Complexation of Lead in Model Solutions of Humic Acid: Heterogeneity and Effects of Competition with Copper, Nickel, and Zinc

2006 ◽  
Vol 3 (4) ◽  
pp. 276 ◽  
Author(s):  
Ismail I. Fasfous ◽  
C. L. Chakrabarti ◽  
John Murimboh ◽  
Tahir Yapici
Keyword(s):  
Humic Acid ◽  
Trace Metals ◽  
Trace Metal ◽  
Humic Substances ◽  
Metal Concentration ◽  
Natural Waters ◽  
Metal Bioavailability ◽  
Copper Nickel ◽  
Model Solutions ◽  
Equilibrium Function

Environmental Context. Metal bioavailability and toxicity are often related to free metal concentration rather than total metal concentration. Humic substances are chemically and physically heterogeneous complexants for metals in natural waters, and play an important role in trace metal transport, fate, and bioavailability. Metal bioavailability, which depends on chemical speciation of metals, is greatly influenced by the presence of other trace metals and major cations in natural waters. In this work, the effects of heterogeneity of humic substances, and of competition of trace metals on lead speciation in model solutions have been studied to gain a better understanding of these effects on complexation of trace metal lead and its bioavailability. Abstract. Physicochemical heterogeneity of a well characterized humic acid (HA) in its complexation with a trace metal lead in model solutions was investigated using pseudo-polarography at a stationary mercury drop electrode, and the differential equilibrium function (DEF) of Pb(ii)–HA complexes was determined. The complexation of Pb(ii) by HA was determined by taking into account the dependence of the strength of the binding on the metal (Pb) loading. Also investigated were the effects of competition of the trace metals copper, nickel, and zinc on the DEF of Pb(ii)–HA complexes in model solutions. The results showed that these trace metals competed with trace metal lead for binding by HA even when present at the same concentrations as that of lead.

Investigation of V(V) interaction with Humic Acid in aqueous solution using anion-exchange Ion Chromatography

2021 ◽  
Author(s):  
Lucija Knežević ◽  
Elvira Bura-Nakić
Keyword(s):  
Humic Acid ◽  
Ionic Strength ◽  
Anion Exchange ◽  
Ion Chromatography ◽  
Natural Waters ◽  
Detection System ◽  
Chemical Species ◽  
Research Report ◽  
Complexing Agent ◽  
Model Solutions

<p>The distribution of V chemical species in natural waters has been scarcely studied mainly due to its high reactivity and wide variety of co-existing forms depending on number of factors including metal concentration, pH, Eh, ionic strength, the presence of complexing ligands etc. <sup>1</sup> Importance of V speciation studies lies in the dependence of toxicity and bioavailability upon different chemical species that V takes form of in natural waters, with V(V) being most toxic and soluble <sup>4</sup>. Although thermodynamic calculations predict V(V) as dominant species in well oxidized marine environments, V(IV) is also reported to be present due to its ability to form stable complexes with Dissolved Organic Matter (DOM) related ligands found in natural waters <sup>2–6</sup>. Furthermore, previous research report that Humic Acid (HA) acts as an adsorbent and complexing agent for many trace metals (Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, Fe<sup>2+</sup>). However, HA impact on V speciation and potential removal from the water column of natural aquatic systems is still unclear <sup>7</sup>.</p><p>Interaction of V(V) with HA was investigated in model solutions under different conditions using anion-exchange based Ion Chromatography with UV/Vis detection system. The goal of the research was to mimic natural conditions, as experimentally possible, in order to assess likely contribution of HA to changes in V speciation and potential removal from the solution by adsorption on HA colloids. Temporal study on V(V) reduction kinetics was conducted using strong chelator (EDTA) which was added in the filtrated solution prior to measurement in order to stabilize distribution of V species in the model solutions. Removal of V(V) from the solution on HA particles was quantified using calibration curves. Desorption experiments were performed with the addition of EDTA in un-filtrated solutions 24 hours before measurement.</p><p>Research showed that V interaction with HA is highly dependant on ionic strength of solution as well as ratios between V(V) and HA present in the solution. Desorption experiments showed almost complete recovery of V in the solutions with higher ionic strength, mainly in the form of V(IV). Observed reduction and removal of V(V) from the solution on the pH of natural waters suggest high impact of DOM on V speciation and consequently its toxicity and bioavailability.  </p><p><strong>References:</strong></p><p>1           P. N. Linnik and R. P. Linnik, Russ. J. Gen. Chem., 2018, <strong>88</strong>, 2997–3007.</p><p>2           J. P. Gustafsson, Appl. Geochemistry, 2019, <strong>102</strong>, 1–25.</p><p>3           P. Bernárdez, N. Ospina-Alvarez, M. Caetano and R. Prego, Environ. Chem., 2013, <strong>10</strong>, 42–53.</p><p>4           D. Wang and S. A. Sañudo Wilhelmy, Mar. Chem., 2009, <strong>117</strong>, 52–58.</p><p>5           K. Hirayama, S. Kageyama and N. Unohara, Analyst, 1992, <strong>117</strong>, 13–17.</p><p>6           D. Wang and S. A. Sañudo-Wilhelmy, Mar. Chem., 2008, <strong>112</strong>, 72–80.</p><p>7           Y. Yu, M. Liu and J. Yang, Chem. Ecol., 2018, <strong>34</strong>, 548–564.</p>

