Heavy Metal Contamination of Arable Soil and Corn Plant in the Vicinity of a Zinc Smelting Factory and Stabilization by Liming

The heavy metal contamination in soils and cultivated corn plants affected by zinc smelting activities in the vicinity of a zinc smelting factory in Korea was studied. Soils and corn plants were sampled at the harvesting stage and analyzed for cadmium (Cd) and zinc (Zn) concentration, as well as Cd and Zn fraction and other chemical properties of soils. Cd and Zn were highly accumulated in the surface soils (0–20 cm), at levels higher than the Korean warning criteria (Cd, 1.5; Zn, 300 mg kg⁻¹), with corresponding mean values of 1.7 and 407 mg kg⁻¹, respectively, but these metals decreased significantly with increasing soil depth and distance from the factory, implying that contaminants may come from the factory through aerosol dynamics (Hong et al., Kor J Environ Agr 26(3):204–209, 2007a; Environ Contam Toxicol 52:496–502, 2007b) and not from geological sources. The leaf part had higher Cd and Zn concentrations, with values of 9.5 and 1733 mg kg⁻¹, compared to the stem (1.6 and 547 mg kg⁻¹) and grain (0.18 and 61 mg kg⁻¹) parts, respectively. Cd and Zn were higher in the oxidizable fraction, at 38.5% and 46.9% of the total Cd (2.6 mg kg⁻¹) and Zn (407 mg kg⁻¹), but the exchangeable + acidic fraction of Cd and Zn as the bioavailable phases was low, 0.2 and 50 mg kg⁻¹, respectively. To study the reduction of plant Cd and Zn uptake by liming, radish (Raphanus sativa L.) was cultivated in one representative field among the sites investigated, and Ca(OH)₂ was applied at rates of 0, 2, 4, and 8 mg ha⁻¹. Plant Cd and Zn concentrations and NH₄OAc extractable Cd and Zn concentrations of soil decreased significantly with increasing Ca(OH)₂ rate, since it markedly increases the cation exchange capacity of soil induced by increased pH. As a result, liming in this kind of soil could be an effective countermeasure in reducing the phytoextractability of Cd and Zn.     

Effect of Long-Term Zinc Pollution on Soil Microbial Community Resistance to Repeated Contamination

The aim of the study was to compare the effects of stress (contamination trials) on the microorganisms in zinc-polluted soil (5,018 mg Zn kg⁻¹ soil dry weight) and unpolluted soil (141 mg Zn kg⁻¹ soil dw), measured as soil respiration rate. In the laboratory, soils were subjected to copper contamination (0, 500, 1,500 and 4,500 mg kg⁻¹ soil dw), and then a bactericide (oxytetracycline) combined with a fungicide (captan) along with glucose (10 mg g⁻¹ soil dw each) were added. There was a highly significant effect of soil type, copper treatment and oxytetracycline/captan treatment. The initial respiration rate of chronically zinc-polluted soil was higher than that of unpolluted soil, but in the copper treatment it showed a greater decline. Microorganisms in copper-treated soil were more susceptible to oxytetracycline/captan contamination. After the successive soil contamination trials the decline of soil respiration was greater in zinc-polluted soil than in unpolluted soil.     

Soil-Based Phytotoxicity of 2,4,6-Trinitrotoluene (TNT) to Terrestrial Higher Plants

Seed germination and early stage seedling growth tests were conducted to determine the ecotoxicological threshold of 2,4,6-trinitrotoluene (TNT) in two soils of different properties. Soils were amended up to 1,600 mg TNT kg⁻¹ soil and four representative species of higher plants, two dicotyledons (Lepidium sativum L., common name: cress; and Brassica rapa Metzg., turnip) and two monocotyledons (Acena sativa L., oat; and Triticum aestivum L., wheat), were assessed. Cumulative seed germination and fresh shoot biomass were measured as evaluation endpoints. Phytotoxicity of TNT was observed to be affected by soil properties and varied between plant species. Cress and turnip showed higher sensitivity to TNT than did oat and wheat. The lowest observable adverse effect concentration (LOAEC) of TNT derived from this study was 50 mg kg⁻¹ soil. In contrast to high TNT concentrations, low levels of TNT, i.e., 5–25 mg kg⁻¹ soil for cress and turnip and 25–50 mg kg⁻¹ for oat and wheat, stimulated seedling growth. Oat was capable of tolerating as much as 1,600 mg TNT kg⁻¹ and demonstrated a potential ability of TNT detoxification in one of the soils tested, suggesting that this plant might be useful in the bioremediation of TNT contaminated soils. Received: 15 May 1998/Accepted: 30 September 1998     

