Effects of Natural Sorbents on the Germination and Early Growth of Grasses on Soils Contaminated by Potentially Toxic Elements

Abstract

The reclamation of abandoned mining heaps rich in potentially toxic elements (PTEs) is critical for the environment. We carried out a laboratory experiment studying the effects of the addition of four natural sorbents (biochar, bentonite, chicken manure and organo-zeolitic substrate) to soils contaminated with PTEs, predominantly Cu, As and Sb, on the germination and growth of the autochthonous grasses Agrostis capillaris, A. stolonifera, Festuca rubra and Poa pratensis. The experiment used Petri dish tests with water extracts of contaminated soil and soil neutralised with the four sorbents. Standard indexes of the germination process were used (germination percentage, time required for 50% germination index, speed of emergence), and different values were found depending on the plant species and sorbent used. However, the percentage of seeds germinating was lower for each sorbent compared to the control (distilled water). The fresh mass values were positively stimulated by all sorbents. Electrolyte leakage was the highest in seedlings watered with an extract of untreated soil from the heap compared to extracts from treated soils and the control. This can be interpreted as eliminating the harmful effects of increased potentially toxic element (PTE) contents by sorbents, which can be useful in remediation processes.

Effect of Sorbent Additives to Copper-Contaminated Soils on Seed Germination and Early Growth of Grass Seedlings

“…The aim of this experiment was to investigate the effect of the additives of five selected sorbents on the germination and growth of Eurasian common grasses, on a substrate containing soil contaminated with copper and other potentially toxic ingredients. These studies are a continuation of the experiment described in the study by Turisová et al [ 52 ].…”

“…Such reactions of seedlings most likely resulted from the too short contact time between the seeds and the soils, which made it difficult to record a clear response to the applied remediation substances, contrary to the reaction of the same seeds treated with aqueous extracts from soil contaminated with copper and its modification with sorbents. Perhaps direct contact with chemical compounds extracted from the soil allowed us to verify to a greater extent which of the sorbents positively influences the germination and early growth of grass seeds [ 52 ].…”

“…The average copper content in the soil samples was 1099 mg·kg −1 , which is several times higher than the EU limit value according to Council Directive 86/278/EEC (50 to 140 mg·kg −1 ) [ 71 ]. The characteristics of this area have been described in detail in the paper of Turisová et al [ 52 ]. In these areas, copper and silver ore mining was carried out over several centuries.…”

“…As in the previous experiment [ 52 ], in this study, four common grass species typical for Eurasian areas were selected: Agrostis capillaris L., A. stolonifera L., Festuca rubra L., Poa pratensis L. The grass seeds were bought from DLF SeeDs (Hladké Životice, Czech Republic). A. capillaris (common bent, browntop) is a perennial grass with very thin blades (stalks); its blades rise obliquely and are rough under the panicle.…”

Ecophysiological Parameters of Medicinal Plant Filipendula vulgaris in Diverse Habitat Conditions

“…The better condition of the dropwort population from xerothermic grassland than wet meadow was also concluded in the previous research of Kostrakiewicz-Gierałt and Stachurska-Swakoń [ 27 ], where the population from xerothermic grasslands was more numerous, with better parameters according to seedling recruitment and specimen size. The lower content of heavy metals is important already during the germination of plants, and the phytotoxicity of these elements increases with their concentration in the soil [ 56 , 57 , 58 ]. Germination is among the first steps in the contact of seeds with a stress factor, which makes them a specific indicator of sensitivity and a measure of tolerance to chemical and physical conditions of the rhizosphere [ 59 , 60 , 61 , 62 ].…”