Speciation of cadmium in soil solutions of saline/sodic soils and relationship with cadmium concentrations in potato tubers (Solanum tuberosum L.)

Soil Research ◽  
1997 ◽  
Vol 35 (1) ◽  
pp. 183 ◽  
Author(s):  
M. J. McLaughlin ◽  
K. G. Tiller ◽  
M. K. Smart

Fifty commercial potato crops and associated soils were sampled. Soil solutions were extracted from rewetted soils by centrifugation, and solution composition was related to Cd concentrations in tubers. Soils were also extracted with 0·01 M Ca(NO3)2 and 0·01 M CaCl2 solutions, and Cd2+ activities in the extracts were calculated by difference using the stability constants for formation of CdCl2-nn species. The soils had saline solutions (>4 dS/m), and Cl- and SO2-4 in solution markedly affected the speciation of Cd in soil solution, with chloro-complexes, in particular, dominating. While low soil pH was associated with high (>25 nM) concentrations of Cd in soil solution, chloro-complexation also led to high concentrations of Cd in solution, even at neutral to alkaline soil pH values. Tuber Cd concentrations were not related to activities of Cd2+ in soil solution or to activities in dilute salt extracts of soil. Tuber Cd concentrations were related to the degree of chloro-complexation of Cd in solution. The relationship of tuber Cd concentrations to chloro-complexation in soil solution suggests that Cd species other than the free Cd2+ ion are involved in the transport through soil and uptake of Cd by plants.

Soil Research ◽  
2009 ◽  
Vol 47 (3) ◽  
pp. 305 ◽  
Author(s):  
Guodong Yuan

Soil plots on a pasture were amended with biosolids spiked with copper (Cu), nickel (Ni), or zinc (Zn), resulting in maximum concentrations of 181 mg Cu, 58 mg Ni, and 296 mg Zn/kg in soil. Soil solutions from the plots were obtained by centrifugation for chemical analyses, and free metal ion activities (Cu2+, Ni2+, Zn2+) were computed from the Windermere Humic Aqueous Model (WHAM). In the 3 years after biosolids amendment, the concentrations and activities of Cu, Ni, and Zn in soil solution increased with their amounts in biosolids. Copper and Ni concentrations in soil solution were higher than their critical concentrations recently reported in the literature. While Cu in soil solution was dominated by Cu-humic complexes, Ni2+ and Zn2+ were the majority species of the metals. Liming the soil plots to increase pH from 5.5 to ~7 greatly reduced the concentrations of the trace metals, particularly Zn; Cu2+, Zn2+, and Ni2+ were decreased by orders of magnitude 2–3, 2, and 1, respectively. Metal concentrations and activities fluctuated in the next 2 years as soil pH changed slightly and then after the use of elemental sulfur to acidify soil to pH ~6.5. Eight years after application of biosolids and through soil pH adjustment by lime and sulfur, Cu2+ and Zn2+ were very close to, and Ni2+ was a few times higher than, their corresponding baseline values. Maintaining a near neutral pH thus would be the key to keeping bioavailable metal concentrations low in a soil with an organic carbon content of 23.8 g/kg.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kechen Lv ◽  
Xinyu Yang ◽  
Tangqing Wu ◽  
Song Xu ◽  
Lanlan Liu ◽  
...  

Purpose High-silicon chromium iron (HSCI) has been used in ground grids in southern China, while there was a lack of study on its corrosion behavior in this soil environment. The purpose of this paper is to discover the corrosion of HSCI in acidic and alkaline soil solutions. Design/methodology/approach The original defects on the HSCI surface were observed using optical microscopy, and the corrosion behavior of the HSCI in the acidic and alkaline soil solutions were jointly detected using electrochemical measurements and scanning electron microscopy/energy dispersive spectrometer. Findings The results showed the corrosion rates of the HSCI in the acidic and alkaline soil solutions were limited, and the high contents of Cr and Si in matrix was responsible for its high corrosion resistance. The HSCI showed a similar corrosion tendency in the two solutions, while its corrosion rate in the acid soil solution was higher than that in the alkaline soil solution. The corrosion pits on the specimen surface were originated from the original defects in matrix, and the edges of the corrosion pits were more rounded than the original defects after 720 h immersion in the two solutions. The original defects in the HSCI matrix played a significant role in the corrosion process. Originality/value The paper discovered the corrosion evolution of HSCI in the acidic and alkaline soil solutions. What is more, the acceleration role of the original defects on the corrosion of the HSCI in the acidic and alkaline soil solutions was discovered in the paper. The results are beneficial for the material selection of ground grid equipment in engineering.


