Arsenic speciation in water, suspended particles, and coastal organisms from the Taehwa River Estuary of South Korea

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.

Arsenic distribution and partitioning in multiple media in a typical catchment in the Qinghai-Tibetan plateau: A comparison between freshwater and saltwater lakes

Arsenic (As) has been widely detected in surface media on the Qinghai-Tibetan Plateau (QTP); however, the differences in the As distribution and partitioning characteristics between freshwater and saltwater lakes remain poorly understood. To determine the distribution and partitioning characteristics of As, multimedia environmental samples were collected from a typical small watershed consisting of a river, wetland, and both freshwater and saltwater lakes on the QTP. Results showed that freshwater systems, represented by Hurleg Lake, were high in particulate arsenic (PAs) and low in dissolved arsenic (DAs), whereas the saltwater system represented by Tosen Lake, exhibited the reverse distribution. This discrepancy in As distribution was primarily attributed to evaporation enrichment, competitive adsorption of HCO3- and pH variations, as suggested by correlation analysis and stable isotopic composition of water. In the stratified Tosen Lake, an increasing trend of DAs in the water column was observed, potentially driven by the reductive dissolution of Fe (hydr)oxides and bacterial sulfate reduction in the anoxic bottom hypolimnion. Conversely, Hurleg Lake maintained oxic conditions with stable DAs concentrations. Notably, PAs was elevated in the bottom layer of both lakes, possibly due to uptake/adsorption by biogenic particles, as indicated by high levels of chl.α and suspended particulate matter. These findings offer insights into the potential future impact of climate change on As mobilization/redistribution in arid plateau lakes, with implications for management policies that regulate As pollution.

Toxic metal and metalloid contamination in seafood from an eutrophic Brazilian estuary and associated public health risks

Guanabara Bay (GB) is a highly contaminated estuarine system and an important fishing area in Southeastern Brazil. In this regard, knowledge concerning the association of certain contaminants in seafood to abiotic factors and human health risk assessments is still understudied. Therefore, this study aimed to quantify nine toxic elements in highly consumed crabs, shrimp, and squid, and associate the results with abiotic factors. A human health risk assessment was also performed. Our findings indicate that crabs are the main bioaccumulators. Transparency and depth were noteworthy for all three taxonomic groups. In general, contaminant concentrations were below the limits established by different international agencies, except for As, which was higher than the Brazilian limit (1 mg kg^-1). However, the Hazard Index identified risks to consumer health for the ingestion of seafood. This study emphasizes the importance of jointly evaluating different toxic elements, for a more accurate health risk assessment.

Effects of dams on As and Hg concentrations in three southeastern Brazil fluvial systems: Ocean inputs, sources and seasonal dynamics among environmental compartments

Damming rivers for hydropower generation interferes in the flow of water bodies and, consequently, in trace element biogeochemistry and transport. This study focused on the effects of dams on the seasonal dynamics of arsenic (As) and mercury (Hg) in three fluvial systems (Itabapoana River, Flechas Channel and Paraíba do Sul River) and on the input of these elements to the ocean. The elements were evaluated in suspended particulate matter (SPM), surface sediments, and the roots of the aquatic macrophyte Eichhornia crassipes. Our results showed that the proximity of the dams in the Flechas Channel and Rio Itabapoana in relation to their mouth (distances of 4 km and 58 km, respectively) changed As and Hg seasonal dynamics in the environmental compartments analyzed, with the Flechas Channel being the most impacted area. In contrast, the lower part of the Paraíba do Sul River that has more distant dams to its mouth (distance of 184 km) did not show such marked changes, suggesting that most of the inputs are coming from the long river reach. The isotopic and elemental composition of organic matter indicated the soils of native forests as the main source of trace elements to the water bodies. Flow rate was the main driver controlling As and Hg ocean inputs, with higher inputs observed in the Paraíba do Sul River (9.69 and 0.59 t∙year^-1, respectively) compared to the other assessed fluvial systems. Also, this study demonstrated that, if a dam is closer to the mouth of a river, less contaminants will be input.

