首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
The toxic effect of Ni, Cu, Ag, Cd, and Zn adsorbed to clay minerals on six fungal species was studied. In some cases the ions adsorbed to the clay were more effective as growth inhibitors than those in solution. This phenomenon was especially prominent with Cu and Ag. Though Ca was found to be non-toxic to the fungi, Ca-clay complexes inhibited fungal growth. It is postulated that clay may inhibit fungi through: (1) adsorptive effects when the cation is non toxic; and (2) direct heavy metal toxicity.  相似文献   

2.
The addition of fulvic acid to clay suspensions (kaolinite, illite or montmorrillonite) resulted in increased uptake of Cu, Pb, Cd, and Zn ions over the pH range 3 to 6, due to the limited solubility of one of the metal-fulvate species formed. At higher pH values, residual metal ion was retained in solution, instead of precipitating as hydroxy species. The amount of total metal ion found in solution at equilibrium was determined by the quantity and type of clay added; the amount of organic acid present; and to a lesser extent, pH. The behavior of the clay-fulvic acid systems differed from that observed using other organic materials such as gelatine, tannic acid or a humic acid.  相似文献   

3.
Profiles of semi-arid-zone soils in Punjab, northwestern India, were investigated for different forms of copper (Cu), including total Cu, diethylenetriaminepentaacetic acid (DTPA)–extractable Cu, soil solution plus exchangeable Cu, Cu adsorbed onto inorganic sites, Cu bound by organic sites, and Cu adsorbed onto oxide surfaces. When all soils were considered, total Cu content ranged from 7 to 37 mg kg?1, while DTPA-extractable and soil solution plus exchangeable Cu contents ranged from 0.30 to 3.26 mg kg?1 and from 0.02 to 0.43 mg kg?1, respectively. Copper adsorbed onto inorganic sites ranged from 0.62 to 2.6 mg kg?1 and that onto oxide surfaces ranged from 2.0 to 13.2 mg kg?1. The Cu bound by organic sites ranged from 1.2 to 12.2 mg kg?1. The magnitudes of different forms of Cu in soils did not exhibit any consistent pattern of distribution. Organic matter and size fractions (clay and silt) had a strong influence on the distribution of different forms of Cu. The content of all forms of Cu was generally greater in the fine-textured Alfisols and Inceptisols than coarse-textured Entisols. Soil solution plus exchangeable Cu, Cu held onto organic sites, and and Cu adsorbed onto inorganic sites (crystalline) had significant positive correlations with organic carbon and silt contents.The DTPA Cu was positively correlated with organic carbon, silt, and clay contents. Total Cu content strongly correlated with silt and clay contents of soils. Among the forms, Cu held on the organic site, water soluble + exchangeable Cu, and Cu adsorbed onto oxide surface were positively correlated with DTPA-extractable Cu. The DTPA-extractable Cu and soil solution plus exchangeable Cu seems to be good indices of Cu availability in soils and can be used for correction of Cu deficiency in the soils of the region. The uptake of Cu was greater in fine-textured Inceptisols and Alfisols than coarse-textured Entisols. Among the different forms only DTPA-extractable Cu was positively correlated with total uptake of Cu.  相似文献   

4.
ABSTRACT

A greenhouse experiment was conducted to determine the bioavailability of copper (Cu) in clay loam and sandy clay loam soil. Lettuce (Lactuca sativa) and spinach (Spinacia oleracea) were grown in pots for 45 d. When mature, plants were treated for 15 additional days with 0, 100, 250, 500, or 1000 mg Cu kg?1 as CuSO4·5H2O. After harvest, Cu in soils and plant tissues was determined. In soils, applied Cu raised total and EDTA-extractible Cu. Results also revealed that the amounts of Cu extracted from sandy clay loam soil (80%) were higher than those extracted from clay loam soil (70%). In plants, increasing soil Cu concentration increased plant concentration of the metal. Plant species vary in their capacity for Cu accumulation: Lettuce has a relatively higher potential for Cu uptake and translocation than does spinach. Cu accumulation also differs among plant organs. In lettuce, metal accumulation is higher in roots than in shoots, where 60% to 80% of the total Cu of the plant is located in the roots. However, in spinach, there is no significant difference in Cu content between roots and shoots. The transfer of the metal from soil to plant is higher for plants grown on sandy clay loam soil. For a given rate of applied Cu, metal content in plant tissues is higher on sandy clay loam soil due to its higher transfer coefficient (CT) from soil to plant. Nevertheless, all crops studied showed a positive linear relationship between extractible soil Cu and plant Cu.  相似文献   

