High Concentrations Of Arsenic Research Articles

Potentially toxic elements in different tissues of great cormorant (Phalacrocorax carbo) at a wetland area

Concentrations of 4 potentially toxic elements (As, Cd, Hg, Pb) were investigated in the feather, liver, kidney, and bone of great cormorants (Phalacrocorax carbo). The tissue samples were taken at the Central Tisza - Jászság Nature Conservation Area in Hungary. They were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The goal of the investigation was to analyse the metal burden of the above-mentioned elements in the various tissues of these wild birds and to provide important information for monitoring the environmental pollution.Amongst the examined potentially toxic elements no statistical gender difference was observed, so the data were not separated based on them during the statistical analysis. The concentration of mercury was the highest in the feather, followed by the liver, kidney, and bone. The lead was detected in the feather with the highest level followed by the kidney, liver, and bone. The cadmium was determined in all investigated tissues with the next descending order: kidney > bone > liver > feather. Highest arsenic concentration was measured in the feather, followed by liver, kidney, and bone with the same concentration.The detected concentrations of the investigated potentially toxic elements in different tissues of great cormorants (feathers, liver, kidney, bone) means that the living area of this birds is not highly contaminated to induce health problems or toxic signs, or even other undesirable effect in the animals.

Littoral sediment arsenic concentrations predict arsenic trophic transfer and human health risk in contaminated lakes.

Lake sediments store metal contaminants from historic pesticide and herbicide use and mining operations. Historical regional smelter operations in the Puget Sound lowlands have resulted in arsenic concentrations exceeding 200 μg As g-1 in urban lake sediments. Prior research has elucidated how sediment oxygen demand, warmer sediment temperatures, and alternating stratification and convective mixing in shallow lakes results in higher concentrations of arsenic in aquatic organisms when compared to deeper, seasonally stratified lakes with similar levels of arsenic pollution in profundal sediments. In this study we examine the trophic pathways for arsenic transfer through the aquatic food web of urban lakes in the Puget Sound lowlands, measuring C and N isotopes-to determine resource usage and trophic level-and total and inorganic arsenic in primary producers and primary and secondary consumers. Our results show higher levels of arsenic in periphyton than in other primary producers, and higher concentrations in snails than zooplankton or insect macroinvertebrates. In shallow lakes arsenic concentrations in littoral sediment are similar to deep profundal sediments due to arsenic remobilization, mixing, and redeposition, resulting in direct arsenic exposure to littoral benthic organisms such as periphyton and snails. The influence of littoral sediment on determining arsenic trophic transfer is evidenced by our results which show significant correlations between total arsenic in littoral sediment and total arsenic in periphyton, phytoplankton, zooplankton, snails, and fish across multiple lakes. We also found a consistent relationship between percent inorganic arsenic and trophic level (determined by δ15N) in lakes with different depths and mixing regimes. Cumulatively, these results combine to provide a strong empirical relationship between littoral sediment arsenic levels and inorganic arsenic in edible species that can be used to screen lakes for potential human health risk using an easy, inexpensive sampling and analysis method.

Enrichment mechanism of arsenic in deep confined aquifers of Guide Basin under the influence of geothermal activities

High arsenic (As) concentrations in groundwater affected by geothermal activity have been reported worldwide, but the genesis mechanism is not adequately understood. To address this issue, 22 groundwater samples and 69 sediment samples were collected from the Guide basin in northwest China for hydrochemical and geochemical analyses and laboratory experiments. Results indicated that Fe/Mn oxide minerals were the main carriers of As, which was proved by a positive correlation between As and Fe or Mn in sediments. Analysis of hydrologic characteristics showed that direct contribution of As from geothermal water to confined groundwater was probably not significant in the Guide basin. Results of laboratory experiments indicated that As release from aquifer sediments was accelerated by increased temperature under different pH and ORP conditions. Raising temperature may stimulate the release of As by promoting dissolutions of As-bearing Fe (hydr)oxides, weathering of As-bearing silicates and As desorption from sediments into groundwater. The research results can not only increase the understanding of arsenic enrichment mechanism in groundwater under geothermal geological background, but also provide a scientific basis for other high-As groundwater with similar geological background in the world.

Superfood consumers' exposure to selected heavy metals.

