Horizontal and Vertical Distribution of Lead,Cadmium, and Zinc in Farmlands Around a Lead-Contaminated Goldmine in Zamfara,Northern Nigeria

This study was undertaken to evaluate the vertical and horizontal distribution of lead (Pb), cadmium (Cd), and zinc (Zn) in farmlands around a Pb-contaminated goldmine. Total concentrations of Pb and Cd recorded were at maximum values of 2,246.55 and 68.7 mg kg^?1, respectively; these are greater than the threshold values for Pb (300 mg kg^?1) and Cd (3 mg kg^?1). However, the concentration of Zn was within acceptable limits (300 mg kg^?1). Down the soil profile, concentrations of Pb, Cd, and Zn showed two peaks; these were attributed to facilitated transport and ground-water enrichment. Incubation of the soil samples with glucose indicated low microbial process(es), which could be due to the increased levels of Pb and Cd. Factor analysis showed a close association of Pb and Cd with the soil-exchange complex with a possibility of these heavy metals replacing Ca and other divalent cations in the soil-exchange site. This will, however, increase the risk of Pb and Cd leaching and uptake by plants. Although the metals were more associated with resistant soil fraction (sand), which also indicates their geogenic origin, chemical weathering under the influence of pH could release these metals into the soil-exchange site.     

Accumulation and Distribution Characteristics of Zinc and Cadmium in the Hyperaccumulator Plant Sedum plumbizincicola

Accumulation and distribution of Zn and Cd in the hyperaccumulator plant Sedum plumbizincicola were investigated in a hydroponic experiment. Mean Cd and Zn concentrations in shoots (7,010 and 18,400 mg kg^?1) were about sevenfold and fivefold higher than those in roots (840 and 3,000 mg kg^?1) after exposure to 100 μM CdSO₄ and 600 μM ZnSO₄, respectively. Cd and Zn concentrations in young leaves (4,330 and 9,820 mg kg^?1) were about sixfold and twofold higher than those in mature leaves (636 and 2,620 mg kg^?1), respectively. MicroPIXE analysis showed that Zn was predominantly localized in epidermal cells in both young and mature leaves, but large amounts of Zn occurred in mesophyll cells in young leaves. Leaf tissue fractionation showed that soluble and cell wall fractions were different at the two stages of leaf growth. Young and mature leaves of S. plumbizincicola also showed different accumulation and distribution characteristics for Zn and Cd.     

Ecotoxicity of Cr, Cd, and Pb on Two Mediterranean Soils

Three potentially toxic elements [chromium (Cr), lead (Pb), and cadmium (Cd)] were tested to assess their effects on two soils of different properties and origin. The soils were a granitic soil (Haplic Arenosol), which meets the requirements of OECD ecotoxicity testing, and a calcareous soil (Calcaric Regosol) with properties often found in the Mediterranean areas. The metal concentrations used ranged from 0.001 to 5,000 mg kg^?1 soil. The effects on soil microbial activity and community composition (respirometry and polymerase chain reaction–denaturing gradient gel electrophoresis analysis), as well as the effects on plant germination and elongation (Lactuca sativa), were assessed. The toxicity of the soil water extracts was also evaluated by the growth inhibition of algal populations (Pseudokirschneriella subcapitata). Cr showed the highest level of toxicity to soil organisms in the assays performed because this element remains in soil as anionic form and is less retained by the soil solid matrix than Cd and Pb. The lowest observed–adverse effect level for Cr ranged from approximately 0.1 mg kg^?1 [substrate induced respiration (SIR) test for the granitic soil] to 10 mg kg^?1 (basal respiration and SIR tests for the calcareous soil). For Pb (SIR) and Cd (SIR and alga tests), these levels were approximately 100 mg kg^?1. Germination and algal tests showed higher sensitivity in Regosol soil than in Arenosol soil for Cr due to differences in the bioavailability between the soils. In the cases or areas where alkaline soils are abundant, these should also be considered in laboratory ecotoxicity testing to avoid underestimation of ecotoxicological risks.     

