Soil Toxicity Research Articles

ЭКОЛОГИЧЕСКАЯ ОЦЕНКА СОСТОЯНИЯ ПОЧВ МЕТОДАМИ БИОИНДИКАЦИИ

Biotesting of soils in various districts of Bishkek was carried out. The sections of the western, eastern and southern parts of the city, characterized by different traffic congestion, were surveyed. Test cultures of freshwater crustaceans Daphnia magna and ciliates Paramecium caudatum were used to determine soil toxicity. Cultivation water was taken for control. The experiments were carried out in triplicate. The cultures were placed in a climatostat for 120 hours. The survival rate and sensitivity of test cultures were determined. Mathematical integral calculation methods were used to determine the degree of toxicity in the soil. Survival of bioindicator organisms varies from less toxic to acutely toxic to test systems. The cleanest area is the territory of the southern part of the city, in which there is a park area. The methods of bioindication of the state of soils used in this study make it possible to obtain preliminary reliable information on the state of soil ecosystems and are one of the aspects of the Triad approach in assessing environmental pollution.

Reduction of bioavailability and phytotoxicity effect of cadmium in soil by microbial-induced carbonate precipitation using metabolites of ureolytic bacterium Ochrobactrum sp. POC9.

The application of ureolytic bacteria for bioremediation of soil contaminated with heavy metals, including cadmium (Cd), allows for the efficient immobilization of heavy metals by precipitation or coprecipitation with carbonates. Microbially-induced carbonate precipitation process may be useful also in the case of the cultivation of crop plants in various agricultural soils with trace but legally permissible Cd concentrations, which may be still uptaken by plants. This study aimed to investigate the influence of soil supplementation with metabolites containing carbonates (MCC) produced by the ureolytic bacterium Ochrobactrum sp. POC9 on the Cd mobility in the soil as well as on the Cd uptake efficiency and general condition of crop plants (Petroselinum crispum). In the frame of the conducted studies (i) carbonate productivity of the POC9 strain, (ii) the efficiency of Cd immobilization in soil supplemented with MCC, (iii) crystallization of cadmium carbonate in the soil enriched with MCC, (iv) the effect of MCC on the physico-chemical and microbiological properties of soil, and (v) the effect of changes in soil properties on the morphology, growth rate, and Cd-uptake efficiency of crop plants were investigated. The experiments were conducted in soil contaminated with a low concentration of Cd to simulate the natural environmental conditions. Soil supplementation with MCC significantly reduced the bioavailability of Cd in soil with regard to control variants by about 27-65% (depending on the volume of MCC) and reduced the Cd uptake by plants by about 86% and 74% in shoots and roots, respectively. Furthermore, due to the decrease in soil toxicity and improvement of soil nutrition with other metabolites produced during the urea degradation (MCC), some microbiological properties of soil (quantity and activity of soil microorganisms), as well as the general condition of plants, were also significantly improved. Soil supplementation with MCC enabled efficient Cd stabilization and significantly reduced its toxicity for soil microbiota and plants. Thus, MCC produced by POC9 strain may be used not only as an effective Cd immobilizer in soil but also as a microbe and plant stimulators.

Effects of burn severity on organic nitrogen and carbon chemistry in high-elevation forest soils

Fire frequency and severity have increased in recent decades in the western United States, with direct implications for the quantity and composition of soil organic matter (SOM). While the effects of wildfire on soil carbon (C) and inorganic nitrogen (N) have been well studied, little is known about its impacts on soil organic N. Since organic N is the most abundant form of soil N in conifer forests and dominant source of plant N facilitated by symbiotic mycorrhizae and mineralization, better understanding of post-fire organic N chemistry will help address a critical gap in our understanding of fire effects on SOM. Here, we characterized changes to organic N chemistry across fire severity gradients resulting from two wildfires that burned lodgepole pine (Pinus contorta) forest along the Colorado/Wyoming border, USA. One representative gradient was selected for high-resolution analysis based on results from bulk data (total C and N, and pH). Mineral soils were collected from two depths in low, moderate, and high severity burned areas and adjacent, unburned locations one year following the Ryan and Badger Creek fires. Nuclear magnetic resonance spectroscopy and 21 tesla ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry analysis showed that N content and aromaticity of water-extractable SOM (0–5 ​cm depth) increased with burn severity, while minimal changes to 5–10 ​cm depth were observed. Heterocyclic N species are generally higher in toxicity compared to their non-nitrogenated counterparts, which prompted soil toxicity measurements. Complementary Microtox® analysis revealed a positive relationship between increased fire severity and increased soil toxicity to Aliivibrio fischeri (microbial test species). These findings add to our molecular-level understanding of organic C and N responses to wildfire severity, with likely implications for nutrient cycling, forest recovery and water quality following severe wildfire.

