Fractionation and mechanism of Fe in the mineral-associated soil fraction from the Mongolian Plateau grasslands.

The Mongolian Plateau grasslands constitute a vital ecological barrier in inland Asia. Within these ecosystems, the mineral-associated soil fraction (<53 μm, MASF) is the dominant component, and its iron (Fe) oxides play a pivotal role in mediating carbon (C), nitrogen (N), and phosphorus (P) cycling. Using sequential chemical extraction, we quantified seven Fe fractions (Fe, Fe, Fe, Fe, Fe, Fe, and Fe) within the MASF across the plateau.

Breaking the Carbon-Fluorine Stronghold: Reductive Defluorination of PFASs.

Per/polyfluoroalkyl substances (PFASs), characterized by their ultrastable C-F bonds and pervasive environmental persistence, present critical remediation challenges due to their recalcitrance and bioaccumulative potential. Conventional oxidative degradation methods predominantly yield bioaccumulative short-chain fluorinated derivatives, failing to achieve molecular annihilation. We highlight reductive defluorination as a transformative strategy to directly cleave C-F bonds and mitigate toxicity through two distinct electron-transfer modalities: indirect routes mediated by reactive species (e.

Interface processes of endogenous phosphorus during the freeze period: The driving role of iron dissimilation reduction and the unignorable organic phosphorus release.

Iron redox cycling governs the early diagenesis of organic matter (OM) and significantly influences phosphorus (P) dynamics in aquatic systems. The release of endogenous P during freezing periods carries significant ecological implications for these systems. However, it remains unclear whether microbial dissimilatory iron reduction maintains a dominant role under anoxic freezing conditions, and the potential impact of weakened microbial-mediated P release via this pathway has not been adequately addressed.

Effects of Oxygenation Resuspension on DOM Composition and Its Role in Reducing Dissolved Manganese in Drinking Water Reservoirs.

Anaerobic conditions in source water sediments are a key driver of manganese (Mn) release in drinking water systems. Enhancing sediment oxidation can inhibit Mn release, but the mechanisms of Mn speciation under varying oxidative conditions remain unclear. This study examined sediment exposure to oxygenated water layers at controlled dissolved oxygen levels (0, 2, 5, 7 mg L) through laboratory simulations.

Adsorption of As(III) to schwertmannite: impact factors and phase transformation.

The phase transformation of Schwertmannite (SCH) can significantly affect the interface behavior and toxic effect of As(III). Previous studies have predominantly focused on pollutants adsorption by SCH on a long-time scale (such as 30 days), without paying attention to the adsorption characteristics within shorter time frames (e.g.

Crouching bacteria, hidden tetA genes in natural waters: Intracellular damage via double persulfate activation (UVA/Fe/PDS) effectively alleviates the spread of antibiotic resistance.

In this study, we elucidated the chemical and biological inactivation mechanisms of peroxydisulfate (PDS) activated by UVA and Fe (UVA/Fe/PDS) in wild-type antibiotic-resistant bacteria (ARB) isolated from a river in Inner Mongolia. Among the screened wild-type ARB, the relative abundance of unidentified Enterobacteriaceae, Stenotrophomonas, and Ralstonia was high. A ratio of 1:1 for Fe and PDS under 18 W·m UVA radiation (sunny days) completely inactivated the environmental ARB isolates.

Evolution of hydrochemical characteristics and the influence of environmental background in the Hailar River basin, China.

Understanding the evolution of hydrochemical characteristics in river systems is essential for environmental assessment and water resource management. This study explores the spatiotemporal distribution and the determinants of hydrochemical characteristics in the Hailar River basin, China, over an extensive period. Our results revealed that COD and COD were the primary concerns for long-term river management, with exceedance rates of 42.

Reductive dissolution of As-bearing iron oxides: Mediating mechanism of fulvic acid and dissimilated iron reducing bacteria.

Fulvic acid (FA) and iron oxides often play regulating roles in the geochemical behavior and ecological risk of arsenic (As) in terrestrial ecosystems. FA can act as electron shuttles to facilitate the reductive dissolution of As-bearing iron (hydr)oxides. However, the influence of FA from different sources on the sequential conversion of Fe/As in As-bearing iron oxides under biotic and abiotic conditions remains unclear.