Background: Superfood products are important components of the human diet, which may contain toxic heavy metals that have no beneficial function in the human body (e.g., cadmium, arsenic, mercury). Therefore, due to the high demand for these foods, maintaining their safety is a significant public health concern, resulting in an increasing number of studies in the field of health risk assessment due to population exposure to heavy metals. Aim: The aim of the study was to determine the concentration of selected heavy metals in individual superfood products. Methods: The research material consisted of 48 samples of selected superfood products such as flaxseed, chia seed, black cumin, goji berries, buckwheat, millet, almonds, quinoa and green tea. The collected samples were subjected to the mineralization process. In addition, an exposure assessment was performed by calculating the hazard quotient (HQ). Statistical analysis was performed using Statistica software for cadmium and arsenic. Results: The highest level of cadmium was observed in a sample of flaxseed (ground)-0.35 mg/kg. Again, the highest concentration of arsenic was found in green tea bags (21.94 mg/kg). The exposure assessment showed that the risk of adverse health effects is likely to occur with the consumption of flaxseed, almonds, quinoa and green tea at both the assumed average and maximum arsenic concentrations (HQ > 1). Conclusions: There are many foods on the market that contain heavy metals. The accumulation of various heavy metals in agricultural soils and edible crops should be regularly assessed to minimize public health problems.

Risk assessment of the negative impact of consuming water with high arsenic concentrations on public health in the Republic of Dagestan

The consumption of contaminated water by the population is a serious issue that has long been the focus of attention of hygienists and ecologists, and has acquired social significance not only in individual regions, but also on a national scale. The extraction, processing, filtration, and logistics component of clean high-quality water is a priority, as this factor has the greatest impact on a person’s health and ability to work. On the territory of the Republic of Dagestan, there is the largest underground water storage, the Terek-Kuma Artesian Basin (TKB) (18.9 thousand km²), which occupies the northern part of the region and the Caspian Sea drainage basin of small rivers in the southern foothills, which is 37.5 % of the total area of the Republic of Dagestan. The storage is actively used by the local population for household and drinking purposes and supplies the largest populated areas of the Republic. More than 292,000 thousand people live in the TKB zone, of whom about 58,000 thousand are children. The hydrochemistry of the underground mineral waters of the TKBis largely determined by the structural and tectonic zoning of Dagestan, therefore the waters in different parts of the basin differ significantly in composition. Today, there is a problem of the formation of an unfavorable water factor due to the presence of increased concentrations of arsenic in the composition of TKB water. Our research work is aimed at determining the impact of this factor on public health.

Bioaccumulation of contaminants in Scarabaeidae and Silphidae beetles at sites polluted by coal combustion residuals and radiocesium

Anthropogenic contamination from coal-fired power plants and nuclear reactors is a pervasive issue impacting ecosystems across the globe. As a result, it is critical that studies continue to assess the accumulation and effects of trace elements and radionuclides in a diversity of biota. In particular, bioindicator species are a powerful tool for risk assessment of chemically contaminated habitats. Using inductively coupled plasma mass spectrometry (ICP-MS) and auto-gamma counting, we analyzed trace element and radiocesium contaminant concentrations in Scarabaeidae and Silphidae beetles (Order: Coleoptera), important taxa in decomposition and nutrient cycling, at contaminated and reference sites on the Savannah River Site, South Carolina, U.S. Our results revealed variability in trace element concentrations between Scarabaeidae and Silphidae beetles at uncontaminated and contaminated sites. Compared to Scarabaeidae, Silphidae had higher levels of chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn). Unexpectedly, concentrations of Cr, Cu, and Ni were higher in both taxa at the uncontaminated sites. Scarabaeidae and Silphidae beetles at the coal combustion waste site consistently had high concentrations of arsenic (As), and Scarabaeidae had high concentrations of selenium (Se). Of the 50 beetles analyzed for radiocesium levels, two had elevated radioactivity concentrations, both of which were from a site contaminated with radionuclides. Our results suggest carrion beetles may be particularly sensitive to bioaccumulation of contaminants due to their trophic position and role in decomposition, and thus are useful sentinels of trace element and radionuclide contamination.

