Relationship between levels of polycyclic aromatic hydrocarbons in pine needles and socio-geographic parameters

Concentrations, phase exchanges and source apportionment of polycyclic aromatic hydrocarbons (PAHs) In Bursa-Turkey

The present study aimed to determine the pollution levels derived from polycyclic aromatic hydrocarbons (PAHs) in air, plant and soil samples and to reveal the PAH exchange at the soil-air, soil-plant and plant-air interfaces. In this context, air and soil samples were collected in approximately 10-day periods between June 2021 and February 2022 from a semi-urban area in Bursa, an industrial city with a dense population. Also, plant branch samples were collected for the last three months. Total PAH concentrations in the atmosphere (∑₁₆PAH) and soil (∑₁₄PAH) ranged from 4.03 to 64.6 ng/m³ and 13-189.4 ng/g DM, respectively. PAH levels in the tree branches varied between 256.6 and 419.75 ng/g DM. In all air and soil samples, PAH levels were low in the summer and reached higher values in the winter. 3-ring PAHs were the dominant compounds, and their distribution in air and soil samples varied between 28.9%-71.9% and 22.8%-57.7%, respectively. According to the results of diagnostic ratios (DRs) and principal component analysis (PCA), both pyrolytic and petrogenic sources were found to be effective in PAH pollution in the sampling region. The fugacity fraction (ff) ratio and net flux (F_net) values indicated that the direction of movement of PAHs was from soil to air. In order to better understand the PAH movement in the environment, soil-plant exchange calculations were also achieved. The ratio of ∑₁₄PAH values measured to modeled concentrations (1.19<ratio<1.52) revealed that the model worked well for the sampling region and produced reasonable results. The ff and F_net levels showed that branches were saturated with PAHs and the direction of PAH movement was from plant to soil. The plant-air exchange results indicated that the direction of movement of PAHs was from plant to air for low molecular weight PAHs and the opposite was true for compounds with high molecular weight ones.

Plant-air partition coefficients for thirteen urban conifer tree species: Estimating the best gas and particulate matter associated PAH removers

Polycyclic Aromatic Hydrocarbons (PAHs) are an important class of pollutants which mostly come out from incomplete combustion of organic materials including fossil fuels. For this reason, they are often found at high concentrations in cities, contaminating air with their gas and particle phase. While European Union policies try to reduce their concentrations, huge efforts are still devoted to mitigate the pollution by PAHs. One such measure of mitigation is the use of plants in capturing PAHs and other chemicals due to the ability of leaves in filtering both gas and particle fractions. In this work thirteen conifer species among those frequently living in temperate and Mediterranean cities were selected and concentrations of 16 PAHs were measured in needles. The data for spruce were used to back-calculate air concentrations of PAHs which were later used to obtain specific equations of plant-air partition coefficient (K_PA). The results showed that the difference in total PAH uptake between the most (Pinus pinaster) and the least (Picea abies) efficient tree was close to an order of magnitude. Looking to the capability of the different species in enriching the particulate matter (PM) associated fraction of PAHs on their needles, Pinus pinaster was instead the least important (3.4% of total PAHs), while Cupressus lusitanica was the most important (34% of total PAHs). The new K_PA equations can be used to fine tune the PAH uptake of a specific amount of plant biomass on air concentration reduction.

Tracing historical changes, degradation, and original sources of airborne polycyclic aromatic hydrocarbons (PAHs) in Jilin Province, China, by Abies holophylla and Pinus tabuliformis needle leaves

Due to their wide distribution and availability, plant leaves can be considered interesting candidates as biomonitoring substrates for the evaluation of atmospheric pollution. In addition, some species can also retain historical information, for example, related to environmental pollution, due to their leaf class age. In this study, the content of polycyclic aromatic hydrocarbons (PAHs) in Abies holophylla and Pinus tabuliformis needle samples in the function of their class age has been investigated to obtain information regarding the degradation constant for each PAH under investigation (α values ranging from 0.173 to 1.870) and to evaluate the possibility to correlate the presence of PAHs in needles with some important pollution environmental factors. Considering air pollutant variables registered in Jilin Province, interesting correlations (at 95% confidence level) have been found between coal consumption per year and anthracene contents in needles, while fluorene, phenanthrene, and anthracene results correlated with coal consumption. Furthermore, it has been demonstrated that the total PAH concentration in needles, for both species, increased with their age (from 804 to 3604 ng g^-1 dry weight), showing a general tendency to accumulate these substances through years. PAH degradation rates increased instead with molecular complexity. This study could be considered a first trial to obtain historical environmental information by pine needles biomonitoring.

