Community pattern of potential phenanthrene (PHE) degrading bacteria in PHE contaminated soil revealed by 13C-DNA stable isotope probing.

Quantification of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil and identification of potential PAH degraders are essential for comprehending their environmental fate and conducting bioremediation. However, the microbial population responsible for the breakdown of phenanthrene (PHE) in polluted soil environments is frequently disregarded. In this study, via DNA-stable-isotope probing (DNA-SIP), we found that soil microbiota likely plays a crucial part in the PHE degradation. The PHE removal rates were 98% and 99%, in 13C-PHE and 12C-PHE microcosmic incubations, respectively. 13CO2 was produced along with the degradation of 13C-PHE. According to the analysis of 16S rRNA gene, there was a relatively higher presence of unidentified bacteria in the 'heavy' DNA fractions treated with 13C-PHE. Genus of Enterobacteriales, Acidobacteria, Alphaproteobacteria, Paenibacillaceae, Flavobacteriia, Chloroflexi, Cyanobacteria, Caldilineae, Latescibacteria, Armatimonadetes and Blastocatellia were succseesfully labeled during the degradation of 13C-PHE, indicating their capacity of utilizing PHE. Co-occurrence network of 13C-heavy fractions exhibited greater complexity compared with that of 12C-heavy fractions, revealling an enhancement of bacterial interspecies interactions. Collectivley, this study eluidated the soil microbes involed in the PHE degradation and offered fresh perspectives on the community pattern of potential PHE degrading bacteria.

Ubiquity of Amino Accelerators and Antioxidants in Road Dust from Multiple Land Types: Targeted and Nontargeted Analysis.

Amino accelerators and antioxidants (AAL/Os), as well as their degradation derivatives, are industrial additives of emerging concern due to their massive production and use (particularly in rubber tires), pervasiveness in the environment, and documented adverse effects. This study delineated their inter-regional variations in road dust collected from urban/suburb, agricultural, and forest areas, and screened for less-studied AAL/O analogues with high-resolution mass spectrometry. 1,3-Diphenylguanidine (DPG; median concentration: 121 ng/g) and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q; 9.75 ng/g) are the most abundant congeners, constituting 69.7% and 41.4% of the total concentrations of AAL/Os (192 ng/g) and those of AAO transformation products (22.3 ng/g), respectively. The spatial distribution across the studied sites suggests evident human impacts, reflected by the pronounced urban signature and vehicle-originated pollution. Our nontargeted analysis of the most-contaminated road dust identified 16 AAL/O-related chemicals, many of which have received little investigation. Particularly, environmental and toxicological information remains extremely scarce for five out of the 10 most concerning compounds prioritized in terms of their dusty residues and toxicity including 1,2-diphenyl-3-cyclohexylguanidine (DPCG), N,N''-bis[2-(propan-2-yl)phenyl]guanidine (BPPG), and N-(4-anilinophenyl)formamide (PPD-CHO). Additionally, dicyclohexylamine (DChA), broadly applied as an antioxidant in automobile products, had an even greater median level than DPG. Therefore, future research on their health risks and (eco)toxic potential is of high importance.

Amino accelerators and antioxidants in sediments from the Dong Nai River System, Vietnam: Distribution and influential factors.

Amino accelerators and antioxidants (AAL/Os) have become a suite of contaminants of emerging concern recently due to the accumulating evidence for their environmental occurrence and associated toxic potential. Nevertheless, data on sedimentary deposition of AAL/Os has remained scarce, particularly for regions beyond the North America. In the present study, we elucidated spatial distribution of fifteen AAL/Os and five AAO transformation products (AAOTPs) in seventy-seven sediments from the Dong Nai River System (DNRS), Vietnam. Total concentrations of AAL/Os (∑AAL/Os) ranged from 0.377 to 51.4 ng/g (median: 5.01 ng/g). 1,3-Diphenylguanidine and 4,4'-bis(1,1-dimethylbenzyl) diphenylamine were the two most prevalent congeners, both with detection frequencies >80%. Additionally, AAOTPs were quantifiable in 79% of the DNRS sediments with a median ∑AAOTPs at 2.19 ng/g, dominated by N, N'-diphenylbenzidine and 2-nitrodiphenylamine. Higher sediment-associated levels of AAL/Os and AAOTPs were spotted in downstream and the primary tributary of the DNRS compared to the upstream, implying their cumulative sedimentation towards the estuarine region. The distribution patterns of AAL/Os and AAOTPs across individual transects also demonstrated the influence of human activities (e.g., urbanization and agriculture), hydrodynamics, and decontamination by mangrove reserves. Meanwhile, characteristics of sediments, i.e., total organic carbon (TOC) content and grain sizes, exhibited significant correlations with the burdens of these compounds, indicating their preferential partitioning into the fine and TOC-rich matter. This research sheds light on environmental behavior of AAL/Os and AAOTPs beneath Asian aquatic system, and highlights the need for further evaluation of their impacts on the wildlife and public health.

