Surface horizons of forest soils for the diagnosis of soil environment contamination and toxicity caused by polycyclic aromatic hydrocarbons (PAHs)

The main strategies for soil pollution apportionment: A review of the numerical methods

Nowadays, a large number of compounds with different physical and chemical properties have been determined in soil. Environmental behaviors and source identification of pollutants in soil are the foundation of soil pollution control. Identification and quantitative analysis of potential pollution sources are the prerequisites for its prevention and control. Many efforts have made to develop methods for identifying the sources of soil pollutants. These efforts have involved the measurement of source and receptor parameters and the analysis of their relationships via numerical statistics methods. We have comprehensively reviewed the progress made in the development of source apportionment methodologies to date and present our synthesis. The numerical methods, such as spatial geostatistics analysis, receptor models, and machine learning methods are addressed in depth. In most cases, however, the effectiveness of any single approach for source apportionment remains limited. Combining multiple methods to address soil quality problems can reduce uncertainty about the sources of soil pollution. This review also constructively highlights the key strategies of combining mathematical models with the assessment of chemical profiles to provide more accurate source attribution. This review intends to provide a comprehensive summary of source apportionment methodologies to help promote further development.

Polycyclic Aromatic Hydrocarbons in Soil at Different Depths under a Long-Term Experiment Depending on Fertilization

The aim of this study was to assess the effect of long-term fertilization with manure and mineral fertilizers on the content and distribution of selected polycyclic aromatic hydrocarbons (PAHs)-the content of a sum of 16 polycyclic aromatic hydrocarbons, light and heavy PAHs in two soil layers (0-30 cm and 30-60 cm). The material for the study was composed of soil samples collected from the sixth rotation in a long-term, controlled field experiment, conducted in Bałcyny since 1986. The content of 16 polycyclic aromatic hydrocarbons was determined on a gas chromatographer coupled with an FID detector. In order to evaluate the significance of differences between the mean effects on the tested characteristics, a non-parametric Mann-Whitney U test for two independent samples was applied. A higher content of the sum (16) of PAHs was found in the 0-30 cm than in the 30-60 cm soil layer. The research results also demonstrated a higher content of the sum of light PAHs in the 30-60 cm than in the 0-30 cm soil layer. The content of heavy PAHs, in turn, was significantly higher in the upper than in the deeper soil layer. This dependence appeared in both the soil fertilized with manure and soil nourished only with mineral fertilizers.

Environmental and human health risk assessments of polycyclic aromatic hydrocarbons in particulate matter in Nigeria

Polycyclic aromatic hydrocarbons (PAHs) are an important organic group in particulate matter which has attracted much attention among the scientific community in terms of health risk because of their carcinogenic, mutagenic, and ubiquitous nature in the environment. In this study, PAHs in particulate matter in Okitipupa were determined. Indoor and outdoor particle samples were sampled with the aid of SKC Air Check XR5000 high-volume gravimetric sampler, and analyzed using gas chromatography flame ionization detector (GC-FID). The results obtained showed that high molecular weight PAHs (5-ring, 6-ring PAHs) had higher mean concentration than low molecular weight PAHs (2-ring, 3-ring PAHs), in both indoor and outdoor particulate matter. Health risk assessments from exposure to these PAHs were also determined using toxicity equivalence quotient (TEQ), mutagenicity equivalence quotient (MEQ), incremental life cancer risk (ILCR), and hazard quotient (HQ). Dibenz(a,h)anthracene had the highest mean concentration across the sample location in both indoor and outdoor with values ranging from 33 to 31 and 90 to 93 µg/m³ respectively. The total mean concentration in outdoor PAHs ranged from 280 to 329 µg/m³, while total mean concentration in indoor PAHs ranged from 74 to 104 µg/m³. The incremental lifetime cancer risk in indoor ranged from 6.9 × 10^-7 to 1.2 × 10^-5, while the ILCR in outdoor ranged from 8.5 × 10^-6 to 1.0 × 10^-5. The hazard quotient in indoor ranged from 7.6 × 10^-5 to 2.2 × 10^-3, while the HQ in outdoor ranged from 10 × 10^-4 to 1.4 × 10^-3. These values are within the WHO permissible limit, and therefore underscores the danger associated with the inhalation of polycyclic aromatic hydrocarbons in Okitipupa.

Screening Risk Assessment of Agricultural Areas under a High Level of Anthropopressure Based on Chemical Indexes and VIS-NIR Spectroscopy

Intensive anthropogenic activity may result in uncontrolled release of various pollutants that ultimately accumulate in soils and may adversely affect ecosystems and human health. Hazard screening, prioritisation and subsequent risk assessment are usually performed on a chemical-by-chemical basis and need expensive and time-consuming methods. Therefore, there is a need to look for fast and reliable methods of risk assessment and contamination prediction in soils. One promising technique in this regard is visible and near infrared (VIS-NIR) spectroscopy. The aim of the study was to evaluate potential environmental risk in soils subjected to high level of anthropopressure using VIS-NIR spectroscopy and to calculate several risk indexes for both individual polycyclic aromatic hydrocarbons (PAHs) and their mixture. Results showed that regarding 16PAH concentration, 78% of soil samples were contaminated. Risk assessment using the most conservative approach based on hazard quotients (HQ) for 10 individual PAHs allowed to conclude that 62% of the study area needs further action. Application of concentration addition or response addition models for 16PAHs mixture gave a more realistic assessment and indicates unacceptable risk in 23% and 55% of soils according to toxic units (TUm) and toxic pressure (TPm) approach. Toxic equivalency quotients (TEQ) were below the safe limit for human health protection in 88% of samples from study region. We present here the first attempt at predicting risk indexes using VIS-NIR spectroscopy. The best results were obtained with binary models. The accuracy of binary model can be ordered as follows: TPm (71.6%) < HI (85.1%) < TUm (87.9%) and TEQ (94.6%). Both chemical indexes and VIS-NIR can be successfully applied for first-tier risk assessment.