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1.
根迹土壤根诱导的化学变化对植物吸收重金属的影响   总被引：4，自引：0，他引：4  
K. R. KIM  G. OWENS  R. NAIDU 《土壤圈》2010,20(4):494-504
It is increasingly recognized that metal bioavailability is a better indicator of the potential for phytoremediation than the total metal concentration in soils; therefore, an understanding of the inffuence of phytoremediation plants on metal dynamics at the soil-root interface is increasingly vital for the successful implementation of this remediation technique. In this study, we investigated the heavy metal and soil solution chemical changes at field moisture, after growth of either Indian mustard (Brassica juncea) or sunffower (Helianthus annuus L.), in long-term contaminated soils and the subsequent metal uptake by the selected plants. In addition, the fractions of free metal ions in soil solution were determined using the Donnan membrane technique. After plant growth soil solution pH increased by 0.2-1.4 units and dissolved organic carbon (DOC) increased by 1-99 mg L-1 in all soils examined. Soluble Cd and Zn decreased after Indian mustard growth in all soils examined, and this was attributed to increases in soil solution pH (by 0.9 units) after plant growth. Concentrations of soluble Cu and Pb decreased in acidic soils but increased in alkaline soils. This discrepancy was likely due to a competitive effect between plant-induced pH and DOC changes on the magnitude of metal solubility. The fractions of free Cd and Zn ranged from 7.2% to 32% and 6.4% to 73%, respectively, and they generally decreased as pH and DOC increased after plant growth. Metal uptake by plants was dependant on the soil solution metal concentration, which was governed by changes in pH and DOC induced by plant exudates, rather than on the total metal concentrations. Although plant uptake also varied with metal and soil types, overall soluble metal concentrations in the rhizosphere were mainly inffuenced by root-induced changes in pH and DOC which subsequently affected the metal uptake by plants.  相似文献   

2.
石灰与磷肥可以降低华南5种常见蔬菜对镉的吸收量   总被引：7，自引：0，他引：7  
A pot experiment was conducted in artificially Cd-contaminated (5 mg Cd kg-1) soils to investigate the feasibility of using lime (3 g kg-1) or phosphate (80 mg P kg-1) to mitigate uptake of Cd by vegetables.Five common vegetables in South China,including lettuce (Lactuca sativa L.var.ramosa Hort.),Chinese cabbage [Brassica rapa L.subsp.Chinensis (L.) var.parachinensis (L.H.Bailey) Hanect],Chinese broccoli (Brassica oleracea L.var.albiflora Kuntze),white amaranth (Amaranthus tricolor L.) and purslane (Amaranthus viridis L.),were grown in the soils and harvested after 60 d.The results showed that liming significantly reduced Cd uptake by most vegetables by 40%-50% (or a maximum of 70%),mainly due to immobilization of soil Cd.Increased availability of Ca in the soil might also contribute to the Cd uptake reduction as a result of absorption competition between Ca and Cd.Liming caused biomass reduction in white amaranth and purslane,but did not influence growth of the other vegetables.Phosphate decreased Cd uptake by vegetables by 12%-23%.Compared with lime,phosphate decreased,to a smaller extent,the bioavailability of Cd in most cases.Phosphate markedly promoted growth of vegetables.Changes in soil chemistry by adding lime or phosphate did not markedly influence nutrient uptake of vegetables except that lime increased Ca content and phosphate increased P content in shoots of the vegetables.The results suggested that a proper application of lime could be effective in reducing Cd uptake of vegetables,and phosphate could promote growth of the vegetables as well as alleviate the toxicity of Cd.  相似文献   

3.
A study was carried out on contribution of iron phosphate to phosphorus nutrition of rice plant under waterlogged and moist conditions,respectively,by use of synthetic Fe^32 PO4.nH2O,tagging directly the iron phophate in calcareous paddy soils.Results showed that under waterlogged condition,similar to iron phosphate in acidic paddy soils.that in clacareous paddy soils was an important source of phosphorus to rice plant ,and the amount of phosphorus originated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.  相似文献   

