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1.
Field experiments were conducted on rice (cv ‘IET 4094’) in an Aeric endoaquept (pH 7.2) to evaluate the various zinc (Zn) extractants in lowland rice soil under the influence of Zn sulfate and chelated Zn. The diethylenetriaminepentaacetic acid (DTPA), 0.1 N hydrochloric acid (HCl), and 0.05 N HCl‐extractable Zn concentrations in soil increased initially up to the Z29 stage of crop growth when Zn was applied as a single basal source, being greater with Zn ethylenediaminetetraacetic acid (Zn‐EDTA) compared to zinc sulfate (ZnSO4) application. Among the various extractants, the performance of 0.1 N HCl in extracting Zn was better than the other two extractants and followed the trend 0.1 N HCl > 0.005 M DTPA > 0.05 N HCl. The greatest increase in grain and straw yield of rice was 37.8 and 20.4%, respectively, over the control in the treatment T7 (1 kg Zn ha?1 as Zn‐EDTA at basal).  相似文献   

2.
Desilication and leaching are processes that accompany plinthilization, leading to nutrient depletion. Soils from 12 profiles in a plinthitic landscape were analyzed for extractable micronutrients [iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu)]. Soils of the landscape from crestal to lower‐slope position contain plinthite in the profile, whereas those of the valley floor are devoid of plinthite. The micronutrients were extracted using diethylenetriaminepentaacetic acid (DTPA) and 0.1 M hydrochloric acid (HCl). The results showed that 0.1 M HCl extracted more of the micronutrients than DTPA. The DTPA‐extractable Fe, Zn, Mn, and Cu in all the soils ranged from 1.15 to 12.44 (mean, 3.69); 0.71 to 2.75 (mean, 1.86); trace 12.44 (mean, 3.35), and trace 3.76 (mean, 0.63) mg kg?1, respectively. The DTPA‐extractable micronutrient contents were generally greater than the critical available level (4.5 mg kg?1 for Fe, 0.8 mg kg?1 for Zn, 1.0 mg kg?1 for Mn, and 0.2 mg kg?1 for Cu). The 0.1 M HCl‐extractable micronutrients in the landscape ranged from 8.00 to 30.40 (mean, 15.19); 0.30 to 6.49 (mean, 1.35); 1.00 to 27.20 (mean, 7.74); and 0.26 to 15.0 (mean, 2.77) mg kg?1 for Fe, Zn, Mn, and Cu, respectively. Both DTPA‐ and 0.1 M HCl‐extractable micronutrients were generally lower in the plinthitic horizons than in the nonplinthitic horizons and higher in the Ap than the subsoil horizons. Correlation analysis showed a significant relationship between DTPA‐Fe and DTPA‐Mn, Cu, and organic carbon (r = 0.913**, 0.411**, and 0.385**). There was a significant and positive relationship between 0.1 M HCl‐extractable Mn and organic carbon (C), total nitrogen (N), and available phosphorus (P) (r = 0.413**, 0.337**, and 0.350**, respectively).  相似文献   

3.
A pot experiment was conducted to investigate the effect of chromium compost (0, 10, 30, and 50%) on the growth and the concentrations of some trace elements in lettuce (Lactuca sativa L.) and in the amended soils. Compost addition to the soil (up to 30%) increased dry matter yield (DMY); more than 30% decreased DMY slightly. The application of compost increased soil pH; nitric acid (HNO3)–extractable copper (Cu), chromium (Cr), lead (Pb), and zinc (Zn); and diethylenetriaminepentaacetic acid (DTPA)–, Mehlich 3 (M3)–, and ammonium acetate (AAc)–extractable soil Cr and Zn. The addition of Cr compost to the soil increased tissue Cr and Zn but did not alter tissue cadmium (Cd), Cu, iron (Fe), manganese (Mn), nickel (Ni), and Pb. The Cr content in the lettuce tissue reached 5.6 mg kg?1 in the 50% compost (326 mg kg?1) treatment, which is less than the toxic level in plants. Our results imply that compost with high Cr could be used safely as a soil conditioner to agricultural crops.  相似文献   

