Plant uptake of metals,transfer factors and prediction model for two contaminated regions of Kosovo

The bioavailability and plant uptake of heavy metals (HM), as well as finding the most reliable methods for the prediction of availability, continues to be one of the most crucial problems in agricultural and environmental studies. In agricultural soils from two regions in Kosovo, known for its metal pollution, we collected 60 soil and plant samples (wheat, corn, potatoes, and grass). Heavy metals were extracted from soil with aqua regia (pseudototal concentration), NH₄OAc‐EDTA (potential bioavailable), and NH₄NO₃ (mobile fraction), plant samples were digested with HNO₃/H₂O₂ (microwave assisted extraction). The pseudo total content of Cd, Pb, and Zn showed high value in Mitrovice (mean: Cd–2.92, Pb–570.15, and Zn–522.86 mg kg^?1), whereas in Drenas region Ni and Cr showed high value with a mean 258.54 and 203.22 mg kg^?1. Also, the potential bioavailability and mobile form of these metals were increased in Mitrovice (mean: Cd–1.59, Pb–217.05, Zn–522.86 mg kg^?1, respectively Cd–0.17, Pb–0.64, and Zn–15.45 mg kg^?1), compared to Drenas. Cd and Pb were elevated in potato tubers (mean Cd–0.48 and Pb–0.85 mg kg^?1). The TF was higher for micronutrients (Zn and Cu) than for non‐essential metals (Cd and Pb). Multiple regression analysis showed a good model for prediction of Cd, Pb and Zn content in plant with significance 99.9%, whereas this model was not significant for Cu, Cr, and Ni. Soil pH played a significant role in the content of Cd and Zn in wheat and potato plants. Clay content also showed significance in Cd concentration in wheat and potato plants, while carbon content was significant for Cd in grass plants, as well as for Zn in wheat and grass plants.     

Potential of Borago officinalis, Sinapis alba L. and Phacelia boratus for Phytoextraction of Cd and Pb from Soil

Heavy metal phytoextraction is a soil remediation technique, which makes use of plants in removing contamination from soil. The plants must thus be tolerant to heavy metals, adaptable to soil and climate characteristics, and able to take up large amounts of heavy metals. Most of the high biomass productive plants such as, maize, oat and sunflower are plants, which do not grow in cold climates or need intensive care. In this study three “weed” plants, Borago officinalis; Sinapis alba L. and Phacelia boratus were investigated for their ability to tolerate and accumulate high amounts of Cd and Pb. Pot experiments were performed with soil containing Cd and Pb at concentrations of up to 180 mg kg^?1 and 2,400 mg kg^?1 respectively. All three plants showed high levels of tolerance. Borago officinalis; and Sinapis alba L. accumulated 109 mg kg^?1 and 123 mg kg^?1 Cd, respectively at the highest Cd spiked soil concentration. Phacelia boratus reached a Cd concentration of 42 mg kg^?1 at a Cd soil concentration of 100 mg kg^?1. In the case of Pb, B. officinalis and S. alba L. displayed Pb concentrations of 25 mg kg^?1 and 29 mg kg^?1, respectively at the highest Pb spiked soil concentration. Although the Pb uptake in P. boratus reached up to 57 mg kg^?1 at a Pb spiked soil concentration of 1,200 mg kg^?1, it is not suitable for phytoextraction because of its too low biomass.     

Heavy Metal Content in Lettuce Plants Grown in Biosolids Compost

The objective of this work was to evaluate the affects of the application of composted biosolids on the accumulation of heavy metals (Cd, Cu, Ni, Pb and Zn) in lettuce leaves. Pots containing different proportions (0 to 100%) of composted biosolids were used to grow lettuce plants under greenhouse conditions. Dry and fresh weight, leaf area and Cd, Cu, Ni, Pb and Zn uptake were determined after harvest. It was found that the dry and fresh matter productions of the plants were significantly lower in the control treatment. The addition of composted biosolids caused a 20 and 40% increase in biomass accumulation. Cd and Pb concentrations in leaves were below detection limits (0.05 mg kg^?1) in all treatments. Zn concentration in leaves increases as compost proportion decreases, ranging from 57.2 to 80.4 mg kg^?1. Composted biosolids application increased the Cu and Ni plant concentrations, ranging from 5.1 to 9.8 mg Cu kg^?1 and 2.3 to 3.7 mg Ni kg^?1. In all treatments the proportions of heavy metals in plants were below the international standards of toxicity. The results allow us to suggest that, in short-term applications, composted biosolids could be used as soil amendment for lettuce production, without toxic effects in the chemical composition of the plant.     