Zero-valent iron (ZVI) facilitated in-situ selenium (Se) immobilization and its recovery by magnetic separation: Mechanisms and implications for microbial ecology.

Selenium (Se(VI)) is environmentally toxic. One of the most popular reducing agents for Se(VI) remediation is zero-valent iron (ZVI). However, most ZVI studies were carried out in water matrices, and the recovery of reduced Se has not been investigated.

The fate of Arsenic associated with the transformation of iron oxides in soils: The mineralogical evidence.

The influence of iron (oxyhydr)oxides on the transformation and migration of arsenic(As) has garnered significant attention. Previous work has largely focused on the transformation of iron oxides related to As fate at molecular and mechanistic levels. However, studies examining the interplay between As concentration and iron oxides transformation within complex soil system are sparse.

Water-soluble brown carbon in atmospheric aerosols from the resource-dependent cities: Optical properties, chemical compositions and sources.

As a vital type of light-absorbing aerosol, brown carbon (BrC) presents inherent associations with atmospheric photochemistry and climate change. However, the understanding of the chemical and optical properties of BrC is limited, especially in some resource-dependent cities with long heating periods in northwest China. This study showed that the annual average abundances of Water-soluble BrC (WS-BrC) were 9.

Significant methane ebullition from large shallow eutrophic lakes of the semi-arid region of northern China.

Eutrophic lakes are a major source of the atmospheric greenhouse gas methane (CH), and CH ebullition emissions from inland lakes have important implications for the carbon cycle. However, the spatio-temporal heterogeneity of CH ebullition emission and its influencing factors in shallow eutrophic lakes of arid and semi-arid regions remain unclear. This study aimed to determine the mechanism of CH emission via eutrophication in Lake Ulansuhai, a large shallow eutrophic lake in a semi-arid region of China.

Geochemical characteristics and socioeconomic associations of carbonaceous aerosols in coal-fueled cities with significant seasonal pollution pattern.

Carbonaceous aerosols, comprising organic carbon (OC) and elemental carbon (EC), are critical component of fine particulate matter (PM), with diverse impacts on air quality and human health. This study investigated the concentrations and seasonal patterns of carbonaceous species in PM during both the heating season (January 2021) and non-heating season (July 2021) in three coal-fueled cities in northern China, as well as the differences in carbonaceous aerosols and their associations with socioeconomic parameters in cities situated on either side of the "Hu Line" in China. The results showed that, owing to intensified coal combustion and unfavorable meteorological conditions, levels of OC, EC, and OC/EC ratios were higher in winter compared to summer.

Fluxes in CO and CH and influencing factors at the sediment-water interface in a eutrophic saline lake.

Although saline aquatic ecosystems are significant emitters of greenhouse gases (GHGs), dynamic changes in GHGs at the sediment-water interface remain unclear. The present investigation carried out a total of four sampling campaigns in Daihai Lake, which is a eutrophic saline lake situated in a semi-arid area of northern China. The aim of this study was to investigate the spatio-temporal dynamics of carbon dioxide (CO) and methane (CH) fluxes at the sediment-water interface and the influencing factors.

A new method based on additive vegetation index for mapping Huangtai algae coverage in Lake Ulansuhai.

Huangtai algal blooms are key indicators of eutrophication and lake-ecosystem damage. Understanding the spatiotemporal heterogeneity of their growth is critical for preserving the ecological environment. The dimidiate pixel model is commonly used to estimate vegetation coverage; however, indices such as the normalized difference vegetation index have not been specifically constructed for the Huangtai algae spectrum and thus are not specific or sufficiently precise for use as indicators.

Drivers of spatial and seasonal variations of CO and CH fluxes at the sediment water interface in a shallow eutrophic lake.

Shallow eutrophic lakes contribute disproportional to the emissions of CO and CH from inland waters. The processes that contribute to these fluxes, their environmental controls, and anthropogenic influences, however, are poorly constrained. Here, we studied the spatial variability and seasonal dynamics of CO and CH fluxes across the sediment-water interface, and their relationships to porewater nutrient concentrations in Lake Ulansuhai, a shallow eutrophic lake located in a semi-arid region in Northern China.

Arthroscopic reconstruction of anterior cruciate ligaments with allograft: single-tunnel single-bundle versus single-tunnel double-bundle techniques.