Effects of selenite on the responses of lettuce (Lactuca sativa L.) to polystyrene nano-plastic stress

Nowadays, nano-plastics are widespread in agricultural soils and could be uptaken by crops to cause an increased risk for food safety. As a beneficial element for plants, selenium (Se) can alleviate oxidative damages under various environmental stresses (eg. heavy metals, heat, cold). This study investigated the single and co-applications of nano-size polystyrene (PS) (80 nm and 200 nm) and selenite (0.8 ppm and 5 ppm) in lettuce (Lactuca sativa L.). Results showed nano-PS significantly decreased the root-shoot fresh biomass ratios, inhibited physiological functions in roots and leaves (e.g. root length, chlorophyll content and net photosynthetic rate), as well as stimulated the activities of the antioxidant enzymes in roots and shoots with greater toxicity at the smaller particle size (80 nm). However, both exogenous selenite applications significantly alleviated the above toxic effects of nano-PS in lettuces, especially at a high Se level of 5 ppm. Regression Path Analysis (RPA) revealed that regulation of chlorophyll levels by Se might be a key mechanism for counteracting PS stress in lettuces, which led to the increase in indigenous defense capacity. The present findings provide a novel but safer and cleaner agricultural strategy to alleviate or minimize nano-plastics toxicity in agricultural soils for staple crops and vegetables via application of Se.

Impact of soil treatment with Nitrilo Triacetic Acid (NTA) on Cd fractionation and microbial biomass in cultivated and uncultivated calcareous soil.

The aim of this study was to evaluate the effectiveness of nitrilotriacetic acid (NTA) on cadmium (Cd) fractions and microbial biomass in a calcareous soil spiked with Cd under cultivated (Zeamays L.) and uncultivated regime subject to soil leaching condition. Expanding investigations related to soil-plant interactions on metal-contaminated soils with insights on microbial activity and associated soil toxicity perspective provides novel perspectives on using metal-chelating agents for soil remediation. The experimental factors were three levels of Cd contamination (0, 25, and 50mgkg-1 soil) and three levels of NTA (0, 15, and 30mmol L-1) in loamy soil under maize-cultured and non-cultured conditions. During the experiment, the adding NTA and leaching processes were performed three times. The results showed that the amount of leached Cd decreased in cultivated soil compared to uncultivated soil due to partial uptake of soluble Cd by plant roots and changes in Cd fractions in soil, so that Cd leached in Cd50NTA30 was 9.2 and 6.1mg L-1, respectively, in uncultivated and cultivated soils. Also, Cd leached in Cd25NTA30 was 5.7 and 3.1mg L-1 respectively, in uncultivated and cultivated soils. The best treatment in terms of chemical and microbial characteristics of the soil with the high percentage of Cd removed from the soil was Cd25NTA30 in cultivated soil. In Cd25NTA30 compared to Cd25NTA0 in cultivated soil, pH (0.25 unit), microbial biomass carbon (MBC, 65.0mgkg-1), and soil respiration (27.5mg C-CO2 kg-1 24h-1) decreased, while metabolic quotient (qCO2, 0.05) and dissolved organic carbon (DOC, 20.0mg L-1) increased. Moreover, the changes of Cd fractions in Cd25NTA30 in cultivated soil compared to uncultivated soil were as follows; the exchangeable Cd (F1, 0.27mgkg-1) and Fe/Mn-oxide-bounded Cd (F4, 0.15mgkg-1) fractions increased, in contrast, carbonate-Cd (F2, 2.67mgkg-1) and, organically bounded Cd (F3, 0.06mgkg-1) fractions decreased. NTA had no significant effect on the residual fraction (F5). The use of NTA, especially in calcareous soils, where most of the Cd is bound to calcium carbonate, was able to successfully convert insoluble fractions of Cd into soluble forms and increase the removal efficiency of Cd in the phytoremediation method. NTA is a non-toxic chelating agent to improve the accumulation of Cd in maize.