Adsorptive behavior of Fe/Zn-modified nanobiochar for arsenic removal from naturally contaminated groundwater

Global groundwater is frequently discovered to have high arsenic (As) concentrations, critically endangered and potentially toxic to aquatic organisms and humans. This work investigates As(V) adsorption using raw nanobiochar (RnBC) and activated magnetic nanobiochar (AMnBC), which are synthesized via pre-treating rice straw biomass with ZnCl2 and FeCl3 and pyrolyzing at 500 °C, followed by ball milling. The highest adsorption capacity for AMnBC and RnBC was 130 μg/g and 38.67 μg/g, respectively, at alkaline water chemistry to mimic natural groundwater conditions. Different functional groups contributed by modifications are evident with As(V) adsorption using RnBC and AMnBC. Multilayer chemisorption may explain the adsorption of As(V) on biochar surfaces, as Freundulich isotherm and pseudo-second-order kinetic model are suggested. The synthesis cost for AMnBC and RnBC was $0.0147/g and $0.0099/g, respectively, which helped to determine the most effective and efficient method for As(V) adsorption. In this study, natural As-contaminated groundwater collected from Patna, Bihar (India), was treated for As(V) removal using AMnBC in natural environments. Thus, this study recommends that cost-effective modified biochar can effectively be used for As(V) elimination from naturally contaminated groundwater as well as surface water.

Effective reduction and recovery of As(III) and As(V) from alkaline wastewater by thiourea dioxide: Efficiency and mechanism.

For alkaline wastewater with high arsenic concentration, the traditional lime precipitation inevitably produces large amounts of hazardous waste. Herein, a heat-activated reduction method employing thiourea dioxide (TDO) as the reductant was proposed to efficiently remove and recover As(III)/As(V) from alkaline wastewater in the form of valuable As(0). More than 99.9% of As(III)/As(V) (2-400mM) were reduced to As(0) with a high purity of more than 99.5 wt% by TDO within 30min. The highly reductive eaq- and SO2- radical generated during TDO decomposition contribute to the arsenic reduction, and the contribution ratios of eaq- and SO2- radical were estimated to be approximately 57.6% and 42.4% for As(III) removal and 62.2% and 37.8% for As(V) removal, respectively. The arsenic reduction was greatly improved by increasing pH and temperature, which could accelerate the cleavage of C-S bond in TDO for the eaq- and SO2- formation. The presence of dissolved oxygen, which can not only scavenge eaq-/SO2- but also directly oxidize SO22-, had a negative effect on the arsenic removal. The presence of CO32- slightly suppressed the arsenic removal due to the eaq- scavenging effect while SiO32-, PO43-, Cl-, SO42- and NH4+ had negligible effects. The proposed method was a potential technology for the efficient removal and reduction of arsenic in alkaline wastewater.

Upward Trends and Lithological and Climatic Controls of Groundwater Arsenic, Fluoride, and Nitrate in Central Mexico

Central Mexico is known for its high concentrations of geogenic arsenic (As) and fluoride (F−) in the groundwater; however, concentrations vary widely within the region. To identify specific hydrogeological processes that cause these variations, the study area was divided into four sections, each section with a particular lithology, climate, and land use. Nitrate was added to the analysis as a common anthropic contaminant in this area as one that is indicative of human and agricultural activities. Concentration maps, Na-normalized diagrams, Spearman correlation, and upward trend analyses were applied to 77 wells distributed across the four sections. Specific patterns of concentration emerged according to climate and the lithology of the exposed rocks. A sharp reduction of F− concentrations in the section where carbonate rocks outcrop suggested co-precipitation of F− with calcite. The Mann–Kendall method detected upward trends in 5 out of 54 wells for As and NO3–N and three for F− at a 95% probability level. Several wells with upward trends of As and NO3–N overlapped. Only one well showed a downward trend for NO3–N. The results show the degree to which lithology and climate affect groundwater quality, information that leads to a better understanding of the processes (and health hazards) that govern As, F−, and NO3–N concentrations, which could be construed to include the potential effect of human activities such as overfertilization and altering groundwater residence time via groundwater withdrawals.

