Availability Of Cu Research Articles

Competitive ligand exchange between Cu–humic acid complexes and methanobactin

Copper has been found to play a key role in the physiology of methanotrophic micro-organisms, and methane oxidation may critically depend on the availability of Cu. In natural environments, such as soils, sediments, peat bogs, and surface waters, the presence of natural organic matter (NOM) can control the bioavailability of Cu by forming strong metal complexes. To promote Cu acquisition, methanotrophs exude methanobactin, a ligand known to have a high affinity for Cu. In this study, the capability of methanobactin for Cu acquisition from NOM was investigated using humic acid (HA) as a model substance. The kinetics of ligand exchange between Cu-HA and methanobactin was observed by UV-vis spectroscopy, and the speciation of Cu bound to methanobactin was determined by size-exclusion chromatography coupled to an ICP-MS. The results showed that Cu was mobilized from HA by a fast ligand exchange reaction following a second-order rate law with first-order kinetics for both methanobactin and Cu-HA complexes. The reaction rates decreased with decreasing temperature. Equilibrium experiments indicated that methanobactin was not sorbed to HA and proved that methanobactin is competitive with HA for Cu binding by forming strong 1:1 Cu-methanobactin complexes. Consequently, our results demonstrate that methanobactin can efficiently acquire Cu in organic-rich environments.

Chemical Forms and Bioavailability of Cu, Zn, Ni and Cd in Fly Ash and Calcium Oxide Stabilized Sewage Sludge

Coal fly ash at 10 and 35% (m/m) was mixed with dewatered sewage sludge (on fresh weight basis) and then the ash-sludge mixture was mixed separately with 1 and 2% (m/m) calcium oxide to kill the entrained pathogens and to suppress the availability of heavy metals enriched in sludge. A sequential extraction method was used to determine chemical forms of Cu, Zn, Ni and Cd in the sludge and fly ash and CaO stabilized sludge. A loamy acid soil amended with sludge and stabilized sludge was used to grow corn under greenhouse conditions. The results showed that sewage sludge amended with coal fly ash and CaO could reduce the availability of Cu, Zn, Ni and Cd in the sludge. Increasing fly ash and CaO amendment rate significantly increased pH and reduced DTPA extractable Cu, Zn, Ni, Cd contents and EC of the sludge. Fly ash and CaO addition significantly reduced the Zn and Cd concentration in exchangeable and total fraction. But add CaO significantly increase the Cu concentration in exchangeable fraction. Majority of Cu was associated with organic form, but Zn and Ni were associated with Fe-Mn oxide and residual forms. Fly ash and CaO addition significantly increase the percentage of Zn and Ni in residual fraction. Addition of 10% fly ash amended sludge and 10% fly ash then 1% CaO amended sludge significantly increased the dry weight yield and decreased the concentrations of Zn, Cu and Cd in shoot of corn. The results demonstrate the beneficial effects of fly ash and CaO addition on suppress the availability of heavy metals enriched in the sludge.

Content of available forms of some micronutrients in soil after long-term differentiated fertilization

The objective of this study has been to follow modifications in the content of Cu, Zn and Mn in the topmost layer of soil which had been fertilized for many years with farmyard manure and mineral fertilizers or with mineral fertilizers alone. Soil samples were collected in 2002-2005 from a trial established in 1986 on proper brown podsolic soil, according to the random block design with four replication. The first factor consisted of organic fertilization (manure applied every two years or without manure). The second factor involved different rates of mineral fertilization. Rates of nutrients in the mineral fertilizers were identical in both experimental series – with or without manure. In each year, the same crop was grown on both fields, in a crop rotation system: sugar beet (2002), spring barley (2003), maize (2004) and spring wheat (2005). Plant available forms of nutrients were extracted from soil in 1 mol HCl dm -3 solution. After extraction, the content of metals was determined by atomic absorption spectrophotometry. The results underwent statistical processing using analysis of variance for a two-factor experiment. The content of available forms of copper, zinc and manganese in soil regularly amended with manure was evidently higher than analogous concentrations determined in soil receiving only mineral fertilization since 1986. Manure most strongly improved the concentration of Cu (nearly 1.7-fold), while producing the weakest influence on manganese (over 1.3-fold more). In absolute values, however, the increase in availability of manganese was the highest, reaching on average 52 mg kg -1 of soil. Differentiated mineral fertilization with nitrogen or potassium as well as manganese and liming to a lesser extent than manure modified the availability of Cu, Zn and Mn in soil. Among these nutrients, nitrogen most often increased the content of plant assimilable forms of metals in soil, which may have been caused by its acidifying influence.