The impact of the ecological and climatic characteristics of the territory on the condition of the housing stock

The problem of environmental pollution is relevant at the present time. Any enterprise is a potential source of environmental pollution, and the production of road construction materials is one of the enterprises that pose a significant danger to the environment. As an example, we chose Primasfalt LLC, which is one of the main enterprises serving the roads of the city of Vladivostok. At all stages of the preparation of asphalt concrete mixtures, pollutants are released. Toxic substances accumulate in the atmospheric air, then fall on the ground in the form of liquid and solid precipitation, penetrating into the soil, groundwater is polluted, and the balance of nutrients in the soil is disturbed. In the course of the study, an assessment was made of the impact of asphalt concrete production on the condition of soils through the use of test objects — living organisms that are able to respond to environmental changes. The test object was oats, the most common and widely available bioindicator of soil conditions. Sampling points are located within the sanitary protection zone of the enterprise. When sampling, the climatic characteristics of the city of Vladivostok were taken into account. The results of the study showed that high toxicity of soils is observed at points located in the zone of maximum values of wind speed and its frequency. With the help of bioindicator organisms, it is possible to quickly and inexpensively analyze the state of the natural environment. Assessing the activity of an asphalt concrete plant with the help of biological objects makes it possible to identify the intensity of its impact not only within the framework of normative values that are aimed specifically at humans, but also at biological objects in general, which determines the relevance of the chosen topic. The purpose of the study is to assess the level of soil toxicity within the regulatory sanitary protection zone of the LLC Primasfalt enterprise in the city of Vladivostok, Primorsky Krai.

Soil toxicity in a protected area in Brazil: Cytotoxic, genotoxic, and toxic effects

The Campos de Palmas Wildlife Refuge (CPWR) (Brazil) is a full protection Conservation Unit (CU) formed by private properties, where the use of land and natural resources are allowed sustainably according to the rules of the CU Management Plan. Inadequate practices of land use and occupation within this CU can affect its quality and the organisms that depend on them. Considering the above, the objective of the present study was to biomonitor different land uses and occupations within the CPWR and its surroundings, during the four seasons of a year, using the bioindicators Allium cepa (cytotoxicity and genotoxicity tests) and Eisenia fetida (leakage test). The soil samples were collected in areas of silviculture, agriculture, and native grasslands within the CU and agriculture outside the limits of the CPWR. The use by silviculture (spring) and native grassland (summer) showed cytotoxic effects for A. cepa. The use by agriculture outside the CPWR (spring) showed genotoxic effect and stimulation of mitotic cell division. For the animal bioindicator, the use by agriculture within the CPWR (winter), native grassland (autumn and spring), silviculture (autumn and spring), and agriculture outside the CU (spring) showed a toxic effect. A PCA analysis showed a correlation between the results of toxicity, cytotoxicity, and genotoxicity with the presence of macronutrients and metals in the evaluated soil samples. Possibly influenced by their soil composition characteristics (silviculture and native grassland) or the management of agricultural areas. In addition, samples from the rainy season (spring) showed higher ecotoxicity. These results show that biomonitoring through different organisms is important for evaluating environmental quality and indicate the need for the implementation of preventive measures in the CPWR to avoid the toxic, cytotoxic, and genotoxic effects found. They also ensure the integrity of this CU and the active protection of the environment and biodiversity.

