Heavy Metals In Natural Waters Research Articles

Heavy metals in centralized drinking water sources of the Yangtze River: A comprehensive study from a basin-wide perspective

Water quality in the Yangtze River Basin (YRB) has received considerable attention because it supplies water to 400 million people. However, the trends, sources, and risks associated with heavy metals (HMs) in water of centralized drinking water sources (CDWSs) in the YRB region are not well understood due to the lack of high-frequency, large-scale monitoring data. Moreover, research on the factors affecting the transportation of HMs in natural water are limited, all of which significantly reduce the effectiveness of CDWSs management. Therefore, this study utilized data on 11 HMs and water quality from 114 CDWSs, covering 71 prefecture-level cities (PLC) in 15 provinces (cities), to map unprecedented geospatial distribution of HMs in the YRB region and examine their concentrations in relation to water chemistry parameters. The findings revealed that the frequency of detection (FOD) of 11 HMs ranged from 28.59% (Hg) to 99.64% (Ba). The mean concentrations are ranked as follows: Ba (40.775 μg/L) > B (21.866 μg/L) > Zn (5.133 μg/L) > V (2.668 μg/L) > Cu (2.049 μg/L) > As (1.989 μg/L) > Mo (1.505 μg/L) > Ni (1.108 μg/L) > Sb (0.613 μg/L) > Pb (0.553 μg/L) > Hg (0.002 μg/L). Concentrations of Zn, As, Hg, Pb, Mo, Sb, Ni, and Ba exhibited decreasing trends from 2018 to 2022. Human activities, including industrial and agricultural production, have led to higher pollution levels in the midstream and downstream of the river than in its upstream. Additionally, the high concentrations of Ba and B are influenced by natural geological factors. Anion concentrations and nutrient levels, play a significant role in the transport of HMs in water. Probabilistic health risk assessment indicates that As, Ba, and Sb pose a potential carcinogenic risk. Additionally, non-carcinogenic risk to children under extreme conditions should also be considered.

Adsorption of Heavy Metals on Alkali-Activated Zeolite Foams.

Elevated concentrations of heavy metals in natural waters can cause significant ecological problems. It is therefore essential to ensure their removal from any water discharged into the environment immediately, especially in case of an accident, where there is a risk of releasing large quantities or high concentrations. The aim of this paper is to test a newly developed adsorbent for the removal of heavy metals from aqueous solutions-in particular, it is very fast adsorption, and thus efficiency, during clean-ups. The alkali-activated foamed zeolite adsorbent was laboratory-prepared and -tested in both batch and flow-through arrangements on single and multi-component solutions and compared with natural zeolite. The experimental setup for batch adsorption consisted of a set of samples and solutions containing iron, cobalt, manganese, zinc and nickel. The samples were put on a horizontal shaker with a 500 mg adsorbent loading in a 50 mL solution. The column adsorption experimental setup consisted of a glass column with an inside diameter of 15 mm and a bed length of 165 mm. A measured amount of each adsorbent was added to the column to achieve a filter fixed-bed height of 160 mm. The high efficiency of the tested adsorbent on various heavy metals was confirmed. The adsorbent has a high potential for use in decontamination processes, water protection and landscape revitalization. Due to its rapid precipitation and subsequent fixation of metal cations in the form of insoluble oxide or hydroxide, it can be used as an emergency adsorbent, the great advantage of which is its low production cost and natural origin.

Biosorción de Cu(II) sobre cáscaras de maní y maltas residuales. Incorporación de la biomasa contaminada en matrices cerámicas