Fate and Mobility of Copper in Soil of Cocoa Plantations in Two Southwestern States of Nigeria Treated with Copper-Based Fungicides

Soils from cocoa plantations treated with Boudreaux mixture in two southwestern states of Nigeria were collected at different depths, 0–15 cm and 15–30 cm, and subjected to five-stage sequential extraction to obtain the speciation forms of copper: exchangeable, carbonate, manganese and iron oxides, organic and residual fractions. The Cu content in the extracts from the sequential extraction was read with an Atomic Absorption Spectrophotometer (AAS). The total Cu content of the soil and the physicochemical parameters of the soils were also determined. The results from the study showed that the soils had high organic matter and copper is mostly bounded to the more mobile exogenic phase much more than the stable lithogenic phase, indicating higher mobility. Within the exogenic species, carbonate fraction was the highest followed by the organic bound and the exchangeable fraction in decreasing order. Cu was not detected in the Fe/Mn bound fraction. The implication is that the fate of the administered Cu-based pesticide is more in the relatively stable carbonate bound species than the other, more mobile phase. The results showed variation in the distribution of the copper species from one depth to another. The most transported metal from the surface to the lower layer is the exchangeable fraction. The carbonate bound species is less mobile and is not readily transported into the bottom soil layer. The organic bound Cu has nearly equal distribution between the top and bottom soils and there was little or no transport of the residual metal specie from the top to the bottom. The existence of copper in the soil largely in the anthropogenic (exogenous) phase is not the most desirable for the ecosystem. This may increase the availability of Cu in the cocoa plant and bean and may lead to potential exposure risk.

Content of available Cu, Zn and Mn in soil amended with municipal sewage sludge

Municipal sewage sludge is an unavoidable byproduct of the contemporary live and business activities of people. Proper handling and utilization of sewage sludge continue to create serious problems in Poland although this waste product is a source of both organic carbon and macronutrients. The present study has been carried out in order to assess the influence of municipal sewage sludge on the content of available forms of Cu, Zn and Mn in soil. A microplot experiment set up according to the random sub-block method was conducted in 2005-2008. The experiment was established on anthropogenic, humic urban soil developed from loamy sand rich in phosphorus and magnesium, but poor in potassium, and alkaline in reaction. The design of the trials comprised 5 doses of municipal sewage sludge from the £yna Municipal Wastewater Treatment Plant in Olsztyn: 0, 70, 140, 210 and 280 Mg ha –1 of fresh matter. The tests have demonstrated that a dose of sewage sludge had a significant effect on the content of available forms of Cu, Zn and Mn in soil. In alkaline soil, however, the observed increase in the content of available forms of Cu, Zn and Mn was not hazardous to the environment, but could improve the plant nutrition with these elements. It is highly probable that the availability of Cu may increase in the second and third year after the application of sewage sludge. The accumulation of soluble Zn in soil started to decrease in the second year, but did not become significantly limited until four years after sewage sludge application. Sewage sludge raised the amount of soluble manganese in soil during the first three years, but in the final year of the experiment the quantity of soluble Mn in soil did not undergo any significant fluctuations.

