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PubMed2005

Adsorption-desorption characteristics of cadmium in variable charge soils.

Cadmium (Cd) has received considerable attention because of its association with various human health problems. The behavior of adsorption-desorption of Cd at contaminated levels in two variable charge soils were investigated. The red soil (RAR) developed on the Arenaceous rock (clayey, mixed siliceous thermic typic Dystrochrept) adsorbed more Cd2+ than the red soil (REQ) derived from the Quaternary red earths (clayey, kaolinitic thermic plinthite Aquult). The characteristics of Cd adsorption could be described by the Freundlich equation (r2 = 0.997 and 0.989, respectively, for the RAR and REQ) and the simple Langmuir adsorption equation (r2 = 0.985 and 0.977, respectively, for the RAR and REQ). The maximum adsorption values (Xm) that were obtained from the simple Langmuir model were 36.23 mmol Cd2+ kg(-1) soil and 31.15 mmol Cd2+ kg(-1) soil, respectively for the RAR and REQ. Adsorption of Cd2+ decreased soil pH by 1.28 unit for the RAR soil and 1.23 unit for the REQ soil at the highest loading. The distribution coefficient (kd) of Cd in the soil decreased exponentially with increasing Cd2+ loading. The adsorption of cadmium in the two variable charge soils was characterized by a rapid process that lasted approximately 15 min, followed by a slower but longer period. 85.5% and 79.4% of the added Cd were adsorbed within two hours by the RAR and REQ soil, respectively. More Cd2+ was adsorbed at 10 degrees C than at 25 degrees C or 40 degrees C. After five successive desorptions with 0.01 mol L(-1) NaNO3 solution, 53.3% of the total adsorbed Cd2+ in the RAR soil was desorbed and the corresponding value of the REQ soil was 46.5%, indicating that the RAR soil had a lower affinity for Cd2+ than the REQ soil at the same Cd2+ loading.

Adsorption↗
PubMed2002

[Eco-toxicological effects of heavy metals on the inhibition of seed germination and root elongation of Chinese cabbages in soils].

The Eco-toxicity effects of individual Cu, Zn, Pb and Cd on the inhibition of seed germination and root elongation of Chinese cabbages (Brassica pekimensis) were tested in four types of soils (red loam soils, meadow brown soils, chestnut soils and dark brown soils) and water solution. The combined effects of heavy metals pollution were determined with meadow brown soils. Results indicated that with same concentration, the inhibition rates of heavy metals on root elongation of Chinese cabbages are stronger than that on the seed germination. The inhibition effects of heavy metals on the root elongation of Chinese cabbages in soils are much lower than that in water, indicating that soils play an important role of buffering on heavy metals pollution. Inhibition rates of heavy metals on the root elongation (IRHMRE) of Chinese cabbages are significantly negative related with the contents of organic matter (OR) and Kjedahl-nitrogen (K-N) in soils, however, there is no significant related between IRHMRE and soil pH, so does the content of T-K. In the concentrations that result in the irritated effect in the single form of Cu, Zn, Pb and Cd pollution, synergic effects are produced significantly when four heavy metals are combined. As the results, the threshold values that result in the inhibition effects on root elongation in Chinese cabbages decrease markedly.

Brassica↗
PubMed2002

[Eco-toxicology of heavy metals on the inhibition of seed germination and root elongation of wheat in soils].

The eco-toxicity of Cu, Zn, Pb, and Cd in the single form was tested with four types of soils(red loam soils, meadow brown soils, chestnut soils, and dark brown soils) and their combined effect was determined with meadow brown soils. The results showed that with the same content of heavy metals, the root elongation was strongly inhabited than the seed germination, and it indicated that root was more sensitive to heavy metals pollution. The inhibition rate of heavy metals pollution on the root elongation (IRHMRE) of wheat was significantly related with the contents of organic matter (OR) and Kjedahl-nitrogen (K-N) in soils (R2OR = 0.91, R2K-N = 0.92). However, IRHMRE was not significantly related with soil pH as did with OR and K-N, so does the content of CEC (R2pH = 0.62, R2CEC = 0.60). Whether under the low concentration of Cu, Zn, Pb, and Cd resulted in an irritated effect in root elongation, or under high concentration resulted in an inhibition effect in the single form, an synergistic effect occurred in the combined form.