Metal Pollution (Cd,Pb, Zn,and As) in Agricultural Soils and Soybean,Glycine max,in Southern China

Crops produced on metal-polluted agricultural soils may lead to chronic toxicity to humans via the food chain. To assess metal pollution in agricultural soils and soybean in southern China, 30 soybean grain samples and 17 soybean-field soil samples were collected from 17 sites in southern China, and metal concentrations of samples were analyzed by graphite furnace atomic absorption spectrophotometer. The integrated pollution index was used to evaluate if the samples were contaminated by Cd, Pb, Zn and As. Results showed that Cd concentration of 12 samples, Pb concentration of 2 samples, Zn concentration of 2 samples, and As concentrations of 2 samples were above the maximum permissible levels in soils. The integrated pollution index indicated that 11 of 17 soil samples were polluted by metals. Metal concentrations in soybean grain samples ranged from 0.11 to 0.91 mg kg^?1 for Cd; 0.34 to 2.83 mg kg^?1 for Pb; 42 to 88 mg kg^?1 for Zn; and 0.26 to 5.07 mg kg^?1 for As, which means all 30 soybean grain samples were polluted by Pb, Pb/Cd, Cd/Pb/As or Pb/As. Taken together, our study provides evidence that metal pollution is an important concern in agricultural soils and soybeans in southern China.     

Dissipation and Dynamics of Mesotrione in Maize and Soil Under Field Ecosystem

Modified QuEChERS-HLPC (quick, easy, cheap, effective, rugged and safe) methods for the analysis of mesotrione in maize and soil were developed and validated. At three fortification levels of 0.01, 0.1 and 0.5 mg kg^?1 mesotrione, the recoveries of mesotrione in maize plants, maize and soil were in the range of 85.95 %–96.05 %, with relative standard deviations (RSD) of 2.89 %–9.83 %. The limit of quantification (LOQ) of method was 0.001 mg kg^?1 for maize and soil. In the supervised field trials, the degradation rates of mesotrione were described using first-order kinetics and mesotrione dissipation in maize plants coincided with C _t  = 1.735e^?1.0194t with the half-life 3.94 days in Tianjin, and C _t  = 4.9536e^?0.7237t with the half-life 5.10 days in Jilin. As for soil, C _t  = 20.272e^?1.208t with the half-life 2.98 days in Tianjin, and C _t  = 5.5835e^?8141t with the half-life 4.49 days in Jilin. At pre-harvest interval (PHI) of 0 and 20 days, the final residue levels of mesotrione could not be detected in maize and soil at the recommended dosage and 1.5 times recommended dosage.     

Exposure Assessment to Glyphosate of Two Species of Annelids

Adult mortality, biomass, fecundity and viability of cocoons were studied in Eisenia fetida and Octolasion tyrtaeum, in response to glyphosate exposure in soil. Exposure tests were carried out following USEPA procedure, with five concentrations of glyphosate in soil and a control. O. tyrtaeum was more sensitive to the highest concentration of glyphosate (50,000 mg kg^?1), with 100 % mortality by day 7 of exposure, compared with 71 % for E. fetida. Although biomass of O. tyrtaeum was significantly different between the control and 5,000 mg kg^?1 dose at day 14, E. fetida was not affected at that concentration, and only showed a significant weight loss after 7 days of exposure to 50,000 mg kg^?1. Adverse effects upon adult fecundity and cocoon viability were observed at glyphosate concentrations of 5,000 mg kg^?1 and above. Adverse effects were observed at concentrations that greatly exceeded the recommended field application rates of glyphosate.     

Evaluation of the Persistence and Leaching Behaviour of Thiram Fungicide in Soil,Water and Oil Palm Leaves

The residual levels and persistence of thiram in the soil, water and oil palm seedling leaves were investigated under field conditions. The experimental plots were carried out on a clay loam soil and applied with three treatments namely; manufacturer’s recommended dosage (25.6 g a.i. plot^?1), manufacturer’s double recommended dosage (51.2 g a.i. plot^?1), and control (water) were applied. Thiram residues were detected in the soil from day 0 to day 3 in the range of 0.22–27.04 mg kg^?1. Low concentrations of thiram were observed in the water and leave samples in the range of 0.27–2.52 mg L^?1 and 1.34–12.28 mg kg^?1, respectively. Results have shown that thiram has a rapid degradation and has less persistence due to climatic factors. These findings suggest that thiram is safe when applied at manufacturer’s recommended dosage on oil palm seedlings due to low residual levels observed in soil and water bodies.     

