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1.
Greenhouse tests were conducted to study the effect of chelates on the phytoextraction of cadmium and lead, and the rhizodegradation of used engine oil present as a mixed contaminant in a sandy soil. Indian mustard plants were grown in test pot soil for 30 days and chelates ethylenediamine tetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) were individually applied to the test soil. The soil was spiked earlier with 50 mg kg?1 of CdCl2, 500 mg kg?1 of PbCl2 and 500 mg kg?1 of used engine oil to form the mixed soil contaminant. At the same concentration of chelates, EDTA was found to be more effective than EDDS in increasing the concentration of metal contaminants Cd and Pb in the plant. Compared to EDDS, EDTA was also more effective in promoting rhizodegradation of the organic contaminant formed by used engine oil. The study demonstrated that the application of chelates to soils containing mixed contaminants such as heavy metals (Cd and Pb) and organics (used engine oil) can simultaneously assist metal accumulation at higher concentrations in the biomass of Indian mustard plant and also reduce the amount of used engine oil in the soil through rhizodegradation.  相似文献   

2.
Biochar is considered a promising amendment for the reduction of metal concentration in plants; however, the effects of biochar in terms of dose and feedstock on metal uptake by plants remain widely unclear. In the current study, three individual biochars were prepared at 450 °C from different feedstocks (wheat straw, sukh chain (Pongamia pinnata), and cotton sticks). The main aim was to evaluate their ability to remediate cadmium (Cd)-spiked soil in terms of growth response and Cd uptake by wheat (Triticum aestivum) tissues. Biochars were separately applied at 0, 1, and 2% (w/w) in Cd-spiked soil and wheat was grown until maturity in pots and then morphological and physiological parameters and Cd concentrations in grains, roots, and shoots were determined. The post-harvest soil was analyzed for extractable Cd concentrations. Plants grown in Cd-spiked soil treated with biochars had higher seed germination, lengths of roots, shoots, and spikes, grains per spike and leaf relative water contents, chlorophyll contents, and dry weight of roots, shoots, and grains as compared to the untreated control. Biochar treatments significantly decreased the Cd concentrations in shoots, roots, and grains as well as total Cd uptake by grains. Soil extractable Cd concentrations were significantly decreased with biochar treatments. The application of 2.0% wheat straw biochar was the most efficient treatment in increasing grain yield and decreasing Cd in grains as well as soil extractable Cd than the other two biochars and doses applied.  相似文献   

3.
Soil contamination with cadmium has become major concern all over the world because of its adverse impacts on ecosystem health and agricultural land. Soil amendment with biochar may have varied effects on physical and chemical properties of soil. The objective of the study was to explore the impact of sugarcane filter-cake biochar on physiological performance and growth of lettuce in an aged soil. Four different doses (0, 1.5%, 3%, and 5%) of biochar were used in the soil and conditioned for 1 month. After this, lettuce seedlings were grown in the soil. The results showed that the biochar treatment improved the fresh and dry biomass of leaves and roots as well as plant height while diminished the bioavailability of cadmium from the soil. As compared to control, biochar significantly enhanced the chlorophyll content in lettuce leaves. Due to the biochar amendment, the oxidative stress decreased in lettuce shoots over the control. As compared to control, concentration of cadmium in lettuce significantly decreased after the application of biochar. It was concluded that biochar could mitigate the toxicity of cadmium in lettuce by altering the biochemical and physiological processes in cadmium contaminated soil.  相似文献   