Arsenic contamination and rare earth element composition of acid mine drainage impacted soils from South Africa

Acid mine drainage (AMD) impacted soils occur as soils near weathered pyritic mine tailings, directly receiving AMD or in proximity to AMD polluted waters. They pose environmental and human health risks and present challenges to restoration strategies for better land use management. This study investigated the chemical composition and geochemical evidence of AMD impact in four top soils from gold and coal mining regions near Johannesburg, South Africa with a focus on characterising metal contamination and rare earth element (REE) content. Soil physico-chemical properties (pH, electrical conductivity, texture, cation exchange capacity, carbon content, and sulfate) were measured and analysed and pseudo-total elemental contents were determined from a microwave digestion analysed by ICP-MS. The results showed evidence of soil acidification and exceedingly high sulfate (>7000 mg kg−1) and calcium (>200 g kg−1) contents. High arsenic contents (>300 mg kg−1) were found for some of the samples, exceeding the national soil screening value of 23 mg kg−1. Total REE content ranged from 51.7 to 110 mg kg−1 and favoured the light over heavy rare earth elements. The results suggest that there are complex dynamics between AMD and soil element fractions. Arsenic was unexpected as it had not previously been well documented in AMD polluted groundwater, surface waters, or mine seepage from the region, and REEs, with which AMD is often enriched, were not retained in the topsoil samples. These novel findings indicate major challenges to post-mining land rehabilitation.

Effects of dietary inclusion of 3 Nordic brown macroalgae on enteric methane emission and productivity of dairy cows

Macroalgae are receiving increased attention as antimethanogenic feed additives for cattle, but most in vivo studies are limited to investigating effects of the red macroalgae Asparagopsis spp. Hence, this study aimed to investigate the CH4 mitigating potential of 3 brown macroalgae from the Northern Hemisphere when fed to dairy cows, and to study the effects on feed intake, milk production, feed digestibility, and animal health indicators. The experiment was conducted as a 4 × 4 Latin square design using 4 lactating rumen, duodenal, and ileal cannulated Danish Holstein dairy cows. The cows were fed a total mixed ration (TMR) without any macroalgae or the same TMR diluted with, on a dry matter basis, either 4% ensiled Saccharina latissima, 4% Ascophyllum nodosum (NOD), or 2% Sargassum muticum (MUT). Each period consisted of 14 d of adaptation, 3 d of digesta and blood sampling, and 4 d of gas exchange measurements using respiration chambers. Milk yield and dry matter intake (DMI) were recorded daily. Blood was sampled on d 13 and 16 and analyzed for health status indicators. None of the 3 species affected the CH4 emission. Moreover, milk yield and DMI were also unaffected. Total-tract digestibility of crude protein was significantly lower for NOD compared with other diets, and additionally, the NOD diet also tended to reduce total-tract digestibility of neutral detergent fiber compared with MUT. Blood biomarkers did not indicate negative effects of the dietary inclusion of macroalgae on cow health. In conclusion, none of the 3 brown macroalgae reduced CH4 emission and did not affect DMI and milk production of dairy cows, whereas negative effects on the digestibility of nutrients were observed when A. nodosum was added. None of the diets would be allowed to be fed in commercial dairy herds due to high contents of iodine, cadmium, and arsenic.

Upcycling of recycled minerals from sewage sludge through black soldier fly larvae (Hermetia illucens): Impact on growth and mineral accumulation

Phosphorous (P) resources are finite. Sewage sludge recyclates (SSR) are not only of interest as plant fertilizer but also as potential source of minerals in animal nutrition. However, besides P and calcium (Ca), SSR contain heavy metals. Under EU legislation, the use of SSR derivatives in animal feed is not permitted, but given the need to improve nutrient recycling, it could be an environmentally sound future mineral source. Black soldier fly larvae (BSFL) convert low-grade biomass into valuable proteins and lipids, and accumulate minerals in their body. It was hypothesized that BSFL modify and increase their mineral content in response to feeding on SSR containing substrates. The objective was to evaluate the upcycling of minerals from SSR into agri-food nutrient cycles through BSFL. Growth, nutrient and mineral composition were compared in BSFL reared either on a modified Gainesville fly diet (FD) or on FD supplemented with either 4% of biochar (FD + BCH) or 3.6% of single-superphosphate (FD + SSP) recyclate (n = 6 BSFL rearing units/group). Larval mass, mineral and nutrient concentrations and yields were determined, and the bioaccumulation factor (BAF) was calculated. The FD + SSP substrate decreased specific growth rate and crude fat of BSFL (P < 0.05) compared to FD. The FD + SSP larvae had higher Ca and P contents and yields but the BAF for Ca was lowest. The FD + BCH larvae increased Ca, iron, cadmium and lead contents compared to FD. Larvae produced on FD + SSP showed lower lead and higher arsenic concentration than on FD + BCH. Frass of FD + BCH had higher heavy metal concentration than FD + SSP and FD (P < 0.05). Except for cadmium and manganese, the larval heavy metal concentration was below the legally permitted upper concentrations for feed. In conclusion, the SSR used could enrich BSFL with Ca and P but at the expense of growth. Due to the accumulation of Cd and Mn, BSFL or products thereof can only be a component of farmed animal feed whereas in BSFL frass heavy metal concentrations remained below the upper limit authorized by EU.