Evaluation of Sediment Contamination by Heavy Metals, Organochlorinated Pesticides, and Polycyclic Aromatic Hydrocarbons in the Berre Coastal Lagoon (Southeast France)

During the last decades, the Berre lagoon, located in southeastern France, has been deeply affected by strong contaminant inputs. Surveys of surface sediment contamination have been sparsely performed since 1964 with data often disconnected with regard to time and space. To contribute to filling this gap, this study examined the pollution status of the lagoon during a 2012 sampling. Concentrations of heavy metals (HMs) (cadmium [Cd], chromium [Cr], copper [Cu], lead [Pb], and zinc [Zn]), organochlorine pesticides (OCPs), and polycyclic aromatic hydrocarbons were examined. The available seawater metal fraction was also investigated. Water from the Vaine basin (VB; stations 1 through 6) exhibited the lowest oxygen concentration (mean O₂ % saturation 38.9 %). HM loads were in the order of Zn > Cr > Pb > Cu > Cd with overall concentration ranges of 0.20–1.40 mg kg^?1 for Cd, 17.1–119 mg kg^?1 for Cr, 7.0–60.7 g^?1 for Cu, 12.0–104 mg kg^?1 for Pb, and 56.5–215 mg kg^?1 for Zn. Although HMs accumulated at levels largely exceeding their relative natural background level of 11-fold for Pb and 80-fold for Zn, their mean concentrations decreased largely to below the acceptable legal limits. HM loads were 20 to threefold the relative corresponding value of the threshold effect level benchmark of potential biological risk. Metals were only scantly released by sediments with mean percentage release of 0.99 % for Cd and 40.2 % for Cr with a peak for this latter element of 99 % in the VB sector. In the case of OCPs, sediments appeared to be significantly polluted, especially in the VB area, with a mean lindane concentration of 0.05 mg kg^?1, which is ≤fivefold the legal threshold. Among PAHs, benzo[a]pyrene exceeded the permitted limit of 0.1 mg kg^?1 mainly in the VB sector.     

Biodegradation of Imidacloprid by Consortium of Two Soil Isolated Bacillus sp.

Imidacloprid degradation potential of bacterial cultures from sugarcane growing soils was studied in liquid culture and Bacillus aerophilus and Bacillus alkalinitrilicus showed maximum potential to degrade imidacloprid. Hence, into a clay loam soil imidacloprid was added at 50, 100, and 150 mg kg^?1 along with 45 × 10⁷ cells g^?1 soil of both species under autoclaved and unautoclaved conditions. Under autoclaved conditions imidacloprid residues were degraded after 56 days to 3.18, 5.83 and 10.48 mg kg^?1 and under unautoclaved conditions to 5.17, 6.23 and 10.31 mg kg^?1. 6-chloronicotinic acid, nitrosimine and imidacloprid-NTG metabolites were detected in measurable concentrations under both conditions. Dissipation pattern of imidacloprid did not follow first order kinetics under both sets of conditions. The half life value of imidacloprid ranged from 13 to 16 days after bacterial inoculation. This is first report of use of mixed culture of native soil bacterial isolates for remediation of imidacloprid contaminated soils.     

Toxicological Responses of the Earthworm Eisenia fetida to 18-Crown-6 Under Laboratory Conditions

The earthworm Eisenia fetida was exposed to artificial soil supplemented with 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) to investigate its effects on earthworm mortality, growth, avoidance, burrowing behavior and respiration. The results revealed that 18-crown-6 had the potential to negatively affect the behavior of earthworms. The 7-d LC₅₀ was 585 mg kg^?1 soil. Avoidance behavior was the most sensitive endpoint, with a 48-h EC₅₀ of 120 mg kg^?1 soil. Growth, burrow length and respiration showed general decreases with increasing 18-crown-6 concentrations. Behavioral endpoints and respiration may be regarded as sensitive parameters in evaluating the toxicity of this chemical to earthworms.     

