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1.
PurposeCombining biodegradable chelating agents with phytoextraction is an efficient technique to amend metal-contaminated soils, but most studies have addressed remediation efficiency rather than a comprehensive understanding of the interactions among plant stress, metal accumulation, and metal bioavailability. This study aimed to investigate the effects of biodegradable chelating agents on improving the efficiency of phytoextraction for cobalt (Co)-contaminated soil by sweet alyssum (Lobularia maritima (L.)) and to explore the interrelationships among plant stress, Co accumulation, and Co bioavailability. Materials and methodsSweet alyssum (three plants per pot) was grown in pots containing soil with Co added at 0, 40, and 60 mg kg?1, respectively. After 70 days of growth, we added four biodegradable chelating agents (EDDS, NTA, CA, and OA) at various concentrations (0, 2.5, 5.0, and 7.5 mmol kg?1). The plants were harvested after 7 days, and the biomass, reactive oxygen species (ROS) parameters, Co concentrations of the shoot and root, and available Co content in the soil were analyzed. Results and discussionThe results demonstrate that chelating agents significantly (p?<?0.05) improved the phytoextraction capability of sweet alyssum and influenced plant growth and stress. The capability of EDDS to activate Co was higher than that of other chelating agents at identical concentrations in Co-contaminated soils. Furthermore, we observed that a moderate concentration (40 mg kg?1) of Co could promote plant growth and that high concentrations of Co (60 mg kg?1) and EDDS (7.5 mmol kg?1) cause enhanced stress to plant growth, even resulting in lower shoot Co accumulation than that in the moderate EDDS treatment (5.0 mmol kg?1). ConclusionsThe present study demonstrates that the application of EDDS may be a better choice for Co phytoextraction than NTA, CA, and OA; nevertheless, a high concentration of EDDS may enhance the negative effects on plant growth, physiological traits, and Co accumulation. 相似文献
2.
Purpose The effects of the addition of an acidic fertilizer solution and/or slaked lime (5.5 g Ca(OH) 2 kg −1) on a slightly acidic shooting range soil (pH 6.1, % organic carbon 5.4) with moderate metal (e.g., 620 mg kg −1 Pb) and metalloid (17 mg kg −1 Sb) concentrations on metal and Sb solubility and plant accumulation were investigated. 相似文献
3.
The following six pig slurries obtained after acidification and/or solid/liquid separation were used in the research: original
(S) and acidified (AS) pig slurry, nonacidified (LF) and acidified (ALF) pig slurry liquid fraction, and nonacidified (SF)
and acidified (ASF) pig slurry solid fraction. Laboratory incubations were performed to assess the effect of the application
of these slurries on N mineralization and CO 2 and N 2O emissions from a sandy soil. Acidification maintained higher NH 4
+-N contents in soil particularly in the ALF-treated soil where NH 4
+-N contents were two times higher than in LF-treated soil during the 55–171-day interval. At the end of the incubation (171 days),
32.9 and 24.2 mg N kg −1 dry soil were mineralized in the ASF- and SF-treated soils, respectively, but no mineralization occurred in LF- and S-treated
soils, although acidification decreased N immobilization in ALF- (−25.3 mg N kg −1 soil) and AS- (−12.7 mg N kg −1 soil) compared to LF- (−34.4 mg N kg −1 soil) and S-treated (−18.6 mg N kg −1 soil) soils, respectively. Most of the dissolved CO 2 was lost during the acidification process. More than 90% of the applied C in the LF-treated soil was lost during the incubation,
indicating a high availability of the added organic compounds. Nitrous oxide emissions occurred only after day 12 and at a
lower rate in soils treated with acidified than nonacidified slurries. However, during the first 61 days of incubation, 1,157 μg N
kg −1 soil was lost as N 2O in the AS-treated soil and only 937 in the S-treated soil. 相似文献
4.