4.
Remediation of heavy-metal-contaminated sediment is often hampered by the availability of heavy metals to the added chemical agents because the heavy metals are often shielded by the sediment matrix. Effective heavy-metal extraction technique becomes an important factor in enhancing the treatment efficiency. A novel extraction/washing technique utilizing chelating agent and elevated pressure in consecutive cycles of compression and decompression has been developed for heavy-metal-contaminated sediment washing in the presence of chelating agent. In this study, the optimal operational conditions of pressure-assisted cyclic washing of Cu-contaminated sediments (initial Cu concentration = 23.177 mg/kg) were determined in a laboratory-scale system. The control factors included applied pressure level, washing time, applied chelant [ethylenediamine-tertraacetic (EDTA)] concentration (0.01–0.5 M), pressure times, and application of consecutive batches washing. Results from the bench-scale study showed that up to 70 % of Cu can be removed from the sediments when 10 atm of pressure was applied for washing. The efficiency dropped to 55 % when the pressure dropped to 6 atm. Under the same operational conditions, the optimal cyclic washing time was 60 min. Results from the particle size analyses indicate that the mean particle size dropped from 100 to 50 μm after the pressure-assisted cyclic washing. Thus, cyclic pressure caused the fracture of sediment aggregates resulting in the exposure of Cu to chelating agents. With the assistance of pressure cyclic system, the total washing time and the amount of added chemical agent used can be significantly reduced.  相似文献   

5.
Anaerobic digestate is a by-product from the biogas production which can be applied as replacement for mineral fertilizers. But digestate has both phytostimulating and phytotoxic effects on plants. Fertilizers toxicity and phytotoxicity should be measured to preserve the environment. The phytotoxicity of digestate from anaerobic digestion of swine manure was evaluated using several official protocols. Germination toxicity was tested on Pisum sativum L. and Lepidium sativum L., roots elongation on Hordeum vulgare L. and shoots elongation on Lactuca sativa L. To determine digestate growth toxicity, pot experiments were performed on two Solanum lycopersicum L. cvs. Digestate dilutions ranging from 5 to 30 % were tested in the different assays. Standard protocols were applied to non-standard species: Cichorium endivia L. (shoots elongation) and two Capsicum annuum L. cvs (pot trials). Digestate concentrations stimulating germination and early life stages were between 2 and 3 %. Pot trials suggested that during more advanced growth stages, digestate can be applied at 20–30 %. The main finding was that to minimize digestate phytotoxicity, direct contact with germinating seeds or young plants should be avoided. During plants late growth, digestate administration might be increased carefully to minimize salinity and ammonia excess. Soil samples from the pot trials were analysed at the starting, mid- and final experimental stages. Conclusion was that digestate utilization may have also a soil liming effect, increasing electric conductivity, pH and contrasting soil acidification.  相似文献   

6.
Anthropogenic chelating agents and biological chelating agents produced by indigenous organisms may dissolve CrIII (hydr)oxides in soils and sediments. The resulting dissolved CrIII-chelating agent complexes are more readily transported through porous media, thereby spreading contamination. With this work, we examine chelating agent-assisted dissolution of amorphous chromium hydroxide (ACH) by the (amino)carboxylate chelating agents iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), tricarballylic acid (TCA), citric acid (CIT), ethylenediaminetetraacetic acid (EDTA), trans-1,2-cyclohexanediaminetetraacetic acid (CDTA), and trimethylenediaminetetraacetic acid (TMDTA). The extent of chelating agent adsorption onto ACH increased quickly over the first few hours, and then increased more gradually until a constant extent was attained. The extent of chelating agent adsorption versus pH followed “ligand-like” behavior. All chelating agents with the exception of TCA and IDA effectively dissolved significant amounts of ACH within 10 days from pH 4.0 to 9.4. IDA dissolved ACH below pH 6.5 and above pH 7.5. Rates of ACH dissolution normalized to the extent of chelating agent adsorption were pH dependent. IDA, NTA, CIT, and CDTA exhibited an increase in normalized dissolution rate with decreasing pH. EDTA and TMDTA exhibited a maximum in normalized dissolution rate near pH 8.5. Use of acetic acid as a pH buffer in experiments decreased the extent of chelating agent adsorption for IDA, NTA, and CIT but increased normalized rates of chelating agent-assisted dissolution for all chelating agents except EDTA. The results from this study provide the necessary information to calculate the extents and time scales of ACH dissolution in the presence of (amino)carboxylate chelating agents.  相似文献   

