Water scarcity poses a significant public health crisis exacerbated by climate change-induced disruptions to freshwater sources. Rainwater harvesting offers a sustainable solution by harnessing rooftop runoff for domestic use. This study analyzed 577 rooftop-harvested rainwater (RHRW) samples from four Arizona, USA environmental justice communities and 162 control samples from five National Atmospheric Deposition Program wet-only deposition collection sites across Arizona. The samples were tested for metal(loid)s, and the pollution load index (PLI) and Nemerow Integrated Pollution Index (NIPI) were used to assess contamination. The PLI was calculated for 11 known contaminants (As, Pb, Cd, Mn, Al, Cr, Cu, Zn, Ni, Ba, and Be), with the highest contamination factor observed for Ni (1340). PLI levels ranged from 0.118 to 65.8, with the active mining community Globe-Miami showing the highest range (0.244-65.8). The PLI was significantly greater during the monsoon season than during the winter season for all the communities (p < 0.05). Compared with urban communities (0.118-13.1), active mining communities (0.169-65.8) had higher PLI values. pH was positively correlated with PLI in Tucson (β = ln 0.27). In non-urban/rural mining communities, locations closer to potential contamination sources had higher PLI values (β = ln -0.33 to -0.38). However, in Tucson, the proximity relationship was less defined because of multiple potential contamination sources in urban areas. This study highlights the importance of using indices like PLI and NIPI to assess water quality; PLI reflects cumulative contamination burden, while NIPI contextualizes this burden within potential water uses. The strong positive correlation observed between PLI and NIPI across all use categories supports the validity of both indices and affirms utility. Together, they provide a nuanced understanding of pollution dynamics in RHRW and strengthen the case for public health interventions and ensuring the safety and sustainability of RHRW.

People facing pollution do not always have the resources needed to investigate their environment for harmful contaminants. In this paper, we report on a low-cost, accessible method to screen soil for inorganic arsenic, a substance associated with a growing list of acute and chronic diseases. The method adapts a commercial water test kit, which measures inorganic arsenic between 0 and 500 µg L−1 on a quantitative, discrete color scale. We evaluated two extraction solutions in determining bioaccessible and total inorganic arsenic. We characterized soil samples and standards containing total arsenic between 0.8 and 3240 mg kg−1 (n = 151) with the screening methodology and established laboratory methods. While the total screening method requires additional investigation, we propose the bioaccessible screening method for two purposes. First, it estimates in vitro bioaccessible assay (IVBA) arsenic ( y=0.0972x , R^2=0.576 ) to provide physiological insight. Second, it estimates a predicted minimum amount of total arsenic to compare to regulatory soil levels. Screening measurements above 82.5 and 132.0 µg L−1 are predicted to exceed the Arizona Department of Environmental Quality (AZDEQ) and New York Department of Environmental Conservation (NYDEC) regulatory soil levels: 10 and 16 mg kg−1, respectively. False positives are almost entirely avoided, while the occurrence of false negatives increases approaching the predicted thresholds. Screening measurements in the ranges [0, 10), [10, 25), and [25, threshold] µg L−1 were false negatives (false omission rate) 0, 18.8, and 81.4

Insensitive high-explosive compounds like 3-nitro-1,2,4-triazol-5-one (NTO) can contaminate soil and water at military sites. This study compared the ability of synthesized and commercial MnO2 materials to degrade the reduced daughter product of NTO, 3-amino-1,2,4-triazol-5-one (ATO), and characterized the solid-phase transformations that govern the products formed in continuousflow reactors. Synthetic birnessite degraded ATO fastest (k = 15.0 h- 1) but had poor hydraulic characteristics. Whereas the commercial material Pro-OXTM had a good degradation rate (k = 0.64 h- 1) and its granular morphology ensured good hydraulic performance. Results show ATO is oxidized by MnO2-type minerals to benign end-products (urea, NH4+, CO2(g), and N2(g)). Spent Mn oxides were fully regenerated using KMnO4 or NaOCl, restoring or even surpassing their original oxidative capacity. Further investigation of Pro-OX in packed-bed columns under a simulated wastewater treatment regime (1 mM ATO, empty bed contact time [EBCT]= 1 h) showed that the column reached breakthrough (C/C0 >= 0.05) at 2400 pore volumes (PVs), with a capacity to degrade 190 mg ATO g- 1. Under accelerated groundwater flow regime (0.1 mM ATO, EBCT= 24 h), the reactor removed ATO effectively for the duration of operation (660 PVs). After reacting with ATO, the Mn oxide material initially dominated by Mn(IV) (e.g., pyrolusite, ramsdellite, todorokite) was converted to Mn(III) minerals (e.g., groutite, manganite) and soluble Mn(II) (recovered in effluent) indicating reduction of MnO2 concurrent with ATO oxidation. Collectively, these findings demonstrate that MnO2 is a promising material for application in permeable reactive barriers or packed-bed filters to treat waters contaminated with ATO at military sites.