Baseline titanium levels of three highly consumed invertebrates from an eutrophic estuary in southeastern Brazil

Titanium (Ti) is considered a contaminant of emerging interest, as it displays toxic potential and has been increasingly employed in everyday products, pharmaceuticals, and food additives, mainly in nanoparticle form. However, several knowledge gaps are still noted, especially concerning its dynamics in the water. In this context, this study aimed to quantify total Ti concentrations in highly consumed swimming crabs, squid, and shrimp from an important estuary located in southeastern Brazil. Ti concentrations were higher than those reported in most studies carried out worldwide. Animal length and weight, as well as, depth, transparency, dissolved oxygen, and salinity, significantly influence Ti concentrations in the animals. Human health risks were also noted after calculating a simulated exposure to titanium dioxide, especially considering the uncertainties regarding the effects of this element and the absence of regulatory limits.

Bioaccumulation of arsenic and immunotoxic effect in white shrimp (Penaeus vannamei) exposed to trivalent arsenic

Trivalent arsenic (As (III)) contamination in the marine environment can produce adverse effects in crustaceans. The present study investigated the chronic toxicity of As (III) in white shrimp (Penaeus vannamei) by analyzing the tissue bioaccumulation and non-specific immune responses. Shrimps were exposed to 0 (control), 50, 500, and 2500 μg/L of As (III) for 21 days. The results showed that the hepatopancreas was the main tissue of arsenic accumulation in white shrimp. The cumulative concentration of total arsenic and inorganic arsenic but not arsenobetaine was positively correlated with the exposure concentration. In vitro As (III) treatment (0-2500 μg/L) with haemocytes isolated from healthy shrimp did not cause the cytotoxicity, but this arsenic treatments inhibited the phagocytic rate and O₂^- production. Moreover, the decrease of total haemocyte count and the inhibition of phagocytic rate, phagocytic index, O₂^- production and phenoloxidase activity were observed in white shrimp under the exposure of As (III) over a period of 21 days. This study revealed that chronic As (III) stress could disturb arsenic metabolism and immune responses in P. vannamei.

A Systematic Review on Metal Dynamics and Marine Toxicity Risk Assessment Using Crustaceans as Bioindicators

Metals, many of which are potentially toxic, are present in the aquatic environment originated from both natural and anthropogenic sources. In these ecosystems, these elements are mostly deposited in the sediment, followed by water dissolution, potentially contaminating resident biota. Among several aquatic animals, crustaceans are considered excellent bioindicators, as they live in close contact with contaminated sediment. The accumulation of metal, whether they are classified as essential, when in excessive quantities or nonessential, not only cause damage to the health of these animals, but also to the man who consumes seafood. Among the main toxic elements to animal and human health are aluminum, arsenic, cadmium, chromium, copper, lead, mercury, nickel and silver. In this context, this systematic review aimed to investigate the dynamics of these metals in water, the main bioaccumulative tissues in crustaceans, the effects of these contaminants on animal and human health, and the regulatory limits for these metals worldwide. A total of 91 articles were selected for this review, and an additional 68 articles not found in the three assessed databases were considered essential and included, totaling 159 articles published between 2010 and 2020. Our results indicate that both chemical speciation and abiotic factors such as pH, oxygen and salinity in aquatic environments affect element bioavailability, dynamics, and toxicity. Among crustaceans, crabs are considered the main bioindicator biological system, with the hepatopancreas appearing as the main bioaccumulator organ. Studies indicate that exposure to these elements may result in nervous, respiratory, and reproductive system effects in both animals and humans. Finally, many studies indicate that the concentrations of these elements in crustaceans intended for human consumption exceed limits established by international organizations, both with regard to seafood metal contents and well as daily, weekly, or monthly intake limits set for humans, indicating consumer health risks.

Behaviour and distribution of arsenic in seawater and suspended particulate matter in the adjacent area of the Changjiang Estuary during summer and autumn

Water and suspended particulate matter (SPM) were collected from the Changjiang Estuary and its adjacent areas during summer (July) and autumn (October) to study the distributions and partitioning of arsenic. The dissolved arsenic (DAs) and particulate arsenic (PAs) concentration distributions were strongly affected by inputs from riverine discharge and water masses in the East China Sea, generally exhibiting a decreasing trend from inshore to offshore. The DAs concentration was higher in the surface water due to the influence of seawater stratification in summer, but it was not obvious in autumn. DAs and PAs concentrations in the estuary were significantly higher in autumn than in summer. Seasonal variations in arsenic were due to seasonal differences in riverine input (mainly the Changjiang River) and the intrusion of water masses. PAs showed a positive correlation with both SPM and turbidity. The highest PAs concentration was observed in the northern Changjiang Estuary affected by the YSCC, with higher turbidity during autumn. The higher concentration of PAs in autumn was affected by the high SPM input and resuspension of sediment. The water-particulate distribution coefficient of As in summer showed an increasing tendency with salinity, which might be caused by the decrease in the diameter of suspended particles in the open sea.

