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1.
Bacterial strains amended to soil to facilitate bioremediation of sites contaminated with organic substances must be capable
of surviving and functioning in the presence of a variety of soil organic and mineral components. Thus, the influence of humic
acid on 2-hydroxypyridine catabolism, retention of 2-hydroxypyridine catabolic activity by whole cells, and hydrophobicity
of the Arthrobacter crystallopoietes cells was examined. Humic acid, added to the starvation medium of the arthrobacter cells, which had been acclimated to catabolize
2-hydroxypyridine, resulted in increased stability of this metabolic activity compared to that of comparable cells starved
in the absence of humic acid. For example, after 7 days starvation, cells incubated in the presence of 0.1% (wt/vol) humic
acid oxidized 2-hydroxypyridine at a rate of 54.9μmolh–1 compared to 14.6μmolh–1 in the absence of humic acid. Although after 1 day starvation 2.5-fold more 2-hydroxypyridine-catabolizing activity was detected
in the presence of humic acid than in its absence, this enzymatic activity declined to undetectable levels after 3 days starvation
both with and without humic acid in the starvation medium. No effect of humic acid was noted on protein content of the cells.
Hydrophobicity of the cells was not affected by humic acid during the first 4 days of starvation but after 7 days humic acid
lessened the reduction in this property. Thus, changes in cell protein content and hydrophobicity did not explain the effect
of humic acid on 2-hydroxypyridine catabolism of starving A. crystallopoietes cells.
Received: 21 March 1996 相似文献
2.
黏粒矿物影响着土壤理化性质，可指示成土因素特征和土壤发生发育过程/强度，也是中国土壤系统分类的基层单元土族矿物学类型划分的重要依据。本研究选择了广西不同纬度和成土母质的18个代表性水耕人为土的剖面，应用X射线衍射（XRD）方法分析了其典型水耕氧化还原层（Br层）的黏粒矿物组成及其空间分布特征，并确定了其中“黏质”剖面的土族控制层段矿物学类型。结果表明：（1）供试土壤的黏粒矿物主要包括高岭石、伊利石、三水铝石、1.42 nm过渡矿物、蒙脱石和蛭石等，依次分别出现在100%、88.9%、72.2%、61.1%、44.4%和38.9%的剖面中。（2）黏粒矿物组成在纬度空间分布上具有明显规律性特征。随着纬度降低，土壤黏粒中的高岭石增加，伊利石、蒙脱石、1.42nm过渡矿物逐渐减少；纬度＞23°N区域内，成土母质对黏粒矿物组成影响明显。（3）纬度23°N是黏粒矿物组成和土族矿物学类型分界线，＜23°N区域，黏粒矿物均以高岭石为主，是“黏质”剖面的土族控制层段的主要矿物学类型；＞23°N区域，黏粒矿物组成以高岭石、蒙脱石、伊利石或1.42 nm过渡矿物为主，因成土母质不同而异，“黏质”剖面的土族控制层段矿物学类型包括高岭石混合型、混合型和伊利石型。 相似文献
3.
