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1.
Jean-Philippe Bedell Xavier Capilla Claire Giry Christophe Schwartz Jean-Louis Morel Yves Perrodin 《Environmental and Experimental Botany》2009,67(2):403-414
Willows occur as volunteer vegetation on sediment-derived soils, such as dredged sediments, landfill cover or stockpile deposits, and are used as phytoremediators on such soils. The present study evaluates growth and metal uptake by Salix alba grown on a contaminated dredge sediment for 209 days under greenhouse conditions. At the end of the study, the aerial parts of the S. alba plants had grown to heights of between 80 and 117 cm. Biomass and Cd and Zn concentration in the roots, stems and leaves, at 70, 112 and 209 days, showed that Cd and Zn had been bioaccumulated, especially in the leaves.At the three sampling dates, Cd and Zn extractability and pH measurements were also carried out on samples of two soil layers (0–15 and 15–30 cm) from both the planted and the control pots. Cd and Zn extractability were assessed using single extraction procedures (0.01 M CaCl2; 1 M HNO3; CaCl2–TEA–DTPA). The two metals showed similar variations in CaCl2 and HNO3 extractabilities, but this was not the case for DTPA extractability. The greatest variations were observed in the upper soil layers of the control pots. In the planted pots, the CaCl2 extractability of Zn decreased in the upper layer, and the HNO3 extractability of Zn increased in the lower layer. The pH of the upper soil layer was always higher than the pH of the bottom layer. In addition, we monitored several parameters of the percolates from both the planted and the control sediments, including pH, Eh, conductivity, dissolved organic carbon, Zn and Cd concentrations, and presence of certain cations/anions. Dissolved organic carbon, and Cd and Zn concentrations increased steadily over time. There were no significant differences between the planted and the control pots. After 209 days, the characteristics of the control sediment reflected the effects of ageing in that the CaCl2-extractable Cd and Zn concentrations had decreased compared with the initial concentrations. Conversely, the concentrations of HNO3-extractable Cd and Zn had increased. A fraction of the metal initially extracted by CaCl2 (considered as exchangeable) became less available with time. After 112 days, the plants had extracted approximately 2.8 mg of Zn. At the same time, the CaCl2 extractability of Zn in the upper, rooted layer decreased by 2.6 mg. We can assume that S. alba extracted Zn from the pool of CaCl2-extractable Zn. 相似文献
2.
Cyanobacterial akinete induction and its application as biofertilizer for rice cultivation 总被引:1,自引:0,他引:1
Sasidhorn Innok Somporn Chunleuchanon Nantakorn Boonkerd Neung Teaumroong 《Journal of applied phycology》2009,21(6):737-744
Nostoc sp. VICCR1-1 was induced in order to form akinetes on the basis of nutrient modification. Phosphorus and iron were found
to be the critical for akinete differentiation, especially when both elements were omitted. The number of akinete cells increased
up to 20% when compared with culturing in BG110 medium (without N source). In addition, CaCl2 played a role in heterocyst differentiation, and was able to induce heterocyst ranging between 30% and 46%. In order to prepare
akinetes as inoculum, the dried form of akinetes was prepared by mixing it with montmorillonite clay. The inoculum with the
amount of 2.8 × 106 cells m−2 was applied to rice (Oryza sativa) fields. After harvesting, the grain yields from chemical N fertilizer, vegetative cells, and akinete inoculum treatments
were not significantly different. To monitor the persistence of Nostoc sp. VICCR1-1 after harvesting, the most probable number-denaturing gradient gel electrophoresis technique using 16S rRNA
gene was employed. The results indicated that the remaining population is at 2.5 × 105 and 1.62 × 106 cells m−2 in treatments supplied with vegetative cells and akinete inocula, respectively. Akinete induction might be one of the appropriate
approaches for producing cyanobacterial inoculum. 相似文献
3.