Soil Research ◽  
1995 ◽  
Vol 33 (3) ◽  
pp. 461 ◽  
Author(s):  
DM Wheeler ◽  
DC Edmeades

Thirteen trails were sampled to investigate the effects of depth, or the surface application of lime and phosphorus (P) fertilizer, on solution composition. Soil solutions were extracted by centrifuge from field moist soils within 24 h of sampling. Solution Ca, Mg, Na and K, Al, Mn and Fe concentrations generally decreased and Al, Mn and Fe concentrations generally increased with depth; although exceptions occurred. The largest decrease occurred in the first 25-50 mm of soil. Higher solution Al concentrations occurred in a band at a depth of between 50 and 100 mm in some soils. Lime generally increased solution pH and solution Ca, Mg and HCO3 concentrations, and reduced solution Al, Fe and Mn concentrations in the topsoils. In one soil (Matapiro silt loam) 2 years after lime was applied, lime increased solution pH down to a depth of 100 mm, Ca and HCO3 down to 75 mm and Mg down to 50 mm. Lime also decreased solution Al and Mn down to 75 mm and Fe down to 50 mm. In one series of trials, lime increased solution Ca concentrations at a depth of 50-100 mm 4 years after application in six out of the eight sites. In the same trial series, the application of P fertilizer increased solution P concentrations at 0-50 mm from a mean of 5 �M in the no-added P plots up to a mean of 56 �M at the highest P rate. The highest solution P concentration recorded was 194 �M. The increase in solution P concentrations for a given application of fertilizer P varied from 0.05 to 1.03 �M P per kg P ha-1 applied. Maximum pasture yield and 90% maximum yield occurred when solution P concentrations were about 28 and 14 �M respectively. Solution P concentrations determined from P adsorption isotherms were not a good indicator of solution P concentrations measured in soil. Solution pH was higher than soil pH (1:2.5 soil:water ratio, 2 h equilibration) with a solution pH of 6.0 corresponding to a soil pH in water of about 5.2.


1996 ◽  
Vol 42 (6) ◽  
pp. 880-887 ◽  
Author(s):  
N N Rehak ◽  
S A Cecco ◽  
J E Niemela ◽  
E N Hristova ◽  
R J Elin

Abstract We studied the stability and linearity of the AVL and Nova Mg and Ca ion-selective electrodes and the relation between the ionized Ca and ionized Mg results reported by each analyzer. The response of the electrodes to different concentrations of Mg and Ca was determined for saline solutions, aqueous solutions, and serum samples. The electrodes from both manufacturers demonstrated acceptable stability for the time of the study. The response of the electrodes was linear within the range specified by each manufacturer, but relative nonlinearity and the values for the linear limits differed between the AVL and Nova analyzers. The ionized Mg results varied with the concentration of Ca. The relation between ionized Ca and ionized Mg results was nonlinear and differed between the AVL and Nova electrodes. Intermethod comparison between the electrodes showed poor agreement for ionized Mg results, especially at low and high concentrations of total Ca and total Mg.


2017 ◽  
Vol 63 (No. 11) ◽  
pp. 491-497 ◽  
Author(s):  
Rutkowska Beata ◽  
Szulc Wiesław ◽  
Spychaj-Fabisiak Ewa ◽  
Pior Natalia

The aim of the study was to assess of plant available molybdenum (Mo) resources in the solutions of soils as well as to evaluate the effects of selected soil properties on changes of the Mo concentration in the soil solution. Sixty-two soil samples were investigated. The soil solutions were obtained by modified vacuum displacement method. The results showed that Mo concentrations in the soil solutions were much differentiated, ranging from 0.002 to approximately 0.100 µmol/L. Positive correlations were found between soil solution Mo concentration and soil pH as well as the contents of available phosphorous and organic carbon in soil. At the same time, Mo concentration was higher in the soil solutions obtained from soils with larger amounts of soil particles with diameter lesser than<br /> 0.02 mm. Among the analysed soil parameters in this study, soil pH is the most important factor that influences the Mo concentration in soil solution. Studies have shown that in acid sandy soils the amount of molybdenum found in the soil solution is too small to cover the nutritional requirements of the plants. This indicates the need of fertilization with this element. Regular liming of soils and fertilization with phosphorus can improve the availability of molybdenum to plants.