An identification of arsenic retention mechanisms in column filtration systems packed with limestone

The high concentrations of arsenic in the groundwater of Zimapán, Hidalgo, Mexico, have led to the search for options that contribute to resolving this problem. In this study, we use percolation columns to remove arsenic in aqueous solutions in coexistence with ions such as fluorides, chlorides, sulfates, or bicarbonates. This filtration technique is effective and low cost since the filter material is a native limestone belonging to the Soyatal Formation of the Upper Cretaceous. This article characterizes the mechanisms of arsenic removal by calcite, the limestone's main constituent, through X-ray absorption spectroscopy (XAS). The main processes of arsenic retention in calcite are adsorption (forming corner-sharing inner-sphere surface complexes) and coprecipitation (replacing AsO4 in the carbonate site).

Arsenic Levels in Soil and Rice and Health Risk Assessment via Rice Consumption in Industrial Areas of East Java, Indonesia

Industrial use of arsenic can potentially cause environmental problems in water, soil, and air. Arsenic is one of heavy metals that is highly toxic and carcinogenic. Arsenic contamination in the environment is harmful to human health because it can enter the body through the food chain. This study determined the concentration of arsenic in soil and rice and its impact on human health risks. Sampling was carried out in several East Java industrial cities or districts, for instance, Gresik, Mojokerto, Sidoarjo, Nganjuk, Ponorogo, and Surabaya. The measurement of arsenic in soil was done using Energy Dispersive X-Ray fluorescence (EDXRF), while the measurement of arsenic in rice was done by Total X-Ray Fluorescence (TXRF). The results showed that arsenic concentration in several areas of East Java has varying levels. The concentration of arsenic in soil was highest in Gresik (13,786 mg/kg). The highest arsenic concentration in rice was found in Mojokerto (0.154 mg/kg). The results of risk assessment in this study showed that the Hazard Quotient (HQ) value was &gt;1 and the Excess Cancer Risk (ECR) was &gt;10-4 in all areas at the age of children &lt;2 years. Health risk assessment of adults showed HQ&gt;1 and ECR&gt;10-4 in several areas of East Java. This indicates that consumption of rice contaminated with arsenic has the potential to pose non-carcinogenic and carcinogenic health risks.

An updated systematic review and dose-response meta-analysis on the relation between exposure to arsenic and risk of type 2 diabetes

Arsenic is among the most critical environmental toxicants associated with many human disorders. However, its effect on type 2 diabetes mellitus (T2DM) is contradictory. This systematic review and dose-response meta-analysis aim to update information on the association between arsenic exposure and the risk of T2DM. The sample type (drinking water, urine, blood, and nails) conducted the subgroup analysis. Evaluation of the high vs. low arsenic concentrations showed a significant association between drinking water arsenic (OR: 1.58, 95% CI: 1.20–2.08) and urinary arsenic (OR: 1.37, 95% CI: 1.24–1.51) with the risk of T2DM. The linear dose-response meta-analysis showed that each 1 μg/L increase in levels of drinking water arsenic (OR: 1.01, 95% CI: 1.00–1.01) and urinary arsenic (OR: 1.01, 95% CI: 1.00–1.02) was associated with a 1% increased risk of T2DM. The non-linear dose-response analysis indicated that arsenic in urine was associated with the risk of T2DM (Pnon-linearity<0.001). However, this effect was not statistically significant for arsenic in drinking water (Pnon-linearity=0.941). Our findings suggest that blood arsenic was not significantly linked to the increased risk of T2DM in high vs. low (OR: 1.21, 95% CI: 0.85–1.71), linear (OR: 1.04, 95% CI: 0.99–1.09), and non-linear (Pnon-linearity=0.365) analysis. Also, nail arsenic was not associated with the risk of T2DM in this meta-analysis (OR: 1.33, 95% CI: 0.69–2.59). This updated dose-response meta-analysis indicated that arsenic exposure was significantly correlated with the risk of T2DM.