Red lead (Pb 3O 4) has been used extensively in the past as an anti-corrosion paint for the protection of steel constructions. Prominent examples
being some of the 200,000 high-voltage pylons in Germany which have been treated with red lead anti-corrosion paints until
about 1970. Through weathering and maintenance work, paint compounds and particles are deposited on the soils beneath these
constructions. In the present study, six such “pylon soils” were investigated in order to characterize the plant availability
and plant uptake of Pb, Cd, and Zn. For comparison, three urban soils with similar levels of heavy metal contamination were
included. One phase extractions with 1 M NH 4NO 3, sequential extractions (seven steps), and extractions at different soil pH were used to evaluate the heavy metal binding
forms in the soil and availability to plants. Greenhouse experiments were conducted to determine heavy metal uptake by Lolium multiflorum and Lactuca sativa var. crispa in untreated and limed red lead paint contaminated soils. Concentrations of Pb and Zn in the pylon soils were elevated with
maximum values of 783 mg Pb kg −1 and 635 Zn mg kg −1 while the soil Cd content was similar to nearby reference soils. The pylon soils were characterized by exceptionally high
proportions of NH 4NO 3-extractable Pb reaching up to 17% of total Pb. Even if the relatively low pH of the soils is considered (pH 4.3–4.9), this
appears to be a specific feature of the red lead contamination since similarly contaminated urban soils have to be acidified
to pH 2.5 to achieve a similarly high Pb extractability. The Pb content in L. multiflorum shoots reached maximum values of 73 mg kg −1 after a cultivation time of 4 weeks in pylon soil. Lime amendment reduced the plant uptake of Pb and Zn significantly by
up to 91%. But L. sativa var. crispa cultivated on soils limed to neutral pH still contained critical Pb concentrations (up to 0.6 mg kg −1 fresh weight). Possible mechanisms for the exceptionally high plant availability of soil Pb derived from red lead paint are
discussed. 相似文献
5.
Modern agricultural systems have to provide enough micronutrient output to meet all the nutritional needs of people. Accordingly,
knowledge on micronutrient status in soil and crop edible tissues is necessary. This study was carried out to investigate
zinc (Zn), iron (Fe), manganese (Mn), and copper (Cu) concentration of calcareous paddy soil and the relative rice grain.
Rice crops (straw, hull, and grain) and associated surface soils (0–25 cm) were collected from 136 fields and analyzed for
total and diethylene triamine pentaacetic acid (DTPA) available Zn, Fe, Mn, and Cu. The DTPA-Zn concentration in more than
50% of paddy soils was less than its critical deficiency concentration (2 mg kg −1), while the concentrations of DTPA Fe, Mn, and Cu were sufficient. The grain Zn concentration of more than 54% of the rice
samples was less than 20 mg kg −1. About 55% and 49% of the rice samples were deficient in Mn and Cu, respectively, while the Fe concentration in rice grains
was sufficient. A significant negative correlation was found between the CaCO 3 content and soil DTPA-extractable Zn, Fe, Mn, and Cu. There were significant relationships between the total soil phosphorus
and DTPA-extractable micronutrient concentrations. By considering the average daily rice consumption of 110 g per capita,
the Zn, Fe, Mn, and Cu intake from rice consumption was estimated to be 2.4, 7.7, 1.6, and 0.7 mg for adults, respectively. 相似文献
6.
The aim of this greenhouse experiment was the assessment of the influence of H 2SeO 3 at soil concentrations of 0.05, 0.15 and 0.45 mmol kg −1, on the activity of selected oxidoreductive enzymes in wheat ( Triticum aestivum). The wheat plants were grown in 2 dm 3 pots filled with dust-silt black soil of pH 7.7. Applied H 2SeO 3 caused activation of plant nitrate reductase at all concentrations, but activation of plant polyphenol oxidase at only two lower concentrations. The highest concentration caused inhibition of polyphenol oxidase and peroxidase. Plant catalase activity decreased under the influence of 0.15 and 0.45 mmol kg −1 concentration. After the final analysis Se was quantified in plants and soil. The amounts in plants were: control (unamended soil) 1.95 mg kg −1; I dose (0.05 mmol kg −1) 18.27 mg kg −1; II dose (0.15 mmol kg −1) 33.20 mg kg −1 and III dose (0.45 mmol kg −1) 38.37 mg kg −1, in soil: 0.265 mg kg −1; 3.61 mg kg −1; 10.53 mg kg −1; 30.53 mg kg −1; respectively. Simultaneously, a laboratory experiment was performed, where the activity of soil catalase and peroxidase were tested after 1, 3, 7, 14, 28, 56, and 112 days after Se treatment. Peroxidase activity in soil decreased with increasing Se content, over the whole experiment. The lowest dose of Se caused activation a significant 10% increase in catalase activity, but the influence of others doses was unclear. 相似文献
7.