Xinhong GAN Ying TENG Jian XU Ning ZHANG Wenjie REN Ling ZHAO Peter CHRISTIE Yongming LUO 《土壤圈》2022,32(2):246-255
Clay minerals play an important role in biogeochemical cycling. Here, kaolinite and montmorillonite, the two most abundant and widespread clay minerals with typical layered structures, were selected to investigate and compare their effects on the biodegradation of benzo[a]pyrene (BaP) by Paracoccus aminovorans HPD-2 and to investigate the underlying interface mechanisms. Overall, the BaP degradation efficiency was significantly higher 7 d after montmorillonite addition, reaching 68.9% (P < 0.05), when compared with that of the control without addition of clay minerals (CK, 61.4%); however, the addition of kaolinite significantly reduced the BaP degradation efficiency to 45.8%. This suggests that kaolinite inhibits BaP degradation by inhibiting the growth of strain HPD-2, or its strong hydrophobicity and readily agglomerates in the degradation system, resulting in a decrease in the bio-accessibility of BaP to strain HPD-2. Montmorillonite may buffer some unfavorable factors, and cells may be fixed on the surface of montmorillonite colloidal particles across energy barriers. Furthermore, the adsorption of BaP on montmorillonite may be weakened after swelling, reducing the effect on the bio-accessibility of BaP, thus promoting the biodegradation of BaP by strain HPD-2. The experimental results indicate that differential bacterial growth, BaP bio-accessibility, interface interaction, and the buffering effect may explain the differential effects of the different minerals on polycyclic aromatic hydrocarbon biodegradation. These observations improve our understanding of the mechanisms by which clay minerals, organic pollutants, and degrading bacteria interact during the biodegradation process and provide a theoretical basis for increasing the biodegradation of soil pollutants by native microorganisms under field conditions. 相似文献
4.
The mineralogical composition of clays (< 2μm) in representative profiles of all soil types of Israel was investigated. The soils were classified according to their clay mineral assemblages into three groups. I. Montmorillonitic soils. Montmorillonite is the dominant mineral and exceeds 65 per cent of the total minerals found; each of the other minerals comprises less than 15 per cent. 2. Montmorillonitic-kaolinitic soils. The soil clay fractions contain 50-60 per cent montmorillonite and 15-25 per cent kaolinite, generally adding up to more than 75 per cent of the clay fraction. 3. Montmorillonitic-calcitic soils. The clays contain more than 10 per cent calcite. Montmorillonite is the dominant clay mineral (except for one soil type, mountain rendzina, where calcite is dominant). The first and second assemblages are typical of the soils of the Mediterranean zone, whereas the soils of the desert zone are characterized by the third assemblage. The origin of montmorillonite, kaolinite, and illite, the three main clay minerals, was found to be detritic, as was the origin of palygorskite which was mainly found in the calcite rich soils of the desert zone. The cation exchange capacity of montmorillonite seems to be higher under higher precipitation. Montmorillonite content and cation exchange capacity of the clays were found to be highly correlated. The carbonate content of the clay fraction and the amount of carbonate in the soil were also highly correlated. 相似文献
5.
西藏高原突起于我国西南,绝大部分地面的海拔高度在4000米以上,为世界上最高的大高原。它大致在第三纪开始形成,后来曾受第四纪冰川的深刻作用,高山顶部至今仍是冰川的活动场所[1,2]。高原为昆仑山、唐古拉山、喜马拉雅山和横断山等大山脉所盘踞。 相似文献
6.
Giacomo Pietramellara Judith Ascher Maria Teresa Ceccherini Paolo Nannipieri Dirk Wenderoth 《Biology and Fertility of Soils》2007,43(6):731-739
Several studies have investigated the adsorption of pure DNA on soil particles and its transformation ability. However, the presence of not purified (dirty) rather than pure DNA is more common in the extracellular soil environment. For this reason, we have investigated the adsorption
and binding of dirty DNA on montmorillonite (M) and kaolinite (K) and their transforming ability in comparison to pure DNA.
After lysis of Bacillus subtilis cells, induced by KCl, dirty DNA was characterized by the presence of cellular wall debris (cwd) and other constitutional organic components (coc). The dirty DNA was then divided into two fractions, one with cellular wall debris (DNA +cwd) and the other without cellular
wall debris (DNA −cwd). B. subtilis BD 1512 (Cmr) and BD 170 (Cms) were selected as donor and recipient bacteria, respectively, for adsorption and transformation studies. Both cwd and coc
seem to facilitate the adsorption of DNA to clay minerals, whereas only cwd promote the DNA binding on clays, protecting also
the DNA fragments below 400 bp against nucleases. Both dirty DNA fractions adsorbed and bound on clay minerals were able to
transform competent cells. 相似文献
7.