Assessment of the Hydrophysical and Hydrochemical Characteristics of Lake Burabay (Akmola Region, North Kazakhstan)

This paper shows the results of a study on the morphometric, hydrophysical, and hydrochemical indicators of Lake Burabay, North Kazakhstan. The Burabay Protected Area, also known as Burabay National Park or Kokshetau National Park, is a protected natural area located in the north of Kazakhstan. It encompasses a diverse landscape characterized by lakes, forests, and unique rock formations. This analysis includes an eco-toxicological assessment of the hydrochemical composition of waters and benthal deposits by studying the content of metals. The degree of mineralization, ionic composition of water, hydrogen index, pollution index, and water quality class were also determined. Reductions in the area and depth of the lake were identified. The pollution index is 1.5–1.7, which belongs to class 3—moderately polluted. Relatively high concentrations of cadmium, nickel, copper, and arsenic were found in the lake sediments. Therefore, Lake Burabay and its surrounding ecosystem face certain environmental risks and potential water pollution. Although the increase in the number of tourists did not have a significant impact on the water pollution index in Lake Burabay, some of the common threats that impact the area are induced by touristic development, agricultural practices and industrial pollution. Significant efforts should be made to reduce these risks using the environmental indicators as a reference for control environmental quality.

Occurrence, speciation, and controls on arsenic mobilization in the alluvial aquifer system of the Ghaghara basin, India.

High concentrations of arsenic (As) in groundwater are among the long-standing environmental problems on the planet. Due to adverse impacts on the human and aquatic system, characterization and quantification of individual inorganic As species are crucial in understanding the occurrence, environmental fate, behaviour, and toxicity in natural waters. This study presents As concentration and its speciation As(III) and As(V) data, including the interrelationship with other major and trace aqueous solutes from parts of the Ghaghara basin, India. More than half (57%) of the groundwater samples exhibited elevated As concentrations (> 10μg/L), whereas 67.4% of samples have higher As(III) values relative to As(V), signifying a potential risk of As(III) toxicity. The elevated concentration of As was associated with higher Fe, Mn, and HCO3-, especially in samples from shallow well depth. PHREEQC modeling demonstrates the presence of mineral phases such as hematite, goethite, rhodochrosite, etc. Therefore, it is inferred that the release of As from sediment particles into pore water via microbially mediated Fe/Mn oxyhydroxides, and As(V) reduction processes mainly control high As concentrations. The heavy metal pollution indices (HPI) and (HEI) values revealed heavy metal pollution in low-lying areas deposited by relatively younger sediments along the Ghaghara River. Large-scale agricultural practices, overexploitation of groundwater, and indiscriminate sewage disposal, in addition to geogenic factors, cannot be ruled out as potential contributors to As mobilization in the region. This study recommends conducting seasonal hydrogeochemical monitoring and investigating regional natural background levels of As, to precisely understand the controlling mechanistic pathways of As release.

Release of arsenic during riverbank filtration under anoxic conditions linked to grain size of riverbed sediments

Geogenic arsenic contamination of groundwater poses a health threat to millions of people worldwide, particularly in Asia. Riverbank filtration (RBF) is a pre-treatment technique that aims to improve surface water quality through natural processes during water infiltration before abstraction. A study in Hanoi, Vietnam is presented, where the water quality of 48 RBF wells from 5 large well fields located in the Pleistocene aquifer along the Red River was analyzed. >80 % of the wells had arsenic concentrations above the WHO limit of 10 μg/l. The riverbed sediment and riverbed pore-water from 23 sites along a stretch of 30 km of the Red River near the well fields was also analyzed. Muddy riverbeds were found to be a hotspot for arsenic release. Already at a 30 cm depth from the riverbed sediment surface, the pore-water at many sites had high concentrations of arsenic (>100 μg/l). Arsenic concentrations in the pore-water of sites where mud lenses were present in the riverbed were significantly higher compared to sites with sandy riverbeds. At well fields along stretches of the Red River where riverbed was mostly muddy, higher arsenic concentrations were found than at well fields where the riverbed was mostly sandy. This indicates that river muds deposition and river morphology can influence arsenic concentrations in the aquifer in Hanoi and potentially other RBF sites in regions with geogenic arsenic contamination. At the end, recommendations regarding site selection of new potential RBF wells in affected regions is given.