Incidental losses of dissolved reactive phosphorus (DRP) to a surface waterbody originate from direct losses during land application
of fertilizer, or where a rainfall event occurs immediately thereafter. Another source is the soil. One way of immobilising
DRP in runoff before discharge to a surface waterbody, is to amend soil within the edge of field area with a high phosphorus
(P) sequestration material. One such amendment is iron ochre, a by-product of acid mine drainage. Batch experiments utilising
two grassland soils at two depths (topsoil and sub-soil), six ochre amendment rates (0, 0.15, 1.5, 7.5, 15 and 30 g kg −1 mass per dry weight of soil) and five P concentrations (0, 5, 10, 20 and 40 mg L −1) were carried out. A proportional equation, which incorporated P sources and losses, was developed and used to form a statistical
model. Back calculation identified optimal rates of ochre amendment to soil to ameliorate a specific DRP concentration in
runoff. Ochre amendment of soils (with no further P inputs) was effective at decreasing DRP concentrations to acceptable levels.
A rate of 30 g ochre kg −1 soil was needed to decrease DRP concentrations to acceptable levels for P inputs of ≤10 mg L −1, which represents the vast majority of cases in grassland runoff experiments. However, although very quick and sustained
metal release above environmental limits occurred, which makes it unfeasible for use as a soil amendment to control P release
to a waterbody, the methodology developed within this paper may be used to test the effectiveness and feasibility of other
amendments. 相似文献
8.
This work aims to identify and characterize heavy metal contamination in a fluvial system from Cartagena–La Unión mining district
(SE Spain). In order to assess the dynamics of transport and the accumulation of heavy metals, sediments, surface water and
vegetation, samples along “El Avenque” stream were collected. The former direct dumps of wastes and the presence of tailing
ponds adjacent to the watercourse have contributed to the total contamination of the stream. Total Cd (103 mg kg −1), Cu (259 mg kg −1), Pb (26,786 mg kg −1) and Zn (9,312 mg kg −1) in sediments were above the limits of European legislation, being highest where tailing ponds are located. Bioavailable
metals were high (3.55 mg Cd kg −1, 6.45 mg Cu kg −1, 4,200 mg Pb kg −1 and 343 mg Zn kg −1) and followed the same trend than total contents. Metals in water were higher in sampling points close to ponds, exceeding
World Health Organization guidelines for water quality. There is a direct effect of solubilisation of sediment metals in water
with high contents of SO 42−, product of the oxidation of original sulphides. The mobility of metals varied significantly with shifts in pH. Downstream,
available and soluble metals concentrations decreased mainly due to precipitation by increments in pH. As a general pattern,
no metal was bioaccumulated by any tested plant. Thus, native vegetation has adopted physiological mechanisms not to accumulate
metals. This information allows the understanding of the effect of mining activities on stream contamination, enforcing the
immediate intervention to reduce risks related to metals’ mobility. 相似文献
9.
