Study of Zn,Cu and Pb content in plants and contaminated soils in Sardinia

Trace elements in soils exist as components of several different fractions. We have analyzed the correlation between total and extractable (EDTA, calcium chloride and deionized water) Zn, Pb and Cu concentrations in soils and the concentration of these elements in plant leaves. Soil and plant samples have been taken from Sulcis-Iglesiente (Sardinia), an area rich in mining tailings. This has made that the concentrations of the trace element under study in soils were varied. Three plants have been studied: Dittrichia viscosa, Cistus salviifolius, and Euphorbia pithyusa subsp. cupanii. Soil samples beneath each of them at depths of 0–30 and 30–60 cm have been considered. The highest concentration of trace elements in the leaves of the studied species has been found for Zn. The calcium carbonate content and the crystalline and amorphous forms of iron in the soil have determined the concentration of metal in plant leaves. The soil concentrations that have been found with the extraction methods are uncorrelated with Pb and Cu concentrations in plants, but Zn is correlated with the fraction extracted with EDTA and calcium chloride. The concentrations of trace metals in plants are most closely related to the soil contents of CaCO₃, electrical conductivity, Fe_ox, and Fe_dc.     

Influence of acid rain and ozone on soil heavy metals under loblolly pine trees: A field study

A field growth chamber study was conducted to determine the effects of ozone and simulated acid rain (SAR) on soil heavy metals. Loblolly pine (Pinus taeda L.), grown in open-top chambers, was exposed to three concentrations of ozone (charcoal filtered air with 0.026 µL O₃ L^-1, and two non-filtered treatments in which ozone concentrations were 0.074 µL L^-1 and 0.147 µL L^-1, respectively) and two levels of SAR (pH 3.5 and 5.2). Ozone was applied for 12 h d^-1 for 9 months and acid rain deposition was 125 mm event^-1. After 9 months exposure, soil pH, organic matter and DTPA-extractable heavy metals (Cd, Pb, Zn, Mn, Fe, Cu) were determined on soil samples collected from exposed chambers at two depths (0–15 cm and 15–30 cm). Simulated acid rain decreased the original soil pH. The concentrations of Cd, Pb and Mn at SAR pH 3.5 were significantly higher than at SAR pH 5.2. Ozone did not affect Zn, Fe and Cu, but a significant interaction between pH and O₃ on Mn, Pb and Cd was observed. Due to the poor drainage capacity of this soil, leaching of heavy metals was not observed.     

Effect of Namomaterials on Heavy Metal Transport in Alkaline Soil

A high level of heavy metals in soil would negatively impact human health if these metals are consumed by humans through the food chain. The effect of nanomaterials, including SiO₂-Al₂O₃-Fe₂O₃, on heavy metals in alkaline soil was studied through simulating leaching in the soil column. Nanomaterials that weighed 4%, 6%, and 10% of the soil mass were added to a soil column in which garlic was planted. Leaching tests were conducted. Heavy metals in the soil leachate of different soil depths and different parts of the plant planted in the soil column were determined using a high-resolution inductively coupled plasma mass spectrometer (HR-ICP-MS). The results indicated that the migration of heavy metals through alkaline soil was inhibited. In the test with nanomaterials of 4% soil mass, 63% Cu, 79% Cd, 68% Pb, 89% Zn, and 76% Ni were decreased compared to the control. When the addition of nanomaterials was up to 6% of soil mass, 82% Cu, 92% Cd, 76% Pb, 91% Zn, and 88% Ni were reduced, respectively. No additional apparent results were observed with more nanomaterials added to the soil column. The nanomaterials effectively prevented heavy metal migration, especially inhibiting heavy metal migration downward. Nanomaterials will be promising in subsequent studies.     