Anthropogenic Contamination of Metals in Sediments of the Santa Rosalía Harbor, Baja California Peninsula

To know the environment impact on a harbor of the Santa Rosalía port on the Baja California peninsula, the concentrations of metals (Cd, Co, Cu, Mn, Pb, U and Zn) in harbor sediments were determined for 13 stations and compared with their average upper Earth´s crust abundance. The mean enrichment factors, calculated using Al as a normalizer, were higher than the unity for Ag, Ba, Bi, Cd, Co, Cu, Mn, Ni, Pb, Sb, U, V and Zn. Concentrations of slightly enriched Cd in the sediments are below the effect range low (ERL) sediment quality guidelines value only at three stations. The levels of Pb in the harbor sediments at four stations (1, 6, 9 and 11) are between the ERL (46.7 mg kg^?1) and the effect range medium (ERM) (218 mg kg^?1), and Pb content in the rest of the sediment samples is higher than the ERM, demonstrating the high extent of the anthropogenic impact of this metal on the sedimentary environment. The total concentrations of the potentially toxic elements Cu (3,390 ± 804 mg kg^?1) and Zn (1,916 ± 749 mg kg^?1) very strongly exceed their ERM, showing a high possibility of toxicological danger for marine biota, living inside or entering the harbor.     

Input and Leaching Potential of Copper,Zinc, and Selenium in Agricultural Soil from Swine Slurry

Trace elements, such as copper, zinc, and selenium, used as feed additives were determined in samples of both fresh (N = 14) and anaerobically digested (N = 6) swine slurry collected on medium- to large-size farms in northeast Spain. Considering both fresh and anaerobically digested samples, mean concentrations of zinc (1,500 mg kg^?1 dry mass [dm]) were greater than those of copper (mean 239 mg kg^?1 dm), and the selenium concentrations detected were even lower (mean 139 μg kg^?1 dm). Zinc concentrations were significantly greater in anaerobically digested samples, whereas no significant differences were found for copper or selenium. In addition, the leaching potential of zinc, copper, and selenium in cropped (lettuce heart) and uncropped experimental units subject to drip irrigation was assessed in a greenhouse experiment. Generally, the addition of swine slurry to soil (1.7 g kg^?1 dm) significantly increased zinc, copper, and selenium concentrations in leachates, which decreased in accordance with the volume of leachate eluted. Under the experimental conditions, the leaching potential of zinc and selenium was more strongly correlated with bulk parameters directly associated with the composition of the pig slurry (dissolved organic carbon, electrical conductivity, and ammonium), whereas copper mobility was more strongly associated with the crop root exudates. Although selenium has been shown to be mobile in soil, the selenium content found in the leachates did not pose any appreciable risk according to current drinking water standards.     

Alleviated Toxicity of Cadmium by the Rhizosphere of Kandelia obovata (S., L.) Yong

A pot experiment was conducted to investigate the Cadmium (Cd) toxicity alleviated by the rhizosphere of Kandelia obovata (S., L.) Yong (K. obovata), using a rhizobox with Cd concentrations of 0, 12.5, 25, 50 and 100 mg kg^?1 soil. The rhizobox used to plant K. obovata was divided into five sections by nylon cloth (S2–S5). Our results showed that pH was lower in rhizosphere than in non-rhizosphere soil. Microbial biomass C (Cmic) and N (Nmic) was stimulated in rhizosphere zone, but inhibited by Cd additions. Soil enzyme activities were significantly higher in rhizosphere (S2) than in non-rhizosphere soil (S5) (p < 0.05). In addition, DTPA-extractable Cd in different rhizosphere zone soil (S2–S5) was influenced directly under different rates of Cd supply. Moreover, Cd treatments could induce the enhancement of DTPA-extractable Cd. This study suggests that Cd toxicity can be alleviated in the rhizosphere even under high Cd supply.     