Soil polluted with nano ZnO reveals unstable bacterial communities and decoupling of taxonomic and functional diversities

Due to relentless production and disposal of nano zinc oxide (nZnO), it has become critical to comprehend the serious risks large-scale accumulation of nZnO pose to bacterial communities in soil. The primary objective was to evaluate the changes in bacterial community structure and associated functional pathways through predictive metagenomic profiling and subsequent validation through Quantitative Realtime PCR in soil spiked with nZnO (0, 50, 200, 500 and 1000 mg Zn kg−1) and similar levels of bulk ZnO (bZnO). The results revealed that soil microbial biomass-C, -N, -P, soil respiration and enzyme activities decreased markedly at higher ZnO levels. The alpha diversity decreased with increasing ZnO level, with more impact under nZnO, while beta diversity analyses indicated a distinct dose- dependent separation of bacterial communities. The dominant taxa including Proteobacteria, Bacterioidetes, Acidobacteria and Planctomycetes significantly increased in abundance, while Firmicutes, Actinobacteria and Chloroflexi decreased in abundance with elevated nZnO and bZnO levels. Redundancy analysis indicated that changes in bacterial community structure instilled a greater dose- rather than size- specific response on key microbial parameters. Predicted key functions did not show a dose- specific response, and at 1000 mg Zn kg−1, methane metabolism as well as starch and sucrose metabolism were attenuated, while functions involving two component systems and bacterial secretion systems were enhanced under bZnO indicating better stress avoidance mechanism than under nZnO. Realtime PCR and microbial endpoint assays confirmed the metagenome derived taxonomic and functional data, respectively. Taxa and functions that varied substantially under stress were established as bioindicators to predict nZnO toxicity in soils. Taxon-function decoupling indicated that the soil bacterial communities deployed adaptive mechanisms under high ZnO, with lesser buffering capacity and resilience of communities under nZnO.

Vineyard floor management intensity impacts soil health indicators and plant diversity across South Australian viticultural landscapes

Throughout the last thirty years, major shifts in vineyard floor management have been observed. Challenges initially posed by intensive tillage included high rates of soil erosion and the degeneration of soil structure and soil organic matter, which lead viticulturists to depend more heavily on herbicide use as an effective weed control strategy. However, an increase in herbicide persistence and toxicity in water, soils, and grapevines, increasing resistance of common weeds; and pressure from consumers and regulators to reduce their use is directing a shift towards an overall reduction in herbicide usage. This has led to more frequent tillage to manage vegetation in vineyards, while in some instances, cultural practices including slashing and animal grazing are used solely or in conjunction. However, little is known about the holistic effects of these varying practices on vineyard soils and biodiversity across landscapes in Australia. Thus, to comparatively assess the environmental impacts of different floor management practices, soil health indicators and plant dynamics were seasonally measured in the mid- and under-vine rows at twenty-four vineyard sites and four native sites in the Barossa Valley, Eden Valley, and McLaren Vale, all located in South Australia, where different intensities of floor management were implemented. Vineyard sites were categorised based on the frequency of herbicide and/or tillage passes particularly in the under-vine area into Low (no annual management passes), Medium (one annual management pass), and High (two to four annual management passes) intensity groups. Findings revealed similarities in the vineyard mid-rows across the management intensities, yet the under-vine rows displayed many differences; in particular, there were more plant species, higher plant coverage, and greater plant biomass in the Low management intensity group. Furthermore, as management intensity decreased, the relative richness of ruderal plant species also decreased, giving way to a plant community mainly comprised of slow-growing, perennial Poaceae and Fabaceae species in the Low-intensity management group. These differences in plant dynamics drove a suite of soil responses including faster water infiltration, higher soil ammonium-N and total nitrogen, and a tendency of higher soil gravimetric water content at the time of sampling. These results suggest that after an initial period of establishing these more extensive vineyard floor management practices, low levels of soil disturbance in the under-vine rows may contribute positively to improving natural ecosystem synergy and functionality between soil and plants. Therefore, our findings lend insights into how the varying intensity of floor management practices, rather than differing management ideologies per se, across a viticultural landscape can be intrinsic supporters of agroecosystem resilience under South Australian conditions.

