The speciation of inorganic arsenic in soil and vegetables irrigated with treated municipal wastewater

Impacts of continuous irrigation using treated municipal wastewater on rice-soil systems: A three-year study

Research on the effects of rice fertigation using treated municipal wastewater (TWW) as the sole source of nutrients and irrigation water remains limited. This study examined the impact of continuous TWW irrigation on rice-soil systems across three years (2021-2023), focusing on soil health, plant growth and yield, and the mineral and toxic element composition of rice grains. Forage rice cultivation using TWW fertigation (test field) was compared with conventional cultivation using chemical fertilisers and canal water (control field). The test field exhibited an average total nitrogen (TN) removal rate of 72 % across three crop seasons. However, low TN concentrations in TWW (2021: 4.7 mg L-1, 2022: 9.9 mg L-1, 2023: 2.8 mg L-1) resulted in lower leaf greenness, plant height, and shoot biomass compared to the control, particularly in 2023 (p < 0.01). In the same year, rice protein content in the test field (5.9 %) was significantly lower than the control (6.5 %) (p < 0.001), while mineral compositions remained consistent across fields (p > 0.05). Significant increases in K, Mg, Na, and Zn concentrations were observed in rice grains from the test field in 2021 (p < 0.05). However, As levels in the test field grains (0.35 mg kg-1) in 2023 approached the maximum allowable limit and were significantly higher than that in the control (0.25 mg kg-1), raising food safety concerns. TWW irrigation maintained soil C levels, with the test field exhibiting higher C:N ratios, humification indices, and complex carbon structures (RET:Bz and SUVA254) across the three seasons. These improvements enhanced soil structure and nutrient retention. While TWW irrigation shows potential as sustainable alternative to chemical fertilisers, optimizing its application to address varying N concentrations and complex organic matter dynamics is essential to maximize productivity and ensure food safety and environmental sustainability.

A review on arsenic contamination in drinking water: sources, health impacts, and remediation approaches

Arsenic (As) contamination in groundwater has become a global concern, and it poses a serious threat to the health of millions of people. Groundwater with high As concentrations has been reported worldwide. It is widely recognized that the toxicity of As largely depends on its chemical forms, making As speciation a critical issue. Numerous studies on As speciation have been conducted, extending beyond the general knowledge on As to the toxicity and health issues caused by exposure to various As species in water. This article reviews various As species, their sources and health effects, and treatment methods for the removal of As from contaminated water. Additionally, various established and emerging technologies for the removal of As contaminants from the environment, including adsorption (using rocks, soils, minerals, industrial by-products, biosorbents, biochars, and microalgal and fungal biomass), ion exchange, phytoremediation, chemical precipitation, electrocoagulation, and membrane technologies, are discussed. Treating As-contaminated drinking water is considered the most effective approach to minimize the associated health risks. Finally, the advantages and disadvantages of various remediation and removal methods are outlined, along with their key advantages. Among these techniques, the simplicity, low cost, and ease of operation make adsorption techniques desirable, particularly with the use of novel functional materials like graphite oxides, metal-organic frameworks, carbon nanotubes, and other emerging functional materials, which are promising future alternatives for As removal.

Deep Eutectic Solvents for Extraction and Preconcentration of Organic and Inorganic Species in Water and Food Samples: A Review

Deep eutectic solvents (DESs) have been developed as green solvents and these are capable as alternatives to conventional solvents used for the extraction of organic and inorganic species from food and water samples. The continuous generation of contaminated waste and increasing concern for the human health and environment have compelled the scientific community to investigate more ecological schemes. In this concern, the use of DESs have developed in one of the chief approach in the field of chemistry. These solvents have appeared as a capable substitute to conventional hazardous solvents and ionic liquids. The DESs has distinctive properties, easy preparation and components availability. It is not only used in scienctific fields but also used in quotidian life. There are many advantages of DESs in analytical chemistry, they are largely used for extraction and determination of inorganic and organic compounds from different samples. In previous a few years, several advanced researches have been focused on the separation and preconcentration of low level of pollutants using DESs as the extractants. This review summarizes the use of DESs in the separation and preconcentration of organic and inorganic species from water and food samples using various microextraction processes.

Recent developments in speciation and determination of arsenic in marine organisms using different analytical techniques. A review

Marine organisms play a vital role as the main providers of essential and functional food. Yet they also constitute the primary pathway through which humans are exposed to total arsenic (As) in their diets. Since it is well known that the toxicity of this metalloid ultimately depends on its chemical forms, speciation in As is an important issue. Most relevant articles about arsenic speciation have been investigated. This extended not only from general knowledge about As but also the toxicity and health related issues resulting from exposure to these As species from the food ecosystem. There can be enormous side effects originating from exposure to As species that must be measured quantitatively. Therefore, various convenient approaches have been developed to identify different species of As in marine samples. Different extraction strategies have been utilized based on the As species of interest including water, methanol and mixtures of both, and many other extraction agents have been explained in this article. Furthermore, details of hyphenated techniques which are available for detecting these As species have been documented, especially the most versatile and applied technique including inductively coupled plasma mass spectrometry.

