Historical contamination with a current problem: Can mining tailings enhance coastal arsenic pollution?

The coast of Espírito Santo state (Southeast Brazil) is recognized for its environmental arsenic (As) enrichment and, over the years, mining operations have potentialized it. We aimed to evaluate the effect of Rio Doce discharge on As inputs and the role of iron ore tailings from the Fundão dam disaster in enhancing As contamination in the marine sediment. Two scenarios were evaluated: Predisaster and Postdisaster; dry and wet conditions were considered in each period. High As concentrations were found in the Predisaster (28.44 ± 13.53 µg g-1 ), but a significant increase in As was remarkable during the Postdisaster in the wet season, one year after the disaster (maximum of 58.39 µg g-1 ; geoaccumulation index (Igeo ) Class 3, moderately severe pollution). On that occasion, iron (Fe) oxy-hydroxides from tailings were remobilized from the Rio Doce channel and deposited on the continental shelf bottom. Therefore, chemical interactions among Fe, As, and carbonates were enhanced, resulting in As and Fe coprecipitation and the trapping by carbonate adsorption. Rio Doce discharge seems to be the main factor in As inputs to the inner continental shelf when flooding do not occur previously in samplings, which allows further dispersion of contaminants, although this hypothesis should be tested further. Integr Environ Assess Manag 2024;20:159-168. © 2023 SETAC.

Drinking Water Supply in the Region of Antofagasta (Chile): A Challenge between Past, Present and Future.

Since the mid-nineteen century, when the first mining companies were established in the region of Antofagasta to extract saltpeter, mining managers and civil authorities have always had to face a number of problems to secure a water supply sufficient for the development of industrial activities and society. The unique features of the region, namely the scarcity of rainfall, the high concentration of arsenic in freshwaters and the increasing pressure of the mining sector, have made the supply of drinking water for local communities a challenge. In the 1950s, the town of Antofagasta experienced a serious drinking water crisis. The 300 km long aqueduct starting from the Toconce catchment, opened in 1958, temporarily ended this shortage of drinking water but created an even more dramatic problem. The concentration of arsenic in the water consumed by the population had grown by approx. ten times, reaching the value of 0.860 mg/L and seriously affecting people's health. The water treatment plants (WTPs) which were installed starting from the 1970s in the region (namely the Old and New Salar del Carmen in Antofagasta and Cerro Topater in Calama, plus the two recent desalination plants in Antofagasta and Tocopilla), have ensured, since 2014, that the drinking water coverage in the urban areas was practically universal (>99.9%). However, the rural areas have continued to experience significant shortcomings regarding their capacity to ensure the quality and continuity of the water supply service in the long run. Presently, approx. 42% of the rural population of the region of Antofagasta does not have a formal supply of drinking water. The recent amendments to the Chilean Water Code (March 2022) and the interventions carried out in the framework of the Agua Potable Rural (APR) program were intended to reduce the socio-ecological inequalities due to the lack of drinking water in the semi-concentrated and isolated rural population.

High arsenic tolerance in Brevundimonas aurantiaca PFAB1 from an arsenic-rich Indian hot spring

BACKGROUND Arsenic contamination in the ground water of rural India is a recurrent problem and decon tamination is mostly based on the chemical or physical treatments until now. Microbial bioremediation is eco-friendly, cheap, time-efficient and does not produce any toxic by-products. RESULT In the present study, a high arsenic tolerant bacteria Brevundimonas aurantiaca PFAB1 was iso lated from Panifala hot spring located in West Bengal, India. Previously Panifala was also reported to be an arsenic-rich hot spring. B. aurantiaca PFAB1 exhibited both positive arsenic reductase and arsenite oxidase activity. It was tolerant to arsenite up to 90 mM and arsenate up to 310 mM. Electron microscopy has proved significant changes in cellular micromorphology and stalk appearance under the presence of arsenic in growth medium. Bioaccumulation of arsenic in As (III) treated cells were 0.01% of the total cell weight, while 0.43% in case of As (V) treatment. CONCLUSIONS All experimental lines of evidence prove the uptake/accumulation of arsenic within the bac terial cell. All these features will help in the exploitation of B. aurantiaca PFAB1 as a potent biological weapon to fight arsenic toxicity in the near future

Environmental and human health risks of arsenic in gold mining areas in the eastern Amazon.

Knowledge of arsenic (As) levels in gold (Au) mining areas in the Amazon is critical for determining environmental risks and the health of the local population, mainly because this region has the largest mineral potential in Brazil and one of the largest in the world. The objective of this study was to assess the environmental and human health risks of As in tailings from Au exploration in the eastern Amazon. Samples were collected from soils and tailings from different exploration forms from 25 points, and the total concentration, pollution indexes and human health risk were determined. Concentrations of As were very high in all exploration areas, especially in tailings, whose maximum value reached 10,000 mg kg-1, far above the investigation value established by the Brazilian National Council of the Environment, characterizing a polluted area with high environmental risk. Exposure based on the daily intake of As demonstrated a high health risk for children and adults, whose non-carcinogenic risk indexes of 17.8, extremely above the acceptable limit (1.0) established by the United States Environmental Protection Agency. High levels of As in reactive fractions in underground, cyanidation, and colluvium mining areas, as well as extremely high gastric and intestinal bioaccessibility were found, suggesting that high levels may be absorbed by the local population. The results show that the study area is highly polluted through Au mining activities, putting the environment and population health at risk, and that there is an urgent need for intervention by the environmental control agencies for remediation.

