Influences of Hydrosoluble and Lipophilic Rhizodeposits on Pyrene Sorption in Soil

Abstract

Plants change the behavior of pollutants in soil by rhizodeposition in the process of physiochemistry. The effects of hydrosoluble and lipophilic extracts from celery rhizodeposits on pyrene sorption were investigated. The Freundlich sorption coefficient of pyrene decreased from 1143 mg kg−1 in the bulk treatment to 670, 795, and 1030 mg kg−1 in treatments with lipophilic + hydrosoluble, hydrosoluble, and lipophilic extracts, respectively. Although both hydrosoluble and lipophilic extracts inhibited pyrene sorption, they acted at different processes on soil organic matters (SOMs) and dissolved organic matters (DOMs). The analysis of three‐dimensional fluorescence excitation‐emission matrix spectroscopy revealed that the intensity of soluble humic‐like substances increased from 5.73 in the bulk treatment to 7.74, 6.36, and 8.67 in treatments with hydrosoluble, lipophilic and hydrosoluble + lipophilic components, respectively. Images of DOMs by atomic force microscopy illustrated that the hydrosoluble extract greatly expanded the DOMs particles, while the lipophilic slightly shrank them. Moreover, the lipophilic extract dramatically softened SOMs with the glassy transition temperature declining from 50.6 ± 0.5 to 29.7 ± 2.0°C. These results not only provide insights into the mechanisms involved in pyrene sorption but also help us understand how rhizodeposition affects the pyrene bioaccessibility to some extent.

Influence of root components of celery on pyrene bioaccessibility, soil enzymes and microbial communities in pyrene and pyrene-diesel spiked soils

“…URE, INV and PHOS were responsible for the hydrolysis of urea, organic carbohydrate and organically bound phosphate, respectively (Wei et al, 2014b). They can affect the biodegradation of pyrene mainly in two ways: (1) pyrene bioaccessibility can be influenced by hydrolases through catalyzing the hydrolysis of soil organic matters, moreover, products in these processes such as phosphate can also impact pyrene adsorption/desorption (Wei et al, 2015); (2) hydrolases play an important role in the growth and function of soil microorganisms and thus affect the microbial degradation of pyrene.…”