Arsenic, copper, and chromium from treated wood products in the U.S. disposal sector

Change in water quality in an Amazonian microbasin: ecological and human health implications

The decline in the quality of water resources in the Amazon is very rapid in cities suffering from unplanned urban growth. The region has two defined seasons, winter (wet) and summer (dry), which directly affect the behavior of contaminants in aquatic ecosystems. The aim of this study was to assess the ecological and human health risks associated with the use of the watershed. In addition, an ecological index was proposed: the Quality Index for Aquatic Life, for the risk of contaminants to aquatic life. Sampling was carried out at six points in the Juá watershed. Physicochemical parameters, major anions, metals and total phosphorus were analyzed at both stations between 2020 and 2021. The highest concentrations of contaminants were found in the rainy season, due to the washing away of the banks. In this sense, Cl presented a concentration more than 307 times higher than that permitted by Brazilian legislation (wet). The ecological index showed that the watershed has a high risk of metals such as Cr III and Cr VI for the biota. The human health risk analysis showed a low risk; however, the lack of basic sanitation in the city indicates that monitoring of urban water resources is necessary.

Stabilization of Chromium Waste by Solidification into Cement Composites

This article deals with the study of hazardous chromium leaching, stabilized/solidified by cement CEM II after 28 days of curing, in an acidic environment. The mortars subjected to this study were investigated by X-ray diffraction (XRD) characterization to evaluate the influence of chromium waste on their mineralogical structure. In the study range (0.6-1.2%), increasing the mass percentage of Cr2O3 in the mortars indicates that chromium accelerates the hydration process and setting of the mortar and increases the mechanical strength of the mortars compared to the control sample. It was observed that the release of chromium during the Toxicity Characteristic Leaching Procedure (TCLP) test and the efficiency of the stabilization/solidification process depended on the initial Cr concentration and the leaching time. The use of XRD allowed the identification of new crystallized phases in the cement matrices, namely, CaCrO4·2H2O and chromium-ettringite Ca6Cr2(SO4)3(OH)12·26H2O, which confirms the immobilization of chromium and the efficiency of the stabilization/solidification process. In this research, the release mechanism was found to be primarily a surface phenomenon by modeling the experimental data (dissolution or precipitation).

Enhanced detoxification of Cr6+ by Shewanella oneidensis via adsorption on spherical and flower-like manganese ferrite nanostructures

Maximizing the safe removal of hexavalent chromium (Cr6+) from waste streams is an increasing demand due to the environmental, economic and health benefits. The integrated adsorption and bio-reduction method can be applied for the elimination of the highly toxic Cr6+ and its detoxification. This work describes a synthetic method for achieving the best chemical composition of spherical and flower-like manganese ferrite (MnxFe3-xO4) nanostructures (NS) for Cr6+ adsorption. We selected NS with the highest adsorption performance to study its efficiency in the extracellular reduction of Cr6+ into a trivalent state (Cr3+) by Shewanella oneidensis (S. oneidensis) MR-1. MnxFe3-xO4 NS were prepared by a polyol solvothermal synthesis process. They were characterised by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometry (XPS), dynamic light scattering (DLS) and Fourier transform-infrared (FTIR) spectroscopy. The elemental composition of MnxFe3-xO4 was evaluated by inductively coupled plasma atomic emission spectroscopy. Our results reveal that the oxidation state of the manganese precursor significantly affects the Cr6+ adsorption efficiency of MnxFe3-xO4 NS. The best adsorption capacity for Cr6+ is 16.8 ± 1.6 mg Cr6+/g by the spherical Mn0.22+Fe2.83+O4 nanoparticles at pH 7, which is 1.4 times higher than that of Mn0.8Fe2.2O4 nanoflowers. This was attributed to the relative excess of divalent manganese in Mn0.22+Fe2.83+O4 based on our XPS analysis. The lethal concentration of Cr6+ for S. oneidensis MR-1 was 60 mg L-1 (determined by flow cytometry). The addition of Mn0.22+Fe2.83+O4 nanoparticles to S. oneidensis MR-1 enhanced the bio-reduction of Cr6+ 2.66 times compared to the presence of the bacteria alone. This work provides a cost-effective method for the removal of Cr6+ with a minimum amount of sludge production.