7.
The generation of electricity has been identified as one of the main pollutant activities, and some studies have established an increment of heavy metals in soil in the areas surrounding these plants. The aim of this study was to evaluate the soil concentrations of heavy metals in the zone surrounding a thermoelectric power in Mexico. Thirty-two top soil samples (0–5 cm) were collected; additionally, four depth profiles (1 m) were investigated. Median concentrations for chromium, vanadium, nickel, mercury, and cadmium were 47, 47, 73, 0.02, and 0.01 mg/kg, respectively. Higher Cr, Ni, and V concentrations were observed in the soil depth profiles located closer to the plant in comparison with the concentrations found in the soil depth profile located further away from the plant; these results may indicate a possible accumulation of these metals. The geoaccumulation index results indicated that most of the sites were in the classifications of unpolluted and unpolluted to moderately polluted (classes 1 and 2). The statistical results showed that downwind of the plant in relation to the prevailing winds, there was a strong correlation between soil concentrations of chromium, copper, nickel, and vanadium. Based on the results of this study, it can be concluded that the use of fuel oil at the thermoelectric plant contributed to the accumulation of vanadium and nickel in the soil of the surrounding areas, as well as chromium and copper.  相似文献   

8.
Ethylenediaminetetraaceticacid (EDTA) has been proven to be an efficient soil washing liquid to remove metal contaminants from soils. However, EDTA may cause secondary pollution due to its low biodegradability if it is not recycled or destroyed in the washing process. Thus, it is necessary to recycle and recover EDTA for sustainable use. In this paper, the extracting performance of fresh EDTA was firstly studied as a function of EDTA concentration, liquid/sediment (L/S) ratio and pH of the solution, and also extraction time. Then sodium tetraethylenepentamine-multi dithiocarbamate (TEPA-DTC), a heavy metals capturing agent, was synthesized on the base of the research of LIU-Lihua. Compared with Na2S and DDTC, TEPA-DTC shows strong chelating capacity, because it has functional groups of dithiocarbamate that could strongly chelate heavy metals and capture metal ions from Me-EDTA to form precipitates, allowing us to reclaim the EDTA during the process of soil washing. Three divalent heavy metals were investigated (Pb, Cd, and Cu). These three metals could almost precipitate completely with TEPA-DTC under the dosage of 300 mg/l, and EDTA was regenerated. The recovered EDTA was used again in three cycles of soil washing, and the amount of heavy metals extracted just slightly decreased each cycle.  相似文献   

9.
A pot culture experiment was conducted to study impact and interaction of multi-metals on growth, yield and metals uptake by spinach (variety All Green). Three levels of each chromium (0, 50 and 100 mg/kg), cadmium (0, 1 and 2 mg/kg) and zinc (0, 10 and 20 mg/kg) in combinations (total treatments 3 × 3 × 3 = 27) were applied in a Vertisol (5 kg). The results showed that increasing the concentration of chromium, cadmium and zinc in soil enhanced the respective metal concentrations in spinach root and shoot. When cadmium at 2 mg/kg along with chromium at 100 mg/kg soil was applied, chromium concentration and uptake were decreased in root and shoot. Meanwhile, zinc application had no significant effect on chromium uptake and concentration in spinach biomass. From the results, it was concluded that cadmium at higher dose had an antagonistic effect over chromium. On the other hand, in chromium, cadmium and zinc combinations particularly at their higher levels, a competition among each other was found. Therefore, the findings could be used as guidelines for controlling and management of heavy metals pollution in farmland.  相似文献   