4.
The use of animal waste for a soil amendment is a viable option for waste management. For safe and sustainable management of waste, it is important to assess the concentrations of heavy metals (HM). An experiment was conducted to compare metals [copper (Cu), zinc (Zn), and manganese (Mn)] in cow manure (CM), duck litter (DL), poultry litter (PL), and poultry litter ash (PLA) using eight extraction solutions. Extractability of HM was highly dependent upon the type of waste as well as extracting agent. Manures differed for the release of HM in the order of PL > DL > CM. Marked decreases in extractable trace elements were observed after ashing of PL irrespective of extraction method. Except for water, extractions released HM in the order of Mn > Cu > Zn. For Zn and Mn, the amount extracted varied in the order 1 M nitric acid (HNO3) > 0.1 M HNO3 > 0.01 M HNO3 ≈ ethylenediaminetetraacetic acid (EDTA) > ammonium nitrate (NH4NO3) > calcium chloride (CaCl2) > ammonium acetate (NH4OAc) > H2O in PL and PLA. Peak concentration of Cu was achieved in 1 M HNO3 solution and the lowest Cu was found in NH4OAc solution. On the basis of these results, the low extractability of HM in ash could suggest that the use of burned PL would be less of a water-pollution problem in the fields.  相似文献   

5.
Abstract

The present work was undertaken to obtain information on the effectiveness of extractants used for soil testing in Estonia and in Finland and to evaluate the suitability of the Finnish methods for use with Estonian soils. The sample material involved 86 soils and winter wheat (Triticum aestxvum L.) shoots collected from farmers’ fields in Estonia. The extractants used in Estonia were double lactate (DL) for phosphorus (P) and potassium (K), ammonium lactate (AL) for calcium (Ca) and magnesium (Mg), 1N HCl for copper (Cu), manganese (Mn), and zinc (Zn), ammonium oxalate (AO) for molybdenum (Mo) and 1N HNO3 for cadmium (Cd) and lead (Pb). In Finland, acid ammonium acetate (AAAc) was used for P, K, Ca, and Mg determination, and acid ammonium acetate‐EDTA (AAAc‐EDTA) for Cu, Mn, Mo, Zn, Cd, and Pb. The order of magnitude of extractable concentrations for these elements was: PDL > PAAAc, KDL < KAAAc, CaAL < CaAAAc, MgAL> MgAAAc, CuHCl > CuAAAc‐EDTA, MnHCl, > MnAAc‐EDTA, ZnHCl < ZnAAAc‐EDTA, MoAO > MoAAAc‐EDTA, CdHNO3 > CdAAAc‐EDTA, and PbHNO3 > PbAAAc‐EDTA. Correlations between results of respective methods for determining macronutrients were high (r ≥ 0.9). In the case of Cu, Mn, Mo, Zn, Cd, and Pb r values ranged from 0.5 to 0.8 due to difficulties in determining low concentrations. A statistically significant correlation between concentrations of elements in soil and in wheat shoots only existed for few elements. The DL extractable P and K correlated better than those for the AAAc method, and coefficients for the DL method were 0.29 and 0.31, respectively. This indicates that the DL method is better suited to Estonian soils than the AAAc method. In the case of Cu, Mn, Mo, and Zn, no method preference was found.  相似文献   

6.
Abstract

The effect of grinding on soil extraction was determined for two soil fractions and three extractants. Arsenic (As), beryllium (Be), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), vanadium (V), and zinc (Zn) were extracted by aqua regia and 2 M nitric acid. Mehlich 3 extractant was used for determination of potassium (K), magnesium (Mg), calcium (Ca), phosphorus (P), iron (Fe), and aluminum (Al). One hundred forty‐seven agricultural soil samples representing all major soil types, climatic regions, and proportions of agronomic cultures in the Czech Republic were collected for the study. Particle size fractions smaller than 2 mm and smaller than 0.150 mm were chosen for investigation. Extraction of elements by aqua regia was similar for both size fractions of soil. Cold 2 M nitric acid is a weaker extractant than aqua regia, and a statistically significant increase in extractable Be (5%), Cd (6%), Co (11%), Cu (5%), Ni (5%), and V (2%) was measured with the finely ground soils. An increase for the finer fraction for K (10%) and Mn (25%) was found for Mehlich 3. A more complex nonlinear relationship was found for Mehlich 3 extractable Al and Fe. This was probably caused by a more intensive re‐adsorption of Fe and Al to the finely ground soils.  相似文献   

