Purification Effects on β-HCH Removal and Bacterial Community Differences of Vertical-Flow Constructed Wetlands with Different Vegetation Plantations

Abstract

This study aimed to investigate the removal of β-hexachlorocyclohexane (β-HCH) at realistic concentration levels (10 µg/L) in different plant species in constructed wetlands (Acorus calamus, Canna indica, Thalia dealbata, and Pontederia cordata) and the structure of the rhizosphere microbial community response of each group during summer and winter. Results showed that all groups of constructed wetlands had very good decontamination efficiency against β-HCH in water (90.86–98.17%). The species that most efficiently purified β-HCH in water was A. calamus in summer (98.17%) and C. indica in winter (96.64%). Substrate sorption was found to be the major pathway for β-HCH removal from water in the constructed wetlands. The ability of the wetland plants to absorb and purify β-HCH was limited, and C. indica had the strongest absorptive capacity among the four plant species. The mean β-HCH removal from the matrix of the planted plants increased by 5.8% compared with that of the control treatment (unplanted plants). The average β-HCH content in the plant rhizosphere substrate was 4.15 µg/kg lower than that in the non-rhizosphere substrate. High-throughput sequencing analysis revealed significant differences (P < 0.05) in the Chao1 and ACE indices of microbes in the substrate of four wetlands during summer and winter. At the genus level, the constructed wetlands with vegetation plantations showed higher microbial abundance than the constructed wetlands without vegetation plantations. In winter, the bacterial community structure of each constructed wetland was quite different, but no dominant flora in the bacterial community structure obviously changed. In summer, the bacterial community structure at the same stage was relatively small. The abundance of Actinobacteria and Sphingomonas remarkably increased over time in summer.

Assessing HCH isomer uptake in Alnus glutinosa: implications for phytoremediation and microbial response

“…In contrast, the removal of 64.58% of α-HCH is consistent with the findings of the study by Liu et al 66 , where 47.3% was removed under hydroponic conditions in the presence of wheat. Chen et al 67 investigated the removal of β-HCH at realistic concentration levels in different plant species in constructed wetlands, including Acorus calamus, Canna indica, Thalia dealbata, and Pontederia cordata , and found decontamination efficiency against β-HCH in water ranging from 90.86 to 98.17%. Kidd et al 40 designed a greenhouse experiment to evaluate HCH dissipation and microbial parameters among rhizosphere and bulk soil of two contrasting plants, Cytisus striatus and Holcus lanatus , demonstrating the potential of these plant species in the degradative removal of α-HCH from the soil.…”

Degradation Characteristics and Remediation Ability of Contaminated Soils by Using β-HCH Degrading Bacteria

“…GC/ECD chromatographic conditions [24]: The content of β-HCH in the sample was subjected to the GC-ECD analysis after solid phase extraction. The sample was injected by an autosampler with a splitting ratio of 10:1 and an injection volume of 0.8 µL.…”

Potential of Canna indica in Constructed Wetlands for Wastewater Treatment: A Review

“…Canna indica performed better in a study investigating the removal of β-hexachlorocyclohexane (β-HCH) from water in the winter, with a removal efficiency of 96.64%. The main mechanism for removing β-HCH from water in the CW was determined to be substrate sorption [104]. Single and binary combinations of penta-chlorophenols (PCP) and trichlorophenols (TCP) were tested for competitive adsorption and phytotoxicity on Canna indica as the phytoremediator.…”