Bioprospecting acid- and arsenic-tolerant plant growth-promoting rhizobacteria for mitigation of arsenic toxicity in acidic agricultural soils.

Widespread use of chemical fertilizers and falling productivity in traditional agricultural practices has led to the biodiversity hotspot of North-Eastern region of India to face imminent threat to soil nutrients and biodiversity. The present work aimed to isolate rhizobacteria from Oryza sativa L. to evaluate their plant growth-promoting traits like indole, ammonia, siderophore production, and phosphate solubilization followed by in vitro plant growth promotion and anti-fungal assessment against Curvularia oryzae. Moreover, presence of heavy metals such as arsenic in chemical fertilizers and in groundwater contributes to arsenic contamination of agricultural soil. Taking this into consideration for the present study, the background metal content of the bulk soil, roots and grains of rice was measured. Arsenic tolerance of the rhizobacterial isolates was assessed using different concentrations of arsenite- and arsenate-supplemented media. 16S rRNA gene sequencing and phylogenetic tree analysis identified the isolates as Bacillus paramycoides, B. albus, B. altitudinis, B. koreensis, B. megaterium, B. wiedmannii, B. paramycoides, Chryseobacterium gleum, Stenotrophomonas maltophilia and Pseudomonas shirazica. Considering the acidic nature of the paddy growing soil, the growth kinetics of the isolates were monitored in acid and arsenic-supplemented conditions for 48h of growth. Few isolates showed potent anti-fungal activity against the late blight phytopathogen, Curvularia oryzae MTCC 2605, apart from being potential growth promoters. The findings open vistas for the mass production of the characterized PGP rhizobacteria for their application in rehabilitation of the degrading arsenic contaminated paddy fields.

Geospatial pattern of topsoil pollution and multi-endpoint toxicity in the petrochemical area of Augusta-Priolo (eastern Sicily, Italy)

The present study was aimed at identifying geospatial patterns of pollutants including concentrations and toxicity as complex environmental mixtures, in topsoil samples close to petrochemical facilities in the heavily industrialized area of Augusta and Priolo in south-eastern Sicily (Italy). Elemental analysis of soil was conducted by ICP-MS for 23 metals and 16 rare earth elements (REEs). Organic analyses were primarily focused on polycyclic aromatic hydrocarbons (PAHs) (16 parent homologs) and total aliphatic hydrocarbons (C10 – C40). Topsoil samples were tested for toxicity in multiple bioassay models including: 1) developmental defects and cytogenetic anomalies in sea urchin Sphaerechinus granularis early life stages; 2) growth inhibition of diatom Phaeodactylum tricornutum; 3) mortality in nematode Caenorhabditis elegans; and 4) induction of mitotic abnormalities in onion Allium cepa. Samples collected at sites closest to defined petrochemical facilities were highest in select pollutants and correlated with biological effects in different toxicity endpoints. A noteworthy finding was the increased level of total REEs in sites closest to petrochemical facilities, suggesting their contributions to identifying petrochemical sources of pollutants to the environment. The combined data obtained in the different bioassays allowed exploration of geospatial patterns of effect in biota as a function of contaminant levels. In conclusion, this study provides consistent data of soil toxicity, metal and REE contamination at Augusta-Priolo sampling sites, and may provide an appropriate baseline for epidemiological studies on high incidences of congenital birth defects in the area and identification of at-risk localities.