Chelate-Assisted Phytoextraction of Cadmium and Lead using Mustard and Fenugreek

A screen-house experiment was conducted to study cadmium (Cd) and lead (Pb) phytoextraction using mustard and fenugreek as test crops. Cadmium was applied at a rate of 20 mg kg^?1 soil for both crops, and Pb was applied at 160 and 80 mg kg^?1 soil for mustard and fenugreek, respectively. The disodium salt of ethylenediamine tetraacetic acid (EDTA) was applied at 0, 0.5, 1.0, and 1.5 g kg^?1 soil. Dry-matter yield (DMY) of both crops decreased with increasing rates of EDTA application. Application of 1.5 g EDTA kg^?1 soil caused 23% and 70% declines in DMY of mustard and fenugreek shoots, respectively, in the soils receiving 20 mg Cd kg^?1 soil. Similarly, in soil with 160 mg Pb kg^?1 soil, application of 1.5 g EDTA kg^?1 resulted in 25.4% decrease in DMY of mustard shoot, whereas this decrease was 55.4% in fenugreek grown on a soil that had received 80 mg Pb kg^?1 soil. The EDTA application increased the plant Cd and Pb concentrations as well as shoot/root ratios of these metals in both the crops. Application of 1.5 g kg^?1 EDTA resulted in a 1.50-fold increase in Cd accumulation and a 3-fold increase in Pb accumulation by mustard compared to the control treatment. EDTA application caused mobilization of Cd and Pb from carbonate, manganese oxide, and amorphous iron oxide fractions, which was evident from decrease in these fractions in the presence of EDTA as compared to the control treatment (no EDTA).     

Anthropogenic Heavy Metal Pollution in the Surficial Sediments of the Keratsini Harbor, Saronikos Gulf, Greece

The contents of ten elements [Cd, Pb, W, Zn, Mn, As, Se, Cr, Cu, and organic carbon (C_org)] have been determined in the surficial sediments of Keratsini harbor, Saronikos Gulf, Greece. The contamination of the sediments was assessed on the basis of geoaccumulation index and to corresponding sediment quality guidelines (SQGs) effects range low/effects range median. The results revealed highly elevated Cd, Pb, W, Zn, As, Se, Cr, Cu, and C_org values (Cd, 190–1,763 mg kg^?1; Pb, 521–1,263 mg kg^?1; W, 38–100 mg kg^?1; Zn, 409–6,725 mg kg^?1; Mn, 95–1,101 mg kg^?1; As, not detectable–1,813 mg kg^?1; Se, not detectable–58 mg kg^?1; Cr, 264–860 mg kg^?1; Cu, 195–518 mg kg^?1; and C_org, 0.69–4.41%). The enrichment of metals in the sediments results from the contribution of the central Athens sewage outfall through which the waste of the Attica basin ends up in Keratsini harbor as well as from industrial and ship contaminants.     

Reduction of soil heavy metal bioavailability by nanoparticles and cellulosic wastes improved the biomass of tree seedlings