Occupational exposure of foundry workers assessed by the urinary concentrations of 18 elements and arsenic species

BackgroundSome raw materials applied in Fe foundry industries may contain potentially toxic elements. Thus, foundry worker’s occupational exposure is a constant health concern.MethodIn this study, 194 urine samples from foundry workers were analyzed by inductively coupled plasma mass spectrometry for biomonitoring of Al, As, Ba, Cd, Co, Cr, Cs, Cu, Fe, I, Mn, Ni, Pb, Sb, Sn, Se, U and Zn. Moreover, arsenic speciation was performed in representative samples of production sector workers (group A) and administration sector workers (group B).ResultsConcentrations of As, Pb, Cd, Cu, Cs, I, Sb in urines from group A were higher than those found for group B. Samples of group A presented Cs, Ni, Mn, Pb, U and Zn concentrations higher than values reported for exposed workers assessed by other studies. Forty-four samples from group A exceed As-reference limits. Group A had approximately seven times more inorganic As (as arsenite) and 14 times more organic As (as dimethyl As) than group B. A statistically significant difference was observed in the elemental concentration in the workers' urine by the time in the function. Moreover, alcohol consumption is probably influencing the urine concentration of As, Ba, Cd, Co, Cu, Fe, I, Se and Zn.ConclusionThe monitored foundry workers are exposed to potentially toxic elements and more attention must be given to their health. Therefore, workplace safety conditions must be improved, and constant biomonitoring is necessary to ensure workers' health.     

Factors Controlling the Geochemical Partitioning of Trace Metals in Estuarine Sediments

The geochemical partitioning of trace metals in sediments is of great importance in risk assessment and remedial investigation. Selected factors that may control the partitioning behavior of Cu, Pb and Zn in non-sulfidic, estuarine sediments were examined with the use of combined sorption curve—sequential extraction analysis. This approach, which has not been previously used to examine estuarine sediments, allowed determination of sorption parameters for Cu, Pb and Zn partitioning to individual geochemical fractions. Partitioning behavior in sulfidic sediments was also determined by sequentially extracting Cu, Pb, and Zn from synthetic sulfide minerals and from natural sediment and pure quartz sand after spiking with acid-volatile sulfide (AVS). Trace metal sorption to the “carbonate” fraction (pH 5, NaOAc extraction) increased with metal loading due to saturation of sorption sites associated with the “Fe-oxide” (NH₂OH·HCl extraction) and “organic” (H₂O₂ extraction) fractions in non-sulfidic sediments. Freundlich parameters describing sorption to the “Fe-oxide” and “organic” fractions were controlled by the sediment Fe-oxide and organic carbon content, respectively. Sequential extraction of Cu from pure CuS, AVS-spiked sediment and AVS-spiked quartz sand showed that AVS-bound Cu was quantitatively recovered in association with the “organic” fraction. However, some AVS-bound Pb and Zn were recovered by the NH₂OH·HCl step (which has been previously interpreted as “Fe-oxide” bound metals) in the sequential extraction procedure used in this study. This indicates that the sequential extraction of Pb and Zn in sulfidic sediments may lead to AVS-bound metals being mistaken as Fe-oxide bound species. Caution should therefore be exercised when interpreting sequential extraction results for Pb and Zn in anoxic sediments.     

Accumulation characteristics of heavy metal Pb, Cu, Zn in Wanggang tidal flat based on Renyi theory

The vertical accumulation of heavy metals and the pollution status in Wanggang China tidal flat were studied. The base value of 210Pb in Wanggang area was obtained as 1.16 dpm/g. The fractal theories were led into the quantitative study of pollution issues. The modern average deposition rate in Wanggang area is 4.13 cm/a, according to the ²¹⁰Pb analysis. Through the correlation analysis between heavy metals, it is educed that the Fe, Cu, Pb, Zn and Li have better correlation coefficients in the area. After normalization, the nomalization values of Cu and Zn remain stable in the past 15 years. Cu shifts its value from 0.4 to 2, and Zn from 1.5 to 2.6. The information dimension of the normalized heavy metals is high in the area with loose systematic structure and lower organizational degree. The fractal dimension value of Zn moves from 3 to 6.5 with an average of 4.68; contemporary Cu from 5 to 6.5 with an average of 5.8085. The study shows that the heavy metal distribution in the area is mainly controlled by local geochemistry character with limited contribution from human activities. Meanwhile, the fractal dimension value of Pb normalization is lower, and its fractal dimension varies from 2 to 5.5 with an average of 3.608. Higher levels of self-organization of Pb mean a certain degree of lead contamination.     