4.
基于小白菜Cd吸收推算土壤Cd安全阈值   总被引：3，自引：0，他引：3  
Cadmium(Cd), a common toxic heavy metal in soil, has relatively high bioavailability, which seriously threatens agricultural products. In this study, 8 different soils with contrasting soil properties were collected from different regions in China to investigate the Cd transfer coefficient from soil to Chinese cabbage(Brassica chinensis L.) and the threshold levels of Cd in soils for production of Chinese cabbage according to the food safety standard for Cd. Exogenous Cd(0–4 mg kg~(-1)) was added to the soils and equilibrated for 2 weeks before Chinese cabbage was grown under greenhouse conditions. The influence of soil properties on the relationship between soil and cabbage Cd concentrations was investigated. The results showed that Cd concentration in the edible part of Chinese cabbage increased linearly with soil Cd concentration in 5 soils, but showed a curvilinear pattern with a plateau at the highest dose of exogenous Cd in the other 3 soils. The Cd transfer coefficient from soil to plant varied significantly among the different soils and decreased with increasing soil p H from 4.7 to 7.5. However, further increase in soil pH to 8.0 resulted in a significant decrease in the Cd transfer coefficient. According to the measured Cd transfer coefficient and by reference to the National Food Safety Standards of China, the safety threshold of Cd concentration in soil was predicted to be between 0.12 and 1.7 mg kg~(-1) for the tested soils. The predicted threshold values were higher than the current soil quality standard for Cd in 5 soils, but lower than the standard in the other 3 soils. Regression analysis showed a significant positive relationship between the predicted soil Cd safety threshold value and soil p H in combination with soil organic matter or clay content.  相似文献   

5.
水培法磷矿石对小麦生长的影响   总被引：1，自引：0，他引：1  
Screening cultivars to grow under conditions of low phosphorus (P) availability and utilize P efficiently from compounds of low solubility in soils may be beneficial to overcome poor plant growth in P-deficient soils.The growth behavior and P utilization efficiency of seven wheat cultivars grown in hydroponics were studied,using rock phosphate as P source.The wheat cultivars grown for 30 days were significantly different in biomass accumulation,P uptake and P utilization efficiency.The dry matter production of all the cultivars was significantly correlated with P uptake,which in turn correlated to the drop in the root medium pH.The ranking of wheat cultivars on the basis of dry matter yield,P uptake and P utilization efficiency was Zamindar 80 ＞ Yccora ＞ C 271 ＞ WL 711 ＞ Barani 83 ＞ PARI 73 ＞ Rohtas.The cultivar Zamindar 80 appeared to possess the best growth potential in P-deficient soils.  相似文献   

6.
Phosphorus (P) is an essential nutrient required for plant development.Continuous population growth and rising global demand for food are expected to increase the demand for phosphate fertilizers.However,high-quality phosphate rock reserves are progressively becoming scarce.Part of the increased pressure on P resources could be alleviated by recycling P present in biosolids.Therefore,it is crucial to understand the dynamics of P in biosolid-amended soils,the effects of residual biosolid-borne P in soils,the way in which microorganisms may control P dynamics in biosolid-amended soils and the environmental implications of the use of biosolids as a source of P.Further research is needed to maximize biosolid-borne P uptake by crops and minimize its loss from biosolid-amended soils.The analysis of the microbiological control of P dynamics in biosolid-amended soils indicates interactions of biosolid P with other nutrients such as carbon (C) and nitrogen (N),suggesting that harmonization of the current regulation on the use of biosolids in agriculture,mainly based on total N and pollutant contents,is needed to better recycle P in agriculture.  相似文献   

7.
石灰处理对红壤中镉形态及其毒性的影响   总被引：1，自引：0，他引：1  
The effect of liming 4 red soils developed from Quaternary red clay and red sandstone on the cadmium forms and its toxicity were investigated. Liming the acid red soils could greatly reduce Cd toxicity to plants because the soluble Cd and organic Cd in the soils decreased significantly while Cd bound to minerals/oxides and residual Cd increased markedly with increasing lime rates (pH).  相似文献   

8.
The experiments were conducted in the artificial climate laboratory using 32P labelled soil and soil-root plane system to investigate phosphate distribution and its movement in the soil-root interface zone and their relations with phosphate uptake by plant as well as transpiration rate (atmosphere humidity).It was found that although the phosphate in the soil-root interface zone was of depletive distribution as a function C/Co=ax^b(C/Co is the relative content of fertilizer phosphate in a distance from the root surface x,a and b are the regression constants),and a relative accumulation zone of phosphate within 0.5 mm near the root surface was often boserved especially in the heavier texture soils because of root phosphate secretion.The depletion intensity of phosphate in the soil-root interface zone was in agreement with the phophate uptake by plants under two humidities very well.However,the effects of air humidity on characteristics of the phosphate distribution near wheat or maize root surface were different.Wheat grew better under lower atmosphere humidity while maize,under higher humidity,which caused a more intensive uptake and thus a stronger depletion of phosphate in the rhizosphere,Moreover,the depletion intensity was greater by the bottom or the middle part of wheat roots and by the top or the middle part of maize roots.The depletive distribution of phosphate in the rhizosphere soil and the relative contribution of phosphate diffusion to plant,which was more than 98% in the cultural experiments,indicated that diffusion was a major process for phosphorus supply to plants.  相似文献   

