Ecological risk and sources of metals in open‐burned grasses in Guinea Savanna of Nigeria

Abstract

Heavy metals in particulate emissions released into the atmosphere from open burning of grasses pose considerable danger to human health and environment. This study investigated the ecological risks and sources of heavy metals from burned grass emissions. Particulates resulting from laboratory‐simulated open burning of 40 species of grasses common in Nigeria were analyzed for heavy metals using energy‐dispersive X‐ray fluorescence (EDXRF). Highest metal concentrations were observed in Digitaria nuda for Cr, Cu, Rb, Zr, and Ni at 105, 35, 95, 70, and 40 mg/kg dry weight, respectively. The pollution assessment with enrichment factor, geo‐accumulation index, and contamination factor showed that Panicum repens and Sorghum bicolor were heavily contaminated with Pb. Pearson correlation analysis indicated strong positive relationship between Cu, Ni, Rb, Cr, and Zr, implying a same pollution source. Principal component analysis was used to identify possible pollutant sources, and 36.29% of the total variance was observed in factor 1. High loading of Cu (0.987), Ni (0.987), Rb (0.986), Cr (0.984), and Zr (0.839) were contributed by metal industries and crustal origin. This study revealed the extent of environmental pollution by heavy metals during open burning of grasses particularly from anthropogenic sources.