5.
The extent to which heavy metal ions (Cu, Pb, Zn, Cd) are removed from aqueous solution by clay suspensions (kaolinite, illite or montmorillonite) has been shown to vary with the nature of the clay, solution pH, concentration of competing cations, and the nature (and concentration) of any ligands present. The amount sorbed increases gradually with pH until the threshold value for formation of sparingly soluble hydroxy complexes is reached. The affinity order for divalent cations, and the nature of the sorption process also appear to vary with clay type.  相似文献   

6.
The amount of metal ion sorbed by the solids increased with increasing pH over the range 3 to 6, and with mixtures of clay-cellulose or illite-humic acid the uptake corresponded to the direct addition of individual substrate adsorption values. When the humic acid samples were admixed with Na+-form kaolinite or montmorillonite, there was some reduction in adsorption, attributable to component interactions, and this effect was most marked in the presence of Cu and Zn ions. In alkaline media there was competition between the ability of the organic material to form soluble metal humates and the tendency of the clays to strongly retain the sparingly soluble metal hydroxy species formed at pH > 6. In most systems studied retention by the solid phase predominated. In the presence of tannic acid there were distinct pH regions in which the four metal ions formed compounds of limited solubility, with the pH for maximum precipitation ranging from 4.5 (Cu) to 7 (Cd). The introduction of clay suspensions increased the amount precipitated/sorbed in these pH regions. The amount of Cu, Pb, Zn or Cd retained by mixed suspensions varied markedly with pH, nature of the clay and the chemical nature of organic components.  相似文献   

7.
Adsorption and release are the most influential reactions controlling zinc (Zn), manganese (Mn) and copper (Cu) availability in soils. Characteristics of native Zn, Mn and Cu release by ethylenediaminetetraacetic acid (EDTA) in two calcareous soils for periods from 1 min to 24 h were studied. The pattern of Zn, Mn and Cu release from both soils fitted well with power function, Elovich and parabolic diffusion models. The magnitude and rate of release was greatest for Mn, followed by Zn and Cu, respectively. This trend suggests a higher ability of the studied soils to replenish soil solution Mn, compared with Zn and Cu. The results showed that higher Mn release in clay soil compared with sandy loam soil was considerably related to higher initial Mn release rates in the former compared with the latter. However, Cu release rates of the two soils at initial times were not significantly different. Higher Cu release in clay soil was, therefore, attributed tohigher Cu release rates at subsequent time intervals. It is assumed that the different Zn release rates of these soils were due to consistent differences in Zn release rates throughout the release periods.  相似文献   

8.
Heavy metals are present as various chemical species in soil environments. Chemical species of heavy metals determinate their behavior in soil, so they must be more important concern than total contents in treating problems about heavy metal polluted soil. Microbial activity is thought to be one of the factors that affect chemical speciation of heavy metals. Although some possible microbial mechanisms have been suggested, their effects on heavy metals have not previously been thoroughly studied. In this study, we investigated whether microorganisms contribute to the fractionation of Cu in a forest soil. Copper-enriched, sterilized forest soil samples were buried at their places of origin, and subsamples were collected for analysis 3, 10, 17, 30, 60, and 90 days after burial. Tessier’s sequential extraction was employed to analyse Cu fractionation. Until two months after burial, the added Cu remained nearly unchanged. But a dramatic change was found in soil subsamples after three months. In both the A and B horizons, the carbonate fraction of Cu increased and the residual fraction decreased. We also found that clay minerals and persistent organic matter are important binding substances of Cu in the residual fraction. The change from residual to carbonate fraction could be caused by microbial activity.  相似文献   

9.