The mobility of heavy metals in contaminated soils is dependent on the kinetics release from soils. Metal extraction over time is commonly used to distinguish two or more fractions of metal based on differences of extraction or release rates. Kinetic studies using 0.01 M CaCl2, 0.01 M malic acid, and 0.01 M EDTA extractions were performed to characterize nickel (Ni) and lead (Pb) kinetic release in 10 contaminated calcareous soils. Proportions of Ni and Pb extracted with EDTA were higher than when using malic acid and CaCl2, respectively. The release of Ni and Pb was characterized by an initial fast rate followed by a slower rate and could best be described by a two first-order reactions model with rate constants k1 and k2 and two metal pools: readily labile (Q 1) and less labile (Q 2). In an EDTA extractant, different Q1 /Q2 ratios for Ni and Pb were observed, indicating binding energies to soil constituents is not comparable. The k1 of the model for Ni (average of 10 soils: 0.2204 h?1 and 0.2359 h?1 for 0.01 M CaCl2 and 0.01 EDTA, respectively) was higher than Pb (0.1044 h?1 and 0.1631 h?1 for 0.01 M CaCl2 and 0.01 M EDTA, respectively), indicating a higher potential of Ni for leaching and groundwater contamination in contaminated calcareous soils. Relationships between the fraction of Ni and Pb determined with the two first-order reactions model and the soil composition and Pb fractions were established. The results indicated that the efficiency of the extractions Ni and Pb from soils depends both on the Ni and Pb content and soil composition. Overall, the results indicated that the use of a 0.01 M malic acid washing solution would be preferred in the field condition. 相似文献
4.
The relative exclusion of zinc and iron from rice grain in relation to rice grain cadmium as compared to soybean: Implications for human health 总被引:12,自引:1,他引:11
R W. Simmons P. Pongsakul R. L. Chaney D. Saiyasitpanich S. Klinphoklap W. Nobuntou 《Plant and Soil》2003,257(1):163-170
During 2000–2002, diagnostic rice and soybean plant samples and concurrent soil samples were collected from cultivated fields within a geo-physically unique Zn/Cd co-contaminated location in Thailand. For the fields sampled, aqua regia-digested Zn and Cd concentrations ranged from 2.91–284 and 254–8036 mg kg–1, respectively. In comparison, rice and soybean Cd concentrations ranged from 0.02–5.00 and 1.08–1.71 mg kg–1, respectively. Further, the results indicate that grain Cd, Zn and Fe concentrations are in the order riceGr=soybeanGr, soybeanGr>riceGr, soybeanGr>riceGr, respectively. However, and critically from a human health perspective, Cd:Zn and Cd:Fe ratios are in the order riceGr>soybeanGr. In addition, the riceGr Cd:Fe ratio is an order of magnitude higher than that determined for soybeanGr. The results of this study, clearly demonstrate that compared to rice stalk (riceSt) and rice leaf (riceL), riceGr accumulates comparatively higher Cd than Zn and Fe thus resulting in the high riceGr Cd:Zn and Cd:Fe ratios. This is in direct contrast to the results observed for soybean. 相似文献
5.
Screening and characterization of bioflocculant produced by isolated Klebsiella sp. 总被引:18,自引:0,他引:18
Sixteen strains of polymer-producing bacteria were isolated from the activated sludge samples taken from two seafood processing
plants in Southern Thailand. Their culture broths possessed the ability to flocculate kaolin suspension in the presence of
1% CaCl2. Based on the flocculating activity, the strain S11 was selected and identified to be a Klebsiella sp. using the partial 16S rRNA sequencing method. The growth of the isolated Klebsiella sp. was maximal (1.026 g l−1 dry cell mass) after 1 day cultivation while the highest polymer yield (0.973 g l−1) was achieved after 5 days cultivation. The flocculating activity of the culture broth, however, was highest after 2 days
cultivation. The polymer was identified to be an acidic polysaccharide containing neutral sugar and uronic acid as its major
and minor components, respectively. Results on the properties of the partially purified polysaccharide from Klebsiella sp. S11 revealed that it consisted of galactose, glucose and mannose in an approximate ratio of 5:2:1. It was soluble in
acidic or basic solutions but not in organic solvents. Its molecular mass was greater than 2 × 106 Da. Infrared spectra showed the presence of hydroxyl, carboxyl and methoxyl groups in its molecules. Differential scanning
calorimetry of the polysaccharide indicated the crystalline melting point (T
m) at 314 °C. The optimum dosage of polysaccharide to give the highest flocculating activity was 15 mg l−1 in the presence of 1% CaCl2.
