Significant Amounts Of Heavy Metals Research Articles

Risk Assessment of Toxic Heavy Metal Exposure through Medicinal Herbs in the Indian State of West Bengal

Background: More than 80% of the world's population uses herbal remedies in some form. Heavy metal contamination and the attendant health risks of Indian herbal medicines are not adequately documented. Objective: This study aimed to investigate the health risks associated with four common heavy metal contaminants, namely lead, arsenic, cadmium, and mercury, present in raw medicinal herbs cultivated or growing wild in the West Bengal state of India. Method: A total of 197 raw herbs obtained from herbal medicine practitioners or wild plant col-lectors from 16 districts spread across 3 geographical zones (south, central, north) of West Bengal were analyzed. In accordance with AOAC specifications, all samples were dried in a hot air oven, ground into a coarse powder, and then processed and analyzed for heavy metals through atomic absorption spectrometry. The mean concentrations were estimated along with standard devia-tions, overall, zone-wise, and according to the botanical part tested. The standardized human health risk indices were calculated from the results. Results: Significant amounts of heavy metals were found in the herb samples analyzed in the order: lead in 150 samples (76.1%), arsenic in 84 (42.6%), cadmium in 77 (39%), and mercury in 47 (23.8%). Central zone samples had the highest concentrations of lead (10.06 μg/g), arsenic (0.62 μg/g), and cadmium (0.54 μg/g), while the greatest amount of mercury (0.08 μg/g) was obtained in herbs from South zone. There were also considerable variations with respect to the source of the botanical part. Lead and cadmium concentrations showed a significant positive cor-relation (r = 0.588). Although risk assessment using standardized measures indicated some risk, the human Hazard Index (HI) was less than 1 for all metals, indicating that it was mostly safe to use the herbs in the short-term. However, the risk of health issues from prolonged use still re-mains. Conclusion: Significant contaminations were identified, but exposure would mostly be within acceptable risk levels at present. However, since risk would be cumulative over time, programs need to be in place to monitor pharmaceutical herb safety, identify local sources of pollution, and take appropriate remedial action.

Quantifying Heavy Metal Accumulation in Soil and Vegetation Surrounding Industrial Areas: A Comprehensive Environmental Toxicology Study

Background: Industrial activities release significant amounts of heavy metals into the environment, contaminating soil and vegetation. This pollution poses severe risks to ecosystems and human health, making it a crucial area of study. Objective: To quantify the accumulation of heavy metals in soil and vegetation surrounding industrial areas and assess the ecological risks associated with this contamination. Methods: The study involved quantitative analysis of soil and plant samples from industrial and control areas. Heavy metals analyzed included lead, cadmium, mercury, arsenic, chromium, and nickel. Methods included atomic absorption spectroscopy for metal quantification, bioaccumulation factor (BAF) calculation for plants, and ecological risk assessment using the ecological risk index (ERI). Results: Soil samples from industrial zones showed significantly higher concentrations of lead (175 mg/kg), cadmium (8 mg/kg), and chromium (90 mg/kg) compared to control areas (lead: 30 mg/kg, cadmium: 2 mg/kg, chromium: 20 mg/kg). Plant tissues from these areas also revealed elevated levels of lead (12 mg/kg), cadmium (2 mg/kg), and nickel (8 mg/kg), against lower concentrations in control samples (lead: 3 mg/kg, cadmium: 0.5 mg/kg, nickel: 2 mg/kg). The ecological risk index underscored a high risk in industrial zones (ERI = 85) compared to control areas (ERI = 30). Conclusion: The study highlights the critical contamination of soil and vegetation with heavy metals near industrial zones and the consequent ecological risks. These findings emphasize the need for immediate remediation strategies and stricter regulatory frameworks to mitigate the impacts of this pollution.