Fixed NH 4+ (NH 4+
f) and fixation and defixation of NH 4+ in soils have been the subject of a number of investigations with conflicting results. The results vary because of differences
in methodology, soil type, mineralogical composition, and agro-climatic conditions. Most investigators have determined NH 4+
f using strong oxidizing agents (KOBr or KOH) to remove organic N and the remaining NH 4+
f does not necessarily reflect the fraction that is truly available to plants. The content of native NH 4+
f in different soils is related to parent material, texture, clay content, clay mineral composition, potassium status of the
soil and K saturation of the interlayers of 2:1 clay minerals, and moisture conditions. Evaluation of the literature shows
that the NH 4+
f-N content amounts to 10–90 mg kg −1 in coarse-textured soils (e.g., diluvial sand, red sandstone, granite), 60–270 mg kg −1 in medium-textured soils (loess, marsh, alluvial sediment, basalt) and 90–460 mg kg −1 in fine-textured soils (limestone, clay stone). Variable results on plant availability of NH 4+
f are mainly due to the fact that some investigators distinguished between native and recently fixed NH 4+ while others did not. Recently fixed NH 4+ is available to plants to a greater degree than the native NH 4+
f, and soil microflora play an important role in the defixation process. The temporal changes in the content of recently fixed
NH 4+ suggest that it is actively involved in N dynamics during a crop growth season. The amounts of NH 4+ defixed during a growing season varied greatly within the groups of silty (20–200 kg NH 4+-N ha −1 30 cm −1) as well as clayey (40–188 kg NH 4+-N ha −1 30 cm −1) soils. The pool of recently fixed NH 4+ may therefore be considered in fertilizer management programs for increasing N use efficiency and reducing N losses from
soils. 相似文献
10.
Purpose The purpose of the present study was to investigate the composition and structure of microbial communities in rhizosphere
soils in response to the presence of Aroclor 1242 with low (8 mg kg −1 soil) and high (16 mg kg −1 soil) concentrations in the hope to provide more information on potential dissipation of polychlorinated biphenyls (PCBs)
at contaminated sites. 相似文献
11.
Background, Aims and Scope Phytoremediation is a promising means for the treatment of heavy metal contamination. Although several species have been identified
as hyperaccumulators, most studies have been conducted with only one metal. Experiments were conducted to investigate the
ability of Helianthus annuus and Thlaspi caerulescens to simultaneously uptake Cd, Cr and Ni.
Materials and Methods The efficiency of plants grown in a sandy-loam soil was investigated. The ability of two EDTA concentrations (0.1 and 0.3
g kg −1) for enhancing the phytoremediation of Cd, Cr and Ni at two different metal concentrations (24.75 mg kg −1 and 90 mg kg −1) was studied.
Results
Thlaspi hyperaccumulated Ni with 0.1 g kg −1 EDTA. When the EDTA dosage was increased to 0.3 g kg −1, Thlaspi was able to hyperaccumulate both Ni and Cr. Since Thlaspi is a low-biomass plant, it was considered insufficient for full-scale applications. Helianthus annuus hyperacummulated Cr (with 0.1 g kg −1 EDTA) and Cd (0.3 g kg −1 EDTA).
Discussion When the contamination was 8.25 mg kg −1 per metal, the total metal uptake was 10–25% (1.35 to 2.12 mg) higher and had the same uptake selectivity (Cr>>Cd>Ni) for
both EDTA levels. It was hypothesized that complexation with EDTA interfered with Ni translocation. For these experiments,
the optimal results were obtained with the H. annuus-0.1 g kg −1 EDTA combination.
Conclusions Although the use of EDTA did increase the amount of metal that could be extracted, care should be taken during in-situ field
applications. Chelators can also increase the amount of metals that are leached past the root zone. Metal leaching and subsequent
migration could lead to ground water contamination as well as lead to new soil contamination.
Recommendations and Perspectives Additional research to identify the optimal EDTA dosage for field applications is warranted. This is necessary to ensure that
the metals do not leach past the root zone.
Identification of a plant that can hyperaccumulate multiple metals is critical for phytoremediation to be a viable remediation
alternative. In addition to being able to hyperaccumulate multiple metals, the optimal plant must be fast growing with sufficient
biomass to sequester the heavy metals. 相似文献
12.