Accumulation characteristics of heavy metal Pb, Cu, Zn in Wanggang tidal flat based on Renyi theory

The vertical accumulation of heavy metals and the pollution status in Wanggang China tidal flat were studied. The base value of 210Pb in Wanggang area was obtained as 1.16 dpm/g. The fractal theories were led into the quantitative study of pollution issues. The modern average deposition rate in Wanggang area is 4.13 cm/a, according to the ²¹⁰Pb analysis. Through the correlation analysis between heavy metals, it is educed that the Fe, Cu, Pb, Zn and Li have better correlation coefficients in the area. After normalization, the nomalization values of Cu and Zn remain stable in the past 15 years. Cu shifts its value from 0.4 to 2, and Zn from 1.5 to 2.6. The information dimension of the normalized heavy metals is high in the area with loose systematic structure and lower organizational degree. The fractal dimension value of Zn moves from 3 to 6.5 with an average of 4.68; contemporary Cu from 5 to 6.5 with an average of 5.8085. The study shows that the heavy metal distribution in the area is mainly controlled by local geochemistry character with limited contribution from human activities. Meanwhile, the fractal dimension value of Pb normalization is lower, and its fractal dimension varies from 2 to 5.5 with an average of 3.608. Higher levels of self-organization of Pb mean a certain degree of lead contamination.     

In-Situ Remediation of Lead–Zinc Polymetallic Mine Contaminated Soils by MnFe2O4 Microparticles

In-situ remediation is a practical approach to remediate soils contaminated with heavy metals. The MnFe₂O₄ microparticles (MM) were prepared for the in-situ remediation of contaminated soils from a lead–zinc polymetallic mine in Inner Mongolia province, China. The effects of MM dosage, pH on remediation efficiency, were determined with static vibration leaching experiment, and the release risk of heavy metals of treated soil was studied by column leaching experiment. The results showed that the leached Cu, Pb, Zn, and As concentration decreased drastically with increasing MM dosage, when the dosage was lower than 10 g/kg. Moreover, the decrease of pH caused increase of leached concentration of Cu, Pb, Zn, but slight decrease of leached As concentration. For the amended soil, concentrations of leached heavy metals were lower than Grade III limit of Chinese Environmental Quality Standards for Ground and Surface water (GB3838-2002) under simulated acid rain leaching condition. In comparison with non-amended soils, the total amount of Cu, Pb, Zn, and As release from amended soils was reduced by 93.6%, 69.2%, 57.0%, and 99.7%, respectively. The MM is a kind of promising amendment for heavy metals contaminated soil.     

Sludge-Derived Cu and Zn in a Humic-Gley Soil: Effect of Dissolved Metal-Organic Matter Complexes on Sorption and Partitioning

A sequential extraction scheme was combined with sorption isotherm analysis in order to investigate sorption of sewage sludge-derived Cu and Zn to the A-horizon of a humic-gley soil as a whole, and to the operationally defined exchangeable (1?M MgCl₂), carbonate (1?M NaOAc), Fe/Mn oxide (0.04?M NH₂OH.HCl), and organic (0.02?M HNO₃+30% H₂O₂) soil fractions. Sorption parameters were compared for a sample of sludge leachate (with 97.4% of Cu and 63.2% of Zn present as dissolved metal-organic matter complexes, as calculated by geochemical modeling involving MINTEQA2 and verified using an ion exchange resin method) with that of a reference solution exhibiting the same chemical characteristics as the leachate, except for the presence of dissolved organic material. Dissolved metal-organic matter complexes were found to significantly (P<0.05) depress sorption to the bulk soil and each fraction. The greatest depression of Cu and Zn sorption was observed for the exchangeable, carbonate, and Fe/Mn oxide fractions, while the organic fraction of the soil was the least affected. This reflects a greater affinity for the exchangeable, carbonate, and Fe/Mn oxide fractions by the free divalent metal (Cu²⁺, Zn²⁺), with sorption by these fractions attributed to cation exchange, chemisorption, and co-precipitation processes. The sorption characteristics of the organic fraction indicated that Cu and Zn sorption by soil organic matter mostly involved dissolved metal-organic matter complexes. This may be attributed to hydrophobic interactions between nonpolar regions of the dissolved metal-organic matter complexes and solid-phase soil organic matter.     