A pot-experiment to determine the Cu upper critical level (UCL) in some representative Chilean soils using alfalfa plants as indicators was carried out at La Platina Experimental Station from 1988 to 1989. Those soils having an abundant clay fraction dominated by 2:1 minerals and/or high organic matter contents retained Cu very strongly showing low Cu toxicity and high Cu-UCL. Reversely, those soils having few clay minerals or abundant ones dominated by 1:1 minerals and/or low organic matter contents showed weak Cu retention giving pronounced toxic effects reflected by low Cu-UCL values. Growth depletion was related to increased Cu content in the aerial biomass reflecting an additional Cu uptake by roots and its translocation into the aerial part of the plants; normal plants were associated to normal Cu contents in tissues.

  相似文献   

10.
A pot experiment was performed to investigate the effect of cobalt (Co) and copper (Cu) nutrition on nodulation, nodule activity and growth of Lablab purpureus plants growing in sandy clay loam soil collected from Toshka region in south of Egypt. The pots were given nutrient solution only once with addition of increasing levels of cobalt and copper (50, 100, 150 and 200 μg) as cobalt or copper sulfate solution. The present study has provided a new insight into the effect of cobalt and copper on nodulation and nodule physiology of Lablab purpureus (L.) Sweet (kashrangeeg) that has not yet been examined. Thus, the present work suggest that Co and Cu application is essential for the enhancement of nodulation, nodule activity and growth of Lablab purpureus plants growing in sandy clay loam soil deficient for theses microelements.  相似文献   

11.
Sorption of antibiotics to clay minerals is a key process controlling their transport and fate in environment. In this study, the effects of pH, ionic strength, and Cu(II) on ofloxacin (OFL) sorption to kaolinite were investigated by batch sorption experiments. The results of sorption edge experiments suggested that OFL sorption to kaolinite was pH and ionic strength dependent. Cation exchange was a major contributor to the sorption of OFL+ to kaolinite. The decreased OFL sorption with increasing ionic strength indicated the formation of outer-sphere complexation. When solution pH was lower than 7.0, Cu-OFL complexes facilitated OFL sorption through electrostatic attraction or formation of kaolinite-Cu-OFL and kaolinite-OFL-Cu ternary surface complexes. However, existence of free Cu(II) cation in solution competed for sorption sites, and thus suppressed OFL sorption. When solution pH was higher than 7.0, Cu(II) existed as Cu(OH)2, and the Cu-OFL complexes in aqueous phase and solid phase (precipitation) enhanced OFL removal efficiency from solution. The results imply that Cu(II) effects should be taken into account in the evaluation of OFL mobility in environment.  相似文献   

12.
We studied the properties of the soluble and dispersed compounds of Cu, Mn, Co, Ni, Pb, Zn, and Cd formed by the action of aerobically decomposing plant matter on the respective metal oxides. The metals were mobilized partly in association with colloidal humified organic matter, and partly in true solution as complexes that seemed to be anionic. In the presence of a clay soil there was no net mobilization of colloidally bound Cu, but the dialysable Cu complex was not appreciably sorbed by the mineral colloids and was leached from the reaction mixture. The metals were not precipitated under alkaline conditions from the dialysable complex forms. Material with similar complexing properties was found in the dialysable fractions of a soil organic matter extract, of water squeezed from a raw peat, and of laboratory lysimeter solutions from a podzol under Calluna. Below about pH 6 the exchange of Cu on a soil clay was not affected by the presence of colloidal decomposition products of lucerne. With Co, Ni, and Zn the corresponding pH value was about 4, and the critical value for Cu in the presence of colloidal soil organic matter was also about 4. Below these values the metal and organic matter sorption curves were diametrically opposed so that under these conditions Cu is apparently not strongly bonded to colloidal organic matter.  相似文献   

