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1.
From acidic tea soils of Kagoshima Prefecture in Japan, some soil properties were determined and 38 strains of acid tolerant microorganisms were isolated. Different Al3+ concentrations were applied to YG media to estimate Al resistance. Selected microbial strains could grow strongly in the liquid media in the presence of 100 mM Al3+ and survive even in 300 mM Al3+ at pH 3.0. Their base sequences of 28S rDNA-D1/D2 were determined and sequence data were searched using the Basic Local Alignment Search Tool (BLAST) system. The results of sequencing revealed that the isolates belong to two different species, Cryptococcus sp. and Candida palmioleophila. When cultivated with various Al3+ concentrations, the yeast growth was inhibited at a concentration of 200 mM. Pre-cultivation of these strains with 0–30 mM Al3+ did not promote the growth response caused by Al3+. Inductively-Coupled Plasma-Mass Spectrometry (ICP-MS) was used to assess the elimination of Al. The amount of Al remaining in culture media was decreased considerably after cultivation. Due to a capacity for resistance to significant Al concentrations as well as high Al elimination, these acid tolerant and Al resistant yeasts may have potential applications in the bio- and phyto-remediation of Al and acid-contaminated soils.  相似文献   

2.
Potassium transport was investigated in the root elongation zone of Arabidopsis seedlings during the first minutes of Al3+ exposure, using the non-invasive MIFE microelectrode technique. To prevent pH changes during Al3+ application, and to separate aluminium from acidic stress, plants were pre-treated with 5 mM homoPIPES before addition of AlCl3 (pH 4.2). The 30-min treatment with 50 or 500 μM AlCl3 led to a significant increase in K+ efflux in solutions containing 100 μM CaCl2. This efflux was suppressed by high concentrations of Ca2+ (10 mM) in the bathing solution. Our results suggest that elevated external Ca2+ activities can sustain K+ influx in the root elongation zone during Al3+ exposure either by maintaining [Ca2+]cyt or by affecting Al3+ uptake across the plasma membrane.  相似文献   

3.
We examined the aluminium solubility in the upper B horizon of podzols and its relation to the solid phase of the soil in 60 samples covering a pH range from 3.8 to 5.1. Solid phases were characterized by extractions with acid oxalate and pyrophosphate (pH 10). The solubility of Al was studied in a batch experiment in which samples were equilibrated with 1 m m NaCl at 8°C for 5 days. We also monitored the dissolution kinetics of Al and Si, in some samples. The oxalate and pyrophosphate extractions suggested that secondary Al was mainly organically bound in most soils, and imogolite-type materials seemed to constitute much of inorganic secondary Al. No single gibbsite or imogolite equilibrium could explain Al3+ activities. In all samples Al solubility, defined as log{Al3+} + 1.65pH, was closely related to the molar ratio of aluminium to carbon in the pyrophosphate extracts (Alp/Cp). Solubility increased with the Alp/Cp ratio until the latter reached ≈ 0.1. This indicated that solubility was controlled by organic complexation, at least when Alp/Cp was small. Silica dissolved slowly in most soils used in the kinetic experiments. We conclude that imogolite-type materials in the upper B horizon dissolved slowly because of coating with humic substances or ageing or both.  相似文献   

4.
Long-term acidification has been shown to result in a considerable decrease in the amount of organically bound soil Al and in a gradual decrease in the solubility of Al. We examined the solubility of soil organic matter (SOM) and Al in four acid mineral soils (one Arenosol Ah, two Podzol Bh, and one Podzol Bs) as they were leached sequentially using a solution containing 0.001 m HCl and 0.01 m KCl. The acid leaching resulted in relative decreases in Al that were 2–6 times greater than for organic C. The organic C and Al dissolved by the acid leaching originated mainly in the pyrophosphate-extractable fraction of the elements. Protonation seems to be a major mechanism in stabilizing the residual SOM, as indicated by small changes in effective cation exchange capacity with the degree of acid leaching. In the samples of Podzol Bh and Arenosol Ah soils the solubility of Al (defined as log10{Al3+} + 1.5pH) in equilibrium suspensions (0.01 m KCl) was closely related to the ratio of pyrophosphate-extractable Al to pyrophosphate-extractable organic C. The Podzol Bs sample probably contained a small amount of a surface-reactive Al(OH)3 phase, which rapidly became depleted by the acid leaching.  相似文献   