During the intensive flood in May–June 2010, the floodplains in Little Poland Vistula Gap, used mostly for agriculture, were
waterlogged for a period of over 1 month. The aim of the study was to assess the effect of the flood on the level of contamination
of the soils in this region. The analysis included basic physicochemical soil properties, contents of ten metals, and concentrations
of 16 polycyclic aromatic hydrocarbons (PAHs). The studies cover two territories on opposite sites of the river Vistula (Wilkow
and Janowiec) differing in their areas (70 and 4.6 km 2) and time of water logging (30 and 10 days). Forty soil samples were collected from both areas immediately after the flood
event from the upper (0–30 cm) soil layer together with four samples from the 30–60-cm depth layer. This was supplemented
by eight samples from the flood-deposited sediment layer (thickness, 2 cm). The concentrations of identified metals (As, Ba,
Cr, Sn, Zn, Cd, Co, Cu, Ni, Pb) at all the sampling points were below the Polish legal limits for the upper layer of soils
for agriculture use. The same regarded the median contents of nine PAHs compounds specified in the Polish regulations. In
both areas, the median contents of Σ16 PAHs (0.21–0.35 mg kg −1), Zn (10.3–10.6 mg kg −1), Pb (9.2–10.7 mg kg −1), and Cd (0.03 mg kg −1) were much below the mean concentrations of those contaminants in arable soils on the national and European levels. The results
show that this severe flooding episode in “clean” agricultural area had no immediate negative impact on the soils as regards
the basic physicochemical properties (organic matter content, acidity, nitrogen content) and did not result in excessive soil
contamination. 相似文献
13.
The effect of reduced tillage (RT) on nitrous oxide (N 2O) emissions of soils from fields with root crops under a temperate climate was studied. Three silt loam fields under RT agriculture
were compared with their respective conventional tillage (CT) field with comparable crop rotation and manure application.
Undisturbed soil samples taken in September 2005 and February 2006 were incubated under laboratory conditions for 10 days.
The N 2O emission of soils taken in September 2005 varied from 50 to 1,095 μg N kg −1 dry soil. The N 2O emissions of soils from the RT fields taken in September 2005 were statistically ( P < 0.05) higher or comparable than the N 2O emissions from their respective CT soil. The N 2O emission of soils taken in February 2006 varied from 0 to 233 μg N kg −1 dry soil. The N 2O emissions of soils from the RT fields taken in February 2006 tended to be higher than the N 2O emissions from their respective CT soil. A positive and significant Pearson correlation of the N 2O–N emissions with nitrate nitrogen (NO 3
−–N) content in the soil was found ( P < 0.01). Leaving the straw on the field, a typical feature of RT, decreased NO 3
−–N content of the soil and reduced N 2O emissions from RT soils. 相似文献
14.
Crop residues with high C/N ratio immobilize N released during decomposition in soil, thus reducing N losses through leaching,
denitrification, and nitrous oxide (N 2O) emission. A laboratory incubation experiment was conducted for 84 days under controlled conditions (24°C and moisture content
55% of water-holding capacity) to study the influence of sugarcane, maize, sorghum, cotton and lucerne residues, and mineral
N addition, on N mineralization–immobilization and N 2O emission. Residues were added at the rate of 3 t C ha −1 to soil with, and without, 150 kg urea N ha −1. The addition of sugarcane, maize, and sorghum residues without N fertilizer resulted in a significant immobilization of
soil N. Amended soil had significantly ( P < 0.05) lower NO 3−–N, which reached minimum values of 2.8 mg N kg −1 for sugarcane (at day 28), 10.3 mg N kg −1 for maize (day 7), and 5.9 mg N kg −1 for sorghum (day 7), compared to 22.7 mg N kg −1 for the unamended soil (day 7). During 84 days of incubation, the total mineral N in the residues + N treatments were decreased
by 45 mg N kg −1 in sugarcane, 34 mg kg −1 in maize, 29 mg kg −1 in sorghum, and 16 mg kg −1 in cotton amended soil compared to soil + N fertilizer, although soil NO 3−–N increased by 7 mg kg −1 in lucerne amended soil. The addition of residues also significantly increased amended soil microbial biomass C and N. Maximum
emissions of N 2O from crop residue amended soils occurred in the first 4–5 days of incubation. Overall, after 84 days of incubation, the
cumulative N 2O emission was 25% lower with cotton + N fertilizer, compared to soil + N fertilizer. The cumulative N 2O emission was significantly and positively correlated with NO 3−–N ( r = 0.92, P < 0.01) and total mineral N ( r = 0.93, P < 0.01) after 84 days of incubation, and had a weak but significant positive correlation with cumulative CO 2 in the first 3 and 5 days of incubation ( r = 0.59, P < 0.05). 相似文献
15.
