Enhancing the release and plant uptake of PAHs with a water-soluble purine alkaloid

Study on reproductive endocrine disturbance and DNA damage mechanism of female Ruditapes philippinarum under Benzo[a]pyrene stress

The reproductive toxicity of polycyclic aromatic hydrocarbons (PAHs) in aquatic organisms has attracted increasing attention from scholars. Currently, research in this field primarily focuses on vertebrates such as zebrafish and other model species. However, there is still a significant knowledge gap in the toxicity of PAHs to invertebrates and its potential mechanisms. Benzo[a]pyrene (B[a]P) is one of the most representative PAHs. In this study, female Ruditapes philippinarum (R. philippinarum) was treated with B[a]P concentrations of 0, 0.8, 4, and 20 μg/L to investigate reproductive indicators in the proliferative, growth, mature, and spawn stages. Transcriptomics was used to investigate the expression of genes associated with the reproductive endocrine system, DNA repair, autophagy, apoptosis, and ovarian development at different reproductive stages. Our results suggested that B[a]P disrupted the endocrine system by interfering with the production of steroid hormones and the transmission of estrogen signals in female R. philippinarum. The structure of the ovarian DNA duplex is severely damaged under the stress of B[a]P, and a series of cellular responses caused by DNA damage are also interfered. Additionally, we observed a reduction in the gonadosomatic index (GSI) and mature oocytes numbers after B[a]P exposed. Tissue section indicated that severe damage to the ovarian structure at mature and spawn stages. In conclusion, this study combined transcriptomic and toxicological to explore the negative effects on ovarian development induced by B[a]P, focusing on reproductive endocrine disturbance and DNA damage.

Phytoremediation of pyrene-contaminated soils: A critical review of the key factors affecting the fate of pyrene

Soil contamination by pyrene has increased over the years due to human-related activities, urgently demanding for remediation approaches to ensure human and environment safety. Within this frame, phytoremediation has been successfully applied over the years due to its green and cost-effectiveness features. The scope of this review includes the main phytoremediation mechanisms correlated with the removal of pyrene from contaminated soils and sediments to highlight the impact of different parameters and the supplement of additives on the efficiency of the treatment. Soil organic matter (SOM), plant species, aging time, environmental parameters (pH, soil oxygenation, and temperature) and bioavailability are among the main parameters affecting pyrene removal through phytoremediation. Phytoextraction only accounts for a small part of the entire phytoremediation process, but the addition of surfactants and chelating agents in planted soils could increase pyrene accumulation in plant tissues by 20% as a consequence of the increased pyrene bioavailability. Rhizodegradation is the main phytoremediation mechanism involved due to the activity of bacteria capable of degrading pyrene in the root area. Inoculated-planted soil treatments have the potential to decrease pyrene accumulation in shoots and roots by approximately 30 and 40%, respectively, further stimulating the proliferation of pyrene-degrading bacteria in the rhizosphere. Plant-fungi symbiotic association results in an enhanced accumulation of pyrene in shoots and roots of plants as well as a higher biodegradation. Finally, pyrene removal from soil can be improved in the presence of amendments, such as natural non-ionic surfactants, biochar, and bacterial mixtures.

Negative role of biochars in the dissipation and vegetable uptake of polycyclic aromatic hydrocarbons (PAHs) in an agricultural soil: Cautions for application of biochars to remediate PAHs-contaminated soil

Biochars were studied for their impacts on the dissipation and vegetable uptake of polycyclic aromatic hydrocarbons (PAHs) in an agricultural soil. The health risks of PAHs taken up by vegetables were assessed by growing Chinese cabbage in both unamended soil and biochar-amended soils. In the unamended soil, the total 16 PAHs (Σ16PAHs) content decreased by 77.38% after planting the vegetable. The dissipation percentages of low-molecular-weight PAHs (LMW-PAHs), medium-molecular-weight PAHs (MMW-PAHs), and high-molecular-weight PAHs (HMW-PAHs) were 82.37%, 72.65%, and 68.63%, respectively. A significant negative correlation was determined between the dissipation percentages of PAHs in soil and the logK_ow of PAHs (p < 0.01), indicating that the affinity of PAHs for soil particles was one of an important limiting factors on the dissipation of PAHs. The uptake of PAHs by plant was significantly reduced with the increase in the molecular weight of the PAHs (76.55% for LWM-PAHs, 17.13% for MMW-PAHs, and 6.05% for HMW-PAHs). Addition of biochars to the soil decreased the dissipation of Σ16PAHs (73.59-77.01%), mostly due to a decrease in the dissipation of LMW-PAHs and MMW-PAHs. This finding was due to the immobilization of LMW-PAHs and MMW-PAHs within the biochar micropores. A marked reduction of Proteobacteria in biochar-amended soils also resulted in the decreased biodegradation of PAHs. Four of six biochars significantly increased the concentrations of Σ16PAHs in plant by 30.10-74.22%. Generally, biochars significantly increased the uptake of LMW-PAHs by plant but had little influence on the plant uptake of MMW-PAHs and HMW-PAHs. Three of six biochars notably increased the incremental lifetime cancer risk values based on the exposure of PAHs by vegetable consumption.

