Organismic-level acute toxicology profiling of reactive azo dyes

In the present study, organismic-level acute toxicology profile of three reactive azo dyes, viz. Reactive Blue 221, Reactive Red 195, and Reactive Yellow 145, was investigated, by using bacterial (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Listeria monocytogenes, and Bacillus subtilis), fungal (Trichoderma asperellum, Aspergillus flavus, Fusarium fujikuroi, and Rhizoctonia solani), plant (Raphanus sativus, Triticum aestivum, Sorghum bicolor, and Phaseolus mungo), and aquatic (Artemia salina and Daphnia magna) specimens. Microbial test organisms (all the six bacteria and two fungi, i.e., T. asperellum and A. flavus) and D. magna were found to be relatively more sensitive towards the reactive azo dyes and their mixture, as the EC50 values were in the range of 80–330, 135–360, and 108–242 ppm for bacteria, fungi, and D. magna, respectively (but the effect was not acutely toxic). Moreover, the effect of dye mixture was comparable tothe individual dyes in almost all the tested microbial specimens. For plant seeds, the dye mixture was found to be relatively more inhibitory towards T. aestivum and R. sativus than the individual dyes. For S. bicolor and P. mungo seeds, the effect of the dye mixture was almost identical to the individual dyes. However, in all cases, EC50 values were in the range of 950–3500 ppm, which indicates a non-toxic effect on plant seed germination potential. Likewise, the dyes and their mixture were not acutely toxic for Artemia salina larvae (more sensitive to the dye mixture) and Daphnia magna neonates (EC50, 516–950 and 108–242 ppm, respectively).     

Effects of fomesafen on soil enzyme activity,microbial population,and bacterial community composition

Fomesafen is a diphenyl ether herbicide that has an important role in the removal of broadleaf weeds in bean and fruit tree fields. However, very little information is known about the effects of this herbicide on soil microbial community structure and activities. In the present study, laboratory experiments were conducted to examine the effects of different concentrations of fomesafen (0, 10, 100, and 500 μg/kg) on microbial community structure and activities during an exposure period of 60 days, using soil enzyme assays, plate counting, and denaturing gradient gel electrophoresis (DGGE). The results of enzymatic activity experiments showed that fomesafen had different stimulating effects on the activities of acid phosphatase, alkaline phosphatase, and dehydrogenase, with dehydrogenase being most sensitive to fomesafen. On the tenth day, urease activity was inhibited significantly after treatment of different concentrations of fomesafen; this inhibiting effect then gradually disappeared and returned to the control level after 30 days. Plate counting experiments indicated that the number of bacteria and actinomycetes increased in fomesafen-spiked soil relative to the control after 30 days of incubation, while fungal number decreased significantly after only 10 days. The DGGE results revealed that the bacterial community varied in response to the addition of fomesafen, and the intensity of these six bands was greater on day 10. Sequencing and phylogenetic analyses indicated that the six excised DGGE bands were closely related to Emticicia, Bacillus, and uncultured bacteria. After 10 days, the bacterial community exhibited no obvious change compared with the control. Throughout the experiment, we concluded that 0–500 μg/kg of fomesafen could not produce significant toxic effects on soil microbial community structure and activities.     

Effects of selected metal oxide nanoparticles on Artemia salina larvae: evaluation of mortality and behavioural and biochemical responses

The aim was to investigate the toxicity of selected metal oxide nanoparticles (MO-NPs) on the brine shrimp Artemia salina, by evaluating mortality and behavioural and biochemical responses. Larvae were exposed to tin(IV) oxide (stannic oxide (SnO₂)), cerium(IV) oxide (CeO₂) and iron(II, III) oxide (Fe₃O₄) NPs for 48 h in seawater, with MO-NP suspensions from 0.01 to 1.0 mg/mL. Mortality and behavioural responses (swimming speed alteration) and enzymatic activities of cholinesterase, glutathione-S-transferase and catalase were evaluated. Although the MO-NPs did not induce any mortality of the larvae, they caused changes in behavioural and biochemical responses. Swimming speed significantly decreased in larvae exposed to CeO₂ NPs. Cholinesterase and glutathione-S-transferase activities were significantly inhibited in larvae exposed to SnO₂ NPs, whereas cholinesterase activity significantly increased after CeO₂ NP and Fe₃O₄ NP exposure. Catalase activity significantly increased in larvae exposed to Fe₃O₄ NPs. In conclusion, swimming alteration and cholinesterase activity represent valid endpoints for MO-NP exposure, while glutathione-S-transferase and catalase activities appear to be NP-specific.     