La presencia de metales pesados en los cursos naturales de agua, tiene efectos nocivos sobre la salud de muchas especies biológicas y sobre el medio ambiente. Los biosorbentes son ampliamente reconocidos como adsorbentes de bajo costo porque son abundantes en la naturaleza o por ser materiales de desecho de la agroindustria. En el presente trabajo se estudia la remoción de iones de Cu (II) en solución acuosa, utilizando cáscaras de maní y residuos de cebada de la producción de cerveza como materiales adsorbentes. Además se plantea la posibilidad de inmovilizar el metal contaminante junto a la biomasa en matrices cerámicas, comenzando por el estudio de la temperatura óptima de cocción. Se realizó una exhaustiva caracterización de ambas biomasas, y se analizaron numerosas variables en el proceso de biosorción en búsqueda de condiciones que maximicen la capacidad adsorbente de las mismas. Los resultados muestran que las cáscaras de maní logran remociones de hasta el 40% del metal, mientras que los residuos de cebada no logran superar el 2,3% de remoción. En base a los resultados obtenidos y dado que ambas biomasas son un subproducto industrial abundante y de bajo costo, se sugiere a la biosorción mediante cáscaras de maní como un proceso efectivo y económico para la remoción de iones de cobre en aguas contaminadas. A su vez, se establecen temperaturas de 950°C-1000ºC como rango óptimo de cocción de las matrices cerámicas, para analizar la inmovilización de los metales removidos.

Investigation of Complex Formation Process of Copper with Macromolecular Organic Substances, Isolated from Natural Waters

Natural macromolecular organic substances-fulvic acids take an active part in complex formation processes and stipulate migration forms of heavy metals in natural waters The calculation of the migration forms of heavy metals is one of the problematic issue of the contemporary chemistry, which couldn’t be solved without using the conditional stability constants of fulvate complexes. In spite of researches, experimental data on stability constants of complex compounds of fulvic acids with heavy metals ( among them copper) are heterogeneous and they differ in several lines from each other. One of the reason of such condition is ignoring an average molecular weight of the associates of fulvic acids, which finally causes the wrong results. Complex formation process between copper (II) and fulvic acids was studied by the solubility method at pH=9.0. Cu(OH)2 suspension was used as a solid phase. Fulvic acids were isolated from Paravani lake by the adsorption –chromatographic method. In this article is shown that, during complex formation process every 1/4 part of an associate of fulvic acids(Mw=7610), inculcates into copper's inner coordination sphere as an integral ligand, so it may assume, that the average molecular weight of the associate of fulvic acids which takes part in complex formation process equals to 1903. This part of the associate of fulvic acids was conventionally called an“active associate".The average molecular weight of the“active associate”was used for determination the composition of copper fulvate complex, the concentration of free ligand and stability constant, which equals to 2,25x107 

Modeling Water Pollution under Different Scenarios of Zinc Load on the Nizhnekamskoe Reservoir Watershed

The potentialities of the physically-based model ECOMAG-HM for the study of zinc content formation regularities in the Nizhnekamskoe Reservoir basin have been demonstrated. The basin is characterized by high concentrations of heavy metals in natural waters due to the significant content of ore-forming elements in rocks and a high level of economic development. The daily zinc concentrations have been calculated, and the maps of mean annual zinc concentrations in the river network have been compiled. Local areas of the catchment not covered by hydrochemical observations and showing a significant level of river water contamination by zinc have been identified. The fields of the genetic components of zinc hydrochemical runoff have been calculated. The contribution of anthropogenic sources to the zinc runoff formation has been estimated, and it has been established that, with the current level of anthropogenic load, the contribution of wastewater point discharges does not exceed 4%. The scenarios and consequences of increasing the amount of zinc discharged as part of wastewater are considered. The time scale of the catchment self-purification from zinc has been evaluated. The results show that, in the absence of external impacts on the catchment area, a decrease in zinc content in river waters over a 400-year period will be about as little as 8%.

Synthesis of MnCo2O4 nanoparticles as modifiers for simultaneous determination of Pb(II) and Cd(II)

The porous spinel oxide nanoparticles, MnCo2O4, were synthesized by citrate gel combustion technique. Morphology, crystallinity and Co/Mn content of modified electrode was characterized and determined by Fourier transform infra-red spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), X-ray diffraction pattern analysis (XRD), simultaneous thermogravimetry and differential thermal analysis (TG/DTA). Nanoparticles were used for modification of glassy carbon electrode (GCE) and new sensor was applied for simultaneous determination of Pb(II) and Cd(II) ions in water samples with the linear sweep anodic stripping voltammetry (LSASV).The factors such as pH, deposition potential and deposition time are optimized. Under optimal conditions the wide linear concentration range from 0.05 to 40 μmol/dm3was obtained for Pb(II), with limit of detection (LOD) of 8.06 nmol/dm3 and two linear concentration ranges were obtained for Cd(II), from 0.05 to 1.6 μmol/dm3 and from 1.6 to 40 μmol/dm3, with calculated LOD of 7.02 nmol/dm3. The selectivity of the new sensor was investigated in the presence of interfering ions. The sensor is stable and it gave reproducible results. The new sensor was succesfully applied on determination of heavy metals in natural waters.

