Influencing pathways of soil microbial attributes on accumulation of heavy metals in brassica (Brassica campestris L. ssp.chinensis var.utilis Tsen et Lee) leaves

Ling Xiao; Chi Zhang; Gang Wang; Dongsheng Guan; Renduo Zhang; Yujuan Chen; Jun Dai

doi:10.1016/j.envpol.2020.114215

Influencing pathways of soil microbial attributes on accumulation of heavy metals in brassica (Brassica campestris L. ssp.chinensis var.utilis Tsen et Lee) leaves

Environ Pollut. 2020 Jul:262:114215. doi: 10.1016/j.envpol.2020.114215. Epub 2020 Feb 19.

Authors

Ling Xiao¹, Chi Zhang², Gang Wang³, Dongsheng Guan⁴, Renduo Zhang⁵, Yujuan Chen⁵, Jun Dai²

Affiliations

¹ Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.
² College of Natural Resources and Environment, South China Agricultural University, Guangzhou, 510642, China.
³ School of Management, Guangdong University of Technology, Guangzhou, 510520, China.
⁴ Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China. Electronic address: eesgds@mail.sysu.edu.cn.
⁵ Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, 510275, China.

PMID: 32142975
DOI: 10.1016/j.envpol.2020.114215

Abstract

Microbial attributes have a great impact on soil heavy metal bioavailability, yet their influencing pathway on heavy metal accumulation in crop plants remains elusive. This study was aimed to analyze the influencing pathways of microbial attributes, including microbial biomass C and N (MBC and MBN), basal soil respiration (BSR) along with the activities of catalase, urease, and sucrase, on heavy metals (i.e., Cd, Cr, Cu, Ni, Pb, and Zn) accumulation by brassica leaves. Based upon a field investigation close to electroplating factory outlets, 45 pairs of soil and brassica samples were analyzed in the laboratory. Concentrations of heavy metals in brassica leaves declined with sampling distances downstream from the outlets. Redundancy analysis indicated that bioavailable concentrations of Cr, Cu, Ni, and MBC along with catalase activity were the major variables influencing heavy metal accumulation in brassica leaves and accounted for 83% of the accumulation. MBC and catalase activity accounted for 17% of the heavy metal accumulation in brassica leaves. Stepwise regression indicated that catalase activity, MBC, and BSR significantly affected heavy metal accumulation in brassica leaves. Based on structural equation modeling, the pathway coefficient of microbial activities-brassica heavy metals and the pathway coefficient of microbial biomass-brassica heavy metals are 0.122 (P < 0.05), suggesting that these microbial attributes (i.e. MBC along with catalase activities and SBR) could affect heavy metal accumulation in brassica leaves directly. The pathway coefficients of microbial activities-bioavailable heavy metals-brassica heavy metals and microbial biomass-bioavailable heavy metals-brassica heavy metal were -0.541 (P < 0.001) and 0.453 (P < 0.001), respectively, indicating that increase of microbial activities inhibited heavy metal accumulation while increase of microbial biomass promoted heavy metal accumulation, in brassica leaves. These results suggested that heavy metal bioavailability played a mediating role in the influencing pathways of soil microbial attributes on heavy metals in brassica leaves.

Keywords: Bioavailable concentration; Heavy metal; Influencing pathway; Microbial attributes; Structural equation modeling.

MeSH terms

Brassica*
Metals, Heavy / analysis*
Plant Leaves / chemistry
Soil
Soil Microbiology
Soil Pollutants / analysis*

Substances

Metals, Heavy
Soil
Soil Pollutants