Monitoring air pollution based on plant fertility around a steel company in Santa Cruz, Rio de Janeiro, Brazil

Abstract

Introduction:Since 2010 a steel company was stablished in Santa Cruz, RJ, with potential emission of heavy metals in the atmosphere. On that year, silver rains occurred in the area arising concerns on possible environmental impact. Plant bioassay have been widely employed to monitor air pollution in areas with no conventional air pollution monitoring system, due to its simplicity, low cost and high sensitivity.Aim:to evaluate air pollution based on plant fertility around a steel company and control areas in Santa Cruz, Rio de Janeiro, Brazil.Methods: Pollen abortion essay was preceded using wild local plant (Bauhinia forticata) from 20 exposed sites, around a steel company located in Santa Cruz, RJ (2.2 to 8.34 km distant). All sampling sites were located down-wind from the emission sites and sample collections was proceeded during dried season. Control samples collected from 7 sites, was divided in two groups: collected in dried season (16.3 to 16.5km distant); collected in raining season (51.8 to 59.4km distant). At least 10 plants of each site were randomly collected. From each sample, 3000 pollen grains were evaluated. Abortive grains were analyzed using a microscope under 400-fold magnification.Results:Strongest effects on pollen abortion were observed close to the steel company (1.15 to 9.26-fold, compared to dried season control; and 1.49 to 9.13-fold compared to raining season control). Mean abortion pollen was statistically higher on exposed areas (sites 1, 2, 5, 7, 8, 10, 11, 13, 14, 18, 19, 20, 22) as compared to non-exposed areas, regardless the season of collection (Dried season:p<0.05;Raining season: p<0.05).Conclusion:Areas surrounding steel companies are at higher concentration of toxic elements, leading to a greater impact on the fertility of wild plants, independently of the season of collections. Using pollen abortion rates as an air monitoring system could be a simple alternative of environmental screening method in areas with limited technology.