The purpose of this study was to use zero‐valent iron nanoparticles (nZVI) and cellulosic wastes to reduce bioavailability of lead (Pb) and cadmium (Cd), and to establish Persian maple seedlings (Acer velutinum Bioss.) in contaminated soil. One‐year‐old seedlings were planted in pots filled with unpolluted soil. Lead [Pb(NO₃)₂] and Cd [Cd(NO₃)₂] were added with concentrations of 0 (Control), 100 (Pb100), 200 (Pb200), and 300 (Pb300) mg kg⁻¹ and 10 (Cd10), 20 (Cd20), and 30 (Cd30) mg kg⁻¹. Cellulosic wastes were mixed with soil at the same time of planting [four levels: 0, 10 (W1), 20 (W2), 30 (W3) g 100 g⁻¹ soil]. The nZVI was prepared by reducing Fe³⁺ to Fe⁰ and injected to pots [four levels: 0, 1 (N1), 2 (N2), and 3 (N3) mg kg⁻¹]. Height, diameter, biomass, tolerance index of seedlings, bioavailability of heavy metals in soil, and removal efficiency of amendments were measured. The highest values of seedling characteristics were observed in N3. The highest removal efficiency of Pb (Pb100: 81.95%, Pb200: 75.5%, Pb300: 69.9%) and Cd (Cd10: 92%, Cd20: 73.7%, Cd30: 68.5%) was also observed in N3. The use of nZVI and cellulosic waste could be a proper approach for seedling establishment in forests contaminated with heavy metals.     

Roles of Bacillus megaterium in Remediation of Boron,Lead, and Cadmium from Contaminated Soil

Phytoremediation is an attractive, economical alternative to soil removal and burial methods to remediate contaminated soil. The objective of this study was to investigate the effects of adding different rates of Bacillus megaterium on the capacity of Brassica napus plants to take up boron (B), lead (Pb), and cadmium (Cd) from polluted soils under field conditions. Field experiments were conducted using a randomized complete block design with control (without pollution and B. megaterium application) and B, Pb, and Cd in two doses (0 and 100 mg kg^?1), B. megaterium with four doses (no application and 10⁸ cfu B. megaterium ml^?1 sprayed at 50 ml plot^?1, 100 ml plot^?1, 150 ml plot^?1). Results indicated that soil pollution treatments significantly decreased seed (SDMY), shoot (SHDMY), root (RDMY), and total dry-matter yield (TDMY) of plants at 42.9, 3.8, 62.6, and 23.4% for B-polluted treatment; 25.8, 8.7, 17.6, and 14.2% for Pb-polluted treatment; and 33.2, 7.0, 14.0, and 16.4% for Cd-treatment without B. megaterium application, respectively. However, the application of B. megaterium ameliorated the negative effects of B, Pb, and Cd at 41.4, 52.7, and 10.9% for B; 24.4, 21.6, and 4.9% for Pb; and 22.8, 22.0, and 3.3% for Cd, respectively. The potentially bioavailable and relatively available fraction of soil B, Pb, and Cd increased with increases in the B. megaterium application but total fraction and stable fraction decreased. It is concluded that the seed and shoot parts of B. napus can be used as hyperaccumulators for plant B, Pb, and Cd remediation according to remediation factors but the shoot is the biggest part of the plant, and thus an important portion of the plant to remove B, Pb, and Cd from the B-, Pb-, and Cd-contaminated soils. To decrease desired concentration for 8 mg B kg^?1, 4 mg Pb kg^?1, and 3 mg Cd kg^?1 in the active rooting zone of soil, approximately 2, 6, and 21 years would be necessary with only 150 ml plot^?1 B. megaterium–sprayed soil cultivated with B. napus, respectively.     

Organic and Inorganic Amendments Affect Soil Concentration and Accumulation of Cadmium and Lead in Wheat in Calcareous Alkaline Soils

Irrigation with untreated effluent in periurban agriculture could result in accumulation and bioconcentrations of cadmium (Cd) and lead (Pb). Different amendments were used to investigate their effect on availability, concentration, and uptake of metals by wheat in texturally different soils. Crop was irrigated with water containing Cd and Pb at 20 mg L^?1, thereby adding 260 mg pot^?1 of each metal. Amendments included calcium carbonate at 6 or 12%, gypsum at 50 or 100% of the soil gypsum requirement, farm manure at 7.50 or 15.00 g kg^?1 soil, and a control. Amendments decreased ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA)–extractable Cd and Pb concentrations and uptake by wheat. Dry matter, concentration, uptake, and extractability of Cd and Pb were greater in sandy loam soil compared with those in sandy clay loam soil irrespective of amendments. Sequential extraction showed that more metals were extracted from the control in all fractions and that predominantly metals were found in the carbonate fraction.     