The insensitive munitions compound nitroguanidine (NQ) is used by the U.S. Army to avoid unintended explosions. However, NQ also represents an emerging contaminant whose environmental emissions can cause toxicity toward aquatic organisms, indicating the need for effective remediation strategies. Thus, we investigated the feasibility of treating water contaminated with NQ in continuous-flow columns packed with zero-valent iron (ZVI) or iron sulfide (FeS). Initially, the impact of pH on NQ transformation by ZVI or FeS was evaluated in batch experiments. The pseudo first-order rate constant for NQ transformation (k1, NQ) by ZVI was 8–10 times higher at pH 3.0 compared to pH 5.5 and 7.0, whereas similar k1, NQ values were obtained for FeS at pH 5.5–10.0. Based on these findings, the influent pH fed to the ZVI- and FeS-packed columns was adjusted to 3.0 and 5.5, respectively. Both reactors transformed NQ into nitrosoguanidine (NsoQ). Further transformation of NsoQ by ZVI produced aminoguanidine, guanidine, and cyanamide, whereas NsoQ transformation by FeS produced guanidine, ammonium, and traces of urea. ZVI outperformed FeS as a reactive material to remove NQ. The ZVI-packed column effectively removed NQ below detection even after 45 d of operation (490 pore volumes, PV). In contrast, NQ breakthrough (removal efficiency <85%) was observed after 18 d (180 PV) in the FeS-packed column. The high NQ removal efficiency and long service life of the ZVI-packed column (>490 PV) suggest that the technology is a promising approach for NQ treatment in packed-bed reactors and in situ remediation.

Plant species inhabiting industrial areas have evolved resilience in stressed environments and represent potential valuable resources for remediating polluted sites. However, data describing the potential of xeric plant species in sustainable green applications remain scarce. This study aims to evaluate the effectiveness of mycorrhiza-amended xeric plant species Lygeum spartum, in coping with arid conditions for phytoremediation and ecological restoration of degraded and contaminated lands. A six-month controlled pot experiment was conducted to assess leaf length, enzymatic activities, and secondary metabolites. Toxic metals and metalloids (TMMs) fate was evaluated using translocation factor (TF), bioaccumulation factor (BF) and removal efficiency (RE). Fungal inoculation positively impacted growth, increasing leaf size by 64.6 % and enhancing chlorophyll content - Chl a (0.73 mg g-1 DW) and Chl b (0.64 mg g-1 DW). Root uptake of Cd, Ni, Zn, Cu, Co, Cr and Pb was significantly enhanced in mycorrhizal plants (p < 0.05), and inoculation improved translocation of Zn, Cr and Co, with TFZn = 1.67, TFCr = 1.11 and TFCo = 1.05 respectively. Secondary metabolites included flavonoids, total phenols, glutathion-S-transferase, carotenoids, and antioxidants such as peroxidase (POD, 4.25 μmol min-1 mg-1 proteins), ascorbate peroxidase (APX, 2.14 μmol min-1 mg-1 proteins) and superoxide dismutase (SOD, 17.04 66 U mg-1 protein). However, no improvement was observed in catalase activity or free radical scavenging potential. Therefore, xeric plant species amended with mycorrhiza are effective in TMM phytoremediation in arid environments and can be used for the restoration of degraded lands. Further, mycorrhiza could be used as sink cultures for the Phyto management and sustainable eco-restoration.