Effect of Metal-Tolerant Plant Growth-Promoting <Emphasis Type="Italic">Rhizobium</Emphasis> on the Performance of Pea Grown in Metal-Amended Soil

The nickel- and zinc-tolerant plant growth-promoting (PGP) Rhizobium sp. RP5 was isolated from nodules of pea, grown in metal-contaminated Indian soils. The PGP potentials of strain RP5 was assessed under in vitro conditions. Strain RP5 displayed a high level of tolerance to nickel (350 μg ml⁻¹) and zinc (1500 μg ml⁻¹) and showed PGP activity under in vitro conditions. The PGP activity of this strain was further assessed with increasing concentrations of nickel and zinc, using pea as a test crop. The bio-inoculant enhanced the dry matter, nodule numbers, root N, shoot N, leghemoglobin, seed yield, and grain protein (GP) by 19%, 23%, 26%, 47%, 112%, 26%, and 8%, respectively, at 290 mg Ni kg⁻¹ while at 4890 mg Zn kg⁻¹ soil, it increased the dry matter, nodule numbers, leghemoglobin, seed yield, GP, and root and shoot N by 18%, 23%, 78%, 26%, 7%, 25%, and 42%, respectively, compared to plants grown in soil amended with metal only. The bio-inoculant increased the glutathione reductase activity of roots and nodules by 46% and 65% at 580 mg Ni kg⁻¹ and 47% and 54% at 9780 mg Zn kg⁻¹ soil, respectively, compared to uninoculated plants. The inoculated strain decreased the concentration of nickel and zinc in plant organs. The intrinsic abilities of nitrogen fixation, growth promotion, and the ability to reduce the toxicity of nickel and zinc of the tested strain could be of practical importance in augmenting the growth and yield of pea, in nickel- and zinc-polluted soils.     

Residue Dynamic of Pyrimorph on Tomatoes,Cucumbers and Soil under Greenhouse Trails

A modified QuEChERS method for analysis of pyrimorph residue in tomatoes, cucumbers and soil was developed and validated. Residue dynamics and final residues in greenhouse vegetables and soil were studied. At fortification levels of 0.05, 0.1 and 1 mg kg⁻¹ in tomatoes, cucumbers and soil, the method got recoveries ranged from 86.1% to 99.3% with relative standard deviations of 1.0%–7.7%, in agreement with directives for method validation in residue analysis. The limit of determination in tomatoes, cucumbers and soil was 0.05 mg kg⁻¹. The proposed method was successfully employed for the determination of pyrimorph residue levels and dissipation rates in vegetables and soil. At six experimental sites, pyrimorph residues in tomatoes and cucumbers showed relatively fast dissipation rates, with half-lives of 5.8–7.7 days and 5.7–7.1 days respectively. Half-lives of pyrimorph in soil were 8.5–11.0 days. The final residues of pyrimorph in tomatoes ranged from 0.19 to 3.66 mg kg⁻¹, 0.18 to 4.35 mg kg⁻¹ in cucumbers and 0.22 to 16.5 mg kg⁻¹ in soil with pre-harvest interval of 3–7 days. 5 mg kg⁻¹ was proposed as the MRL of pyrimorph in tomatoes and cucumbers.     