Influence of two- and three-layered clay minerals on the Dehydrogenase-, acid Phosphatase and Urease Activity in model experiments The influence of different Ca-homo-ionic clay minerals as well as humic acid (Roth) on the dehydrogenase activity (DHA) as well as on urease and acid phosphatase were examined in model experiments. The following results were obtained: 1. The DHA of a fertile soil and the activity of urease and acid-phosphatase decreased remarkably and specifically with increasing amounts of sorbents. Generally speaking, inactivation was complete at approximately 0.6 g of each additive. Both urease- and acid phosphatase activity were inactivated specifically. The inactivation of urease decreased in the sequence humic acid < montmorillonite < illite < pyrophyllite < halloysite < kaolinite < bentonite, whereas the following order of succession pyrophyllite < montmorillonite < bentonite < halloysite < kaolinite < illite was recorded with acid phosphatase. The yellow colour of humic acid excluded it from experiments with acid phosphatase. 2. No relationship could be found between the degree of inactivation and the cation exchange capacity (CEC) or the total surface area of the clays. However, nearly the same sequence of inactivation with the three enzyme systems was revealed, if their activity was related to the specific surface charge of the clay minerals. Apparently, both the total surface area as well as CEC are involved in the specific sorption of cells and enzymes. The possible mechanisms of sorption on clay surfaces are discussed. 相似文献
8.
Adsorption and desorption of salmon sperm DNA on four different colloidal fractions from Brown Soil and clay minerals were studied. The adsorption isotherms of DNA on the examined soil colloids and minerals conformed to the Langmuir equation. The amount of DNA adsorbed followed the order: montmorillonite?fine inorganic clay>fine organic clay>kaolinite>coarse inorganic clay>coarse organic clay. A marked decrease in the adsorption of DNA on organic clays and montmorillonite was observed with the increase of pH from 2.0 to 5.0. Negligible DNA was adsorbed by organic clays above pH 5.0. As for inorganic clays and kaolinite, a slow decrease in DNA adsorption was found with increasing pH from 2.0 to 9.0. The results implied that electrostatic interactions played a more important role in DNA adsorption on organic clays and montmorillonite. Magnesium ion was more efficient than sodium ion in promoting DNA adsorption on soil colloids and minerals. DNA molecules on soil colloids and minerals were desorbed by sequential washing with 10 mM Tris, 100 mM NaCl and 100 mM phosphate at pH 7.0. A percentage of 53.7-64.4% of adsorbed DNA on organic clays and montmorillonite was released, while only 10.7-15.2% of DNA on inorganic clays and kaolinite was desorbed by Tris and NaCl. The percent desorption of DNA from inorganic clays, organic clays, montmorillonite and kaolinite by phosphate was 39.7-42.2, 23.6-28.8, 29.7 and 11.4%, respectively. Data from this work indicated that fine clays dominate the amount of DNA adsorption and coarse clays play a more important role in the binding affinity of DNA in soil. Organic matter may not favor DNA adsorption in permanent-charge soil. The information obtained is of fundamental significance for the understanding of the ultimate fate of extracellular DNA in soil. 相似文献
9.