Remediation of a Sandy Soil Contaminated with Cadmium,Nickel, and Zinc using an Insoluble Polyacrylate Polymer

Abstract

This study was carried out to investigate whether an insoluble polyacrylate polymer could be used to remediate a sandy soil contaminated with cadmium (Cd) (30 and 60 mg Cd kg^?1 of soil), nickel (Ni) (50 and 100 mg Ni kg^?1 of soil), zinc (Zn) (250 and 400 mg Zn kg^?1 of soil), or the three elements together (30 mg Cd, 50 mg Ni, and 250 mg Zn kg^?1 of soil). Growth of perennial ryegrass was stimulated in the polymer‐amended soil contaminated with the greatest amounts of Ni or Zn, and when the three metals were present, compared with the unamended soil with the same levels of contamination. Shoots of plants cultivated in the amended soil had concentrations of the metals that were 24–67% of those in plants from the unamended contaminated soil. After ryegrass had been growing for 87 days, the amounts of water‐extractable metals present in the amended soil varied from 8 to 53% of those in the unamended soil. The results are consistent with soil remediation being achieved through removal of the metals from soil solution.     

Chemical characterization of heavy-metal contaminated soil in southeast Kansas

A tri-state mining region, including parts of Missouri, Oklahoma, and Kansas, was the site of intense lead and zinc mining and smelting activity until the 1950's. A study was initiated to characterize the heavy-metal contamination of soils in this area. Water-soluble, an index of plantavailable, total, and sequentially extractable metals; organic, and total carbon; and saturated paste pH were determined for mine tailings and soil samples. Mine tailings contained 81 to 89 mg kg^?1 total Cd, 1 150 to 1 370 mg kg^?1 total Pb, and 11 400 to 13 700 mg kg^?1 total Zn. Total concentrations in soil samples were 15 to 86 mg kg^?1 Cd, 35 to 1 620 mg kg^?1 Pb, and 99 to 18 500 mg kg^?1 Zn; and, DTPA extractable concentrations ranged from 0.6 to 10 mg kg^?1 Cd, 7.8 to 68 mg kg^?1 Pb, and 33 to 715 mg kg^?1 Zn. Samples were sequentially extracted to approximate the proportions of the metals in the sulfide, carbonate, organic, sorbed, and exchangeable fractions. For Zn and Cd, concentrations were greatest in the sulfide fraction followed by carbonate, organic, sorbed, and exchangeable. Lead followed the same pattern, except higher concentrations were observed in the sorbed than the organic fractions.     

Effects of Graded Levels of Cadmium on Spinach and Cabbage Grown in an Inceptisol

Cadmium (Cd) contamination of the soil and its concentrations in spinach and cabbage were studied in a pot culture experiment. Eight levels of Cd (0–100 mg kg^?1 soil) were applied singly. Application of Cd of up to 10 and 15 mg kg^?1 resulted in safe Cd concentrations (1.56 and 1.38 mg kg^?1) in the shoots of spinach and cabbage, respectively, at the consumable stage. The total chlorophyll content gradually decreased with the addition of Cd, and the maximum decreases were 31.7 and 32% in spinach and cabbage, respectively, at 60 days of crop growth in the treatment Cd₁₀₀ over the control. The greatest diethylene triamine penta-acetic acid (DTPA)–extractable Cd contents in the postharvest soil of spinach and cabbage were 22.09 and 24.22 mg kg^?1, respectively, in the treatment Cd₁₀₀. The DTPA Cd was significantly negatively correlated with leaf area and total chlorophyll content while positively correlated with root and shoot Cd concentrations of spinach and cabbage.     