Transfer of Copper, Lead and Zinc in Soil–Grass Ecosystem in Aspect of Soils Properties, in Poland

The total metal concentrations in soil samples from polluted area (roadside soils) ranged from 13.87 to 195.76mg/kg for Cu; 13.56-310.17mg/kg for Pb and 18.43-894.11mg/kg for Zn and they were, respectively about 5, 2 and 13times above the corresponding values in soil samples from country area. The mean values of EDTA-extractable concentrations in soil samples at unpolluted sites were: 2.47mg/kg for Cu, 6.33mg/kg for Pb and 4.94mg/kg for Zn. The highest concentrations of Cu, Pb and Zn in grass were measured in soils from polluted area. Higher values of proportions of EDTA-extractable metals (24% for Cu, 40% for Pb and 38% for Zn) indicate that anthropogenic metals were more mobile and bioavailable than the same metals in soils from unpolluted area (20, 16 and 20% for Cu, Pb and Zn, respectively). The availability of Cu, Pb and Zn are affected by soil properties such as pH, organic matter content and cation exchange capacity. Correlation between the EDTA-extractable forms concentrations of metals and the total concentration in the various soils was observed. The coefficients of determination (R(2)) varied between 0.809 for Cu; 0,709 for Pb and 0.930 for Zn in polluted soils and they are higher than corresponding values in unpolluted soils.

Ammonia volatilization and availability of Cu, Zn induced by applications of urea with and without coating in soils

Abstract Ammonia volatilization and the distribution of Cu and Zn were investigated in two types of soil treated with coated and uncoated urea. The rate of ammonia volatilization in two weeks after fertilizing with coated urea was 8% in soil 1 (soil derived from river alluvial deposits in Dongting Lake Plain) and 5.15% in soil 2 (red soil derived from quaternary red clay), about half the rates observed when fertilizing with common urea, implying that the hydrolysis speed of the coated urea was lower than for common urea, and that the coated urea can increase nitrogen use efficacy. As for the availability of Cu and Zn, their concentrations decreased in the first week after fertilization, and then increased, which was contrary to the effect of treatment on soil pH. For example, when the pH was 7.99, there was 0.79 mg/kg exchangeable Cu and 0.85 mg/kg exchangeable Zn in the soil derived from river alluvial deposits in Dongting Lake Plain. However, the concentrations of exchangeable Cu and Zn were generally lower for the common urea treatments than those with the coated urea because the peak pH for the common urea treatment was greater. The concentrations of these elements correlated well with pH in the range 4-8 in second order polynomial fits.

Assessment of micronutrient extractants from soils of Paraná, Brazil

In Brazil, plant-available micronutrients in the soil can be determined by several chemical extractants, the most common of which are dilute acid and chelating solutions. The purpose of this study was to assess the extractants 0.1 mol L-1 HCl, Mehlich-1, Mehlich-3 and DTPA for analysis of the micronutrients Cu, Zn, Fe, and Mn in soils from the state of Paraná. In samples from 12 soils (0-20 cm layer), wheat was planted (Triticum aestivum), grown for 42 days after emergence, and then bean (Phaseolus vulgaris) for 38 days. At the end of each planting period, the soil was sampled again. All extractants tested to assess the availability of Cu, Zn, Fe, and Mn correlated with each other. The efficiency of the extractants HCl, Mehlich-3 and DTPA in assessing plant-available Cu was similar, unlike Mehlich-1, which proved less efficient. The extractants HCl, Mehlich-1 and Mehlich-3 were less efficient in estimating plant-available Zn and Fe, and the most indicated extractant is DTPA. The efficiency of the extractants HCl, Mehlich-1, Mehlich-3 and DTPA in assessing plant-available Mn in soils from Paraná was similar.

