Pervasiveness, bioaccumulation and subduing environmental health challenges posed by polycyclic aromatic hydrocarbons (PAHs): A systematic review to settle a one health strategy in Niger Delta, Nigeria

Assessment of Antibiotic Resistance Genes in Soils Polluted by Chemical and Technogenic Ways with Poly-Aromatic Hydrocarbons and Heavy Metals

Anthropogenic activities are leaving lots of chemical footprints on the soil. It alters the physiochemical characteristics of the soil thereby modifying the natural soil microbiome. The prevalence of antimicrobial-resistance microbes in polluted soil has gained attention due to its obvious public health risks. This study focused on assessing the prevalence and distribution of antibiotic-resistance genes in polluted soil ecosystems impacted by industrial enterprises in southern Russia. Metagenomic analysis was conducted on soil samples collected from polluted sites using various approaches, and the prevalence of antibiotic-resistance genes was investigated. The results revealed that efflux-encoding pump sequences were the most widely represented group of genes, while genes whose products replaced antibiotic targets were less represented. The level of soil contamination increased, and there was an increase in the total number of antibiotic-resistance genes in proteobacteria, but a decrease in actinobacteria. The study proposed an optimal mechanism for processing metagenomic data in polluted soil ecosystems, which involves mapping raw reads by the KMA method, followed by a detailed study of specific genes. The study's conclusions provide valuable insights into the prevalence and distribution of antibiotic-resistance genes in polluted soils and have been illustrated in heat maps.

A new strategy of using periphyton to simultaneously promote remediation of PAHs-contaminated soil and production of safer crops

Contaminated farmland leads to serious problems for human health through biomagnification in the soil-crop-human chain. In this paper, we have established a new soil remediation strategy using periphyton for the production of safer rice. Four representative polycyclic aromatic hydrocarbons (PAHs), including phenanthrene (Phe), pyrene (Pyr), benzo[b]fluoranthene (BbF), and benzo[a]pyrene (BaP), were chosen to generate artificially contaminated soil. Pot experiments demonstrated that in comparison with rice cultivation in polluted soil with ΣPAHs (50 mg kg-1) but without periphyton, adding periphyton decreased ΣPAHs contents in both rice roots and shoots by 98.98% and 99.76%, respectively, and soil ΣPAHs removal reached 94.19%. Subsequently, risk assessment of ΣPAHs based on toxic equivalent concentration (TEQ), pollution load index (PLI), hazard index (HI), toxic unit for PAHs mixture (TUm), and incremental lifetime cancer risk (ILCR) indicated that periphyton lowered the ecological and carcinogenicity risks of PAHs. Besides, the role of periphyton in enhancing the rice productivity was revealed. The results indicated that periphyton alleviated the oxidative stress of PAHs on rice by reducing malondialdehyde (MDA) content and increasing total antioxidant capacity (T-AOC). Periphyton reduced the toxic stress of PAHs on the soil by promoting soil carbon cycling and metabolic activities as well. Periphyton also improved the soil's physicochemical properties, such as the percentage of soil aggregate, the contents of humic substances (HSs) and nutrients, which increased rice biomass. These findings confirmed that periphyton could improve rice productivity by enhancing soil quality and health. This study provides a new eco-friendly strategy for soil remediation and simultaneously enables the production of safe crops on contaminated land.

Persistent organic pollutants and heavy metals in Ghanaian environment: a systematic review of food safety implications

Advances in industrial and technological innovations have led to significant socio-economic benefits, but with overwhelming negative impacts on the environment. These impacts include the infiltration of organic contaminants into soil, water, and air, posing a threat to the environment and public health. Polybrominated diphenyl ethers (PBDEs), heavy metals, and polycyclic aromatic hydrocarbons (PAHs) are increasingly released as waste, endangering the environment. In countries like Ghana, where regulations are weakly enforced, industrial waste is released uncontrollably, posing threats to public health, environmental integrity, and food systems. This study systematically evaluated existing literature on PBDEs, heavy metals, PAHs, and organic contaminant exposure in Ghana and proposes a roadmap for achieving food safety and protecting the environment and human health. The research identified high mobility of specific heavy metals and risks associated with PBDEs and PAHs in sediments, dumpsites, and various food items. Unregulated dumping of electronic waste with PBDEs raised environmental concerns. An integrated approach is needed to address the multifaceted impact of organic pollutants on public health and ecosystems. Urgent implementation of effective environmental management strategies and regulatory measures is crucial. The study proposed short- to mid-term priorities emphasising the need to foster collaboration and implementing global measures. The mid- to long-term strategy includes a national information surveillance system, local monitoring capacity development, and integrating land contamination controls with food safety legislation. These measures would mitigate risks, ensure sustainable practices, and improve overall food safety management in Ghana, serving as a model for regions facing similar challenges with diverse pollutants.

Inhibiting release of phenanthrene from rice-crab coculture sediments to overlying water with rice stalk biochar: Performance and mechanisms