Application of Organic Wastes in a Soil Polluted with Different Rates of Cr-Pb: Effects on Soil Biological Properties

An experiment was performed to determine the effects of adding municipal solid waste (MSW) and poultry manure (PM) to a soil polluted with chromium (Cr), lead (Pb), and Cr + Pb on the biological parameters of the soil. Soil was mixed with two solutions of Cr(NO₃)₃ and/or Pb(NO₃)₂ to give three concentrations (0, 100, and 250 mg Cr kg^?1 soil and 0, 100, and 250 mg Pb kg^?1 soil) and treated with MSW or PM. When the soil was contaminated with the metals without combining, the greatest adenosine triphosphate (ATP), urease, and phosphatase inhibition percentages occurred for 250 mg Pb kg^?1 soil. When the heavy metals were mixed, the inhibition of the biochemical parameters increased. The application of MSW and PM decreased the inhibition of the biochemical parameters and microbial population in the polluted soils. The inhibition percentage was greater for the soil amended with MSW than with PM, possibly due to the high humic acid concentration.     

Heavy Metal Pollution in Soils Around the Abandoned Mine Sites of the Iberian Pyrite Belt (Southwest Spain)

This paper investigates the pollution load of selected trace elements in 32 soil samples collected around 21 different mining areas of the Iberian Pyrite Belt (Southwest Spain), integrating chemical data with soil parameters to help understand the partitioning and mobility of pollutants. The minesoils are depleted in acid neutralising minerals and show limiting physicochemical properties, including low pH values and very high anomalies of potentially hazardous metals. The total concentrations of As (up to 1,560 mg kg^?1) and certain heavy metals (up to 2,874 mg kg^?1 Cu, 6,500 mg kg^?1 Pb, 6,890 mg kg^?1 Zn, 62 mg kg^?1 Hg and 22 mg kg^?1 Cd) are two orders of magnitude above the soil background values. The close association of Cd and Zn with the carbonate content in lime-amended minesoils suggests metal immobilisation through adsorption and/or co-precipitation mechanisms, after acid neutralisation, whereas As and Pb are similarly partitioned into the soil and mostly associated with iron oxy-hydroxides.     

Functional and Structural Changes associated with Cadmium in Mustard Plant: Effect of Applied Sulphur

Abstract

The effect of cadmium (Cd) and sulphur (S) on dry weight, biochemical parameters and anatomical features of mustard (Brassica campestris L. cv. Pusa Bold) plant was investigated in a pot culture experiment using Cd (25, 50, and 100 mg kg^?1 of soil), S (40 mg kg^?1 of soil), and the combination of Cd+S (25+40 mg kg^?1 of soil, 50+40 mg kg^?1 of soil, and 100+40 mg kg^?1 of soil). Sulphur treatment was given at sowing and Cd treatment was given when seedlings were fully established. Observations were recorded at the flowering stage. A significant and antagonistic interaction of Cd and S was observed. Compared to the control, leaf dry weight, total chlorophyll content, sugar content, nitrate reductase activity, and protein content decreased significantly with each Cd treatment, whereas the reverse was observed with S treatment. Combined treatments of Cd+S also reduced these parameters, but this reduction was less than the one observed with Cd treatments alone. However, nitrate accumulation in the leaves was 2.35 times higher with treatment of 100 mg Cd+40 mg S kg^?1 of soil than in the controls, whereas it was 3.5 times higher with Cd (100 mg kg^?1 of soil) alone. The relative proportion of vasculature in the stem, stoma length and width, and stomata length and width were inhibited with Cd treatments, whereas the combined treatments mitigated the adverse effect caused by Cd. Thus, S could alleviate the Cd induced impairment of biochemical and anatomical features of the plant and the enhancement of nitrate accumulation in the leaves.     

Water extractable concentrations of Fe,Mn, Ni,Co, Mo,Pb and Cd under different land uses of Danube basin in Croatia

