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The effectiveness of remediation agents in detoxification of soils contaminated with heavy metals is studied in a laboratory experiment. The objects of the study are southern tundra soils functioning under conditions of anthropogenic impacts: haplic gleysols gelic and histic fluvisols oxyaquic. The chemical ability of remediation agents to bind metals (Ni and Cu), transferring them to a sedentary state compared to the reference variants (without adding a remediation agent), is evaluated. In the experiments, remediation agents are used in three doses (D1–D3): carbonaceous (shungite), of biological origin (diatomite), and mineral remediation agents (glauconite and bentonite). To assess the immobilization of Ni and Cu in soils, acid-soluble (AS) forms (extraction of 1 N HNO3), mobile forms (ammonium acetate buffer with pH 4.8), and water-soluble forms of Ni and Cu (1 : 20 aqueous extract) are determined by inductively coupled plasma mass spectrometry. The effectiveness of soil detoxification during the application of remediation agents is evaluated by the phytotoxic effect in an express test, a response of standardized test plants (Brassica rapa CrGC and Avena sativa) represented by higher plants. A decrease in the proportion of mobile forms of Ni and Cu by 50% or more in haplic gleysols gelic is revealed when any dose of remediation agents is added. The greatest effect of reducing mobility is exerted by shungite and diatomite at a dose of D1, up to 15% Ni and Cu in histic fluvisols oxyaquic. The use of the selected remediation agents in the indicated amounts did not have a phytotoxic effect on the test plants in the experiment. [ABSTRACT FROM AUTHOR]

Environmental pollutants called polycyclic aromatic hydrocarbons (PAHs) are common contaminants with human health and environmental concerns. The 16 priority, 1-methylnaphthalene, and 2-methylnaphthalene PAHs in soil samples from agricultural farmland around River Owan, Edo State, Nigeria was determined by deploying a flame ionization detector with gas chromatography. The total concentration ∑16PAHs of the soil samples is in the range of 0.198 - 0.518µg/kg, ∑18PAHs 0.23 - 0.56 µg/kg, ∑LMW PAHs 0.095 - 0.205 µg/kg while the ∑HMW PAHs 0.087 - 0.348 µg/kg. The Concentration of ∑PAHs is in this order: SO1>SO4>SO5>SO6>SO2>SO7>SO3. The ratio of the LMW/HMW PAHs percentage is 43% - 57%. The ∑7cPAHs were in the range of 0.032 - 0.245 µg/kg with a mean value of 0.133 µg/kg. The ∑TEQ range is 0.004 - 0.139 while the BaP-EQ of the soil samples is 0.285 µg/kg indicating no risk. The diagnostic ratio showed more of the pyrogenic source. The percentage of petrogenic to pyrogenic in the ratio of Ant/(Ant + Phe) is 43% to 57%. The ratio of Flt/(Flt + Pry) is above >0.1 meaning they are from pyrogenic sources. The value of the children's incremental lifetime cancer risk (ILCR) ranged from 6.43 x 10-8 - 6.46 x 10-6, 2.58 x 10-8 - 2.59 x 10-6, and 1.09 x 10-12 - 1.10 x 10-10 for dermal, ingestion and inhalation while for adult: 2.43 x 10-8 - 2.44 x 10-6, 1.37 x 10-8 - 1.37 x 10-6, and 9.27 x 10-13 - 9.32 x 10-11 for same routes of exposure respectively showing a negligible risk. [ABSTRACT FROM AUTHOR]