Assessment of trace metals using lichen transplant from automobile mechanic workshop in Ile-Ife metropolis,Nigeria

The level of air pollution around the automobile mechanic workshops has been generally overlooked. This study, examined the level of trace metals in automobile mechanic workshops and the suitability of using transplanted lichen thalli of Lepraria incana for measuring air pollution in such areas. Samples of the lichen thalli were transplanted into seven different sites and were attached to the bark of trees at each site. The samples were harvested from the sites after 3-month exposure. Concentrations of Pb, Cu, Cd, Fe, Zn, and S content were determined using an atomic absorption spectrophotometer. Results showed that there was a significant difference in the trace metals concentrations across the sites (p?<?0.05). The analyzed lichen samples showed a range of 91.26–119.35 ppm for Fe, 30.23–61.32 ppm for Zn, 1.25–2.45 ppm for Cu, 0.017–0.043 ppm for Cd, 0.018–0.051 ppm, and 0.37–0.42 ppm for S. From the study, sites 6 and 7 presented higher concentrations of Cd, Pb, and Zn than other sites. The enrichment factor calculated showed that Zn, Cd, and Pb were greatly enriched from the workshops. The trend in the concentration of these heavy metals suggests that activities in these workshops might become a major source of certain heavy metals in the environment and if the pollution activities persist, it might become worrisome over time.     

Synergistic action of tropospheric ozone and carbon dioxide on yield and nutritional quality of Indian mustard (Brassica juncea (L.) Czern.)

Field experiments were conducted in open top chamber during rabi seasons of 2009–10 and 2010–11 at the research farm of the Indian Agricultural Research Institute, New Delhi to study the effect of tropospheric ozone (O₃) and carbon dioxide (CO₂) interaction on yield and nutritional quality of Indian mustard (Brassica juncea (L.) Czern.). Mustard plants were grown from emergence to maturity under different treatments: charcoal-filtered air (CF, 80–85 % less O₃ than ambient O₃ and ambient CO₂), nonfiltered air (NF, 5–10 % less O₃ than ambient O₃ and ambient CO₂ ), nonfiltered air with elevated carbon dioxide (NF?+?CO₂, NF air and 550?±?50 ppm CO₂), elevated ozone (EO, NF air and 25–35 ppb elevated O₃), elevated ozone along with elevated carbon dioxide (EO?+?CO₂, NF air, 25–35 ppb O₃ and 550?±?50 ppm CO₂), and ambient chamber less control (AC, ambient O₃ and CO₂). Elevated O₃ exposure led to reduced photosynthesis and leaf area index resulting in decreased seed yield of mustard. Elevated ozone significantly decreased the oil and micronutrient content in mustard. Thirteen to 17 ppm hour O₃ exposure (accumulated over threshold of 40 ppm, AOT 40) reduced the oil content by 18–20 %. Elevated CO₂ (500?±?50 ppm) along with EO was able to counter the decline in oil content in the seed, and it increased by 11 to 13 % over EO alone. Elevated CO₂, however, decreased protein, calcium, zinc, iron, magnesium, and sulfur content in seed as compared to the nonfiltered control, whereas removal of O₃ from air in the charcoal-filtered treatment resulted in a significant increase in the same.     

Assessment of indoor airborne contamination in a wastewater treatment plant

The main objective of this work was to quantify and characterize the major indoor air contaminants present in different stages of a municipal WWTP, including microorganisms (bacteria and fungi), carbon dioxide, carbon monoxide, hydrogen sulfide ammonia, formaldehyde, and volatile organic compounds (VOCs). In general, the total bacteria concentration was found to vary from 60 to >52,560 colony-forming units (CFU)/m³, and the total fungi concentration ranged from 369 to 14,068 CFU/m³. Generally, Gram-positive bacteria were observed in higher number than Gram-negative bacteria. CO₂ concentration ranged from 251 to 9,710 ppm, and CO concentration was either not detected or presented a level of 1 ppm. H₂S concentration ranged from 0.1 to 6.0 ppm. NH₃ concentration was <2 ppm in most samples. Formaldehyde was <0.01 ppm at all sampling sites. The total VOC concentration ranged from 36 to 1,724 μg/m³. Among the VOCs, toluene presented the highest concentration. Results point to indoor/outdoor ratios higher than one. In general, the highest levels of airborne contaminants were detected at the primary treatment (SEDIPAC 3D), secondary sedimentation, and sludge dehydration. At most sampling sites, the concentrations of airborne contaminants were below the occupational exposure limits (OELs) for all the campaigns. However, a few contaminants were above OELs in some sampling sites.     

