Using soil amendments to reduce microcystin-LR bioaccumulation in lettuce

• Published in: Environmental pollution (1987) 2022-01, Vol.292 (Pt A), p.118354, Article 118354
• Main Authors: Cao, Qing, You, Bensheng, Liu, Weijing, Xie, Liqiang, Jiang, Weili, Cheng, Chen
• Format: Article
• Language: English
• Subjects: Bioaccumulation; Bioavailability; Human health risk; Lactuca - metabolism; Marine Toxins; Microbial community; Microcystin-LR; Microcystins - metabolism; Soil; Soil amendment
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2021.118354

Contamination of microcystins (MCs) in plant-soil system have become a serious problem worldwide, however, it remains largely unknown how to alleviate the potential risk of consuming MCs-contaminated plants. In the present study, attapulgite, biochar and peat were used as soil amendments to reduce MCs bioaccumulation in lettuce. Lettuce irrigated with 10 μg L−1 microcystin-LR (MC-LR) were growing in two different kinds of soils with or without soil amendments. Results showed that all soil amendments effectively reduced MC-LR bioaccumulation in lettuce roots and leaves. Compared with the control treatment, the MC-LR concentrations in leaves in treatments with attapulgite, biochar and peat decreased by 41.5%, 30.6%, 57.0% in soil A and 38.9%, 43.2%, 54.7% in soil B, respectively. Peat application was most effective in reducing MC-LR bioaccumulation. The decreased soil free MC-LR concentrations were positively correlated with MC-LR concentrations in lettuce, indicating decreased bioavailability of MC-LR by soil amendments. It is noteworthy that soil total MC-LR concentration in peat treatment significantly decreased by 33.3% and 29.4% in soil A and soil B, respectively, compared with the controls. According to the results from high-throughput sequencing, peat amendment increased the α-diversity of soil bacterial community and boosted the abundance of Sphingomonas and Methylobacillus (dozens of MC-degrading bacteria belong to these genera). This was in line with the results of soil total MC-LR concentration. It can be speculated that peat application directly and/or indirectly promoted microbial degradation of MC-LR in soils. This work proposed an effective way to alleviate the potential risks of MCs contamination in plant-soil system. [Display omitted] •Attapulgite, biochar and peat significantly reduced microcystin-LR uptake by lettuce.•Peat application was most effective in reducing microcystin-LR bioavailability.•Immobilization by soil amendments contributed to reduced bioaccumulation.•Peat application could enhance biodegradation of microcystin-LR.