9.
A pot experiment was carried out to study the effects of two amendments, lime and calcium magnesium phosphate, on the growth and Cd,Pd,Zn,Cu,Mn,Fe,N,P and K uptake of pakchoi (Brassica chinensis) in a Cd,Pb and Zn polluted acid soil in the southern part of China. The growth of pakchoi was apparently improved by lime and calcium magnesium phosphate application, the uptake of Cd,Pb,Cu and Zn by pakchoi was significantly depressed and the symptom caused by heavy metals pollution was eliminated. Meanwhile, the absorption of N,K and Mn was also inhibited by these amendments. Soil pH was the main factor controlling the uptake of the heavy metals by pakchoi. This suggests that lime and calcium magnesium phosphate could be used as effective amendments for eliminating the toxicity of heavy metals to the vegetable and inhibiting their absorption by the crop.  相似文献   

10.
Most previous researches have focused on biochar application in agricultural soils; however, limited information is available concerning the effects of biochar amendment on greenhouse substrate properties. A greenhouse experiment was conducted to investigate effects of wheat straw biochar(0–160 m L L-1) and super absorbent polymer(SAP, 0.8 g L-1) on physical and chemical properties of a substrate based on spent pig litter compost and the growth of water spinach(Ipomoea aquatica Forsk). Total porosity, water-holding capacity, p H and electrical conductivity(EC) of the substrate significantly increased with increasing biochar rates, especially in the substrate without SAP. The values of p H and EC were significantly lower in the substrate with SAP than those without SAP at the high biochar application rates(100–160 m L L-1). The germination rates of water spinach decreased with increasing biochar rates when biochar was added alone(76.9%–83.7%), whereas the rates increased to 83.6%–85.8% when biochar was added in combination with SAP. Growth parameters of water spinach and nutrient uptake by shoots and roots increased with increasing biochar rates and reached the maximum values at the biochar rate of 100 m L L-1. There were significant cubic relationships between the uptake of nutrients(N, P, and K) and biochar rates, both with and without SAP addition. In order to avoid negative effects on plant growth,the biochar application rate should be controlled at an optimal level(100 m L L-1). The SAP addition not only enhanced the positive effects of biochar application on the properties of the substrate, but also inhibited the excessive rise of p H and EC following biochar additions, which led to better plant growth and enhanced nutrient uptakes by water spinach.  相似文献   

11.
A pot experiment was conducted to compare the behaviour and bioavailability of Cd and Pb from two soils mixed with sewage sludge at three rates (0, 50 and 150 t ha?1) and maintained at two contrasting ambient temperatures (15°C and 25°C) over a period of one year following the treatments. Ryegrass (Lolium perenne) accumulated Cd and Pb in the sewage sludge treated soils, although accumulation was significantly lower in the soils treated at the high rate (150 t ha?1) compared to the low rate (50 t ha?1). Ryegrass grown in the warm environment (25°C) accumulated significantly higher levels of Cd and Pb than that grown in cooler conditions (15°C). Samples of the soils spiked with nitrate salts of Cd and Pb at equivalent rates of metal loading resulted in the ryegrass accumulating much higher levels of both the metals than on the sludge treated soils. Metal uptake by the ryegrass from the sludge treatments increased over successive harvests while that from metal salt treatments decreased. The observed trend of increasing plant metal uptake over time coincided with a trend of decreasing pH in the sludge treatments. However, the concentrations of Cd and Pb extracted by DTPA failed to predict the changes in plant metal uptake. The importance of sewage sludge as both a source and a sink of pollutant metals and the trend of increasing bioavailability over time shown by this experiment are discussed.  相似文献   