Availability of Cu and Zn in an acidic sludge-amended soil as affected by zeolite application and liming

Acidic soils exhibit high trace element availability compared to neutral pH soils, and thus, when trace metals are added (e.g. due to sewage sludge application), measures should be taken to reduce their mobility. In this experiment, we tested two such methods, liming and zeolite addition. The aim was to measure the availability, in ryegrass (Lolium perenne L.), of heavy metals (Cu and Zn) added to soil with sewage sludge in both acidic and limed soil. Thus, in this pot experiment, we used a soil at two pH values (original soil at pH 3.56 and limed to 6.5), two rates of sewage sludge (0 and 50 Mg ha−1) and three rates of zeolite (0, 2 and 5 Mg ha–1, referred to as Z-0, Z-1 and Z-2, respectively). We found that metal concentrations in plant decreased significantly with liming but zeolite did not further reduce metal levels. In metal extractions with DTPA, zeolite additions reduced metal concentrations. In the second sampling time (on day 100), metal levels were significantly reduced at Z-0 and Z-1 compared to day 50, but at Z-2, metals were either only slightly reduced or even unchanged. We concluded that zeolite hindered metals from being strongly and irreversibly bound onto soil colloids. Zeolite at Z-2 kept metal availability relatively high over time, while metal availability at Z-0 and Z-1 was being reduced due to liming.

Cu2+-Induced Micellar Charge Selective Fluorescence Response of Acridine Orange: Effect of Micellar Charge, pH, and Mechanism

Photophysical properties of cationic Acridine Orange (AO) have been studied in different micellar environments [anionic SDS (sodium dodecyl sulfate), nonionic TX (TritonX-100), and cationic CTAB (cetyl trimethyl ammonium bromide)] at different pH, in the presence of a metal ion (Cu(2+)). At pH ∼ 8, addition of Cu(2+) results in AO fluorescence quenching in the presence of SDS micelle, enhancement of the same in the presence of TX micelle, and remaining unaltered in the presence of CTAB micelle. At pH ∼ 2, addition of Cu(2+) results in AO fluorescence quenching only in the presence of SDS micelle, and it remains mostly unaffected in the presence of TX and CTAB. Availability of Cu(2+) toward AO and binding of Cu(2+) with AO at the charged micellar interface are responsible for this pH-dependent Cu(2+)-mediated micellar charge selective fluorescence pattern.

Deep-Sea Mining: Economic, Technical, Technological, and Environmental Considerations for Sustainable Development

AbstractMining of minerals such as polymetallic nodules from the deep-sea floor has been “on-hold” as a result of several factors such as current availability of Cu, Ni, Co and Mn from terrestrial sources and their fluctuating prices. Nonetheless, exploration for new resources from deep-sea areas and development of technologies for deep-sea mining have been progressing consistently. These, coupled with recent projections of deep-sea minerals as the alternative source for metals and granting of licenses for exploration and mining of seafloor massive sulfides to private entrepreneurs, indicate the continuing interest and support the perception that such deposits may serve as sources of metals in the 21st century. However, there are several considerations for the sustainable development of deep-sea mining.A typical area of 75,000 km2 with an estimated nodule resource of >200 million tonnes is expected to yield about 54 million tonnes of metals (Mn + Ni + Cu + Co), and the gross in-place value of the metals is estimated to be ∼$21‐42 billion (depending upon the annual rate of mining) in the 20-year life span of a mine site. The decision on the timing to resume mining of these deposits will be based on the prevalent metal prices and rate of returns on the estimated investment of $1.95 billion as capital expenditure and $9 billion as operating expenditure for a single deep-sea mining venture.In view of high investment, technological challenges and economic considerations, private-public cooperation could be an effective means to make deep-sea mining a success. This paper analyzes the current status and discusses the economic, technical, technological, and environmental issues that need to be addressed for sustainable development of deep-sea minerals.

