Vermiculite-Lizardite Industrial Wastes Promote Plant Growth in a Peat Soil Affected by a Cu/Ni Smelter: a Case Study at the Kola Peninsula, Russia

Abstract

Some industrial barren areas are extreme habitats created by the deposition of airborne pollutants from non-ferrous smelters. One of such barrens exists in the vicinities of the Cu/Ni smelter, located at the Kola Peninsula, Murmansk region, Russia. This study aimed at evaluating in laboratory conditions the efficiency of various vermiculite-lizardite wastes (industrial wastes of local origin) as soil amendments for plant growth promotion. Peat topsoil (0-20 cm) was collected in the vicinity of the Cu/Ni smelter. Total soil concentrations were 1612, 1481, and 63 mg kg −1 for Ni, Cu, and Co, respectively, and soil pH was 4.3. Soils were amended with lime waste and different types of vermiculite-lizardite wastes (coarse, fine, and thermo-activated at 700°C), leaving one soil untreated. Weekly wetting-drying cycles, performed during 1 month, allowed amendments to react in the soil. All soils were cultivated with Lolium perenne L. for 21 days under controlled conditions. The plant growth was not influenced by high soil Cu concentration, while Ni and Co caused phytotoxicity. A mix of 10% (w/w) of different vermiculite-lizardite wastes with 10% (w/w) of lime improved the plant growth. Thermo-activated waste showed the best results for promoting plant growth and reducing foliar Ni concentrations from 1022 to 88-117 mg kg −1. However, the plants presented Ni phytotoxicity even in the amended soils and this requires further studies to find a way to reduce it.

The challenge of reducing metal phytotoxicity insoils affected by historical nickel-copper smelting operations in the Kola Peninsula, Russia

“…Consistent with this finding, our recent experiment under laboratory conditions were similar to those in the present study (Tarasova et al, 2020), demonstrating a linear relationship between L. perenne shoot length and growth time in uncontaminated commercial peat. In contrast, Tarasova et al (2020) revealed a non-linear relationship of shoot growth with growth time in polluted Histosol extracted from the vicinity of the Ni/Cu smelter, both before and after treatment. Given that the study of Tarasova et al (2020) used substrates of peats diffe- ring only in the degree of metal pollution, we infer that plant growth was negatively impacted by metal toxicity in polluted soils even after treatment.…”

“…We noted that early shoot growth in grasses-and Lolium species in particular-had a linear relationship with growth time (Thomas et al, 1999). Consistent with this finding, our recent experiment under laboratory conditions were similar to those in the present study (Tarasova et al, 2020), demonstrating a linear relationship between L. perenne shoot length and growth time in uncontaminated commercial peat. In contrast, Tarasova et al (2020) revealed a non-linear relationship of shoot growth with growth time in polluted Histosol extracted from the vicinity of the Ni/Cu smelter, both before and after treatment.…”

“…Our previous laboratory experiment demonstrated that lime and vermiculite-lizardite mixture is indeed an effective amendment to promote plant growth (shoot length and biomass) in soils collected from the surroundings of the Ni/Cu smelter (Tarasova et al, 2020). Howe-ver, we found that even plants grown in the amended soils displayed signs of metal phytotoxicity, suggesting that experiments with additional amendment combinations were needed.…”

“…Plant bioassay was carried out following a standard protocol (ISO 11269-2, 2012), as described in detail in our previous study (Tarasova et al, 2020). Foliar elemental concentrations were established after 21 days of plant growth using the ICP-MS technique on a Perki-nElmer ELAN 9000 DRC-e mass-spectrometer following microwave digestion with a mixture of concentrated HF+HCl+HNO 3 .…”

“…Thus, the goal of this study was to determine the effect of peat addition to the lime + vermiculite-lizardite combined amendment on plant growth in the soils from the vicinity of the Ni/Cu smelter. We decided to test the selected amendments under laboratory conditions first, similar to what we did in a recent study (Tarasova et al, 2020), before considering a field-scale investigation.…”