Global Chemical Characterization of Sargassum spp. Seaweeds from Different Locations on Caribbean Islands: A Screening of Organic Compounds and Heavy Metals Contents

Large-scale strandings of Sargassum spp. seaweeds occur annually on the beaches of the Caribbean islands and cause major environmental, health, and economic problems. In order to support an approach of valorisation of algae, an exhaustive characterisation of the composition of these seaweeds has been performed by analysing the contents in alginates, structural carbohydrates (fucans and glucans), minerals, proteins, lipids, mannitol, polyphenols, and heavy metals. Nine batches were collected at different harvesting sites over the years 2021 and 2022, to estimate the spatial and temporal variation in Sargassum composition. A batch of floats was harvested and analysed to estimate the differences in composition between floats and whole algae. Samples collected during the same year (floats or entire plant, freshly collected or stored) showed no significant differences in composition. However, slight differences were observed between batches collected in the two years. Some samples showed significant amounts of heavy metals, especially arsenic. A detailed structural carbohydrates analysis was carried out and discussed with literature data. As the nitrogen content of algae is an interesting parameter for food or agronomic uses, protein analysis enabled us to calculate a new nitrogen–protein conversion factor, specific to these algae species.

Environmental Cadmium Exposure Perturbs Gut Microbial Dysbiosis in Ducks.

Ore extraction, chemical production, and agricultural fertilizers may release significant amounts of heavy metals, which may eventually accumulate widely in the environment and organisms over time, causing global ecological and health problems. As a recognized environmental contaminant, cadmium has been demonstrated to cause osteoporosis and renal injury, but research regarding the effects of cadmium on gut microbiota in ducks remains scarce. Herein, we aimed to characterize the adverse effects of cadmium on gut microbiota in ducks. Results indicated that cadmium exposure dramatically decreased gut microbial alpha diversity and caused significant changes in the main component of gut microbiota. Moreover, we also observed significant changes in the gut microbial composition in ducks exposed to cadmium. A microbial taxonomic investigation showed that Firmicutes, Bacteroidota, and Proteobacteria were the most preponderant phyla in ducks regardless of treatment, but the compositions and abundances of dominant genera were different. Meanwhile, a Metastats analysis indicated that cadmium exposure also caused a distinct increase in the levels of 1 phylum and 22 genera, as well as a significant reduction in the levels of 1 phylum and 36 genera. In summary, this investigation demonstrated that cadmium exposure could disturb gut microbial homeostasis by decreasing microbial diversity and altering microbial composition. Additionally, under the background of the rising environmental pollution caused by heavy metals, this investigation provides a crucial message for the assessment of environmental risks associated with cadmium exposure.

Synthesis and environmental application of TTCHEA resin in effluent handling

Industrial effluents include significant amounts of heavy metals. The elimination of these ions causes great concern towards the environment. The flora and fauna of the aquatic and terrestrial environments are significantly impacted by rising levels of these metal pollutants in the environment. In order to develop new chelating resin, tamarind kernel powder was employed. TKP derivative of tertiary amine acts as metal ion exchanger cum a janitor for removal of harmful toxic metal ions from effluents of mineral and metallurgical industries. This study describes adsorption process for removal of toxic metal ions from wastewater. In dioxane medium, serine was bound to TKP backbone. The resulting ion exchange resin has been used for treatment of effluents. Interesting data were obtained showing the way in which various metal pollutants were removed throughout the depth of resin bed. FTIR methods have been used to describe the structure of the chelating resin.

