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Pollution levels, sources and health risks of polycyclic aromatic hydrocarbons in vegetable soils in suburban Changchun City

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants.As cities expand, suburban environments are increasingly polluted by PAHs, posing a huge potential risk to suburban agriculture.Therefore, we investigated the pollution levels, sources and risks of soil PAHs in vegetable fields in Changchun suburbs of Northeast China.The total concentrations of 16 PAHs (Σ16PAHs) in soil ranged from 2338.2 to 15200 ng g-1 (average 6778.1 ng g-1), significantly higher than most other cities.High molecular weight PAHs are the main components, accounting for more than 85.63% of all PAHs.Seven potential carcinogenic PAHs accounted for 56.96% of Σ16PAHs.Source apportionment results based on PAH isomer ratio and principal component analysis indicated that PAHs were mainly derived from pyrolysis sources, such as biomass/coal combustion, transportation emissions, and petroleum.Ecological risk values ​​for PAHs ranged between low impact range (ERL) and medium impact range (ERM) and may occasionally cause ecological risk in suburban areas.According to the incremental lifetime cancer risk assessment results, the health risk of the exposed population is at an acceptable level, and skin contact and ingestion are the main routes of exposure.China chemical product hot selling supply bmk cas 5449-12-7,pmk 28578-16-7,71368-80-4,30123-17-2.
In recent decades, rapid industrialization and urbanization have exacerbated environmental pollution, especially by persistent organic pollutants (POPs) with high toxicity, persistence, bioaccumulation, and long-distance transport.Polycyclic aromatic hydrocarbons (PAHs) are typical POPs derived from natural and anthropogenic sources.Anthropogenic sources of PAHs are the main and widespread sources, such as mobile sources, domestic combustion sources and industrial sources, accounting for 50.5%, 41.6% and 7.9% of total PAHs emissions, respectively1.PAHs are easily adsorbed in suspended particles and aerosols, and can enter soil through wet and dry deposition.Due to their hydrophobicity and stability, PAHs can be adsorbed by soil organic matter and become toxic to soil microorganisms and plants, thereby affecting soil ecological functions3.Soil-to-plant transfer is the main route of human exposure to soil PAHs.PAHs in soil can be taken up by roots and transferred to plant tissues, and then accumulated in the human body through the food chain.Studies have shown that PAHs can cause pathological changes in human organs, such as the respiratory tract, kidneys, liver, and even the endocrine, reproductive and nervous systems5,6,7.
Vegetables contain a variety of nutrients, such as vitamins, proteins, minerals and carbohydrates, which play an important role in the human diet.Because vegetables can be produced in small or pilot fields and have a short growth cycle, it is very common to grow vegetables in suburban areas8,9.The surge of urban population has promoted the rapid development of suburbs, and changes in the industrial structure of suburban activities and living environment have had a huge impact on agricultural production10.Urban expansion has led to the occupation of a large amount of cultivated land on the outskirts of the city for the relocation of factories or the construction of roads and new residential quarters, making the remaining vegetable fields closer to pollution sources such as factories, roads, and residential areas, or even surrounded by buildings11.PAHs can enter rural agricultural soils from different sources, leading to the accumulation of pollutants, affecting soil quality and human health5.

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As the central city of the Northeast Asian economic circle, Changchun plays an important role in economic growth, urbanization, and international trade.In recent years, with the continuous development of urbanization, the land use pattern of Changchun suburbs has undergone significant changes.According to the 2010-2020 Statistical Yearbook of Changchun City, the urban area in 2019 was 7,293 square kilometers, an increase of about 1.5 times compared with 2009.In order to meet the living needs of the rapidly growing urban population, a large number of residential quarters and supporting thermal power plants or heating facilities have been built in the suburbs, so that the suburban living areas and the original industrial enterprise areas are staggered or staggered.At the same time, private cars have become the main means of transportation due to their distance from the city center.These mobile sources, civil combustion sources and industrial sources formed a comprehensive pollution effect in the suburbs, resulting in a large accumulation of PAHs in the soil, especially in the suburban vegetable fields with high ecological risks.Early studies on soil pollutants in vegetable fields in suburban Changchun mainly focused on heavy metals (HMs) and organochlorine pesticides (OCPs)12,13,14, while studies on PAHs were scarce.The comprehensive pollution level of PAHs in agricultural soils along the main roads in Changchun City was evaluated, and it was found that more than 90% of the sampling points were above the light pollution level15.In addition, nearly 30% of the samples were at an ecological risk level of “highly severe” or more severe16.Similar results were obtained in snow and indoor dust17,18.The above results indicate that the potential ecological risks of PAHs are prevalent in the suburbs of Changchun, but the overall quality of the suburban vegetable plots remains unclear.Therefore, the identification of PAH contamination levels, sources and risks in suburban vegetable soils can help to establish effective risk management.To this end, the content of PAHs and their potential sources in vegetable field soils in suburban Changchun were investigated, and toxicological risks were identified.

The 16 USEPA priority PAHs analyzed in soil samples were: naphthalene (Nap), acenaphthene (Acy), acenaphthene (Ace), fluorene (Flu), phenanthrene (Phe), anthracene (Ant), fluoranthene (Fla), pyrene (Pyr) , Benzo[a]anthracene (BaA), Pyrene (Chr), Benzo[b]fluoranthene (BbF), Benzo[k]fluoranthene (BkF), Benzo[a]pyrene (BaP) , indeno[1,2,3-cd]pyrene (Inp), dibenzo[a,h]anthracene (Daha) and benzo[g,h,i]perylene (Bghip)19.Ultrasonic extraction and purification procedures for PAHs followed previous methods15,20.All PAH concentrations are reported on a dry weight basis.
Extract 2.0 g of soil samples (to measure moisture content) mixed with 5 g of anhydrous sodium sulfate and 15 mL of solvent (n-hexane:acetone = 1:1, v/v) in a centrifuge tube, and ultrasonically extracted for 15 min.Extracts were collected in round bottom flasks after centrifugation at 4500 rpm for 10 minutes.The extraction process was performed 3 times and a total of 45 mL of extract was obtained.The extracts were rotary evaporated to near dryness at 40 °C and redissolved in 2 mL of n-hexane.
Purification The concentrated extract was purified by a Florisil column and eluted with 5 mL of acetone/n-hexane mixture (V:V = 1:9).The eluate was concentrated to near dryness and diluted to 2 mL with dichloromethane.


Post time: Nov-14-2022