Assessing soil metal concentrations, microbial biomasses and enzymatic activities in aerial limed lands impacted by mining pollution in the City of Greater Sudbury

Abstract

Mining pollution in the City of Greater Sudbury led to acid rain and metal contamination of soils, which ultimately caused massive environmental and ecological damage. Soil liming, in addition to tree planting and fertilizing, have been the techniques used to restore these damaged ecosystems. The objective of this study was to assess the effects of aerial liming on pH, and metal contamination microbial biomass and abundance, enzymatic activities. Soil pH was higher in limed sites compared to unlimed at Baby Lake and Wahnapitae sites but not at HWY 80 N site. Organic matter was higher in limed areas compared to reference site only at Baby Lake site. Metal concentrations of iron (Fe) and arsenic (As) were significantly higher at the unlimed sites. Enzyme assays and Phospholipid fatty acid (PLFA) analysis were used to assess three limed soil sites and their adjacent unlimed soils. β-N-acetylglucosaminidase (BG), aryl sulfatase (AS), and glycine aminopeptidase (GAP) activity levels were significantly increased in the limed soils compared to the unlimed soils. Total microbial biomasses, gram negative bacterial, fungal, and eukaryotic biomasses were all increased in the limed soils compared to the unlimed soils. Microbial biomass ratios of gram negative/gram positive, saturated/unsaturated, and mono/poly microorganisms were all significantly increased at the unlimed sites compared to the limed sites, indicating that the unlimed sites are still undergoing environmental stresses.