Adverse environmental effects of disposable face masks due to the excess usage

The widespread use of disposable face masks as a preventative strategy to address transmission of the SARS-CoV-2 virus has been a key environmental concern since the pandemic began. This has led to an unprecedented new form of contamination from improperly disposed masks, which liberates significant amounts of heavy metals and toxic chemicals in addition to volatile organic compounds (VOCs). Therefore, this study monitored the liberation of heavy metals, VOCs, and microfibers from submerged disposable face masks at different pH (4, 7 and 12), to simulate distinct environmental conditions. Lead (3.238% ppb), cadmium (0.672 ppb) and chromium (0.786 ppb) were found in the analyzed leachates. By pyrolysis, 2,4-dimethylhept-1-ene and 4-methylheptane were identified as the VOCs produced by the samples. The chemically degraded morphology in the FESEM images provided further evidence that toxic heavy metals and volatile organic compounds had been leached from the submerged face masks, with greater degradation observed in samples submerged at pH 7 and higher. The results are seen to communicate the comparable danger of passively degrading disposable face masks and the release of micro- or nanofibers into the marine environment. The toxicity of certain heavy metals and chemicals released from discarded face masks warrants better, more robust manufacturing protocols and increased public awareness for responsible disposal to reduce the adverse impact on ecology and human health.

Physicochemical assessment and treatment of produced water: A case study in Niger delta Nigeria

The most important waste stream created during oil and gas production is oilfield-produced water. When discharged without treatment, it poses a significant risk of pollution of marine ecosystems. While adequate treatment before disposal is acceptable, achieving authorized discharge criteria continues to be a problem for the petroleum sector. This research examined the physicochemical characteristics of produced water at various month intervals before and after treatment. Heavy metal and organic component concentrations in water samples were determined using atomic absorption spectroscopy and gas chromatography. The results indicate that produced water from a certain Niger Delta oilfield contains significant amounts of heavy metals and some organic compounds after treatment. The present laws, as well as the measurement of dispersed oil and grease content, have been in place for a long period of time without considerable change, even though most dangerous components in produced water are dissolved. It is recommendable for the prospective field developers/operators to consider the dissolved components of produced water and consider the economic consequences of adopting tertiary produced water polishing technologies.

Heavy metal accumulation by roadside vegetation and implications for pollution control.

Vehicular emissions cause heavy metal pollution and exert negative impacts on environment and roadside vegetation. Wild plants growing along roadsides are capable of absorbing considerable amounts of heavy metals; thus, could be helpful in reducing heavy metal pollution. Therefore, current study inferred heavy metal absorbance capacity of some wild plant species growing along roadside. Four different wild plant species, i.e., Acacia nilotica L., Calotropis procera L., Ricinus communis L., and Ziziphus mauritiana L. were selected for the study. Leaf samples of these species were collected from four different sites, i.e., Control, New Lahore, Nawababad and Fatehabad. Leaf samples were analyzed to determine Pb2+, Zn2+, Ni2+, Mn2+ and Fe3+ accumulation. The A. nilotica, Z. mauritiana and C. procera accumulated significant amount of Pb at New Lahore site. Similarly, R. communis and A. nilotica accumulated higher amounts of Mn, Zn and Fe at Nawababad and New Lahore sites compared to the rest of the species. Nonetheless, Z. mauritiana accumulated higher amounts of Ni at all sites compared with the other species included in the study. Soil surface contributed towards the uptake of heavy metals in leaves; therefore, wild plant species should be grown near the roadsides to control heavy metals pollution. Results revealed that wild plants growing along roadsides accumulate significant amounts of heavy metals. Therefore, these species could be used to halt the vehicular pollution along roadsides and other polluted areas.

Removal of humic substances from surface waters with recycled fluidized bed sand

ABSTRACT Recycled bed sand from a power plant’s fluidized bed reactor was used to remove humic substances (HSs) from surface water samples. The performance of sand samples screened into different size fractions together with unscreened sand was evaluated in removing HSs by performing shaking and column experiments, and by monitoring the quality of the treated water samples in terms of pH, conductivity, chemical oxygen demand (COD), and colour. At the beginning of the column experiments, the used sand fractions removed HSs with over 80% efficiency. However, as the experiments proceeded, the removal efficiency rapidly decreased, reaching a steady state during which a column filled with small-particle-size screened sand removed 20–25% of the COD and colour at a 2.2 kg/h flow speed, and 25–35% of the COD and 30–35% of the colour at a slow 0.5 kg/h flow speed. With unscreened sand, the corresponding COD and colour removal efficiencies were 10–20% (COD) and 10–18% (colour) for fast column experiments, and 22–27% for COD and 25–30% for colour during slow column experiments. Elemental analysis revealed that recycled fluidized bed sand contained several cationic compounds known to form complexes with HSs. Especially calcium together with aluminium and iron are potential candidates for removing colour and COD from the water samples. Highlights Recycled fluidized bed sand could be used as a low-cost adsorbent material for removing HSs from surface water samples Especially the COD and colour of the water samples could be reduced by the sand treatments Fluidized bed sand contained several cationic compounds forming complexes with HSs No significant amounts of heavy metals were leached during the sand treatments