Enhancement of Copper Availability and Microbial Community Changes in Rice Rhizospheres Affected by Sulfur

The role of sulfur on the availability of Cu and the bacterial community in rice rhizospheres was investigated by pot experiments. With sulfur addition, pH in rhizosphere soil decreased and Mg(NO3)2 extractable Cu increased significantly. The bacterial community composition also changed with sulfur addition. Some specific clones having high similarity to Thiobacillus, which indicated that sulfur oxidation in the rice rhizosphere could increase the availability of Cu. These results suggested that sulfur source which could provide substrate to sulfur oxidizing bacteria and enhance the availability of Cu was not a suitable sulfur fertilizer for Cu polluted soil.

Reduction of the short-term availability of copper, lead and zinc in a contaminated soil amended with municipal solid waste compost

The effect of two municipal solid waste composts on the availability of Cu, Pb and Zn in a soil contaminated in the laboratory was evaluated. An agricultural acid soil developed on granite was amended with the composts at two rates (3% and 6% dry weight), contaminated with 1000 mg kg −1 of Cu, Pb and Zn, and incubated in the laboratory for three months. Determinations of soil pH, CaCl 2-extractable and EDTA-extractable Cu, Pb, and Zn were run monthly during the incubation. At the end, a leaching test (TCLP) and selective extractions were performed for these elements. The analysis of the CaCl 2-extractable elements demonstrated a strong capacity of both composts to decrease the solubility of the metals added to the soil, specially for Cu and Pb. The percentage of reduction of the soluble forms with respect to the initial addition was higher at the highest rate of compost, and reached 99% for Cu and Pb, and 80% for Zn in the compost-amended soil, whereas the soil without amendment was able to reduce Cu availability by a 94%, but not Zn or Pb availability. The TCLP test showed that compost also reduced the leachability of the three elements. Nevertheless, EDTA extracted a major amount (around 90%) of the elements added in all the treatments. Given that EDTA has a strong ability to extract elements bound to organic matter, it can be hypothesized that the main mechanism of the observed insolubilization was the formation of low-solubility organo-metallic complexes with both soil and compost organic matter. The selective extractions confirmed that compost reduced the exchangeable fraction of the elements, and that the organically bound fraction (pyrophosphate-extractable) was the main one for the three elements.

SORPTION-DESORPTION CHARACTERISTICS OF HEAVY METALS AND THEIR AVAILABILITY FROM THE SEDIMENT OF SEGARA ANAKAN ESTUARY

Estuarine sediments are increasingly recognized as both a carrier and a possible source of heavy metals in pollution of aquatic ecosystems. The bioavailability of heavy metal from sediments, however, is a long-standing impediment of questions in determining the metal effects in ecosystems. The fraction considered as available heavy metal are both the dissolved heavy metal and the exchangable cations. The main objective of this study is to understand the extent of heavy metal availability from sediments in estuarine ecosystem. It was found that the availability of heavy metals, i.e. copper, zinc, cadmium, and mercury in the estuarine ecosystem investigated, are governed by the relative strength of the electrostatic attraction of their complexation to the ligands present both in the sediment and the overlaying waters. Under simulated estuarine ecosystem, it was observed that Cu and Zn prefer to form organo-complex through ligand exchange, while Cd and Hg tend to form chloro-complex through electrostatic interaction. Therefore, the availability of Hg and Cd is higher in more saline overlaying water. On the contrary, the availability of Cu and Zn is lower in more saline overlaying waters, as indicated by their respective water-sediment distribution coefficient, KD. Similar behaviour of heavy metal was observed in natural field conditions of Segara Anakan estuary. Due to the higher salinity of the overlaying water, the availability of Cd and Hg in dry season was higher than in wet season, while Zn was more available in wet season due to the higher input of organic matters from the inland. The patterns of heavy metal release from the sediment are consistent to that obtained in experiments of the undisturbed simulation, where highest release was obtained for Cd. Surprisingly, it was found that even though Cd was not detected in the sediment, higher level of Cd in water medium was observed in dry season, and Cu seems to retain in the sediment in both dry and wet seasons. Compared to the unextractable fraction, the extractable was very low, therefore Geloina sp. was used as biomonitor for dissolved Cd and Hg, and Zn in sediment. Generally, the heavy metal concentration in Geloina sp. was higher in dry season than in wet season, but no Cu uptake was detected. Therefore, the establishment of limit values of heavy metals in sediment is highly recommended. Keywords: heavy metal, sorption-desorption, estuary, availability.