Arsenic speciation in fish from Baltic Sea close to chemical munitions dumpsites

Chemical weapons that were dumped in seas and oceans after World War II, including the Baltic Sea, are sources of pollution of marine areas. Sunken containers can corrode, unseal, and numerous compounds pass into the environment, including toxic forms of arsenic, which are then taken up by marine animals. This study aims to quantify concentration of total arsenic, inorganic arsenic (III + V), and organic compounds arsenobetaine, monomethylarsonic acid, dimethylarsinic acid in the muscle tissues of cod, herring, sprat, and flounder and the associated risk to consumer health. Sprat muscle (0.636 mg kg^-1) had the highest content of total arsenic, significantly less was noted in the muscles of herring (0.460 mg kg^-1) and flounder (0.588 mg kg^-1), and the least was in cod (0.390 mg kg^-1). Toxic inorganic arsenic compounds were present in the fish tested at levels below 0.02 mgkg^-1 and constituted from 3.45 to 5.75% of total arsenic. Arsenobetaine dominated among organic forms, and concentrations of it, like total arsenic, varied depending on the fish species. Consumer health risk was determined with the estimated daily intake, the target hazard quotient, and the carcinogenic risk. Estimated daily intake values for inorganic arsenic in herring, cod, sprat, and flounder were below the reference dose at 0.51 × 10^-5 mg kg^-1 b. w. day. The target hazard quotient factor of 0.0017 indicated there was no threat. Carcinogenic risk values were within the permissible range of 10^-6 to 10^-4. Current data indicate that inorganic arsenic compounds pose no risk to the health of consumers of Baltic fishes.

Monitoring and risk assessment of arsenic species and metals in the Taehwa River in Ulsan, the largest industrial city in South Korea

Toxic metals, As, and As species were monitored at 18 stations along the Taehwa River in Ulsan. The concentrations of Ni (98.4 μg/L) at stations near industrial areas were relatively high and exceeded the WHO's drinking water guidelines (70 μg/L) and the US EPA's national recommended water quality criteria (52 μg/L). Principal component analysis and cluster analysis revealed that Ni and Cu were more strongly influenced by industrial activity than other elements in the Taehwa River estuary. Analysis of the hazard quotient (HQ) and cancer risk (CR) indicated that As was of the greatest non-carcinogenic and carcinogenic concern. Notably, the HQ and CR of As^III at suburban stations exceeded 1 and 10^-4, respectively, representing a significant health risk. These results indicate that As speciation testing is crucial for the development of effective management plans based on health risks because the toxicity and mobility of As depend on its chemical form.

The potential of arsenic biomagnification in marine ecosystems: A systematic investigation in Daya Bay in China

In this study, we systematically investigated the bioaccumulation and trophic transfer of arsenic (As) in a typical semi-enclosed gulf, Daya Bay. Ten categories of organisms and environmental samples for As, δ¹³C, and δ¹⁵N analyses were collected from 14 sampling sites in all four seasons. The results demonstrated that As concentrations in the organisms and environmental samples were within the normal range of As levels in other uncontaminated marine ecosystems. Arsenic concentrations were generally lower in the pelagic organisms than in the benthic organisms. Arsenic concentrations in the organisms at higher trophic levels (fish, crabs, shrimp, and cephalopods) were lower in summer and higher in winter, while As in the environments was stable in all seasons. The results of δ¹³C and δ¹⁵N analysis indicated that this ecosystem had a marine-derived food web with approximately 3.5 trophic levels. The positive correlation of As and δ¹⁵N in the organisms demonstrated that As was biomagnified along trophic transfer in the whole gulf food web in winter and spring. Specifically, As was biomagnified in the benthic food chains in all four seasons and in the pelagic food chains in winter and spring. These trends were consistent with the analysis of As transfer among the categories within the empirical food web. The trophic magnification factors (TMFs) of As were generally higher among the benthic categories than the pelagic categories. In addition, As transfer from stomach content to muscle was positively correlated to δ¹³C in fish, suggesting that As transfer was enhanced by a benthic habit. These results demonstrated that As could be biomagnified in marine food webs for specific organism compositions and seasonal variations, and a benthic habit was an important promoter for As biomagnification. Therefore, this study partially explained previous investigations in which As trophic transfers were diverse among marine ecosystems.