Abstract

Water extraction of trace elements can simulate the concentration of elements in the soil solution from where the plant takes up the elements. The objective of this investigation was to determine the water extractable concentration of seven trace elements (Fe, Mn, Ni, Co, Mo, Pb and Cd) and to assess their relationship with soil properties of the Danube basin in Croatia. Soil samples from the surface layer (0–25 cm) of 74 sites, having different land uses (forest and agricultural land), were collected. Samples were analysed for total and water extractable trace elements as well as for pH, DOC, SOC and CEC. The concentrations of water extractable fraction of trace elements were on average: 20.14 mg kg^?1 for Fe, 3.61 mg kg^?1 for Mn, 0.07 mg kg^?1 for Ni, 0.016 mg kg^?1 for Co, 0.01 mg kg^?1 for Mo, 0.01 mg kg^?1 for Pb and 0.0009 mg kg^?1 for Cd. Soil properties were in the following range: pH 4.3–8 (Avg: 6.35), DOC 6.1–73 mg l^?1 (Avg: 26 mg l^?1), CEC 1.3–24 cmol kg^?1 (Avg: 9 cmol kg^?1) and SOC 0.5–5% (Avg: 1.7%). The concentration of water extractable fraction of trace elements was significantly correlated with pH (p <0.001), DOC (p <0.001 – p <0.05) and CEC (p <0.001) but their relationship with total content of trace element and SOC was rather weak, suggesting that total metal alone cannot be an indicator of toxicity or deficiency. Results show that pH, DOC and CEC are important soil quality parameters taking part in the solubility control of trace metals in the soil rather than their total concentration. The difference between land uses has been observed as well, suggesting that a change in land use can cause a change in trace element solubility.     

Heavy metal pollution by long range atmospheric transport in natural soils of Southern Norway

Natural surface soils in Southern Norway are strongly contaminated by metals from atmospheric deposition. Except from local pollution with Cu, Ni and to a limited extent Pb around the town of Kristiansand, this large-scale contamination can be ascribed to long-range atmospheric transport from other parts of Europe. Zinc, As, Cu, and Pb are all found in excessive concentrations in the surface layer of natural soils throughout the region, and in particular within a zone of about 20 to 40 km from the coast. In this zone the elements appear at the following concentrations or higher in the A₀ layer (typical levels in other parts of Norway little affected by air pollution in parantheses): Zn, 120(30) mg kg^?1; As, 4(0.5) mg kg^?1; Cd, 2(0.2) mg kg^?1; Pb, 160(15) mg kg^?1. Possible harmful effects to soil biological processes of this contamination cannot be excluded.     

Heavy‐Metal Inhibition of Nitrification in Selected Iowa Soils Treated with Stay‐N 2000

Abstract

Heavy‐metal inhibition of nitrification in soils treated with reformulated nitrapyrin was investigated. Clarion and Okoboji soils were treated with ammonium sulfate [(NH₄)₂SO₄] and a nitrification inhibitor. Copper(II) (Cu), Zinc(II) (Zn), Cadmium(II) (Cd), or Lead(II) (Pb) were added to each soil. A first‐order equation was used to calculate the maximum nitrification rate (K _max), duration of lag period (t′), period of maximum nitrification (Δt), and the termination period of nitrification (t _s). In the Clarion soil, the K _max decreased from 12 mg kg^?1 d^?1 without the nitrification inhibitor to 4, 0.25, 0.86, and 0.27 mg kg^?1 d^?1, respectively, when the inhibitor and Cu, Zn, Pb, or Cd were applied. In the Okoboji soil, K _max decreased from 22 mg kg^?1 d^?1 with no inhibitor to 6, 3, 4, and 2 mg kg^?1 d^?1, respectively, when an inhibitor and Cu, Zn, Pb, or Cd were added. The t′ varied from 8 to 25 d in the Clarion soil and from 5 to 25 d in the Okoboji soil, due to addition of Cu, Zn, Pb, or Cd and the inhibitor.     

Relationship Between Extractable Metals in Acid Soils and Metals Taken Up by Tea Plants