10.
Pollution by heavy metals presents an environmental concern, and their toxicity threats soil, water, animals and human health. Phytoremediation can be used as a solution to remediate contaminated soils. The aim of this study was to identify native plants collected from tailings: material of Pb–Zn mine sites of Fedj Lahdoum and Jebel Ressas (two abandoned mines located, respectively, in the northwest of Tunisia and in the south of Tunis City). The tolerance of plant to heavy metals (lead, zinc and cadmium) is evaluated. Soil samples were collected and analyzed for Pb, Zn and Cd concentration. The total soil Pb, Zn and Cd are, respectively, reached 6132 mg kg?1, 11,052 mg kg?1 and it doesn’t exceed 479 mg kg?1 for Cd. The highest content of Zn in plants was detected in shoots of Rumex bucephalophorus (1048 mg kg?1), and the highest Pb concentration was detected in roots of Chrysopogon zizanioides (381 mg kg?1), while for Cd Silene colorata it accumulated the highest content in roots (51 mg kg?1). From all plants, only 12 have a translocation factor for Pb which is higher than one. Among all plants, only 17 have a translocation factor that is higher than one for Zn, while for Cd only 13 plants indicate TF > 1. As for the biological absorption coefficient, all samples indicate a rate which is lower than one. These plants can be primarily hyper accumulators and useful in remediation of lead- and zinc-contaminated soils after further biochemistry researches in mechanism of accumulation and translocation of heavy metals in plants.  相似文献   

11.
The spatial heterogeneity of soil nutrients influences crop yield and the environment. Previous research has focused mainly on the surface layer, with little research being carried out on the deep soil layers, where high root density is highly related to crop growth. In the study, 610 soil samples were collected from 122 soil profiles (0–60 cm) in a random-sample method. Both geostatistics and traditional statistics were used to describe the spatial variability of soil organic matter (SOM) and total nitrogen (TN) deeper in the soil profile (0–60 cm) with high root density from a typical Mollisol watershed of Northeast China. Also, the SOM and TN in farmland and forest (field returned to forest over 10 years) areas was compared. The spatial autocorrelations of SOM at 0–50 cm depth and TN at 30–60 cm depth were strong, and were mainly influenced by structural factors. Compared to farmland, SOM and TN were typically lower in the 0–30 cm depth of the forest areas, while they were higher in the 30–60 cm depth. As well, both SOM and TN decreased from the 0–20 cm layer to the 30–40 cm layer, and then discontinues, while they continuously decreased with increasing soil depth in the farmland. SOM and TN were typically higher at the gently sloped summit of the watershed and part of the bottom of the slope than at mid-slope positions at the 0–30 cm depth. SOM and TN were lower on the back slope at the 30–60 cm depth, but were higher at the bottom of the slope. Also, the spatial distribution of the carbon storage and nitrogen storage were all highest at the bottom of the slope and part of the summit, while they were lowest in most of back slope in depth of 0–60 cm, and mainly caused by soil loss and deposition. SOM at 0–60 cm and TN at 0–40 cm greater than the sufficiency level for crop growth (3.7–79.2 and 0.09–3.09 g kg?1, respectively) covered 99 % of the total area, yet for TN, over 35 % of the total area was less than the insufficiency level at the 40–60 cm depth. Generally, accurately predicting SOM and TN is nearly impossible when based only on soil loss by water, although the fact that variability is influenced by elevation, soil loss, deposition and steepness, was shown in this research. Nitrogen fertilizer and manure application were needed, especially in conjunction with conservation tillage in special conditions and specific areas such as the back slope, where soil loss was severe and the deep soil that lacked TN was exposed at the surface.  相似文献   