12.
The influence of soil redox potential on the uptake of nickel and cadmium from three soils was studied in a pot experiment with oat (Avena sativa L. cv. Pirol) and rye-grass (Lolium multiflorum L. cv. Lema). The soils used were a Luvisol (naturally low in Ni and Cd), a sewage-sludge amended Luvisol (anthropogenic enrichment of Ni and Cd) and a Cambisol (naturally high in Ni and Cd). Nickel and Cd supplied in sewage-sludge amendments were several times more available for plant uptake than those present naturally in the soil. Short term decreases in soil redox potential, as a result of soil flooding, had little effect on the availability of Ni and Cd from sludge amended soils, but resulted in a substantial increase in Ni and Cd availability in the soil naturally high in Ni and Cd. In general, increases in soil solution concentrations of Ni and Cd, due to sludge amendment or changes in soil redox potential, resulted in increased Ni and Cd concentrations in the aerial parts of plants. Nickel concentrations in the grain of oat increased with increasing Ni concentration in the soil solution, whereas grain Cd concentrations did not. In contrast, Cd concentrations in vegetative parts of both oat and rye-grass were strongly affected by soil type and sludge-amendment. In all treatments Ni concentrations in the grain were much higher than in the vegetative parts, whereas Cd concentrations were always higher in vegetative parts than in the grain. Tissue Ni concentrations correlated well with DTPA extractable soil Ni but only poorly with total soil Ni. Differences in the availability and uptake of Ni and Cd in response to soil type, environmental conditions and plant species suggest that the use of total soil-metal content to regulate the use of sewage sludge on agricultural land is inappropriate.  相似文献   

13.
不同氮磷钾肥对土壤pH和镉有效性的影响   总被引：32，自引：1，他引：31  
采用土壤培养方法研究了不同氮、磷、钾肥对土壤pH和镉有效性的影响。结果表明,在培养60 d时,所有氮肥处理均降低了土壤pH,增加了Cd的提取量;但高量尿素和氯化铵处理土壤pH降低最多,提取的Cd也最多;硫酸铵提取的Cd较对照增加最小。所有磷肥处理均引起土壤pH小幅降低,但对土壤Cd提取量的影响以普钙稍大。3种钾肥处理均降低了土壤pH,其中氯化钾在0 d时提取的Cd在所有钾肥处理中为最高,其提取能力15 d后逐渐消失,试验结束时所有钾肥处理对Cd提取量均低于对照。本研究进一步表明,在土壤Cd含量处于污染临界值附近或已受Cd污染的土壤上,应避免施用高量的酸性肥料如尿素、氯化铵、普钙,以及其他酸性物料。在常用磷、钾肥中,磷酸二铵和硫酸钾在Cd污染土壤上施用更为适合。  相似文献   

14.
镉污染土壤植物修复的EDTA调控机理   总被引：49，自引：0，他引：49       下载免费PDF全文
我们通过温室盆栽试验 ,在不同Cd处理的土壤中加入EDTA ,分析了印度芥菜根和地上部Cd的浓度 ,探讨EDTA进入土壤后对Cd吸收和运输的影响。结果表明 :加入EDTA ,水提取的Cd浓度增加了 40 0倍以上 ,NH4 NO3提取的Cd浓度增加了 40倍以上 ,在土壤Cd浓度较低时 ,EDTA对植物吸收Cd没有显著影响 ,当土壤添加Cd在 1 3 0mgkg- 1以上时 ,加入EDTA显著增加了地上部Cd的浓度。EDTA能增加印度芥菜地上部中Cd的浓度 ,不是由于土壤溶液中Cd浓度增加从而增加了印度芥菜根对Cd的吸收 ,可能是EDTA加入土壤后增加了这些元素在土壤溶液中的浓度 ,从而高浓度的Cd对植物根细胞产生毒害 ,增加了细胞膜的透性后 ,土壤溶液中的络合物得以进入根细胞并随蒸腾作用运输到地上部。  相似文献   

15.
Summary Inconsistent results were obtained from comparative studies on the impact of increasing Cd contamination in three soils on growth of spring-wheat plantlets and soil respiration. With identical soil Cd loads, plant growth was increasingly inhibited in the following sequence: Neutral sandy hortisol (pH 7.0) < phaeosem (pH 6.9) < acidic cambisol (pH 5.6), suggesting a strong dependence on pH. In contrast, oxidation of a glucose-glutamate mixture by these soils was increasingly inhibited in the sequence: Acidic cambisol < neutral sandy hortisol < phaeosem. Inhibition of plant growth was correlated with the extractability of Cd from soils by 0.1 M CaCl2. However, comparison of dose-response curves with dose-extractability and dose-uptake curves suggested the presence of a soil factor that modified plant uptake of available Cd. This factor, possibly the concentration of antagonistic cations, was apparently also active within the plants. The inconsistency in the responses of plant growth and of soil respiration with respect to the soil Cd load was ascribed to microbiological soil properties exceeding the importance of Cd availability. Relatively high in vitro sensitivity of prokaryotes and their biochemical interdependence together with relatively high diversities of streptomycetes and fungi were paralleled by a relatively strong inhibition of soil respiration.  相似文献   

