Development of a Multifaceted Perspective for Systematic Analysis, Assessment, and Performance for Environmental Standards of Contaminated Sites.

Contaminated soil and groundwater can pose significant risks to human health and ecological environments, making the remediation of contaminated sites a pressing and sustained challenge. It is significant to identify key performance indicators and advance environmental management standards of contaminated sites. The traditional study currently focuses on the inflexible collection of related files and displays configurable limitations regarding integrated assessment and in-depth analysis of published standards. In addition, there is a relative lack of research focusing on the analysis of different types of standard documents. Herein, we introduce a cross-systematic retrospective and review for the development of standards of the contaminated sites, including the comprehensive framework, multifaceted analysis, and improved suggestion of soil and groundwater standards related to the environment. The classification and structural characteristics of different types of files are systematically analyzed of over 300 national, trade, local, and group standards for the contaminated sites. It exhibits that trade standards are the main types and testing methods are the important format within numerical considerations of soil standards. The guide standard serves as a crucial component in environmental management for investigating, assessing, and remediating of contaminated sites. Future improvement plans and development directions are proposed for advancing robust technical support for effective soil contamination prevention and control. This multidimensional analysis and the accompanying suggestions can provide improved guidance for Chinese environmental management of contaminated sites and sparkle the application of standards in a wide range of countries.

Development of a new methodology for multifaceted assessment, analysis, and characterization of soil contamination.

It is important to identify key performance and core progress features of soil contamination management practices. Traditional research currently focuses on numerical statistics of contaminated sites but exhibits structural limitations regarding cross-assessment and in-depth analysis of published findings. Herein, we report a multidimensional perspective to assess the environmental management performance of soil contamination via systematic and historical development of construction land risk control and remediation lists (RCRLs). The considered contaminated sites are mainly concentrated in Northern China, Yangtze River Delta, Pearl River Delta, and Sichuan-Chongqing regions. Monthly historical overviews indicate that most lists are updated 4-5 times within 32 months. Direct chemical-related industrial production results in the largest number of contaminated sites. Arsenic and lead are the most common heavy metals of concern in soil contamination. The fiscal revenue index exhibits the best positive performance in terms of the number of contaminated sites. By employing the site number, update frequency, and published contents of different calculation proportions, ten types of integrated assessment indicators (IAIs) are established to evaluate the environmental achievements in various provincial regions in regard to soil contamination protection. This multifaceted strategy can provide advanced guidance for Chinese environmental management and expand the application of soil pollution risk control and remediation in a wide range of countries.

Controllable Design and Preparation of Hollow Carbon-Based Nanotubes for Asymmetric Supercapacitors and Capacitive Deionization.

Carbon-based materials are important desirable materials in areas such as supercapacitors and capacitive deionization. However, traditional commercial materials are heterogeneous and prone to agglomeration in nanoscale and have structural limitation of electrochemical and desalination performance due to poor transport channels and low capacitance of prepared electrodes. Here, we introduce the facile strategy for controllable preparation of two types of hollow carbon-based nanotubes (HCTs) with amorphous mesoporous structures, which are synthesized by employing a MnO2 linear template method and calcination of polymer precursors. The porous N-doped HCT (NHCT) shows a specific capacitance of 412.6 F g-1 (1 A g-1), with 77.3% rate capability (20 A g-1). The fabricated asymmetric MnO2//NHCT supercapacitor displays the energy density of 55.8 Wh kg-1 at a power density of 803.9 W kg-1. Furthermore, two typical MnO2//HCT and MnO2//NHCT devices both show the selective desalination performance of sulfate, and the MnO2//NHCT device possesses a high deionization value of 11.37 mg g-1 (500 mg L-1 Na2SO4). These fabricated hollow carbon-based architectures with functional characteristics promise potential applications in energy and environmental related fields.

History of petroleum disturbance triggering the depth-resolved assembly process of microbial communities in the vadose zone.

