Uptake and distributions of polycyclic aromatic hydrocarbons in cultivated plants around an E-waste disposal site in Southern China

Uptake of polycyclic aromatic hydrocarbons (PAHs) from PAH-contaminated soils to carrots and Chinese cabbages under the greenhouse and field conditions

Polycyclic aromatic hydrocarbons (PAHs) with the properties of structural stability, semi-volatility, and hydrophobicity are toxic and persistent in environments; thus, their transport and fate in agroecosystems is essential for reducing PAH accumulation in the edible parts of crops. Here, we cultivated cabbages (Brassica pekinensis L.) and carrots (Daucus carota L.) in PAH-contaminated soils under the greenhouse and field conditions. After harvesting, we observed a 9.5-46% reduction in soil ∑PAH concentrations. There were 37% of bioconcentration factors (BCFbs) > 1 and 93% of translocation factors (TFab) > 1, while low-molecular-weight (LMW) PAHs had higher BCFbs than high-molecular-weight (HMW) PAHs. The PAH concentrations showed significant and positive correlations among soils, the belowground parts, and the aboveground parts. The toxicity equivalent concentration (TEQBaP) followed the order of cabbage (greenhouse) > cabbage (field) > carrot (greenhouse) > carrot (field), suggesting potentially higher health risks in cabbage relative to carrot and vegetables under the greenhouse relative to field condition. Our study suggested growing carrots under field conditions as a management strategy for reducing the risks of vegetables grown in PAH-contaminated soils.

Lagging pollution of polycyclic aromatic hydrocarbons in the rebuilt e-waste site: From the perspective of characteristics, sources, and risk assessment

Little information is known regarding how the lagged pollution of polycyclic aromatic hydrocarbon (PAH) influenced the environment and human health after an e-waste dismantling site was rebuilt. This study investigated the characteristics, sources, and risk assessment of PAHs in a rebuilt e-waste site and its surrounding farmland by analyzing the samples of soil, dust, water, and vegetable. Concentrations of PAHs in soil, vegetable and water in the rebuilt site were relatively higher than in its surrounding farmland. The concentrations in surface soils, soil columns, dust, vegetables, and water varied from 55.4 to 3990 ng g-1, 1.65 to 5060 ng g-1, 2190 to 2420 ng g-1, 2670 to 10,300 ng g-1, and 46.8 to 110 μg L-1 in the e-waste site, respectively. On the farmland, PAH concentrations in surface soils, vegetables, and water ranged from 41.5 to 2760 ng g-1, 506 to 7640 ng g-1, and 56.6 to 89.2 μg L-1, respectively. A higher proportion of high-molecular-weight PAHs (HMW-PAHs) appeared in all multimedia compared with low-molecular-weight PAHs (LMW-PAHs). Diagnostic ratio together with positive matrix factorization (PMF) revealed that vehicle emission was the primary source in this area, and the activity of e-waste disposal was another important source in the rebuilt e-waste site. Based on the deterministic health risks, people working in the reconstructed e-waste site were exposed to low risks, whereas the residents living near the surrounding farmland were exposed to low risk. Sensitivity analyses indicated that exposure frequency and PAH concentrations were the main factors that influenced exposure risk. This study provides valuable insight into the comprehension of the lagging pollution effects of PAH on the environment and human health after the e-waste site was rebuilt.

Accumulation of Atmospheric PAHs in White Mustard - Can the Seeds Be Affected?

Traffic-related particulate matter emissions have been considerably reduced due to stringent regulations in Europe. However, emission of diesel-powered vehicles still poses a significant environmental threat, affecting rural ecosystems and agriculture. Several studies have reported that polycyclic aromatic hydrocarbons (PAHs), a group of potentially toxic organic compounds, can accumulate in crops and vegetables. In our study, white mustard (Sinapis alba L.) plants were experimentally treated with an extract of diesel exhaust. PAH concentrations were measured in the different plant compartments (stems, leaves and seeds), bioconcentration factors (BCFs) were also calculated. Significant accumulation was measured in the leaves and seeds, stems showed lower accumulation potential. All plant matrices showed high tendency to accumulate higher molecular weight PAHs, BCF was the highest in the 6-ring group. The fact that considerable accumulation was experienced in the seeds might show the risk of cultivating crops nearby roads highly impacted by traffic-related emissions.

Distribution and transfer rules of polycyclic aromatic hydrocarbons in soil-wheat ecosystems in China