Cadmium↗
PubMed2005

Effects of phosphate on the adsorption of glyphosate on three different types of Chinese soils.

Glyphosate (GPS) is a non-selective, post-mergence herbicide that is widely used throughout the world. Due to the similar molecular structures of glyphosate and phosphate, adsorption of glyphosate on soil is easily affected by coexisting phosphate, especially when phosphate is applied at a significant rate in farmland. This paper studied the effects of phosphate on the adsorption of glyphosate on three different types of Chinese soils including two variable charge soils and one permanent charge soil. The results indicated that Freundlich equations used to simulate glyphosate adsorption isotherms gave high correlation coefficients (0.990-0.998) with K values of 2751, 2451 and 166 for the zhuanhong soil(ZH soil, Laterite), red soil(RS, Udic Ferrisol) and Wushan paddy soil (WS soil, Anthrosol), respectively. The more the soil iron and aluminum oxides and clay contained, the more glyphosate adsorbed. The presence of phosphate significantly decreased the adsorption of glyphosate to the soils by competing with glyphosate for adsorption sites of soils. Meanwhile, the effects of phosphate on adsorption of glyphosate on the two variable charge soils were more significant than that on the permanent charge soil. When phosphate and glyphosate were added in the soils in different orders, the adsorption quantities of glyphosate on the soils were different, which followed GPS-soil > GPS-P-soil = GPS-soil-P > P-soil-GPS, meaning a complex interaction occurred among glyphosate, phosphate and the soils.

Adsorption↗
PubMed1977

Dehydrogenase activity and microbial population in a red sandy soil amended and unamended with incubation.

Incubation of single bulk sample of freshly collected red sandy soil in trays showed immediate response to added nutrients both in dehydrogenase activity and bacterial and fungal populations. The prevailing acidic pH might have been responsible for the observed response of fungi as well. Actinomycetes population did not fluctuate. It was therefore suggested that TTC dehydrogenase technique for measuring the biological activity could be applicable to coarse-textured and more open soils. There were indications that fungi contributed to the soil dehydrogenase activity as well.

Actinomycetales↗
PubMed2002

Effects of red-yellow soil acidification on seed germination of Chinese pine.

Acid treatments significantly change the physical and chemical properties of red-yellow soil by lowering its pH value and leaching out aluminum(Al) ions that are harmful to the growth of plants. The structure of soil will be damaged, resulting in higher viscosity, higher water retention rate and lower air permeability of the soil. The germination rate of Chinese pine(Pinus tobulacformic Carr.) seeds sowed in soil treated with sulphuric acid(H2SO4) decreased compared to that for untreated soil. The direct cause was the large amount of Al ions leached out because of low pH values(> or = 3.5). The added acid decreased the soil aggregation and increased the number of micro-aggregates(under 250 microns in diameter). Such changes increased the soil's viscosity, which tied the pine needles to the soil after the seeds had germinated and prevented the seedlings from fully developing.

Germination↗
PubMed2000

Adsorption characteristics of 47 elements on a calcareous soil, a red earth and an alumina: a multitracer study.

The distribution coefficients, Kd of 47 elements from Na to Bi on a calcareous soil, a red earth and an alumina were, respectively, determined using a multitracer technique. The multitracer solution was prepared by irradiation of UO2(NO3)2 with 40Ar ion beam. It was found that there is a common general trend of variation in Kd for both soils and the alumina, i.e. all the shapes of plots of log Kd versus electron binding energy (Iz) are an 'inverted V', hence the important role of chemical interaction in the adsorption of trace inorganic cations, anions and neutral complexes on the soils and the oxides was demonstrated. For the alkali and alkaline earth elements, the common sequences of Kd values on the three adsorbents were Na+ < K+ < Rb+ < Cs+ (except for Rb+ on the alumina) and Mg2+ < Sr2+ < Ba2+ and accord with the sequences of effective ionic radii or single ion hydration enthalpies.

Adsorption↗
PubMed2003

[Reserves and spatial distribution characteristics of soil organic carbon in Guangdong Province].