Heavy metal contaminations in a soil–rice system: Identification of spatial dependence in relation to soil properties of paddy fields

In order to identify spatial relationship of heavy metals in soil–rice system at a regional scale, 96 pairs of rice and soil samples were collected from Wenling in Zhejiang province, China, which is one of the well-known electronic and electric waste recycling centers. The results indicated some studied areas had potential contaminations by heavy metals, especially by Cd. The spatial distribution of Cd, Cu, Pb and Zn illustrated that the highest concentrations were located in the northwest areas and the accumulation of these metals may be due to the industrialization, agricultural chemicals and other human activities. In contrast, the concentration of Ni decreased from east to west and the mean concentration was below the background value, indicating the distribution of Ni may be naturally controlled. Enrichment index (EI) was used to describe the availability of soil heavy metals to rice. The spatial distribution of EIs for Cd, Ni and Zn exhibited a west-east structure, which was similar with the spatial structures of pH, OM, sand and clay. Cross-correlograms further quantitatively illustrated the EIs were significantly correlated with most soil properties, among which; soil pH and OM had the strongest correlations with EIs. However, EI of Cu showed relative weak correlations with soil properties, especially soil pH and OM had no correlations with EI of Cu, indicating the availability of Cu may be influenced by other factors.

Disponibilidade de Cu, Pb e Zn nas áreas mineiras de Canal Caveira e São Domingos – Faixa Piritosa Ibérica

Several mining areas are abandoned in the Iberian Pyrite Belt (IPB) leading to important points of environmental con­tamination. The potential and immediate environmental risk and impact on public health of hazardous elements from soil can be estimated from availability analy­sis. The aim of this study was to evaluate the availability of Cu, Pb and Zn in Sao Domingos and Canal Caveira mining ar­eas located in the IPB. Both mining areas had high soil ele­mental total concentrations. Metals avail­ability changed with plots and, is related with soils characteristics. In Canal Caveira mine area, the Pb available frac­tion in soils was higher than in Sao Domingos soils however, the opposite was observed for Zn. The fractions of available Cu, in both mine soils, are <0.6 % of the total concentration. In both min­ing areas, Cu and Zn are mainly associ­ated with the residual fraction, while Pb is associated with residual fraction in Sao Domingos and with organic matter in Ca­nal Caveira soils.

Disponibilidade de cobre e zinco em solos do sul do Brasil

O estudo da eficiência de soluções extratoras multielementares para avaliação da disponibilidade de nutrientes do solo às plantas tem aumentado. O uso dessas soluções aumenta a eficiência dos laboratórios de análise de solo devido à redução de procedimentos analíticos. Além disso, a determinação de nutrientes por espectrometria de emissão ótica por plasma induzido (ICP-OES) tem aumentado nos últimos anos, visando principalmente à redução dos procedimentos analíticos e dos limites de detecção. Com os objetivos de selecionar métodos de extração e verificar a eficiência para avaliar a disponibilidade de Cu e Zn para as plantas, foram realizados estudos em casa de vegetação e em laboratório. Em casa de vegetação, amostras de solos representativos do Estado do Rio Grande do Sul foram cultivadas, em vasos de 11 dm³ (a céu aberto), com plantas de milho (Zea mays), por 45 d e, em sequência, com soja (Glycine max), por mais 45 d. Os métodos estudados para extração de Zn e Cu foram: HCl 0,1 mol L-1 (HCl), Mehlich-1 (M1) e Mehlich-3 (M3). Os coeficientes de determinação obtidos entre as quantidade de Cu absorvida pelas plantas e o extraído pelos diferentes métodos foram: HCl = 0,56**, M1 = 0,35*; M3 = 0,46** para as plantas de milho; e HCl = 0,66**, M1 = 0,43*, M3 = 0,93** para as de soja. Para o Zn absorvido pelas plantas e o extraído pelos diferentes métodos, foram: HCl = 0,18*, M1 = 0,32**, M3 = 0,10* e HCl = 0,37*, M1 = 0,36**, M3 = 0,31*, respectivamente para as plantas de milho e de soja. Os métodos tiveram baixa capacidade preditiva na avaliação da disponibilidade de Cu e de Zn para as plantas.