A comparative study on the decomposition of edible and non-edible oil cakes in the Gangetic alluvial soil of West Bengal

An experiment has been conducted under laboratory conditions to investigate the effect of decomposition of two edible oil cakes, viz. mustard cake (Brassica juncea L) and groundnut cake (Arachis hypogaea L), and two non-edible oil cakes, viz. mahua cake (Madhuca indica Gmel) and neem cake (Azadirachta indica Juss), at the rate of 5.0 t ha^?1 on the changes of microbial growth and activities in relation to transformations and availability of some plant nutrients in the Gangetic alluvial (Typic Haplustept) soil of West Bengal, India. Incorporation of oil cakes, in general, highly induced the proliferation of total bacteria, actinomycetes, and fungi, resulting in greater retention and availability of oxidizable C, N, and P in soil. As compared to untreated control, the highest stimulation of total bacteria and actinomycetes was recorded with mustard cake (111.9 and 84.3 %, respectively) followed by groundnut cake (50.5 and 52.4 %, respectively), while the fungal colonies were highly accentuated due to the incorporation of neem cake (102.8 %) in soil. The retention of oxidizable organic C was highly increased due to decomposition of non-edible oil cakes, more so under mahua cake (14.5 %), whereas edible oil cakes and groundnut cake in particular exerted maximum stimulation (16.7 %) towards the retention of total N in soil. A similar trend was recorded towards the accumulation of available mineral N in soil and this was more pronounced with mustard cake (45.6 %) for exchangeable NH₄ ⁺ and with groundnut cake (63.9 %) for soluble NO₃ ^?. The highest retention of total P (46.9 %) was manifested by the soil when it was incorporated with neem cake followed by the edible oil cakes; while the available P was highly induced due to the addition of edible oil cakes, the highest being under groundnut cake (23.5 %) followed by mustard cake (19.6 %).     

Alteration of antioxidant enzymes and impairment of DNA in the SiO2 nanoparticles exposed zebra fish (Danio rerio)

The incorporation of nanoparticles in industrial and biomedical applications has increased significantly in recent years, yet their hazardous and toxic effects have not been studied extensively. While standard toxicological test methods are generally capable of detecting the toxic effects, the choice of relevant methods for nanomaterials is still discussed. Among the various oxide nanomaterials, silica nanoparticles are widely used in biological applications that include nano-medicine. But studies on adverse effects of silica nanoparticle exposure to fish remain unclear. Therefore, the present study was designed to investigate the oxidative toxic effects of silicon dioxide nanoparticles using fish model. The size of the SiO₂ nanoparticles was between 68 and 100 nm which was confirmed by X-ray diffractometer, dynamic light scattering, scanning electron microscope and transmission electron microscope. The zebra fish were exposed to sub-lethal concentrations (5 and 2.5 mg/L) of characterized SiO₂ nanoparticles for a period of 7 days. After 7 days, SiO₂ nanoparticle-treated fishes were sacrificed, and tissues such as liver, muscle and gill were dissected out for the analysis of antioxidant enzymes and DNA fragmentation. The DNA profiles were analysed in the tissues of zebra fish that treated with SiO₂ nanoparticles. Tissues of fish from clean water were used as control, and DNA profiles were analysed. It is found that DNA from control tissues was intact, whereas the tissues treated with SiO₂ were all fragmented. SiO₂ nanoparticle-mediated antioxidant enzymes activities, such as catalase, superoxide dismutase, glutathione (GSH)-S-transferase, glutathione reductase and GSH, in the tissues of zebra fish were measured. The results revealed that alteration of antioxidant enzymes due to SiO₂ nanoparticle can be considered as a biomarker to SiO₂-mediated oxidative stress in biological samples.     