Received: 8 February 1999 / Received last revision: 4 June 1999 / Accepted: 4 June 1999 相似文献
6.
Dissolved organic matter in poultry litter could contribute organic ligands to form complexes with heavy metals in soil. The soluble complexes with heavy metals can be transported downward and possibly deteriorate groundwater quality. To better understand metal mobilization by soluble organic ligands in poultry litter, soil columns were employed to investigate the movement of zinc (Zn), cadmium (Cd), and lead (Pb). Uncontaminated soil was amended with Zn, Cd, and Pb at rates of 400, 8, and 200 mg kg ? 1 soil, respectively. Glass tubes, 4.9-cm-diameter and 40-cm-long, were packed with either natural or metal-amended soil. The resulting 20-cm-long column of soils had bulk density of about 1.58 g cm ? 3 . Columns repacked with natural or amended soil were leached with distilled water, 0.01 M EDTA, 0.01 M CaCl 2 , or poultry litter extract (PLE) solutions. Low amounts of Zn, Cd, and Pb were leached from natural soil with the solutions. Leaching of Zn, Cd, or Pb was negligible with distilled water. In the metal-amended soil, EDTA solubilized more Zn, Cd, and Pb than CaCl 2 and PLE. The breakthrough curves of Zn and Pb in the PLE and CaCl 2 were similar, indicating they have similar ability to displace Zn and Pb from soils. Compared with Zn and Cd the PLE had a small ability to solubilize Pb from metal-amended soil. Thus, the application of poultry litter on metal-contaminated soils might enhance the mobility of Zn and Cd. 相似文献
7.
Leaf chlorosis in oilseed rape plants (Brassica napus) grown on cadmium-polluted soil: causes and consequences for photosynthesis and growth 总被引:11,自引:0,他引:11
Brassica napus L. (oilseed rape) was grown from seeds on a reconstituted soil contaminated with cadmium (100 mg Cd kg−1 dry soil), resulting in a marked chlorosis of the leaves which was investigated using a combination of biochemical, biophysical
and physiological methods. Spectroscopic and chromatographic analyses of the photosynthetic pigments indicated that chlorosis
was not due to a direct interaction of Cd with the chlorophyll biosynthesis pathway. In addition, mineral deficiency and oxidative
stress were apparently not involved in the pigment loss. Leaf chlorosis was attributable to a marked decrease in the chloroplast
density caused by a reduction in the number of chloroplasts per cell and a change in cell size, suggesting that Cd interfered
with chloroplast replication and cell division. Relatively little Cd was found in the chloroplasts and the properties of the
photosynthetic apparatus (electron transport, protein composition, chlorophyll antenna size, chloroplast ultrastructure) were
not affected appreciably in plants grown on Cd-polluted soil. Depth profiling of photosynthetic pigments by phase-resolved
photoacoustic spectroscopy revealed that the Cd-induced decrease in pigment content was very pronounced at the leaf surface
(stomatal guard cells) compared to the leaf interior (mesophyll). This observation was consistent with light transmission
and fluorescence microscopy analyses, which revealed that stomata density in the epidermis was noticeably reduced in Cd-exposed
leaves. Concomitantly, the stomatal conductance estimated from gas-exchange measurements was strongly reduced with Cd. When
plants were grown in a high-CO2 atmosphere (4,000 μl CO2 l−1), the inhibitory effect of Cd on growth was not cancelled, suggesting that the reduced availability of CO2 at the chloroplast level associated with the low stomatal conductance was not the main component of Cd toxicity in oilseed
rape.
Received: 14 July 2000 / Accepted: 27 August 2000 相似文献
8.