Polycyclic aromatic hydrocarbons in coffee samples: Enquiry into processes and analytical methods

Polycyclic aromatic hydrocarbons (PAHs) are considered to be potentially genotoxic and carcinogenic in humans. These ubiquitous environmental pollutants may derive from the incomplete combustion and pyrolysis of organic matter. Coffee is an extensively consumed drink, and its PAHs contamination is not only ascribed to environmental pollution, but mainly to the roasting processes. Although no fixed limits have yet been set for residual PAHs in coffee, the present review intends to summarise and discuss the knowledge and recent advances in PAHs formation during roasting. Because coffee origin and brewing operations may affect PAHs content, we thoroughly analysed the literature on extraction and purification procedures, as well as the main analytical chromatographic methods for both coffee powders and brews. With regards to the safety of this appreciated commodity, the control on the entire production chain is desirable, because of coffee beverage could contribute to the daily human intake of PAHs.

Glomalin-related soil protein influences the accumulation of polycyclic aromatic hydrocarbons by plant roots

Studies have demonstrated that the inoculation of soil with arbuscular mycorrhizal fungi (AMF) enhances the content of glomalin-related soil protein (GRSP), which in turn elevates the availability of polycyclic aromatic hydrocarbons (PAHs) in soil. However, few studies have examined the influence of GRSP on PAH accumulation by plants and their tissues. Understanding of this issue would provide new perspectives on the role of GRSP in PAH uptake by plants at contaminated sites. This investigation was the first observational study of the GRSP-influenced PAH accumulation in roots of ryegrass (Lolium multiflorum Lam.). GRSP (0-120 mg/L) enhanced the root PAH accumulation in a GRSP-concentration-dependent manner, based on the observed root concentrations and root concentration factors (RCFs). The greatest enhancement of ΣPAH accumulation appeared at 40 mg/L of the total GRSP (T-GRSP) and 80 mg/L of the easily extracted GRSP (EE-GRSP), respectively. The weakly and strongly adsorbed fractions accounted for 88.8-94.4%, while the absorbed fraction contributed no >11.2% of total PAH accumulation in roots. The capacity of PAH adsorption on roots was enlarged in the presence of GRSP (0-120 mg/L). As the adsorbed fraction dominated the total PAH contents in roots overwhelmingly, the GRSP-induced changes in root PAH accumulation were ascribed to GRSP-affected PAH sorption by roots.

Plant uptake and translocation of contaminants of emerging concern in soil

The advent of industrialization has led to the discovery of a wide range of chemicals designed for multiple uses including plant protection. However, after use, most of the chemicals and their derivatives end up in soil and water, interacting with living organisms. Plants, which are primary producers, are intentionally or unintentionally exposed to several chemicals, serving as a vehicle for the transfer of products into the food chain. Although the exposure of pesticides towards plants has been witnessed over a long time in agricultural production, other chemicals have attracted attention very recently. In this review, we carried out a comprehensive overview of the plant uptake capacity of various contaminants of emerging concern (CEC) in soil, such as pesticides, polycyclic aromatic hydrocarbons, perfluorinated compounds, pharmaceutical and personal care products, and engineered nanomaterials. The uptake pathways and overall impacts of these chemicals are highlighted. According to the literature, bioaccumulation of CEC in the root part is higher than in aerial parts. Furthermore, various factors such as plant species, pollutant type, and microbial interactions influence the overall uptake. Lastly, environmental factors such as soil erosion and temperature can also affect the CEC bioavailability towards plants.

Dietary risk evaluation for 28 polycyclic aromatic hydrocarbons (PAHs) in tea preparations made of teas available on the Polish retail market

The aim of this work was to assess dietary risk resulting from consumption of polycyclic aromatic hydrocarbons (PAHs) with tea infusions. To this end, levels of 28 PAHs in black, green, red and white teas available on the Polish retail market have been assessed. Profiles and correlation between concentrations of individual PAHs have been identified. A model study on transfer of PAHs from tea leaves into tea preparations has been conducted. Relatively high concentrations of 28 evaluated PAHs have been found in 58 tested samples of black, green, red and white teas sampled on the Polish retail market. Total concentration ∑28PAH ranged from 57 to 696 µg kg^-1 with mean 258 µg kg^-1 (dry tea leaves). The most mature tea leaves fermented to a small degree contained relatively the highest PAH levels among all four tested tea types. Relatively low PAH transfer rates into tea infusions and limited volumes of the consumed tea keep the risks associated with PAH dietary intake at a safely low level. The worst-case scenario dietary intake values were 7.62/0.82/0.097 ng kg^-1 b.w. day^-1 (estimated on the basis of the maximum found concentrations 696/113/23 µg kg^-1 and maximum observed transfer rates 24/16/9%) for ∑28PAH/∑PAH4/B[a]P, respectively. MOE values calculated using the above worst case estimates exceeded 700,000 and 400,000 (BMDL₁₀ 0.07 and 0.34 mg kg^-1 b.w. day^-1) for B[a]P and PAH4, respectively. Both B[a]P and PAH4 concentrations may be used as indicators of total PAH concentration in tea leaves; PAH4 slightly better fits low molecular weight PAHs. Several correlations between various PAHs/groups of PAHs have been identified, the strongest one (R² = 0.92) between PAH4 and EU PAH 15+1.