Characterization of Soil Toxicity in Kinkazi, Kitombe and Thiende Villages Affected by Oil Activities in Muanda and Potential Risk of Chemical Poisoning

Aims: Discharges from oil exploitation contain very toxic and persistent organic and inorganic environmental pollutants. The present study aims to characterize the ecotoxicity of the soils of these three villages subjected to oil exploitation activities.
 Study Design: This research consists of four parts, an introduction with literature review, a description of the study environment, the methods used and finally the results obtained.
 Place and Duration of Study: In order to assess the impacts due to oil exploitation activities on the soil, a study was carried out on six soil samples taken from the villages Kinkazi, Kitombe and Thiende during the month of November 2022 in the territory of Muanda, Kongo Central, D.R. Congo.
 Methodology: The soil samples were prepared in the laboratory according to standard procedures and a series of ecotoxicological tests were carried out with the analysis of some physico-chemical parameters using a Multiparameter. The data collected was processed and analysed with Excel 2010 software.
 Results: The soils of the Kinkazi, Kitombe and Thiende villages, like dumping grounds for pollutants from oil activities, are and represent a risk of chemical poisoning for the population. The inhibitory dose (ID50) varies from 26.25 to 36 g/g indicating the toxicity of these soils to Hibiscus asper seeds and the germination index obtained gives an average of around 58.7%.
 Conclusion: The ecotoxicological impact of oil activities on the soil represents a risk of chemical poisoning for the local population of Muanda given that these polluted soils are primarily used for agriculture and the species Hibiscus asper is one of the most popular species for crops market gardeners in the region.

Role of Nutrients in Plants, Its Deficiency and Management

Plants like all living beings need energy source. The energy needed by the plants are uptaken in the form of 17 essential elements. Among which Carbon, hydrogen, and oxygen are derived from surrounding. The remaining 14 essential necessary elements are supplied either from rhizosphere and soil organic matter or by important organic or inorganic fertilizers or value added soil amendments. Plants start showing nutrient deficiency when they do not get the necessary nutrients. More nutrient use can also show poor growth because of toxic chemicals in soil. So, required amount of use and the placement of nutrients is necessary. Soil and plant tissue tests have been developed to assess their’ nutrient content. By analysis, plant scientists determined the nutrient need of plant in a given soil. In addition to the levels of available nutrients, soil pH shows its role in nutrient availability and elemental toxicity in soil. In the majority, disease effect in crop plants has been reduced by fertilizer application. This is due to the host plant tolerance or resistance mechanisms involve these nutrients. When the plants were deficient, the application of nutrients significantly reduced disease.

Plant Growth-Promoting Rhizobacteria (PGPR) Assisted Bioremediation of Heavy Metal Toxicity.

Due to a variety of natural and anthropogenic processes, heavy metal toxicity of soil constitutes a substantial hazard to all living beings in the environment. The heavy metals alter the soil properties, which directly or indirectly influence the agriculture systems. Thus, plant growth-promoting rhizobacteria (PGPR)-assisted bioremediation is a promising, eco-friendly, and sustainable method for eradicating heavy metals. PGPR cleans up the heavy metal-contaminated environment using various approaches including efflux systems, siderophores and chelation, biotransformation, biosorption, bioaccumulation, precipitation, ACC deaminase activity, biodegradation, and biomineralization methods. These PGPRs have been found effective to bioremediate the heavy metal-contaminated soil through increased plant tolerance to metal stress, improved nutrient availability in soil, alteration of heavy metal pathways, and by producing some chemical compounds like siderophores and chelating ions. Many heavy metals are non-degradable; hence, another remediation approach with a broader scope of contamination removal is needed. This article also briefly emphasized the role of genetically modified PGPR strains which improve the soil's degradation rate of heavy metals. In this regard, genetic engineering, a molecular approach, could improve bioremediation efficiency and be helpful. Thus, the ability of PGPRs can aid in heavy metal bioremediation and promote a sustainable agricultural soil system.

Genetic diversity of wild barley (<i>Hordeum spontaneum</i> K. Koch) in the context of resistance to toxic aluminum ions