1985 ◽  
Vol 104 (2) ◽  
pp. 257-261 ◽  
Author(s):  
U. S. Sadan ◽  
M. S. Bajwa

SummaryA pot experiment studied the effect of gypsum and green manuring on equilibrium soil solution pH, pE, Mn concentration and Mn equilibrium in three sodic soils. Submergence decreased soil solution pH and increased Mn concentration in all the soils. Addition of gypsum with green manure further decreased soil solution pH and increased Mn concentration. Maximum Mn concentration in all the treatments was observed at 4 weeks of submergence in Kaheru soil and at 6 weeks of submergence in Jagjitpur and Langrian soil followed by a decline up to 12 weeks. In spite of wide variations in pH, pE and Mn concentration in soil solutions, the solubility of Mn after peak values appeared to be mainly controlled by the MnC03-Mn2+ system irrespective of the treatments, and the Mn2O3-Mn3O4 system appeared to operate after 2 weeks of submergence in the control and gypsum-treated soils.


2021 ◽  
Vol 97 (4) ◽  
Author(s):  
Lucas Dantas Lopes ◽  
Jingjie Hao ◽  
Daniel P Schachtman

ABSTRACT Soil pH is a major factor shaping bulk soil microbial communities. However, it is unclear whether the belowground microbial habitats shaped by plants (e.g. rhizosphere and root endosphere) are also affected by soil pH. We investigated this question by comparing the microbial communities associated with plants growing in neutral and strongly alkaline soils in the Sandhills, which is the largest sand dune complex in the northern hemisphere. Bulk soil, rhizosphere and root endosphere DNA were extracted from multiple plant species and analyzed using 16S rRNA amplicon sequencing. Results showed that rhizosphere, root endosphere and bulk soil microbiomes were different in the contrasting soil pH ranges. The strongest impact of plant species on the belowground microbiomes was in alkaline soils, suggesting a greater selective effect under alkali stress. Evaluation of soil chemical components showed that in addition to soil pH, cation exchange capacity also had a strong impact on shaping bulk soil microbial communities. This study extends our knowledge regarding the importance of pH to microbial ecology showing that root endosphere and rhizosphere microbial communities were also influenced by this soil component, and highlights the important role that plants play particularly in shaping the belowground microbiomes in alkaline soils.


Botany ◽  
2011 ◽  
Vol 89 (5) ◽  
pp. 289-299 ◽  
Author(s):  
Marie-Claude Moisan ◽  
Jean Rivoal

We have developed an extraction procedure that improves the stability of potato ( Solanum tuberosum L.) tuber hexokinase (HK) after extraction. Using this protocol, we showed that at least four HK isoforms are present in this tissue, and they can be separated by hydrophobic-interaction chromatography on a butyl-Sepharose™ 4 Fast Flow column. One of the main HK isoforms was purified to homogeneity using further chromatographic separations on red dye, DEAE Fractogel, hydroxyapatite, cibacron blue, and MonoQ matrices. HK-specific activity of this fraction (10.2 U·mg protein–1) corresponds to an enrichment of more than 5500-fold, with a yield of 0.9%. This is the highest reported HK-specific activity from a plant source. The purified enzyme consisted of a monomer with a subunit apparent Mr of 51 kDa when analyzed by SDS–PAGE. This polypeptide was recognized by affinity-purified anti- Solanum chacoense Bitt. recombinant HK IgGs. The protein was digested with trypsin and its digestion products were subjected to MS – MS sequencing after HPLC separation. The sequences of these tryptic peptides matched the predicted coding sequence of the S. tuberosum HK1 gene with a coverage of 57%. Examination of the kinetic properties of the purified protein HK1 indicates that it may be regulated by the internal O2 concentration of the tuber because of its sensitivity to acidic pHs and inhibition by ADP.


2014 ◽  
Vol 4 ◽  
Author(s):  
Verónica Asensio Fandiño ◽  
Flora A. Vega ◽  
Rubén Forján ◽  
Emma F. Covelo

The sorption capacity for Ni, Pb and Zn of mine tailings soil with and without reclamation treatment (tree planting and waste amendment) was evaluated using the batch adsorption technique. It is important to determine the capacity of waste-amended soils to retain Ni, Pb and Zn, as the sludges used usually have high concentrations of these metals. The results obtained in the present study showed that the untreated mine tailings soil had a low capacity for Ni, Pb and Zn retention. The sorption capacity for Pb increased significantly in all of the treated soils, without any significant differences between them. The treatment that most increased the sorption capacity for Ni and Zn was planting with trees and amending with waste simultaneously, as this increased the concentration of both organic and inorganic carbon, exchangeable calcium, soil pH and effective cation exchange capacity


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