A greenhouse experiment was conducted in a red sandy loam soil (Alfisol) to study the responses of arbuscular mycorrhizal
(AM) fungus Glomus intraradices Schenck & Smith inoculated (M+) and uninoculated (M−) maize ( Zea mays L) plants exposed to various levels of P (15 and 30 mg kg −1) and Zn (0, 1.25, and 2.5 mg kg −1). Roots and shoots were sampled at 55 and 75 days after sowing and assessed for their nutritional status, root morphology,
and root cation exchange capacity (CEC) besides grain quality. Mycorrhizal plants had longer and more extensive root systems
than nonmycorrhizal plants, indicating that M+ plants are nutritionally rich, especially with P, which directly assisted in
the proliferation of roots. Further, root CEC of M+ plants were consistently higher than those of M− plants, suggesting that
mycorrhizal colonization assists in the acquisition of nutrients from soil solution. Mycorrhizal inoculated plants had significantly
( P ≤ 0.01) higher P and Zn concentrations in roots, shoots, and grains, regardless of P or Zn levels. The available Zn and P
status of AM fungus-inoculated soils were higher than unioculated soils. The data suggest that mycorrhizal symbiosis improves
root morphology and CEC and nutritional status of maize plants by orchestrating the synergistic interaction between Zn and
P besides enhancing soil available nutrient status that enables the host plant to sustain zinc-deficient conditions. 相似文献
16.
The co-application of glufosinate with nitrogen fertilizers may alter atrazine cometabolism, thereby extending the herbicide’s
residual weed control in adapted soils. The objective of this study was to assess the effects of glufosinate, ammonium sulfate,
and the combination of glufosinate and ammonium sulfate on atrazine mineralization in a Dundee silt loam exhibiting enhanced
atrazine degradation. Application of glufosinate at rates of 10 to 40 mg kg −1 soil extended the lag phase 1 to 2 days and reduced the maximum degradation rate by 15% to 30%. However, cumulative atrazine
mineralization averaged 85% 21 days after treatment and was independent of treatment. Maximum daily rates of atrazine mineralization
were reduced from 41% to 55% by application of 1 to 8 g kg −1 of ammonium sulfate. Similarly, cumulative atrazine mineralization was inversely correlated with ammonium sulfate rates ranging
from 1.0 to 8 g kg −1 soil. Under the conditions of this laboratory study, atrazine degradation was relatively insensitive to exogenous mineral
nitrogen, in that 8 g (NH 4) 2SO 4 per kilogram soil repressed but did not completely inhibit atrazine mineralization. Moreover, an additive effect on reducing
atrazine mineralization was observed when glufosinate was co-applied with ammonium sulfate. In addition, ammonium fertilization
alters the partitioning of 14C-atrazine metabolite accumulation and nonextractable residues, indicating that ammonium represses cleavage of the triazine
ring. Consequently, results indicate that the co-application of glufosinate with N may increase atrazine persistence under
field conditions thereby extending atrazine residual weed control in adapted soils. 相似文献
17.
The abandonment of cultivated wetland soil increased the contents of light fraction organic matter (LFOM), heavy fraction
organic matter (HFOM) and soil organic matter (SOM). The LFOM and HFOM content increased to 13.3 g kg −1 and 62.4 g kg −1 after 5 years whereas they were 8.4 and 47.9 g kg −1 after 9 years of cropping, respectively. Fourteen years after abandonment, HFOM content increased to 104.3 g kg −1. LFOM was positively correlated with HFOM ( p < 0.001). A Langmuir equation was used to calculate the highest HFOM value. The value for the natural wetland soil was closed
to this theoretical value (140.8 g kg −1). After 14 years of abandonment, the HFOM maximum (HFOM Max) value was lower than the equilibrium value suggesting that a further increase in HFOM can occur after abandonment. Assuming
a linear accumulation (3.87 Mg C ha −1yr −1), it would take approximately 24 years after the abandonment to reach the HFOM Max value. 相似文献
18.