Heavy metal fractionation during the co-composting of biosolids, deinking paper fibre and green waste

Due to the introduction of the European Union Landfill Directive, composting has become a potentially viable disposal route for some organic wastes. As waste-derived compost is frequently added to soil to improve soil quality, it is important to quantify the environmental risk posed by potentially toxic elements contained within it. Here we used a sequential chemical extraction procedure to investigate the temporal dynamics of heavy metals (Cu, Zn, Pb and Ni) during the co-composting of biosolids, deinking paper fibre and green waste. Overall, composting over 26 weeks reduced the availability of Ni, had no effect on Pb and slightly increased the availability of Cu and Zn. We conclude that although the total Cu and Ni concentrations in the compost exceed legislative guidelines for land application, due to their recalcitrant nature within the compost, this compost posed very little threat to soil or plant quality if used in agriculture or land restoration.

콩나물의 재배기간에 따른 NDF에 결합된 미량 무기질의 변화와 추정이용률

Dept. of Aquaculture, Pukyong National university, Busan 607-737, KoreaAbstractThis study was conducted to determine contents and estimated availabilities of trace minerals (Cu, Fe, Mn, Zn) in soybean sprouts depending on culture periods such as 1, 3 and 5 days. The proportional changes of Cu estimated availability in cotyledon were between 57.31 and 98.34%, between 63.69 and 82.56% for Fe, 99.19 and 99.82% for Mn and 48.60 and 94.56% for Zn, respectively, based on dry matter. The estimated availabilities of Cu, Fe, Mn, and Zn in hypocotyl were between 34.63 and 56.0%, 20.74 and 40.33%, 86.5 and 95.88%, and 96.11 and 96.61%, respectively, on dry matter basis.Key words: estimated availability, NDF, trace minerals, soybean sprouts, cotyledon, hypocotyl

Heavy metal contamination of soils and tea plants in the eastern Black Sea region, NE Turkey

The study area covers two geologically different regions which have intensively been carpeted by tea plants in the eastern Black Sea. The rocks exposed in the region contain considerable amount of trace metals due to Upper Cretaceous massive sulfide formations and tertiary epithermal mineralizations. Tea plants that grow in soils derived from such mineralized rocks contain different concentrations of Cu, Pb, Zn, Fe, Cd, P, Al, Na, K, and S. The content ratios of most of the analyzed elements except Al are higher in basaltic and sedimentary rocks. To describe the transfer of metals from soil to tea leaf, the Freundlich-type model (log c plant = ac soil + log b) is used. The metal concentrations in leaves of tea plant in the studied soils are ranked as Zn > Cu > Pb > Al > Cd > Fe. The capacity of the plant to affect the metal accumulation decreased as follows: Fe > Cd > Pb > Cu > Zn > Al. Negative correlations were found between pH and availability of Cu, Pb, Zn, Mn, and Al elements by the tea plant. Experimental applications indicated that tea plant leaves growing on soils with high metal contents show some signs of toxicity. In soils where, particularly, ammonium sulfate fertilizer is used, metal uptake by the tea plant was found to be significantly higher as a result of extremely acidic character of the soil.