Evaluation of environmental contamination by toxic trace elements in Kazakhstan based on reviews of available scientific data

International audienceThe environmental situation concerning pollution by (eco)toxic and persistent trace elements in Kazakhstan has been investigated by analytical reviews of scientific studies published over the past 20 years reporting concentrations of 10 toxic trace elements (TTE) observed in soil, sediments or surface water. A database of 62 articles published in Kazakh, Russian or English covered the majority of the territory of the country for soil and water samples but to a lesser extent for sediments. Reported concentrations were summarized using statistical parameters, then spatialized and finally classified in contamination classes according to local legislation. This analysis revealed some hotspots of TTE in surface waters (Cd and Pb), soil (As) and sediments (Cd and As). Hotspots of less toxic Cu, Zn and Mn were also detected. Spatialization of results allowed localization of these hotspots close to industrial sites, such as smelters or mining and metallurgic combines. Others have been shown to be close to disused mining sites or landfills with municipal waste. Methodological improvements for further studies have been suggested, such as to integrate more West Kazakhstan or remote areas in sampling campaigns, but also to describe more exhaustively the used analytical methods and to be more attentive to the speciation of the analyzed form of the element. Finally, a management strategy to strengthen a sustainable food policy has been proposed: to reduce emissions by modernization of industrial facilities and better waste management, to organize land use depending on the contamination levels and to reduce the bioavailability of the toxic elements

Influence of Osmotic, Salt, and Combined Stress on Morphophysiological Parameters of <i>Chenopodium quinoa</i> Photosynthetic Organs

Chenopodium quinoa Willd. is an annual facultative halophytic pseudocereal widely studied for its physiology and grain yield owing to its great tolerance to unfavorable growing conditions. However, the morphophysiological and anatomical characteristics of plants’ photosynthetic organs under various and combined abiotic stresses during the early stages of development have not been thoroughly studied. Therefore, the current study compared the influence of osmotic, salt, and combined stress at different intensities on the morphology and anatomy of photosynthetic organs in young quinoa plants. The main findings demonstrate that salt stress at an intensity between 100 and 200 mM NaCl is not critical for the growth of young quinoa plants and that the young plants can withstand salt stress at an intensity of 300 mM NaCl. However, it can be concluded that some adaptation mechanisms of the plants were already violated at a salt stress intensity of 200 mM NaCl, while significant changes in the water balance of the plants were observed at an intensity of 300 mM NaCl, possibly caused by damage to the cell structures

Phytoremediation of Soil Contaminated by Organochlorine Pesticides and Toxic Trace Elements: Prospects and Limitations of <i>Paulownia tomentosa</i>

Paulownia tomentosa (Thunb.) Steud is a drought-resistant, low-maintenance and fast-growing energy crop that can withstand a wide range of climatic conditions, provides a high biomass yield (approximately 50 t DM ha−1 yr−1), and develops successfully in contaminated sites. In Kazakhstan, there are many historically contaminated sites polluted by a mixture of xenobiotics of organic and inorganic origin that need to be revitalised. Pilot-scale research evaluated the potential of P. tomentosa for the phytoremediation of soils historically contaminated with organochlorine pesticides (OCPs) and toxic trace elements (TTEs) to minimise their impact on the environment. Targeted soils from the obsolete pesticide stockpiles located in three villages of Talgar district, Almaty region, Kazakhstan, i.e., Amangeldy (soil A), Beskainar (soil B), and Kyzylkairat (soil K), were subjected to research. Twenty OCPs and eight TTEs (As, Cr, Co, Ni, Cu, Zn, Cd, and Pb) were detected in the soils. The phytoremediation potential of P. tomentosa was investigated for OCPs whose concentrations in the soils were significantly different (aldrin, endosulfans, endrin aldehyde, HCB, heptachlor, hexabromobenzene, keltan, methoxychlor, and γ-HCH) and for TTEs (Cu, Zn, and Cd) whose concentrations exceeded maximum permissible concentrations. Bioconcentration (BCF) and translocation (TLF) factors were used as indicators of the phytoremediation process. It was ensured that the uptake and translocation of contaminants by P. tomentosa was highly variable and depended on their properties and concentrations in soil. Besides the ability to bioconcentrate Cr, Ni, and Cu, P. tomentosa demonstrated very encouraging results in the accumulation of endosulfans, keltan, and methoxychlor and the phytoextraction of γ-HCH (TLFs of 1.9–9.9) and HCB (BCFs of 197–571). The results of the pilot trials support the need to further investigate the potential of P. tomentosa for phytoremediation on a field scale