5.
Thirty-one soil solutions were extracted by immiscible displacement with CCl4 under high speed centrifugation from sub-horizons of three podzolic soils from north-eastern Ontario, Canada. The solutions were analysed for major cations and anions and a speciation of dissolved Fe and Al was attempted to distinguish 'free', 'organically bound' and 'inorganically bound' species. Results indicated that the Ae (E) horizon solutions were of low pH and contained mainly organically bound Fe and Al. With depth, pHs increased, ionic strengths decreased and the relative proportion of inorganically bound Fe and Al increased. Although application of phase diagrams permitted only a semi-quantitative interpretation of the data, all horizon solutions, with the exception of some Ae solutions, appeared supersaturated with respect to likely occurring crystalline and amorphous aluminosilicates [kaolinite, halloysite, allophane (Al:Si=l) and imogolite]. Of the phases considered, reactions involving imogolite-allophane, gibbsite-halloysite, gibbsite-allophane and gibbsite-imogolite all appeared reasonable in controlling the content of Al3+ and H4SiO4 in solution, although the presence of gibbsite and imogolite could not be definitely confirmed in these soils.  相似文献   

6.
The retention walls in a pond containing the residues from the pyrite mine of Aznalcóllar (southern Spain) broke open on 25 April 1998, spilling approximately 6 × 106 m3 of polluted water and toxic tailings, which affected some 55 km2. Drying and aeration of the tailings resulted in oxidation, forming an acidic solution with high pollutant contents, the effects of which were studied in a calcareous soil. The infiltration of this solution markedly affected only the first 12 mm of the soil, where strong acidification caused the weathering of the carbonates, and where the fine mineral particles were hydrolysed. The SO42− ions in the acidic solution precipitated almost entirely at this depth, forming gypsum, hydroxysulphates and complex sulphates. The Fe3+ ions also precipitated there, mainly in amorphous or poorly crystallized forms, adsorbing to As, Sb, Tl and Pb dissolved in the acidic solution. The Al3+ ions, though partly precipitating in the acidic layer, accumulated mostly where the soil pH exceeded 5.5 (12–14 mm in depth). They did so primarily as amorphous or poorly crystallized forms, adsorbing to Cu dissolved in the acidic solution. The Zn2+ and Cd2+ ions accumulated mainly at pH > 7.0 (19–21 mm in depth), being adsorbed chiefly by clay mineral. After 15 months, only the first 20 mm of the soil were acidified by the oxidation of the tailings and most of the pollutants did not penetrate deeper than 100 mm. Consequently, the speed of the cleanup of the toxic spill is not as important as a thorough removal of tailings together with the upper 10 cm of the soil.  相似文献   

7.
The origin of highly acidic (pH<4.5) barren soils in the Klamath Mountains of northern California was examined. Soil parent material was mica schist that contained an average of 2,700 mg N kg−1, which corresponds to 7.1 Mg N ha−1 contained in a 10-cm thickness of bedrock. In situ soil solutions were dominated by H+, labile-monomeric Al3+ and NO3−, indicating that the barren area soils were nitrogen saturated—more mineral nitrogen available than required by biota. Leaching of excess NO3− has resulted in removal of nutrient cations and soil acidification. Nitrogen release rates from organic matter free soil ranged from 0.0163 to 0.0321 mg N kg−1 d−1. Nitrogen release rate from fresh ground rock was 0.0465 mg N kg−1 d−1. This study demonstrates that geologic nitrogen may represent a large and reactive nitrogen pool that can contribute significantly to soil acidification.  相似文献   

8.
The cation composition of solutions and leachates from small-diameter laboratory soil columns was examined over a 23-week period after the addition of lime (0, 3 and 6 t ha–1) and/or nitrogen fertilizer (0 or 200 kg N ha–1) to an acid soil (pH 4.2). Water was applied at regular intervals to the surface of the columns and 17 leachate samples collected. Initially, the pH of the leachate was high (6.6) in all treatments (including those without lime) but fell rapidly to approach a steady value of 3.8. Large losses of calcium occurred from all columns; the total equivalent amounts of lime lost ranged from 0.88 (no addition) to 2.38 (with added lime) t CaCO3 ha–1 High concentrations of aluminium (181–325 μM) were present in leachates from all treatments; the addition of 200 kg N ha–1 increased the leaching of Al by 94%; addition of lime also increased the amounts of Al leached (by 52%).
The pH of the soil solution (separated by centrifugation) was influenced by treatment, especially in the top 0–40 mm of the column. Aluminium concentration was related to pH, but the form of the relationship differed amongst the treatments.  相似文献   