Оценка защитного потенциала почвенного покрова Московской области к загрязнению тяжёлыми металлами и металлоидами

Heavy metals and other trace elements that are not subject to degradation are among the priority pollutants. Significant amounts of heavy metals and related elements with variable valence are deposited on the soil surface as part of aerosols. Accumulating in the soil, they are very slowly removed from it, only changing the level of content or the state during migration, turning the soil over time into a source of secondary pollution. In this regard, an extremely urgent task is to assess the territory, especially such a highly developed and densely populated area as the Moscow Region, in terms of its protective potential to heavy metal pollution. The paper proposes and tested an algorithm for the cartographic assessment of the protective potential of the soil and vegetation cover of the region using GIS analysis methods based on the database “Digital medium-scale soil map of the Moscow region” and a vector map of forest cover. The formula used for calculations includes data on the soil texture, the content of organic matter in soil, the position of the soil in the landscape and the degree of forest cover of the territory. According to the proposed approach, in the Moscow region, the soil cover, taking into account the forest cover, forms 4 groups according to the level of protective potential for contamination with heavy metals and metalloids. The maximum estimate was obtained for noneroded sod-podzolic soils of medium or fine texture, gray forest soils, chernozems and peat bog soils under forest vegetation (17 % of the area). Unerroded soddy-podzolic soils of varying degrees of podzolization and gleying (45 %) received an average rating. Even lower is the protective potential of 22 % of the territory represented by eroded gray forest soils, various sod-podzolic, alluvial and peat bog soils. This group is the most heterogeneous in terms of soil texture, organic matter content and degree of forest cover. The group with a minimum protective potential included eroded soils, soils of gully-girder complexes, sod-podzolic soils of coarst texture, as well as alluvial peat and peaty soils (about 16 %).

СОДЕРЖАНИЕ КОБАЛЬТА И КАДМИЯ В ТКАНЯХ РАСТЕНИЙ ТЕХНОГЕННОЙ ЗОНЫ

The collection of heavy metals in soils is a threat to public health and agriculture. Wild and cultivated plants are able to accumulate significant amounts of heavy metals, which on the one hand allows the use of phytopreparations to correct microelement exchange and eliminate hypomicroelementosis. The work shows the results of study of the content of cobalt and cadmium in wastewater, soil and the aboveground part of medicinal and forage plants in the fields of wastewater irrigation located in the sanitary protection zone of Orenburg gas processing plant. 9 types of plants used in medical and veterinary practice in Russia were selected for the study. Water, soil, and plant samples were collected at the end of June from 2018 to 2020. The TM content was determined on the basis of the interdepartmental complex analytical laboratory of FSBEI HE «Orenburg state agrarian university» by atomic absorption spectroscopy using the «Spektr-5» atomic absorption spectrometer (Russia). The ability of species to accumulate cadmium and cobalt in the aboveground part (assimilating and generative organs) was determined. According to the results of the research, the ability of the studied plants to control to a certain extent the intake of cobalt and cadmium from the environment to generative and assimilating organs is seen. Specific differences in the nature of accumulation of cobalt and cadmium in the aboveground part of the studied plants were determined. The results of the study may be of interest for planning enterprises for phytoremediation of technogenically polluted soils and evaluating the quality of medicinal and feed plant raw materials.