Heavy metal pollution of the soils around an abandoned Pb-Zn mine site located in the Alcudia Valley (South Central Spain) have been characterized by analysis of extractable and total metal concentrations in 60 samples of arable, pasture, and mine lands. The samples showed a broad range of size-particle distribution, cation exchange capacity, and pH values as well as high levels of total metal concentrations (up to 98510 mg kg?1 of Pb, up to 20912 mg kg?1 of Zn, and up to 61 mg kg?1 of Cd). In order to assess the potential availability of metals the metal partitioning in two different soil size fractions (<2 mm and <63 μm) was determined using EDTA and CaCl2 as sequestering reagents. The average contents of Pb, Zn, and Cd in the <63 μm particle size fraction for both extractions were higher than those of the <2 mm fraction due to the high metal adsorption capacity of the fine soil particles. Concentrations of heavy metals extracted by CaCl2 were up to three orders of magnitude lower than those extracted by EDTA, because CaCl2 only extracts the easily mobile fraction. Metal concentrations extracted by both procedures in the two granulometric fractions increased with total metal concentrations, thus increasing the potential environmental risk associated to heavy metal pollution. 相似文献
9.
- Calcium (Ca) signalling has an essential role in regulating plant responses to various abiotic stresses.
- This study applied Ca in various forms (Ca acetate and CaCl2) and concentrations to reduce cadmium (Cd) concentration in rice and propose a possible mechanism through which Ca acts to control the Cd concentration in rice.
- The results showed that supplementation of Cd‐contaminated soil with Ca acetate reduced the Cd concentration in rice after exposure for 7 days in both hydroponic and soil conditions. The possible involvement of the auto‐inhibited Ca2+‐ATPase gene (ACA) might act to control the primary signal of the Cd stress response. The messages from ACA3 and ACA13 tended to up‐regulate the low‐affinity cation transporter (OsLCT1) and down‐regulate Cd uptake and the Cd translocation transporter, including the genes, natural resistance‐associated macrophage protein 5 (Nramp5) and Zn/Cd‐transporting ATPase 2 (HMA2), which resulted in a reduction in the Cd concentration in rice. After cultivation for 120 days, the application of Ca acetate into Cd‐contaminated soil inhibited Cd uptake of rice.
- Increasing the Ca acetate concentration in the soil lowered the Cd concentration in rice shoots and grains. Moreover, Ca acetate maintained rice productivity and quality whereas both aspects decreased under Cd stress.
10.
Using iron fertilizer to control Cd accumulation in rice plants: A new promising technology 总被引:2,自引:0,他引:2
Shao GuoSheng Chen MingXue Wang DanYing Xu ChunMei Mou RenXiang Cao ZhaoYun Zhang XiuFu 《中国科学C辑(英文版)》2008,51(3):245-253
Effects of two kinds of iron fertilizer, FeSO4 and EDTA·Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil
culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth
and rice grain yield. Soil application of EDTA·Na2Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both
rice genotypes in the treatment of soil application of EDTA·Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentration in cereal crop foods in State standard. However,
soil application of FeSO4 or foliar application of FeSO4 or EDTA·Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control.
The results also showed iron fertilizers increased the concentration of iron, copper and manganese element in rice grain and
also affected zinc concentration in plants. It may be a new promising way to regulate Cd accumulation in rice grain in rice
production through soil application of EDTA·Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils. 相似文献
11.