Soil organic carbon is the main part of terrestrial carbon reservoir and important part of soil fertility. The spatial distribution and reserves of soil organic carbon are very important for studying soil carbon cycle. According to the data from the second soil survey, soil organic carbon reserves was estimated and its spatial distribution was analysed by using GIS technique. The results showed that the total amount of soil organic carbon is about 17.52 x 10(8) t. The carbon density of laterite, lateritic red soil and red soil in Guangdong Province is 8.83, 10.31, 9.15 kg.m-2, respectively; lower than the mean carbon density of China. The carbon density of yellow soil and rice soil is 12.08, 12.17 kg.m-2, respectively; higher than the mean carbon density of China. Soil carbon density is about 10.44 kg.m-2 in Guangdong. The spatial distribution characteristic of soil organic carbon density in Guangdong is that the carbon density in south Guangdong Province is higher than that in north Guangdong Province, in that soil organic carbon density in north and middle Guangdong Province is 5-10 kg.m-2 and in east Guangdong Province is 10-15 kg.m-2. Soil organic carbon density mostly vary among 5-15 kg.m-2.

Carbon↗
PubMed2002

Phytotoxicity of dredged sediment from urban canal as land application.

Phytotoxicity of dredged sediment from Hangzhou section of the Grand Canal as land application was evaluated by pakchoi (Brassica chinensis L.) germination tests and pot experiments. Germination rates of pakchoi in the dredged sediment and in sediment-applied soils were both significantly higher than that in the soil controls, while the germination rate between the sediment-applied soils was no significant difference. In pot experiments, plant height and biomass were increased by the dredged sediment application rate in the rate of lower than 540 t ha(-1), but decreased when the application rate was over this rate. Concentrations of Zn and Cu in pakchoi were linearly increased with the increasing of the application rate of the dredged sediment. Both plant height and biomass of pakchoi in sediment-treated red soil were higher than that in sediment-treated paddy soil, regardless the application rate. The results suggest that plant biomass of pakchoi may be used as an indicator of the phytotoxicity of the dredged sediment. It also showed that red soil is more suitable to accept the dredged sediment than paddy soil, and 270 t ha(-1) is a safe application rate both in red soil and paddy soil.

Biomass↗
PubMed2005

Mobility and speciation of Cd, Cu, and Zn in two acidic soils affected by simulated acid rain.

Through a batch experiment, the mobility and speciation of heavy metals (Cd, Cu, Zn) in two acidic forest soils from Hunan Province were studied. The results showed that the release and potential active speciation of Cd, Cu, and Zn in the tested contaminated red soil (CRS) and yellow red soil (CYRS) increased significantly with pH decreasing and ion concentrations increasing of simulated acid rain, and these effects were mainly decided by the pH value of simulated acid rain. Cd had the highest potential risk on the environment compared with Cu and Zn. Cd existed mainly in exchangeable form in residual CRS and CYRS, Cu in organically bound and Mn-oxide occluded forms, and Zn in mineral forms due to the high background values.

Acid Rain↗
PubMedDate not supplied

[Weight distribution and optical characteristics of soil humic acids fractionated by gel chromatography and electrophoresis].

Combination of gel chromatography on Sephadex and polyacrylamide gel electrophoresis was used to obtain molecular weight- and electrophoretic mobility-uniform fractions of humic acids from soil of different types (chernozem, sod-podzol, grey forest, and red soils). Extinction and color (E4/E6) coefficients, as well as weight distribution (%) were studied for all humic acids and their fractions. The fractions differed by the weight distribution (%). Sod-podzol and red soils had twice the amount of high-molecular and half the amount of low molecular HA fractions as compared to chernozem and grey forest soil.

Chemical Fractionation↗
PubMed2003

[Factors dominating the sorption of bentazon in soils].

Adsorption isotherms of bentazon in six selected soils were measured by using batch sorption method. Meanwhile the mean partial free energy change of chemical in sorption process was also calculated. The results showed the adsorption isotherms of herbicide in five soils all were linear, distribution coefficients (Kd) ranged from 0.14 mL.g-1 to 0.31 mL.g-1, and the extent of soils adsorption the herbicide followed: Deqing paddy soil > Ji'an paddy soil(pH4.79) > Yuhang paddy soil > Lin'an red soil > Ji'an paddy soil(pH7.36) > Deqing loess. Investigation of Kd vs. properties of soils indicated that both of the pH and content of soil organic matters were dominating factors that affected the adsorption of bentazon in soils, and adsorption of bentazon in soils equated the partitioning of neutral and anion form bentazon into soil organic, which was independent of the natural of soil organic matters.