Dissipation of Diethyl Aminoethyl Hexanoate (DA-6) Residues in Pakchoi,Cotton Crops and Soil

QuEChERS procedure and acetonitrile extraction, oscillation and ultrasonic procedure followed by GC–MS and LC–MS/MS (QqQ) detections were established for determination of diethyl aminoethyl hexanoate (DA-6) residues in pakchoi, cotton leaf, cotton seed and soil. At concentration levels of 0.005–1 mg kg⁻¹, recoveries were in the range of 80.5%–103.3%, with a RSD less than 14.2%. The LOQs of methods were 0.005, 0.003, 0.005 and 0.001 mg kg⁻¹ for the pakchoi, cotton leaf, soil and cotton seed samples, respectively. DA-6 was applied in supervised field trials at GAP conditions to pakchoi and cotton. It was found that the dissipation half-lives of DA-6 were 5.4–8.2 days and 1.1–2.2 days and 1.5–1.9 days in cotton crop, pakchoi and soil respectively. At harvest, no detectable residues (<LOD) were found in cotton samples. However, residues was detected in pakchoi (0.007–0.013 mg/kg) in Beijing and soil (0.008–0.014 mg/kg) in Changsha in 2008.     

Influence of Petroleum Hydrocarbon Contamination on Microalgae and Microbial Activities in a Long-Term Contaminated Soil

Petroleum hydrocarbons are widespread environmental pollutants. Although biodegradation of petroleum hydrocarbons has been the subject of numerous investigations, information on their toxicity to microorganisms in soil is limited, with virtually no work conducted on soil algae. We carried out a screening experiment for total petroleum hydrocarbons (TPH) and their toxicity to soil algal populations, microbial biomass, and soil enzymes (dehydrogenase and urease) in a long-term TPH-polluted site with reference to an adjacent unpolluted site. Microbial biomass, soil enzyme activity, and microalgae declined in medium to high-level (5,200–21,430 mg kg⁻¹ soil) TPH-polluted soils, whereas low-level (<2,120 mg kg⁻¹ soil) pollution stimulated the algal populations and showed no effect on microbial biomass and enzymes. However, inhibition of all the tested parameters was more severe in soil considered to have medium-level pollution than in soils that were highly polluted. This result could not be explained by chemical analysis alone. Of particular interest was an observed shift in the species composition of algae in polluted soils with elimination of sensitive species in the medium to high polluted soils. Also, an algal growth inhibition test carried out using aqueous eluates prepared from polluted soils supported these results. Given the sensitivity of algae to synthetic pollutants, alteration in the algal species composition can serve as a useful bioindicator of pollution. The results of this experiment suggest that chemical analysis alone is not adequate for toxicological estimations and should be used in conjunction with bioassays. Furthermore, changes in species composition of algae proved to be more sensitive than microbial biomass and soil enzyme activity measurements. Received: 8 April 1999/Accepted: 2 November 1999     

Ecotoxicity of Aged Uranium in Soil Using Plant,Earthworm and Microarthropod Toxicity Tests

Discrepancies about probable no effect concentrations (PNEC) for uranium in soils may be because toxicity tests used freshly contaminated soils. This study used 3 soils amended with a range of uranium concentrations 10 years previously. The toxicity tests with northern wheatgrass (Elymus lanceolatus); earthworm (Eisenia andrei) were not affected below ~1,000 mg U kg⁻¹, and the soil arthropod Folsomia candida was not affected below ~350 mg U kg⁻¹. Survival of Orthonychiurus folsomi was diminished 20% (EC₂₀) by ~85–130 mg U kg⁻¹, supporting a PNEC in the range of 100–250 mg U kg⁻¹ as derived previously.     

Removal and biodegradation of polycyclic aromatic hydrocarbons by Selenastrum capricornutum

The removal and degradation of a mixture of polycyclic aromatic hydrocarbons (PAHs), namely phenanthrene (PHE), fluoranthene (FLA), and pyrene (PYR), by a green microalgal species, Selenastrum capricornutum, at different initial cell densities were studied. The PAH removal efficiency increased with the initial cell density, and 96% of PHE, 100% of FLA, and 100% of PYR in the medium were removed by live S. capricornutum at the density of 1 x 10(7) cells/ml in 4 d, whereas less than 50% of PAHs were removed at the lowest cell density (5 x 10(4) cells/ml) in 7 d. The removal mechanisms included initial adsorption onto the cell walls of both live and dead cells, and the adsorbed PAHs were then absorbed and degraded in live cells only. Among different PAHs in a mixture, irrespective of whether they were added to medium at the same or different concentrations, the removal preference by live S. capricornutum was in the descending order of PYR > FLA > PHE, whereas the biodegradation rates followed the descending order of FLA > PYR > PHE. Initial findings regarding PAH metabolites revealed that PHE was converted into four different monohydroxyphenanthrenes and two dihydroxyphenanthrenes, whereas FLA and PYR were converted into three hydroxylated derivatives through the monooxygenase pathway. The presence of dihydroxylated PAHs suggested that the dioxygenase pathway also might have taken place at the same time.     