Removal of nickel(II) from wastewater using a zeolite-packed anaerobic bioreactor: Bacterial diversity and community structure shifts

In recent years, overexploited industrialization and urbanization activities have led to significant amounts of heavy metals released into the environment. Metal ion contamination of water, especially with toxic metals such as nickel(II) [Ni(II)], which is extensively applied in the electroplating industry, has been a serious problem. The aim of the present study was to evaluate the Ni(II) removal from real industrial wastewater using a 2 L, lab-scale, up-flow, anaerobic, zeolite-packed bioreactor inoculated with a heterotrophic consortium as the bioadsorbent. High-throughput sequencing of 16S rRNA genes revealed significant shifts in their bacterial diversity and structural composition along the bioreactor treatment location, where the bacterial genus was dominated by Kosmotogae followed by Firmicutes as Ruminococcus and Clostridium. However, Fervidobacterium and the Geobacter genus were absent at the end of the bioreactor treatment, suggesting that they play a key role in the beginning of Ni(II) removal anaerobic treatment. The physico-chemical results revealed that the Ni(II) removal rate was 99% for 250–500 ppm metal tested, with an efficient alkalinity rate and high production of biogas, which confirmed that anaerobic digestion of microorganisms was successfully performed through the process. Finally, this anaerobic bioreactor configuration offers an accessible and ecofriendly high-rate metal removal strategy from mining and electroplating effluents.

Assessment of heavy metals content and consumer health risk to Siganus fuscescens (Houttuyn, 1782) from Quang Binh province

Siganus fuscescens Houttuyn, 1782 is one of the common fish species in Quang Binh province and consumers are favored by its high nutritional value. However, the consumption of Siganus fuscescens may pose potential risks to human health since they can accumulate significant amounts of heavy metals in their tissues. From July to October 2019, a total of 50 individuals of Siganus fuscescens were randomly collected through fishermen at local markets in Quang Binh province. Liver, gills, and muscles were dissected and analyzed for cadmium, lead, copper, zinc, and iron contents by the flame atomic absorption spectrometer, and the cold vapor atomic absorption spectrometer for mercury content. The metal content in all tested samples was lower than the threshold limit value by the Vietnamese Ministry of Health (MoH). The risk to human health by the intake of metal contaminated Siganus fuscescens was evaluated by estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI). All the EDI values were below the provisional tolerable daily intake (PTDI) set by the MoH, and all of THQ and HI values for male and female consumers did not exceed 1, indicating that there was no potential human health risk in consuming Siganus fuscescens from coastal areas of Quang Binh province.

A Case Study On Predicting The Environmental Impacts Of Untreated Effluent Generated From Tannery Industrial Estate In Dhaka, Bangladesh

Significant amounts of heavy metals in the directly discharged wastewater released from the newly built tannery industrial site in Dhaka, Bangladesh are reported. Despite their detrimental impacts on public health and natural ecosystem, no environmental impact study is yet conducted. Therefore, information on safe discharge rates are not available. In this study, the extent of pollution around the industrial site is investigated for four representative trace metals. Temporal and spatial distributions of chromium (Cr), lead (Pb), cadmium (Cd) and arsenic (As) have been predicted using a numerical model with the aim to estimate safe discharge of these metal contaminants. From multiple simulation runs it has been estimated that a discharge of0.026 m3 of wastewater per day can lead to high levels of Cr and Pb accumulation, exceeding the regulatory standard limits, in the study area. Whilst As and Cd concentrations remain below the advised limits in most cases at this rate. However, an order of magnitude reduction in the total discharge rate, i.e.,0.0026 m3 per day, results into the metal accumulation below the recommended guidelines in all cases. Elevated concentration of Pb is found to be limited to the top 0.5 m of the soil as compared to Cr, As and Cd, which exhibit larger spread along the depth of the soil. The relative dominance of the metal contamination follows the sequence: Pb>Cr>As>Cd as sorbed concentration in soil aggregates and Cr>Pb>As>Cd as aqueous concentration in soil porewater. Further investigations that are essential for a comprehensive environmental impact assessment have been highlighted.