Solid-phase microextraction of heavy metals in natural water with a polypyrrole/carbon nanotube/1, 10–phenanthroline composite sorbent material

A simple and sensitive method for simultaneous microextraction and determination of heavy metals using a new direct immersion solid-phase microextraction (DI–SPME) sorbent material combined with inductively coupled plasma mass spectrometry (ICP–MS) was investigated. In this method, sorbent coating composites were prepared by simultaneous electropolymerization of pyrrole on pencil lead in the presence of carbon nanotubes (CNTs) and different metal chelating ligands. Among the coatings evaluated, a polypyrrole coating with entrapped CNTs and the chelator 1, 10 phenanthroline allowed the determination of silver, cadmium, cobalt, iron, nickel, lead, and zinc. Parameters influencing microextraction efficiency including pH, extraction time, and desorption time were optimized. The linear dynamic ranges were 1–1000 μg L−1 for Ag, 1–750 μg L−1 for Cd, Pb, and Zn, and 1–500 μg L−1 for Co, Fe, and Ni with limits of detection of 0.012–0.163 μg L−1 and limits of quantification of 0.039–0.542 μg L−1. The relative standard deviations (RSDs, n = 5) ranged from 1.85% to 5.01%. The effect of inorganic interferences on the determination of the heavy metals also was examined and finally, the method was successfully applied for the determination of heavy metals in real water samples.

New version of calculation of stability constant of metal–fulvate complexes on the example of zinc fulvate

Natural macromolecular organic substances—fulvic acids—take an active part in complex formation processes and stipulate migration forms of heavy metals in natural waters. In spite of researches, experimental data on stability constants of complex compounds of fulvic acids with heavy metals (among them zinc) are heterogenous and they differ in several lines from each other. One of the reasons of such condition is ignoring an average molecular weight of the associates of fulvic acids, which finally causes the wrong results. Complex formation process between zinc (II) and fulvic acids was studied by the solubility method at pH = 8.0. ZnO suspension was used as a solid phase. Fulvic acids were isolated from Paravani lake by the adsorption chromatographic method. This article shows that during the complex formation process, every 1/5 part of an associate of fulvic acids inculcates into zinc’s (II) inner coordination sphere, as an integral ligand. So it may assume that the average molecular weight of the associate of fulvic acids which takes part in complex formation process equals to 1252. This part of the associate of fulvic acids was conventionally called an “active associate.” The average molecular weight of the “active associate” was used for determining the composition of zinc fulvate complex, the concentration of free ligand and stability constant, which equals to $$1.6 \times 10^{4}$$ .

Carbon nanotubes as sorbent material for removal of cadmium

Heavy metal ions are highly toxic industrial pollutants of which maximum levels are regulated such as in the ppb range for drinking water. Elevated levels of heavy metals in natural water may have a detrimental effect on both human health and the environment. Carbon nanotubes (CNTs) have been investigated widely over last two decades for numerous potential applications to exert considerable technological impact on future miniaturized, compact, cost effective, and efficient devices. The novel tubular structures of CNTs became one of the most valuable materials in water management due to their distinct features such as inertness, porous structure, low density, and affinity for pollutants. Such astonishing features help make them overcome the shortcomings of activated carbon. In this research, we focused on the synthesis, characterization, and evaluation of multi walled carbon nanotubes (MWCNTs) as adsorbent for removal of cadmium. MWCNTs synthesized in size range of 60–70nm (width) and length in microns using chemical vapour deposition (CVD) method were characterized by the field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Raman spectroscopic analyses. These MWCNTs when explored for the removal of cadmium ions (Cd2+) from their aqueous solutions exhibited a maximum adsorption capacity of 181.8mg/g with the Langmuir isotherm model (R2=0.98). The findings of this research work project that CNTs can play a vital role as nanoadsorbent towards heavy metals management.