9.
We studied the effect of repeated application (once every 2 d) of a fertilizer solution with different ratios of NH4+ - and NO3−-N on N2O emission from soil. After the excess fertilizer solution was drained from soil, the water content of soil was adjusted to 50% of the maximum water-holding capacity by suction at 6 × 103 Pa. Repeated application of NH4+- rich fertilizer solution stimulated nitrification in soil more than NO3−-rich fertilizer. Although the evolution of N2O through nitrifier denitrification tended to increase with the repeated addition of a fertilizer solution rich in NH4+ rather than in NO3−, the contribution of nitrifier denitrification remained at levels of 20 to 36% of the total emission regardless of the inorganic N composition. The total emission of N2O also tended to increase with the application of NH4+- rather than NO3−-rich fertilizer. It was suggested that the coupled process of nitrification and denitrification at micro-aerobic sites became important when fertilizer rich in NH4+ was applied to soil under relatively aerobic conditions.  相似文献   

10.
A 3-year field trial examined in a long-term no-till system the effects of surface-applied lime and cover black oat ( Avena strigosa Schreb) residues on soil chemical attributes, root growth and grain yield of corn ( Zea mays L.) and soybean ( Glycine max L. Merrill) on a loamy, kaolinitic, thermic Typic Hapludox in Paraná State, Brazil. The treatments consisted of dolomitic lime broadcast on the soil surface at 0 or 12 t/ha, with and without cover of black oat residues. Corn and soybeans were grown without rainfall limitation. Applying lime on the surface improved soil acidity and decreased aluminium (Al) toxicity to a 10-cm depth 1 year after application. Surface liming increased pH and the content of exchangeable Ca2+ to a 20-cm depth, and decreased Al toxicity to a 40- to 60-cm depth, 3 years after application, indicating that the surface-applied lime moved deeper. Cover black oat residues did not favour the mobility of surface-applied lime to alleviate subsoil acidity and an increase in the Al3+ saturation level at the soil surface was found in unlimed plots with black oat residues. Root growth and grain yields of corn and soybean were not influenced by surface liming with or without cover black oat residue. Despite the soil acidity level, root length of corn and soybean ranged from 55 to 60% at 0- to 10-cm depth. The results suggest that Al toxicity is low in no-till systems during cropping seasons with adequate and well-distributed rainfall, but this effect is not related to the presence of cover oat residues.  相似文献   

11.
A plot with a high aluminum (Al) concentration in soil solution was found in Kumagaya, central Japan; the maximum was 4.0 mg L−1 as total dissolved Al (TD-Al) at a depth of 10 cm in August 2000. The soil type was Dystric Andosols with three horizons, A/Bw1/Bw2, which contained a considerable quantity of Al extracted by dithionite-citrate and acid-oxalate extractants. The upper two horizons were acidic with soil pH (H2O) of 4.4 and 4.6. The fundamental cause of the high TD-Al concentration was the low pH with a very low base saturation of less than 2%. The seasonal change in TD-Al concentrations in soil solution at a depth of 10 cm was significantly and positively correlated with the nitrate concentrations but weakly and rather negatively correlated with the sulfate concentrations. Nitrification functioned as the direct acid source to cause the TD-Al concentrations to fluctuate strongly, whereas sulfate adsorption onto the soil at the research plot functioned as a sink of proton.  相似文献   

12.
硫酸铝对苏打盐碱土中氟迁移规律的影响   总被引：2，自引：0，他引：2  
采用土柱淋洗法,研究不同铝氟摩尔比下苏打盐碱土中氟的迁移过程及pH值变化情况。结果表明,苏打盐碱土施铝后,能够明显降低淋洗液的pH值,与空白相比,差异均达极显著水平。并且随着淋洗次数和铝相对含量的增加,pH值呈现逐渐降低的趋势。不同铝氟摩尔比作用下,氟在碱土中的迁移动态及总淋失率存在较大的差别。随着淋洗次数的增加,1∶1处理的每次淋失率变化较缓,(1∶2)～(1∶4)处理呈先增加后降低的趋势,而(1∶5)～(1∶7)处理明显下降。与对照相比,苏打盐碱土上施用硫酸铝可以降低氟在土壤中的总淋失量,进而可以减少土体中的氟向地下水中的迁移,降低人畜通过饮用地下水而带来的摄氟量。但是氟总淋失率的降低程度与铝的相对含量有关,其中1∶4铝氟处理的总淋失率相对较高,而1∶1处理的淋失率相对较低。这可能与添加硫酸铝后苏打盐碱土的pH值变化、铝氧化物和氢氧化物数量变化、土壤胶体带电性变化及土壤自身铝的释放有关。  相似文献   

