A Simplified Model to Estimate the Concentration of Inorganic Ions and Heavy Metals in Rivers

Identification of sources and transport pathways of heavy metals and major ions is crucial for effective water quality monitoring, particularly in large river systems. The Ganges river basin, the largest and the most populous river basin in India, remains poorly studied in this regard. We conducted a basin-level analysis of major ions, heavy metals, and stable isotopes of nitrate in the Ganges during the pre-monsoon season to constrain the sources and quantify the inorganic chemical composition of the river during its lean flow. Bedrock weathering, anthropogenic interferences, water contribution through tributaries, and surface water-groundwater interaction were identified as the major driver of metal and ion variability in the river. Heavy metals showed the highest concentrations in the upper section of the river, whereas ionic loads were the most variable in the middle. We find a significant impact of tributaries on the metal and ion concentrations of the Ganges in its lower reaches. Isotopic analysis of dissolved nitrate suggested synthetic fertilizers and industrial wastes as the main sources. We find that the otherwise clean waters of the Ganges can show high ionic/metallic concentrations at isolated stretches (As: up to 36 µg/L), suggesting frequent monitoring in the source region to maintain water quality. Except for water collected from the Yamuna and Kannauj in the middle stretch and the Alaknanda and Rishikesh in the upper stretch, the WQI showed acceptable water quality for the sampled stations. These findings provide an insight into the modifications of dissolved inorganic chemical loads and their sources in different sections of the basin, needed for mitigating site-specific pollution in the river, and a roadmap for evaluating chemical loads in other rivers of the world.

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“…Similar to major ions, Station 18 behaved distinctly for heavy metals as well (Figure 3b). [34], and for heavy metals are after [35].…”

Section: Resultsmentioning

confidence: 99%

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Sharma

Liang

Laskar

et al. 2023

Water

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“…P removal capacity was tested in the presence of anions like chloride, bromide, iodide, nitrate, bicarbonate, and sulfate, which are commonly found in surface waters (Figure ). For instance, the concentration of some of these ions in the rivers located in North America are: Cl – 8 ppm, NO 3 – 1 ppm, HCO 3 – 68 ppm, and SO 4 2– 20 ppm . To test the effect of the interfering ions, concentrations of these anions in the 0–100 ppm range were mixed with 50 ppm of P solutions and then exposed to 5 mg of the MOF.…”

Section: Results and Discussionmentioning

confidence: 99%

“…For instance, the concentration of some of these ions in the rivers located in North America are: Cl − 8 ppm, NO 3 − 1 ppm, HCO 3 − 68 ppm, and SO 4 2− 20 ppm. 49 To test the effect of the interfering ions, concentrations of these anions in the 0−100 ppm range were mixed with 50 ppm of P solutions and then exposed to 5 mg of the MOF. The solutions were mixed for 1 h then filtered and tested for the remaining P level in the supernatant.…”

Section: Effect Of Interfering Ions and Phmentioning

confidence: 99%

Ultrafast Removal of Phosphate from Eutrophic Waters Using a Cerium-Based Metal–Organic Framework

Hassan

Stanton

Secora

et al. 2020

ACS Appl. Mater. Interfaces

110

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Phosphate removal has become a critical need to mitigate the negative effect of water eutrophication, which is responsible for the overgrowth of toxic algal blooms and the significant ecological harm generated to aquatic ecosystems. However, some of the currently available adsorbents have low removal capacity and function optimally at specific pH ranges. Here, we present an example of a cerium-based metal–organic framework (MOF) as a high-capacity sorbent for phosphate removal from eutrophic waters. Specifically, a Ce(IV)-based UiO-66 analogue, Ce 1,4-benzenedicarboxylate (Ce-BDC), was selected due to its water stability, high surface area, microporous structure, and the high binding affinity of phosphate with its open metal sites. Mechanistic studies supported by density functional theory (DFT) calculations indicate the formation of a Ce–O–P bond through ion exchange between the terminal (nonbridging) hydroxyl groups at the missing linker sites and the phosphate adducts. Experimental results demonstrate that Ce-BDC is highly selective for phosphates over other common anions (Cl–, Br–, I–, NO3 –, HCO3 –, SO4 2–) and stable in a broad pH range of (2–12), covering the relevant range for the treatment of contaminants in aquatic systems. The sorbent shows a fast removal rate, capturing significant amounts of phosphate within 4 min with a maximum adsorption capacity of 179 mg·g–1, outperforming other porous materials. These results show a remarkable adsorption capacity and fast kinetics compared with the current state-of-the-art crystalline porous materials. This study may advance the design of new microporous materials with high adsorption capabilities, good stability, and make a significant contribution to the development of future generation technology to mitigate the negative effects of water eutrophication.