12.
The goal of this study was to evaluate the soil properties and their modifications within the rhizosphere of spontaneous vegetation as key factors to assess the phytomanagement of a salt marsh polluted by mining wastes. A field survey was performed based on a plot sampling design. The results provided by the analyses of rhizospheric soil (pH, electrical conductivity (EC), organic carbon, total nitrogen, etc.) and metal(loid)s’ phytoavailability (assessed by EDTA) were discussed and related to plant metal uptake. The averages of pH and EC values of the bulk soil and rhizospheric samples were in the range of neutral to slightly alkaline (pH 7–8) to saline (>2 dS m?1), respectively. Heavy metal and As concentrations (e.g. ~600 mg kg?1 As, ~50 mg kg?1 Cd, ~11,000 mg kg?1 Pb) were higher in the rhizosphere for both total and EDTA-extractable fraction. Phragmites australis uptaked the highest concentrations in roots (e.g. ~66 mg kg?1 As, ~1,770 mg kg?1 Zn) but not in shoots, for which most of plant species showed low values for Zn (<300 mg kg?1) but not for Cd (>0.5 mg kg?1) or Pb (~20–40 mg kg?1). Vegetation distribution in the studied salt marsh looked to be more affected by salinity than by metal pollution. The free availability of water for plants and the incoming nutrient-enriched effluents which flow through the salt marsh may have hindered the metal(loid)s’ phytotoxicity. The phytomanagement of these polluted areas employing the spontaneous vegetation is a good option in order to improve the ecological indicators and to prevent the transport of pollutants to nearby areas.  相似文献   

13.
Municipal solid waste compost and cattle manure are used as organic fertilizers in agriculture and horticulture. These wastes, however, may also have some negative effects on the agricultural environment. This study investigates the effects of municipal solid waste compost of Kerman (MSC) and cattle manure (CM) on availability of the heavy metal in calcareous soil (extractable with EDTA) in greenhouse conditions. The MSC and CM were mixed thoroughly with soil at rates of 0%, 2%, and 4% of dry matter. After 90 days of incubation, the soil samples were analyzed. Addition of levels of each two organic wastes into soil significantly decreased the soil pH and increased the soil EC as compared with control (unamended soil).The available contents (EDTA-extractable) of Cd, Pb, Cu, Zn, and Cu in the soil samples were increased because of each two organic treatments applied. The heavy metal contents in the soil samples amended with MSC were more than CM. The heavy metal contents of organic wastes were well below the maximum allowed by USEPA. It is recommended that in Iran, the legal maximum permissible limit for heavy elements in organic wastes must be determined.  相似文献   

14.
The effect of glucose, chicken manure, and filter mud on the ammonium and nitrate concentrations, ammonia-oxidizing bacterial community and bacterial community in latosolic red soils during the incubation of microcosms was investigated. The soil nitrate concentration was significantly lower in the glucose-treated soil than in the filter mud or chicken manure-treated soil from days 2 and 5 to 21 of incubation. The ammonia-oxidizing bacteria community composition, measured by terminal restriction fragment length polymorphism analysis, was different among the treatments 9 days after incubation, suggesting that the control soil without external fertilization had a low 283-bp (Nitrosospira) fragment relative abundance (27 %) compared with the glucose-treated (62 %), filter mud (73 %) and chicken manure (78 %) samples. Additionally, 491-bp fragments (Nitrosomonas) were detected in all the soil treatments except for the control soil, and 48-bp fragments (from different Nitrosomonas) were detected in the chicken manure-treated soil. The bacterial community structure was markedly changed in the glucose-treated soil on day 9 and in the filter mud-treated soil on day 31, indicating that the effect of filter mud on the bacterial community is delayed compared to the effect of glucose. The chicken manure-treated soil showed less change, similar to that of the control soil. Glucose fertilization greatly increased the soil bacterial abundance and functional diversity; however, the chicken manure and filter mud did not stimulate soil bacterial activity on day 9. These results indicated that nitrification may have been somewhat suppressed in the glucose-treated soils, which was possibly related to the improving ammonia-oxidizing bacterial community, bacterial community and activity via the available carbon application. The filter manure and chicken manure treatments demonstrated fewer effects. These results suggest that organic carbon quality, e.g., increasing the available carbon, regulates the nitrification process and is beneficial to reducing soil nitrogen losses.  相似文献   