Enhanced Arsenic Tolerance in Triticum aestivum Inoculated with Arsenic-Resistant and Plant Growth Promoter Microorganisms from a Heavy Metal-Polluted Soil.

In soils multi-contaminated with heavy metal and metalloids, the establishment of plant species is often hampered due to toxicity. This may be overcome through the inoculation of beneficial soil microorganisms. In this study, two arsenic-resistant bacterial isolates, classified as Pseudomonas gessardii and Brevundimonas intermedia, and two arsenic-resistant fungi, classified as Fimetariella rabenhortii and Hormonema viticola, were isolated from contaminated soil from the Puchuncaví valley (Chile). Their ability to produce indoleacetic acid and siderophores and mediate phosphate solubilization as plant growth-promoting properties were evaluated, as well as levels of arsenic resistance. A real time PCR applied to Triticum aestivum that grew in soil inoculated with the bacterial and fungal isolates was performed to observe differences in the relative expression of heavy metal stress defense genes. The minimum inhibitory concentration of the bacterial strains to arsenate was up to 7000 mg·L-1 and that of the fungal strains was up to 2500 mg·L-1. P. gessardi was able to produce siderophores and solubilize phosphate; meanwhile, B. intermedia and both fungi produced indoleacetic acid. Plant dry biomass was increased and the relative expression of plant metallothionein, superoxide dismutase, ascorbate peroxidase and phytochelatin synthase genes were overexpressed when P. gessardii plus B. intermedia were inoculated.

Screening and optimization of arsenic degrading bacteria and their potential role in heavy metal bioremediation / Triagem e otimização de bactérias que degradam arsê nicos e seu papel potencial na biorremediação de metais pesados

Industrialization has added extremely toxic metalloid arsenic into the environment which at high concentration severely threatens the biota. Naturally, some microbes possess the ability to bio-accumulate metals and also to transform arsenite (As III) a toxic form to a non-toxic arsenate As V. The present study aimed to isolate arsenic resistant bacterias from the arsenic contaminated soil and water. Among eleven bacterial isolates, three FAs 1, 4 and 9 exhibited tolerance against sodium arsenite at 100mM concentration by achieving growth of 7.48×109,1.57×109 and 2.23×109 C.F.U./ml, respectively. Optimization at differentconditions such as temperature, pH and arsenic concentration revealed high arsenic tolerance from isolate FAs 4 (5.33×108) at 37°C and FAs 1 (4.43×108 C.F.U./ml) at pH 7. Arsenic resistance at optimum conditions for the bacterial strains FAs 1, FAs 4 and FAs 9 showed maximum growth at 80mM concentration of arsenite. These bacterial isolates did not show redox ability to oxidize arsenite As III to arsenate As V. However bacterial isolates FAs 1, FAs 4 and FAs 9 were able to accumulate arsenic 39.16, 148 and 125 µ g/L on the 4th, 3rd and 5thday of incubation, respectively. The isolates FAs 1, FAs 4 and FAs 9 were identified as Gram negative non endospore forming rods. In future, these novel isolates possess a great potential in biotechnology field, as bioremediation of arsenic contaminated soil and water can be done by employing arsenic accumulating bacteria which is an eco-friendly and cost effective method.

A industrialização adicionou arsênico metalóide extremamente tóxico ao ambiente que, em alta concentração, ameaça severamente a biota. Naturalmente, alguns micróbios possuem a capacidade de bio-acumular metais e também transformar arsenito (As III) uma forma tóxica a um arsenato não-tóxico Como V. O presente estudo visa o isolamento de bactérias resistentes ao arsênico do solo contaminado com arsênico e água . Entre onze isolados bacterianos, três FAs 1, 4 e 9 exibiram tolerância à concentração de 100 mM de arseatura de sódio, obtendo crescimento de 7,48 × 109,157 × 109 e 2,23 × 109 C.F.U./ml, respectivamente. Otimização em diferentes condições como temperatura, pH e concentração de arsênio revelaram alta tolerância ao arsênico do isolado FAs 4 (5,33 × 108) a 37 ° C e FAs 1 (4,43 × 108 UFC / ml) em pH 7. Resistência ao arsênico em condições ótimas para as cepas bacterianas FAs 1, FAs 4 e FAs 9 apresentaram crescimento máximo na concentração de 80 mM de arsenito. Estes isolados bacterianos não mostraram capacidade redoxpara oxidar o arsenito As III para arseniar como V. No entanto, os isolados bacterianos FAs 1, FAs 4 e FAs 9 foram capazes de acumular arsênico 39,16, 148 e 125 µ g / L no 4º, 3º e 5º dia de incubação, respectivamente. Os isolados FAs 1, FAs 4 e FAs 9 foram identificados como bastonetes gram-negativos não endoscópicos. No futuro, esses novos isolados possuem um grande potencial no campo da biotecnologia, já que a biorremediação de solo e água contaminados com arsênico pode ser feita empregando-se bactérias que acumulam arsênico, o que é um método ecologicamente correto e econômico.