Simulation and risk assessment of arsenic by Hydrus-3D and CalTOX in a typical brownfield site.

Accurate quantification of arsenic migration and accumulation in brownfield site is critical for environmental management and soil remediation. However, the researches simulating arsenic in brownfield site in China are limited due to sparse data and complex migration behaviors. In this study, we simulated historic arsenic contamination using Hydrus-3D in an abandoned brownfield site in Hebei, China, from 1972 to 2019. Atmospheric discharge, wastewater leakage, solid waste discharge and tank leakage were calculated according to the factory processes for model simulation. Based on the results of Hydrus-3D, we assessed health risk of arsenic in this site. The results showed that total arsenic input to the soil surface from 4 pathways was 24.6 tons, the solid waste discharge was the highest contributor. The accumulation process mainly occurred in the unsaturated zone due to clay and silty clay absorbed arsenic and thus slow down the migration process. While in the saturation zone, abundant groundwater promoted migration of arsenic, resulting in widespread distribution of contaminated area. The model results represented good performance between simulated and measured values. Sensitivity analysis indicated that adsorption constant and water conductivity were the most influential parameters. Heath risk assessment showed that arsenic contamination continues to threaten resident health.

Amino antioxidants: A review of their environmental behavior, human exposure, and aquatic toxicity.

Amino antioxidants (AAOs), a suite of emerging organic contaminants, have been widely used in numerous industrial and commercial products to inhibit oxidation and corrosion. Recently, their environmental ubiquity, health risks, bioaccumulative and toxic potential have led to mounting public concern. This review summarizes the current state of knowledge on the production and usage, environmental occurrence, bioavailability, human exposure, and aquatic toxicity of representative AAOs, and provides suggestions for future research directions. Previous studies have revealed widespread distribution of many AAOs in various environmental matrixes, including air, water, sediment, dust, and biota. In addition to parent compounds, their degradation products, such as 2-anilino-5-(1,3-dimethylbutylamino)-1,4-benzoquinone (6PPD-Q) and 4-nitrodiphenylamine (4-NO2-DPA), have also been detected at high levels in multiple compartments. Dust ingestion and air inhalation are the two most well-investigated routes for human exposure to AAOs and their transformation products, while studies on other pathways (e.g., skin contact and dietary intake) still remain extremely limited. Moreover, AAO burdens in human tissue have been poorly documented. Toxicological data have shown that a few AAOs may cause teratogenic, developmental, reproductive, endocrinic, neuronic, and genetic toxicity to aquatic organisms, and the toxic capacities of degradation products differ from their precursors. Future studies should focus on elucidating AAO exposure for humans and associated health risks. Additionally, more attention should be given to AAO transformation products (particularly those quinoid derivatives possessing substantial affinity with DNA) and to the effects of complex mixtures of these chemicals.

An improved hybrid model on source-risk of polycyclic aromatic hydrocarbon in soils of the Yangtze River Delta urban agglomeration.

The source, exposure and risks of polycyclic aromatic hydrocarbons (PAHs) in soil environments are of great importance to evaluate soil quality. However, understanding the risks of specific sources of PAHs in soils remains poorly understood. In this study, we determined the source, exposure and risks of PAHs in the Yangtze River Delta urban agglomeration. The source analysis receptor model combined with land use types significantly increased the identification of pollution sources and improved the prediction accuracy of PAH concentrations. There is a strong correlation between the measured and predicted values of high ring PAH. The correlations of BbF, InP and Pyr are 0.947, 0.896 and 0.906 respectively, which is significantly higher than the unmodified model. By combining the ecological risk assessment and health risk assessment models of PAHs, we established an improved mixed source-risk model. The PAHs in urban soils had the highest ecological risk and health risk, with risk probabilities of 56.3 % and 28.2 %, respectively. The average contamination severity index values of PAHs caused by oil combustion sources, coal combustion sources, coking furnace sources, and fuel (biomass, petroleum, and diesel) combustion sources were 0.13, 0.10, 0.16 and 0.17, respectively. The average noncarcinogenic risks of PAHs from oil combustion sources, coal combustion sources, coking furnace sources and biomass, petroleum volatilization and diesel combustion sources to children were 0.12, 0.11, 0.08 and 0.13, respectively. Approximately half of the PAH pollution risk in forestland and grassland soil were associated with the combustion of petroleum fossil fuels. This study quantitatively analyzed the contribution of different PAHs pollution sources in different land types of soils, further calculated the risks of each pollution source to the ecological environment and human health, and proposed corresponding treatment measures, which provided scientific and systematic methods and technologies for soil pollution management in other regions of the world.