13.
The adsorption of copper by individual soil components (organic matter fractions, oxides and clay minerals) was examined at equilibrium solution concentrations of copper within the range found in natural soils, the distribution of copper between solution and solid phases being measured by means of labelling with radioactive 64Cu. At these low solution concentrations it was found that the copper adsorption isotherms were essentially linear. The oxides and organic materials adsorbed the greatest amounts of copper. The concentration of copper in natural soil solutions will be controlled by these materials to a far greater extent than by the clay minerals, the influence of which may be negligible in some soils. Solution concentrations of copper are relatively unaffected by both the background concentration of major cations and by changes in pH within the ionic strength and pH range found in normal agricultural soils. Copper adsorption studies with humic and fulvic acids showed that total solution copper concentrations could be greatly enhanced above the equilibrium levels for ionic copper by the presence of soluble organic complexes. The importance of taking into account the presence of such copper complexes in soil copper studies is emphasised.  相似文献   

14.
Copper adsorption and desorption under acid conditions by soil clay fractions separated from Vertisol, Planosol and Gleyic Acrisol has been studied in 0.01 M Ca(NO3)2. A Freundlich equation was appropriate to describe Cu adsorption. Within the range of 150 to 2600 mg of copper per kg of soil clay fraction the proportions of Cu not displaced during 5 successive 48-hour desorptions with 0.01 M Ca(NO3)2 decreased with increasing adsorption density and at the lower pHs. The proportions ranged from as high as 0.98 in th case of the Vertisol clay (pH 5.3) to as low as 0.12 (88% desorption) in the Planosol clay (pH 4.5). Measurement of separation factors (ga Cu/Ca) showed that the preference of the clay surface for Cu over Ca decreased in the order: Gleyic Acrisol > Planosol > Vertisol. A considerable amount of sorbed copper could be solubilized by decreasing pH values to 4 when in the Planosol clay 39% was desorbed and 45% was desorbed in the Gleyic Acrisol clay.  相似文献   

15.
Abstract

Copper (Cu) is bound strongly to organic matter, oxides of iron (Fe) and manganese (Mn), and clay minerals in soils. To investigate the relative contribution of different soil components in the sorption of Cu, sorption was measured after the removal of various other soil components; organic matter and aluminum (Al) and Fe oxides are important in Cu adsorption. Both adsorption and desorption of Cu at various pH values were also measured by using diverse pasture soils. The differences in the sorption of Cu between the soils are attributed to the differences in the chemical characteristics of the soils. Copper sorption, as measured by the Freundlich equation sorption constants [potassium (K) and nitrogen (N)], was strongly correlated with soil properties, such as silt content, organic carbon, and soil pH. The relative importance of organic matter and oxides on Cu adsorption decreased and increased, respectively, with increasing solution Cu concentrations. In all soils, Cu sorption increased with increasing pH, but the solution Cu concentration decreased with increasing soil pH. The cumulative amounts of native and added soil Cu desorbed from two contrasting soils (Manawatu and Ngamoka) during desorption periods showed that the differences in the desorbability of Cu were a result of differences in the physico‐chemical properties of the soil matrix. This finding suggests that soil organic matter complexes of Cu added through fertilizer, resulted in decreased desorption. The proportions of added Cu desorbed during 10 desorption periods were low, ranging from 2.5% in the 24‐h to 6% in the 2‐h desorption periods. The desorption of Cu decreased with increasing soil pH. The irreversible retention of Cu might be the result of complex formation with Cu at high pH.  相似文献   

16.
中南地区淋溶土的层间羟基物矿物   总被引：1，自引：0，他引：1  
李学垣  徐凤琳  HuangPM 《土壤学报》2002,39(3):326-333
将北纬 3 0°～ 3 2°亚热带花岗岩发育的两个淋溶土B层黏粒样分别用连二亚硫酸钠—柠檬酸钠—重碳酸钠 (DCB)溶液溶提处理和经DCB溶液处理后再用柠檬酸钠溶液溶提处理。从上述处理后样品的X射线衍射图谱中可看出 :供试土壤的膨胀性矿物层间有羟基物质 ,它们能被DCB溶液—柠檬酸钠溶液所溶解提取 ,含羟基物质的黏土矿物主要来源于蛭石 ,少量来自蒙皂石。DCB溶液—柠檬酸钠溶液处理前后黏粒红外差分光谱上显示的 980～ 970cm- 1 ,91 0～940cm- 1 吸收带 ,标志着供试土壤膨胀性矿物层间含有羟基铝硅酸和羟基铝离子。从而首次揭示了中国中南地区淋溶土的膨胀性矿物层间有羟基铝硅酸。  相似文献   

