Ecotoxicological effects of chromium (VI) on seedling growth, soil nitrification and earthworm behavior

Issue Date

10-2020

Abstract

Soil Cr(VI) contamination is a long existing problem due to large quantities of wastes from various industrial sources being released into the environment. An array of ecotoxicological tests including corn (Zea mays L.) and wheat (Tricitum aestivum L.) emergence and growth, soil nitrification and earthworm (Eisenia fetida) avoidance behavior were used in this study to evaluate the potential effects of Cr(VI) on soil biota. Three South Australian soils specifically Pinnaroo (sandy loam, pH 7.40), Kalangadoo (sandy, pH 7.38) and Mount Compass (sandy, pH 5.94) were used for the plant, soil nitrification and earthworm behavior tests, accordingly. These soils, possessing high sand content, low CEC and low OM, were used to simulate a condition for low Cr(VI) sorption and increase Cr(VI) bioavailability allowing toxic effects to be more apparent for research purposes. Soil samples were spiked with different Cr(VI) concentrations (1-100 mg kg-1 for plant tests and 1-500 mg kg-1 for nitrification and earthworm tests). In the plant tests (OECD 208), the plant height of corn and wheat were significantly decreased even at low Cr(VI) concentrations of 10 and 20 mg kg-1, respectively. Furthermore, corn and wheat aboveground biomass were significantly decreased at 10 mg Cr(VI) kg-1. Nitrate levels significantly decreased due to increased Cr(VI) concentrations in the soil nitrification test (OECD 216). The avoidance behavior was observed starting at 5 mg Cr(VI) kg-1 in the earthworm avoidance assay (ISO 17512-1). The obtained EC50 values for Cr(VI) on soil nitrification and earthworm avoidance were 65.2 mg kg-1 and 22.4 mg kg-1, respectively. Results showed significant negative effects of Cr(VI) on soil biota as evident on the decreased corn and wheat plant growth, decreased microbially-mediated soil nitrification and increased earthworm avoidance in the contaminated soils. Results of this ecotoxicological study can be used as basis for remediation activities performed on Cr(VI) polluted soil.

Source or Periodical Title

Journal of the International Society for Southeast Asian Agricultural Sciences

ISSN

0859-3132

Volume

26

Issue

2

Page

122-132

Document Type

Article

Physical Description

illustrations; graphs; tables; references

Language

English

Subject

Earthworm avoidance, Ecotoxicity, Nitrification, Seedling growth

Digital Copy

yes

En – AGROVOC descriptors

EARTHWORM AVOIDANCE; ECOTOXICITY; NITRIFICATION; SEEDLING GROWTH

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