Bioavailability and Trophic Transfer of Sediment-Bound Ni and U in a Southeastern Wetland System

Elemental composition of soil, herbaceous and woody plant species, and the muscle and liver tissue of two common small mammal species were determined in a wetland ecosystem contaminated with Ni and U from nuclear target processing activities at the Savannah River Site, Aiken, SC. Species studied were black willow (Salix nigra L.), rushes (Juncus effusus L.), marsh rice rat (Oryzomys palustris), and cotton rat (Sigmodon hispidus). Two mature trees were sampled around the perimeter of the former de facto settling basin, and transect lines sampling rushes and trapping small mammals were laid across the wetland area, close to a wooden spillway that previously enclosed the pond. Ni and U concentrations were elevated to contaminant levels; with a total concentration of 1,065 (± 54) mg kg⁻¹ U and 526.7 (±18.3) mg kg⁻¹ Ni within the soil. Transfer of contaminants into woody and herbaceous plant tissues was higher for Ni than for U, which appeared to remain bound to the outside of root tissues, with very little (0.03 ± 0.001 mg kg⁻¹) U detectable within the leaf tissues. This indicated a lower bioavailability of U than the cocontaminant Ni. Trees sampled from the drier margins of the pond area contained more Ni within their leaf tissues than the rushes sampled from the wetter floodplain area, with leaf tissues concentrations of Ni of approximately 75.5 (± 3.6) mg kg⁻¹ Ni. Ni concentrations were also elevated in small mammal tissues. Transfer factors of contaminants indicated that U bioavailability is negligable in this wetland ecosystem. Received:18 October 2001/Accepted:12 June 2002     

Arsenic Bioaccessibility in a Soil Amended with Drinking-Water Treatment Residuals in the Presence of Phosphorus Fertilizer

A laboratory incubation study was conducted to determine the effect of drinking-water treatment residuals (WTRs) on arsenic (As) bioaccessibility and phytoavailability in a poorly As-sorbing soil contaminated with arsenical pesticides and fertilized with triple super phosphate (TSP). The Immokalee soil (a sandy spodosol with minimal As-retention capacity) was amended with 2 WTRs (Al and Fe) at 5 application rates ranging between 0% and 5% wt/wt. Sodium arsenate and TSP were used to spike the soil with 90 mg As kg⁻¹ and 115 mg P kg⁻¹, respectively. Bioaccessible As was determined at time 0 (immediately after spiking), and at 6 and 12 months of equilibration using an in vitro gastrointestinal test, and As phytoavailability was measured with a 1-M KC1 extraction test. Arsenic phytoavailability decreased immediately after spiking (20% availability at 5% rate), but only after 6 months for the Al-WTR– and the Fe-WTR–amended soil, respectively. Arsenic bioaccessibility simulated for the stomach and intestine phases showed that the Fe-WTR was more effective than the Al-WTR in resisting the harsh acidic conditions of the human stomach, thus preventing As release. Both the phytoavailable As and the bioaccessible As were significantly correlated (p < 0.001) for soil spiked with either Al- or Fe-WTR. Both WTRs were able to decrease soil As bioaccessibility irrespective of the presence or absence of P, which was added as TSP. Results indicate the potential of WTRs in immobilizing As in contaminated soils fertilized with P, thereby minimizing soil As bioaccessibility and phytoavailability.     

