The effectiveness of highly siliceous rocks in the production of environmentally safe crop production

The article presents the results of studying the influence of copper-contaminated soil (typical medium-loamy chernozem) on the ecological safety of grain and the yield of spring wheat when using high-silicate rock - diatomite as a detoxifier. It was found that when diatomite was introduced into soil contaminated with up to 4 MPC Cu at a dose of 5 t/ha, it completely blocked the negative impact of copper on the formation of spring wheat yield. Contamination of the soil with copper up to 10 MPC Cu was accompanied by its accumulation in the grain above the control by 8-35%. The introduction of diatomite into the soil helped to reduce its accumulation in products by 17-50%. Keywords: SOIL CONTAMINATION WITH COPPER, DIATOMITE, ENVIRONMENTALLY SAFE PRODUCTS

Potential Use of Copper-Contaminated Soils for Hemp (Cannabis sativa L.) Cultivation

To mitigate climate change, reducing greenhouse gas emissions can be achieved by decreasing the use of fossil fuels and increasing that of alternative sources, such as energy crops. However, one of the most important problems in the use of biomass as a fuel is that of changing soil use and consumption, leading to competition with food crops. We addressed the topic by evaluating the possibility to exploit contaminated areas for energy crops cultivation. Indeed, soil contamination makes land inappropriate for cultivation, with damaging consequences for ecosystems, as well as posing serious health hazards to living beings. Specifically, this work aimed to evaluate the ability of hemp (Cannabis sativa L.) plants to grow on a copper (Cu)-contaminated medium. In addition, the effectiveness of an environment-friendly treatment with sulfate in improving plant ability to cope with Cu-induced oxidative stress was also explored. Results showed that plants were able to grow at high Cu concentrations. Therefore, hemp could represent an interesting energy crop in Cu-contaminated soils. Although the response of Cu-treated plants was evidenced by the increase in thiol content, following modulation of sulfur metabolism, it remains to be clarified whether the use of exogenous sulfate could be an agronomic practice to improve crop performance under these edaphic conditions.

Development of mycorrhizal soybean grown in copper-contaminated soil

High concentrations of copper in the soil are toxic to the development of plants and microorganisms. The aim of this study was to select arbuscular mycorrhizal fungi efficient for the development and yield of soybeangrown in copper-contaminated soil. The experiment was laid out in a completely randomized design with a 7 × 4 factorial arrangement corresponding to seven rates of copper (0, 80, 160, 240, 320, 400, and 480 mg kg-1 of soil) and four inocula (uninoculated control and three mycorrhizal fungi, namely, Acaulospora colombiana, Dentiscutata heterogama and Rhizophagus clarus), in seven replicates. Shoot height; collar diameter; number of grains per plant; shoot and root-system dry mass; leaf area; specific root surface; copper content and accumulation in the shoots, roots, and grain; chlorophyll parameters; and mycorrhizal colonization percentage were evaluated. Inoculation with the arbuscular mycorrhizal fungi Acaulospora colombiana, Dentiscutata heterogama and Rhizophagus clarus increases the phenological and physiological parameters of soybean and its yield when grown in soil contaminated with up to 480 mg kg-1 of copper applied to the soil. The Rhizophagus clarus isolate provides greater development and yield in soybean grown in soil contaminated with up to 480 mg kg-1 of copper applied to the soil, as compared with the other isolates.

Study on Mechanical and Microscopic Properties of Nickel–Copper-Contaminated Soil Solidified by Cement, Fly Ash and Desulfurization Gypsum Under Carbonization Condition

The engineering characteristics of remediated soil are easily affected by CO2 erosion in nature. However, there are limited investigations on the mechanical and microscopic properties of heavy metal-contaminated soil. This study introduces effect of accelerated carbonization on the mechanical and microscopic properties of nickel–copper-contaminated soil, and the soil has been treated with a novel curing agent, formed by mixing cement, fly ash and desulfurization gypsum (CFG). The objective of the study is to ascertain CO2 erosion resistance of nickel–copper-contaminated soil solidified by CFG. Using unconfined compressive strength (UCS) tests, carbonization depth, X-ray diffraction, and scanning electron microscopy, the sample’s characteristics are investigated under different carbonization times and heavy metal ion concentrations. The results demonstrate that the UCS of samples of Ni0Cu0, Ni0.02, and Ni0.4 decrease with the increasing carbonization time, while that of Ni1, Cu1, and Ni1Cu1 increase initially and then decrease; in addition, when the concentration of heavy metals is lower, the effect of carbonization on UCS of samples is more significant. Moreover, the carbonization depth of samples increases with the increasing carbonization time, and the prediction model is given. Furthermore, the microscopic analysis demonstrates that calcium carbonate is the main carbonization product. The decomposition of hydrated calcium silicate gel leads to poor integrity of the structure and more pores produced in samples, which is the main reason for the decrease of the UCS in the process of carbonization. The outcomes of this investigation provide a reference for the durability in practical engineering of heavy metal-contaminated soil solidified by CFG.

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

Heavy metal and metalloid-contaminated soil is a serious barrier to colonization for many plant species. The problem of the elimination of toxic waste accumulated in technogenous soils in many highly transformed regions is extremely important. Hence, another attempt was made to analyze the effect of the addition of sorbents (BCH—biochar, B—bentonite, ChM—chicken manure, OS—organo-zeolitic substrate) to contaminated copper soil on the germination and early growth of Eurasian common grass species (Agrostis capillaris, A. stolonifera, Festuca rubra and Poa pratensis), which could potentially be used in recultivation. This experiment was based on the laboratory sandwich method. Standard germination indexes, morphometry and biomass analysis were used. The percentage of germinating seeds was lower in each of the soil variants and sorbents used compared to the control. Dry mass was positively stimulated by all sorbents. The response to the addition of sorbents, expressed as the electrolyte leakage of seedlings, was different depending on the species and type of sorbent. Among all sorbents, the most positive effects on germination and growth were observed in the case of OS. Overall, the response to the addition of sorbents was different in the studied species, depending on their stage of development.