The translocation and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) in the soil-crop system have important implications for the fate of PAHs and human health. This study summarized the concentrations of 16 priority PAHs in the soils and various parts of mature winter wheat in China, sourced from a screening of previous literature in English and Chinese databases. The study analyzes the distribution characteristics, transfer patterns, and human health risks of PAHs in sites studied in Shaanxi, Henan, and Shandong provinces. The results showed that the concentrations of Σ16 PAHs in the rhizosphere soil of wheat ranged from 10.30 to 893.68 ng/g, in descending order of Shaanxi > Henan > average > Shandong. In sites with mild to moderate contamination (200 < Σ16 PAHs < 600 ng/g; i.e., Henan and Shaanxi), the concentration of Σ16 PAHs in the roots was higher than that in the stems or the grains, while in contamination-free sites (Σ16 PAHs < 200 ng/g; i.e., Shandong), the highest concentration of Σ16 PAHs was found in the stems. Generally, the concentrations of PAHs increased in the order of roots-stems-grains. The predominant PAHs in each part of wheat were 2- or 3-ring compounds, with five- or six-ring PAHs being more prevalent in wheat from Shanghe, Shandong. The bioaccumulation factors of different wheat parts from Shaanxi and Henan were consistently smaller than 1, and low- and medium-ring (2-4 rings) PAHs had bigger bioconcentration factors than high-ring (5-6 rings) PAHs. However, the accumulation of PAHs in the aboveground parts of wheat was larger than that in the underground parts of the Shandong sites. The linear regression relationship between the octanol-water partition coefficient and root concentration factor (RCF) of PAHs reflected that low and medium-ring PAHs were more easily absorbed by wheat roots than high-ring PAHs in Shaanxi and Henan. Our assessment of the health risks of oral wheat intake in adults and children by the incremental lifetime cancer risk (ILCR) model found a potential carcinogenic risk for both age groups in each province, with higher risks in adults than in children.

A review of various strategies in e-waste management in line with circular economics

Waste management of electrical and electronic equipment has become a key challenge for electronics manufacturers due to globalization and the rapid expansion of information technology. As the volume of e-waste grows, legal departments lack the infrastructure, technology, and ability to collect and manage it environmentally soundly. Government laws, economic reasons, and social issues are important considerations in e-waste management. The circular economy concept is built on reusing and recycling goods and resources. A novel idea called the circular economy might prevent the negative consequences brought on by the exploitation and processing of natural resources while also having good effects such as lowering the demand for raw materials, cutting down on the use of fundamental resources, and creating jobs. To demonstrate the significance of policy implementation, the necessity for technology, and the need for societal awareness to build a sustainable and circular economy, the study intends to showcase international best practices in e-waste management. This study uses circular economy participatory implementation methods to provide a variety of possible approaches to assist decision-makers in e-waste management. The purpose of this article is to review the most accepted methods for e-waste management to emphasize the importance of implementing policies, technology requirements, and social awareness in creating a circular economy. To conclude, this paper highlights the necessity of a common legal framework, reform of the informal sector, the responsibility of different stakeholders, and entrepreneurial perspectives.

Vicia faba seed: a bioindicator of phytotoxicity, genotoxicity, and cytotoxicity of light crude oil

Crude oil contamination is a serious threat to the environment and human health as it can contaminate food chains. Therefore, it is necessary to find efficient tests to monitor soils for crude oil contamination. The present study investigates the efficacy of Vicia faba seeds for monitoring contaminated soils with light crude oil. Vicia faba seeds were planted in 0 (control), 1, 2, and 4 percentages (weight percentage) light crude oil-contaminated soils. The seed germination and root length were measured to evaluate phytotoxicity, while the mitotic index, chromosome aberrations, and micronucleus formation in the root tip cells were examined for cytotoxicity and genotoxicity tests. The results showed that light crude oil had toxic effects on Vicia faba growth characteristics, even at 1% contamination. The phytotoxicity assay showed that crude oil reduced seed germination and root length by 45% and 61.67%, respectively. In contrast, cellular observations indicated an increase in mitotic index, chromosome aberrations, and micronucleus formation up to 3, 3.59, and 5.6 times, respectively, compared to the control. The light crude oil at 4% induced the simultaneous occurrence of nuclear bud, polyploidy, and micronucleus that may be considered as severe clastogenic and aneugenic effects. Accordingly, Vicia faba can be considered a reliable living system for monitoring light crude oil pollution in soils, even at low concentrations.

Effects of arbuscular mycorrhizal inoculation on the phytoremediation of PAH-contaminated soil: A meta-analysis

Inoculation with arbuscular mycorrhizal (AM) fungi can accelerate the phytoremediation process by increasing plant biomass and improving soil physicochemical and biological characteristics. However, a quantitative, data-based conclusion is yet to be derived on the roles of AM fungi in remediating soils polluted by polycyclic aromatic hydrocarbons (PAHs), and the impact factors are unclear. To address these issues, we performed a meta-analysis of 45 articles to estimate the effects of AM inoculation on the phytoremediation of soils polluted by PAHs and to examine the influence of experimental conditions on these effects. Our results showed that AM inoculation significantly decreased the residual soil PAHs concentration at all PAHs levels, and the largest effect of AM treatment was 48.5% compared to the non-mycorrhizal treatment. This should be attributed to increased plant growth and PAHs uptake, and soil biological activity in the rhizosphere induced by AM symbionts. Compared to the non-mycorrhizal treatment, the largest AM effects on the total plant biomass, root PAHs concentration, shoot PAHs concentration, soil bacterial biomass, soil catalase activity, and soil polyphenol oxidase activity were 51.7%, 565%, 53.1%, 141%, 100% and 51.9%, respectively. Although these effects on the above mentioned parameters varied with AM fungi (genus, species, and inoculation mode), soil PAHs (source, concentration, and type), plant type (dicots and monocots), and experimental conditions (experimental duration, soil sterilization and additional factors), few negative AM effects were observed. This study confirmed the feasibility of using AM fungi to enhance the phytoremediation of PAHs-contaminated soil.