16S rRNA Gene Amplicon Sequencing of Contaminated Coastal Sediment Collected from the Taehwa River Estuary, South Korea

The Taehwa River Estuary is one of the largest enclosed bays in east Korea. In order to understand the environment of the Taehwa River Estuary, the microbial diversity in the sediment of the estuary was investigated through 16S rRNA gene sequencing. The predominant phyla were Proteobacteria and Bacteroidetes in all locations.

The Taehwa River Estuary is one of the largest enclosed bays in east Korea. In order to understand the environment of the Taehwa River Estuary, the microbial diversity in the sediment of the estuary was investigated through 16S rRNA gene sequencing. The predominant phyla in all locations were Proteobacteria and Bacteroidetes.

Distribution and Geochemical Processes of Arsenic in Lake Qinghai Basin, China

Lake Qinghai in the Qinghai-Tibet plateau is the largest lake in China, but the geochemical understanding of arsenic (As) in the lake is lacking. Water, sediment, and soil samples were collected from Lake Qinghai, rivers flowing into the lake, and lands around the lake. Water samples were analyzed for major ions and As, while sediment and soil samples were analyzed for major elements and As. The average As concentration (25.55 μg L−1) in the lake water was significantly higher than that (1.39 μg L−1) in the river water (p < 0.05), due to the evaporative concentration of lake water. The average As concentration (107.8 μg L−1) in the pore water was significantly higher than that in the lake water, due to its secondary release from sediment solid phases in the reductive condition. The average As/Cl−, As/SO42− and As/Na molar ratios in the lake water were significantly lower than that in the river water, indicating As was partially transferred from dissolved phase to solid phase in the evaporative concentration process of the lake water. The average As/Ca molar ratio in the lake water was significantly higher than that in the river water, indicating more Ca than As precipitated in the lake water. Furthermore, the average As/Ca molar ratio in the lake water was significantly lower than that in the pore water, indicating more As than Ca was secondarily released from sediment solid phases. The average concentration of As(III) and As(V) were 0.35 and 1.04 μg L−1 for the river water, respectively, and 6.99 and 18.56 μg L−1 for the lake water, indicating As(V) was the predominant As form. The average As concentration was 16.75 mg kg−1 for the lake sediment and 13.14 mg kg−1 for the soil around the lake. Arsenic concentration was significantly negatively correlated with S and Ca concentration in the lake sediments, due to solid dilution effect induced by carbonate and sulfate precipitation. The average As/Sc molar ratio in the sediment (2.06) was significantly higher than that in the soil (1.32), indicating that relatively more As was enriched in the lake sediment.

An improved rapid analytical method for the arsenic speciation analysis of marine environmental samples using high-performance liquid chromatography/inductively coupled plasma mass spectrometry

Arsenic contamination in marine environments is a serious issue because some arsenicals are very toxic, increasing the health risks associated with the consumption of marine products. This study describes the development of an improved rapid method for the quantification of arsenic species, including arsenite (As^III), arsenate (As^V), arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), and monomethyl arsonic acid (MMA), in seaweed, sediment, and seawater samples using high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). ICP-MS based on dynamic reaction cells was used to eliminate spectral interference. Ammonium nitrate- and phosphate-based eluents were used as the mobile phases for HPLC analysis, leading to shorter overall retention time (6 min) and improved peak separation. Arsenicals were extracted with a 1% HNO₃ solution that required no clean-up process and exhibited reasonable sensitivity and peak resolution. The optimized method was verified by applying it to hijiki seaweed certified reference material (CRM, NMIJ 7405-a) and to spiked blank samples of sediment and seawater. The proposed method measured the concentration of As^V in the CRM as 9.6 ± 0.6 μg/kg dry weight (dw), which is close to the certified concentration (10.1 ± 0.5 μg/kg dw). The recovery of the six arsenicals was 87-113% for the sediment and 99-101% for the seawater. In the analysis of real samples, As^V was the most abundant arsenical in hijiki and gulfweed, whereas AsB was dominant in other seaweed species. The two inorganic arsenicals (As^III and As^V) and As^V were the most dominant in the sediment and seawater samples, respectively.