The widespread presence of per- and polyfluoroalkyl substances (PFAS) in the environment, driven by extensive industrial use, has raised global concerns due to their persistence and adverse health effects. Despite the increased regulatory focus on a sub-set of well-known PFAS, over 12,000 compounds exist, many poorly characterized. Our study assessed hidden PFAS concentrations, undetectable by standard LC-MS/MS analysis, in contaminated groundwater. We analyzed total oxidizable precursors (TOP) via TOP assay followed by LC-MS/MS, and total organic fluorine (TOF) via combustion ion chromatography (CIC). Results were compared with those from LC-MS/MS analysis of 25 individual PFAS (∑PFAS25), representing the non-hidden PFAS fraction. We also evaluated the removal of hidden PFAS employing conventional and novel adsorbents. Groundwater samples from drinking water sources and contaminated military sites in the USA showed varying PFAS contamination levels as indicated by TOF values ranging from non-detect (<0.7 μg L−1) to 40.2 μg L−1. ∑PFAS25 was a major fraction of the TOF (41.7 − 92.8%) in some samples, whereas in others it only accounted for 5.1 − 20.4% of the TOF. The remaining percentages consisted of hidden PFAS not detected by conventional LC-MS/MS, but detectable as TOF by CIC. Organic fluorine content of oxidizable precursors accounted for 0.0–39.0% of TOF content, depending on the sample. Selected samples underwent adsorption with activated carbon (AC), anion exchange resin (IX), polyaniline (PANI), and poly-o-toluidine (POT). All adsorbents removed the hidden PFAS less effectively than the PFAS quantified by direct LC-MS/MS techniques. This is likely because PFAS adsorbents investigated to date primarily target anionic per- and polyfluoroalkyl acids, not effectively removing cationic, neutral, or zwitterionic hidden PFAS. AC exhibited the best overall performance among the investigated adsorbents. The results demonstrate that measuring TOP and TOF concentrations is effective for evaluating the removal of hidden PFAS in groundwater remediation.

Cadmium (Cd) and arsenic (As) co-contamination is widespread and threatens human health, therefore it is important to investigate the bioavailability of Cd and As co-exposure. Currently, the interactions of Cd and As by in vitro assays are unknown. In this work, we studied the concurrent Cd-As release behaviors and interactions with in vitro simulated gastric bio-fluid assays. The studies demonstrated that As bioaccessibility (2.04 to 0.18 +/- 0.03%) decreased with Cd addition compared to the As(V) single system, while Cd bioaccessibility (11.02 to 39.08 +/- 1.91%) increased with As addition compared to the Cd single system. Release of Cd and As is coupled to proton-promoted and reductive dissolution of ferrihydrite. The As(V) is released and reduced to As(V) by pepsin. Pepsin formed soluble complexes with Cd and As. X-ray photoelectron spectroscopy showed that Cd and As formed Fe-As-Cd ternary complexes on ferrihydrite surfaces. The coordination intensity of As-O-Cd is lower than that of As-O-Fe, resulting in more Cd release from Fe-As-Cd ternary complexes. Our study deepens the understanding of health risks from Cd and As interactions during environmental co-exposure of multiple metal(loid)s.

Arsenic (As) mobilization in paddy fields poses significant health risks, necessitating a thorough understanding of the controlling factors and mechanisms to safeguard human health. We conducted a comprehensive investigation of the soil-porewater-rice system throughout the rice life cycle, focusing on monitoring arsenic distribution and porewater characteristics in typical paddy field plots. Soil pH ranged from 4.79 to 7.98, while porewater pH was weakly alkaline, varying from 7.2 to 7.47. Total arsenic content in paddy soils ranged from 6.8 to 17.2mg/kg, with arsenic concentrations in porewater during rice growth ranging from 2.97 to 14.85μg/L. Specifically, arsenite concentrations in porewater ranged from 0.48 to 7.91μg/L, and arsenate concentrations ranged from 0.73 to 5.83μg/L. Through principal component analysis (PCA) and analysis of redox factors, we identified that arsenic concentration in porewater is predominantly influenced by the interplay of reduction and desorption processes, contributing 43.5% collectively. Specifically, the reductive dissolution of iron oxides associated with organic carbon accounted for 23.3% of arsenic concentration dynamics in porewater. Additionally, arsenic release from the soil followed a sequence starting with nitrate reduction, followed by ferric ion reduction, and subsequently sulfate reduction. Our findings provide valuable insights into the mechanisms governing arsenic mobilization within the paddy soil-porewater-rice system. These insights could inform strategies for irrigation management aimed at mitigating arsenic toxicity and associated health risks.