15.
At present, the prior-established threshold values are widely used to classify contaminated agricultural soils with heavy metals under the cultivation of a variety of crops, without considering the different sensitivity of plants to heavy metals. Evaluation of the characteristics of cadmium transfer from a polluted calcareous soil to cultivated wheat crop and assessment of the efficiency of using the threshold values to reflect the soil pollution risk by cadmium in Zanjan Zinc Town area at the northwest of Iran were the goals of this study. Totally, 65 topsoil (0–20 cm) and corresponding wheat samples of an agricultural region in the proximity of a metallurgical factory were collected and analyzed for cadmium concentration. The results revealed that industrial activities strongly control cadmium distribution in the studied soils. Relatively high bioavailable cadmium contents (mean 0.77 mg kg?1) were found in the soils, notwithstanding their alkalinity. It was observed that just 22.5% of the studied area around the Zinc Town is covered by polluted soils with the cadmium concentration exceeding the maximum permissible concentration of 5 mg kg?1, whereas cadmium concentration in wheat grains of 19 sampled plants is higher than the threshold value of 0.2 mg kg?1. Among these polluted plants, a total of eight samples were grown in areas classified as unpolluted soils with cadmium, based on the soil threshold value. It seems that this misclassification of polluted soils is mainly related to the crop sensitivity to heavy metals uptake from the soil which should be considered.  相似文献   

16.
The present study attempted to identify the efficient hazardous metal-removing sorbent from specific types of soil, upper and middle layer shirasu, shell fossil, tuff, akadama and kanuma soils of Japan by physico-chemical and metal (arsenic, cadmium and lead) removal characterizations. The physico-chemical characteristics of soil were evaluated using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy techniques, whereas metal removal properties of soil were characterized by analyzing removal capacity and sorption kinetics of potential metal-removing soils. The chemical characteristics revealed that all soils are prevalently constituted of silicon dioxide (21.83–78.58 %), aluminum oxide (4.13–38 %) and ferrous oxide (0.835–7.7 %), whereas calcium oxide showed the highest percentage (65.36 %) followed by silicon dioxide (21.83 %) in tuff soil. The results demonstrated that arsenic removal efficiency was higher in elevated aluminum oxide-containing akadama (0.00452 mg/L/g/h) and kanuma (0.00225 mg/L/g/h) soils, whereas cadmium (0.00634 mg/L/g/h) and lead (0.00693 mg/L/g/h) removal efficiencies were maximum in elevated calcium oxide-containing tuff soil. Physico-chemical sorption and ion exchange processes are the metal removal mechanisms. The critical appraisal of three metal removal data also clearly revealed cadmium > lead > arsenic order of removal efficiency in different soils, except in tuff and akadama soils followed by lead > cadmium > arsenic. It clearly signified that each type of soil had a specific metal adsorption affinity which was regulated by the specific chemical composition. It may be concluded that akadama would be potential arsenic-removing and tuff would be efficient cadmium and lead-removing soil sorbents.  相似文献   

17.
Physiological responses and metal accumulation in Vallisneria spiralis L. exposed to copper and cadmium contaminated sediment were examined at different metal concentrations and the influence of humic acids on copper and cadmium accumulation was also studied. The plants of V. spiralis accumulated high amount of copper and cadmium. The maximum accumulation of 396 and 114 mg kg−1 DW copper were found in the roots and shoots, respectively, at 614 mg kg−1 DW after 21 days’ copper exposure; they were 63.8 and 48.0 mg kg−1 DW for cadmium at 88.69 mg kg−1 DW. The plants showed decrease in chlorophyll content with the increasing concentration of copper/cadmium in sediment. With addition of humic acids from 3.09 to 7.89 g kg−1 DW, both copper and cadmium accumulation in V. spiralis were significantly inhibited (p < 0.01). The cadmium concentrations of roots and shoots of plant decreased 26.4–50.3 and 14.3–33.0% under cadmium treatments, respectively; copper accumulation decreased much more with 44.0–77.0 and 35.0–62.7%, respectively. It was concluded that V. spiralis appeared to be an ideal candidate for the phytoremediation of copper and cadmium polluted sediments, and humic acids had an important role in regulating copper and cadmium bioavailability and toxicity in sediments.  相似文献   