СИЛІКАГЕЛЬ, МОДИФІКОВАНИЙ ТІОСЕМИКАРБАЗОНОМ Α-НАФТОХІНОНУ ДЛЯ СОРБЦІЙНО-ФОТОМЕТРИЧНОГО ВИЗНАЧЕННЯ РТУТІ (II)

A sorption-photometric test method for preconcentration and determination of mercury (II) was developed using silica gel modified with 1,2-naphthoquinone thiosemicarbazone. Modification of silica gel with a reagent was carried out from the chloroform-hexane solution for 3 hours. Pocket photometer was used for the measurement of reflected (transmitted) light from silica modified after sorption of thiosemicarbazonate of Hg(II). The adsorption capacity of the sorbent has been found to be 35 μmol g-1 for 1,2-naphthoquinone thiosemicarbazone. The effects of pH, sorption time, the volume of aqueous solution were studied. In the optimal conditions (pH 3.0; 5 min; 25°C) the extraction recovery of mercury is 90–95%. The range of concentrations of mercury (ІІ) is 50–600 µg L–1, the detection limit (S/N = 3) is 23 µg L–1. The method is tested in the model tap and natural water samples, relative standard deviation for 50 μg L−1 of Hg(II) is below 9.0 % (n = 3). The interference effect of the most common heavy metals in natural water, as Fe (III), Zn (II) and Mn (II) ions were studied. The EDTA solution was added for the binding of these metals, which forms strong colorless complexes with EDTA. We have shown that in the presence of 0,01 M EDTA solution Fe (III), Zn (II) and Mn (II) ions, each up to 500 μg L−1, do not interfere with the determination of mercury (II) at its content of 50 μg L−1. The method can be used for the determination of mercury in the sewage of various industries and natural waters with its high content. The proposed method is inexpensive, simple, fast, and environmentally friendly for the determination of the micro quantities of mercury (II) in the water samples.

Light-induced reduction of silver ions to silver nanoparticles in aquatic environments by microbial extracellular polymeric substances (EPS)

Microbial extracellular polymeric substances (EPS) widely exist in natural environments and affect the migration and transformation of pollutants in aquatic environments. Previous works report that EPS have some reducing functional groups and can reduce heavy metals. However, because of the weak reducing capability of EPS, the reduction of heavy metals by EPS without cells is extremely slow, and its effect on heavy metals species is insignificant. In this work, the accelerated reduction of silver ions (Ag+) by EPS from Shewanella oneidensis MR-1 under illumination was investigated. UV–visible spectroscopy, transmission electron microscopy (TEM) coupled with an energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) were used to confirm the formation of silver nanoparticles (AgNPs) via the reduction of Ag+ by EPS under light illumination. The Ag+ reduction by EPS follows pseudo-first-order kinetics under both visible and UV light, and the light irradiation can significantly accelerate AgNPs formation. On the one hand, visible light can excite AgNPs for their surface plasma resonance (SPR) and accelerate the electrons from the EPS to adjacent Ag+. On the other hand, EPS molecules may be excited by UV light to produce strong reducing species, which enhance Ag+ reduction. Moreover, pH, dissolved oxygen were found to affect the formation of AgNPs by EPS. This work proves the reducing capability of EPS on the reduction of Ag+, and this process can be accelerated under light illumination, which may affect the speciation and transformation of heavy metals in natural waters.

Effect of titanium dioxide nanoparticles on copper toxicity to Daphnia magna in water: Role of organic matter

Inevitably released into natural water, titanium dioxide nanoparticles (nano-TiO2) may affect the toxicity of other contaminants. Ubiquitous organic matter (OM) may influence their combined toxicity, which has been rarely reported. This study investigated the effect of nano-TiO2 on Cu toxicity to Daphnia magna and the role of OM (dissolved or particle surface bound) in inducing combined effects. The effect of nano-TiO2 on heavy metal accumulation depended on the adsorption capacity for heavy metals of nano-TiO2 and the uptake of nano-TiO2–metal complexes by organisms. Nano-TiO2 significantly decreased Cu accumulation in D. magna, but the reducing effect of nano-TiO2 was eliminated in the presence of humic acid (HA, a model OM). In the Cu and HA solution, nano-TiO2 slightly affected the bioavailability of Cu2+ and Cu–HA complexes and thus slightly influenced Cu toxicity. The nanoparticle surface-bound HA reduced the effect of nano-TiO2 on the speciation of the accumulated Cu; therefore, the combined effects of nano-TiO2 and Cu on biomarkers similarly weakened. HA-altered Cu speciation may be the main factor responsible for the influence of HA on the combined effects of nano-TiO2 and Cu. This study provides insights into the combined effects of nano-TiO2 and heavy metals in natural water.