Adsorption↗
PubMed2003

[The influence of simulated acid rain on acidity and K+ leaching regulation of different soil layers].

The influence of simulated acid rain on acidity and K+ release of different soil layers of red soil from Jiangxi was investigated in the lab when surface soil was mixed with KCl. The results indicated that pH of leaching solution first decreased, then increased in the different soil layers, but pH at the beginning moment of leaching existed prominent differences and pH of leachate of pH 2.5 acid rain in A and AB layers again decreased during subsequent stage. There was a peak value of EC of leachate appearing at the beginning stage, it showed that nutrient ions in soil rapidly moved downwards into lower depth of profile. K+ concentration of effluent solution was related to acidity of acid rain and the pH2.5 value of acid rain accelerated K+ transportation downwards along profile. K+ release of A soil layer was divided into two moments which one was the rapid rate of K+ release process at the moment of beginning and then into the middle rate of release process. As to pH 4.5 value of acid rain, it also existed rapid and slow rate processes.

Acid Rain↗
PubMed2006

Phototransformation of alphacypermethrin as thin film on glass and soil surface.

Photodegradation of alphacypermethrin ((RS)-alpha cyano-3-phenoxy benzyl (1RS) cis-3-(2,2,dichlorovinyl)-2,2-dimethyl cyclopropane carboxylate) was studied as a thin film on glass surface and on black and red soil surfaces. A number of photoproducts from glass surfaces have been isolated, characterized and identified by gas chromatography-mass spectroscopy (GC-MS). However, only two of them viz. 3-phenoxy benzyl alcohol and [2,2-dichlorovinyl-3(2,2,dimethyl) cyclopropane carboxylate] could be identified from both the soil. Rate of photodegradation on glass and soil surface under UV and sunlight followed first order kinetics with significant correlation coefficients. The rate of photodegradation was greater on black than on red soil.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Growth, biomass, carbon storage and nutrient distribution in Gmelina arborea Roxb. stands on red lateritic soils in central India.

Growth, biomass, carbon storage and nutrient (N, P and K) variations in 1 to 6-year-old chronosequence plantations of Gmelina arborea were studied in three degraded red lateritic sites in central India. Growth parameters (dbh, total height and number of branches) varied significantly due to difference in age and site quality, but tree density showed non-significant variation. Stand biomass ranged from 3.94 (1-year-old) to 53.67 Mgha(-1) (6-year-old) and stand carbon in 6-year-old plantations ranged from 24.12 to 31.12 Mgha(-1) at different sites. Among the tree components, the stem wood accounted for maximum C (56.25% at site 1) followed by branches (19.8% at site 3), roots (18.51% at site 2) and foliage (7.01% at site 3). Mean annual C accretion at 6 years age of plantation was highest in site 3 and it was 0.35, 2.66, 0.965 and 0.87 Mgha(-1) for leaf, stem, branches and roots, respectively. Quantity of nutrients increased with age. Total nitrogen accumulation in 6-year-old stands at the three sites ranged from 212.9 to 279.5 kgha(-1) with a mean annual storage of 238.43 kgha(-1) and total K ranged from 170.8 to 220.5 kgha(-1) with a mean annual storage of 189.93 kgha(-1). Phosphorous accumulation was lowest with a mean storage of 16.75 kgha(-1). The organic carbon and nutrients in the soils improved significantly after 6 years of G. arborea planting. Soil organic carbon increased from 8.46 to 14.02 Mgha(-1) within 6 years. At soil depths 0-20 cm, 21-40 cm and 41-60 cm, available N enhanced by 14.85%, 11.98% and 11.25%, K by 10%, 9.13% and 10.63%, whereas phosphorous declined by 26%, 23% and 20%, respectively. At 6 years, G. arborea stands sequestered 31.37 Mgha(-1) carbon. The nutrient management strategies in relation to carbon accretion in G. arborea stands on degraded lateritic sites are discussed.