M. Esfandbod A. Forghani E. Adhami M. Rezaei Rashti 《Soil & Sediment Contamination》2011,20(8):908-920
Cadmium (Cd) is a critical environmental chemical in which sorption reactions control its entry into soil solution. The aim of the present study was to evaluate Cd sorption characteristics of some soils of the northern part of Iran with a wide range of physicochemical properties. Duplicates of each sample were equilibrated with solutions containing 5 to 500 mg Cd L?1 with 0.01 M CaCl2 as background solution. The quantity of Cd retention was calculated as the difference between initial and equilibrated Cd concentration. Sorption isotherms including Freundlich, Langmuir, Temkin, Dubinin-Radushkevich, and Redlich-Peterson were used to evaluate the behavior of Cd sorption. Cadmium sorption data were well fitted to Langmuir, Freundlich, and Redlich-Peterson isotherms. The constant of Freundlich equation (kF ) and adsorption maxima (bL ) of Langmuir equation were related to pH and cation exchange capacity (CEC). The maximum buffering capacity (Kd ) was significantly correlated with pH (R2 = 0.52, p ≤ 0.001) and calcium carbonate equivalent (CCE) (R2 = 0.63, p ≤ 0.001). Redlich-Peterson constants (kRP and aRP ) were significantly correlated with pH (R2 kRP = 0.30, p ≤ 0.007) and (R2 aRP = 0.27, p ≤ 0.012). It seemed that pH, CEC, and CCE were the main soil properties regulating Cd retention behavior of the studied soils. 相似文献
12.
The effect of microorganisms on the fate of Cd introduced into the soil as cadmium oxide (CdO) was investigated. Cadmium oxide (875 µg Cd per gram of soil) was added to -irradiated (sterile) and non-sterile soils. The soils were incubated for 90 days at 18 °C under aerobic conditions with moisture kept at 60% of water-holding capacity. Half of the samples in each treatment were supplemented with starch (0.5%, w/w) in order to stimulate microbial growth in the non-sterile soil. After various time intervals (7- or 10-day), soil samples from each treatment were extracted with deionized distilled water (ratio 1:40) or 0.25 M CaCl2 (ratio 1:5). The results indicated that during the incubation period the amount of Cd extracted from the non-sterile soil with either solvent was markedly lower than that extracted from the -irradiated sterile control. The addition of starch to the non-sterile soil reduced the concentration of Cd in the 0.25 M CaCl2 extracts without affecting the Cd-content in the water extracts. Short-term experiments in which Cd was added to the soil as a solution of Cd(NO3)2 indicated that irradiation did not affect the sorption of Cd to the soil. The addition of bacterial mass (1 mg of dry weight g–1 soil) decreased the amount of Cd extracted with water as well as that extracted with 0.25 M CaCl2. Under sterile conditions the solubility of CdO in soil extracts was higher than in the other extractants. The addition of glucose (0.5%, w/w) or a glucose/starch mixture (0.5%, w/w of each) to the sterile soil increased the amount of extractable Cd after a short incubation (18 h at 18 °C). The obtained results suggest that primarily physicochemical reactions are involved in dissolving CdO in the soil but that microbial activity may be responsible for the immobilization of the released metal. 相似文献
13.
农田土壤镉(Cd)污染日益严重,导致稻米Cd含量超标事件频繁出现,使粮食安全问题备受关注。因此,合理利用Cd污染农田、降低水稻籽粒Cd含量成为亟待解决的问题。籽粒Cd低积累水稻雅恢2816的地上部具有较强的Cd积累能力,研究旨在弄清其地上部Cd积累能力的遗传稳定性,进一步揭示控制该性状的遗传基础,为利用分子标记辅助选育地上部Cd富集能力强、籽粒Cd安全的水稻提供途径。以水稻雅恢2816和3个不同品种水稻分别组配获得的F1为研究对象,分析地上部Cd积累相关性状的杂种优势。进一步以优势组合C268A/雅恢2816构建F2作图群体,对地上部Cd积累相关性状进行QTL定位分析。结果表明:(1) F1地上部Cd积累相关性状杂种优势明显,遗传稳定性强。地上部Cd积累相关性状属数量性状,F2中/超亲分离现象明显。(2)在第4、6号染色体上共挖掘到1个控制水稻地上部生物量和3个控制地上部Cd积累量的QTL位点,分别为qSB-6、qSCdA-4、qSCdA-6-1和qSCdA-6-2,表型贡献率为10.6%—14.4%,且增效等位基因均来自雅恢2816。(3)地上部Cd积累量与地上部生物量、Cd含量,根、糙米的生物量、Cd积累量,根-地上部转移系数均呈极显著正相关,与地上部-籽粒转移系数呈极显著负相关,存在4个QTL集簇区Cl-4-1、Cl-6-1、Cl-6-2和Cl-6-3。(4)区间marker 04171-marker 04197控制着地上部生物量和Cd积累量,与控制糙米Cd含量的QTL不重叠。研究表明:籽粒Cd低积累水稻雅恢2816携带控制地上部Cd高积累的等位基因,可在世代间稳定遗传,QTL位点qSCdA-4、qSCdA-6-1、qSCdA-6-2是控制该性状的重要遗传基础,可为分子标记辅助选育地上部Cd高积累、籽粒Cd低积累水稻提供理论依据。 相似文献
14.