scholarly journals Evaluation of Trace Metal Profile inCymbopogon validusandHyparrhenia hirtaUsed as Traditional Herbs from Environmentally Diverse Region of Komga, South Africa

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Babalwa Tembeni ◽  
Opeoluwa O. Oyedeji ◽  
Ikechukwu P. Ejidike ◽  
Adebola O. Oyedeji
Keyword(s):  
South Africa ◽  
Trace Metals ◽  
Trace Metal ◽  
Metal Concentration ◽  
Trace Metal Concentration ◽  
Eastern Cape ◽  
Metal Concentrations ◽  
Herbal Products ◽  
Plant Parts ◽  
Permissible Limits

FAAS was used for the analysis of trace metals in fresh and dry plant parts ofCymbopogon validusandHyparrhenia hirtaspecies with the aim of determining the trace metals concentrations in selected traditional plants consumed in Eastern Cape, South Africa. The trace metal concentration (mg/kg) in the samples of dryCymbopogon validusleaves (DCVL) showed Cu of12.40±1.000; Zn of2.42±0.401; Fe of2.50±0.410; Mn of1.31±0.210; Pb of3.36±0.401 mg/kg, while the samples of freshHyparrhenia hirtaflowers (FHHF) gave Cu of9.77±0.610; Zn of0.70±0.200; Fe of2.11±0.200; Mn of1.15±0.080; Pb of3.15±0.100 mg/kg. Abundance of metal concentrations follows the order: Cu > Fe > Pb > Mn > Zn in the flower samples ofCymbopogon validusandHyparrhenia hirtaspecies. The concentrations of trace metals in both plant parts were below the permissible limits (PL) set by WHO. It is suggested that pharmacovigilance be carried out periodically to improve the quality, safety, and efficiency of various herbal products.

Trace metals in sediments from the Yarra River

1982 ◽  
Vol 33 (5) ◽  
pp. 761 ◽  
Author(s):  
M Ellaway ◽  
BT Hart ◽  
R Beckett
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Metal Concentration ◽  
Estuarine Sediments ◽  
Trace Metal Concentration ◽  
Metal Concentrations ◽  
Lead And Zinc ◽  
Sediment Fraction ◽  
Copper Lead ◽  
Yarra River

The distribution and phase association of iron, manganese, cadmium, copper, lead and zinc in bottom sediments taken from the freshwater, estuarine and bay regions of the Yarra River were investigated. The fraction of the estuarine sediments smaller than 20 �m contained substantially higher concentrations of cadmium, copper, lead and zinc than did the corresponding sediment fraction from the upper river and bay regions. Sequential chemical extraction revealed that most of the variability in the trace metal concentration of these sediments was associated with changes in the reducible phase. A substantial increase in trace metal concentrations occurred in going from river to estuarine sediments. For example, the lead concentration increased approximately eightfold (43-375 �g g-1), the zinc fourfold (122-447 �g g-1) and the copper almost twofold (64-106 �g g-1). This was attributed to coagulation and sedimentation of trace-metal- enriched iron and manganese oxides in the estuarine region. The subsequent decrease in metal concentrations in the bay sediments was due to either physical dilution of the contaminated sedlment with material of lower metal concentration or remobilizatlon of the trace metals from sediments deposited in the bay.

scholarly journals Evaluation of the DGT technique for selective measurement of aluminium and trace metal concentrations in an acid drainage-impacted coastal waterway

2017 ◽  
Vol 19 (5) ◽  
pp. 742-751 ◽  
Author(s):  
Amir Houshang Shiva ◽  
Peter R. Teasdale ◽  
David T. Welsh ◽  
William W. Bennett
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Natural Waters ◽  
Metal Concentrations ◽  
Acid Drainage