淹水条件下控释氮肥对污染红壤中重金属有效性的影响

采用淹水培养方法研究了不同氮水平(100、200和400 mg/kg,分别记为1、2、3)下普通尿素(PU)、硫包膜尿素(SCU)、树脂包膜尿素(PCU)和硫加树脂双层包膜尿素(SPCU)对污染红壤中Cd、Pb、Cu、Zn有效性的影响.结果表明,不同包膜尿素对土壤pH值和水溶性SO42-含量有较大影响.各施氮处理红壤pH值随着施氮量的增加(除5d时PU和60 d时SCU)而增加,不同包膜尿素对土壤中水溶性SO42-含量有较大影响,在同一施氮水平下不同包膜尿素处理间土壤pH值和土壤中水溶性SO42-含量差异较大.60 d培养期间PU、SCU、PCU和SPCU处理pH值比对照分别升高0.17-0.38、0.08-0.27、0.07-0.36和0.10-0.21;水溶性SO42-含量PU、SCU和PCU处理比对照分别升高39.5％-157.3％、40.9％-94.5％和7.55％-55.8％,而SPCU处理降低5.67％-90.7％.不同尿素类型和氮肥的施用量对红壤Cd、Pb、Cu和Zn有效性的影响均存在显著差异.60 d培养期间红壤有效态Cd含量以树脂包膜尿素100 mg N/kg下最低,其有效态Cd含量比对照显著降低20.7％-69.8％;有效态Pb、Cu和Zn含量以普通尿素400 mg N/kg下最低,其有效态Pb、Cu和Zn含量比对照分别显著降低17.0％-54.2％、18.5％-34.6％和15.6％-59.5％.随施氮量提高,PU处理有效态Cd含量先升高后降低,有效态Pb、Cu和Zn含量逐渐降低;SCU处理有效态Pb含量逐渐降低,有效态Cd、Cu和Zn含量变化规律不一致;PCU处理有效态Cd含量逐渐升高,有效态Pb、Cu和Zn含量变化规律不一致;SPCU处理有效态Cd、Pb、Cu和Zn含量逐渐降低.有效态Pb和Zn含量与pH值和水溶性SO42-含量呈显著负相关,有效态Cd与水溶性SO42-含量呈显著正相关.在多重金属污染红壤中,可考虑不同控释氮肥的配合使用,降低土壤中重金属的有效性.     

PHYTOEXTRACTION OF METAL POLLUTED SOILS AROUND A Pb-Zn MINE BY CROP PLANTS

In order to assess their practical capability for the absorption and accumulation of Pb, Zn, and Cu, five common crop plants, i.e. maize (Zea mays), sunflower (Helianthus annuus), canola (Brassica napus), barley (Hordeum vulgare) and White lupine (Lupinus albus) were tested in pot experiments using six soil samples taken from mine tailings, pasture and arable soils around an old Pb-Zn mine in Spain. Metal concentration ranges of the soils were 76.2–785 mg kg^?1, 127–1652 mg kg^?1, and 12.4–82.6 mg kg^?1 for Zn, Pb, and Cu, respectively. With the exception of the highest polluted sample, soil total metal concentration did not influence significantly biomass yields of each crop for the different growth substrates. The order found for the total metal accumulation rate (TMAR) in the crops was Zn>>Pb > Cu, with maize reaching the highest metal concentrations. Pb root concentrations were markedly higher than those of shoots for all the crops, while Zn and Cu were translocated to shoots more efficiently. Concentrations of metals extracted by EDTA and BCR sequential extraction were well correlated, in general, with both root metal content and TMAR. CaCl₂-extracted Zn was well correlated with root concentrations, TMAR and, in some cases, with shoot contents. Our study showed that the test crops were not feasible to remediate the heavily or moderately contaminated soils studied here in order to achieve the total metal soil concentrations required by the current European laws.     