17.
The impact of slope aspect and gradient on the contents and distribution of heavy metals (Mn, Cu, Zn, Co, Ni, Pb, and Cd) in the profiles of ordinary chernozem (Haplic Chernozems) was studied in Kursk oblast. Slope aspect was found to be a significant factor controlling the distribution of most of the bulk, mobile, and acid-soluble compounds of heavy metals, whereas the position on the slope (slope gradient) did not exert a significant influence on the distribution of elements. Bulk compounds of Co, Ni, Pb, and Cd showed the eluvial type of distribution in the soil profiles along with accumulation in the lower horizons. Distribution patterns of the mobile Cu, Co, Ni, Pb, and Cd were similar to those of the bulk ones. The latter phenomenon may be attributed to the high content of carbonates, an increased content of clay, and some alkalization of the soil solution in the lower horizons.  相似文献   

18.
Deficiency of micronutrients is increasing in crop plants in recent years in Oxisols and Ultisols in the tropics. The predominant soils in the coastal tablelands of Brazil are Ultisols and Oxisols, with low cation exchange capacity and kaolinitic clay mineralogy. Soil copper (Cu), manganese (Mn), and zinc (Zn) extracted by the Mehlich 1 solution, currently used in the regional soil-testing laboratories, were compared with those extracted by the Mehlich 3 and diethylenetriaminepentaacetic acid (DTPA) solutions in a greenhouse experiment with 10 soil samples (0–20 cm deep) collected from representative Ultisols and Oxisols from various locations in the region. Corn was grown as a test crop, and its dry matter and micronutrient uptake was measured at 30 days of growth. Soil Cu, Mn, and Zn extracted with the three solutions were significantly correlated (0.65–0.95 range for r values), with the Mehlich 3 solution extracting greater quantities than the Mehlich 1 and DTPA solutions. Zinc and Cu taken up by corn plants were significantly related to their soil-extractable levels measured at harvest with all three of the solutions, except for Zn DTPA. However, similar relations between plant uptake and soil extractable Mn were poor, except for DTPA extracting solution.  相似文献   

19.
Copper adsorption studies were conducted with 13 neutral to calcareous-alkaline soils. The data followed a Langmuir isotherm with two linear parts at low (part 1) and high (part 2) concentration of Cu in equilibrium solution. The ?pCu + 2pOH’? values show that part 1 and 2 stem largely from adsorption and precipitation reactions of Cu, respectively. The bonding energy and differential buffering capacity were significantly higher for part 1 while adsorption maximum and supply parameter were significantly higher for part 2 of the isotherms. Carbonate content, soil pH, organic matter, CEC and clay content were in that oder the predominant factors in elevating adsorption maximum, bonding energy coefficient and differential buffering capacity as well as decreasing supply parameter of soils. However, soil organic matter was the major determinant of strength of Cu adsorption. Copper potentials, adsorption maximum and differential buffering capacity were significantly correlated with dry matter production and Cu uptake in maize. The parameters of intensity factor predicted better the variation in yield and Cu uptake than the conventional soil test methods.  相似文献   

20.
Abstract

The profile distribution of total, DTPA‐ and 0.1N HCl‐extractable Cu was determined in 11 Nigerian soil profiles formed from various parent materials including the coastal plain sands, shales, basalt, granite and banded gneiss.

Total Cu ranged from 7 to 72 ppm with a mean of 35 ppm0 The soils formed from basalt had the highest values while those on coastal plains had the least content. Generally, there was a higher content in the subsoils than in the surface horizons. The total Cu significantly correlated with percent clay and the free oxide contents of Fe and Mn.

DTPA ‐ and 0.1N HCl‐extractable Cu ranged from 0.08 to 2.81 ppm and 0.10 to 7.78 ppm, respectively. Soils on metamorphic rocks gave the highest values of DTPA‐extractable Cu. The DTPA‐extractable Cu ‐was only related to pH but the acid extractable Cu was associated with total Cu, clay, free Fe2O3 and MnO2 contents.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号