13.
Surface and subsurface samples of three tropical soils were examined with respect to their interaction with dilute solutions of sulphuric acid of pH 3. In calcareous clayey samples with a large cation exchange capacity the H+ was replaced by an equivalent concentration of metal cations which remained in solution along with SO2-4 as counterion. In a coarse-textured neutral soil with small cation exchange capacity, there was less chemical interaction and a major proportion of the H2SO4 remained unchanged in the equilibrium solution. Another soil exhibited considerable ability to remove SO2-4 from solution and, therefore, the total ionic concentration was greatly reduced. Other samples showed behaviour which was intermediate to these three types.
The ability to adsorb SO2-4 is one of the most important factors which determines the nature of the interaction of soil with dilute sulphuric acid. This ability was shown to be affected by the content of hydrous sesquioxides and organic matter in these soils.  相似文献   

14.
To study the mechanisms of Al tolerance in rice, we focused on the change of rhizosphere pH. The 4-d seedlings were treated with Al solution (0, 10, 50 mM) for 24 h. Then each sample was put on an agarose gel including bromocresol green, so that the color of the gel indicated pH change. During 2-h contact, the pH of rhizosphere was decreased gradually, especially for Al-treated samples, showing the specific pH profiles along the root axis. Pretreatment of sample plants with a decoupling reagent 2,4-dinitrophenol (DNP) or a plasma membrane H+-ATPase inhibitor Na3VO4 did not decrease rhizosphere pH. Therefore, it was suggested that the H+ secretion activity was involved with Al-tolerant mechanisms of rice.  相似文献   

15.
Abstract. The aim of this study was to investigate the effects of water submergence depth on radial oxygen loss (ROL), soil solution chemistry and rice growth performance in acid sulphate soils in southern Vietnam. ROL was measured in a solution culture. In a separate pot experiment the impact of water submergence depth on rice growth and soil solution chemistry was studied. Three submergence depths were used in the two experiments (5, 10 and 15 cm). ROL declined with submergence depth and was significantly greater in young roots (with no root hairs) than in older roots. In the pot experiment rice growth and soil solution chemistry were clearly affected by the submergence depth. During the first crop at 5 cm submergence, there was a significantly higher yield and a higher oxidation state (pe+pH) compared to 10 or 15 cm submergence. The Fe concentration was significantly greater at the 5 cm depth compared to the 10 or 15 cm depth. SO42– reduction was delayed at the 5 cm depth. Rice yield was c. 25% less at the 15 cm than at the 5 cm depth. During a second crop, there was a substantial SO42- reduction and H2S formation and almost no significant effects of submergence depth on either soil solution chemistry or crop yield. In a field experiment with a dry-season rice crop, yield and Fe, Al and SO42– concentrations were higher at a shallow submergence depth than at greater depths in the same field, showing similar depth trends to those found during the first crop in the pot experiment. Farmers should be advised to use a shallow submergence depth and, if possible, avoid deep-rooted rice varieties. A conceptual model is suggested, which summarizes the relationships between ROL and soil solution chemistry.  相似文献   

16.
The effect of pH on the adsorption of copper (Cu), lead (Pb) and cadmium (Cd) by a peat soil was studied, and the results compared with those corresponding to cation binding by a dissolved peat humic acid (HA), and interpreted with a NICA–Donnan model. A potentiometric titration technique was used to determine the adsorption isotherms for H+, at different ionic strengths, and for Cu2+, Pb2+ and Cd2+ at different pH values, in a peat soil. The effect of the ionic strength on proton binding was similar for the soil (solid) organic matter and for dissolved HA. The adsorption isotherms for cation–peat and the binding curves cation–dissolved HA are almost parallel, although more cation was adsorbed per kg of C in the dissolved HA. The effect of pH on cation binding is similar for dissolved organic matter and for the organic soil. At low metal concentration the amount of adsorbed metal followed the order Cu2+ > Pb2+ > Cd2+. The cation-binding parameters obtained with the NICA–Donnan model allow excellent simulation of the effect of pH on the adsorption of Cu, Pb and Cd ions in the studied peat soil. The binding constants for the peat suspension were greater than the corresponding generic parameters for dissolved HA. Speciation calculations showed that for Cu and Pb, the most abundant fraction was the metal adsorbed on peat, whereas for Cd the most abundant fraction was dissolved metal.  相似文献   