The sulfur chemistry of (162173) Ryugu particles can be a powerful tracer of molecular cloud chemistry and small body processes, but it has not been well explored. We report identification of organosulfurs and a sulfate grain in two Ryugu particles, A0070 and A0093. The sulfate grain shows oxygen isotope ratios (δ 17 O = −11.0 ± 4.3 per mil, δ 18 O = −7.8 ± 2.3 per mil) that are akin to silicates in Ryugu but exhibit mass-independent sulfur isotopic fractionation (Δ 33 S = +5 ± 2 per mil). A methionine-like coating on the sulfate grain is isotopically anomalous (δ 15 N = +62 ± 2 per mil). Both the sulfate and organosulfurs can simultaneously form and survive during aqueous alteration within Ryugu’s parent body, under reduced conditions, low temperature, and a pH >7 in the presence of N-rich organic molecules. This work extends the heliocentric zone where anomalous sulfur, formed by selective photodissociation of H 2 S gas in the molecular cloud, is found.

The need for effective technologies to remediate the insensitive munitions compound 3-nitro-1,2,4-triazol-5-one (NTO) is emerging due to the increasing use by the US Army and environmental concerns about the toxicity and aqueous mobility of NTO. Reductive treatment is essential for the complete degradation of NTO to environmentally safe products. The objective of this study is to investigate the feasibility of applying zero-valent iron (ZVI) in a continuous-flow packed bed reactor as an effective NTO remediation technology. The ZVI-packed columns treated an acidic influent (pH 3.0) or a circumneutral influent (pH 6.0) for 6 months (ca. 11,000 pore volumes, PVs). Both columns effectively reduced NTO to the amine product, 3-amino-1,2,4-triazol-5-one (ATO). The column treating the pH-3.0 influent exhibited prolonged longevity in reducing NTO, treating 11-fold more PVs than the column treating pH-6.0 influent until the breakthrough point (defined as when 85% of NTO was removed). The exhausted columns (defined as when only 10% of NTO was removed) regained the NTO reducing capacity by reactivation using 1 M HCl, fully removing NTO. After the experiment, solid-phase analysis of the packed-bed material showed that ZVI was oxidized to iron (oxyhydr)oxide minerals such as magnetite, lepidocrocite, and goethite during NTO treatment. This is the first report on the reduction of NTO and the concomitant oxidation of ZVI in continuous-flow column experiments. The evidence indicates that treatment in a ZVI-packed bed reactor is an effective approach for the removal of NTO.

The military is switching over to insensitive munitions compounds (IMCs) to avoid unintentional detonations during handling and use of explosives. 3-nitro-1,2,4-triazol-5-one (NTO) is an important component of IMCs. NTO may contaminate the subsurface due to its high aqueous solubility. Thus, there is a need to develop remediation technologies for the treatment of NTO-containing (waste) water. This study demonstrated that zero-valent iron (ZVI) reductively transformed NTO to its daughter product, 3-amino-1,2,4-triazol-5-one. The pseudo first-rate constant (k1) of NTO reduction by micron-sized ZVI at pH 3 was 192.6 h−1. Kinetic degradation experiments performed at different pH values showed that ZVI did not effectively reduce NTO at pH 6 (k1 = 0.6 h−1) or higher. The rapid NTO reduction in acidic conditions may be due to dissolution of iron precipitates on the ZVI surface. Additional experiments were conducted to assess the effectiveness of various depassivating pretreatments with deionized water, acetic acid, hydrochloric acid, or bicarbonate. Treatment with 1 M HCl for 15 min was the most effective depassivation method for a ZVI material containing a thick passivating layer (ca. 880 nm), achieving 84.0