Olive Oil Mill Wastewater for Remediation of Slag Contaminated Soil

Two olive mill wastewaters (OMW) samples, OMWa and OMWb, containing different polyphenolic loads were used for decontaminating an unauthorized dump site in the Campania region, south Italy. In a bench-scale experiment, OMWa at pH 6.0 (OMWa_pH6.0) and 4.7 (OMWa_pH4.7), OMWb at pH 4.7 (OMWb_pH4.7) and OMWa free of the polyphenolic moiety polyphenol-free OMWa (PF-OMWa) were added to the soil for a 96 h contact time. At 96 h, OMWa_pH4.7 was more effective than OMWa_pH6.0, with Cd, Cu, Pb and Zn removal percentages of 30.7–68.1. Cd and Pb levels were 6.0 and 915 mg kg^?1, respectively, decreasing below the regulatory limits for industrial and commercial areas (15.0 and 1 × 10³ mg kg^?1, respectively). A threefold decrease in Zn levels was also observed from 13.5 × 10³ to 4.3 × 10³ mg kg^?1. The metal removal efficiency of PF-OMWa dropped from 30.7 % to 15.6 % for Cd and from 37.9 % to 1.3 % for Pb. OMWb_pH4.7 at 96 h was more efficient than OMWa_pH4.7, with mean removal percentages of 32.5 versus 7.8, respectively.     

The Effects of Oil Well Drill Cuttings on Soil and Rice Plant Development (Oryza sativa) Under Two Redox Conditions

Few studies have focused on the release of toxic elements from oil well drill cuttings and their effect on soil. The present study evaluated these effects using rice growth as the endpoint. Drill cuttings were collected from a Brazilian well and added in doses of 300, 3,000 and 6,000 mg kg^?1 soil, which was maintained at oxidized or reduced conditions. When the redox potential reached approximately ?250 mV, barium concentrations were determined by geochemical fractionation. Overall, doses of 300 and 3,000 mg kg^?1 promoted plant development, while a dose of 6,000 mg kg^?1 inhibited it due to the associated increase in electrical conductivity and exchangeable sodium concentration. In addition, the lower redox potential promoted solubilization of barite from the drill cuttings, which increased barium absorption by plants and translocation to grain, posing a risk to human health.     

Tungsten (W) bioavailability in paddy rice soils and its accumulation in rice (Oryza sativa)

The aim of this study was to investigate the accumulation characteristics of tungsten (W) by different indica rice cultivars from the soil and to assess the potential risks to human health via dietary intake of W in rice consumption. A total of 153 rice (ear) samples of 15 cultivars and the corresponding surface soil samples were collected from 7 cities in Fujian Province of southeastern China. The available soil W were extracted using H₂C₂O₄·2H₂O-(NH₄)₂C₂O₄·H₂O at pH 3.3). Results showed that the total soil W ranged from 2.03 mg kg^?1 to 15.34 mg kg^?1 and available soil W ranged from 0.03 mg kg^?1 to 1.61 mg kg^?1. The W concentration in brown rice varied from 7 μg kg^?1 to 283 μg kg^?1 and was significantly correlated with the available soil W. The highest mean TF_avail (transfer factor based on available soil W) was 0.91 for Te-you 627 (hybrid, indica rice), whereas the lowest was 0.08 for Yi-you 673 (hybrid, indica rice). The TF_avail decreased with the increase in available soil W, clay content, and cation exchange capacity. The consumption of the brown rice produced from the investigated areas in some cultivars by the present study may cause risks to human health.     