7.
Abstract

A study was carried out to investigate the status of four micronutrients, iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn), and five other trace elements, cobalt (Co), chromium (Cr), nickel (Ni), lead (Pb), and strontium (Sr), in paddy soils of Bangladesh. Soil samples were digested by hydrofluoric acid (HF)‐nitric acid (HNO3)‐perchloric acid (HClO4) for determination of total contents of the nine elements, while DTPA, ASI and 0.1 Mhydrochloric acid (HC1) methods were used for determination of available Fe, Cu, Mn, and Zn. Total trace element contents were found to vary with physiography on which soils are distributed. In general, Ganges Tidal Floodplain soils had the highest content, whereas terrace soils had the lower content. Among the soil properties examined, clay content had a good relation with total trace element contents in the topsoil, except for Sr. Based on the variation with physiography or clay content, the nine trace elements could be grouped into six groups: Cu, Fe and Zn, Pb, Co and Cr and Ni, Mn, Sr. According to the extractable levels of four micronutrients, Bangladesh paddy soils had the medium to optimum amounts of Fe and Cu, but were deficient sporadically in Mn and extensively in Zn. It was indicated that paddy soils of Bangladesh are yet to be polluted with heavy metals.  相似文献   

8.
Twenty surface (0–15 cm) samples of acidic soils were analyzed for water soluble (WS), exchangeable (EX), lead displaceable (Pb-disp.), acid soluble (AS), manganese (Mn) oxide occluded (MnOX), organically bound (OB), amorphous Fe oxide occluded (AFeOX), crystalline iron (Fe) oxide occluded (CFeOX) and residual (RES) fractions of Mn, and also for extractable Mn in some common soil extractants: (diethylenetriaminepentaacetic acid (DTPA) (pH 7.3), DTPA (pH 5.3), AB-DTPA (pH 7.6), Mehlich-3 (pH 2.0), Modified Olsen, 0.005 M calcium chloride (CaCl2), 1 M magnesium chloride (MgCl2) and ion exchange resins. The WS-Mn fraction showed a significant and positive correlation with Mn extractable in DTPA (pH 5.3) and AB-DTPA (pH 7.6), while both WS-Mn and EX-Mn fractions correlated significantly and positively with Mn concentration and uptake by maize plants grown in these soils. The AB-DTPA (pH 7.6) and DTPA (pH 5.3) appeared suitable to assess the availability of Mn in acidic soils.  相似文献   

9.
Abstract

Wetland soils (hydric soils) are unique in their chemical characteristics compared to upland soils. It is known that they are capable of removing a variety of wastes from polluted water entering the wetland including metals and potentially toxic heavy metals. When these metals are determined in wetland soils, it is necessary to use the proper chemical extractant(s). Four commonly used chemical extractants (Mehlich 1, Mehlich 3, 0.1M HCl, and DTPA) for soil fertility evaluation were selected to measure metal concentrations of three different wetland soils/spoils. Soil samples were collected from the constructed wetland cells which were lined with Abernathy silt loam topsoil and two different mine spoil materials [collected from active coal strip‐mined sites in Alabama (pH 5.9) and Tennessee (pH 3.2)]. Mehlich 3 extracted the most zinc (Zn), iron (Fe), manganese (Mn), calcium (Ca), magnesium (Mg), potassium (K), sodiumm (Na), and aluminum (Al), while 0.1M HC1 extracted more cadmium (Cd), copper (Cu), and lead (Pb). Extractants followed the same trend in removing quantities of the metals from the three soil/spoil materials, with DTPA generally extracting the least amount of the metal (the trend was Mehlich 3 > 0.1N HCl > Mehlich 1 > DTPA). However, DTPA removed larger quantities of metals from Tennessee spoil compared to Alabama spoil and topsoil, suggesting the higher effectiveness of DTPA under acidic conditions. Metal concentrations in plant tissue did not show a definite trend in correlation with metals extracted by the four chemical extractants.  相似文献   