Bioavailability of Lead and Cadmium in Soils Artificially Contaminated with Smelter Fly Ash

This study evaluated lead and cadmium uptake by maize grown on soils artificially spiked with smelter fly ash and possible changes in chemical fractionation of these metals in the soil. Maize grown on the less contaminated soil (1,466 mg Pb kg⁻¹; 19 mg Cd kg⁻¹) did not exhibit any chlorosis/necrosis symptoms or lower biomass yields compared to the control. The addition of the chelating agent ethylenediaminetetraacetic acid increased lead uptake by maize, as expected. Neither maize cultivation nor the addition of the chelant influenced significantly the chemical fractionation of lead and cadmium in the soil during the experiment.     

Sources of Arsenic and Fluoride in Highly Contaminated Soils Causing Groundwater Contamination in Punjab,Pakistan

Highly contaminated groundwater, with arsenic (As) and fluoride (F⁻) concentrations of up to 2.4 and 22.8 mg/L, respectively, has been traced to anthropogenic inputs to the soil. In the present study, samples collected from the soil surface and sediments from the most heavily polluted area of Punjab were analyzed to determine the F⁻ and As distribution in the soil. The surface soils mainly comprise permeable aeolian sediment on a Pleistocene terrace and layers of sand and silt on an alluvial flood plain. Although the alluvial sediments contain low levels of F, the terrace soils contain high concentrations of soluble F⁻ (maximum, 16 mg/kg; mean, 4 mg/kg; pH > 8.0). Three anthropogenic sources were identified as fertilizers, combusted coal, and industrial waste, with phosphate fertilizer being the most significance source of F⁻ accumulated in the soil. The mean concentration of As in the surface soil samples was 10.2 mg/kg, with the highest concentration being 35 mg/kg. The presence of high levels of As in the surface soil implies the contribution of air pollutants derived from coal combustion and the use of fertilizers. Intensive mineral weathering under oxidizing conditions produces highly alkaline water that dissolves the F⁻ and As adsorbed on the soil, thus releasing it into the local groundwater.     

“Metals in Fresh Honeys from Tenerife Island, Spain”

Ashes and contents of Zn, Cu, Fe, Cd and Pb in 140 fresh honey samples from three different areas of Tenerife Island were determined by inductively coupled plasma atomic emission spectrometry and graphite furnace atomic absorption spectrometry. A mean ash content of 0.35% has been determined. The mean Fe, Cu, Zn, Pb and Cd concentrations observed have been 3.37 mg kg⁻¹, 1.28 mg kg⁻¹, 2.83 mg kg⁻¹, 37.33 μg kg⁻¹, 4.38 μg kg⁻¹, respectively. A direct statistical correlation has been found between the Fe–Zn and Fe–Pb content, and between the Cd–Zn and Cd–Pb levels.     

Trace Element Concentration in Groundwater,Tuticorin City,Tamil Nadu,India

The aim of the present study is to investigate the pollution vulnerability of groundwater aquifers in the coastal regions of Tuticorin city, Tamil Nadu, India. Fourteen samples were analyzed to determine the concentration of trace elements (Pb, Zn, Cd, Hg, Cr and Cu) in the groundwater. Among the total samples six were collected from industrial areas and eight from non-industrial areas of Tuticorin city. The concentration of trace element ranges from 0.01 to 0.19 mg/kg⁻¹ for Pb, from 0.01 to 0.16 mg/kg⁻¹ for Zn, from BDL to 0.21 mg/kg⁻¹ for Cd, from BDL (Below Detection Limit) to 0.023 mg/kg⁻¹ for Hg, from 0.02 to 0.18 mg/kg⁻¹ for Cr and from 0.01 to 0.16 mg/kg⁻¹ for Cu. The trace element concentration in groundwater is higher than the WHO suggested maximum permissible limit except Zn and Cu.     

Study of Imidaclothiz Residues in Cabbage and Soil by HPLC with UV Detection

The HPLC method for determination of imidaclothiz residue in cabbage and soil was developed, and its degradation and final residue were studied. The mean accuracies of the analytical method were 92.0–93.0% in soil and 88–93% in cabbage. The precision in cabbage ranged from 2.2% to 5.6%, and in soil from 2.0% to 5.0%. The minimum detectable amount of imidacothiz was 1 × 10⁻¹⁰g. The minimum detectable concentration was 0.0075 mg kg⁻¹ in cabbage and 0.003 mg kg⁻¹ in soil. The results showed that imidaclothiz degradation in soil and cabbage coincided with C = 0.0427e^−0.0923t, C = 0.739e^−0.279t. The half-lives were about 3.1 days in soil and 2.2 days in cabbage.     

