Environmental risk assessment of a metal-contaminated area in the Tropics. Tier I: screening phase

Abstract

Purpose The present study presents data on the screening phase (tier 1) of a site-specific ecological risk assessment in a former smelter area heavily contaminated with metals (Santo Amaro, Bahia, Brazil). Joining information from three lines of evidence (LoE), chemical, ecotoxicological, and ecological, integrated risk values were calculated to rank sites within the area and identify those that may need further investigation in tier 2. Materials and methods Eleven points were selected up to 1,000 m from the smelter. Three reference points were 3 and 9 km away from the area. Risk values for the chemical LoE were derived from calculating the toxic pressure based on total metal concentrations. Those for the ecotoxicological LoE were based on avoidance (Folsomia candida and Eisenia andrei) and eluate tests (Daphnia magna acute test and Microtox) whereas for the ecological LoE the bait lamina test, soil basal respiration, and vegetation cover were used to derive risk values. Results and discussionThe chemical LoE showed high risk in those points inside the area where metal loadings exceeded in much the existing soil screening values. Ecotoxicological tools showed a variable response, with tests on soil organisms inducing a higher risk (again at sites inside the smelter and with sandy soils) than tests on eluates. The three parameters composing the ecological LoE revealed a concordant response, despite the lower sensitivity of the vegetation cover. A high risk on this LoE was also observed on those sampling points where a high chemical risk was calculated. Conclusions Integrated risk was low outside the smelter area. Inside, a high spatial heterogeneity of risk levels was observed, related to the non homogeneous deposition of smelting residues. Very high risk levels, associated with sandy soils and residue deposits, suggest the need to proceed with remediation actions. However, the uncertainties associated with the contradictory information given by certain LoEs for certain sampling points show the need to confirm potential risks in a tier 2 analysis.

Influence of soil properties on the performance ofFolsomia candida: Implications for its use in soil ecotoxicology testing

“…By maintaining soil invertebrate biodiversity, this endpoint reflects the quality of soil as a habitat. Therefore, it can be used as indicator in risk assessment studies [8,53,54].…”

Biological activity in Cerrado soils: evaluation of vegetation, fire and seasonality effects using the “bait-lamina test”

“…The test can be performed under different conditions (Kratz 1998). Some studies have used this method in risk assessment of contaminated areas and for testing the effects of contaminants (Helling et al 1998;Larink and Sommer 2002;Filzek et al 2004;Niemeyer et al 2010). Hamel et al (2007) and Roembke et al (2006) provided valuable discussions about the effects of vegetation and land use on soil feeding activity in temperate and tropical regions.…”

Soil ecotoxicology in Latin America: Current research and perspectives

“…Intensive mining and processing of ores have occurred historically at several locations in Latin America and resulted in severe contamination of soil, water, and sediment . In some cases, no actions were taken when government limits were exceeded by orders of magnitude.…”

“…This includes cooperation with Brazilian Agricultural Research Corporation (EMBRAPA) Agrobiologia and EMBRAPA Florestas, the São Paulo Environmental Agency, the Minas Gerais Environmental Agency, and several Brazilian universities. Among the major outcomes are important studies on a metal‐contaminated site in Bahia (Brazil) , effects of waste disposal in soils in Rio de Janeiro (Brazil) , the use of organic residues as soil amendments , and effects of pesticides ; all of these have contributed to improvements in Brazilian protective regulations.…”