The potential risk assessment for different arsenic species in the aquatic environment

Arsenic and fluoride in groundwater triggering a high risk: Probabilistic results using Monte Carlo simulation and species sensitivity distribution

The widespread presence of arsenic (As) and fluoride (F-) in groundwater poses substantial risks to human health on a global scale. These elements have been identified as the most prevalent geogenic contaminants in groundwater in northern Mexico. Consequently, this study aimed to evaluate the human health and ecological risks associated with the content of As and F- in the Meoqui-Delicias aquifer, which is in one of Mexico's most emblematic irrigation districts. Concentrations of As and F- were measured in 38 groundwater samples using ICP-MS and ion chromatography, respectively. Overall, these elements showed a similar trend across the aquifer, revealing a positive correlation between them and pH. The concentration of As and F- in the groundwater ranged from 5.3 μg/L to 303 μg/L and from 0.5 mg/L to 8.8 mg/L, respectively. Additionally, the levels of As and F- surpassed the established national standards for safe drinking water in 92% and 97% of samples, respectively. Given that groundwater is used for both agricultural purposes and human activities, this study also assessed the associated human health and ecological risks posed by these elements using Monte Carlo simulation and Species Sensitivity Distribution. The findings disclosed a significant noncarcinogenic health risk associated with exposure to As and F-, as well as an unacceptable carcinogenic health risk to As through water consumption for both adults and children. Furthermore, a high ecological risk to aquatic species was identified for F- and high to medium risks for As in the sampling sites. Therefore, the findings in this study provide valuable information for Mexican authorities and international organizations (e.g., WHO) about the adverse effects that any exposure without treatment to groundwater from this region represents for human health.

Integration of environmental signatures and omics-based approaches on the European flounder to assist with health assessment of estuarine ecosystems in Brittany, France

This study aimed to develop a multidisciplinary approach to assess the ecological status of six moderate-sized French estuaries. For each estuary, we gathered geographical information, hydrobiological data, chemistry of pollutants and fish biology, including integration of proteomics and transcriptomics data. This integrative study covered the entire hydrological system studied, from the watershed to the estuary, and considered all the anthropogenic factors that can impact this environment. To reach this goal, European flounder (Platichthys flesus) were collected from six estuaries in September, which ensures a minimum residence time of five months within an estuary. Geographical metrics are used to characterize land use in each watershed. The concentrations of nitrite, nitrate, organic pollutants, and trace elements were measured in water, sediments and biota. All of these environmental parameters allowed to set up a typology of estuaries. Classical fish biomarkers, coupled with molecular data from transcriptomics and shotgun proteomics, highlighted the flounder's responses to stressors in its environment. We analysed the protein abundances and gene expression levels in the liver of fish from the different estuaries. We showed clear positive deregulation of proteins associated with xenobiotic detoxification in a system characterized by a large population density and industrial activity, as well as in a predominantly agricultural catchment area (mostly cultures of vegetables and pig breeding) mainly impacted by pesticides. Fish from the latter estuary also displayed strong deregulation of the urea cycle, most probably related to high nitrogen load. Proteomic and transcriptomic data also revealed a deregulation of proteins and genes related to the response to hypoxia, and a probable endocrine disruption in some estuaries. Coupling these data allowed the precise identification of the main stressors interacting within each hydrosystem.

The Relationship of Arsenic Exposure with Hypertension and Wide Pulse Pressure: Preliminary Evidence from Coal-Burning Arsenicosis Population in Southwest China

Evidence from epidemiological studies suggests that chronic arsenic exposure may be associated with a higher incidence of hypertension in the population. However, the effect of arsenic exposure on blood pressure remains unexplored in different populations, regions, and regarding arsenic biomarkers. This study investigated 233 arsenicosis patients and 84 participants from a non-arsenic-exposed area to explore the relationship between arsenic exposure and blood pressure and the occurrence of hypertension and wide pulse pressure (WPP) in patients with coal-burning arsenicosis. The results show that arsenic exposure is related to an increased incidence of hypertension and WPP in the arsenicosis population, primarily due to an induced increase in systolic blood pressure (SBP) and pulse pressure (PP) (OR = 1.47, 1.65, all p < 0.05). The dose-effect relationships between monomethylated arsenicals (MMA), trivalent arsenic (As³⁺), hypertension, and WWP were characterized following trend analyses (all p-trend < 0.05) in the coal-burning arsenicosis population. After adjusting for age, gender, body mass index (BMI), smoking, and alcohol usage, compared with low-level exposure, the high level of MMA exposure increases the risk of hypertension by 1.99 times (CI: 1.04-3.80) and the WPP by 2.42 times (CI: 1.23-4.72). Similarly, the high level of As³⁺ exposure increases the hypertension risk by 3.68 times (CI: 1.86-7.30) and the WPP by 3.84 times (CI: 1.93-7.64). Together, the results revealed that urinary MMA and As³⁺ levels are mainly associated with increased SBP and induce a higher incidence of hypertension and WPP. This study provides preliminary population evidence that cardiovascular-related adverse events such as hypertension and WPP ought to be noticed in the coal-burning arsenicosis population.