Characterization of Fungal Endophytes Isolated from the Metal Hyperaccumulator Plant Vachellia farnesiana Growing in Mine Tailings.

Heavy metal pollution has become an environmental and health problem worldwide. With the aim of finding novel strategies for metal bioremediation, endophytic fungi from the heavy metal hyperaccumulator plant Vachellia farnesiana were isolated and characterized. The plants were growing in mine tailings, rich in Zn, Pb, and Cu. Morphological and phylogenetic analyses indicated that the fungal strains belonged to Neocosmospora and Aspergillus genera. The Neocosmospora isolate belongs to the Fusarium solani species complex (FSSC) that groups phytopathogen species. However, in this case the plants from which it was isolated did not show any signs of disease. Both fungal strains were able to remove significant amounts of heavy metals from liquid cultures, either in a mixture of the three metals or each metal in a single culture. In response to lead exposure, the Neocosmospora sp. strain secreted specific novel phenolic compounds other than anthraquinones or naphtoquinones, which have been described in similar situations. The Aspergillus sp. dropped the pH in the medium. High-performance liquid chromatography determinations indicated that this strain secreted mainly glutamic acid in response to lead, a novel mechanism, which has not been reported elsewhere. Malic and succinic acids were also produced in response to lead exposure. Possibly, glutamic and succinic acids (synthesized in the Krebs cycle) can be used to cope with metal toxicity due to the plant providing photosynthates to the fungus. These fungi showed the potential to be used for bioremediation or restoration of metal-polluted environments.

Characterization of dusts from secondary copper production

Various types of waste, including dusts, are produced in the pyrometallurgical production of copper from secondary raw materials. According to the European Waste Catalogue and Hazardous Waste List, dusts from secondary copper production are classified as hazardous waste. In secondary copper production 3.87 million tons of copper were produced worldwide in 2017. The dusts are produced in the following thermal operations: reduction of the melt in the shaft furnace (shaft furnace dust), converting (converter dust), and pyrometallurgical refining (refining dust). These dusts contain significant amounts of heavy metals (Zn, Pb, and Sn) in oxidic forms. The dusts are regarded as secondary raw materials, and it is necessary to look for ways of extracting these heavy metals. The aim of this work was to characterize the individual types of dust and determine their quantitative and qualitative composition. The content of heavy metals in copper shaft furnace dust is (52.16% Zn, 19.33% Pb), in copper converter dust (32.40% Zn, 14.46% Pb), and in refining dust (32.99% Zn).

Highly efficient recovery and clean-up of four heavy metals from MSWI fly ash by integrating leaching, selective extraction and adsorption

Municipal solid waste incineration (MSWI) fly ash contains significant amounts of heavy metals (e.g., Cd, Cu, Pb and Zn) and is therefore considered to be a hazardous waste requiring proper treatment prior to its disposal. In this work, an integrated hydrometallurgical process for treatment of MSWI fly ash was evaluated. Valuable metals, e.g. Cu and Zn, were first recovered by combining leaching and extraction sequentially. In the next step, the t removal of Cd and Pb from the remaining leachate using four types of iron-based adsorbents was evaluated. The leaching was optimized with respect to pH, leaching time and liquid to solid ratio. A test done under optimal conditions gave metal releases of 100% and 80% for Cu and Zn as well as 100% and 85% for Cd and Pb, respectively. The resulting leachate was contacted with organic phases based on kerosene containing the extractants LIX860N–I for Cu extraction and Cyanex 572 for Zn extraction in two consecutive steps. Efficient extractions were achieved, thus demonstrating that the combination of leaching and extraction can be successfully used for the recovery of Cu and Zn. Adsorption of heavy metal ions on various iron based sorbents to detoxify the aqueous effluent from the extraction showed good removal efficiency (more than 95%) for both Cd and Pb. The results of this study show that the proposed integrated process is a promising tool that can be used in the strategy for metal recovery and detoxification of MSWI fly ash.