16.
Heavy metal environmental pollution which occurs as a result of lime contaminated with cadmium (Cd) poses a potential health hazard. This investigation was undertaken to study uptake of Cd by strawberry plants grown in soil amended with three different sources and two different rates of industry waste lime containing 3.4, 14.3, and 60.0 mg Cd/kg, respectively. The effects of Cd applied to the soil were investigated, including its distribution in the soil and effect on Cd concentration in strawberry cv. Senga Sengana (Fragaria anassa) leaves and fruit in response to soil organic matter content and lime rates. Cadmium accumulated mainly in the plough layer, increasing from 0.170 mg Cd/kg (background level) to a maximum of 1.2 mg Cd/kg. Fruit had very high, hazardous Cd concentrations regardless of its content in the soil. This indicates that Cd was easily taken up by strawberry plants and accumulated in upper plant parts, including the fruit. Soil Cd content had no effect on concentration of this element in strawberry fruit. However, plant Cd uptake and fruit concentration was increased in acid soils even when soil Cd concentration was low.  相似文献   

17.
Soil-plant transfer models are needed to predict levels of cadmium (Cd) in vegetables when evaluating the food chain risks of Cd contamination in agricultural soils. In the present study, the transfer of Cd from a wide range of soils into tomato plants was investigated in order to identify the major factors and to develop predictive models. It was found that soil pH was the main factor controlling Cd uptake and lower pH was more favorable for Cd bioaccumulation. Furthermore, the hydrogen ion activity, other than pH, was correlated linearly with the ratio of plant Cd to soil Cd. Combining soil Cd, and the interaction between soil Cd and hydrogen ion activity greatly improved the model to predict the transfer of Cd from soil to plant. Compared with the previous log transformation model, the predicted model improved the regression coefficient from 0.799 to 0.973 and has important significance in practice.  相似文献   

18.
In a pot experiment, three N-fertilizers, differing in NO? 3 and NH+ 4; content, were compared in terms of their effects on the extractability of soil Cd in 1M ammonium acetate at pH 7 and on the uptake of native and added Cd by winter rape (Brassica napus L. var. oleifera Metzger). In another similar experiment the Cd-availability in soils receiving NPK-fertilizer applied in a concentrated, granulated form was compared to that in soils receiving a uniform application of dissolved NPK-fertilizer. Both loamy sand and clay soils were used. With the N-fertilizers levels of extractable soil Cd and plant Cd-contents were lowest in the nitrate of lime treatment, highest in the ammonium sulphate treatment and intermediate in the nitro-chalk treatment. The addition of 1 mg kg?1 DW Cd to the soil increased Cd-levels but did not change the response pattern. There was a strong association between the effects of the various fertilizers on Cd availability and their effects on soil pH: the stronger the acidifying effect the higher the Cd availability. When applied at a low dose, granular NPK was more effective than dissolved NPK at enhancing plant uptake of Cd from both soils, but this was not the case when applied at a higher dose to the sand. The two forms of NPK differed little in their effect on extractable soil Cd. Plant uptake of Cd was greater from soils receiving granular NPK with a high Cd-content than from those receiving granular NPK low in Cd. In both experiments extractable Cd was taken up to a greater extent from the sand than from the clay. An increase in fertilizer dose generally resulted in an increase in levels of soil-Cd and in Cd concentrations in the plants.  相似文献   

19.
董蓓  周嘉文  詹娟  程新峰  周通  王雨阳  周守标  吴龙华 《土壤》2022,54(6):1240-1246
酸性土壤上易产生铝（Al）毒害作用，缓解Al毒对于污染土壤上超积累植物的生长及重金属有效削减具有重要意义。本研究比较了不同措施对镉（Cd）超积累植物伴矿景天的Al胁迫缓解作用，结果发现：① 在水培条件下，锌添加可促进了Al胁迫下伴矿景天根表Cd2+吸收速率，而添加氯化钙或柠檬酸没有显著的缓解作用；② 在盆栽试验条件下，添加石灰处理显著提高了土壤pH，促进了伴矿景天生长和地上部对Cd的吸收，但添加生物质炭或柠檬酸没有显著缓解Al毒对伴矿景天生长和Cd吸收的抑制，添加柠檬酸反而加剧了土壤酸化，提高了土壤Al的活性；③在伴矿景天与荞麦间作条件下，其一定程度上降低了土壤的Al活性，在合适的种植密度下并未显著影响伴矿景天单株地上部Cd吸收量。综上，酸性土壤上耐Al作物与修复植物间作、结合添加改良剂调控Al毒，能够不显著降低土壤Cd的有效性和修复植物的Cd吸收，进而实现污染土壤的边生产边修复。  相似文献   

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