Surface sediments (0–5 cm) were analysed to provide information on levels, spatial trends and sources of the 16 USEPA polycyclic
aromatic hydrocarbons (PAH), 15 polychlorinated biphenyls (PCBs) and trace metals (copper, chromium, mercury, nickel and zinc)
in channel and wetland habitats of Pialassa Baiona lagoon (Italy). The highest levels of PAHs, PCBs and Hg (3,032–87,150,
n.d.–3,908 and 1.3–191 mg kg −1) were mainly found at channel habitats close to industrial sources. Pyrogenic PAH inputs were significant, with a predominance
of four-ring PAHs and combustion-related PAHs in both channel and wetland habitats. Among PCB congeners, chlorination class
profiles show that penta- and hexachlorinated PCBs are the most prevalent homologues accounting for approximately 33% and
47% of the total PCB concentrations in channel sediments. Total toxicity equivalent factors (TEQs) of potentially carcinogenic
PAHs varied from 348 to 7,879 μg kg −1 and from 4.3 to 235 μg kg −1 in channel and wetland sediments; calculated TEQs for dioxin-like PCB congeners at channel habitats ranged from n.d. to 86.7 μg kg −1. Comparison of PAHs, PCBs and metal levels with Sediment Quality Guidelines suggests that more concern should be given to
the southern area of the lagoon for potential risks of carcinogenic PAHs, dioxin-like PCBs and mercury. 相似文献
19.
Two pot experiments were conducted to investigate the effect of inoculation with the arbuscular mycorrhizal (AM) fungus Glomus intraradices on Pb uptake by two clones of Nicotiana tabacum plants. Non-transgenic tobacco plants, variety Wisconsin 38, were compared in terms of Pb uptake with transgenic plants of the same variety with inserted gene coding for polyhistidine anchor in fusion with yeast metallothionein. Bioavailability of Pb in experimentally contaminated soil was enhanced by the application of a biodegradable chelate ethylenediaminedissuccinate (EDDS).EDDS addition (2.5 and 5.0 mmol kg −1 substrate) increased Pb uptake from the substrate and enhanced Pb translocation from the roots to the shoots, with shoot Pb concentrations reaching up to 800 mg kg −1 at the higher chelate dose. Application of a single dose of 5 mmol kg −1 proved to be more efficient at increasing shoot Pb concentrations than two successive doses of 2.5 mmol kg −1, in spite of a marked negative effect on plant growth and phytotoxicity symptoms. Pb amendment (1.4 g kg −1 substrate) connected with either dose of EDDS decreased significantly plant biomass as well as reduced the development of AM fungi. AM inoculation promoted the growth of tobacco plants and partly alleviated the negative effect of Pb contamination, mainly in the case of root biomass.No consistent difference in Pb uptake was found between transgenic and non-transgenic tobacco plants. The effect of AM inoculation on Pb concentrations in plant biomass varied between experiments, with no effect observed in the first experiment and significantly higher root Pb concentrations and increased root–shoot ratio of Pb concentrations in the biomass of inoculated plants in the second experiment. Due to probable retention of Pb in fungal mycelium, the potential of AM for phytoremediation resides rather in Pb stabilisation than in phytoextraction. 相似文献
20.
Six chelating compounds: ethylenediamine-tetraacetic acid (EDTA), ethylenediamine-N, N'-disuccinic acid (EDDS), tartaric acid, citric acid, glycine and histidine, were tested as potential agents to mobilize copper (Cu) and lead (Pb) from two soils polluted with the emissions from copper smelters. Copper was mobilized with the following efficiency: EDTA > citric and tartaric acids > histidine > EDDS and glycine, while Pb extractability followed the order: EDTA > EDDS >> tartaric and citric acid >> glycine and histidine. With respect to these results, EDTA and EDDS were chosen for a pot experiment on chelate-induced phytoextraction of Cu and Pb by maize (Zea mays). Chelates were applied at the rates of 0.2, 0.5, and 1.0 mmol kg ?1, and this experiment was carried out at two different watering regimes. Both EDTA and EDDS caused significant increase of Cu uptake from soils, but its concentrations in biomass were far below those required for efficient soil remediation. Lead uptake was only slightly affected by chelate application. Losses of Cu from soil by leaching were much higher than those caused by plant uptake. 相似文献
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