Landfill gas as a source of anthropogenic antimony and arsenic release

Antimony is used extensively in consumer goods, including single use plastic bottles, electronics, textiles and automobile brakes, which are disposed of in landfills at the end of their service lives. As a result, Sb is a constituent of concern in landfill emissions. Previous research has focused on leachate (liquid) and waste incineration flue gas emissions; however, Sb has the potential to volatilize through chemical and microbial processes within a landfill. In this study, iron-amended granular activated carbon was used to adsorb volatile metals directly from gas in a full-scale landfill gas collection system. Metals were quantified using acid digestion and ICP-AES analysis. Antimony concentrations far exceeded those previously reported, at up to 733 μg m^-3 (mean: 254 μg m^-3). In addition to Sb, As was also measured at high levels compared to previous research, as high as 740 μg m^-3 (mean: 178 μg m^-3). Using US EPA landfill and landfill gas databases, total Sb emissions via landfill gas are estimated to be approximately 27.3 kg day^-1 in the US. Based on other estimates of national and global Sb emissions, this corresponds to approximately 4.5% of total US atmospheric emissions of Sb and 0.42% of global atmospheric emissions. Sb mass release via landfill gas is approximately 3.9 times higher than via leachate emissions. Although gas emissions are higher than expected, the vast majority (99.9%) of Sb present in landfilled MSW remains within the waste mass indefinitely. In addition to these mass release estimates, this experiment suggests that iron-amended activated carbon may offer significant metals removal from LFG, especially in the first months of new well operation.

Biotic and Abiotic Biostimulation for the Reduction of Hexavalent Chromium in Contaminated Aquifers

Hexavalent chromium is a carcinogenic heavy metal that needs to be removed effectively from polluted aquifers in order to protect public health and the environment. This work aims to evaluate the reduction of Cr(VI) to Cr(III) in a contaminated aquifer through the stimulation of indigenous microbial communities with the addition of reductive agents. Soil-column experiments were conducted in the absence of oxygen and at hexavalent chromium (Cr(VI)) groundwater concentrations in the 1000–2000 μg/L range. Two carbon sources (molasses and EVO) and one iron electron donor (FeSO4·7H2O) were used as ways to stimulate the metabolism and proliferation of Cr(VI) reducing bacteria in-situ. The obtained results indicate that microbial anaerobic respiration and electron transfer can be fundamental to alleviate polluted groundwater from hazardous Cr(VI). The addition of organic electron donors increased significantly Cr(VI) reduction rates in comparison to natural soil attenuation rates. Furthermore, a combination of organic carbon and iron electron donors led to a longer life span of the remediation process and thus increased total Cr(VI) removal. This is the first study to investigate biotic and abiotic Cr(VI) removal by conducting experiments with natural soil and by applying biostimulation to modify the natural existing microbial communities.

Guilty by association: Assessment of environmental loadings on arsenic distribution in two Pacific Island rivers

This work evaluates the immediate risk of arsenic toxicity in two major river systems located in Western Viti Levu, Fiji and Guadalcanal, the Solomon Islands. Using principal component analysis, the associations between the major inorganic arsenic species, As (V) and As(III) and those of the controlling parameters, pH, dissolved oxygen and temperature were investigated in these aquatic systems. As(III) was found to be the dominant form of total inorganic As concentrations in five of the thirteen sites studied. There remains a high risk of As(III) exposure from these sites in the rivers. The study also examined the potential role of mine adits in influencing the distinct water chemistry at the sites. Over 50% of As was found to exist as the more toxic As(III) species at some sites (with higher levels near the gold mines) in both river systems. This finding implies that there may be health risk to populations relying on the river waters for agriculture. As(V) at most sites across both rivers exceeded 13 μg/L, defined as a trigger value for aquatic ecosystems by Australia and New Zealand standards. The PCA indicated that spatial variations play a significant role in water chemistries between sites further from the mine adit location in the Metapona River. In the Sabeto River system, there was also considerable intra-variability in the water chemistries between sites. Further detailed studies are necessary to determine a complete profile of As species and associated biogeochemical processes in these rivers which could lead on to identify appropriate containment or mitigation measures.