10.
Abstract

Alfisols, Vertisols, Inceptisols, Aridisols, Mollisols, and Entisols were sampled (0–30 cm) from 32 locations across Ethiopia. The soils were analyzed for copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) contents using 0.005 M diethylene triamine pentaacetic acid (DTPA), 0.05 M hydrochloric acid (HC1), and 0.02 M ethylene diamine tetraacetic acid (EDTA) extractants. EDTA extracted more of each micronutrient than DTPA, which extracted greater amounts than HC1. The quantities of EDTA and DTPA‐extractable micronutrients were significantly correlated, and were in the order: Mn>Fe>Cu>Zn. The order of HCl‐extractable micronutrients was Mn>Fe>Zn>Cu. Micronutrient contents of Mollisols, Vertisols, and Alfisols were usually greater than those of the other soils, and Entisols usually had the lowest micronutrient contents. The contents were mostly positively correlated with clay and Fe2O3 contents, but negatively correlated with soil pH and A12O3contents. While comparison of DTPA‐ and EDTA‐extractable micronutrients with critical levels showed that most soils had adequate amounts of the micronutrients for crops, the amounts extracted by HC1 were below critical levels in most soils. Since the critical levels that were used in the comparisons were not established in Ethiopia, calibration of the soil contents of these micronutrients with crops grown in Ethiopia is required to identify the most suitable extractant(s).  相似文献   

11.
Abstract

The relative effectiveness of Mehlich I (.025N H2SO4 + .05N HCl) and Mehlich III (0.2N CH3COOH + 0.25N NH4NO3 +.015N NH4F + .013N HNO3 + .001M EDTA) extractants as predictors of Mn, Cu and Zn uptake was assessed in a greenhouse experiment with four Delaware soils. The soils were adjusted to eight pH levels by addition of Ca(OH)2 or elemental S, and received comparable amounts of Mn, Cu and Zn as either (1) MnSO4 + CuSO4 + ZnSO4 or (2) Poultry Manure. Mehlich 1 and III extractable Mn and Zn, but not Cu, were well correlated in most instances. Excellent correlations were obtained between Mn uptake and Mehlich I and Mehlich III extractable Mn, for all soils and sources. In general, however, neither Zn nor Cu was found to correlate well with plant uptake. Based on this study, conversion to Mehlich III, as a routine soil test extractant for micronutrients, would not result in a significant improvement over the currently used Mehlich I extractant.  相似文献   

12.
Abstract

In this study, a new parallel and sequential extraction procedure was proposed to investigate the solubility of metals [cadmium (Cd), zinc (Zn), copper (Cu), and nickel (Ni)] and their association with soil components in naturally metal‐rich soils of Norway. Two different soils, alum shale (clay loam) and moraine (loam), developed on alum shale minerals were used. Each soil had two pH levels. For parallel and successive extractions, H2O, 0.1M NH4OAc (soil pH), 0.3M NH4OAc (soil pH), 1M NH4OAc (soil pH), and 1M NH4OAc (pH 5.0) were used. A significant amount of Cd was extracted by NH4O Ac related to concentration of NH4OAc in the extracting solution. The amounts of Zn, Cu, and Ni extracted by these reagents were almost negligible except with 1M NH4OAc (pH 5.0). Thus these metals were strongly bound to soil components. A seven step sequential extraction procedure was applied to evaluate the association of metals with soil constituents. The extractions were performed sequentially by extracting the soil with reagents having an increasing dissolution strength: 1M NH4OAc (soil pH), 1M NH4OAc (pH 5.0), 1M NH2OH.HCl (in 25% HOAc), 1M NH2OH.HCl (in 0.1M HNO3), 30% H2O2 (in 0.1M HNO3), 30% H2O2 (1M HNO3), and aqua regia. In both soils at both pH levels investigated, appreciable percentages of total Cd (20–50%) were found associated with the NH4OAc extractable fraction (mobile fraction). For Zn, Cu, and Ni, the percentage of total metal extracted with NH4OAc was low (<4%), but it increased significantly by introducing a reducing agent (NH2OH.HCl). The NH2OH.HCl‐extractable fraction was the greatest fraction (>60%) for all four metals examined. These results suggest that among the metals studied, only Cd was easily desorbed from soil and should be considered mobile and potentially bioavailable. Other metals (Zn, Cu, and Ni) were strongly associated with the soil components and should be considered less available to plants. Using the sequential fractionation technique as a measure of availability, mobility and potential bioavailability of these four metals in the alum shale soils were: Cd>Zn>Ni>Cu.  相似文献   