Metal mixture exposure and the risk for immunoglobulin A nephropathy: Evidence from weighted quantile sum regression.

Immunoglobulin A nephropathy (IgAN) is the most common type of glomerulonephritis in adults worldwide. Environmental metal exposure has been reported to be involved in the pathogenic mechanisms of kidney diseases, yet no further epidemiological study has been conducted to assess the effects of metal mixture exposure on IgAN risk. In this study, we conducted a matched case‒control design with three controls for each patient to investigate the association between metal mixture exposure and IgAN risk. A total of 160 IgAN patients and 480 healthy controls were matched for age and sex. Plasma levels of arsenic, lead, chromium, manganese, cobalt, copper, zinc, and vanadium were measured using inductively coupled plasma mass spectrometry. We used a conditional logistic regression model to assess the association between individual metals and IgAN risk, and a weighted quantile sum (WQS) regression model to analyze the effects of metal mixtures on IgAN risk. Restricted cubic splines were used to evaluate overall associations between plasma metal concentrations and estimated glomerular filtration rate (eGFR) levels. We observed that except for Cu, all the metals analyzed were nonlinearly associated with decreased eGFR, and higher concentrations of arsenic and lead were associated with elevated IgAN risk in both single-metal [3.29 (1.94, 5.57), 6.10 (3.39, 11.0), respectively] and multiple-metal [3.04 (1.66, 5.57), 4.70 (2.47, 8.97), respectively] models. Elevated manganese [1.76 (1.09, 2.83)] levels were associated with increased IgAN risk in the single-metal model. Copper was inversely related to IgAN risk in both single-metal [0.392 (0.238, 0.645)] and multiple-metal [0.357 (0.200, 0.638)] models. The WQS indices in both positive [2.04 (1.68, 2.47)] and negative [0.717 (0.603, 0.852)] directions were associated with IgAN risk. Lead, arsenic, and vanadium contributed significant weights (0.594, 0.195, and 0.191, respectively) in the positive direction; copper, cobalt, and chromium carried significant weights (0.538, 0.253, and 0.209, respectively). In conclusion, metal exposure was related to IgAN risk. Lead, arsenic, and copper were all significantly weighted factors of IgAN development, which may require further investigation.

Effects of Varied Forms of Arsenic Stress on Seedling Growth and Arsenic Distribution in Honeysuckle Plants

At present, soil arsenic contamination is one of the prominent environmental problems. The arsenic concentration in honeysuckle exceeds the standard levels, thus affecting the quality of traditional Chinese medicine. In this study, the hydroponic method was employed to explore the effect of organic arsenic (dimethyl arsenic) and trivalent inorganic arsenic (NaAsO2) on the growth of honeysuckle plants. The study demonstrated that low concentrations of inorganic arsenic (10–20 mg/L) and 10–50 mg/L organic arsenic had a stimulating effect on the growth of honeysuckle plants. The activities of antioxidant enzymes (peroxidase and catalase) increased correspondingly. However, the antioxidant system in honeysuckle plants was damaged under high concentrations of inorganic arsenic (20–40 mg/L) and 50–70 mg/L organic arsenic. On exposure to 30 mg/L NaAsO2 or 50 mg/L dimethyl arsenic acid for 10 days, the activities of peroxidase and catalase, as well as the malondialdehyde content, increased with prolonged exposure. The micro X-ray fluorescence analysis revealed that the accumulated arsenic in the roots was transported from the central vascular cylinders to the outer part of the root with the increase in concentration and exposure duration of inorganic arsenic. However, organic arsenic stress did not result in significant variations in the distribution of arsenic with increasing concentrations of arsenic. The arsenic element was predominantly located in the middle woody part of the root. The distributions of arsenic in the stems and leaves, in terms of organic and inorganic arsenic stresses, were similar, with accumulation primarily in the cortex of the stem and veins of the leaves. As a commonly used bulk traditional Chinese medicine, honeysuckle has a wide range of product quality issues. Hence, exploring the absorption, distribution, and transport trends of heavy metals such as arsenic in the plant body is of great significance for scientifically evaluating the impact of heavy metal pollution on the quality of medicinal materials and exploring ways to reduce the accumulation of heavy metals in the medicinal parts of plants.