Biophysical Viscosity: Thermodynamic Principles of Per Capita Chemical Potentials in Human Populations

Dynamic viscosity has been used to describe molecular resistance to flow under an applied force. This study introduces the theory of biophysical viscosity, the resistance of a region to molecular flow under environmental force to define the rates of per capita anthropogenic chemical efflux into the environment. Biophysical viscosity is an important intermediate quantity, in that it can be used to calculate the chemical potentials of single molecules for individuals in a population. Nonhypothetical emission data was combined with chemical potentials of anthropogenic tracers, to demonstrate that thermodynamic quantities can be used as parameters to directly compare energies associated with individual chemical emissions across geographic regions. These results indicate that population density is not the only factor in the determination of population-level chemical efflux and that biophysical viscosity is a useful tool in determining the per capita chemical potentials of anthropogenic chemicals for environmental risk assessment.

Comparing the desorption and biodegradation of low concentrations of phenanthrene sorbed to activated carbon, biochar and compost

Carbonaceous soil amendments are applied to contaminated soils and sediments to strongly sorb hydrophobic organic contaminants (HOCs) and reduce their freely dissolved concentrations. This limits biouptake and toxicity, but also biodegradation. To investigate whether HOCs sorbed to such amendments can be degraded at all, the desorption and biodegradation of low concentrations of (14)C-labelled phenanthrene (≤5 μg L(-1)) freshly sorbed to suspensions of the pure soil amendments activated carbon (AC), biochar (charcoal) and compost were compared. Firstly, the maximum abiotic desorption of phenanthrene from soil amendment suspensions in water, minimal salts medium (MSM) or tryptic soy broth (TSB) into a dominating silicone sink were measured. Highest fractions remained sorbed to AC (84±2.3%, 87±4.1%, and 53±1.2% for water, MSM and TSB, respectively), followed by charcoal (35±2.2%, 32±1.7%, and 12±0.3%, respectively) and compost (1.3±0.21%, similar for all media). Secondly, the mineralization of phenanthrene sorbed to AC, charcoal and compost by Sphingomonas sp. 10-1 (DSM 12247) was determined. In contrast to the amounts desorbed, phenanthrene mineralization was similar for all the soil amendments at about 56±11% of the initially applied radioactivity. Furthermore, HPLC analyses showed only minor amounts (<5%) of residual phenanthrene remaining in the suspensions, indicating almost complete biodegradation. Fitting the data to a coupled desorption and biodegradation model revealed that desorption did not limit biodegradation for any of the amendments, and that degradation could proceed due to the high numbers of bacteria and/or the production of biosurfactants or biofilms. Therefore, reduced desorption of phenanthrene from AC or charcoal did not inhibit its biodegradation, which implies that under the experimental conditions these amendments can reduce freely dissolved concentration without hindering biodegradation. In contrast, phenanthrene sorbed to compost was fully desorbed and biodegraded.

Growth kinetics of some subsurface microbial strains using naphthalene as a probe contaminant

The focus of this study is the unravelling of the microbial dynamics of the biodegradation of naphthalene, a polycyclic aromatic hydrocarbon, in an aqueous-sediment matrix. The Pour plate procedure was adopted for the isolation of the microbial colonies, while the sub-culturing of the isolates was based on their cultural (biochemical) and morphological characteristics. Investigations showed that the microbial colonies consisted of the bacterial and fungal strains. The logarithmic growth curve was characterized by an initial lag phase, a rapid and exponential increase in cell biomass, a stationary phase and finally a death phase. Both strains in the presence of naphthalene-impacted basal salt medium demonstrated that the microbial growth results in an almost linear increase in biomass concentration--an indication that mass transfer from the solid phase to the liquid phase (lag phase) is limiting for growth. The kinetics of the utilization of naphthalene expressed as the growth and consumption rates indicated that all the microbial strains isolated from an indigenous soil used in this study exhibited a high metabolic affinity for naphthalene. Optimal performance was demonstrated by the bacterial strains that could use naphthalene as their sole carbon and energy source.