13.
In the present study, a laboratory experiment was designed to compare the 0.01 M calcium chloride (CaCl2) and diethylenetriaminepentaacetic acid (DTPA) extraction methods for their ability to predict cadmium (Cd), copper (Cu), iron (Fe), Manganese (Mn), nickel (Ni), and zinc (Zn) availability and mobility in five calcareous soils. The soils were spiked with different amounts of metals (0, 50, 100, 200, and 400 mg kg?1) both in binary (Cu and Zn; Ni and Cd; Fe and Mn) and in multi-systems (Cd, Cu, Fe, Mn, Ni, and Zn) and incubated for 1 months at field capacity. In metal-spiked soils, both extraction methods showed a linear relationship of extractable to total metals for all soils. The fraction of total metals extracted by DTPA was much higher than the fraction extracted by CaCl2, which was attributed to the formation of soluble metal-complexes in the complexing extracts calculated by the Visual Minteq program. DTPA extraction method showed higher selectivity for Cu over other metals both in binary and in multi-systems. Different order of metals extractability was found in binary and multi-systems for both extraction methods. Solid/solution distribution coefficient (Kd) was calculated by the ratio of the solid phase to soil solution concentration of metals extracted by CaCl2 or DTPA extraction methods. Both in binary and in multi-systems, the average Kd (l kg?1) of metals by soils were in the order of Mn (5398) > Fe (4413) > Zn (3376) > Cu (2520) > Ni (969) > Cd (350) in the CaCl2-extractable metals and Fe (35) ≥ Ni (34) > Zn (18) > Mn (11.2) > Cu (6.3) > Cd (4) in the DTPA-extractable metals. Results showed that among the six studied metals, Cd had the lowest Kd, implying a relative higher mobility in these calcareous soils. The Visual Minteq indicated that in the CaCl2-extraction method and in both binary and multi-systems the dominant species for Cu, Mn, Ni, and Zn were Cu2+, Mn2+, Ni2+ and Zn2+, respectively, while for Cd and Fe, the dominant species were CdCl+ and Fe(OH)2+, respectively.  相似文献   

14.
The usefulness of Mehlich 3 (M3) reagent was evaluated as a method to extract numerous elements from coalmine soils in As Pontes (Spain) showing a wide range of physicochemical properties. Critical levels (deficiency and/or toxicity) were established for plant available elements extracted by this reagent. The M3 method was compared to 1M NH4Cl, Olsen, acid oxalate, and DTPA methods as extractants for exchangeable Ca, Mg and K, available P, non-crystalline aluminium, and available heavy metals, respectively. The M3 method correlated significantly to NH4Cl for Ca, Mg and K (r=0·76, 0·84 and 0·87, respectively), to Olsen P (r=0·77) and to oxalate Al (r=0·77). Significant correlations were found between Fe, Cu, Zn and Cd extracted by M3 and DTPA; for Mn, Ni, Co and Pb different relationship between methods were obtained for acid and alkaline samples, so that critical levels were established for M3 metals as a function of soil pH. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

15.
Abstract

Five soil extractants, namely, 0.005 M diethylene triamine pentaacetic acid (DTPA) (pH 7.3), 0.005 M DTPA+1 M ammonium bicarbonate (pH 7.6), Mehlich 3, 0.01 M ethylene diamine tetraacetic acid (EDTA)+0.05 M ammonium carbonate (pH 8.6), and 1 M magnesium chloride (MgCl2) (pH 6.0), were evaluated to predict the response of wheat to zinc (Zn) application in Mollisols. These extractants could be arranged in the following decreasing order of their Zn extracting power: Mehlich 3>0.005 M DTPA+1 M ammonium bicarbonate>0.01 M EDTA+0.05 M ammonium carbonate>0.005 M DTPA>1 M MgCl2. The critical limits of Zn in soil, below which the yield response to late sown wheat (var. UP‐2338) to Zn application could be expected, were 0.57 mg 0.005 M DTPA (pH 7.3) extractable and 1.72 mg Mehlich 3–extractable Zn kg?1 soil. The critical limit of Zn in whole shoot at 60 days after emergence was found to be 26.1 mg Zn kg?1 plant tissue. The DTPA and Mehlich 3–extractable soil Zn also correlated significantly and positively with Zn concentration in whole shoot at 60 days after emergence and total Zn uptake by wheat at harvest.  相似文献   