Soil trace element changes during a phytoremediation trial with willows in southern Québec,Canada

This study determined the changes in trace elements (TE) (As, Cd, Cu, Ni, Pb, Zn) chemistry in the soils of a willow (“Fish Creek” – Salix purpurea, SV1 – Salix x dasyclados and SX67 – Salix miyabeana) plantation growing under a cold climate during a three-year trial. The soil HNO₃-extractable and H₂O-soluble TE concentrations and pools significantly decreased under most cultivars (Fish, SX67). Yet, TE changes showed inconsistent patterns and localized soil TE increases (Ni, Pb) were measured. Temporal changes in soil TE were also detected in control plots and sometimes exceeded changes in planted plots. Discrepancies existed between the amount of soil TE change and the amount of TE uptake by willows, except for Cd and Zn. Phytoremediation with willows could reduce soil Cd and Zn within a decadal timeframe indicating that they can be remediated by willows in moderately contaminated soils. However, the time needed to reduce soil As, Cu, Ni and Pb was too long to be efficient. We submit that soil leaching contributed to the TE decrease in controls and the TE discrepancies, and that the plantation could have secondary effects such as the accelerated leaching of soil TE.     

Size-dependent bioaccumulation of metals in the amphipod Gammarus zaddachi (Sexton 1912) from the River Hunte (Germany) and its relationship to the permeable body surface area

The present study aims to evaluate and verify toxicokinetic models for the bioaccumulation of Cd, Pb, Cu and Zn in the gammaridean amphipod Gammarus zaddachi (Sexton 1912) from the River Hunte (Germany). The bioaccumulation experiment was performed in a static system, taking into account the effect of body size on bioaccumulation and the relationship between toxicokinetic model parameters and the permeable body surface area of gammarids. A modified two-compartment model was employed, which was not limited to changes in both biomass of gammarids in the experiments and metal exposure concentrations; the result was a significant model fit. The parameters k ₁ and BCF decreased with increasing body length (BL) of G. zaddachi, while no such trend was observed for k ₂ among BLs ranging from 8.1 to 24.1 mm. The nonlinear relationship was successfully quantified using an inverse-sigmoid logistic model as a basis for subsequent adjustment of the toxicokinetic uptake models. Moreover, k ₁ and BCF increased with increasing specific surface area (SSA, i.e., the ratio of permeable body surface area to body volume) of gammarids. This relationship was successfully quantified using an extended Langmuir equation, which was derived by combining the inversely sigmoid logistic relationship between k ₁, BCF_Exp and BL with a single-exponential-decay relationship between SSA and BL reported previously, implying that the size-dependent bioconcentration was dominated by the SSA-related uptake. Thus, with increasing SSA, k₁ and BCF at first increased sharply, for smaller SSAs with larger BLs, but then approached saturation for larger SSAs with smaller BLs. In addition, field-to-experimental BCF ratios (BCF_Field/BCF_Exp) were determined, yielding values around 1 (indicating equality of the two BCFs) for Pb and Cd for smaller amphipods, but much higher values for larger sizes. The BCF ratios for Cu and Zn were much larger than 1 for both smaller and larger sizes. However, when seasonal changes in BL distribution of gammarids were considered, no significant differences were observed between annual ranges of BCF_Field and BCF_Exp for Pb and Cd. Considering the seasonal changes in BL distribution as well as the Cu and Zn metabolic requirements, no significant difference was observed for Cu, but still a significant one for Zn. From an ecotoxicological perspective we suggest that in the verification of toxicokinetic models not only field-to-experimental BCF ratios should be taken into account, but also several ecological factors such as the size distribution of the animal populations under study as well as, if applicable, metabolic requirements for essential elements.     

