Beata Smolińska

Green waste compost as an amendment during induced phytoextraction of mercury-contaminated soil

Phytoextraction of mercury-contaminated soils is a new strategy that consists of using the higher plants to make the soil contaminant nontoxic. The main problem that occurs during the process is the low solubility and bioavailability of mercury in soil. Therefore, some soil amendments can be used to increase the efficiency of the Hg phytoextraction process. The aim of the investigation was to use the commercial compost from municipal green wastes to increase the efficiency of phytoextraction of mercury-contaminated soil by Lepidium sativum L. plants and determine the leaching of Hg after compost amendment. The result of the study showed that Hg can be accumulated by L. sativum L. The application of compost increased both the accumulation by whole plant and translocation of Hg to shoots. Compost did not affect the plant biomass and its biometric parameters. Application of compost to the soil decreased the leaching of mercury in both acidic and neutral solutions regardless of growing medium composition and time of analysis. Due to Hg accumulation and translocation as well as its potential leaching in acidic and neutral solution, compost can be recommended as a soil amendment during the phytoextraction of mercury-contaminated soil.

Antioxidative response of Lepidium sativum L. during assisted phytoremediation of Hg contaminated soil

In this study, Lepidium sativum L. was used in repeated phytoextraction processes to remove Hg from contaminated soil, assisted by combined use of compost and iodide (KI). L. sativum L. is sensitive to changes in environmental conditions and has been used in environmental tests. Its short vegetation period and ability to accumulate heavy metals make it suitable for use in repeated phytoextraction. The antioxidant enzymatic system of the plant (catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and glutathione S-transferase (GST)) was analysed, to understand the effects of increasing Hg accumulation and translocation. Phytoextraction was repeated six times to decrease Hg contamination in soil, and the efficiency of each step was assessed. The results indicate that L. sativum L. is able to take up and accumulate Hg from contaminated soil. A corresponding increase in enzymatic antioxidants shows that the plant defence system is activated in response to Hg stress. Using compost and KI increases total Hg accumulation and translocation to the above-ground parts of L. sativum L. Repeating the process decreases Hg contamination in pot experiments in all variants of the process. The combined use of compost and KI during repeated phytoextraction increases the efficiency of Hg removal from contaminated soil.

Influence of combined use of iodide and compost on Hg accumulation by Lepidium sativum L.

This study focuses on the influence of adding iodide (KI) and compost in different soil/compost ratios on the efficiency of Hg phytoextraction by Lepidium sativum L. Plant growth and non-enzymatic antioxidants are studied to understand metabolic plant adaptations to Hg stress during soil reclamation and their relations to Hg accumulation. Due to the use of relatively high chelant dosages in current plant-based soil remediation techniques and associated environmental risks, it is necessary to explore alternative approaches to the phytoextraction of Hg from contaminated soils. The results show a coordinated increase in non-enzymatic antioxidants in plants cultivated in growing media containing polluted soil, compost and KI. This indicates that the non-enzymatic antioxidative defence system of L. sativum L. is involved in its strategy to survive conditions of mercury-induced stress. Adding compost and iodide to Hg polluted soil also increases the total accumulation of Hg by L. sativum L. and the translocation of pollutants to aerial plant tissues. Simultaneous application of compost and KI promoted the Hg accumulation by L. sativum L. in a pot experiment.

Protein changes in Lepidium sativum L. exposed to Hg during soil phytoremediation

ABSTRACT Some investigations have been carried out in this study to find the best technique of soil reclamation in mercurypolluted soil. In this study, we examined Lepidium sativum L. as a plant useful for Hg phytoextraction. The simultaneous application of compost and thiosulfate was explored as a possible method of enhancing the process of phytoextraction. The results of the investigations of plant protein changes during assisted Hg phytoextraction were also provided. The results of the study show that combined use of compost and thiosulfate significantly increased both the total Hg accumulation and its translocation to aerial plant tissues. Plant protein analysis showed that L. sativum L. has the ability to respond to environmental stress condition by the activation of additional proteins. The additional proteins, like homocysteine methyltransferase, ribulose bisphosphate carboxylases (long and short chains), 14-3-3-like protein, and biosynthesis-related 40S ribosomal protein S15, were activated in plant shoots only in experiments carried out in Hg-polluted soil. There were no protein changes observed in plants exposed to compost and thiosulfate. It suggests that the combined use of compost and thiosulfate decreased Hg toxicity.