Molecular Mechanism of Arsenic-Induced Neurotoxicity including Neuronal Dysfunctions

Arsenic is a key environmental toxicant having significant impacts on human health. Millions of people in developing countries such as Bangladesh, Mexico, Taiwan, and India are affected by arsenic contamination through groundwater. Environmental contamination of arsenic leads to leads to various types of cancers, coronary and neurological ailments in human. There are several sources of arsenic exposure such as drinking water, diet, wood preservatives, smoking, air and cosmetics, while, drinking water is the most explored route. Inorganic arsenic exhibits higher levels of toxicity compared its organic forms. Exposure to inorganic arsenic is known to cause major neurological effects such as cytotoxicity, chromosomal aberration, damage to cellular DNA and genotoxicity. On the other hand, long-term exposure to arsenic may cause neurobehavioral effects in the juvenile stage, which may have detrimental effects in the later stages of life. Thus, it is important to understand the toxicology and underlying molecular mechanism of arsenic which will help to mitigate its detrimental effects. The present review focuses on the epidemiology, and the toxic mechanisms responsible for arsenic induced neurobehavioral diseases, including strategies for its management from water, community and household premises. The review also provides a critical analysis of epigenetic and transgenerational modifications, mitochondrial oxidative stress, molecular mechanisms of arsenic-induced oxidative stress, and neuronal dysfunction.

Environmental and Health Hazards of Chromated Copper Arsenate-Treated Wood: A Review

Copper chrome arsenate (CCA) water-borne solution used to be widely used to make timber highly resistant to pests and fungi, in particular, wood products designed for outdoor use. Nowadays, CCA is a restricted chemical product in most countries, since potential environmental and health risks were reported due to dermal contact with CCA residues from treated structures and the surrounding soil, as well as the contamination of soils. However, large quantities of CCA-treated timber are still in use in framings, outdoor playground equipment, landscaping, building poles, jetty piles, and fencing structures around the world, thus CCA remains a source of pollutants to the environment and of increasing toxic metal/metalloid exposure (mainly in children). International efforts have been dedicated to the treatment of materials impregnated with CCA, however not only does some reuse of CCA-treated timber still occur, but also existing structures are leaking the toxic compounds into the environment, with impacts on the environment and animal and human health. This study highlights CCA mechanisms and the documented consequences in vivo of its exposure, as well as the adverse environmental and health impacts.

Heavy metals in leachate, impacted soils and natural soils of different landfills in Malaysia: An alarming threat

Landfills are a potential threat to human health and the environment, especially from the detrimental and toxic heavy metals. This study focuses on the assessment of heavy metals contamination in leachate and surface soils from different landfills in Malaysia. Maximum quality rating scale (QRS) values of As (787) and Cr (552) denotes progressive deterioration of leachate contamination in landfill. The impacted soils showed high heavy metal concentrations especially at non-sanitary unlined landfills, as compared to background values, and natural soil nearby the landfills. In addition, to examine the environmental impacts of the landfill area (soil) in more detail, specific indexes; geo-accumulation index (Igeo), pollution index (PI) and integrated pollution index (IPI) were determined. Maximum As (3.122) and Cd (2.633) for Igeo and As (34.037) and Cd (20.881) for PI revealed that the soil samples in non-sanitary landfills were moderate to strongly polluted. The difference in range of IPI values for sanitary (0.294-0.322) and non-sanitary landfill soils (1.263-1.956) confirmed advanced decline of the soil quality in non-sanitary landfills. Arsenic concentrations were found to be statistically significant (ANOVA) for leachate and impacted soil in landfills investigated. It is also important to realize that rise in metal contents in landfill environments were not only caused by anthropogenic sources such as from the waste disposed, but also some other factors such as redox conditions, anoxic environments, pH, oxidation state of metals and microbial activities. Those conditions will actively promotes leaching of metals from waste and also natural soils in the landfill.