A high-throughput solid-phase extraction microchip combined with inductively coupled plasma-mass spectrometry for rapid determination of trace heavy metals in natural water

Herein, a hyphenated system combining a high-throughput solid-phase extraction (htSPE) microchip with inductively coupled plasma-mass spectrometry (ICP-MS) for rapid determination of trace heavy metals was developed. Rather than performing multiple analyses in parallel for the enhancement of analytical throughput, we improved the processing speed for individual samples by increasing the operation flow rate during SPE procedures. To this end, an innovative device combining a micromixer and a multi-channeled extraction unit was designed. Furthermore, a programmable valve manifold was used to interface the developed microchip and ICP-MS instrumentation in order to fully automate the system, leading to a dramatic reduction in operation time and human error. Under the optimized operation conditions for the established system, detection limits of 1.64–42.54 ng L−1 for the analyte ions were achieved. Validation procedures demonstrated that the developed method could be satisfactorily applied to the determination of trace heavy metals in natural water. Each analysis could be readily accomplished within just 186 s using the established system. This represents, to the best of our knowledge, an unprecedented speed for the analysis of trace heavy metal ions.

Simultaneous Determination of Trace Heavy Metals in Natural Water by Portable Metal Analyzer

The analysis index of the portable metal analyzer for trace heavy metals in natural water based on anodic stripping voltammetry (ASV) were performed. Simultaneous determination and monovariated analysis of trace heavy metals were investigated both subsequently. The reasons of disturbance in analysis were also discussed. The addition of Ga (II) was testified that can eliminate the formation of the Cu-Zn intermetallic compound.

Разработка и обоснование региональных показателей качества воды по содержанию тяжелых металлов для водных объектов бассейна B. Kамы

The paper presents a new methodology for establishing regional water quality standards for the Upper Kama water bodies. Water bodies of the Upper Kama Basin are receiving wastewater from one of the largest industrial complexes of the Kama basin – Solikamsk-Berezniki industrial hub. The approach takes into account factors that determine the content of heavy metals in natural waters and the spatial/temporal variability of their content in the water bodies of the Upper Kama basin. The developed approach is implemented in establishment of regional water quality standards for the Upper Kama basin.

A dipole-assisted solid-phase extraction microchip combined with inductively coupled plasma-mass spectrometry for online determination of trace heavy metals in natural water

We employed a polymeric material, poly(methyl methacrylate) (PMMA), for fabricating a microdevice and then implanted the chlorine (Cl)-containing solid-phase extraction (SPE) functionality into the PMMA chip to develop an innovative on-chip dipole-assisted SPE technique. Instead of the ion-ion interactions utilized in on-chip SPE techniques, the dipole-ion interactions between the highly electronegative C-Cl moieties in the channel interior and the positively charged metal ions were employed to facilitate the on-chip SPE procedures. Furthermore, to avoid labor-intensive manual manipulation, a programmable valve manifold was designed as an interface combining the dipole-assisted SPE microchip and inductively coupled plasma-mass spectrometry (ICP-MS) to achieve the fully automated operation. Under the optimized operation conditions for the established system, the detection limits for each analyte ion were obtained based on three times the standard deviation of seven measurements of the blank eluent solution. The limits ranged from 3.48 to 20.68 ng L(-1), suggesting that this technique appears uniquely suited for determining the levels of heavy metal ions in natural water. Indeed, a series of validation procedures demonstrated that the developed method could be satisfactorily applied to the determination of trace heavy metals in natural water. Remarkably, the developed device was durable enough to be reused more than 160 times without any loss in its analytical performance. To the best of our knowledge, this is the first study reporting on the combination of a dipole-assisted SPE microchip and elemental analysis instrument for the online determination of trace heavy metal ions.