Miscanthus &times; giganteus Phytoremediation of Soil Contaminated with Trace Elements as Influenced by the Presence of Plant Growth-Promoting Bacteria

The phytoremediation of industrial crops is becoming popular for the revitalization of land contaminated by trace elements (TEs). This approach combines biomass production with the improvement of soil health. To implement phytoremediation and derive sufficient dry biomass, crop production must be adequately supported by agricultural practices, including the application of bioinoculants. The current study aims to test the influence of several plant growth-promoting bacteria (PGPB), isolated from TEs-contaminated soil&mdash;i.e., Stenotrophomonas maltophilia KP-13, Bacillus altitudinis KP-14, and Pseudomonas fluorescens KP-16 and their consortia on the phytoremediation of the industrial crop M. &times; giganteus cultivated in the same TEs-contaminated soil. Contrary to expectations, the effects of PGPB on the biomass harvest were low. The most significant increase was detected in leaf biomass treated with a consortium of tested PGPBs. More significant effects were detected in the uptake of individual TEs. The phytoparameters of translocation factor, comprehensive bioconcentration index and uptake index were used to characterize the behavior of the TEs; Cr; Mn; Ni; Cu; Zn; Sr; V; and Pb in the presence of isolates. Plants treated with PGPB strains accumulated minimal concentrations of Cu and Pb in their aboveground biomass, while a tendency for Zn accumulation in the leaves and stems, and Sr accumulation in the leaves was observed. The obtained results reveal the combinations of isolates that lead to the minimal uptake of TEs into the stems and the simultaneous increase in DW. This study provides more insight into the leading factors of phytoremediation supported by PGPB and can be helpful when M. &times; giganteus is grown on TEs-contaminated soils of different origins

<i>Miscanthus</i> × <i>giganteus</i> Phytoremediation of Soil Contaminated with Trace Elements as Influenced by the Presence of Plant Growth-Promoting Bacteria

The phytoremediation of industrial crops is becoming popular for the revitalization of land contaminated by trace elements (TEs). This approach combines biomass production with the improvement of soil health. To implement phytoremediation and derive sufficient dry biomass, crop production must be adequately supported by agricultural practices, including the application of bioinoculants. The current study aims to test the influence of several plant growth-promoting bacteria (PGPB), isolated from TEs-contaminated soil—i.e., Stenotrophomonas maltophilia KP-13, Bacillus altitudinis KP-14, and Pseudomonas fluorescens KP-16 and their consortia on the phytoremediation of the industrial crop M. × giganteus cultivated in the same TEs-contaminated soil. Contrary to expectations, the effects of PGPB on the biomass harvest were low. The most significant increase was detected in leaf biomass treated with a consortium of tested PGPBs. More significant effects were detected in the uptake of individual TEs. The phytoparameters of translocation factor, comprehensive bioconcentration index and uptake index were used to characterize the behavior of the TEs; Cr; Mn; Ni; Cu; Zn; Sr; V; and Pb in the presence of isolates. Plants treated with PGPB strains accumulated minimal concentrations of Cu and Pb in their aboveground biomass, while a tendency for Zn accumulation in the leaves and stems, and Sr accumulation in the leaves was observed. The obtained results reveal the combinations of isolates that lead to the minimal uptake of TEs into the stems and the simultaneous increase in DW. This study provides more insight into the leading factors of phytoremediation supported by PGPB and can be helpful when M. × giganteus is grown on TEs-contaminated soils of different origins

The Role of Plant Growth Regulators in <i>Miscanthus × giganteus</i> Growth on Trace Elements-Contaminated Soils

