Nitrate in groundwater and agricultural products: intake and risk assessment in northeastern Iran.

The suitability of groundwater and agricultural products for human consumption requires determining levels and assessing the health risks associated with potential pollutants. Here, particularly pollution with nitrate still remains a challenge, especially for those urban areas suffering from insufficient sewage collection systems, resulting in contaminating soil, endangering food safety, and deteriorating drinking water quality. In the present study, nitrate concentrations in the commonly consumed fruit and vegetable species were determined, and the results, together with the groundwater nitrate levels, were used to assess the associated health risks for Mashhad city residents. For this assessment, 261 water samples and 16 produce types were used to compute the daily intake of nitrate. Nitrate in groundwater was analyzed using a spectrophotometer, and produce species were examined using High-Performance Liquid Chromatography. Ward's hierarchical cluster analysis was applied for categorizing produce samples with regard to their nitrate content. Additionally, to account for the sanitation hazards associated with groundwater quality for drinking purposes, total coliform and turbidity were also assessed using the membrane filter (MF) technique and a nephelometer, respectively. Nitrate concentrations exceeded the prescribed permissible limits in 42% of the groundwater wells. The outcomes also exhibit significantly higher nitrate accumulation levels in root-tuber vegetables and leafy vegetables compared to fruit vegetables and fruits. Using cluster analysis, the accumulation of nitrate in vegetables and fruits was categorized into four clusters, specifying that radish contributes to 65.8% of the total content of nitrate in all samples. The Estimated Daily Intake (EDI) of nitrate and Health Risk Index (HRI) associated with consumption of groundwater exceeded the prescribed limit for the children's target group in Mashhad's south and central parts. Likewise, EDI and HRI values for produce consumption, in most samples, were found to be in the tolerable range, except for radish, lettuce, and cabbage, potentially posing risks for both children and adult consumers. The total coliforms in groundwater were found to violate the prescribed limit at 78.93% of the sampling locations and were generally much higher over the city's central and southern areas. A relatively strong correlation (R2 = 0.6307) between total coliform and nitrate concentrations suggests the release of anthropogenic pollution (i.e., sewage and manure) in the central and southern Mashhad.

Small Hematite Nanoparticles from the Kiruna-Type Ore; Evaluation of Declined Balance Limit of the Attrition Process and Their Catalytic Properties.

Hematite nanoparticles possess unique properties which have motivated substantial attention for numerous applications, including environmental remediation and wastewater treatment as a promising novel technology. The magnetite-silicate raw material of Kiruna-type ore has been introduced as an innovative precursor, decreasing the attrition balance limit for large-scale production of the ball-mill-derived hematite nanoparticles below the critical size. In this study, the hypothesis and the postulated role of quartz in the effective size reduction process were further investigated. The prepared samples were characterized in detail via X-ray fluorescence (XRF) and powder X-ray diffractometry (pXRD) to be compared with the previous results. Furthermore, the catalytic and photocatalytic activities of the obtained nanoparticles were evaluated in the oxidation reaction of a common persistent sulfo-organic contaminant. The results exposed outstanding reactivity, particularly in their photocatalytic performance, suggesting them as a strong oxidizing agent and active photocatalyst, which greatly promises many possible applications including water and environmental remediation.

Kiruna-Type Ore as a Novel Precursor for Large-Scale Production of Small Uniform Iron Oxide Nanoparticles.

The wide range of actual and potential applications of nanoparticles, highlight the necessity of a reliable production method for both quality and quantity of the products. Mechanical attrition is one of the first well-known techniques used to produce nanoparticles. However, these approaches have been restricted to produce uniform particles below the critical size of 15 nm because of the attrition balance limit. This paper introduces the magnetite-silicate raw material of a Kiruna-type ore deposit as a novel precursor, which enables the production of small iron oxide nanoparticles below the critical size by mechanical attrition. X-ray fluorescence (XRF), powder X-ray diffractometry (pXRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used for characterization of the precursor and obtained nanoparticles. The results indicate that the particles with a mean diameter of 10.7(2.7) nm consist of mainly less than one crystallite. The significant size reduction below the attrition balance limit can be attributed to the quartz content of the raw material, which operated as supporting micro-balls for transferring the energy during the milling process.