16.
Abstract

The objective was to find an uncomplicated test giving the best correlation between calcium (Ca), magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn), and lead (Pb) extracted from humic forest soil and the total concentration of the element in some understorey forest plants using well‐known extractants. The elements were selected because Ca, Mg, Mn, Cu, and Zn are essential nutrients to plants and Zn and Pb are potentially harmful heavy metals received over the years in the southern parts of Norway by long‐range atmospheric transport. Extraction of organic podzolic surface soil (Oe and Oa horizon) from 17 different pine forests in central and southern Norway was carried out with four different reagents to evaluate uptake of Ca, Mg, Mn, Cu, Zn, and Pb in the understorey plants Deschampsia flexuosa, Vaccinium myrtillus (leaves and stems), and Vaccinium vitis‐idaea (leaves and stems). The NH4OAc, NH4NO3, HCl, and EDTA solutions used to extract the soil in addition to concentrated HNO3, demonstrated variability in capacity to extract the different elements from the soil. The extractants yielded significant relations between concentrations of Ca, Mn, and Pb in the Oe or Oa horizon and some of the plants or plant compartments, even though distinct correlation was more dependent on species and plant part than the actual extractant used. In the case of Zn, Cu, and Mg only a few sporadic correlations were observed between the different plant/plant compartments and the element concentrations in the soil extracts. Altogether none of the extractants was shown to be superior to the others in providing the best correlation with the elements concentrations in selected plant/plant compartments. In the case of Ca, Mn, and Pb all the extractants including concentrated HNO3 provided significant correlations with at least some of the selected plant/plant compartments.  相似文献   

17.
Abstract

The purposes for this research were: to examine the long‐term residual effects of farmland applications of municipal sludges from four treatment technologies on the total and extractable Zn, Cu, Mn, Fe, Pb, Ni and Cd concentrations in Coastal Plain soils; to investigate the effects of sludge sources and rates on the effectiveness of soil extractants to remove the various metals; and to determine correlation coefficients for soil extractable versus plant accumulation in tobacco. The extractants evaluated were Mehlich 1 and 3, and DTPA‐pH 7.3. Composite Ap horizon soil samples and tobacco leaf samples were obtained in 1984 from research plots at two sites in Maryland that were established in 1972 and 1976, respectively, using sludge materials from three wastewater treatment facilities in the Washington, D.C. metropolitan region. Similar application rates were used at both sites.

A wide range in soil pH values was found among treatments at each site. Significant (p ≤ 0.05) increases were observed in total Zn, Cu, Fe, Pb, Ni, and Cd for all sludge sources with increased rates; however, values for total soil Mn exhibited high variability in all cases. The rankings among the extractants varied for some elements depending on the sludge sources. For Zn, the rankings were Mehlich 1 > Mechlich 3 > DTPA‐pH 7.3 across all sources and rates. For Cu, Mehlich 3 > Mehlich 1 > DTPA‐pH 7.3 was found for soils amended with Blue Plains digested (BPD) and Piscataway limeddigested (PLD) sludges but Mehlich 1 ≥ DTPA pH 7.3 > Mehlich 3 for Blue Plains limed compost (BPLC) and Annapolis Fe and heat treated (AFH) sludges. Concerning extractable Mn, Mehlich Mehlich 1 > Mechlich 3 > DTPH pH 7.3 was the order for BPLC and AFH sludges but Mehlich 3 > Mehlich 1 > DTPA‐pH 7.3 was observed for BPD and PLD sludges. The rankings among extractants for Fe (Mehlich 3 > Mehlich 1 > DTPA‐pH7.3), Ni (Mehlich 3 ≥ Mehlich 1 > DTPA‐pH 7.3), Pb (Mehlich 3 > DTPA‐pH 7.3 > Mehlich 1) and Cd (Mehlich 1 > Mehlich 3 > DPTA‐pH7.3) were somewhat similar across all sludge sources. Significant correlation coefficients were obtained for all three extractants for soil extractable vs. plant Zn, Cu, Ni, and Cd at both sites; however, Mehlich 3 was not significant for Mn. Also, neither of the extractants produced significant coefficients for Fe and Pb.  相似文献   