Rice crab coculture is a new ecological agriculture model combining rice cultivation and crab farming. Current research related to rice crab coculture only focuses on production theory and technical system establishment, while ignoring the potential ecological risk of Polycyclic aromatic hydrocarbon(PAHs) in rice crab coculture sediment. In this study, rice straw was used to make rice straw biochar to explore the performance and mechanism of inhibiting release of phenanthrene(PHE) from rice-crab coculture sediments to overlying water with rice stalk biochar. The kinetic and isotherm adsorption data were best represented by the Langmuir model and pseudo-second-order model with a maximum adsorption capacity of 53.35 mg/g at 12 h contact time. The results showed that PHE was released from the rice-crab substrate to the overlying water in dissolved and particle forms as a result of bioturbation, and the PHE concentrations in dissolved and particle forms were 20.9 μg/L and 14.22 μg/L, respectively. This leads to secondary ecological risks in rice-crab co-culture systems. This is related to dissolved organic carbon(DOC) carrying the dissolved PHE and total suspended solids(TSS) carrying the particle PHE in the overlying water. Due to its large specific surface area, rice straw biochar is rich in functional groups, providing multiple hydrophobic adsorption sites. After adding rice straw biochar at 0.5 % w/w (dry weight) dose, the removal efficiency of dissolved and particulate PHE in the overlying water were 78.99 % and 42.11 %, respectively. Rice straw biochar is more competitively adsorbed PHE in the overlying water than TSS and DOC. The removal efficiency of PHE from the sediment was 52.75 %. This study confirmed that rice stalk biochar could effectively inhibit PHE migration and release in paddy sediment. It provides an environment- friendly in situ remediation method for the management of PAHs pollution from crab crops in rice fields.

Recent trends in polycyclic aromatic hydrocarbons pollution distribution and counteracting bio-remediation strategies

Polycyclic aromatic hydrocarbons (PAHs) are distributed worldwide due to long-term anthropogenic pollution sources. PAHs are recalcitrant and highly persistent in the environment due to their inherent properties, such as heterocyclic aromatic ring structures, thermostability, and hydrophobicity. They are highly toxic, carcinogenic, immunotoxic, teratogenic, and mutagenic to various life systems. This review focuses on the unique data of PAH sources, exposure routes, detection techniques, and harmful effects on the environment and human health. This review provides a comprehensive and systematic compilation of eco-friendly biological treatment solutions for PAH remediation, such as microbial remediation approaches utilizing microbial cultures. In situ and Ex situ bioremediation of PAH methods, including composting land farming, biopiles, bioreactors bioaugmentation, and phytoremediation processes, are discussed in detail, as is a summary of the factors affecting and limiting PAH bioremediation. This review provides an overview of emerging technologies that use multi-process combinatorial treatment approaches and answers to generating value-added by-products during PAH remediation.

Polycyclic Aromatic Hydrocarbons in Soil and Vegetation of Niger Delta, Nigeria: Ecological Risk Assessment

The Niger Delta, Nigeria, is noted for crude oil exploration. Whereas there seems to be a handful of data on soil polycyclic aromatic hydrocarbon (PAH) levels in this area, there is a paucity of studies that have evaluated soil and vegetation PAHs simultaneously. The present study has addressed this information gap. Fresh Panicum maximum (Jacq) (guinea grass), Pennisetum purpureum Schumach (elephant grass), Zea mays (L.) (maize), and soil samples were collected in triplicate from Choba, Khana, Trans-Amadi, Eleme, Uyo, and Yenagoa. PAHs determination was carried out using GC-MS. The percentage composition of the molecular weight distribution of PAHs, the molecular ratio of selected PAHs for identification of possible sources, and the isomeric ratio and total index of soil were evaluated. Pennisetum purpureum Schumach (elephant grass) from Uyo has the highest (10.0 mg·kg^-1) PAH while Panicum maximum (Jacq) (guinea grass) has the highest PAH (32.5 mg·kg^-1 from Khana. Zea mays (L.) (maize) from Uyo (46.04%), Pennisetum purpureum Schumach (elephant grass) from Trans-Amadi (47.7%), guinea grass from Eleme (49.2%), and elephant grass from Choba (39.9%) contained the highest percentage of high molecular weight (HMW) PAHs. Soil samples from Yenagoa (53.5%) and Khana (55.3%) showed the highest percentage of HMW PAHs. The total index ranged 0.27-12.4 in Uyo, 0.29-8.69 in Choba, 0.02-10.1 in Khana, 0.01-5.53 in Yenagoa, 0.21-9.52 in Eleme, and 0.13-8.96 in Trans-Amadi. The presence of HMW PAHs and molecular diagnostic ratios suggest PAH pollution from pyrogenic and petrogenic sources. Some soils in the Niger Delta show RQ_(NCs) values higher than 800 and require remediation to forestall ecohealth consequences.

Whole-Transcriptome Analysis on the Leaves of Rosa chinensis Jacq. under Exposure to Polycyclic Aromatic Hydrocarbons

The leaves of plants can be recommended as a cheap and sustainable environmental protection tool to mitigate PAHs with high toxicity in the ambient environment because they can serve as a reactor to remove ambient PAHs. Although previous studies have demonstrated that PAHs exhibit toxicological features, our knowledge about how ambient PAHs influence the leaves of plants is limited regarding the leaves of plants reducing ambient PAHs as a reactor. In this study, 1-year-old Rosa chinensis Jacq. with good growth potential was selected as a model plant. The leaves of Rosa chinensis Jacq. were exposed to 16 types of PAHs in the environmental concentration exposure group (0.1 μg L^-1) and high-concentration exposure group (5 μg L^-1) for seven days. In comparison, the leaves of Rosa chinensis Jacq. were exposed to de-ionized water and were chosen as the control group. During the exposure periods, the physiological parameters of leaves including, chlorophyll value, water content, temperature and nitrogen, were monitored using a chlorophyll meter. After 7 days of exposure, the leaves in the control and exposure groups were collected and used for whole-transcriptome analysis. Our results demonstrate that significant differentially expressed genes were observed in the leaves of Rosa chinensis Jacq. exposed to individual PAHs at 5 μg L^-1 compared to the control group. These differentially expressed genes were involved in seven main pathways using bioinformatic analyses. In contrast, the levels of PAHs at environmentally relevant concentrations had negligible impacts on the physiological parameters and the gene transcription levels of the leaves of Rosa chinensis Jacq. Our results may provide direct evidence to remove ambient PAHs using terrestrial trees without considering the risk of PAHs at environmentally relevant concentrations on the leaves of terrestrial plants.