Comparative study of heavy metal residues in struvite products recovered from swine wastewater using fluidised bed and stirred reactors.

Struvite (MgNH4PO4·6H2O) crystallisation is a promising approach for phosphorus recovery from swine wastewater. Currently, intensive pig feeding has made heavy metals (HMs) extensive in swine wastewater; therefore, significant amounts of HMs have been detected in struvite recovery products. In this study, the HM residues in the struvite products recovered from stirred and fluidised bed reactors were investigated. The results showed that Zn, Mn, and Cu were the most abundant elements in swine wastewater (1,175.3 ± 178.0, 745.4 ± 51.5, and 209.3 ± 54.4 μg L-1, respectively). The HMs, especially Zn (97.0%) and Cu (96.8%), were mainly distributed in the total suspended solids (TSS) of the swine wastewater. Redundancy analysis revealed that the HMs in the struvite products harvested from the fluidised bed reactor were mainly attributable to the aggregation of dissolved matters, because most TSS were elutriated through fluidisation. In contrast, the HMs in the struvite products harvested from the stirred reactor mainly originated from the TSS, which complexed with the HMs, and co-precipitated and settled with the struvite products. Furthermore, chemical fractionation of the HM species confirmed that the presence of HMs in the struvite products was mainly attributable to metal precipitation and organic aggregation.

Effect of Pig and Cattle Slurry Application on Heavy Metal Composition of Maize Grown on Different Soils

Cattle and pig manure contain useful mineral nutrients (N, P, and K) and are therefore used as organic fertilizer. However, excessive applications of manure can cause environmental problems and threaten animal and human health because these materials also hold significant amounts of heavy metals, particularly Cu and Zn. To assess the potential risk due to the increased concentrations of heavy metals (Cu, Mn, Zn, and Cr) in a harvested crop, two maize hybrids were grown in pots on four different soils with three different fertilisers (urea, pig manure, and cattle manure). Both soil and manure characteristics influenced the heavy metal concentrations in the plant shoots. Organic fertilisation strongly interacted with the soils and, in general, reduced the shoot content of Cu, Mn, and Zn. A preliminary assessment of the heavy metal balance of the agricultural systems based on the intensive livestock production and maize cultivation showed that the potential soil enrichment of the long-term application of livestock manure arises mainly from the application of pig slurries that have a high content of Cu and Zn. The time required to apply an amount of metal that is equal to the initial soil content is 60–300 years for Zn and 240–450 years for Cu, depending on the soil type and the initial heavy metal content.

ENRICHMENT FACTORS OF HEAVY METALS IN IRON - MANGANESE CONCRETIONS FROM IMPERFECTLY DRAINED SOILS

The Fe-Mn concretions are morphological features of soils under alternating oxidizing and reducing conditions. They have a high adsorption capacity for many inorganic pollutants, like heavy metals. This study determines the enrichment factors of Fe, Μη, Ni, Co, Pb and Cd in Fe-Mn concretions collected from imperfectly -drained soils in Central Greece. The data show that the concretions absorbed significant amounts of heavy metals and especially of lead and cadmium from the soil system. According to the enrichment factors, the affinity of heavy metals for the concretions due to the charged surfaces of iron and manganese oxides, follow the order Pb>Cd>Mn>Co>Ni>Fe. McKenzie (1980) also found adsorption of cobalt, manganese, nickel and lead at the same order on nine synthetic manganese oxides while Nimfopoulos et al. (1997) showed that the mobility of the metals at karst cavities enriched with Mn oxides followed the order Na>K>Mg>Sr>Mn>As>Zn>Ba>AI>Fe>Cu>Cd>Pb.