18.
Abstract

Vertisols of India are developed over isohyets of 600 to 1500 mm, and their chemical cycles are set by drainage, landforms, and particle size, which results in variable pedogenic development within the otherwise homogeneous soils. The purpose of this study was to identify pedogenic processes in the distribution of total and DTPA‐extractable zinc (Zn), copper (Cu), manganese (Mn), and iron (Fe). The soils are developed over basaltic parent material of Cretaceous age. Soil samples were drawn from genetic horizons of the 13 benchmark profiles and analyzed by using HF–HClO4 acid for total and DTPA extraction. Correlation coefficients were calculated taking all samples together. The total concentration varied from 24 to 102 mg kg?1 for Zn, 21 to 148 mg kg?1 for Cu, 387 to 1396 mg kg?1 for Mn, and 2.36 to 9.50% for Fe. Their variability was proisotropic and haplodized, and their concentrations increased with advancing isohyets. Within the isohyets, hindrance in drainage caused retention of Zn and Cu but loss of Fe. The piedmont soils had more Fe than alluvium soils. The spatial distribution of total contents of Zn, Cu, and Fe was influenced by the pedogenic processes associated with Haplusterts but not with provenance materials. Surface concentrations of the elements by biotic lifting and/or harvest removal were negated by the pedoturbation that further contributed to the irregular distribution of the elements in the profiles. Total Zn and total Cu had positive coefficients of correlations with coarse clay, whereas total Mn and total Fe were positively correlated with fine clay. The DTPA‐extractable forms were functions of isohyets and drainage and showed association with organic carbon content and coarse clay.  相似文献   

19.
The assessment of heavy metals in spinach (Spinacia oleracea) grown in sewage sludge–amended soil was investigated. The results revealed that sewage sludge significantly (P < 0.01) increased the nutrients and heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn) in the soil. The contents of metals were found to be below the maximum levels permitted for soils in India. The most agronomic performance and biochemical components of S. oleracea were found at 50% concentrations of sewage sludge in both seasons. The contents of Cd, Cr, Cu, Mn, and Zn in S. oleracea were increased from 5% to 100% concentrations of sewage sludge in both seasons. The order of contamination factor (Cf) of different heavy metals was Mn > Cd > Cr > Zn > Cu for soil and Cr > Cd > Mn > Zn > Cu for S. oleracea plants after application of sewage sludge. Therefore, use of sewage sludge increased concentrations of heavy metals in soil and S. oleracea.  相似文献   

20.
In this study, we selected three soil pedons on the shoulder, backslope, and footslope along a serpentine toposequence to measure cobalt (Co) extractability using six single‐extraction procedures. These extraction procedures are distilled water, 0.11 M acetic acid in the first step of the BCR sequential extraction (BCR1), 1 M ammonium acetate (NH4OAc; pH 7.0), 0.01 M calcium chloride (CaCl2), diethylenetriamine pentaacetic acid (DTPA), and 0.1 M hydrochloric acid (HCl). Although the Co concentrations in the water extracts of the study soils ranged from 0.15 to 0.93 mg kg?1, those with HCl extraction can be up to 22.1 mg kg?1. The extractable Co concentrations in the study soils demonstrate that the extraction capacity is in the order HCl > DTPA > CaCl2 ? NH4OAc > BCR1 > H2O. The percentages of extractable Co after applying the six single‐extraction procedures reveal that Co mobility is greatest in the soils on the backslope, moderate on the footslope, and least mobile on the shoulder.  相似文献   

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