Background. The problem of resistance to aluminum toxicity of soils is very relevant for the cultivated type of barley. The area of acidic soils in Russia is about forty percent of the total area of arable land, so the toxicity of aluminum is one of the main factors that reduce the yield of barley. The study of wild relatives of the main crops, including barley, is of considerable interest for the development of stress-resistant cultivars. Wild barley Hordeum spontaneum K. Koch has biological characteristics similar to the cultivated H. vulgare L., grows in various ecogeographic zones, and is well adapted to local soil and climate conditions. All this makes it possible to use it as a new donor of source material for breeding high-yielding cultivars adapted to certain environmental conditions. The objective of this work was to search for H. spontaneum genotypes highly resistant to ionic (Al3+) toxicity.Materials and methods. One hundred accessions of H. spontaneum from the collection of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR) were examined. The resistance of barley accessions to toxic aluminum ions was studied at the early stages of plant development by the root test method (185 mcМ Al3+, pH 4.0) with the calculation of root and sprout length indices.Results and conclusions. The studied fragment of the wild barley collection demonstrated broad genetic diversity in terms of resistance to phytotoxic aluminum ions. Laboratory assessment allowed us to identify barley genotypes differing in the reaction of their roots and sprouts at the early phases of ontogenesis. The identified genotypes with a high level of resistance to ion stress can be used as a valuable source of genetic material to improve existing cultivars and develop new ones by introgression of foreign resistance genes.

Study of sensing mechanism of heterocyclic hazardous vapors with Metal Phthalocyanines

Industrial residues release harmful chemicals in the environment accruing toxicity in soil, air and hazard to mankind. Tetrahydrofuran (THF) and pyridine are common solvents utilized by chemical industries and research institutes. Low boiling point of these solvents amends their inhalation probability enhancing hazardous effects. Present study reports the fabrication of low power (1 V) driven chemresistors using organic dyes (Metal phthalocyanines (MPcs)) for the detection of industrial residues THF and pyridine. The variation in electrical signal of MPcs with exposure of reducing gases and tendency of THF and pyridine to donate lone pair's for charge transfer mechanism is utilized as detection principle. Aluminium Phthalocyanine hydroxide (AlPcOH), functionalized Copper and Nickel Phthalocyanines (CuPcS and NiPcS) and their various permuted combinations has been taken for sensing studies. It has been found that MPcs show higher responses towards pyridine (≈1571 times) under non-interfering and (≈169 times) at ambient conditions as compared to THF. For the case of THF, CuPcS-NiPcS composite has been found to exhibit maximum response and for pyridine CuPcS-AlPcOH-NiPcS composite exhibited maximum sensing response. AlPcOH has been found to decrease the recovery times of the composites, which is especially useful during pyridine sensing.

Remediation of Lead Toxicity Using Phosphorus in Lead‐Contaminated Agricultural Soils

AbstractPhosphorus (P) plays dual role in providing plant nutrition while suppressing lead (Pb) toxicity in soil–plant system. Remediation of lead toxicity with soluble P is a promising low‐cost soil rehabilitation technology. An incubation experiment is conducted for assessing the bioavailability of Pb and P under simultaneous application in Pb‐laden soils. The treatments consist of four Pb levels, 0, 5, 10 and 20 mg kg−1 soil, and four P levels, 0, 10, 20 and 30 mg kg−1 soil, with five periods of incubation (0, 7, 15, 30 and 60 days) arranged in a 4 × 4 × 5 factorial design. The important physical, physicochemical and chemical characteristics of soil samples are analyzed. Bioavailable P and Pb contents of the soil samples after incubation with Pb and/or P are determined. The results indicate that Pb×P interactions significantly decrease bioavailable soil‐Pb concentrations by 38.9–43.9%. Likewise, interactions of Pb×day and P×day significantly reduce soil‐Pb concentrations by 33.1–35.1 and 31.8–33.6% at different levels of Pb and P spiking, respectively. A ready reckoner is developed using the antagonism manifestation of Pb and P in soil, which suggests the administration of P doses with respect to Pb‐loading and time elapsed to rejuvenate Pb‐contaminated soils for healthy crop production.