Levels, distributions, and seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in ambient air and pine components

Pine tree (Pinus pinea) components have been used as passive air samples for determining atmospheric polycyclic aromatic hydrocarbon (PAH) concentrations. Our results indicated that pine needles and branches were found to be statistically successful in describing the ambient air. Monthly pine needles, branches (1- and 2-year-old) and ambient air samples were collected for 1 year to identify molecular distributions and temporal concentrations of PAHs in a suburban-industrial area. Annual average Σ₁₄PAH concentrations for pine needles, 1- and 2-year-old branches, and ambient air were 756 ± 232 ng/g DW, 685 ± 350 ng/g DW, 587 ± 361 ng/g DW, and 28.29 ± 32.33 ng/m³, respectively. The order of average Σ₁₄PAH concentrations in the pine tree components was determined as needle > 1-year-old branch > 2-year-old branch. In general, concentrations increased with the rise in the surface area of tree components. In the samples, 3- and 4-ring PAHs were dominant compounds in the ambient air, pine needles, and branches. The annual total fraction of 3- and 4-ring PAHs in the air was 98.5%, while the fraction of 5- and 6-ring PAHs was 1.5%. On the other hand, 3- and 4-ring PAHs in pine needles and branches were 30% or more. The fraction and level of PAHs change with the season. Although needle samples did not show any seasonal trend, PAH levels in other tree components changed with the air temperature. Generally, lower values were observed in warmer seasons in the branch samples. Similarly, ambient air PAH concentrations were higher in the winter season due to heating and adverse meteorological conditions.

The use of vegetation, bees, and snails as important tools for the biomonitoring of atmospheric pollution-a review

The continuous discharge of diverse chemical products in the environment is nowadays of great concern to the whole world as some of them persist in the environment leading to serious diseases. Several sampling techniques have been used for the characterization of this chemical pollution, although biomonitoring using natural samplers has recently become the technique of choice in this field due to its efficiency, specificity, and low cost. In fact, several living organisms known as biomonitors could accumulate the well-known persistent environmental pollutants allowing their monitoring in the environment. In this work, a review on environmental biomonitoring is presented. The main sampling techniques used for monitoring environmental pollutants are first reported, followed by an overview on well-known natural species used as passive samplers and known as biomonitors. These species include conifer needles, lichen, mosses, bees and their byproducts, and snails, and were widely used in recent research as reliable monitors for environmental pollution.

Interspecific differences in foliar 1 PAHs load between Scots pine, birch, and wild rosemary from three polish peat bogs

Pine needles are one of the most commonly used bioindicators of polycyclic aromatic hydrocarbons (PAHs) in the environment. Therefore, the main objective of the current research was the assessment of PAHs accumulation potential of Scots pine (Pinus sylvestris L.) needles in comparison to wild rosemary (Rhododendron tomentosum Harmaja) and birch (Betula spp.) leaves. Our study was carried out on three peat bogs subjected to different degree of anthropopression, which gave us also the opportunity to identify local emission sources. Pine needles had the lowest accumulation potential from all the studied species. The highest accumulation potential, and hence carcinogenic potential, was observed for wild rosemary leaves. As far as emission sources are concerned, the most pronounced influence on atmospheric PAHs loads had traditional charcoal production, resulting in great influx of heavy PAHs. Observed seasonal changes in PAHs concentrations followed the pattern of winter increase, caused mainly by heating season, and summer decrease, caused mainly by volatilization of light PAHs.

Sources and environmental processes of polycyclic aromatic hydrocarbons and mercury along a southern slope of the Central Himalayas, Nepal

Semi-volatile pollutants can undergo long-range atmospheric transport from low-altitude source regions to high-altitude regions and then accumulate in surface matrices (soil and plants). The Himalayas is the highest mountain range worldwide, but there have been limited studies on the source, transport, and deposition of polycyclic aromatic hydrocarbons (PAHs) and mercury (Hg) in the region. In this study, atmospheric PAHs, and the PAHs and Hg in soil and foliage were determined along a transect on a southern slope of the Himalayas, Nepal. The study showed anthropogenic emissions of PAHs and Hg occurred in the lowland areas of Nepal, and upslope transport to the high-altitude regions happened for both pollutants. During the upslope transport, forest filter effect and snow scavenging may be the important factors that enhance the deposition of PAHs, contributing to the negative pattern between concentrations of PAHs and altitudes. On the contrary, more Hg accumulated in the high Himalayas, relating to the enhanced deposition in the high altitude caused by the higher input from upper atmosphere. Graphical abstract Distribution and environmental processes of PAHs and Hg along the southern slope of Himalayan mountain.