Arsenic contamination in rainwater harvesting tanks around Lake Poopó in Oruro, Bolivia: An unrecognized health risk.

Drinking water sources used by largely rural and indigenous communities around Lake Poopó in the Bolivian Altiplano are impacted by drought and a combination of natural and anthropogenic mining-related contaminants putting the long-term health and sustainability of these communities at risk. As an alternative drinking water source, 18 rainwater harvesting tanks connected to corrugated iron roofs, each with a first-flush system, were installed in 5 communities around the lake. The water quality of these tanks was monitored over 22 months and compared to alternative unprotected surface and groundwater sources the communities previously relied upon. The rainwater quality was found to be within the Bolivian and World Health Organization (WHO) limits, except for elevated arsenic concentrations two times the recommended health limit (0.01 mg/L). Tracing arsenic concentrations through the rainwater flow-path showed that the elevated arsenic concentrations result from mineral dust particles entering the system when rainwater interacts with the roof catchment, with arsenic leaching out. A leaching test showed that 24 h of contact time between 200 mL of water and <1 g of roof dust is enough to raise the arsenic levels of the water above the Bolivian and WHO limit. Currently, no other research exists evaluating the quality of harvested rainwater in the Bolivian Altiplano for human consumption or the source of arsenic in harvested water. This represents a significant knowledge gap for future development practitioners and programs addressing water security around Lake Poopó and the wider region. As a result, it is strongly recommended to include arsenic as a standard parameter in water quality monitoring of rainwater harvesting projects, especially in active mining regions, and to optimize strategies to minimize roof dust from entering the collection system.

Arsenic-hypertolerant and arsenic-reducing bacteria isolated from wells in Tucumán, Argentina.

Arsenic-hypertolerant bacteria were isolated from arsenic-contaminated well water from the village of Los Pereyra in Tucumán province, Argentina. Microorganisms that biotransform arsenic are a major factor in arsenic mobilization in contaminated aquifers. Groundwater analyses showed a level of arsenic contamination (mean concentration of 978 µg·L-1) that exceeds the safe drinking water limit of 10 µg·L-1 recommended by the World Health Organization and the Argentine Food Code. There was considerable spatial variability in the concentration of arsenic in each of the wells analyzed and in the distribution of the major anions HCO3-, SO42-, and Cl-. Eighteen bacterial strains were characterized. Six strains belonging to the Actinobacteria phylum were able to grow in media with 20 mmol·L-1 As(III) or 200 mmol·L-1 As(V) and were also highly resistant to Cr, Cd, and Cu. Their ability to biotransform arsenic was examined by speciation of the products by high-performance liquid chromatography inductively coupled plasma mass spectrometry. In addition, two strains, Brevibacterium sp. strain AE038-4 and Microbacterium sp. strain AE038-20, were capable of aerobic arsenate reduction, which suggests that these strains could increase the mobility of arsenic by formation of more mobile As(III).

Evaporative concentration of arsenic in groundwater: health and environmental implications, La Laguna Region, Mexico.

High arsenic concentrations in groundwater have been documented in La Laguna Region (LLR) in arid northern Mexico, where arsenic poisoning is both chronic and endemic. A heated debate has continued for decades on its origin. LLR consisted of a series of ancient connected lakes that developed at the end of a topographic depression under closed basin conditions. This study addresses the isotopic, chemical composition of the groundwater and geochemical modeling in the southeasternmost part of the LLR to determine the origin of arsenic. Groundwater samples were obtained from a carbonate and granular aquifers and from a clayey aquitard at terminal Viesca Lake. Results show that groundwater originated as meteoric water that reached the lakes mainly via abundant springs in the carbonate aquifer and perennial flooding of the Nazas-Aguanaval Rivers. Paleo-lake water underwent progressive evaporation as demonstrated by the enrichment of δ18O, δ2H and characteristic geochemical patterns in the granular aquifer and aquitard that resulted in highly saline (>90,000 mS/cm), arsenic-rich (up to 5000 µg/L) paleo-groundwater (>30,000 years BP). However, adsorption or co-precipitation on iron oxides, clay-mineral surfaces and organic carbon limited arsenic concentration in the groundwater. Arsenic-rich groundwater and other solutes are advancing progressively from the lacustrine margins toward the main granular aquifer, due to reversal of hydraulic gradients caused by intensive groundwater exploitation and the reduction in freshwater runoff provoked by dam construction on the main rivers. Desorption of arsenic will incorporate additional concentrations of arsenic into the groundwater and continue to have significant negative effects on human health and the environment.