Abstract

The accumulation of heavy metals in plants is related to concentrations andchemical fractions of the metals in soils. Understanding chemical fractions and availabilities of the metals in soils is necessary for management of the soils. In this study, the concentrations of copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn) in tea leaves were compared with the total and extractable contents of these heavy metals in 32 surface soil samples collected from different tea plantations in Zhejiang province, China. The five chemical fractions (exchangeable, carbonate‐bound, organic matter‐bound, oxides‐bound, and residual forms) of the metals in the soils were characterized. Five different extraction methods were also used to extract soil labile metals. Total heavy metal contents of the soils ranged from 17.0 to 84.0 mgCukg^?1, 0.03 to 1.09 mg Cd kg^?1, 3.43 to 31.2 mg Pb kg^?1, and 31.0 to 132.0 mg Zn kg^?1. The concentrations of exchangeable and carbonate‐bound fractions of the metals depended mainly on the pH, and those of organic matter‐bound, oxides‐bound, and residual forms of the metals were clearly controlled by their total concentrations in the soils. Extractable fractions may be preferable to total metal content as a predictor of bioconcentrations of the metals in both old and mature tea leaves. The metals in the tea leaves appeared to be mostly from the exchangeable fractions. The amount of available metals extracted by 0.01 mol L^?1 CaCl₂, NH₄OAc, and DTPA‐TEA is appropriate extractants for the prediction of metals uptake into tea plants. The results indicate that long‐term plantation of tea can cause sol acidification and elevated concentrations of bioavailable heavy metals in the soil and, hence, aggravate the risk of heavy metals to tea plants.     

Cd, Ni, Pb, and Zn Concentrations in Forest Vegetation and Soils in Maine

Bioaccumulation of trace metals in plant tissues can present a health risk to wildlife, and potentially to humans. The Passamaquoddy tribe in Maine was concerned about health risks of cadmium (Cd) because of a health advisory for moose liver and kidney consumption due to high Cd levels. This study found relatively low to moderate concentrations of Cd, nickel (Ni), lead (Pb), and zinc (Zn) concentrations in four common terrestrial moose browse species, associated forest soils, and two species of aquatic vegetation on Passamaquoddy tribal land in eastern Maine. Terrestrial plant tissue concentrations ranged from 0.1 to 1.97, 0.65 to 7.08, 0.29 to 2.0, and 42 to 431 mg kg^?1 for Cd, Ni, Pb and Zn, respectively. Deciduous species, particularly aspen and birch, may be a more significant source of Cd and Zn to wildlife compared to coniferous or aquatic species. Aquatic plant tissue concentrations ranged from 0.11 to 0.14, 0.46 to 1.01, 0.8 to 0.9, and 22 to 41 mg kg^?1 for Cd, Ni, Pb and Zn, respectively. Total O horizon concentration means for coniferous and deciduous were 0.50 and 1.00, 4.27 and 4.11, 55 and 21, and 55 and 167 mg kg^?1 for Cd, Ni, Pb and Zn, respectively. The study provides baseline vegetation and soil trace metal concentrations for a remote region in Maine impacted by non-point sources.     

Trace Element Concentrations in Saltmarsh Soils Strongly Affected by Wastes from Metal Sulphide Mining Areas

Soil and water samples were analysed for trace metals and As in two watercourses and 14 sampling plots in a salt marsh polluted by mine wastes in SE Spain. Groundwater levels, soil pH and Eh were measured ‘in situ’ for a 12-month period in each sampling plot, and total calcium carbonate was also determined. Low concentrations of soluble metals (maximum Mn 1.089 mg L^?1 and maximum Zn 0.553 mg L^?1) were found in the watercourses. However, total metal contents were extremely high in the soils of a zone of the salt marsh (maximum 1,933 mg kg^?1 of Mn, 62,280 mg kg^?1 of Zn, 16,845 mg kg^?1 of Pb, 77 mg kg^?1 of Cd, 418 mg kg^?1 of Cu and 725 mg kg^?1 of As), and soluble metals in the pore water reached 38.7 mg L^?1 for Zn, 3.15 mg L^?1 for Pb, 48.0 mg L^?1 for Mn, 0.61 mg L^?1 for Cd and 0.29 mg L^?1 for As. Variable concentrations with depth indicate a possible re-mobilisation of the metals, which could be related to spatial and temporal variations of water table level, pH and Eh and to the presence of calcium carbonate. A tendency for the Eh to decrease in the warmest months and to increase in the coldest ones was found, especially, in plots that received water with a high content of dissolved organic carbon. Hence, the existence of nutrient effluent-enriched water may modify the physical–chemical conditions of the soil–water system and influence metal mobility.