Utility of nematode Acrobeloides nanus for assessing subacute toxicity of heavy metals

Nematodes offer perspectives for ecotoxicological research as their characters and most of toxicity assessment focused on Caenorhabditis elegans. In order to enrich the limited numbers of nematode species used for toxicity test, this study assessed the subacute effects of copper and zinc to the life history characters of nematode Acrobeloides nanus. Compared with control, the 72-h effective concentration (EC)₅₀, EC₂₀, and EC₁₀ for reproduction in A. nanus were 1.35, 0.49, and 0.20 mg/L, respectively, for Cu and 829.46, 330.29, and 163.90 mg/L, respectively, for Zn. The EC₁₀ for growth at 72 h and 96 h of the 2nd generation in A. nanus were 1.13 and 0.97 mg/L, respectively, for Cu, and 353.46 and 284.20 mg/L, respectively, for Zn. During the exposure, the effect of copper–zinc on reproduction was less than additive, and the copper–zinc effect on growth changed from a synergistic to antagonistic.     

Freshwater shrimp (Palaemonetes australis) as a potential bioindicator of crustacean health

Palaemonetes australis is a euryhaline shrimp found in southwestern Australian estuaries. To determine if P. australis is a suitable bioindicator species for monitoring the health of estuarine biota, they were exposed to measured concentrations of the polycyclic aromatic hydrocarbon, benzo[a]pyrene (B[a]P) at 0.01, 0.1, or 1?ppm for 14?days under laboratory conditions. At the end of exposure the shrimp were sacrificed for biomarker [ethoxycoumarin O-deethylase (ECOD), 8-oxo-dG concentration, and sorbitol dehydrogenase (SDH) activity] analyses. Gender did not appear to influence biomarker responses of the shrimp in this study. ECOD activity was induced in the treatment groups in a linear fashion from three (0.01?ppm) times to 12 (1?ppm) times the negative controls. 8-oxo-dG concentration was reduced three times in treatment groups below the controls suggesting impaired DNA repair pathways. There was no increase in SDH, signifying hepatopancreatic cell damage had not occurred in any treatment group. The response of P. australis to B[a]P exposure indicates that this crustacean is suitable bioindicator species for both laboratory studies and field monitoring. A combination of ECOD and SDH activities and 8-oxo-dG concentration represent a suitable suite of biomarkers for environmental monitoring of the sublethal effects of organic pollution to crustaceans from an estuarine environment.     

Indoor air quality in university environments

This study evaluates the airborne microflora in research laboratories of the University of Chieti (Italy). A quali-quantitative evaluation of the index microbial air contamination was performed using the settle plate method. The microbial air contamination was evaluated during 6 months in three university buildings (A, B, and C). Nutrient agar plates were exposed, monthly, for 1 h at the morning and the afternoon to evaluate the colony forming units per plate per hour. Together with the quantitative analysis, the most frequent bacterial and fungal colonies isolated were also characterized. Moreover, in each sampling, the number of the occupants in each room was recorded to evaluate a possible relationship with the microbial pollution. The microbial concentration was always within the limit values defined for these environments. Buildings A and C displayed a seasonal fluctuation of airborne microflora with the increase in microbial concentration in the warmer season (April to June) in respect to the colder period (October to December). The most common microorganisms detected in the indoor air of the examined buildings were Gram-positive bacteria, belonged to the genera Staphylococcus, Bacillus, and Actinomyces. Data presented here underline the useful monitoring of the research university laboratories also emphasizing the effectiveness of the settle plate method.     

Methane oxidation and abundance of methane oxidizers in tropical agricultural soil (vertisol) in response to CuO and ZnO nanoparticles contamination