Occurrence, bioaccumulation and ecological risk of organic ultraviolet absorbers in multiple coastal and offshore coral communities of the South China Sea

The occurrence of organic ultraviolet absorbers (OUVAs) in coral reef regions has aroused widespread concern. This study focused on the occurrence, distribution, bioaccumulation and ecological risk of ten OUVAs in both coastal and offshore coral reef regions in the South China Sea. While the Σ₁₀OUVAs was 85 % lower in the offshore seawater (15.1 ng/L) than in the coastal seawater (102.1 ng/L), the Σ₁₀OUVAs was 21 % lower in the offshore corals (1.82 μg/g dry weight (dw)) than in the coastal corals (2.31 μg/g dw). This difference was speculated to relate to the high intensity of human activities in the coastal regions. Moreover, the offshore corals showed higher bioaccumulative capability toward OUVAs (log bioaccumulation factors (BAFs): 1.22-5.07) than the coastal corals (log BAFs: 0.17-4.38), which was presumably the influence of varied physiological status under different environmental conditions. The results of the ecological risk assessment showed that BP-3 resulted in 73 % of coastal corals and 20 % of offshore corals at a risk of bleaching. Therefore, the usage and discharge of BP-3 should be managed and controlled by the countries adjacent to the South China Sea for the protection of coral reefs.

The dynamic changes of arsenic biotransformation and bioaccumulation in muscle of freshwater food fish crucian carp during chronic dietborne exposure

Dietary uptake is the major way that inorganic arsenic (iAs) enters into benthic fish; however, the metabolic process of dietborne iAs in fish muscle following chronic exposure remains unclear. This was a 40-day study on chronic dietborne iAs [arsenite (AsIII) and arsenate (AsV)] exposure in the benthic freshwater food fish, the crucian carp (Carassius auratus), which determined the temporal profiles of iAs metabolism and toxicokinetics during exposure. We found that an adaptive response occurred in the fish body after iAs dietary exposure, which was associated with decreased As accumulation and increased As transformation into a non-toxic As form (arsenobetaine). The bioavailability of dietary AsIII was lower than that of AsV, probably because AsIII has a lower ability to pass through fish tissues. Dietary AsV exhibited a high potential for transformation into AsIII species, which then accumulated in fish muscle. The largely produced AsIII considered more toxic at the earlier stage of AsV exposure should attract sufficient attention to human exposure assessment. Therefore, the pristine As species and exposure duration had significant effects on As bioaccumulation and biotransformation in fish. The behavior determined for dietborne arsenic in food fish is crucial for not only arsenic ecotoxicology but also food safety.

Transfer and bioavailability of inorganic and organic arsenic in sediment-water-biota microcosm

Arsenic (As) contamination in the sediments has received increasing attention, but its transfer and bioavailability to benthic infauna remain much less well known. In the present study, we deployed the diffusive gradients in thin films (DGT) to quantify the different As speciation in the overlying water and porewater, and assessed the exposure pathway, transfer and bioavailability of different As species in an infaunal clam Sinonovacula constricta. We demonstrated a very dynamic transformation and exposure of As in the sediment-water-clam microcosm. In such microcosm, arsenite [As(III)] in the overlying water, pore water and sediments was almost oxidized to arsenate [As(V)]. Conversely, the accumulated As(V) in the clams was reduced to As(III), followed by methylation to dimethylarsinic acid (DMA), whereas the overall conversion of toxic inorganic As species to less-toxic arsenobetaine (AsB) was much poor in the clams. Moreover, biotransformation depended on the As accumulation level. As(III) was the predominant As species in the control and the Low As treatment clam, whereas DMA was the predominant As species in the High As treatment clam. Significant and positive correlations were found between As(V) concentrations in the clams and those in DGT-labile As in overlying water/pore water, as well as between the DMA and As(V) concentrations in the clams and those in the sediment. DMA and As(V) in the sediments was much more bioavailable to the clams than inorganic As [As(III)] and AsB. Moreover, As(III) and As(V) in the overlying water and pore water, as well as DMA and As(V) in the sediments displayed high migration ability. Coupled DGT technology and biotransformation study therefore suggested that metabolism of ingested As species as well as ingestion and retention of DMA resulted in high DMA bioaccumulation in clams.

