Gypsum soil amendment in metal-polluted soils—an added environmental hazard

Scientists around the world have long been searching for effective strategies to reduce the bioavailability of metals in contaminated soils. In case of metal-spiked soils, some studies have proposed gypsum as a soil amendment to alleviate metal phytotoxicity. However, for real field-collected soils, evidence on the efficacy of gypsum as a metal phytotoxicity amendment is limited. Therefore, the present study was designed to examine the effect of gypsum on plant growth in soils polluted by a copper smelter. We grew perennial ryegrass on untreated and gypsum-treated soils (at a dose of 3% by weight) under laboratory conditions. We found that gypsum had no effect on alleviating metal phytotoxicity in our soils. We also demonstrated – for the first time – that gypsum increased the concentrations of soluble metals in the soil, enhancing metal uptake by plants. The calcium ions from gypsum displace metals in the soil exchangeable complex; however, the metals do not get immobilized in soils because gypsum is a neutral salt. While our results contrast with the Terrestrial Biotic Ligand Model, that Model has never been tested on real industrially polluted soils but only on metal-spiked soils. Our main conclusion is that gypsum is ineffective in alleviating metal phytotoxicity in real industrially polluted soils and, moreover, its use is inappropriate as a soil remediation method, because it increases the environmental hazard rather than reducing it. Our study is the very first attempt to recognize that gypsum is a hazardous material when used to ameliorate soils polluted by metals. © 2021 Elsevier Lt

CHALLENGES IN REDUCING PHYTOTOXICITY OF METALS IN SOILS AFFECTED BY NON-FERROUS SMELTER OPERATIONS

Lime is one of the effective agents for reducing the phytoavailability of metals in contaminated acidic soils. However, previous studies have shown that lime alone cannot reduce metal phytotoxicity to the desired extent in such soils. The goal of this study was to evaluate the effect of different amendment combinations (lime with and without Feand/or Mn-based amendments) on plant growth. A sample of Histosol (0-5 cm) was collected around a Cu/Ni smelter near Monchegorsk, Murmansk region, exhibiting total Cu and Ni concentrations in the soil of 6418 and 2293 mg kg-1, respectively. Likewise, a sample of forest litter (0-15 cm) was collected around a Cu smelter near Revda, Sverdlovsk region, exhibiting total Cu concentration in the soil of 5704 mg kg-1. Fe-Mn oxides were sourced from ferromanganese nodules in the Gulf of Finland, and iron powder was used as a precursor for iron oxides. Perennial ryegrass was grown in pots for 21 days under controlled laboratory conditions. Two dolomite doses were tested: 5% w/w (giving a soil pH of 6.5) and 20% w/w (giving a soil pH of 7.4). Over-liming stunted plant growth; therefore, the dolomite dose was set at 5% in the further experiments of the study. Importantly, the addition of 0.5% and 1% of Fe-Mn-oxides or iron powder did not improve the efficacy of the lime amendment in promoting plant growth in the soils. Therefore, the issue of reducing plant exposure to metals remained unresolved in the soils under study. © 2022, Russian Geographical Society. All rights reserved

Root Elongation Method for the Quality Assessment of Metal-Polluted Soils: Whole Soil or Soil-Water Extract?

Root elongation method may be implemented using two internationally accepted protocols: exposing plants to either soil-water extract or whole soil. But which of the two protocols is more suitable for root elongation analysis undertaken for the quality assessment of metal-polluted soils? Soils were sampled at various distances from the site of the Middle Urals Copper Smelter located in Russia. White mustard was used as a bioindicator. We observed considerable differences in root elongation under the two protocols. In plants grown in whole soil, root length inversely correlated with pollution index, but in soil-water extract, metal concentrations had no effect on root length. Nutrient and metal concentrations in the soil-water extract were not buffered, due to the absence of the solid soil phase. It is for this reason that in highly polluted soils, root growth was greater in soil-water extracts rather than in whole soils, whereas in background soils (in the absence of toxicity), root growth was greater in whole soils compared with soil-water extracts. The quantity, intensity, and capacity factors are a plausible explanation for the differences in root length between the two protocols. The soil-water extract does not represent actual soil with respect to the desorption-dissolution reactions that take place between the soil solid phase and the soil solution. For this reason, whole soil protocol should be used for measuring root elongation given that only under this protocol, direct contact between metal-polluted soil and test organisms correctly replicates the risks inherent in the actual soil habitat. © 2020, Sociedad Chilena de la Ciencia del Suelo

Право и экономика: современные интеграционные процессы

Монография посвящена вопросам интеграции права и экономики. Особый акцент сделан на государственном регулировании предпринимательской деятельности, развитии высокотехнологичной экономики, обеспечении финансово-экономической безопасности, правовом регулировании отдельных видов предпринимательской деятельности, а также рассмотрены новые механизмы обязательственного и договорного права. Монография является результатом научного сотрудничества ученых образовательных организаций, практических работников юридических лиц, а также молодых специалистов предпринимательской сферы. Работа выполнена в рамках исследования научной школы Финансового университета при Правительстве Российской Федерации «Государственное регулирование предпринимательской деятельности». Для юристов, экономистов, представителей органов исполнительной и законодательной власти, а также для широкого круга читателей, интересующихся рассматриваемой тематикой

Право и экономика: современные интеграционные процессы

Монография посвящена вопросам интеграции права и экономики. Особый акцент сделан на государственном регулировании предпринимательской деятельности, развитии высокотехнологичной экономики, обеспечении финансово-экономической безопасности, правовом регулировании отдельных видов предпринимательской деятельности, а также рассмотрены новые механизмы обязательственного и договорного права. Монография является результатом научного сотрудничества ученых образовательных организаций, практических работников юридических лиц, а также молодых специалистов предпринимательской сферы. Работа выполнена в рамках исследования научной школы Финансового университета при Правительстве Российской Федерации «Государственное регулирование предпринимательской деятельности». Для юристов, экономистов, представителей органов исполнительной и законодательной власти, а также для широкого круга читателей, интересующихся рассматриваемой тематикой