Residues and Dissipation Dynamics of Fosthiazate in Tomato and Soil

Residue dynamics of fosthiazate in tomato and soil was studied in this paper utilizing liquid chromatography with tandem mass spectrometry (LC–MS/MS). The field trial was conducted in three sites: Beijing, Liaoning, Hubei in China. Fosthiazate dissipated with the half-life 0.75–2.6 days in tomato or tomato plants and 2.5–11.6 days in soil. In the terminal residue experiment, no higher residue than 0.023 mg kg⁻¹ in tomato and 0.27 mg kg⁻¹ in soil was detected. Residues of fosthiazte in tomato were far below Japan maximum residue levels (0.2 mg kg⁻¹).     

Development and Validation of an Analytical Method to Determine Fipronil and its Degradation Products in Soil Samples

The aim of this study was to develop a methodology for identifying and quantifying Fipronil and its degradation products in soil by gas chromatography–electron capture detector previously extracted using a focused ultrasound probe. This methodology was obtaining a range of recovery between 85 % and 120 %, decreasing approximately solvent used time and cost, respect to other methodologies such as bath ultrasonic, solid-phase extraction, liquid–liquid extraction and soxhlet. The method was validated in fortified matrix, presented linearity in the range of 25–400 μg kg⁻¹, and limit of detection for Fipronil and their products desulfinyl, sulfide and sulfone was 14.7, 9.8, 8.9 and 10.7 μg kg⁻¹, respectively. This process was applied to samples of agricultural soils, where two degradation products desulfinyl and sulfone were found.     

Biodegradation of Fipronil by Paracoccus sp. in Different Types of Soil

In the present studies potential of microorganisms isolated from the cotton fields was explored for the bioremediation of fipronil contaminated soils. The cultures of microbes were grown in Luria broth as shake culture maintained at 28°C. After that Dorn’s broth enrichment culture supplemented with fipronil was used and isolated two bacterial cultures viz. Paracoccus sp. and Gamma Proteobacteria. The performance of both bacteria was evaluated for degradation of fipronil in soil. Paracoccus sp. was found better than the Gamma Proteobacteria as far as degradation of fipronil in soil is concerned. The samples of soil were extracted and cleaned up by following a standardized methodology. Fipronil was quantified by gas liquid chromatography and confirmed by gas chromatography mass spectrometer. The limit of quantification of fipronil was worked out to be 10 μg kg⁻¹. By using this methodology, the mean recoveries of fipronil in different types of soil were found to be more than 85%. The residues of fipronil were found to persist only up to 10 days in soils fortified with fipronil @ 20 μg kg⁻¹ and amended with Paracoccus sp. while in the soils fortified @ 80 μg kg⁻¹ fipronil, residues persisted up to 20, 30 and 30 days in loamy sand, sandy loam and clay loam, respectively. Therefore, the use of Paracoccus sp. can further be explored for the bioremediation of fipronil contaminated soils.     

Lead/Cadmium Contamination and Lead Isotopic Ratios in Vegetables Grown in Peri-Urban and Mining/Smelting Contaminated Sites in Nanjing,China

Lead/cadmium contamination in vegetables grown in peri-urban area of Nanjing, China was assessed and the route for metals entering into plants was investigated through lead isotopic tracing. Results show that agricultural soils have been polluted with Cd. Contents of Pb (22.1–37.5 mg kg⁻¹ dw) and Cd (2.53–4.19 mg kg⁻¹ dw) in vegetables’ edible parts nearby a lead/zinc mining/smelting plant were beyond their maximum allowable limit prescribed in the (EC) No 1881/2006. Pb isotope ratios in plants differed from those in the corresponding soils, suggesting that soils were not the only contamination source of Pb and Cd in plants.