Modelling the Long-Term Fate of Mercury in a Lowland Tidal River. II. Calibration and Comparison of Two Models with Field Data

This study presents results of the application of two-one-dimensional/dynamic-deterministic models developed to evaluate and predict mercury contamination of a lowland river, the River Yare, Norfolk, UK. As a general indication of model performance, MODEL 1 produced a prediction of the overall mass balance of mercury in the River Yare that was 6% lower than an estimate, based on measurements, and 10% lower than the prediction provided by MODEL 2. The mercury surficial sediment concentrations calculated by MODEL 1 varied from 0.46 mg kg^?1 in 1995 (Reach 3) to 3.55 mg kg^?1 in 1986 (Reaches 6 and 7), whereas the minimum mercury concentration calculated by MODEL 2 was 0.42 mg kg^?1 in 1995 (Reach 3) and the maximum was 8.45 mg kg^?1 in 1986 (Reach 5). Average mercury concentrations experimentally measured in surficial sediments ranged from 0.47 mg kg^?1 in 1995 (Reach 3) to 8.10 mg kg^?1 in 1986 (Reach 6). MODEL 2 gave an excellent prediction of mercury in fish flesh compared with the results obtained from the actual analysis of fish flesh. Both models demonstrated good ability to simulate actual values determined for all compartments, water, surficial sediments, bottom sediments, and fish.     

Soil Enzymatic Activities as Influenced by Lead and Nickel Concentrations in a Vertisol of Central India

A pot-culture was conducted in Completely Randomized Design with three replicates to study the effect of Pb and Ni on enzymatic activities in a Vertisols. Results indicated that increasing in the levels of Pb from 0, 100, 150 and 300 mg kg^?1 soil significantly reduced the dehydrogenase activity (DHA) 38.9, 32.1, 30.9, 18.1 µg triphenylformazan g^?1 soil 24 h^?1; acid phosphatase activities 73, 61, 58, 55 µg PNP g^?1 soil h^?1 and alkaline phosphatase activities 80.7, 69.4, 66.2 and 64.0 µg PNP g^?1 soil h^?1, respectively. Application of Ni up to 100 mg kg^?1 had significantly improved the soil enzymatic activities and thereafter there was no such change up to the highest level (300 mg Ni kg^?1). Among soil enzymatic activities, DHA was more sensitive to Pb application. The findings generated through this study can be useful for managing waste water for safe disposal as well as sustainable crop production.     

Concentrations of Arsenic and Boron in Water,Sediment and the Tissues of Fish in Emet Stream (Turkey)

In this study, the concentrations of arsenic and boron were determined in the water and the sediment, as well as in the muscle tissues of Squalius cephalus, Alburnoides bipunctatus, Barbus plebejus and Capoeta tinca from Emet Stream. The fish samples were caught in May 2011 and September 2012. The metal concentrations in the water samples were as follows: arsenic was 137.1–1002 µg L^?1, and boron was 2421–14490 µg L^?1. The metal concentrations in the sediment samples were as follows: arsenic was 14.51–3317.1 mg kg^?1, and boron was 14.22–1014.01 mg kg^?1. The mean tissue concentration of arsenic was lower than the TFC and WHO limits. Boron has been identified in fish tissues at concentrations between 0.26 and 2.96 mg kg^?1. The bioaccumulation in the muscle tissues of all fish species caught from Emet Stream did not exceed the limit values.     

Persistence and Dissipation of Quinalphos in/on Cauliflower and Soil Under the Semi Arid Climatic Conditions of Karnataka, India

Persistence and dissipation of quinalphos residues in/on cauliflower was studied after giving spray applications at 2 concentrations, i.e. recommended dose of 500 g a.i. ha^?1 and double the recommended dose of 1,000 g a.i. ha^?1. Residue analysis of cauliflower curds was carried out after the third spray over a period of 15 days. Initial residues of quinalphos on cauliflower from the two treatments were 1.19 and 1.842 mg kg^?1. The residues persisted up to 15 days from both the treatments. The residues of quinalphos dissipated from both treatments with the half-life of 4.8 and 5.3 days. Based on the persistence study and maximum residue limit value of 0.05 mg kg^?1 the safe pre-harvest interval was worked out as 17 and 22 days from treatment at the recommended and double the recommended dose, respectively. Analysis of soil samples was carried out on the 15th day of sampling and residues were found to be 0.013 and 0.044 mg kg^?1.