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“…Concentrations (M) of anions higher than those present in natural water were used in this study to ensure that there were anionic interferences (see Table 1). Inorganic anions generally exist in natural water in the range of µM-mM [23][24][25], and concentrations of organic anions are present in the nM-µM range [25][26][27][28][29].…”

Section: Washing Efficiency Of Deionized Water On Interferences From ...mentioning

confidence: 99%

A Simplified Method for Anionic Surfactant Analysis in Water Using a New Solvent

Yoon

Shin²,

Kirkham

et al. 2022

Toxics

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Anionic surfactants (AS) are becoming a major emerging contaminant of waters due to their widespread use in household and industrial products. The standard chloroform method for analysis of AS in water relies on chloroform extraction of a methylene blue active substance (MBAS), which contains ion pairs between methylene blue (MB) molecules (positively charged) and AS. Due to the poor extractability of chloroform, the procedure is complicated, time-consuming, and subject to anionic interferences. A mixture of methyl isobutyl ketone (MIBK)–1,2-dichloroethane (DCE) at a 3:1 ratio of MIBK:DCE proved to be a robust solvent for AS extraction for a wide range of samples under various chemical conditions. The objectives of this research were to set the washing protocol to eliminate the anionic interferences in the MIBK-DCE extraction and to develop a new simplified analytical method for AS analysis using the MIBK-DCE (3:1) extractant. The suitability of the proposed MIBK-DCE method was validated based on quality control and assurance criteria, such as selectivity, accuracy, precision, method detection limit (MDL), limit of quantification (LOQ), and sensitivity. Various water samples, such as freshwater, wastewater, and seawater, were used for the method development and validation. Interferences by inorganic and organic anions were evident in the reference chloroform method but were eliminated in the MIBK-DCE procedure with a two-step process that consisted of washing with a carbonate/bicarbonate solution at pH 9.2 and a mixture of silver sulfate (Ag2SO4) and potassium alum (AlK(SO4)2). The simplified MIBK-DCE method for sodium dodecyl sulfate (SDS) analysis consisted of (i) sample pre-treatment, (ii) MIBK-DCE extraction, (iii) washing and filtration, and (iv) absorbance measurement. The MIBK-DCE method was accurate, precise, selective, and sensitive for AS analysis and showed MDL of 0.0001 mg/L, LOQ of 0.0005 mg/L, relative standard deviation (RSD) of 0.1%, and recovery of 99.0%. All these criteria were superior to those of the chloroform method. Sensitivity analysis showed highly significant correlations in AS analyses between the MIBK-DCE and chloroform methods for domestic wastewater, industrial wastewater, and seawater. The MIBK-DCE method is simple, rapid, robust, reproducible, and convenient, when compared to the chloroform method. Results demonstrate that the simplified MIBK-DCE method can be employed for AS analysis in a wide range of environmental waters including seawater.

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A Simplified Model to Estimate the Concentration of Inorganic Ions and Heavy Metals in Rivers

Cited by 7 publications

References 12 publications

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Basin-Scale Geochemical Assessment of Water Quality in the Ganges River during the Dry Season

Ultrafast Removal of Phosphate from Eutrophic Waters Using a Cerium-Based Metal–Organic Framework

A Simplified Method for Anionic Surfactant Analysis in Water Using a New Solvent

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