There is worldwide concern over the increase use of nanoparticles (NPs) and their ecotoxicological effect. It is not known if the annual production of tons of industrial nanoparticles (NPs) has the potential to impact terrestrial microbial communities, which are so necessary for ecosystem functioning. Here, we have examined the consequences of adding the NPs particularly the metal oxide (CuO, ZnO) on CH₄ oxidation activity in vertisol and the abundance of heterotrophs, methane oxidizers, and ammonium oxidizers. Soil samples collected from the agricultural field located at Madhya Pradesh, India, were incubated with either CuO and ZnO NPs or ionic heavy metals (CuCl₂, ZnCl₂) separately at 0, 10, and 20 μg g^?1 soil. CH₄ oxidation activity in the soil samples was estimated at 60 and 100 % moisture holding capacity (MHC) in order to link soil moisture regime with impact of NPs. NPs amended to soil were highly toxic for the microbial-mediated CH₄ oxidation, compared with the ionic form. The trend of inhibition was Zn 20?>?Zn 10?>?Cu 20?>?Cu 10. NPs delayed the lag phase of CH₄ oxidation to a maximum of 4-fold and also decreased the apparent rate constant k up to 50 % over control. ANOVA and Pearson correlation analysis (α?=?0.01) revealed significant impact of NPs on the CH₄ oxidation activity and microbial abundance (p?<?0.0001, and high F statistics). Principal component analysis (PCA) revealed that PC1 (metal concentration) rendered 76.06 % of the total variance, while 18.17 % of variance accounted by second component (MHC). Biplot indicated negative impact of NPs on CH₄ oxidation and microbial abundance. Our result also confirmed that higher soil moisture regime alleviates toxicity of NPs and opens new avenues of research to manage ecotoxicity and environmental hazard of NPs.     

Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian contaminated systems

Samples of soil, water, and sediments from industrial estates in Lagos were collected and analyzed for heavy metals and physicochemical composition. Bacteria that are resistant to elevated concentrations of metals (Cd^2?+?, Co^2?+?, Ni^2?+?, Cr^6?+?, and Hg^2?+?) were isolated from the samples, and they were further screened for antibiotic sensitivity. The minimum tolerance concentrations (MTCs) of the isolates with dual resistance to the metals were determined. The physicochemistry of all the samples indicated were heavily polluted. Twenty-two of the 270 bacterial strains isolated showed dual resistances to antibiotics and heavy metals. The MTCs of isolates to the metals were 14 mM for Cd^2?+?, 15 mM for Co^2?+? and Ni^2?+?, 17 mM for Cr^6?+?, and 10 mM for Hg^2?+?. Five strains (Pseudomonas aeruginosa, Actinomyces turicensis, Acinetobacter junni, Nocardia sp., and Micrococcus sp.) resisted all the 18 antibiotics tested. Whereas Rhodococcus sp. and Micrococcus sp. resisted 15 mM Ni^2?+?, P. aeruginosa resisted 10 mM Co^2?+?. To our knowledge, there has not been any report of bacterial strains resisting such high doses of metals coupled with wide range of antibiotics. Therefore, dual expressions of antibiotics and heavy-metal resistance make the isolates, potential seeds for decommissioning of sites polluted with industrial effluents rich in heavy metals, since the bacteria will be able to withstand in situ antibiosis that may prevail in such ecosystems.     

Heavy metal uptake and its effect on macronutrients, chlorophyll, protein, and peroxidase activity of Paspalum distichum grown on sludge-dosed soils

This study assessed the heavy metal (Cr, Mn, Ni, Cu, Zn, and Pb) uptake and its effect on biochemical parameters in Paspalum distichum, a wetland plant. Sludge collected from Bhalswa waste dump, New Delhi, was used as heavy metal source and dosed in different proportions viz. 20%, 40%, 60%, and 80% to the garden soil. The plants accumulated metals mostly in belowground organs. The metal accumulation followed the order: Cr>Mn>Cu>Zn>Ni>Pb. The range of heavy metal concentration in tissue of belowground organs after 180 days of growth was 1,778.65–4,288.01 ppm Cr, 828.11–1,360 ppm Mn, 236.52–330.07 ppm Ni, 155.79–282.35 ppm Cu, 27.05–91.16 ppm Zn, and 27.09–50.87 ppm Pb. The biochemical parameters viz. chlorophyll and protein contents and peroxidase (POD) activity exhibited no considerable adverse effect indicating the plants’ tolerance towards heavy metals. The high POD activity and synthesis of new protein bands at high sludge-dosed plants were also in support of this fact.     