Effects of Long-Term exposure to Heavy Metals upon Rhizosphere Bacteria from Baia Mare Area (Maramureş County,Romania)

Abstract

The aim of this study was to investigate the extent of heavy metal (HM) pollution and its effect on microorganisms from rhizosphere soil in Baia Mare area (Maramure? County, Romania). Two sites with different contamination degrees were included in the study: one with a long history of mining activities and one within a drinking water safeguard zone. Rhizosphere soil samples were characterized with respect to physico-chemical parameters and the Cd, Cu, Pb and Zn contents. Native bacteria were investigated for HM tolerance and biofilm formation under toxic exposure by the microdilution assay. The most resistant strains were identified and the minimum inhibitory concentrations for HMs were determined. Cd, Cu, Pb and Zn exceeded the intervention threshold in Bozânta tailings site, while Pb content exceeded the intervention level within the area of the drinking water treatment plant. Cd showed a very high potential ecological risk in Bozânta area. The long-term exposure to HMs contributed to the selection of HM-tolerant and weakly adherent strains. Biofouling was significantly reduced under the influence of copper ions. Arthrobacter, Rhodococcus and Acidovorax strains with exceptional resistant profiles were isolated from the tailings site, indicating the important role of native microorganisms in rhizosphere ecosystems of contaminated sites.     

Assessment of Heavy Metal Accumulation in Urban Soil around Potash Industrial Site in the East of the Dead Sea and their Environmental Risks

The aim of this study was to assess the extent and severity of metal contamination of soils in the east of the Dead Sea, southwestern Jordan. This area was affected by a potash plant and intensive agricultural production. The samples were obtained at two depths, 0–10 cm and 10–20 cm, and were analyzed by atomic absorption spectrophotometry for Cu, Fe, Zn, Mn, Pb, Cd, and Cr. Physicochemical parameters that are expected to affect the mobility of metals in the soil such as pH, TOM, CaCO₃, CEC, and conductivity were determined. The relatively high concentrations of metals in soils of the studied area were related to anthropogenic sources such as the potash industry, agricultural activities, and traffic emissions. The mean concentrations of the metals were of the order: C_Fe > C_Pb > C_Zn > C_Cr > C_Mn > C_Cu and C_Cd where C is the concentration of these metals in solution. Heavy metals such as Zn, Cd, and Pb showed higher concentrations in the area that is closer to the potash plant, while Cr concentration was low. These metals were concentrated in the soil surface and decreased in the lower part of soil due to their mobility, movement and physicochemical properties, and alkaline pH. Metals of anthropogenic origin, including Cd, Pb, and Zn, were highly enriched with respect to crustal composition. The non-clay minerals of the sand-sized fraction are composed mainly of quartz and calcite as major minerals, with dolomite and feldspar as minor minerals. Factor analysis revealed three groups of elements that differ in their distribution. The first of these components is unpolluted soil, which was distributed in the study area. The second is the polluted soil, which occurs mostly around the potash plant and Ghore El-Safi area. The third factor represents the physicochemical sources, and is not significant.     