The availability of most edible ectomycorrhizal mushrooms depends on their natural fructification. Sporocarp formation of
these fungi is linked to habitat characteristics and climate conditions, but these data alone do not explain all the trends
of fungal fruiting and dynamics. It could be hypothesized that the amount of soil mycelia could also be related to the production
of carpophores. Soil samples (five cylinders of 250 cm3 per plot) were taken monthly, from September to November, in five fenced permanent plots (5 × 5 m) in Pinar Grande (Soria,
Spain), a Pinus sylvestris stand situated in the north of the Sistema Ibérico mountain range. Plots were chosen to establish a gradient of Boletus edulis productivity from 0 to 38.5 kg/ha year, according to the mean fresh weight of sporocarps collected during the last 10 years.
B. edulis ectomycorrhizal root tips were identified in each soil sample according to its morphology and counted. DNA extractions were
performed with the PowerSoilTM DNA Isolation Kit and quantification of extraradical soil mycelium by real-time polymerase chain reaction using specific
primers and a TaqMan? probe. The concentration of soil mycelium of B. edulis (mg mycelium/g soil) did not differ significantly between plots (p = 0.1397), and sampling time (p = 0.7643) within the fructification period. The number of mycorrhizal short roots per soil volume showed significant differences
between the plots (p = 0.0050) and the three sampling times (p < 0.0001). No significant correlation between the number of mycorrhizas and the productivity of the plot (kg of B. edulis/ha year) was detected (p = 0.615). A statistically significant positive correlation (p = 0.0481) was detected between the concentration of mycelia of B. edulis in the soil samples and the presence of short roots mycorrhizal with B. edulis in these samples. The productivity of the plots, in terms of sporocarps produced during the last 10 years, was not correlated
either with the concentration of soil mycelium or with the presence or abundance of ectomycorrhizas. 相似文献
15.
A mixed culture of microorganisms able to utilize 4,6-dinitro-ortho-cresol (DNOC) as the sole source of carbon, nitrogen and energy was isolated from soil contaminated with pesticides and from
activated sludge. DNOC was decomposed aerobically in batch cultures as well as in fixed-bed column reactors. Between 65% and
84% of the substrate nitrogen was released as nitrate into the medium, and 61% of the carbon from uniformly 14C-labelled DNOC was recovered as 14CO2. The mixed microbial culture also decomposed 4-nitrophenol and 2,4-dinitrophenol but not 2,3-dinitrophenol, 2,6-dinitrophenol,
2,4-dinitrotoluene, 2,4-dinitrobenzoic acid or 2-sec-butyl-4,6-dinitrophenol (Dinoseb). Maximal degradation rates for DNOC by the bacterial biofilm immobilized on glass beads
in fixed-bed column reactors were 30 mmol day−1 (l reactor volume)−1, leaving an effluent concentration of less than 5 μg l−1 DNOC in the outflowing medium. The apparent K
s value of the immobilized mixed culture for DNOC was 17 μM. Degradation was inhibited at DNOC concentrations above 30 μM and
it ceased at 340 μM, possibly because of the uncoupling action of the nitroaromatic compound on the cellular energy-transducing
mechanism.
Received: 27 March 1997 / Received revision: 5 June 1997 / Accepted: 7 June 1997 相似文献
16.