Extracellular enzymatic activities in soils are essential for the cycling of organic matter. These activities take place in multiphase environments where solid phases profoundly affect biocatalytic activities. Aspergillus niger is ubiquitous in soils; its β-glucosidase plays an important role in the degradation of cellulose, and therefore in the global carbon cycle and in the turnover of soil organic matter. However, the information on the interactions of this protein with soil minerals is very limited, and even less is known about their consequences for the hydrolysis of the natural substrate cellobiose. We therefore characterised the sorptive interactions of this enzyme with the soil minerals montmorillonite, kaolinite and goethite and quantified the resulting changes in the hydrolysis rate of cellobiose. Fractions of adsorbed protein, and the resulting catalytic activity loss, were lower for montmorillonite than for kaolinite and goethite at given experimental conditions; adsorption was 9.7 ± 7.3% for montmorillonite, 70.3 ± 3.1% for kaolinite and 71.4 ± 1.8% for goethite, respectively. Adsorption of the protein to the minerals caused a total decrease in the catalytic activity of 18.8 ± 3.4% for kaolinite and 17.9 ± 4.7% for goethite whereas it was not significant for montmorillonite. The average catalytic activity lost by the pool of adsorbed molecules was 26.8% for kaolinite and 25.0% for goethite. Both the amount of adsorbed protein and the resulting loss of catalytic activity were found to be independent of the specific surface areas yet were influenced by the electrical properties of the mineral surfaces. Under the experimental conditions, montmorillonite and kaolinite are negatively charged whereas goethite is positively charged. However, because of the adsorption of phosphate anions from the buffer, a charge reversal took place at the surface of goethite. This was confirmed by zeta (ζ)-potential measurements in phosphate buffer, revealing negative values for all the tested minerals. Indeed goethite interacted with the enzyme as a negatively charged surface: the amount of adsorbed protein and the resulting catalytic activity loss were very similar to those of kaolinite. Our results show that, even if an important fraction of β-glucosidase is adsorbed to the minerals, the catalytic activity is largely retained. We suggest that this strong activity retention in presence of soil minerals results from a selective pressure on A. niger, which benefits from the activity of the adsorbed, and thus stabilized, enzyme pool. 相似文献
10.
中国土壤胶体研究——ⅥⅡ.五种主要土壤的粘粒矿物组成 总被引：3，自引：0，他引：3
粘粒矿物对土壤特性和肥力的意义是众所周知的。土壤胶体的特性主要决定于粘粒矿物的类型及其数量。随着土壤科学研究的进展,粘粒矿物组成的分析工作,已由定性分析逐渐进入到定量分析。在粘粒矿物的鉴定中,X射线分析是一个很重要的手段,也有用来进行粘粒矿物的定量分析,但由于不同土壤中的矿物结晶程度差异很大,所以侧定的准确性较差。因此,在土壤粘粒矿物分析方面,X射线一般只能作为定性和半定量之用,其分析结果往往用“主导”“伴随”“较多~较少”等术语来表示。目前这种表示粘粒矿物组成的方法已不能满足研究工作的需要,何况不同学者的判读标准又很难一致。 相似文献
11.
The adsorption of the herbicide thiazafluron, 1,3-dimethyl-1-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)urea, by three smectites, illite, kaolinite, ferrihydrite and the clay fraction of an illitic soil (54.9% illite, 17.0% montmorillonite and 24.9% kaolinite) and a montmorillonitic soil (33.9% illite, 55.0% montmorillonite and 11.1% kaolinite) has been determined. Thiazafluron adsorbed on neither kaolinite nor iron oxide. The adsorption isotherms on smectites and illite conformed to the Freundlich equation. Values of Kf-obtained for smectites were larger than for the illite and increased as the layer charge of the smectite decreased. Desorption of thiazafluron on smectites was shown to be highly irreversible. Adsorption isotherms of thiazafluron on different homoionic montmorillonite samples suggest an important role of the exchangeable cations in the adsorption. Infrared spectra and X-ray diffraction analysis of the complexes of thiazafluron with homoionic montmorillonites indicated that thiazafluron adsorbs in the interlamellar space of the smectites, mainly by substitution of water molecules associated with the exchangeable cations through the carbonyl-amide group and formation of H-bonds or waterbridge between the NH group of the amide and the basal oxygens of the montmorillonite. The illitic soil clay adsorbed more of the herbicide than the montmorillonitic one did, suggesting that illite and montmorillonite may be present in soils in altered forms giving rise to different adsorption capacities from those of the pure minerals. 相似文献
12.