Photosynthetic pigments and peroxidase activity of Lepidium sativum L. during assisted Hg phytoextraction

The study was conducted to evaluate metabolic answer of Lepidium sativum L. on Hg, compost, and citric acid during assisted phytoextraction. The chlorophyll a and b contents, total carotenoids, and activity of peroxidase were determined in plants exposed to Hg and soil amendments. Hg accumulation in plant shoots was also investigated. The pot experiments were provided in soil artificially contaminated by Hg and/or supplemented with compost and citric acid. Hg concentration in plant shoots and soil substrates was determined by cold vapor atomic absorption spectroscopy (CV-AAS) method after acid mineralization. The plant photosynthetic pigments and peroxidase activity were measured by standard spectrophotometric methods. The study shows that L. sativum L. accumulated Hg in its aerial tissues. An increase in Hg accumulation was noticed when soil was supplemented with compost and citric acid. Increasing Hg concentration in plant shoots was correlated with enhanced activation of peroxidase activity and changes in total carotenoid concentration. Combined use of compost and citric acid also decreased the chlorophyll a and b contents in plant leaves. Presented study reveals that L. sativum L. is capable of tolerating Hg and its use during phytoextraction assisted by combined use of compost and citric acid lead to decreasing soil contamination by Hg.

Influence of Heavy Metals (Ni, Cu, and Zn) on Nitro-Oxidative Stress Responses, Proteome Regulation and Allergen Production in Basil (Ocimum basilicum L.) Plants

One of the most significant biosphere contamination problems worldwide is derived from heavy metals. Heavy metals can be highly reactive and toxic according to their oxidation levels. Their toxic effects are associated with the increased production of reactive oxygen species (ROS) and cellular damage induced in plants. The present study focuses on the effects of nickel (Ni), copper (Cu), and zinc (Zn) applied to the soil on the antioxidant response and allergen production in the aromatic plant basil (Ocimum basilicum L.) following a combined physiological, biochemical and analytical approach. The concentrations used for the three heavy metals were based on the 2002 Regulation of the Polish Ministry of the Environment on Soil Quality Standards [(i) agricultural land (group B): Ni 100 ppm, Ni 210 ppm, Cu 200 ppm, Cu 500 ppm, Zn 720 ppm and (ii) industrial land (group C): Ni 500 ppm, Cu 1000 ppm, Zn 1500 ppm, Zn 3000 ppm]. The highest physiological and cellular damage in basil plants was caused by Cu and Zn. Increasing concentrations of Cu resulted in a further increase in cellular damage and nitro-oxidative stress, correlating with an induction in activity of reactive oxygen and nitrogen species metabolism enzymes (SOD, CAT, APX, NR). Treatment with Cu led to increased concentration of the allergenic protein profilin, while increasing concentrations of Cu and Zn led to a decrease in the concentration of total proteins (likely due to proteolysis) and antioxidant capacity. Interestingly, severe Cu stress resulted in the accumulation of specific proteins related to transpiration and photosynthetic processes. On the basis of these findings, Ni stress in basil plants appears to be less damaging and with lower allergenic potential compared with Cu and Zn stress, while Cu-stressed basil plants experience most detrimental effects and display highest allergen production.

IODIDE FOR THE PHYTOEXTRACTION OF MERCURY CONTAMINATED SOIL

Garden cress (Lepidium sativum) plants were grown in soil artificially contaminated with mercury salts: HgCl2, HgSO4, Hg(NO3)2. Laboratory investigations were performed to evaluate the accumulation of Hg in roots, stems and leaves of the plant before/after iodide amendment to the soil. The result showed that Lepidium sativum accumulated mercury from soil, but overall maximum concentration of mercury was found in roots of the plants. Iodide application to the soil caused mercury mobilisation and thereby increased the bioavailability of Hg in soil, which effected in increase of Hg concentration in the plant. Effective accumulation by whole plant and by shoots was higher compared to the process, which was carried out without iodide addition. Enhancing the phytoextraction by addition of potassium iodide increases the efficiency of the process. In spite of using soil amendment (KI), over 80% of total mercury concentration in Lepidium sativum was accumulated in roots of the plant. Therefore this plant has a potential to be a good phytostabilizer. Lepidium sativum is an important medicinal plant and a vegetable consumed by people, for that reason there is a possibility of including Hg into food-chain. Toxicological risks should be consider before using this plant for cleaning soil contaminated by Hg.