New application of lanthanum-modified bentonite (Phoslock®) for immobilization of arsenic in sediments

Lanthanum-modified bentonite (LMB, Phoslock^®) is a well-known capping agent for phosphorus immobilization in sediments. Herein, LMB was used to immobilize As in sediments. Batch capacity experiments for arsenate and arsenite adsorption were carried out to obtain adsorption isotherms and kinetics using the Langmuir and Freundlich model calculations. High-resolution (HR) diffusive gradients in thin films (DGT) were applied to monitor the changes of weakly bound As fraction near sediment-water interface (SWI). The interaction of As(III) and As(V) with LMB was influenced by pH and initial mineral composition. As(V) was more obviously adsorbed than As(III) at pH 4 to 9, with mean adsorption of 3.89 mg g^-1 and 0.04 mg g^-1, respectively, while at pH > 9 As(III) was preferentially adsorbed. After LMB amendment for 2 months, the maximum As removal efficiency in the pore and overlying water reached 84.5% and 99.3%, respectively. The capping agent remained stable in the top sediments, while the maximum DGT labile As content decreased to 0.89 and 0.51 μg L^-1 in dosage-and time-treatments. The As concentration inflection point moved down to a deeper layer. As species changed from labile exchangeable-As to Fe-oxide-bound and residual As. The proportion of mobile As finally decreased to 10.5% of the total As in the upper 20-mm layer sediment. The increase of K_d (the distribution coefficient at SWI) and k₁ (adsorption rate constant) and the decrease of T_c (response time of (de)sorption) in the DGT-induced fluxes model (DIFS) indicated the time-dependent impediment of As release from the sediment due to LMB immobilization.

UV photochemical hydride generation using ZnO nanoparticles for arsenic speciation in waters, sediments, and soils samples

The environmental disasters that occurred due to the leakage of mining waste in Mariana-MG (2015) and Brumadinho-MG (2019), located in Brazil, attracted the attention of the scientific community. This designated efforts to investigate the environmental consequences of toxic waste in the affected ecosystem. Therefore, a simple, easily executed and accessible method was presented for arsenic speciation [As(III), As(V), and DMA]. Using an atomic absorption spectrometer coupled to the hydride generation system, the heterogeneous photocatalysis was applied in the reduction of As(V) and DMA to As(III). After the optimization, a calibration curve was constructed, with LODs equivalent to 3.20 μg L^-1 As(III), 3.86 μg L^-1 As(V), and 6.68 μg L^-1 DMA. When applying the method for quantification in environmental samples, a concentration of up to 103.1 ± 9.4 μg L^-1 As(V) was determined for surface water samples. The soil samples, 84.1 ± 3.6 μg L^-1 As(III) and 112.4 ± 9.9 μg L^-1 As(V) were quantified, proving the contamination of the ecosystems impacted by the environmental disasters. We proceeded the study through an addition/recovery method with samples of water, soil, and sediments (collected from impacted environments). Recovery values were equivalent to 99.0% for As(III), 93.8% for As(V), and 99.2% for DMA. Graphical abstract Photocatalytic reduction mechanism of As(V) and DMA to As(III) by heterogeneous photocatalysis.

Predicted no-effect concentrations determination and ecological risk assessment for benzophenone-type UV filters in aquatic environment

Benzophenones (BPs), a group of widely used ultraviolet filters, have been frequently detected out in multiple environment matrices even in organism bodies. Although a variety of toxicological effects of BPs have been disclosed recently, it is barely to evaluate the potential ecological risk of BPs due to lack of reference criteria. Therefore, the determination of predicted no-effect concentration (PNEC) values is necessary for assessing ecological risk of BPs and for protecting safety of aquatic organisms. The toxicological data of 14 BPs from both in vivo tests on aquatic organisms and in vitro tests on strains/cell lines were collected from previous reports, and two methods including assessment factor (AF) and species sensitivity distribution (SSD) were applied to calculate PNECs, respectively. Four groups of PNECs were obtained and compared, a final PNEC value was recommended for each BP based on reliable and conservative consideration. With these PNECs values, the risk quotients of 8 BPs from 35 ambient freshwater samples were calculated, the results demonstrated that 3 BPs including 2,2',4,4'-tetrahydroxyl-BP, 2-hydroxyl-4-methoxyl- BP, and 2-hydroxyl-4-methoxyl-5-sulfonic acid-BP exhibited high ecological risk, and the ecological risk posed by BPs in River Tiff in UK was great. It is anticipated that these results would provide useful reference for assessing and managing BP-type compounds, and for selecting toxicity data and methods to derive PNECs for emerging contaminants.

