties resistant to heavy metals stress and bioaccumulation, crop rotation, water management and exogenous application of microbes could be a reasonable approach to alleviate heavy metal(oid)s toxicity in rice. This article review that heavy metals, such as aluminum, arsenic, cadmium, chromium, copper, mercury, and lead are the major environmental pollutants, mainly in the places having more significant anthropogenic pressure. In agricultural areas, accumulation of heavy metals is of primary concern because of their adverse effects. This review article also briefly discusses the impact of the heavy metals on human health, soil, plants, and their metabolic mechanisms induced by the biological and geological redistribution of heavy metals by soil and water pollution. Keywords: Accumulation; Dynamics; Heavy Metal(oids); Rice; Soil; Uptake http://dx.doi.org/10.19045/bspab.2020.90045

The impact of land use changes and erosion process on heavy metal distribution in the hilly area of the Loess Plateau, China

Land use change alters the hydrological process, which in turn affects the migration of heavy metals. However, analyses of the watershed-scale distribution of heavy metals from slope to dam fields have seldom been studied. In this study, three land-use types on the slope (cropland, shrubland, grassland) and dam land in the channel on the Loess Plateau were selected to analyze the relationship between the change of slope erosion rate and the migration process of Manganese (Mn), Chromium (Cr), Zinc (Zn), Vanadium (V), Nickel (Ni), Copper (Cu), Arsenic (As) and Cobalt (Co) in soil. Moreover, the sources of heavy metals in sediments and their historical deposition process were revealed. It was found that the concentrations of Cr and As were higher in cropland than that in grassland and shrubland. The soil erosion of cropland was the most serious, and the maximum annual erosion rate was as high as 10,853.56 t km−2. The distribution of heavy metals was related to erosion rate in the cropland. With soil erosion, Cr, V, As, Co and Zn in cropland were prone to runoff migration. Cr and As in dam sediments mainly originated from the agricultural activities in cropland. Cu, Co, Mn, Ni, V and Zn in the dam land were largely affected by soil parent material. Land use and soil erosion were important factors influencing the redistribution of heavy metals. By optimizing land use patterns and reducing soil erosion, it is possible to control the migration and accumulation of heavy metals in the watershed. The findings of this study can serve as important reference for reducing non-point source pollution.

Elucidating the differentiation of soil heavy metals under different land uses with geographically weighted regression and self-organizing map

Intensive anthropogenic activity has triggered serious heavy metal contamination of soil. Land use and land cover (LULC) changes bear significant impacts, either directly or indirectly, on the distribution of heavy metal in soils. A total of 180 samples were acquired from various land covers at different depths, namely surface soils (020 cm) and subsurface soils (20–40 cm). Spatial interpolation, geographically weighted regression (GWR) and self-organizing map (SOM) were used to discern how variations in the spatial distributions of soil heavy metals were caused by human activities for different land uses, and how these pollutants contributed to environmental risks. The medium concentrations of Cd, Cr, Cu, Pb and Zn in surface soil all exceeded the corresponding local background values in flat cropland and developed area soil. The overall ecological risk level of the study varied from low to medium. The GWR model indicated that the land use intensity had a certain influence on the accumulation of heavy metals in the surface soil. K-means clustering of the SOM revealed that the type of LULC also contributed to the redistribution of heavy metals in the surface soil.

Degree of partitioning of heavy metals in different environmental segments of a sewage-fed fishery pond at East Kolkata Wetland, India – A case study.

Anthropogenic activities like industrialization, unplanned urbanization, deforestation and profit oriented capitalism have resulted introduction of many undesirable substances into our immediate environment creating environmental degradation to a great extent. Normally, nature takes the responsibility of reducing the adverse effect of these substances through the operation of many physical, chemical and biological processes such that these substances can be partitioned in various biotic and a-biotic components of an environmental ecosystem. Present study is an attempt to highlight the extent of partitioning of some heavy metals in the compartments of water, sediments, macrophyte and fishes of a sewage-fed fishery pond in East Kolkata Wetland (EKW). Study distinctly revealed that all heavy metals show a common preference to be deposited on the sediments with higher values (28.5 to 56.5%) followed by macrophytes (20.3 to 35.4%), fishes (15.7 to 43.2%) and water (less than 1.0%). Similar types of partitioning might be observed in each higher plants and animals. As an example, in fishes, higher accumulation of heavy metals were in viscera (27.5 to 69.2%) followed by bone (4.6 to 47.7%), gill (8.1 to 30.6%) and least in flesh (< 1.0 to 19.0%). Again, in cases of toxic metals, it has been observed that flesh contains less than 1% and while the essential group of metals (Zn and Cr) showed comparatively higher degree of accumulation (11.3 to 19.5 %). Thus, the study evidently forecasted that re-distribution of heavy metals in large number of inter and intra compartments of natural biotic and abiotic agents, could be considered as the most effective mechanism for reducing the undesirable consequences of heavy metals or any toxic waste along with passage of time.