Using iron fertilizer to control Cd accumulation in rice plants: A new promising technology 总被引:2,自引:0,他引:2
SHAO GuoSheng CHEN MingXue WANG DanYing XU ChunMei MOU RenXiang CAO ZhaoYun
& ZHANG XiuFu
《中国科学:生命科学英文版》2008,51(3):245-253
& ZHANG XiuFu
《中国科学:生命科学英文版》2008,51(3):245-253
Effects of two kinds of iron fertilizer, FeSO4 and EDTA·Na2Fe were studied on cadmium accumulation in rice plants with two rice genotypes, Zhongzao 22 and Zhongjiazao 02, with soil culture systems. The results showed that application of iron fertilizers could hardly make adverse effects on plant growth and rice grain yield. Soil application of EDTA·Na2Fe significantly reduced the Cd accumulation in rice roots, shoots and rice grain. Cd concentration in white rice of both rice genotypes in the treatment of soil application of EDTA·Na2Fe was much lower than 0.2 mg/kg, the maximal Cd permission concentra- tion in cereal crop foods in State standard. However, soil application of FeSO4 or foliar application of FeSO4 or EDTA·Na2Fe resulted in the significant increase of Cd accumulation in rice plants including rice grain compared with the control. The results also showed iron fertilizers increased the concentra- tion of iron, copper and manganese element in rice grain and also affected zinc concentration in plants. It may be a new promising way to regulate Cd accumulation in rice grain in rice production through soil application of EDTA·Na2Fe fertilizers to maintain higher content of available iron and ferrous iron in soils. 相似文献
17.
The biodegradation of tributyl phosphate (Bu3-P, TBP), releasing phosphate at a high enough concentration locally to precipitate uranium from solution, was demonstrated
by a mixed culture consisting primarily of pseudomonads. The effect of various parameters on Bu3-P biodegradation by growing cells is described. Growth at the expense of Bu3-P as the carbon and phosphorus source occurred over a pH range from 6.5 to 8, and optimally at pH 7. Bu3-P biodegradation was optimal at 30 °C, reduced at 20 °C and negligible at 4 °C and 37 °C. Incorporation of Cu or Cd inhibited,
and Ni, Co and Mn reduced its degradation. Inorganic phosphate (above 10 mM) and kerosene (up to 1 g/l) reduced Bu3-P biodegradation significantly, but nitrate had no effect. Sulphate (10–100 mM) was inhibitory. When pregrown biomass was used
the fastest rates of tributyl and dibutyl phosphate biodegradation were 25 μmol h−1 mg protein−1 and 37 μmol h−1 mg protein−1 respectively. Microcarrier-immobilised biomass decontaminated uranium-bearing acid mine waste water by uranium phosphate
precipitation at the expense of Bu3-P hydrolysis in the presence of 35 mM SO4
2−. At pH 4.5, 79% of the UO2
2+ was removed at a flow rate of 1.4 ml/h on a 7-ml test column.
Received: 2 June 1997 / Received revision: 15 September 1997 / Accepted: 19 September 1997 相似文献
18.
Jaeho Cha M. V. Sørensen Q.-Z. Ye D. S. Auld 《Journal of biological inorganic chemistry》1998,3(4):353-359
We have selectively replaced the catalytic zinc of the catalytic domain of stromelysin-1 (SCD) with other transition metals.
Dialysis of the enzyme against 2 mM 1,10-phenanthroline, 20 mM Hepes, pH 7.5 in the presence of 10 mM CaCl2 removes the catalytic zinc, leaving the structural zinc site intact. Dialysis with metal-free buffer followed by the new
metal ion replaces the catalytic zinc forming a metal hybrid enzyme. Full incorporation of 1 mol Co2+, Ni2+, or Cd2+/mol enzyme is confirmed by atomic absorption spectrometry while the weaker binding Mn2+ yields a value of 0.4 mol Mn2+/mol enzyme after dialysis against 1 μM Mn2+. The activity of the monozinc enzyme is <10% while its activity is restored upon the addition of zinc and other transition
metals. The k
cat values for the Co2+, Mn2+, Cd2+, and Ni2+ enzymes are respectively 99%, 54%, 19%, and 17% of the value for the native enzyme, while the respective k
cat/K
m values are 36%, 29%, 7%, and 16% toward the fluorescent heptapeptide substrate, DnsPLALRAR. The zinc and metal hybrid SCD
cleave DnsPLA↓LRAR, and DnsPLE↓LFAR, exclusively at one bond, while DnsPLA↓L↓WAR and DnsPLA↓L↓FAR are cleaved at two positions.
