Characterizing the Variation of Dissolvable PAHs in Receiving Water in a Reclaimed Water Irrigation Region

Abstract

Long-term wastewater and reclaimed water irrigation systems constitute the major processes in local water circulation, which concomitantly introduce plenty of undesirable substances that can threaten water quality, ecosystem functions and human health. At the Southeast Reclaimed Water Irrigation Region (SRWIR) of Beijing, wastewater irrigation was adopted from 1969 to 2002, and second-treated effluents (reclaimed water) has been used thereafter. Polycyclic aromatic hydrocarbons (PAHs) were the most ubiquitously detected contaminant in wastewater and reclaimed water and are reported to be carcinogenic. Hence, we measured the concentrations of dissolved sixteen United States Environmental Protection Agency (USEPA) priority PAHs in surface water and groundwater at the SRWIR to characterize their spatial and temporal variations, and to clarify the role of reclaimed water to natural water. The concentration of 16 individual PAHs in reclaimed water, rivers and groundwater varied from 339.4 to 636.2 ng/L, 359.1 to 3435.0 ng/L and 216.5 to 488,205.2 ng/L, respectively. The lower aromatic rings of PAHs prevailed in aquatic environments rather than the higher ones. Thereinto, naphthalene was the predominant isomer within the highest concentration reached to 486,600 μg/L. The groundwater samples had higher PAHs concentrations at Tongzhou district which attributed to the higher vulnerability of aquifer. Additionally, strong correlations between PAHs and total nitrogen, nitrate, dissolved oxygen and electrical conductivity suggested those potential factors affecting the photo degradation and/or biodegradation of PAHs. The relationship identified between PAHs concentrations and physical and chemical indices would help us to enhance the understanding migration and transformation of PAHs spatially and temporally, enable us to assess the potential risks of the environmental pollutants to aquatic organisms and human water supplies.

Restoration of soils contaminated with PAHs by the mixture of zeolite composites mixed with exogenous organic matter and mineral salts

“…A significant positive correlation between soil pH H2O /pH KCl and PAHs suggested that the soil’s pH was a key factor in the soil PAHs levels. The statistical negative correlation of all rings PAHs with EC suggest that this factor also indirectly affects the degradation of PAHs in soils 45 . The same results were observed for the application of zeolite composites mixed with leonardite 29 .…”

New Trends in Bioremediation Technologies Toward Environment-Friendly Society: A Mini-Review

“…These PAHs' physiochemical and toxic properties raise a significant concern over their impact on soil and groundwater contamination (Wang et al, 2009 ). Moreover, several reports showed evidence of PAH contamination in different soil and groundwater sources (Sushkova et al, 2018 ; Haleyur et al, 2019 ; Lu et al, 2019 ; Liang et al, 2020 ; Pacwa-Płociniczak et al, 2020 ; Picariello et al, 2020 ; Wang Y. et al, 2020 ; Wolf et al, 2020 ; Ambade et al, 2021a , b ; Qiao et al, 2021 ). Therefore, the PAH contamination problem requires more research in this direction using chemical cleavage.…”