Purpose: To compare the clinical results of anterior cruciate ligament (ACL) reconstruction using the single-tunnel single-bundle (STSB) technique versus the single-tunnel double-bundle (STDB) technique.

Methods: This was a retrospective, single-center, single-surgeon study based on data collected from March 2012 to June 2013. According to our inclusion/exclusion criteria, a total of 78 patients (64 males, 14 females; mean age, 25.

Arsenic speciation transformation in soils with high geological background: New insights from the governing role of Fe.

In soils, the speciation transformation of As were inherently related to the behaviors of iron (oxyhydr) oxides. It is poorly understood that the effects of the transformation of iron (oxyhydr) oxides coupled with As speciation transformation during dissimilatory Fe(III) reduction (DIR) involving with humic substances (HS) as electron donor or shuttle in soils with high arsenic geological background. In this study, the relationships between the transformation of iron (oxyhydr)oxides and As speciation transformation were investigated according to the response between continuously As speciation monitoring and iron (oxyhydr) oxides identification during DIR in the soils.

Changes in stoichiometric characteristics of ambient air pollutants pre-to post-COVID-19 in China.

To prevent the Corona Virus Disease 2019 (COVID-19) spreading, Chinese government takes a series of corresponding measures to restrict human mobility, including transportation lock-down and industries suspension, which significantly influenced the ambient air quality and provided vary rare time windows to assess the impacts of anthropological activities on air pollution. In this work, we divided the studied timeframe (2019/12/24-2020/2/24) into four periods and selected 88 cities from 31 representative urban agglomerations. The indicators of PM/PM and NO/SO were applied, for the first time, to analyze the changes in stoichiometric characteristics of ambient air pollutants pre-to post-COVID-19 in China.

Trends and environmental factors of arsenic in sediments from the five lake ecoregions, China.

The behavior and risk of arsenic (As) closely relate to its geochemical fractionation and environmental factors in sediments. The soluble (F1), reducible (F2), oxidizable (F3), and residual fraction (F4) of As were extracted in the sediments from Lake Hulun, Wuliangsuhai, and Dalinor of Inner Mongolia Plateau. Coupled with lakes from Eastern and Northeast Plain, Yunnan-Guizhou and Qinghai-Tibetan Plateau, the responses of As fractions to environmental conditions were investigated according to the spatial distribution of As fractionations in five lake ecoregions at a national scale of China.

Heating events drive the seasonal patterns of volatile organic compounds in a typical semi-arid city.

The emission characteristics, source apportionment and chemical behavior of volatile organic compounds (VOCs) are important for strategy-making on ozone (O) and fine particulate matter (PM) control. Based on the continuous observation during four seasons, the seasonal characteristics, chemical reactivity and source apportionment of 116 VOCs species were studied in a typical semi-arid city with no relevant research. The results showed that the annual average concentrations of total volatile organic compounds (TVOCs) in Hohhot was 44.

Factors and pathways regulating the release and transformation of arsenic mediated by reduction processes of dissimilated iron and sulfate.

The driving process and explanatory factors regulating the transformation and migration of arsenic (As) mediated by dissimilatory iron reducing bacteria (DFeRB) and sulfate reducing bacteria (SRB) remain poorly understood. The novelty of this study is to explore the driving process and key environmental factors governing As mobilization mediated by DFeRB and SRB based on continuous As speciation and environmental parameter monitoring in a sediment-water system. The results illustrate the reduction process mediated by DFeRB and SRB significantly promotes the reduction of As(V) and the endogenous release of As.

Distribution, sources, and ecological risk assessment of polycyclic aromatic hydrocarbons in the sediments of Daihai Lake in Inner Mongolia, China.

Polycyclic aromatic hydrocarbons (PAHs) are typical toxic organic pollutants that can accumulate in sediments and may be toxic to aquatic organisms. In the present study, the contamination level, composition pattern, and sources of sixteen PAHs listed by the United States Environmental Protection Agency were investigated in surface sediments and a sediment core from Daihai Lake, which is located in a typical semiarid area of Inner Mongolia, China, and the ecological risk of these PAHs was assessed. The results show that the total concentration of PAHs in the surface sediments ranged from 204.