Biomass↗
PubMed2002

[Cadmium adsorption in soil influenced by dissolved organic matter derived from rice straw and sediment].

Dissolved organic matter (DOM) is an active component in territorial ecosystems. Effects of two types of DOMs extracted from sediment(DOMsed) and rice straw(DOMrs) on isotherm adsorption of Cd in latosol red soil (acidic soil), paddy soil and drab soil(alkaline soil) were studied using batch equilibrium studies. The maximum adsorption of Cd in all the 3 soils used was reduced by the additions of both of DOMsed and DOMrs. The range of the maximum adsorption of Cd decreased from 17.3% to 93.9% from all the 3 soils when DOMs were added. It was found that the decreased in the maximum adsorption of Cd was in order of latosol red soil > paddy soil > drab soil when the same DOM(DOMsed or DOMrs) was added. Effects of DOMsed or DOMrs on Cd adsorption were positively related with the soil pH. The maximum adsorption of Cd in the soils was dependent on the characteristics of soil solid when no DOM was added, and decided by the DOMs in soil solution when DOM was added. The results imply that the proposed technology using organic manure to stabilize Cd in soils is not suitable for remediation of contaminated soil.

Absorption↗
PubMed2004

[Kinetic characteristics of Cd2+ desorption in minerals and soils under simulated acid rain].

The kinetic characteristics of Cd2+ desorption in minerals and soils under simulated acid rain were studied by using the flow-stirred method. It showed that Cd2+ desorption could be described by first-order kinetics. Percents of desorption amounts of Cd2+ calculated were 70%-100% in red soil and goethite, and 25%-50% in latosols and kaolinite. Parabolic diffusion could describe Cd2+ desorption kinetics in latosols and not suitable for red soil and goethite and kaolinite. Cd2+ desorption, regarded as a heterogeneous diffusion in minerals and soils, could be fitted by Elovich equation more than Parabolic diffusion and two-constant equation. Cd2+ desorption could be divided into fast reaction and slow reaction. Except for latosols, fast reaction would be over during 60 min and be close to quasi-equilibrium. Adsorption forms of Cd2+ in soil surface could be exchangeable and specific. Fast reaction was relative to easily desorbed Cd2+. The affinity of edge hydroxyl to Cd2+ would lead to the difference of Cd2+ desorption rate and amounts. Increase of pH value in effluent indicated H+ consumption in the processes of Cd2+ desorption.

Acid Rain↗
PubMed2004

[Lead absorption by weeds from lead-polluted soil].

A pot experiment with red soil was installed in 2002 and 2003 to study the impact of lead pollution on weed growth, its lead and nutrients uptake, and AMF colonization. The results showed that lead pollution had no significant influence on weed growth, and the absorbed lead was mainly accumulated in root system. The impact of lead pollution on nutrients uptake by weeds was depended on weed species, their growth stages, and kinds of nutrients. No significant difference was found between lead treatment and control in nutrient contents except potassium in Digitaria adscendens at its early growth stages, and lead had little influence on the absorption of nutrients by Kummerowia striata, Ixeris chinensis, Digitaria adscendens and Echinochloa crusgalli var. mitis. The phosphorus content in Ixeris chinensis and Digitaria adscendens at their ripen stage sampled from lead-polluted soil was significantly higher than that from control, while the nitrogen content in matured Echinochloa crusgalli var. mitis sampled from polluted soil was significantly lower than that from the control. There existed great difference of mycorrhizal colonization among various weed species. The infection rate of Kummerowia striata and Digitaria adscendens showed a slight difference between lead treatment and control both at vegetative and ripen stage. Lead pollution hindered the colonization of Ixeris chinensis. In lead-polluted soil, the AMF infection rate of Ixeris chinensis was 45.52% at vegetative stage and 74.64% at ripen stage, while in the control, it was 69.44% at vegetative stage and 82.21% at ripen stage. Echinochloa crusgalli var. mitis, an annual weed, showed an opposite response of AMF colonization to lead pollution. The colonization rate of AMF in Echinochloa crusgalii var. mitis root was higher under lead pollution condition, being 82.45% at vegetative stage and 91.36% at ripen stage, while in the control, it was 59.19% and 78.28%, respectively.

Absorption↗