Elevated urbanization-driven plant accumulation and human intake risks of polycyclic aromatic hydrocarbons in crops of peri-urban farmlands

As an ubiquitous carcinogen, polycyclic aromatic hydrocarbons (PAHs) are closely related to anthropogenic activities. The process of urbanization leads to the spatial interlacing of farmlands and urbanized zones. However, field evidence on the influence of urbanization on the accumulation of PAHs in crops of peri-urban farmlands is lacking. This study comparatively investigated the urbanization-driven levels, compositions, and sources of PAHs in 120 paired plant and soil samples collected from the Yangtze River Delta in China and their species-specific human intake risks. The concentrations of PAHs in crops and soils in the peri-urban areas were 2407.92 ng g^-1 and 546.64 ng g^-1, respectively, which are significantly higher than those in the rural areas. The PAHs in the root were highly relevant to those in the soils (R² = 0.63, p < 0.01), and the root bioconcentration factors were higher than 1.0, implying the contributions of root uptake to plant accumulations. However, the translocation factors in the peri-urban areas (1.57 ± 0.33) were higher than those in the rural areas (1.19 ± 0.14), indicating the enhanced influence through gaseous absorption. For the congeners, the 2- to 3-ring PAHs showed a higher plant accumulation potential than the 4- to 6-ring PAHs. Principal component analysis show that the PAHs in the peri-urban plants predominantly resulted from urbanization parameters, such as coal combustion, vehicle emissions, and biomass burning. The mean values of estimated dietary intake of PAHs from the consumption of peri-urban and rural crops were 9116 ng day^-1 and 6601.83 ng day^-1, respectively. The intake risks of different crops followed the order rice > cabbage > carrot > pea. Given the significant input of PAHs from urban to farmland, the influence of many anthropogenic pollutants arising from rapid urbanization should be considered when assessing the agricultural food safety.

Plant contribution to the remediation of PAH-contaminated soil of Dagang Oilfield by Fire Phoenix

Pot experiments were conducted to evaluate plant contribution during remediation of the polycyclic aromatic hydrocarbons (PAH)-contaminated soil of Dagang Oilfield by Fire Phoenix (a mixture of Festuca L.). The results showed that Fire Phoenix could grow in soil contaminated by high and low concentrations of PAHs. After being planted for 150 days, the total removal rate of six PAHs in the high and low PAH concentrations was 80.36% and 79.79%, significantly higher than the 58.79% and 53.29% of the unplanted control group, respectively. Thus, Fire Phoenix can effectively repair the soil contaminated by different concentrations of PAHs. In high concentrations of PAHs, the results indicated a positive linear relationship between PAH absorption in tissues of Fire Phoenix and the growth time in the early stage. In contrast, the contents of PAHs were just slightly increased in the late period of plant growth. The main factor for the dissipation of PAHs was plant-promoted biodegradation (99.04%-99.93%), suggesting a low contribution of PAH uptake and transformation (0.07%-0.96%). The results revealed that Fire Phoenix did not remove the PAHs in the soil by accumulation but promoted PAH dissipation in the soil by stimulating the microbial metabolism in the rhizosphere.

Soil concentrations, compositional profiles, sources and bioavailability of polychlorinated dibenzo dioxins/furans, polychlorinated biphenyls and polycyclic aromatic hydrocarbons in open municipal dumpsites of Chennai city, India

Several studies have reported the release of halogenated persistent organic pollutants (POPs) and polycyclic aromatic hydrocarbons (PAHs) associated with open burning of municipal solid waste. Considering soil as a sink for such organic contaminants, we conducted an in-depth study on the surface soil concentrations of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs), polychlorinated biphenyls (PCBs) and sixteen USEPA enlisted PAHs collected from thirteen zones of the two major municipal dumpsites, Kodungaiyur dumpsite (KDS) and Perungudi dumpsite (PDS) of Chennai city. Indigenous microbes from dumpsite soil samples were isolated and identified based on 16S rRNA sequencing and phylogenetic analysis. Using indigenous microbes, we have elucidated the bioavailability of the targeted organic pollutants for each site.Range of Σ₁₇PCDD/Fs, Σ₂₅PCBs and ∑₁₆PAHs varied between 3.96-612 pg/g (96.0 pg/g; median), ND-182 ng/g (6.35 ng/g; median) and 0.62-3649 ng/g (64.3 ng/g; median), respectively. All the dumpsite samples showed bioavailability for POPs and PAHs. Toxicity equivalent values (TEQs) associated with dioxin-like PCBs and PCDD/Fs from the zones where dumped municipal solid wastes were collected from electronic-waste/IT-corridor/port areas and toxic PAHs from the zone receiving wastes from the industrial corridor of the city were higher than the soil permissible limit prescribed by the World Health Organization.