Soil mixtures containing 9% kaolinite, 9% montmorillonite, or no clay supplements were amended with 1% glucose and treated with H2SO4 to lower their bulk pH to levels ranging from 5.4 to 0.8. Acidification had little effect on soil respiration (CO2 evolution) until the pH was lowered below 3. Glucose was not degraded at approximately pH 2 but was degraded once the soil pH was raised to non-inhibitory levels, i.e. pH 4.1–4.3. When the soil pH was reduced to 1.4 or below, it was necessary to reinoculate the soil and raise the pH to a non-inhibitory level to obtain CO2 evolution. The addition of clay minerals, particularly montmorillonite, mitigated the toxic effect of H2SO4, especially at pH values below 3. The growth of Aspergillus niger, A. flavipes, Trichoderma viride and Penicillium brefeldianum was reduced or completely inhibited in soils acidified below pH 3.5. The addition of montmorillonite enhanced fungal growth under these acidic conditions, but kaolinite had no effect. 相似文献
13.
研究了土壤胡敏酸(Humic acid)对红壤和黄棕壤以及高岭矿和蒙脱矿粘粒分散的影响。研究结果表明：土壤HA对Na+饱和的土壤及矿物粘粒分散作用很大。用H2O2除去土壤有机质后,粘粒分散明显下降。然而,添加少量HA后,又能显著地提高粘粒的分散性。这种现象在两种土壤中,红壤表现更为突出。Na+饱和的高岭矿粘粒分散性很差,而蒙脱矿粘粒分散性很强,这与它们所带电荷量有关。但是,添加少量HA后,高岭矿粘粒分散性急剧提高,而蒙脱矿的变化却很小。试验结果进一步表明：有机质HA对土壤和矿物粘粒分散作用受矿物类型的影响。 相似文献
14.
本文研究了吸附性阳离子、电解质浓度和组成影响几种矿物和土壤吸附态磷的解吸的机理。结果表明,吸附性阳离子影响磷酸根解吸与离子桥有关。桥接静电场愈强,被束缚磷的释放就愈困难。电解质阳离子对磷酸根解吸的影响则取决于其对表面负电荷的屏蔽效应。阳离子电价高,屏蔽作用大,磷解吸就少。电解质浓度影响吸附态磷的解吸主要与表面电位的变化有关。当pH>PZC值时,提高电解质浓度降低表面负电位,从而减少磷的吸附;当pH<PZC时,提高电解质浓度则降低表面正电位,促进磷的解吸。磷酸根解吸盐效应零点(PPZSE)值一般都介于土壤或矿物样品吸附磷酸根前后测得的两个PZC值之间。不同浓度电解质溶液中磷解吸量之差与吸附层电位变化量(△ψx)呈正相关。 相似文献
15.
Analyses of the sorption of five polysaccharide cleaving soil enzymes by Na-homoionic clay minerals revealed a dependency on the cation exchange capacity of the clays: montmorillonite displayed the highest sorbing capacity, followed by palygorskite and kaolinite. Variation of the experimental conditions using cellulase and montmorillonite showed a maximum sorption at pH 4.8 and temperatures between 25°C and 45°C. Urea had no effect on the sorption, whereas humic acids and acetylation of enzymes lead to a decrease. No sorption was observed in the presence of bivalent cations. A discussion of possible binding mechanisms lead to the conclusion that interactions can be ascribed to van der Waals forces rather than to ionic reactions. It is assumed that the enzymes penetrate into the interlayers of montmorillonite, but not of palygorskite and kaolinite. 相似文献
16.
