Organic amendments temporarily change arsenic speciation and bioaccessibility in a lead and arsenic co-contaminated urban soil.

Organic amendments often reduce the bioaccessibility of soil lead (Pb) but not that of soil arsenic (As). The effect of Pb on As bioaccessibility is rarely studied in co-contaminated soils. In a field study, we assessed the effect of mushroom compost, leaf compost, noncomposted biosolids, and composted biosolids amendments on As speciation in a co-contaminated (As and Pb) soil at 7, 349, and 642 days after amending soils and the change of As speciation during an in vitro bioaccessibility extraction (gastric solution, pH 2.

Mobility of arsenic and vanadium in waterlogged calcareous soils due to addition of zeolite and manganese oxide amendments.

Addition of manganese(IV) oxides (MnO ) and zeolite can affect the mobility of As and V in soils due to geochemical changes that have not been studied well in calcareous, flooded soils. This study evaluated the mobility of As and V in flooded soils surface-amended with MnO or zeolite. A simulated summer flooding study was conducted for 8 weeks using intact soil columns from four calcareous soils.

Sustainable management of plastic wastes in COVID-19 pandemic: The biochar solution.

To prevent the COVID-19 transmission, personal protective equipment (PPE) and packaging materials have been extensively used but often managed inappropriately, generating huge amount of plastic waste. In this review, we comprehensively discussed the plastic products utilized and the types and amounts of plastic waste generated since the outbreak of COVID-19, and reviewed the potential treatments for these plastic wastes. Upcycling of plastic waste into biochar was addressed from the perspectives of both environmental protection and practical applications, which can be verified as promising materials for environmental protections and energy storages.

Phosphorus Release and Speciation in Manganese(IV) Oxide and Zeolite-Amended Flooded Soils.

Phosphorus (P) losses from flooded soils and subsequent transport to waterways contribute to eutrophication of surface waters. This study evaluated the effectiveness of MnO and a zeolite Y amendment in reducing P release from flooded soils and explored the underlying mechanisms controlling P release. Unamended and amended (MnO or zeolite, surface-amended at 5 Mg ha) soil monoliths from four clayey-alkaline soils were flooded at 22 ± 2 °C for 56 days.

Flooding-induced inorganic phosphorus transformations in two soils, with and without gypsum amendment.

Anaerobic conditions developed during flooding can increase phosphorus (P) losses from soils to waterways. Soil amendment with gypsum (CaSO ·2H O) can effectively reduce flooding-induced P release, but its effectiveness is soil dependent, and the reasons are poorly understood. The objectives of this study were to reveal the possible inorganic P transformations during flooding of two soils (acidic-Neuenberg sandy loam [NBG-SL] and alkaline-Fyala clay [FYL-Cl]), with and without gypsum amendment prior to flooding.

Sub-micron level investigation reveals the inaccessibility of stabilized carbon in soil microaggregates.

Direct evidence-based approaches are vital to evaluating newly proposed theories on the persistence of soil organic carbon and establishing the contributions of abiotic and biotic controls. Our primary goal was to directly identify the mechanisms of organic carbon stabilization in native-state, free soil microaggregates without disrupting the aggregate microstructure using scanning transmission x-ray microscopy coupled with near edge x-ray absorption fine structure spectroscopy (STXM-NEXAFS). The influence of soil management practices on microaggregate associated-carbon was also assessed.

Lead Speciation and In Vitro Bioaccessibility of Compost-Amended Urban Garden Soils.

In situ soil amendments can modify the Pb bioavailability by changing soil Pb speciation. Urban soils from three vegetable gardens containing different total Pb concentrations were used. The study evaluated how compost amendment and aging of soil-compost mixture in situ affected the following: (i) soil Pb speciation in the field and (ii) change of soil Pb speciation during an in vitro bioaccessibility extraction mimicking gastric phase dissolution at pH 2.

Potential bioavailability of lead, arsenic, and polycyclic aromatic hydrocarbons in compost-amended urban soils.

Urban soils may contain harmful concentrations of contaminants, such as lead (Pb), arsenic (As), and polycyclic aromatic hydrocarbons (PAHs), that can transfer from soil to humans via soil ingestion and consumption of food crops grown in such soils. The objective of this research was to assess the effectiveness of adding different compost types to reduce both direct (soil-human) and indirect (soil-plant-human) exposure of Pb, As, and PAHs to humans. A field experiment was conducted in 2011 and 2012 at an urban garden site with elevated concentrations of Pb (475 mg kg), As (95 mg kg), and PAHs (23-50 mg kg).

Field evaluations on soil plant transfer of lead from an urban garden soil.

Lead (Pb) is one of the most common contaminants in urban soils. Gardening in contaminated soils can result in Pb transfer from soil to humans through vegetable consumption and unintentional direct soil ingestion. A field experiment was conducted in 2009 and 2010 in a community urban garden with a soil total Pb concentration of 60 to 300 mg kg.