Abstract
This study was conducted in Tyumen (Russian Federation) to establish the effects of heavy metals’ (Cu, Zn, Fe, Mn, Pb, and Cd) accumulation in soil and coltsfoot, as well as plants’ biochemical responses to such an accumulation. The mobile and acid-soluble heavy metal fractions in soils, and the heavy metal contents in plants, were determined by atomic absorption spectrophotometry. The Cu, Zn, Fe, Mn, and Pb concentrations in soils exceeded background values. Pb content at the battery manufacturing plant was above the maximum permitted concentration. The percentages of the mobile heavy metal fractions decreased in the following order: Mn > Zn > Cu > Fe. The greatest heavy metal accumulation in soils and plants was found at the battery manufacturing and metallurgical plants examined in our study. Heavy metals’ accumulation in the aboveground part of Tussilago farfara decreased in the following order: Fe > Zn > Cu > Mn > Pb > Cd. The accumulation of heavy metals stimulated the synthesis of photosynthetic pigments by 6–30%. Heavy metals provoked oxidative stress in cells, increasing the concentration of lipid peroxidation in products by up to 80%. Plant phenolics and flavonoids in the urban area of our study decreased compared to those in the control by 1.05, reaching up to 6.5 times. The change in coltsfoot catalase activity both increased and declined. Biochemical responses and heavy metal accumulation in coltsfoot from urban areas limit its use for medicinal purposes.
Highlights
The industrial development and intensification of agriculture has led to an increase in heavy metal concentrations in the environment
Metal accumulation stimulated photosynthetic pigment synthesis in coltsfoot, while the metal content correlated with pigment concentrations
Heavy metals provoked oxidative stress in plants, which is registered by Fe and Mn correlations in plants with Schiff bases, as well as increments in lipid peroxidation products at the oil refinery and metallurgical plants
Summary
The industrial development and intensification of agriculture has led to an increase in heavy metal concentrations in the environment. Due to their inability to biodegrade, their high toxicity, and an ability to affect food chain migration, heavy metals are only able to accumulate in ecosystems in increasing amounts, creating an ecological threat [1,2]. Independent of type and source of emission, heavy metals appear at the soil’s surface, which leads to their accumulation in the organogenic horizon and their absorbance by plant roots [6]. Metal accumulation in soil negatively affects the latter’s fertility, plant growth, and development. Approximately 11% of soils in the Russian Federation have a high level of heavy metal contamination [7]
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