Microbial remediation for the removal of inorganic contaminants from treated wood: Recent trends and challenges

Owing to the seriousness of the ecological risk and human hazard of inorganic wood preservatives, their effective removal was gradually recognized. This paper details different types of wood preservatives, their perniciousness, and their potential removal alternatives, while the wood treatment process is briefly described. Among decontamination methods, microbial remediation is considered as an environmentally friendly approach with enormous potentialities over the conventional treatments. In the current review, the mechanism of bioremediation is summed up and recent advances, challenges, and future perspectives of microbial remediation are discussed. The removal of heavy metals from treated wood requires a combination of various technologies to obtain higher performance. Meanwhile, the decontaminated wood generated through bioremediation can be effectively reused.

Ionic Liquids as Antifungal Agents for Wood Preservation

Ionic liquids represent a class of highly versatile organic compounds used extensively in the last decade for lignocellulose biomass fractionation and dissolution, as well as property modifiers for wood materials. This review is dedicated to the use of ionic liquids as antifungal agents for wood preservation. Wood preservation against fungal attack represents a relatively new domain of application for ionic liquids, emerging in the late 1990s. Comparing to other application domains of ionic liquids, this particular one has been relatively little researched. Ionic liquids may be promising as wood preservatives due to their ability to swell wood, which translates into better penetration ability and fixation into the bulk of the wood material than other conventional antifungal agents, avoiding leaching over time. The antifungal character of ionic liquids depends on the nature of their alkyl-substituted cation, on the size and position of their substituents, and of their anion. It pertains to a large variety of wood-colonizing fungi, both Basidiomycetes and Fungiimperfecti.

Chromium Pollution in European Water, Sources, Health Risk, and Remediation Strategies: An Overview

Chromium is a potentially toxic metal occurring in water and groundwater as a result of natural and anthropogenic sources. Microbial interaction with mafic and ultramafic rocks together with geogenic processes release Cr (VI) in natural environment by chromite oxidation. Moreover, Cr (VI) pollution is largely related to several Cr (VI) industrial applications in the field of energy production, manufacturing of metals and chemicals, and subsequent waste and wastewater management. Chromium discharge in European Union (EU) waters is subjected to nationwide recommendations, which vary depending on the type of industry and receiving water body. Once in water, chromium mainly occurs in two oxidation states Cr (III) and Cr (VI) and related ion forms depending on pH values, redox potential, and presence of natural reducing agents. Public concerns with chromium are primarily related to hexavalent compounds owing to their toxic effects on humans, animals, plants, and microorganisms. Risks for human health range from skin irritation to DNA damages and cancer development, depending on dose, exposure level, and duration. Remediation strategies commonly used for Cr (VI) removal include physico-chemical and biological methods. This work critically presents their advantages and disadvantages, suggesting a site-specific and accurate evaluation for choosing the best available recovering technology.