The double cleavage of DnsPLALWAR and DnsPLALFAR catalyzed by SCD is in marked contrast to the close structurally related
matrilysin. A notable feature of SCD catalysis is the different cleavage site specificity of the metal hybrids toward the
A-L and L-W bonds of the DnsPLALWAR substrate. Thus the k
cat values of the Co/Zn hybrid for the cleavage of the A-L bond in the DnsPLALRAR and DnsPLAWAR substrates are 5- and 8-fold
greater than those for the Cd/Zn hybrid compared to a 140-fold difference for the corresponding k
cat values for the L-W bond cleavage. These results imply that the catalytic metal of SCD is not only involved in catalysis but
also influences the substrate specificity of the enzyme.
Received: 30 December 1997 / Accepted: 23 February 1998 相似文献
19.
The growth and some physiological responses of rice to Cd toxicity as affected by nitrogen form 总被引:1,自引:0,他引:1
Muhammad Jaffar Hassan Muhammad Shafi Guoping Zhang Zhujun Zhu Mahmood Qaisar 《Plant Growth Regulation》2008,54(2):125-132
A hydroponic experiment was conducted to examine the effect of Cd stress on anti-oxidative enzyme activities at heading stage,
yield components, root exudation and Cd and N uptake of rice plants grew in different N source i.e. (NH4)2SO4, NH4NO3 and Ca(NO3)2. The results show that the effect of Cd stress on all measured parameters were N source dependent. Cd stress (1 μM) caused
a remarkable reduction in grain yield and shoot biomass, an increase in root exudation, glutathione content, Cd concentration
and catalase (CAT) and peroxidase (POD) activities of rice plants. In the plants under the control (without Cd addition) N
source had no distinctive effect on the above measured parameters, but the differences among the three N forms in these parameters
became significant when plants were exposed to Cd stress. Cd stress significantly increased POD and CAT activities, and gultathione
content, with Ca(NO3)2-fed plants having the greatest POD and CAT activities and lowest glutathione content, and (NH4)2SO4-fed plants being just opposite. Moreover, organic acid exudation varied also with N form for the Cd-stressed plants. In comparison
with other two N forms, (NH4)2SO4,-treated plants had higher grain yield, N concentration and lower Cd concentration in plants. The current results indicated
that (NH4)2SO4 is a better fertilizer for use in Cd contaminated soil. 相似文献
20.
Małgorzata Majewska Jolanta Jaroszuk-Ściseł 《International journal of phytoremediation》2017,19(8):701-708
Mobilization of cadmium accumulated in Festuca ovina L. roots and simultaneous immobilization of this metal by soil were studied in three chambers connected into one system containing: (1) roots in an extractant solution, (2) soil in an extractant solution, and (3) extractant solution alone. Six extractants sterilized by filtration were used: 0.1 M NaNO3 (NA), 0.1 mM desferrioxamine B (NA + DFOB) and 1 mM citric acid (NA + CA) in NA, and a water extract of soil (SE) supplemented with the same compounds. SE mobilized 53% of the Cd introduced to the system with roots. The addition of DFOB or CA to SE increased Cd extraction from roots by 17%, while the same compounds introduced to NA did not change mobilization of Cd (60% efficiency). Regardless of the extractant used, mobilization of Cd from roots was about 25% lower when extraction was done in a control system without soil. The metal released from roots was gradually immobilized by the soils loaded into all systems during a 4-day incubation. Sequential extractions of Cd from the soils showed that the metal released from roots with NA was stabilized mainly by soil Mn and Fe oxides, while that released with SE was stabilized by soil organic matter. 相似文献