Polycyclic Aromatic Hydrocarbons in Sediments/Soils of the Rapidly Urbanized Lower Reaches of the River Chaohu, China

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are highly teratogenic, persistent carcinogens, and ubiquitous environmental pollutants. To determine the impact of rapid urbanization on sediment/soil PAHs, we collected 30 cm soil cores in ditch wetlands, riverine wetlands, and agricultural lands along the lower reaches of the Shiwuli River feeding Chaohu Lake, China. Ecological risk effects were evaluated by two models based upon Benzo[a]pyrene toxic equivalency (TEQ-BaP) and total toxic units (TUs). The presence of PAHs, such as BbF, BkF, InP, and BgP, that are known pollutants of concern, suggests certain ecological risks. The concentration of PAHs in the surface layer followed in the order of: ditch wetlands (617.2 ng/g average), riverine wetlands (282.1 ng/g average), agricultural lands (103.7 ng/g average). PAHs in ditch sediments were vertically distributed evenly, and PAHs in agricultural soils were concentrated in the surface soil. In riverine wetland sediments, the 2-, 3-, and 4-ring PAHs had a uniform distribution, whereas the 5- and 6-ring PAHs were concentrated in the surface soil. Redundancy analysis (RDA) explored the correlation between the environmental properties and the occurrence of PAHs. Total organic carbon (p = 0.010), percent clay (p = 0.020), and distance (p = 0.020) were the primary factors in ditch wetlands. Depth (p = 0.010) and distance (p = 0.006) were the main factors in agricultural lands. There were no significant correlations in riverine wetlands. The correlation between the distance from the built-up urban areas and pollutant concentration showed that the closer the distance, the greater the concentration of PAHs.

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“…The first four members of the group, Benzo (g,h,i) perylene and Indeno (1 The summation of the PAHs in the individual stations in the present work is lower than the observation of many authors [19,20,21]. The observation of PAHs in the present research work is at variance with the observations of [22]. In lower reaches of River Chaohu, China and [19].…”

“…The least concentrated category in all the stations was the six-membered ring. The dominance of any ring type in the sediment as observed in this work may be from the sources, origin, fate, volatility, adsoptivity and absorptivity, transformation, solubility, degradation and mobility of the PAHs [24,22]. In any environment, the dominance of 2-3 membered rings PAHs can be attributed to the length of time the PAHs were deposited [25].…”

“…Generally, the concentration of PAHs in sediment or water is attributable to the amount of dis-charge of organic matter in the environment, the presence of industries, discharge of wastes and effluents, the rate of evaporation and volatility, photo-oxidation processes, bacteria responsible for biodegradation and temperature of the environment [23,19,14]]. Another factor that may have promoted more PAHs in sediment at the Police Post and Minipiti stations over the Iwofe Jetty is reduced water movement, which allows resident time for the accumulation of PAHs in the surface sediments [22]. Another possible factor for PAHs concentration is based on the sediment water hydrodynamics that may have taken place at the three different stations.…”

Polycyclic Aromatic Hydrocarbons: Sources, Toxicity, and Remediation Approaches

“…They are strongly adsorbed onto soil particles, and therefore, the soil ecosystem becomes an ultimate sink for PAHs (Lu et al, 2011;Kuppusamy et al, 2017). Soil PAH pollution can be classified into three categories, i.e., unpolluted ( PAH < 200 ng.g −1 ), weakly polluted (PAH 200-600 ng.g −1 ), and heavily polluted (PAH > 1,000 ng.g −1 ) (Wu et al, 2019).…”

Determination of sources, spatial variability, and concentration of polycyclic aromatic hydrocarbons in surface water and sediment of Imiringi River

“…Depending on their volatility, PAHs may be transported far from their original source, ending up in various environmental compartments. Although, their main environmental sink is the organic fraction of soils and sediments [4,5,6].…”