18.
To study the mobility of polluting agents through the soil, the authors have designed an experiment that attempts to reproduce the behavior of heavy metals in the soil as a part of the non-saturated zone. This work was based on a controlled experiment using soil columns. A calcareous soil was amended with 30,000, 90,000 and 180,000 kg sludge/ha. Chromium, cadmium, and nickel were analyzed in soil samples at intervals of 15 cm depth. Leachates were collected at the bottom of the columns and the metals were analyzed. No important displacements of polluting metals were found in this soil.  相似文献   

19.
Soil salinity and sodicity are escalating problems worldwide, especially in arid and semiarid regions. A laboratory experiment was conducted using soil column to investigate leaching of soluble cations during reclamation process of a calcareous saline–sodic soil (CaCO3?=?20.7%, electrical conductivity (EC)?=?19.8 dS m?1, sodium absorption ratio (SAR)?=?32.2[meq L?1]0.5). The amendments consisted of control, cattle manure (50 g kg?1), pistachio residue (50 g kg?1), gypsum (5.2 g kg?1; equivalent of gypsum requirement), manure + gypsum and pistachio residue + gypsum, in three replicates which were mixed thoroughly with the soil, while sulfuric acid as an amendment was added to irrigation water. To reflect natural conditions, after incubation period, an intermittent irrigation method was employed every 30 days. The results showed that EC, SAR, and soluble cations of leachate for the first irrigation step were significantly higher than those of the subsequent leaching runs. Moreover, the concentration of removed soluble cations was lower for the control and gypsum-treated soils. It was found that among applied amendments, treatments containing cattle manure showed higher concentrations of sodium, calcium, and magnesium in the leachate, while due to pistachio residue application, further amount of potassium was removed out of soil column. The addition of pistachio residue resulted in the highest reduction in soil salinity and sodicity since the final EC and exchangeable sodium percentage dropped to 18.0% and 11.6% of their respective initial values, respectively. In the calcareous soil, solubility of gypsum found to be limited, in contrast, when it was added in conjunction with organic amendments, greater amounts of sodium were leached.  相似文献   

20.
Different bacterial and fungal strains, isolated from petroleum hydrocarbon-contaminated soil, were tested, in isolation as well as in combination, for their ability to degrade total petroleum hydrocarbon (TPH) in soil samples spiked with crude oil (2, 5 or 10 %, w/w) for 30 days. The selected combination of bacterial and fungal isolates, i.e., Pseudomonas stutzeri BP10 and Aspergillus niger PS9, exhibited the highest efficiency of TPH degradation (46.7 %) in soil spiked with 2 % crude oil under control condition. Further, when this combination was applied under natural condition in soil spiked with 2 % (w/w) crude oil along with inorganic fertilizers (NPK) and different bulking agents such as rice husk, sugarcane, vermicompost or coconut coir, the percent degradation of TPH was found to be maximum (82.3 %) due to the presence of inorganic fertilizers and rice husk as bulking agent. Further, results showed that the presence of NPK and bulking agents induced the activity of degradative enzymes, such as catalase (0.718 m mol H2O2 g?1), laccase (0.77 µmol g?1), dehydrogenase (37.5 µg g?1 h?1), catechol 1, 2 dioxygenase (276.11 µ mol g?1) and catechol 2, 3 dioxygenase (15.15 µ mol g?1) as compared to control (without bioaugmentation). It was inferred that the selected combination microbes along with biostimulants could accentuate the crude oil degradation as evident from the biostimulant-induced enhanced activity of degradative enzymes.  相似文献   

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