除草剂草甘膦在几种土壤和矿物上的吸附研究 总被引：5，自引：0，他引：5
通过批平衡实验考察了草甘膦在几种性质不同土壤和矿物上的吸附行为。研究发现土壤对草甘膦有较强的吸附能力，草甘膦在土壤上吸附量的大小与土壤理化性质密切相关。草甘膦在土壤和矿物上的吸附符合Freundlich吸附方程，其在土壤上的吸附常数K与土壤粘粒含量呈正相关，并随土壤氧化铁和氧化铝含量增加而增加，而与土壤的pH呈显著负相关。草甘膦在高岭石上的吸附量要比在蒙脱石上大，而草甘膦在金属离子饱和的蒙脱石和高岭石上的吸附研究结果表明，草甘膦在钠、钙、铁离子饱和的矿物上的吸附能力依次为Fe-蒙脱石〉Ca-蒙脱石〉Na-蒙脱石和Fe-高岭石〉Ca-高岭石〉Na-高岭石。 相似文献
17.
18.
[目的]探究伊毛缟石对蒙脱土和高岭土分散凝聚特性的影响,为水土保持和环境保护工作提供理论依据。[方法]采用浊度法测定黏土的分散性、离子交换法测定黏土电荷特性、电子显微镜观察等实验方法,将蒙脱土和高岭土溶液分别按一定比例混合伊毛缟石溶液,观察伊毛缟石对蒙脱土和高岭土分散凝聚特性的影响。[结果]伊毛缟石和蒙脱土的1∶1混合溶液,在全部pH值范围内保持凝聚;未脱铁处理的高岭土在pH值为5.9以下凝聚,在pH值为6.0以上分散,添加约5%的伊毛缟石使它的分散凝聚特性逆转。[结论]从微观上看,无论在酸性还是碱性条件下,伊毛缟石混合溶液都呈凝聚状态。酸性时,伊毛缟石的可变电荷和结晶性黏土矿物的永久电荷之间的引力形成凝聚;碱性时,伊毛缟石的表面变成中性形成凝聚。 相似文献
19.
Assessing the fixation and availability of sorbed phosphate in soil using an isotopic exchange method 总被引：3，自引：0，他引：3
An isotopic exchange method was used to characterize quantitatively the fixation and plant availability of phosphate previously sorbed by soils. In general, the exchangeability of the sorbed phosphate was much higher than its desorbability for both soils and clay minerals. Isotopic exchangeability of the sorbed phosphate increased with sorption saturation during the initial stage (15–60% saturation), but the increase was less with increasing saturation from 60–90% for all soils tested. Therefore a sorption saturation of 60% was recommended as the upper limit of P fertilization in terms of economical efficiency. For clay minerals, with increasing sorption saturation, the isotopic exchangeability of the sorbed P increased significantly for kaolinite and sesquioxides, but decreased for montmorillonite. Most of the phosphate sorbed by montmorillonite and kaolinite was found to be isotopically exchangeable, but only a small amount of the P sorbed by goethite could be exchanged. The P sorbed by Al oxide exhibited isotopic exchangeability between that of kaolinite and Fe oxide. The isotopically exchangeable phosphate pool could readily account for the P uptake of plants and the available P determined by some commonly used chemical methods, such as Olsen-P and Bray-P. 相似文献
20.
Thirty two soil samples from China were analyzed for exchangeable K before and after drying. Most soil samples were higher in exchangeable K after air-drying and ovendrying (60°C) than when wet. Soil clay minerals, especially clay-size mica, affected K released in air-dry and oven-dry samples. According to composition of clay minerals of air-dried samples, five classes were recognized. Soil samples with high mica and montmorillonite have the highest exchangeable K. Samples that contained higher kaolinite than mica had lower exchangeable K. Samples with higher kaolinite than quartz and mica had still lower exchangeable K. Samples of sandy soils contained very low exchangeable K. When quartz was the main mineral, the samples that had kaolinite and gibbsite as the main clay minerals had very low exchangeable K. The degree of weathering (weathering mean) bore an inverse relationship to the amount of K released on drying in air or at 60°C. Udults and Udalfs (Red Earths) of southeastern China, because of their high K release on being dried, are inferred to have received fine mica from the Western Desert dust rainout, reported to Liu et al. (1981). 相似文献