Investigating arsenic impact of ACC treated timbers in compost production (A case study in Christchurch, New Zealand)

The arsenic concentration is an important issue in compost production. The main inputs of a compost factory, including kerbsides, green wastes, food industry wastes, and river weeds are investigated in this study. Also, this study investigated how treated timbers, ashes, and other contamination can impact arsenic concentration in compost production. The results showed that most treated timbers and all ashes of treated and untreated timbers contained significant amounts of arsenic. These results revealed that the presence of a small amount of treated timber ashes can significantly increase the arsenic concentration in composts. The results of the study show the arsenic concentration in compost increase during cold months, and it dropped during summer, which would be mostly because of high arsenic concentration in ashes of log burners. This study shows ashes of burning timbers can impact arsenic contamination mostly because of using Copper-Chrome-Arsenic wood preservatives (CCA). Also, the lab results show the arsenic level even in ashes of untreated timber is around 96 ppm. The ashes of H3, H4, and H5 treated timbers contain approximately 133,000, 155,000, and 179,000 ppm of arsenic, which one kg of them can increase arsenic concentration around 10 ppm in 13.3, 15.5 and 17.9 tons of dry compost products. The main problem is many people look at ashes and treated timber as organic materials; however, ashes of treated and untreated timbers contained high concentrations of arsenic. Therefore, it was necessary to warn people about the dangers of putting any ashes in organic waste bins.

Preparation of Lignin Nanoparticles with Entrapped Essential Oil as a Bio-Based Biocide Delivery System

Lignin isolated from beech sawdust was used for the preparation of lignin nanoparticles (LNPs) with entrapped essential oil (EO) from cinnamon bark (Cinnamomum zeylanicum Blume), common thyme (Thymus vulgaris L.), and wild thyme (Thymus serpyllum L.) using a fast antisolvent method. Analysis of EO-loaded LNPs by pyrolysis-gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy confirmed molecular interaction between EOs and LNPs. Quantification of EO incorporation into the LNPs and their in vitro release profiles were assessed by reversed phase high-performance liquid chromatography. Utilized EOs were, to different extents, successfully entrapped inside LNPs, which were attributed to extensive π-stacking between aromatic compounds in EOs like cinnamaldehyde, thymol, and carvacrol on one side and aromatic lignin units on the other side. In vitro release of common thyme and wild thyme EOs from EO-loaded LNPs was strongly delayed compared to the use of pure oil, giving a promising outlook for the development of new bio-based biocide delivery systems for wood preservation.

Comparative Cr, As and CCA induced Cytostaticity in mice kidney: A contribution to assess CCA toxicity

CCA (Chromium Copper Arsenate) treated wood, widely used in outdoor residential structures and playgrounds, poses considerable dangers of leaching of its components to the environment. In this study, mouse kidney samples were used to evaluate the effects of CCA, chromium trioxide (CrO₃) and arsenic pentoxide (As₂O₅) on cell pathophysiology by flow cytometry. Samples were collected after 14, 24, 48 and 96 h of animal exposure. While Cr had no statistically significant cytostatic effects, As₂O₅ induced a S-phase delay in animals exposed for 24 h, and over time a G0/G1 phase blockage. The effects of CCA in S-phase were similar, but more severe than those of As₂O₅. Since environmental and public health hazards due to the long durability of CCA-treated wood products, these data confirm that CCA has profoundly toxic effects on cell cycle, distinct from the compounds themselves. These cytostatic effects support cell cycle dynamics as a valuable endpoint to assess the toxicity of remaining CCA-treated infrastructures, and the expected increased waste stream over the coming decades.

Effects of sewage sludge biosolid amendments on the potential of maize (Zea mays L.) in phytoremediation of trace metals in chromated copper arsenate contaminated soils

The effect of sewage sludge amendment (5-25% w/w) on the potential of maize (MM3 variety) to phytoextract trace metals from chromated copper arsenate (CCA) contaminated soils was investigated. The metal content of fresh soils, and soils, maize roots and shoots after 80 days of planting were determined by atomic absorption spectroscopy. The concentrations of chromium, copper and arsenic in fresh CCA soils were 365.8 ± 6.18, 109.72 ± 14.04 and 28.22 ± 3.8 mg/kg respectively. The MM3 maize variety could be used to phytoextract or phytostabilize the trace metals in the CCA contaminated soils without or with 5-25% sewage sludge amendment.