Accumulation of heavy metals by family Lymnaeidae representatives as response to anthropogenic pollution critical levels of South Ural reservoirs

The features of heavy metals accumulation by Lymnaea fragilis and L. psilia were researched for the aerate emission polluted area of Karabash copper-smelting manufacturing (Southern Ural). These features are concluded with selective redistribution of heavy metals between soft tissues and the shell of Lymnaea. The heavy metals accumulation takes place by three independent tendencies: water soft tissues, water shell and soft tissues shell. The heavy metals content levels a thousand times exceed the physiological norm in soft tissues while in shell they exceed manifold. In the first place manganese and iron are accumulated while the cobalt, cadmium and molybdenum are finalizing the researched rank of accumulation. It has been ascertained that more biophil manganese are accumulated in mollusk soft tissues more than in other metals, while slightly less biophil iron is accumulated in shell, mainly in surface layers. For soft tissues and shell different ranks of heavy metals accumulation are observed, but these ranks are similar for different habitats, thus qualitative biogeochemical similarity is observed. The heavy metals accumulation in the system water soft tissues shell can help to estimate the extent of the metal environment pollution as well as local biophility of this metal. The adaptive response of pond snails to anthropogenic pollution is that there are more of them in less polluted reservoirs and less in more polluted reservoirs. It has been confirmed, that high heavy metals concentration and low pH level in reservoirs leads to death and absolute absence of these mollusk species.

Heavy metal redistribution mechanism assisted magnetic separation for highly-efficient removal of lead and cadmium from human blood

Magnetic nano capture agent (MNCA)-based magnetic separation is considered as a promising approach to rapidly isolate heavy metals from blood. Limited removal efficiency and potential biosafety risks are the major challenges for the clinical use of MNCA-based magnetic separation. Here, we report a highly-efficient MNCA-based magnetic separation of heavy metals from blood in continuous multi-stage adsorption mode. The interactions between MNCA and blood components (e.g. blood cells and plasma proteins) and the MNCA-induced cellular immune responses are studied in detail. The distribution and redistribution of heavy metals in blood are quantitatively analyzed. It demonstrates that concentration dependent redistribution can increase the contact between heavy metals and MNCA, leading to improvement on heavy metal removal efficiency. The removal performance is tested in batch mode and in continuous mode. Results show that 97.97% of Pb and 96.53% of Cd are removed from blood in 120 min using continuous multi-stage adsorption mode, and the residual concentrations of Pb and Cd in blood decrease from 400 μg L−1 to 8.11 μg L−1 and 13.84 μg L−1, respectively. This study paves an effective way for heavy metal intoxication therapy by MNCA-based magnetic separation.

The accumulation and redistribution of heavy metals in the water-level fluctuation zone of the Nuozhadu Reservoir, Upper Mekong

The accumulation and redistribution of heavy metals in soil in a water-level fluctuation zone (WLFZ) can create ecological risks to reservoirs and reduce river health. Little is known about how heavy metals are accumulated and redistributed in the WLFZ of reservoirs with a high background value of the heavy metal in soil. The site chosen for this case study is the Nuozhadu mega reservoir in the upper Mekong River Basin, which is held back by a dam with a height exceeding 250 m. Five sampling transects were established around the reservoir. Each transect contained three vertical sampling lines representing three land-use types: forest, farmland, and rubber plantations. Soil samples were collected both in the WLFZ and in the infralittoral reference zone (IRZ), and the concentrations of the heavy metals Zn, Cr, Ni, Cu, Mn, and Fe (%) were measured in these samples. We found that the average concentrations of each of these heavy metals were higher in the WLFZ than in the IRZ. The land-use types, especially the rubber plantations and farmlands, determine the redistribution of the heavy metals in the soil of the WLFZ. The heavy metals Cu, Mn, and Ni increased with increasing elevation within the WLFZ, but the metals Cr and Zn decreased with elevation. The results of analysis of variance indicate that the soil properties had certain differences under different land-use types and inundation durations at various elevations, which partly determined the accumulation and redistribution of heavy metals in the WLFZ. We suggest that long-term monitoring of the concentration of heavy metals is needed for soil and water management in the WLFZ of the Nuozhadu reservoir.

Effect of bamboo and rice straw biochars on the mobility and redistribution of heavy metals (Cd, Cu, Pb and Zn) in contaminated soil