DGT samplers with different binding layers (Chelex, Metsorb and mixed Chelex–Metsorb) were evaluated for measurement of Al and trace metals in four natural waters with a range of pH.

scholarly journals Adsorptive and Coagulative Removal of Trace Metals from Water Using Surface Modified Sawdust-Based Cellulose Nanocrystals

J ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 193-205
Author(s):  
Opeyemi A. Oyewo ◽  
Sam Ramaila ◽  
Lydia Mavuru ◽  
Taile Leswifi ◽  
Maurice S. Onyango
Keyword(s):  
Trace Metals ◽  
Adsorption Capacity ◽  
Cellulose Nanocrystals ◽  
Inductively Coupled Plasma ◽  
Electrostatic Interactions ◽  
Natural Waters ◽  
Maximum Adsorption Capacity ◽  
Solution Ph ◽  
Major Drawback ◽  
Surface Modified

The presence of toxic metals in surface and natural waters, even at trace levels, poses a great danger to humans and the ecosystem. Although the combination of adsorption and coagulation techniques has the potential to eradicate this problem, the use of inappropriate media remains a major drawback. This study reports on the application of NaNO2/NaHCO3 modified sawdust-based cellulose nanocrystals (MCNC) as both coagulant and adsorbent for the removal of Cu, Fe and Pb from aqueous solution. The surface modified coagulants, prepared by electrostatic interactions, were characterized using Fourier transform infrared, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive spectrometry (SEM/EDS). The amount of coagulated/adsorbed trace metals was then analysed using inductively coupled plasma atomic emission spectroscopy (ICP-AES). SEM analysis revealed the patchy and distributed floccules on Fe-flocs, which was an indication of multiple mechanisms responsible for Fe removal onto MCNC. A shift in the peak position attributed to C2H192N64O16 from 2θ = 30 to 24.5° occurred in the XRD pattern of both Pb- and Cu-flocs. Different process variables, including initial metal ions concentration (10–200 mg/L), solution pH (2–10), and temperature (25–45 °C) were studied in order to investigate how they affect the reaction process. Both Cu and Pb adsorption followed the Langmuir isotherm with a maximum adsorption capacity of 111.1 and 2.82 mg/g, respectively, whereas the adsorption of Fe was suggestive of a multilayer adsorption process; however, Fe Langmuir maximum adsorption capacity was found to be 81.96 mg/g. The sequence of trace metals removal followed the order: Cu > Fe > Pb. The utilization of this product in different water matrices is an effective way to establish their robustness.

scholarly journals Marine ammonia-oxidising archaea and bacteria occupy distinct iron and copper niches

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Roxana T. Shafiee ◽  
Poppy J. Diver ◽  
Joseph T. Snow ◽  
Qiong Zhang ◽  
Rosalind E. M. Rickaby
Keyword(s):  
Comparative Genomics ◽  
Trace Metals ◽  
Trace Metal ◽  
Ammonia Oxidation ◽  
Testable Hypothesis ◽  
Niche Separation ◽  
Toxicity Threshold ◽  
Geologic Time ◽  
Additional Explanation ◽  
Ammonia Oxidising Archaea

AbstractAmmonia oxidation by archaea and bacteria (AOA and AOB), is the first step of nitrification in the oceans. As AOA have an ammonium affinity 200-fold higher than AOB isolates, the chemical niche allowing AOB to persist in the oligotrophic ocean remains unclear. Here we show that marine isolates, Nitrosopumilus maritimus strain SCM1 (AOA) and Nitrosococcus oceani strain C-107 (AOB) have contrasting physiologies in response to the trace metals iron (Fe) and copper (Cu), holding potential implications for their niche separation in the oceans. A greater affinity for unchelated Fe may allow AOB to inhabit shallower, euphotic waters where ammonium supply is high, but competition for Fe is rife. In contrast to AOB, AOA isolates have a greater affinity and toxicity threshold for unchelated Cu providing additional explanation to the greater success of AOA in the marine environment where Cu availability can be highly variable. Using comparative genomics, we predict that the proteomic and metal transport basis giving rise to contrasting physiologies in isolates is widespread across phylogenetically diverse marine AOA and AOB that are not yet available in pure culture. Our results develop the testable hypothesis that ammonia oxidation may be limited by Cu in large tracts of the open ocean and suggest a relatively earlier emergence of AOB than AOA when considered in the context of evolving trace metal availabilities over geologic time.

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