Vertical distribution of polycyclic aromatic hydrocarbons (PAHs) in Hunpu wastewater-irrigated area in northeast China under different land use patterns

Abstract

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were determined in groundwater and soil profiles from upland field and paddy field in the Hunpu wastewater-irrigated area of northeast China. In the study area, the peak concentrations of total PAHs were within or just below the topsoil, and the contents decline with depth at various trend verified by the Spearman's rank correlation test. The total PAH concentrations in upland soil layers ranged from 46.8 to 2,373.0 microg/kg (dry wt.), while the concentrations in paddy soil layers ranged from 23.1 to 1,179.1 microg/kg (dry wt.). The 16 priority PAHs were all detected in the analyzed soil samples, and naphthalene (Nap), phenanthrene (Phe), fluoranthene (Fla), chrysene (Chr), and benzo[a]pyrene (Bap) were selected for further study in terms of their vertical distributions. The concentrations of both total and individual PAHs in upland soil were generally higher than those in the corresponding layers of paddy soil. The concentrations of total and individual PAH were notably different between the corresponding horizons in upland and paddy soil were probably attribute to the different sources and properties of the PAHs and soil; different methods of soil tillage and plant growing. Special PAH compound ratios, such as phenanthrene/anthracene, fluoranthene/pyrene, LMW/HMW, and parent PAH ratios (Ant/178, Fla/202, BaA/228, and Ilp/276) were used to identify the source of soil PAHs. The data suggests that the possible sources of PAHs in the Hunpu wastewater-irrigation area are the incomplete combustion of coal, petroleum and crude oil, automobile exhausts. These sources lead to pollution of the soil and groundwater by wet/dry deposition and vertical downward migration.

Distribution and sources of petroleum-hydrocarbon in soil profiles of the Hunpu wastewater-irrigated area, China's northeast

“…In Tianjin, the hydrocarbon content in most samples was within 20 μg g − 1 , and the maximum occurrence at the suburb area was 80 μg g − 1 . The contents decreased with depth, which was identical to the distribution of PAHs in Hunpu (Bu et al, 2007;Xiao et al, 2008). The diesel range organics in soil varied from 0.2 to 4200 μg g − 1 at the three oil release sites at Big South Fork National River and Recreation Area, Tennessee and Kentucky, where the concentration of deep layer was higher compared with that of the shallow layer at some points (Williams et al, 2006).…”

“…The Xihe River is the major drainage channel of industrial effluent and municipal sewage of Shenyang City, where many petrochemical plants exist and the use of petroleum products is common (Xiao et al, 2008). The situation resulted in the excessive petroleum hydrocarbon contamination of the Xihe River and its riverbank groundwater (Song et al, 2004;Song et al, 2007), making it the most polluted river of Shenyang and a pollution source of the Hunhe River.…”

Effects of fertigation with purified urban wastewater on soil and pepper plant (Capsicum annuum L.) production, fruit quality and pollutant contents

“…As with the case of heavy metals in the soil, the results found in the bibliography show accumulation of PAH in soils irrigated with wastewater (Tao et al, 2004;Xiao et al, 2008). There are marked differences between this study and those cited because in the latter studies the soils were influenced by atmospheric contamination from the urban area as well as industry in the area which added PAH to the soil from the air.…”

Impact of reclaimed water irrigation on PAHs in agricultural soil and groundwater

“…The sum of 16 PAHs in surface were obviously lower than those present in wasterwater irrigation areas in Beijing, Tianjin and Liaoning [9][10] .This was because the quality of reclaimed water was much better than wasterwater. The vertical distribution of total PAHs concentrations in profiles was shown in FIGURE 1.…”