Biogeochemical gradient forms in vadose zone, yet little is known about the assembly processes of microbial communities in this zone under petroleum disturbance. This study collected vadose zone soils at three sites with 0, 5, and 30 years of petroleum contamination to unravel the vertical microbial community successions and their assembly mechanisms. The results showed that petroleum hydrocarbons exhibited higher concentrations at the long-term contaminated site, showing negative impacts on some soil properties, retarding in the surface soils and decreasing along soil depth. Cultivable fraction of heterotrophic bacteria and microbial α-diversity decreased along depth in vadose zones with short-term/no contamination history, but exhibited an opposite trend with long-term contamination history. Petroleum contamination intensified the vertical heterogeneity of microbial communities based on the contamination time. Microbial co-occurrence network revealed the lowest species co-occurrence pattern at the long-term contaminated site. The distance-decay patterns and null model analysis together suggested distinct assembly mechanisms at three sites, where dispersal limitation (42-45%) was higher and variable and homogenizing selections were lower (37-38%) in vadose zones under petroleum disturbance than those in the uncontaminated vadose zone. Our findings help to better understand the subsurface biogeochemical cycles and bioremediation of petroleum-contaminated vadose zones.

Geo-distribution pattern of microbial carbon cycling genes responsive to petroleum contamination in continental horizontal oilfields.

Contamination significantly affects soil microbial community structures, and the metabolisms of organic contaminants might particularly alter soil carbon cycling by shaping microbial carbon cycling genes. Although numerous studies have discussed the impacts of petroleum contamination on soil bacterial communities and relevant degrading genes, there is no work addressing how soil carbon cycling genes are affected by petroleum contamination. In this study, 77 soil samples were collected from five typical oilfields horizontally located in China to explore the influence of environmental variables and petroleum contamination on microbial carbon cycling genes. Results from Geochip suggested a geographic-determined distribution of carbon cycling genes. Although no significant correlation was observed between carbon cycling genes and soil physio-chemical properties for all soils, some relationships were identified in specific oilfield. Principle component analysis indicated that soil physio-chemical properties, rather than petroleum contamination disturbance, are the key factors determining the degree of sample dispersion, whereas environmental variables predominantly control the degree of sample aggregation. Co-occurrence ecological network analysis revealed a more complex interactions of all functional genes in petroleum-contaminated soils, and carbon cycling genes were grouped with nitrogen related genes in petroleum-contaminated communities. Soil moisture and heterogeneity were identified as the main drivers for the abundance and diversity of carbon cycling genes, particularly in petroleum-contaminated soils. These results are attributing to the fewer impacts of petroleum contamination on the diversity of carbon cycling genes than soil physio-chemical properties, and soil carbon cycling genes are mainly driven by geographic location and petroleum contamination together. Our findings provide deeper insight into the influence of petroleum contamination in soil microbial functions related to carbon cycling.

Disturbance, carbon physicochemical structure, and soil microenvironment codetermine soil organic carbon stability in oilfields.

The stability of soil organic carbon (SOC) is crucial for soil quality, fertility, and natural attenuation processes of pollutants. The physicochemical structures of SOC were believed to control its stability, yet has become controversial. Here we hypothesized that disturbance intensity and variations in the soil environment can also influence the SOC stability, and conducted a case study with oil contaminated soils to quantify the contributions to SOC stability of various factors including contamination level, carbon physicochemical structure, and soil properties. Oil contamination led to increased SOC stability, as suggested by appreciably decreased soil CO2 fluxes, the enrichment of the δ13C in the oil contaminated soils, as well as analysis of soil aggregates and humic substances. Redundancy analysis indicated that overall SOC stability were highly correlated to microaggregate (M2), HA/FA, Fe, soil porosity, EC, pH, and total petroleum hydrocarbon (TPH) in oilfields. Variance partitioning analysis showed that carbon physicochemical structure (S), soil properties (P), and oil contamination (O) could explain the variance of overall SOC stability by up to 90%, while 18% of the variation was explained by S × P and 43% by S × P × O. These results show that multiple factors of the disturbance, carbon physicochemical structure, and soil properties should be essential for future studies of SOC stability.