A DGT technique for plutonium bioavailability measurements.

The toxicity of heavy metals in natural waters is strongly dependent on the local chemical environment. Assessing the bioavailability of radionuclides predicts the toxic effects to aquatic biota. The technique of diffusive gradients in thin films (DGT) is largely exploited for bioavailability measurements of trace metals in waters. However, it has not been applied for plutonium speciation measurements yet. This study investigates the use of DGT technique for plutonium bioavailability measurements in chemically different environments. We used a diffusion cell to determine the diffusion coefficients (D) of plutonium in polyacrylamide (PAM) gel and found D in the range of 2.06-2.29 × 10(-6) cm(2) s(-1). It ranged between 1.10 and 2.03 × 10(-6) cm(2) s(-1) in the presence of fulvic acid and in natural waters with low DOM. In the presence of 20 ppm of humic acid of an organic-rich soil, plutonium diffusion was hindered by a factor of 5, with a diffusion coefficient of 0.50 × 10(-6) cm(2) s(-1). We also tested commercially available DGT devices with Chelex resin for plutonium bioavailability measurements in laboratory conditions and the diffusion coefficients agreed with those from the diffusion cell experiments. These findings show that the DGT methodology can be used to investigate the bioaccumulation of the labile plutonium fraction in aquatic biota.

Asterococcus superbus as a biosorbent of copper, zinc, cadmium and lead: adsorption isotherm and kinetic modelling

The adsorption capacity of copper, zinc, cadmium and lead by Asterococcus superbus, a freshwater microalgae, was studied in batch mode. The Langmuir, Freundlich, Temkin and Dubinin?Radushkevich models were applied and results demonstrate that for all cases the Langmuir model best describes the adsorption process and that A. superbus isotherm followed the bisorption series, Zn > Cu > Pb > Cd. Kinetic studies demonstrate that the adsorption of zinc and copper follows a pseudo-second-order kinetic model, and that of cadmium and lead follows a pseudo first-order kinetic model. Natural waters present an increasing concentration of heavy metals, mainly due to the effluent discharge in these type or reservoires. The importance of the present work is to contribute to the study of new methods to diminish the presence of heavy metals in natural waters.

Determination of heavy metals in natural water by the sorption-atomic-absorption method

The procedure for determining Hg, Cd, Pb, Zn, Cu elements in fresh water based on the preconcentration of these metals as complexes using poly-3-pyridyl-5-thioxo-4-allyl-4,5-dihydro-1H-1,2,3-triazole-1-carbodithionic acid with further measurement of atomic adsorption are proposed. The detection limits for metals are 5, 8, 20, 5 and 20 ng/dm3 respectively.

Optimization of dispersive liquid–liquid microextraction coupled with inductively coupled plasma -optical emission spectrometry with the aid of experimental design for simultaneous determination of heavy metals in natural waters

In this study, dispersive liquid–liquid microextraction (DLLME) combined with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed for simultaneous preconcentration and trace determination of chromium, copper, nickel and zinc in water samples. Sodium diethyldithiocarbamate (Na-DDTC), carbon tetrachloride and methanol were used as chelating agent, extraction solvent and disperser solvent, respectively. The effective parameters of DLLME such as volume of extraction and disperser solvents, pH, concentration of salt and concentration of the chelating agent were studied by a (2 f−1 ) fractional factorial design to identify the most important parameters and their interactions. The results showed that concentration of salt and volume of disperser solvent had no effect on the extraction efficiency. In the next step, central composite design was used to obtain optimum levels of effective parameters. The optimal conditions were: volume of extraction solvent, 113 μL; concentration of the chelating agent, 540 mg L −1; and pH, 6.70. The linear dynamic range for Cu, Ni and Zn was 1–1000 μg L −1 and for Cr was 1–750 μg L −1. The correlation coefficient ( R 2) was higher than 0.993. The limits of detection were 0.23–0.55 μg L −1. The relative standard deviations (RSDs, C = 200 μg L −1, n = 7) were in the range of 2.1–3.8%. The method was successfully applied to determination of Cr, Cu, Ni and Zn in the real water samples and satisfactory relative recoveries (90–99%) were achieved.