17.
We investigate the effect of Al on K+ uptake by rice roots. Potassium-38 (38K), a positron emitting nuclide (the half-life: 7.61 min), was used to trace K+ behavior. When a rice root was treated with 10μM Al for 24 h, the uptake of 38K in the root was increased in the range of 1 to 2 cm from the root tip compared with that of the control sample. Because the root continued to grow without showing any damage of plasma membrane during the Al treatment, it was suggested that the 38K uptake was not occurred through diffusion into the cells. The uptake of 38K in both treatments, with/without Al, was decreased by VO43- (inhibitor of H+-ATPase on plasma membrane) and DNP (H+ ionophore) treatment, which suggested that the K+ uptake was performed through an active transport, such as H+:K+ transport or H+ gradient promoted by an Al treatment.  相似文献   

18.
Effects of salt (NaCl : Na2SO4) and alkali (NaHCO3 : Na2CO3) stresses on the contents of inorganic ions and organic solutes in wheat shoots were compared to explore the physiological responses and adaptive strategies of wheat to these stresses. Wheat significantly accumulated Na+ and simultaneously accumulated Cl−, soluble sugars and proline to maintain osmotic and ionic balance under salt stress. Compared with salt stress, the high pH from alkali stress enhanced Na+ accumulation and affected the absorption of inorganic anions. To maintain ionic and osmotic balance, wheat accumulated organic acids, soluble sugars and proline. The accumulation of Cl− and organic acids was the main difference in the physiological responses and adaptive mechanisms to salt and alkali stresses, respectively.  相似文献   

19.
施用碱稳定污泥污水土壤经γ-辐照后土壤溶液中Cu和Zn   总被引：1，自引：0，他引：1  
Soil samples collected from several acid soils in Guangdong, Fujian, Zhejiang and Anhui provinces of the southern China were employed to characterize the chemical species of aluminumions in the soils. The proportion of monomeric inorganic Al to total Al in soil solution was in the range of 19% to 70%, that of monomeric organic Al (Al-OM) to total Al ranged from 7.7% to 69%, and that of the acid-soluble Al to total Al was generally smaller and was lower than 20% in most of the acid soils studied. The Al-OM concentration in soil solution was positively correlated with the content of dissolved organic carbon (DOC) and also affected by the concentration of Al3+. The complexes of aluminum with fluoride (Al-F) were the predominant forms of inorganic Al, and the proportion of Al-F complexes to total inorganic Al increased with pH. Under strongly acid condition, Al3+ was also a major form of inorganic Al, and the proportion of Al3+ to total inorganic Al decreased with increasing pH. The proportions of Al-OH and Al-SO4 complexes to total inorganic Al were small and were not larger than 10% in the most acid soils. The concentration of inorganic Al in solution depended largely on pH and the concentration of total F in soil solution. The concentrat ions of Al-OM, Al3+, Al-F and Al-OH complexes in topsoil were higher than those in subsoil and decreased with the increase in soil depth. The chemical species of aluminumions were influenced by pH. The concentrations of Al-OM, Al3+, Al-F complexes and Al-OH complexes decreased with the increase in pH.  相似文献   

20.
In acid soils in the Eastern Plains of Colombia, forage grasses planted on land prepared before the previous dry season produced 40–50% more dry matter than when land was prepared immediately before planting. Virtually no NO3− accumulated in surface (0–10 cm) soil from three native undisturbed savanna sites. Where land was ploughed before the dry season, NO3− levels increased gradually after a 2–3 month lag, and dropped at the beginning of the rains. In samples incubated for 4 weeks, more NO3− accumulated in the wet than the dry season. A similar 2–3-month lag occurred when land was ploughed after the dry season. NH4+ levels were higher in ploughed than savanna soils, and rose in all soils at the beginning of the rains. More NO3− and NH4+ accumulated on incubation in pots than in soil cores. Forage grasses inhibited NO3− accumulation in the soil, relative to plant-free plots, and legumes stimulated it. N fertilization overcame this inhibition except in the case of Brachiaria humidicola .  相似文献   

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