Inadvertent oral ingestion is an important exposure pathway of arsenic (As) containing soil and dust. Previous researches evidenced health risk of bioaccessible As from soil and dust, but it is unclear about As mobilization mechanisms in health implications from As exposure. In this study, we investigated As release behaviors and the solid-liquid interface reactions toward As(V)-containing iron minerals in simulated gastrointestinal bio-fluids. The maximum As release amount was 0.57 mg/L from As-containing goethite and 0.82 mg/L from As-containing hematite at 9 h, and the As bioaccessibility was 10.8% and 21.6%, respectively. The higher exposure risk from hematite-sorbed As in gastrointestinal fluid was found even though goethite initially contained more arsenate than hematite. Mechanism analysis revealed that As release was mainly coupled with acid dissolution and reductive dissolution of iron minerals. Proteases enhanced As mobilization and thus increased As bioaccessibility. The As(V) released and simultaneously transformed to high toxic As(III) by gastric pepsin, while As(V) reduction in intestine was triggered by pancreatin and freshly formed Fe(II) in gastric digests. CaCl2 reduced As bioaccessibility, indicating that calcium-rich food or drugs may be effective dietary strategies to reduce As toxicity. The results deepened our understanding of the As release mechanisms associated with iron minerals in the simulated gastrointestinal tract and supplied a dietary strategy to alleviate the health risk of incidental As intake.

Here, we detail arsenic (As) and lead (Pb) concentrations in community science generated rooftop harvested rainwater data from Project Harvest (PH), a co-created community science study, and National Atmospheric Deposition Program (NADP) National Trends Network wet-deposition AZ samples as analyzed by Palawat et al. [1]. 577 field samples were collected in PH and 78 field samples were collected by NADP. All samples were analyzed via inductively coupled plasma mass spectrometry (ICP-MS) for dissolved metal(loid)s including As and Pb by the Arizona Laboratory for Emerging Contaminants after 0.45 um filtration and acidification. Method limits of detection (MLOD) were assessed and sample concentrations above MLODs were considered detects. Summary statistics and box and whisker plots were generated to assess variables of interest such as community and sampling window. Finally, As and Pb data is provided for potential reuse; the data can be used to assess contamination of harvested rainwater in AZ and to inform community use of natural resources.

As climate change exacerbates water scarcity, rainwater harvesting for household irrigation and gardening becomes an increasingly common practice. However, the use and quality of harvested rainwater are not well studied, and the potential pollutant exposures associated with its use are generally unknown. There are currently no federal standards in the United States to assess metal(loid)s in harvested rainwater. Project Harvest, a community science research project, was created to address this knowledge gap and study the quality of harvested rainwater, primarily used for irrigation, in four environmental justice communities in Arizona, USA. Community scientists collected 577 unique rooftop harvested rainwater samples from 2017 to 2020, which were analyzed for metal(loid)s, where arsenic (As) concentrations ranged from 0.108 to 120 μg L-1 and lead (Pb) concentrations ranged from 0.013 to 350 μg L-1 and compared to relevant federal/state standards/recommendations. Community As and Pb concentrations decreased as: Hayden/Winkelman > Tucson > Globe/Miami > Dewey-Humboldt. Linear mixed models were used to analyze rooftop harvested rainwater data and results indicated that concentrations of As and Pb in the summer monsoon were significantly greater than winter; and contamination was significantly greater closer to extractive industrial sites in three of the four study communities (ASARCO Hayden Plant Superfund Alternative site in Hayden/Winkelman, Davis-Monthan United States Air Force Base in Tucson - Pb only, and Freeport McMoRan Copper and Gold Mine in Globe/Miami). Based on models, infrastructure such as proximity to roadway, roof material, presence of a cistern screen, and first-flush systems were not significant with respect to As and Pb when controlling for relevant spatiotemporal variables; whereas, cistern age was associated with Pb concentrations. These results however, indicate that concentrations vary seasonally and by proximity to industrial activity, not by decisions made regarding collection system infrastructures at the individual home level. This study shows that generally, individuals are not responsible for environmental contamination of rooftop harvested rainwater, rather activities and decisions of government and corporate industries control contaminant release.