| Phthalate esters(PAEs) compounds as plastic plasticizer, widely used in polyolefins plastics production Due to the involvement of the industry in the common agricultural plastic film, plastic merchandise has been wide utilized in the facilities of agriculture production, the ensuing environmental issues cannot be unheeded. The present study investigated fifteen types of PAEs contents in different seasons(spring, summer, autumn) and soil profiles(0-20 cm, 20-40 cm, 40-60 cm) in the northeast facility agriculture black soil region. The core findings were as follows:(1) Manipulation of seasonal variations on distribution characteristics of PAEs in the top soil of the selected area.① The 100% detection rate of fifteen types of PAEs monomer in the surface soil indicated the northeast facility agricultural black soil contaminated with persistent organic pollutants.② All selected topsoil samples were enriched in di(2-ethylhexyl) phthalate(DEHP), di-n-butyl phthalate(DBP), diethyl phthalate(DEP) and dimethyl phthalate(DMP) and their calculated mean value were assorted 1.12±0.22, 0.46±0.05, 0.36±0.04, and 0.17±0.01 mg/kg-dw, respectively; while the average concentrations of all 15 PAEs in spring, summer, and autumn were ranged between 64.08-90.51%. Therefore, the DEHP, DMP, DEP, DBP were denoted as a priority pollutant control.③Detected concentrations of the S15PAEs were significantly varied from spring to autumn and their values ranged from 1.37 to 4.90 mg/kg. The distinguished concentration of all PAEs was reported in summer and S15PAEs represented the initial rise of distribution characteristics with seasonal changes after the cut down.(2) The distribution characteristics of PAEs in the soil profile of the investigated area① Concentrations of fifteen kinds of PAEs monomer illustrated variations in the soil profiles of the experimented area. Results signified 100% detection rate of fifteen kinds of PAEs monomer in topsoil(0-20cm), while in the subsurface soil(20-40 cm, 40-60cm) just five kinds of PAEs and one kind of phthalate monomer were convalesced 100%.② The PAEs monomers having longer alkyl chain and larger molecular weight showed weak mobility from topsoil(0-20cm) to subsurface soil(40-60cm), which resulted in contents and percentage reduction symbolized as S15PAEs. On contrary PAEs monomers with short alkyl chain and smaller molecular weight evidenced relatively strong mobility from surface(0-20cm) to subsurface(40-60cm) soil. Although contents were reduced, but the decreased amplitude was lower, and the S15PAEs percentage was increased.③ So, the topsoil(0-20cm) was found enriched in PAEs and S15PAEs s were reduced from surface to subsurface soil.(3) Correlations of the ?15PAEs with physical and chemical properties of the selected soilThe?15PAEs physical and chemical properties of experiments soil showed the highly significant correlation with PAEs and organic matter, while non-significant correlation was created with PAEs, p H, porosity and moisture.(4) The variations of soil microbial community diversity in the study areaThe trend of soil microbial richness index, Shannon Wiener index and evenness index from 0-20 cm to 40-60 cm sections were showing gradually reduce,in the spring, summer, autumn three seasons.Three index were all highest in summer of the same section, and a small gap between spring and autumn. Soil bacterial diversity was identified and studied by running DGGE gel. Gel showed 20 major band recycling, which further purified by cloning, sequencing and homology comparison. The results recognized the Actinobacteria, Firmicutes and Proteobacteria as a dominant bacterial community group which was similar in all seasons and soil profiles but community structure varied. |
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