Remediation of Cd-contaminated soil by electrokinetics coupled with the permeable reactive barrier from immobilized yeast

Yeast was used to prepare permeable reactive barrier (PRB) with immobilized microbial technology, and the electrokinetics coupled with the immobilized yeast PRB (IMEK-PRB) was established to remediate Cd-contaminated soil. The effect of the different PRBs prepared by immobilized microbial technology on Cd removal was explored. The voltage gradient had influence on the removal of Cd, and the removal reached as high as 53.70 % at a voltage gradient of 2.5 V/cm. The lowest removal about 34.12 % was obtained with yeast pellets prepared by the embedding method used as PRB. The yeast in PRB was partially broken and adhered, and the intensity of the absorption peak of the group analyzed with infrared spectra and the crystal diffraction peak from X-ray diffraction changed, leading to a decrease in its activity. The average removal of Cd increased by >10 % when fly ash-based yeast pellets prepared with the adsorption-embedding method, and fly ash-adsorbed yeast prepared by the adsorption method were used as PRB. IMEK-PRB remediation would greatly reduce the toxicity of Cd-contaminated soil, weaken harmful effects on the soil environment and reduce environmental risks. The fly ash-based yeast pellets used in IMEK-PRB have great application prospects for the remediation of Cd-contaminated soil.

Responses and detoxification mechanisms of earthworm Amynthas hupeiensis to metal contaminated soils of North China

Metal contamination is widespread, but only a few studies have evaluated the toxicological risks of metals (Cd, Cu, and Pb) in earthworms from farmlands in North China (Hebei province). Amynthas hupeiensis, the dominant species in the study area, was used to determine the responses and detoxification mechanisms of uncontaminated (CK), and low (LM)-, and high (HM)-metal-contaminated soils following 7-, 14-, and 28-days exposure. Metal toxicity in LM and HM soils inhibited the biomass of A. hupeiensis. The concentrations of Cd in A. hupeiensis bodies indicated accumulated Cd appeared to remain steady with prolonged exposure, while Cu/Pb increased significantly with soil levels. Bioaccumulation occurred in the order Cd > Pb > Cu in LM soil, and in the order Cd > Cu ≈ Pb in HM soil, which was attributed to differences in available fractions between LM and HM soils. Physiological levels of biomarkers in A. hupeiensis were determined, including total protein (TP), glutathione (GSH), glutathione peroxidase (GPx), acetylcholinesterase (AChE), and malondialdehyde (MDA). Deviations in GSH, GPx, and AChE were considered to denote sensitive biomarkers using the IBRv2 index. Metabolomics data (1H nuclear magnetic resonance-based) revealed changes in metabolites following 28-days exposure to LM and HM soils. Differences in metabolism in A. hupeiensis following exposure to LM and HM were related to energy metabolism, amino acid biosynthesis, glycerophospholipid metabolism, inositol phosphate metabolism, and glutathione metabolism. Metal stress from LM and HM soils disturbed osmoregulation, resulting in oxidative stress, destruction of cell membranes and inflammation, and altered levels of amino acids required for energy by A. hupeiensis. These findings provide biochemical insights into the physiological and metabolic mechanisms underlying the ability of A. hupeiensis to resist metal stress, and for assessing the environmental risks of metal-contaminated soils in farmland in North China.

Prediction of soil ecotoxicity against Folsomia candida using acute and chronic endpoints

ABSTRACT Soil invertebrates serve as great biological indicators of soil quality. However, there are very few in silico models developed so far on the soil toxicity of chemicals against soil invertebrates due to paucity of data. In this study, three available soil ecotoxicity data (pLC50, pLOEL and pNOEL) against the soil invertebrate Folsomia candida were collected from the ECOTOX database (cfpub.epa.gov/ecotox) and subjected to quantitative structure-activity relationship (QSAR) analysis using 2D descriptors. The collected data for each endpoint were initially curated and used to develop a partial least squares (PLS) regression model based on the features selected through a genetic algorithm followed by the best subset selection. Both internal and external validation metrics of the models’ predictions are well-balanced and within the acceptable range as per the Organization for the Economic Cooperation and Development (OECD) criteria. From the developed models, it has been found that molecular weight and presence of phosphate group, electron donor groups, and polyhalogen substitution have a significant impact on the soil ecotoxicity. The soil ecotoxicological risk assessment of organic chemicals can therefore be prioritized by these features. With the availability of additional data in the future, the models may be further refined for more precise predictions.