Bioaccumulation and toxicity of arsenic in cyanobacteria cultures separated from a eutrophic reservoir

The bioaccumulation and toxicity of arsenate (arsenic (As)(V)) was studied using three cultures of cyanobacterial species—Oscillatoria tenuisa, Anabaena affinis, and Microcystis aeruginosa—that were isolated from a eutrophic reservoir. The As(V) uptake depended on the cyanobacterial species, the growth phase of the cyanobacteria, the duration of exposure, and the initial concentration of As(V). The specific growth rates of the three cultures immediately following the logarithmic phase were 0.033–0.041 L/day when the initial concentration of As(V) was 50 mg/L. These rates were 2.3–3.6 times less than those in the original culture medium without As(V). The rate of intake of As(V) in the logarithmic phase cultures greatly exceeded that in the stationary cultures. The accumulation of As(V) by the three cultures increased rapidly within 1 week from the initial value of 3.23?×?10^?2–5.40?×?10^?2 to 5.06?×?10^?1–6.73?×?10^?1 ng/cell in the logarithmic phase. The effective concentrations (EC₅₀) of As(V) for inhibiting the growth of the three cyanobacterial species growth of at 72 h followed the order Oscillatoria tenuisa (3.8 mg/L)?>?A. affinis (2.6 mg/L)?>?M. aeruginosa (1.2 mg/L). The cyanobacterial species that was most sensitive to As(V) was M. aeruginosa. Preliminary results from SEM-map studies suggest most of the As(V) in Microcystis aeruginosa accumulated in the cytoplasm (intercellular), while in O. tenuisa and A. affinis, a large proportion of As(V) bound to the cell wall (extracellular). These differences were understood with reference to the variation among the metabolic properties and morphological characteristics of the cyanobacterial species.     

Investigation of the bacterial load and antibiotic susceptibility of dental units

The aim of this study was to evaluate the bacterial contamination level and to determine the antibiotic susceptibility of the isolated bacteria from dental unit waterlines (DUWLs) in Istanbul. Bacterial quality of DUWLs is very important, as patients and dental staff are regularly exposed to water and aerosols generated by the unit. If opportunistic pathogens such as Staphylococcus aureus, Pseudomonas aeruginosa, and Legionella pneumophila are present in DUWLs, patient and dental staff can be infected. One hundred water samples were collected from high-speed drills and input waters from 50 dental units. Aerobic heterotrophic bacteria counts and the presence of Legionella, Pseudomonas, oral streptococci, and Staphylococcus were investigated in dental unit waters and aerosol samples. In addition, the antibiotic susceptibility of the isolated and identified bacteria from DUWLs was examined. This research found that 37 out of 50 dental unit water samples exceeded the American Dental Association’s limit of 200 colony-forming units (CFU)/mL^?1. Legionella, oral streptococci, and S. aureus were not detected in any water or aerosol samples, but P. aeruginosa was isolated in three DUWLs. Also, Pseudomonas and Staphylococcus were found in water and aerosol samples. Cefoperazone, ofloxacin, gentamicin, ciprofloxacin, and piperacillin were the most effective antibiotics against the isolated bacteria from DUWLs.     

Assessment of imidacloprid degradation by soil-isolated Bacillus alkalinitrilicus

Imidacloprid is extensively used on a broad range of crops worldwide as seed dressing, soil treatment, and foliar application. Hence, the degradation potential of bacterial strains from sugarcane-growing soils was studied in liquid medium for subsequent use in bioremediation of contaminated soils. The microbe cultures degrading imidacloprid were isolated and enriched on Dorn’s broth containing imidacloprid as sole carbon source maintained at 28 °C and Bacillus alkalinitrilicus showed maximum potential to degrade imidacloprid. Clay loam soil samples were fortified with imidacloprid at 50, 100, and 150 mg kg^?1 along with 45?×?10⁷ microbe cells under two opposing sets of conditions, viz., autoclaved and unautoclaved. To study degradation and metabolism of imidacloprid under these two conditions, samples were drawn at regular intervals of 7, 14, 28, 35, 42, 49, and 56 days. Among metabolites, three metabolites were detected, viz., 6-chloronicotinic acid, nitrosimine followed by imidacloprid-NTG under both the conditions. Total imidacloprid residues were not found to follow the first-order kinetics in both types of conditions. This paper reports for the first time the potential use of pure cultures of soil-isolated native bacterium B. alkalinitrilicus and also its use along with natural soil microflora for remediation of imidacloprid-contaminated soils.     