Acid-based deep eutectic solvents followed by GFAAS for the speciation of As(III), As(V), total inorganic arsenic and total arsenic in rice samples

In the present study, an efficacious, safe, inexpensive and eco-friendly microextraction was provided by deep eutectic solvents based on dispersive liquid-liquid microextraction (DLLME - DES) followed by GFAAS. A series of DESs were synthesised using l-menthol as hydrogen bond acceptor (HBA) and carboxylic acids with 4, 6, 8 and 10 carbon atoms as hydrogen bond donors (HBD). The synthesised DESs were used as extractants of arsenic ions. Under optimised conditions, good linearity with coefficient of determination (r2) 0.992 and an acceptable linear range of 0.3-100 µg kg-1 was obtained. The limit of detection was 0.1 µg kg-1 (S/N = 3) for arsenite (As(III)) ions, and a high enrichment factor (EF = 200) was obtained. The enhancement factor and extraction recovery (ER%) of the method were 340 and 60%, respectively. RSDs including inter- and intra-day ranged from 3.2% to 5.8% in three examined concentrations. After a specific digestion, the capability of the synthesised DES in the extraction of As(III) from rice was tested. Total inorganic arsenic was separated similarly after reduction of arsenate (As(V)) to As(III), and As(V) concentration was calculated by difference. Using a second digestion method, total arsenic concentration (sum of organic and inorganic arsenic) in the samples was determined.

Toxicity, arsenic speciation and characteristics of hyphenated techniques used for arsenic determination in vegetables. A review

Arsenic (As) speciation is an interesting topic because it is well recognized that the toxicity of this metalloid ultimately depends on its chemical form. More than 300 arsenicals exist naturally. However, As can be present in four oxidation states: As-III, As0, AsIII and AsV. Long-term exposure to As from different sources, such as anthropogenic processes, or water, fauna and flora contaminated with As, has put human health at risk for decades. There are many side-effects correlated with exposure to InAs species, such as skin problems, respiratory diseases, kidney problems, cardiovascular diseases and even cancer. There are different levels and types of As in foods, particularly in vegetables. Furthermore, different chemical methods and techniques have been developed. Therefore, this review focuses on the general properties of various approaches used to identify As species in vegetation samples published worldwide. This includes various approaches (different solvents and techniques) used to extract As species from the matrix. Then, versatile chromatographic and non-chromatographic systems to separate different forms of As are reviewed. Finally, the general properties of the most common instruments used to detect As species from samples of interest are listed.

Extraction and determination of aflatoxin B1 in cereal samples using pH-switchable hydrophobic deep eutectic solvents followed by HPLC-FL analysis

A quick, simple and environmentally friendly liquid phase microextraction (LPME) sample pretreatment procedure was proposed based on pH-switchable hydrophobic deep eutectic solvents (HDESs) and high performance liquid chromatography coupled with a fluorescence detector (HPLC-FL). This method was used for the quantitative study of aflatoxin B1 (AFB1) and applied to eight widely consumed cereal samples. In this method, six different DESs were synthesized and then their pH-switchability was investigated. DESs that could be switched with pH were employed for separation and preconcentration of AFB1 in cereal samples. In this method, dispersing the extractant phase in the aqueous solution and subsequent phase separation are performed only by changing the pH. Important parameters affecting extraction, such as the type of DES and its volume, concentration of KOH, volume of HCL, effect of salt and extraction time were investigated and optimum conditions were obtained. Under the optimum conditions, relative standard deviation (RSD) values for intra-day and inter-day of the method based on seven replicate measurements of 5.0 μg kg-1 of AFB1 in cereal samples were 3.3 and 5.2%, respectively. The calibration graphs were linear in the range of 0.007-20 μg kg-1 and limit of detection (LOD) was 0.002 μg kg-1. The relative recoveries of real cereal samples which have been spiked with different levels of AFB1 were 90.8-107.5%.

Novel hydrophobic deep eutectic solvent for vortex-assisted liquid phase microextraction of common acaricides in fruit juice followed by HPLC-UV determination

In the present research, several novel and natural hydrophobic deep eutectic solvents (DESs) were prepared using methyltrioctylammonium chloride (MTOAC) as the hydrogen bond acceptor (HBA) and different types of straight chain alcohols as hydrogen bond donors (HBDs). One of the DESs composed of MTOAC and n-butanol was advantageously used to develop a vortex-assisted liquid phase microextraction (VALPME) method combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) for the determination of common acaricides in fruit juice samples. Several important parameters influencing extraction efficiency were investigated and optimized, including the type and volume of DES, sample solution pH, effect of salt addition and, extraction and vortex time. Under optimal experimental conditions, the method showed good linearity with the correlation coefficients (R 2) of 0.9986-0.9991 in the linear range of 2-300 μg L-1, low limits of detection of 0.5-1 μg L-1 and acceptable extraction recoveries in the range of 85-93%. The proposed method was successfully applied for the extraction and preconcentration of trace acaricides in real fruit juice samples, and the results demonstrated the potential of the synthesized DESs for the extraction and determination of contaminants in aqueous samples.

Preparation of environmental samples for chemical speciation of metal/metalloids: A review of extraction techniques

Chemical speciation is a relevant topic in environmental chemistry since the (eco)toxicity, bio (geo)chemical cycles, and mobility of a given element depend on its chemical forms (oxidation state, organic ligands, etc.). Maintaining the chemical stability of the species and avoiding equilibrium disruptions during the sample treatment is one of the biggest challenges in chemical speciation, especially in environmental matrices where the level of concomitants/interferents is normally high. To achieve this task, strategies based on chemical properties of the species can be carried out and pre-concentration techniques are often needed due to the low concentration ranges of many species (μg L^-1 - ng L^-1). Due to the significance of the topic and the lack of reviews dealing with sample preparation of metal (loid)s (usually, sample preparation reviews focus on the total metal content), this work is presented. This review gives an up-to-date overview of the most common sample preparation techniques for environmental samples (water, soil, and sediments), with a focus on speciation of metal/metalloids and determination by spectrometric techniques. Description of the methods is given, and the most recent applications (last 10 years) are presented.