Speciation transformation of arsenic in abalone viscera hydrolysate fraction: In vitro digestion and in vivo metabolism

Speciation transformation of arsenic in the abalone viscera hydrolysate fraction (AVHF) was evaluated using in vitro and in vivo methods to determine its safety given that AVHF is rich in arsenic. The dimethylarsinic acid (DMA) proportion and some free amino acid contents increased, whereas arsenobetaine (AB) proportion decreased when AVHF was digested by pepsin. However, molecular weight distribution was unchanged, and no obvious changes were found in the intestinal medium. In the single-dose experiment, the AB concentration on the mouse plasma rapidly increased, which reached up to 12.53 ng/mL in 2 h after the administration of AVHF (10 g/kg body weight) and reduced to half of the maximum at 8 h after administration. Furthermore, alanine (Ala) content in the urine of mice increased at 8 h after AVHF administration, suggesting that Ala might be chelated with arsenic and could not be absorbed well. Long-term experiments showed that AB was not accumulated in mice tissue/organ. However, some AB could be converted into DMA, which was mainly accumulated in mice hair. The in vivo experiments also suggested that the AVHF is safe as health food.

Arsenic speciation in environmental multimedia samples from the Youngsan River Estuary, Korea: A comparison between freshwater and saltwater

Differences in the distribution, partitioning, and bioaccumulation characteristics of arsenicals between freshwater and saltwater systems remain poorly understood. To determine the characteristics of distribution and behavior of arsenicals, multimedia environmental samples including water, suspended particles, zooplankton, sediments, and porewater were collected from inner (five sites, freshwater) and outer (five sites, saltwater) regions of the estuary dike of the Youngsan River Estuary in South Korea (Nov., 2012). Six organic and inorganic forms of As were separated and measured using HPLC-ICP/MS equipped with an anion exchange column. Concentrations of arsenicals in water samples of the inner region (mean = 1.5 μg As L^-1) were significantly lower than in those of the outer region (mean = 5.2 μg As L^-1). Conversely, concentrations of As in suspended particles in the inner region (mean = 14 μg As g^-1) were much greater than in the outer region (mean = 5.7 μg As g^-1). The field-based distribution coefficient (K_d) for As depended strongly on salinity; relatively greater K_d values were found in freshwater compared with saltwater. The As^V was found to be the major form of As in all water and particle samples in both inner and outer regions. The zooplankton species were significantly distinguishable between the inner and outer regions; cladocerans were the most dominant species in freshwater and cyclopoida were predominantly found in saltwater. The As concentrations in zooplankton were shown to be particle-concentration dependent, suggesting that dietary exposure plays a substantial role in the bioaccumulation of As. Inorganic arsenicals, such as As^V and As^III were the most dominant forms found in zooplankton. Partitioning behavior of As between porewater and sediments was similar to that in water-particle distributions. The results of the present study enhance the understanding of As biogeochemistry in river and estuarine environments.

Bulk metal concentrations versus total suspended solids in rivers: Time-invariant & catchment-specific relationships

Suspended particles in rivers can act as carriers of potentially bioavailable metal species and are thus an emerging area of interest in river system monitoring. The delineation of bulk metals concentrations in river water into dissolved and particulate components is also important for risk assessment. Linear relationships between bulk metal concentrations in water (CW,tot) and total suspended solids (TSS) in water can be used to easily evaluate dissolved (CW, intercept) and particle-bound metal fluxes (CSUS, slope) in streams (CW,tot = CW + CSUS TSS). In this study, we apply this principle to catchments in Iran (Haraz) and Germany (Ammer, Goldersbach, and Steinlach) that show differences in geology, geochemistry, land use and hydrological characteristics. For each catchment, particle-bound and dissolved concentrations for a suite of metals in water were calculated based on linear regressions of total suspended solids and total metal concentrations. Results were replicable across sampling campaigns in different years and seasons (between 2013 and 2016) and could be reproduced in a laboratory sedimentation experiment. CSUS values generally showed little variability in different catchments and agree well with soil background values for some metals (e.g. lead and nickel) while other metals (e.g. copper) indicate anthropogenic influences. CW was elevated in the Haraz (Iran) catchment, indicating higher bioavailability and potential human and ecological health concerns (where higher values of CSUS/CW are considered as a risk indicator).