Biochar has emerged as an efficient tool to affect bioavailability of heavy metals in contaminated soils. Although partially understood, a carefully designed incubation experiment was performed to examine the effect of biochar on mobility and redistribution of Cd, Cu, Pb and Zn in a sandy loam soil collected from the surroundings of a copper smelter. Bamboo and rice straw biochars with different mesh sizes (<0.25 mm and <1 mm), were applied at three rates (0, 1, and 5% w/w). Heavy metal concentrations in pore water were determined after extraction with 0.01 M CaCl2. Phytoavailable metals were extracted using DTPA/TEA (pH 7.3). The European Union Bureau of Reference (EUBCR) sequential extraction procedure was adopted to determine metal partitioning and redistribution of heavy metals. Results showed that CaCl2-and DTPA-extractable Cd, Cu, Pb and Zn concentrations were significantly (p < 0.05) lower in the bamboo and rice straw biochar treated soils, especially at 5% application rate, than those in the unamended soil. Soil pH values were significantly correlated with CaCl2-extractable metal concentrations (p < 0.01). The EUBCR sequential extraction procedure revealed that the acid extractable fractions of Cd, Cu, Pb and Zn decreased significantly (p < 0.05) with biochar addition. Rice straw biochar was more effective than bamboo biochar in decreasing the acid extractable metal fractions, and the effect was more pronounced with increasing biochar application rate. The effect of biochar particle size on extractable metal concentrations was not consistent. The 5% rice straw biochar treatment reduced the DTPA-extractable metal concentrations in the order of Cd < Cu < Pb < Zn, and reduced the acid extractable pool of Cd, Cu, Pb and Zn by 11, 17, 34 and 6%, respectively, compared to the control. In the same 5% rice straw biochar treatments, the organic bound fraction increased by 37, 58, 68 and 18% for Cd, Cu, Pb and Zn, respectively, compared to the control, indicating that the immobilized metals were mainly bound in the soil organic matter fraction. The results demonstrated that the rice straw biochar can effectively immobilize heavy metals, thereby reducing their mobility and bioavailability in contaminated soils.

Distribution and risk assessment of heavy metals in sewage sludge after ozonation.

In this paper, transformation of chemical forms of heavy metals (Cu, Zn, Ni, Pb, Cr, Cd, Mn, and Mg) in sewage sludge (SS) during ozonation was investigated. Meanwhile, the risk of heavy metals to environment in ozonated sludge (OS) and SS was estimated according to risk assessment code (RAC). The residual rates of heavy metals were over 72.8%, which demonstrated that the heavy metals in SS were mainly existed in the OS after ozonation. The results indicated that the ozonation had an effect on the redistribution of heavy metals. The comparisons of the RAC between OS and SS indicated that the environmental risk of heavy metals in OS was aggravated compared to SS, except for Mg. Consequently, it was suggested that the OS should be pretreated before application.

Speciation evolutions of target metals (Cd, Pb) influenced by chlorine and sulfur during sewage sludge incineration

In sludge incineration, the thermal behavior of heavy metal is a growing concern. In this work, the combined analysis of metal partitioning behavior between vapor phase and condensed phase, speciation redistribution in condensed phase and the difference of metal species in binding energy was carried out to investigate the possible volatilization-condensation mechanism of heavy metals in high-temperature sludge incineration. It was found that there were two steps in metal volatilization. The initial volatilization of heavy metal originated from their exchangeable (EXC), carbonate bound (CAR) and iron-manganese bound (FM) fractions, which is primarily composed of simple substance, chlorides, oxides and sulfides. With the increase of chlorine and sulfur in sludge, the inner speciation redistribution of heavy metals occurred in condensed phase, which was an important factor affecting the potential volatility of heavy metals. A partial of metal species with complexed (COM) and residual (RES) fractions gradually decomposed into simple substance or ions, oxides and carbonates, which significantly strengthened the second volatility. In presence of chlorine, about 46% of Cd with the RES fraction disappeared when the volatility rate of Cd increased by 44.89%. Moreover, about 9% of Pb with COM fraction disappeared when there was an increase of nearly 10% in the volatilization rate. Thus, the second volatilization was mainly controlled by the decomposition of metal species with COM and RES fractions. By virtue of XRD analysis and the binding energy calculation, it was found that metal complex and silicates were inclined to decompose under high temperature due to poor thermo stability as compared with sulfates.

Anthropogenic Influences on Cd, Cr,Cu, Ni, Pb and Zn Concentrations in Soils and Sediments in a Watershed with Sugar Cane Crops at São Paulo State, Brazil

The use of fertilizers NPK and amendments in sugar cane crops may change the heavy metalsconcentrations in soils, making them available for plants and, consequently, they can be transferred to thehuman food chain. This study describes the redistribution of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in soils with sugar cane crops due to fertilizers NPK and amendments at Corumbatai River basin, Sao Paulo State. The heavy metals concentrations were determined in samples of fertilizers NPK (5:25:25) and amendments (limestones, KCl, and phosphogypsum) by atomic absorption spectrometry (AAS). Heavy metals incorporated in fertilizers NPK and amendments are annually added in the sugar cane crops, but if utilized in accordance with the recommended rates, they do not raise the concentration levels in soils up to hazards values. Those applications promote the decrease of heavy metals concentration in soils profiles with sugar cane crops due to their fractionation to water soluble and/or exchangeable fractions, and the results still indicate that the profiles do not possess hazard levels in relation to heavy metals concentration. In relation to metals concentration in a sediment core, Cu, Ni, Pb and Zn values increased progressively from 1974 to 2000 due to anthropogenic activities, mainly sugar cane crops, indicating adverse biological effects to the aquatic environment and to organisms living in or having direct contact with sediments.