Evaluation of the phytotoxicity of coal ash on lettuce (Lactuca sativa L.) germination, growth and metal uptake
| Autor: | Munyaradzi Mtisi, Willis Gwenzi |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Health
Toxicology and Mutagenesis 0211 other engineering and technologies Biological Availability Lactuca Germination 02 engineering and technology 010501 environmental sciences complex mixtures 01 natural sciences Coal Ash Soil Hormesis Metals Heavy Radicle Soil Pollutants Coal Biomass 0105 earth and related environmental sciences 021110 strategic defence & security studies biology Sensitive-plant business.industry Chemistry technology industry and agriculture Public Health Environmental and Occupational Health Electric Conductivity General Medicine respiratory system Hydrogen-Ion Concentration Lettuce biology.organism_classification Pollution Fly ash Environmental chemistry Soil water Phytotoxicity Environmental Pollutants business |
| Zdroj: | Ecotoxicology and environmental safety. 170 |
| ISSN: | 1090-2414 |
| Popis: | Land application of coal ash is considered an environmentally friendly option to improve soil quality, but limited information exists on metal bioavailability and phytotoxicity of coal ash to sensitive plant species such as lettuce ( Lactuca sativa L.). Germination and pot bioassay experiments were conducted at six coal application rates (0% (control), 5%, 15%, 25%, 50% and 75% v/v) to investigate the hypothesis that, coal ash will have a hormetic effect on germination, growth, metal uptake and biomass yield of lettuce, characterized by stimulatory and phytotoxicity effects at low and high application rates, respectively. Total concentrations (mg/kg) of metals in coal ash spanned several orders of magnitude, and decreased in the order: Fe (5150.5), Mn (326.0), Zn (102.6), Cu (94.7), Ni (74.7) and Pb (11.6). Bioavailable concentrations of metals were very low (0.0–14.1 mg/kg), accounting for less than 2% of the total concentrations. Coal ash had no significant effect on germination indices, but had hormetic effects on radicle elongation, evidenced by stimulatory and phytotoxicity effects at low (5–25%) and high (50–75%) application rates, respectively. Coal ash application at 50% and 75% significantly ( p p p 2 = 0.80) were observed between edible and total biomass yields and EC, suggesting that increased salinity at high coal ash application rates could account for reduced growth and biomass. Partial elemental balances showed that plant uptake of metals was very low, accounting for just less than 2% of the bioavailable concentrations, while the bulk of the metals (98–99%) remained in the soil. In conclusion, the current findings show that coal ash may have hormetic and phytotoxic effects on sensitive plant species, an observation contrary to the bulk of earlier literature documenting beneficial effects of coal ash application to soils. Long-term field studies are required to confirm the current findings based on laboratory and pot bioassay experiments. |
| Databáze: | OpenAIRE |
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