Bioaccumulation of nutrient elements from fly ash-amended soil in Jatropha curcas L.: a biofuel crop

Fly ash (FA) from coal-burning industries may be a potential inorganic soil amendment; the insight of its nutrient release and supply to soil may enhance their agricultural use. The study was conducted to assess the ability of fly ash (a coal fired thermal plant waste) to reduce soil fertility depletion and to study bioaccumulation of mineral nutrients in Jatropha curcas grown on soils amended with fly ash. Fly ash was amended to field soil at six rates (0, 5, 10, 20, 40, and 70 % w/w) on which J. curcas was grown. After 8 months of growth, the height of jatropha plants was significantly increased at 5 and 10 % FA-amended soil, whereas, biomass significantly increased at 5, 10, and 20 % FA-amended soil compared to control soil (0 % FA). Leaf nutrients uptake, followed by stems and roots uptake were highly affected by fly ash amendment to soil. Most of nutrients accumulation were increased up to 20 % fly ash and decreased thereafter. The results of available nutrient analysis of soil revealed that availability of nitrogen, potassium, sulfur, copper, iron, mangnese, and zinc declined significantly at higher levels of fly ash amendments, whereas, availability of phosphorus increased at these levels. However, pH, organic carbon, and available boron were not influenced significantly by fly ash amendment to soil. Microbial biomass C, N, and ratio of microbial-C to organic C were significantly reduced at 20 % fly ash and higher amounts. This study revealed that J. curcas plants could gainfully utilize the nutrients available in fly ash by subsequently amending soil.     

Kinetics of degradation of carbendazim by B. subtilis strains: possibility of in situ detoxification

Food safety is a global concern due to the increased use of pesticides in agriculture. In grapes, carbendazim is one of the frequently detected fungicides. However, it is amenable to biodegradation. In this study, we aimed to assess the degradation of carbendazim by four Bacillus subtilis strains, which had earlier shown potential for biocontrol of grape diseases. In liquid medium, each of the four strains, namely, DR-39, CS-126, TL-171, and TS-204, could utilize carbendazim as the sole carbon source. The half-life was minimized from 8.4 days in the uninoculated spiked control to 4.0–6.2 days by the four strains. In Thompson Seedless sprayed with carbendazim at 1.0 g L^?1, the residue on grape berries in control was 0.44 mg kg^?1 after 25 days of application, whereas in grapes treated with the four B. subtilis strains, the residues had decreased to 0.02 mg kg^?1. The degradation kinetics showed low half-lives of 3.1 to 5.2 days in treated grapes as compared to 8.8 days in control. In inoculated soils, the half-lives were 5.9 to 7.6 days in autoclaved and 6.5 to 7.2 days in nonautoclaved soils as compared to 8.2 and 8.0 days in respective controls. The growth dynamics of these strains in all the three matrices was not affected by presence of carbendazim. Bacillus strains TS-204 and TL-171 showed higher degradation rate than the other two strains in all the three matrices and show promise for in situ biodegradation of carbendazim.     

Mortality factors and lead contamination of wild birds from Korea

Wild birds have frequently been found dead in their natural habitats, but little is known about what ecological stressors may impact health of wild populations. Here, we report the potentially harmful lead (Pb) levels in tissues along with necropsies on 69 individuals of cranes, raptors, and waterfowl found dead between 2000 and 2003 in Korea. In all samples diagnosed, trauma (n?=?22), severe emaciation (n?=?15), and infectious diseases (n?=?11) were identified. In the survey, injury with Pb shot or bullet fragments was associated with three of the deaths; one of three showed lesions suggestive of Pb poisoning in the tissues. Of 69 birds, 12 had >25 ppm dry wt. (equivalent to 8 ppm wet wt.) in liver or kidney, which is known to be a potentially lethal level of Pb in wild birds. Three individuals had hepatic Pb levels of 101.3 ppm (Whooper swan), 120.4 ppm (Great white-fronted goose), and 1,059 ppm (Mandarin duck), with evidence of Pb pellets in their gizzard. This study suggests that many birds examined may be suffering from excessive Pb exposure that may be of health concern with respect to a potential cause of their mortality. The need for additional research is heightened when considering that some migrants are classified as a globally protected species by the International Union for the Conservation of Nature.