Soil contamination with trace elements (TEs) is a pressing problem limiting the cultivation of agricultural crops; however, the non-food energy crop Miscanthus × giganteus (M×g) can be grown on such soil. The effect of a new plant growth regulator (PGR), Kamethur, and conventional Charkor was studied when M×g was cultivated in TE-contaminated soils from Všebořice and Chomutov, in the Northern Czech Republic. Kamethur was beneficial for achieving a higher leaves and stem biomass (by 57.1 and 126%, respectively) in the more contaminated Všebořice soil, while Charkor increased only the leaves biomass (49.5%). Analysis of the comprehensive bio-concentration index showed that Charkor decreased stem accumulation of elements essential for plant development (EEs), as well as the potentially toxic (PTEs) elements, by 33.3 and 11.4%, respectively. Kamethur decreased stem accumulation of EEs by 11.4% and increased the accumulation of PTEs by 23.3%. Statistical evaluation of the current results and literature data illustrated the ability of Charkor to reduce the uptake of PTEs, which is critical for converting clean biomass to bioproducts. Further research should confirm the influence of PGRs on the bioparameters and phytoremediation processes of M×g at the field plantation level

The Short-Term Effects of Amendments on Nematode Communities and Diversity Patterns under the Cultivation of <i>Miscanthus × giganteus</i> on Marginal Land

The short-term effects of soil amendments on the structure, diversity and function of a nematode community of Miscanthus × giganteus was investigated. Crop was cultivated on marginal, nutrient-poor land amended with biochar in single and double doses (BD1 and BD2), biogas digestate (D), sewage sludge (SS), and hemicellulose waste (HW). Sampling was done after planting, in the middle and end of vegetation; morphology-based approach was used. 28 nematode taxa were identified, including 5 bacterivores genera, 4 fungivores genera, 5 herbivores genera (11 species), 2 omnivores genera, 5 predators genera. The general linear models, correspondence analysis and clustering were applied for evaluation. The total abundance of nematode taxa Filenchus, Dorylaimus, Cephalobus, Panagrolaimus, Aphelenchus, and Ditylenchus was depended on the sampling time and amendments. The incorporation of amendments affected nematode food web and resulted in suppression of plant-parasitic nematodes (PPNs). It was revealed that community structure was more mature for SS, less stable for D and had inconclusive effects for BD1, BD2, and HW. Using amendments ensured pest control benefits which is important given concern that PPNs can inflict crop damage during increased cultivation of M × g. Further research is needed to examine amendments which can minimise PPNs without reducing populations of nitrogen-fixing bacterivores and fungivores

Evaluation of the impact of varied biochars produced from M. × giganteus waste and application rate on the soil properties and physiological parameters of Spinacia oleracea L.

The use of M. x giganteus in phytoremediation requires treatment of the contaminated biomass, which can be done by pyrolysis to produce biochar. Due to its potentially detrimental properties, the application of biochar in soil remediation must first be evaluated on a test plant to infer how the growth process was affected by the impact on soil parameters. The main goal of the current research was to investigate the effects of waste-derived Miscanthus biochars (from contaminated rhizomes (B1) and aboveground biomass (B2)) on soil properties and evaluate the impact of biochar doses and properties on Spinacia oleracea L. growth. It was revealed that incorporation of B1 at a dose of 5% and B2 at doses of 1, 3, and 5% increased soil organic carbon, pH, K (at 3 and 5%), and P2O5 (at 5% B2). Cultivation of S. oleracea reduced organic carbon, soil pH as a function of biochar dosage, and K, P2O5, NH4, and NO3 content in all treatments tested. The highest biomass yield was recorded at 3% B2. The photosynthetic parameters indicated that the doses of 3 and 5% B2 led to dissociation of light-harvesting complexes. Increasing the biochar dose did not necessarily increase yield or improve photosynthetic parameters. S. oleracea adapted to the initial stress by incorporating biochar and managed to establish a balance between nutrients, water supply, and light. It is recommended that the effects of biochar on the development of the target crop be evaluated through preliminary trials before biochar is applied at field scale.Web of Science28art. no. 10289