Arginine decarboxylase ADC2 enhances salt tolerance through increasing ROS scavenging enzyme activity in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

In this study, we investigated the possible role of hemin in alleviating zinc (Zn), lead (Pb) and chromium (Cr) toxicity in rice seedlings grown hydroponically by analyzing the morphological and physiological parameters. Our results showed that exposure of rice seedlings to excess Zn, Pb or Cr could cause severe leaf chlorosis, inhibit photosynthetic activity and consequently suppress plant growth. The concentration of O₂ ^?? and H₂O₂ significantly increased and the activities of antioxidative enzymes decreased in roots of rice seedlings under metal exposure. The combined treatments (hemin?+?ZnSO₄, hemin?+?Pb(NO₃)₂ and hemin?+?K₂Cr₂O₇), on the other hand, significantly enhanced the photosynthesis- and plant growth-related parameters compared with their corresponding heavy-metal-stress alone. Combined treatments dramatically stimulated the activities of superoxide dismutase (SOD), ascorbic peroxidase (APX) and glutathione reductase (GR) as well as the concentrations of ascorbic acid (AsA) and glutathione (GSH) as compared with the metal- stress alone. The concentrations of reactive oxygen species (ROS, e.g. O₂ ^?? and H₂O₂) were significantly reduced in the metal plus hemin treatments. Hemin addition also reduced metal accumulation in rice seedlings especially in root tissues. These findings suggest that hemin-elevated levels of antioxidants, activities of antioxidative enzymes and hemin-reduced accumulation of heavy-metal could confer resistance against Zn, Pb, and Cr stress in rice seedlings, resulting in improved pigments accumulation, photosynthetic attributes and plant growth.     

Influence of heavy metals in spruce forest soil on amylase activity,CO2 evolution from starch and soil respiration

Summary Starch decomposition and soil respiration is partly inhibited in spruce needle mor contaminated with heavy metals (Cu, Zn, Pb and Cd) from a brass foundry at Gusum, Southern Sweden. The total decomposition of starch was measured as CO₂ evolution rate and the hydrolysis of starch as increase in glucose concentration during incubation according to the methods of Hoffman and Pallauf and that of Nelson. In order to measure the effects of the Na-acetate buffer (pH 5.5) during incubation, amylase activity was also determined without buffer. Only the Hoffmann and Pallauf method without buffer was significantly different (p<0.001) from the other three methods. Application of stepwise regression showed that 43 to 62 per cent of the variability in amylase activity was accounted for by the metal- and hydrogen concentration of the soil. Corresponding figures for the total starch decomposition and soil respiration were 47 and 66 per cent respectively. re]19751213     

Spatial variation in a grassland on soil rich in heavy metals

Abstract. The vegetation in a grassland area in the prefecture of Kilkis (N. Greece), known for its surface Cu-mineralization, was studied. 43 quadrats were established along a transect through an area where the vegetation formed patches of different size. Cover-abundance and frequency estimates for all species were made. Normal Association Analysis revealed five quadrat groups characterized by Trifolium scabrum, Linaria pelisseriana, Anthoxanthum ovatum, Gypsophila muralis and Minuartia hirsuta ssp. falcata. 43 soil samples were analysed for pH, organic C, CaCO₃, total content of Fe, Zn, Pb, Cu, Mn, Ca, Mg, K, Na and soil texture. From a discriminant analysis performed on soil data five soil groups resulted, which are highly related to the five vegetation groups. Thymus sibthorpii, Minuartia hirsuta ssp. falcata and Rumex acetosella are the most important taxa with respect to physiognomy and patchi-ness of the vegetation. The number of species in each group of quadrats is affected by the relative favourableness or severity of the soil conditions. Metal contents, mainly Zn, Cu, Mg and Na, and soil texture are considered to be among the main factors controlling the structure and physiognomy of the vegetation.     

Dynamics of trace metals in the system water – soil – plant – wild rats – tapeworms (Hymenolepis diminuta) in Maglizh area,Bulgaria