First observation of labile arsenic stratification in aluminum sulfate-amended sediments using high resolution Zr-oxide DGT

Arsenic contamination in sediments has received increasing attention because it may be released to the water and threaten aquatic organisms. In this study, aluminum sulfate (ALS) was used to immobilize As in sediments through dosage-series and time-series experiments. Diffusive gradients in thin films (DGT) was used to obtain labile As at a vertically 2.0mm resolution. Our results indicated that a "static" layer with extremely low labile As concentration (minimally 0.13mgL^-1) with weak variation (<30% RSD) formed within the top 12mm sediment layer at the dosage of 6-12ALS/As_mobile (kmolmol^-1, As_mobile means the total mobile As in top 40mm sediment) and on days 30-80 after amendment at the dosage of 9 ALS/As_mobile. The maximum labile As decreased from 1.83 to 0.99μgL^-1 and from 1.96 to 1.20μgL^-1 in the dosage-series (3-12 ALS/As_mobile) and time-series (10-80days) experiments, respectively, while the depths showing the maximal concentrations moved deeper from 22 to 34mm and 20 to 32mm in the sediments. It implied a reduced upward diffusion potential of labile As to the static layer in deeper sediments. Both distribution coefficient for As between sediment solid pool and pore water (K_d) and the adsorption rate constant (k₁) consistently increased, reflecting that As release from sediment solid became increasingly difficult with the progress of ALS immobilization. The results of this millimeter-scale investigation showed that ALS could efficiently immobilize As in sediments under simulated conditions.

Fe-FeS2 adsorbent prepared with iron powder and pyrite by facile ball milling and its application for arsenic removal

Arsenic is one of the major pollutants and a worldwide concern because of its toxicity and chronic effects on human health. An adsorbent of Fe-FeS2 mixture for effective arsenic removal was successfully prepared by mechanical ball milling. The products before and after arsenic adsorption were characterized with scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The adsorbent shows high arsenic removal efficiency when molar ratio of iron to pyrite is 5:5. The experimental data of As(III) adsorption are fitted well with the Langmuir isotherm model with a maximal adsorption capacity of 101.123 mg/g. And As(V) data were described perfectly by the Freundlich model with a maximal adsorption capacity of 58.341 L/mg. As(III) is partial oxidized to As(V) during the adsorption process. High arsenic uptake capability and cost-effectiveness of waste make it potentially attractive for arsenic removal.

Differential mechanistic investigation of protective effects from imperatorin and sec-O-glucosylhamaudol against arsenic trioxide-induced cytotoxicity in vitro

BACKGROUND AND PURPOSE

The clinical use of arsenic trioxide (As₂O₃) for treating acute promyelocytic leukemia (APL) is limited due to its severe cardiotoxicity. The possible mechanisms of As₂O₃-induced cardiotoxicity include DNA fragmentation, reactive oxygen species (ROS) generation, cardiac ion channel changes and apoptosis. The present study is designed to investigate the protective effects of imperatorin and sec-O-glucosylhamaudol and to explore their mechanistic involvement in As₂O₃-induced cytotoxicity.

EXPERIMENTAL METHODS

Cell viability assay, Lactate dehydrogenase (LDH) release, Acridine orange/ethidium bromide (AO/EB) double staining, Caspase-3 activity assay, ROS generation, cellular calcium levels, mRNA expression levels by qRT-PCR and protein expression levels by Western blotting were measured in H9c2 cells in combination with As₂O₃ and imperatorin or sec-O-glucosylhamaudol.

KEY RESULTS

We observed that H9c2 cells treated with imperatorin or sec-O-glucosylhamaudol were more resistant to As₂O₃-induced cell death. Both imperatorin and sec-O-glucosylhamaudol reduced H9c2 cell apoptosis, but both imperatorin and sec-O-glucosylhamaudol had no effects on Caspase-3 activity and intracellular calcium accumulation. Furthermore, imperatorin was capable of suppressing ROS generation, while sec-O-glucosylhamaudol did not show this effect. Moreover, imperatorin and sec-O-glucosylhamaudol triggered Nrf2 activation, which resulted in upregulation of downstream phase II metabolic enzymes and antioxidant protein/enzyme, probably offering cellular protection to As₂O₃-induced cardiotoxicity via the Nrf2 signal pathway.

CONCLUSIONS AND IMPLICATIONS

Imperatorin and sec-O-glucosylhamaudol can ameliorate As₂O₃-induced cytotoxicity and apoptosis in H9c2 cells, the mechanisms probably related to antioxidation. As₂O₃ in combination with imperatorin or sec-O-glucosylhamaudol could be considered as a novel strategy to expand the clinical application of As₂O₃.