BackgroundThe impact of chemical elements on the biosphere is a function of their concentration and chemical form. Elucidation and prognosing of the latters in water basins and soil extracts is of particular significance for the assessment of their bioaccumulation in plants and animals.ObjectivesTrace metals dynamics in the system water – soil–plant–wild rats – Hymenolepis diminuta in two agro-industrial zones (East and West) around Maglizh city, Bulgaria were investigated through experimental studies and thermodynamic modelling of the chemical species.MethodsSamples from surface waters of rivers, their nearby uncultivated soils, meadow uncultivated vegetation (Ranunculus acris and Gramineae) and field rats were collected. In situ measurements and laboratory analyses were performed for the determination of the physico-chemical characteristics and total concentrations of Al, Fe, Mn, Ni, Cu, Zn and Pb. The distribution of their dissolved chemical species in water samples and in the aqueous soil extracts was calculated using a thermodynamic approach. The relationship chemical species - bioaccumulation was discussed.ResultsWaters and soils in the East zone of Maglizh area were found to be more polluted compared to those in the West one, regarding Ni, Mn, Zn, Pb and Cu, while Mn and Cu displayed the highest mobility in West zone soils. Trace metals contents in Ranunculus acris exceed that in Gramineae, since the highest accumulation factors were calculated for Cu and Zn. The highest accumulation in rats was found for Zn followed by Cu, being higher in the West zone. Thermodynamic modelling shows that Mn²⁺ free ions are dominant in both waters and aqueous soil extracts. Ni²⁺ and Zn²⁺ ions followed by metal-organic complexes are dominant in waters of East zone while metal-organic complexes followed by free ions are dominant in waters of West zone and both soil extracts. Metal-organic complexes are dominant for Fe, Cu and Pb in all samples studied, while mainly hydroxy forms (Al(OH)₄⁻) followed by metal-organic complexes are typically for Al depending on pH.ConclusionsExperimentally established bioaccumulation of trace metals in the studied vegetation and rats is a consequence of the total concentration of trace metals in waters and soils, their mobility and chemical species. The dominance of organic complexes of trace metals is a prerequisite for their bioaccumulation in plants. Rats are in direct contact with the soil solution and therefore, of importance is the content of free ions of Mn²⁺, Ni²⁺, Zn²⁺, which are easily absorbed through the skin. The host-helminth system wild rat/H. diminuta could be used as a bioindicator for trace metals pollution.     

Plant metal content, growth responses and some photosynthetic measurements on field-cultivated wheat growing on ore bodies enriched in Cu

Some elemental levels, morphological and photosynthetic characteristics and cellular metabolites of wheat plants (Triticum aestivum L. cv. Vergina) growing in the field on an ore body (Cu concentration in the soil 3050 ug g^?1) were compared to control plants growing in the same environment where the Cu concentration in the soil was 140 μg g¹. The concentrations of Cu, K, Pb, Zn, Mg and Fe were higher in the ore plants but Ca was lower. Growth of the ore plants was inhibited, with decreased height (25%), weight (5%), leaf area (7%) and leaf dry weight (5%) compared to the control plants. Leaf protein concentration of the ore plants was 16. 2 mg cm² leaf area, 63% of that of the control plants. The ore plants were chlorotic and chlorophyll concentration was 3. 8 μg cm^?2 leaf area, 6. 4 times lower than that in the control plants. Ribulose 1. 5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4. 1. 1. 39) activity was 13. 4 μmol CO₂ fixed (mg dry weight)^?1 min^?1, 164% of the activity in control plants. Therefore, growth inhibition did not appear to result from inhibition of the dark reactions of photosynthesis. High Rubisco activity appears to be maintained to permit maximal CO₂ fixation rates whenever energy is available. Parameters of chlorophyll fluorescence F_m, F_v, I_1/2 and F_v/F_m were lower in the ore-grown plants than in control plants; F_m was higher. These values indicate that there is a decrease in the pool size of the electron acceptors on the reducing side of photosystem II (PSII), a destruction of PSII centres and interference in the photochemistry of PSII. The nitrogen content, soluble sugars, starch and lipid content were lower in ore-grown plants. Lower carbohydrate levels appear to result from low photosynthetic activity. The fatty acid composition of lipids was similar in both groups. A lower proportion of polyunsaturated fatty acids was found in the ore-grown plants. Stress caused by high Cu concentration in the soil appears to affect the light reactions of photosynthesis leading to growth inhibition.