Although research on microplastics (MPs) interactions with other soil pollutants is increasingly becoming available, most studies do not consider risks to soil fertility or plant growth. This review aims: 1) to summarize the results of current studies on interactions between MPs, heavy metals, and organic pollutants; and 2) subsequently evaluate risks to the soil-plant nexus. Available-literature shows that polypropylene, polyethylene and polylactic acid increase cadmium (Cd) bioavailability and subsequently reduce root growth. Such effects are not evident in sandy or clay soils due to the formation of CdCO3 and iron-oxide by altered bacterial communities that stabilize Cd contamination. Chronic instead of short-term exposure to polystyrene in copper (Cu) - polluted soils decreases crop yield. With coexistence of MPs and lead (Pb) in soil, the uptake of Pb in crops increases, causing altered malondialdehyde content and superoxide dismutase and guaiacol peroxidase activities. Moreover, co-toxicity of polystyrene or polytetrafluoroethylene with arsenic (As) decreases root biomass, photosynthesis rate and the chlorophyll-a content. In alkaline soil, polyvinyl-chloride could decrease the bioavailability of MeHg due to changes in the abundance of Proteobacteria, and Firmicutes. We also found strong interactions between MPs and organic pollutants. Polystyrene decreases negative impacts of sulfamethazine on bacterial diversity, and structure in soil. Polyethylene, polyvinyl-chloride and polystyrene have a strong adsorption capacity for 17β-estradiol. This implies that 17β-estradiol toxicity can be reduced by these MPs. At low concentrations, polyethylene, polypropylene, and polystyrene have low affinity to diazepam. In conclusion, serious ecological risks are associated with MPs and other pollutants' interactions to soil-plant system.

Soil organic matter can protect plants and microorganisms from toxic substances. Beyond the tolerance limit, the toxicity of petroleum pollution to soil organisms may increase rapidly with the increase of petroleum content. However, the method for evaluating the petroleum tolerance limit of soil organic matter (SOM) is still lacking. In this study, the petroleum saturation limit in SOM was first evaluated by the sorption coefficient (Kd) of 1,2-dichlorobenzene (DCB) from water to soils containing different petroleum levels. The sorption isotherm of dichlorobenzene in several petroleum-contaminated soils with different organic matter content and the microbial toxicity test of several petroleum-contaminated soils were determined. It is found that when the petroleum content is about 5% of the soil organic matter content, the sorption of petroleum to organic matter reached saturation limit. When organic matter reaches petroleum saturation limit, the sorption coefficient of DCB by soil particles increased linearly with the increase of petroleum content (R2 > 0.991). The results provided important insights into the understanding the fate of petroleum pollutants in soil and the analysis of soil toxicity. [ABSTRACT FROM AUTHOR]

The number of soil microorganisms affect the fertility of the soil and the processes occurring in the soil microflora. An urgent research problem is the rationale for the use of intensive technologies for the cultivation of sweet corn using progressive methods for obtaining a highly productive crop based on the principles of resource conservation, biologization and ecologization. The purpose of the research is to study the toxicity and biological activity of the soil after sowing sweet corn. The tasks are to determine the biological activity and toxicity of the soil, and comparative impact of agricultural practices in the study of soil toxicity. Two-factor experiment in quadruple repetition. The experiments were carried out on the farm enterprise of Popov S.A., the Chernoyarsky district of the Astrakhan region. The research period was 2009…2015. Determination of biological activity and toxicity was carried out at the beginning of the research in 2009 and 2015. According to the assessment of the intensity of the destruction of cellulose on O.E. Pryazhnikova’s scale biological activity was characterized as strong. A close correlation dependence on experience factors was noted, the relationship between the signs was high and direct. When determining the toxicity of the soil, we came to the conclusion that at the beginning of the research favorable conditions for the development of the studied crop were formed on soils cultivated by moldboard cultivation. According to zero tillage, an increase in soil toxicity was observed, which was expressed in a decrease in seed germination, the mass of seedlings. Revisited in 2015. Soil toxicity after zero tillage decreased in all variants, seed germination increased, on average, by 5...8%. As a result of the accumulation of plant residues on the soil surface, an upper humus layer was formed, leading to a constant penetration of ai r into the soil.

Purpose Olive mill waste sludge (OMWS) is a solid by-product resulting from olive oil extraction, OMWS is usually left decanting in landfills causing environmental pollution and a significant loss of recyclable organic resources. This study aims to evaluate the feasibility of producing an organic amendment through treating OMWS with solar drying (SDy), which is a low-cost method, highly adapted to semi-arid and low-income countries.Method We investigated the effect of 90 days SDy on OMWS physico-chemical properties, then the agronomic efficiency of the resulting product was assessed under greenhouse conditions, using Zea mays as a crop model.Results The SDy treatment significantly reduced OMWS initial moisture and the C/N ratio, while the nutrient content of the final product was improved. Pot trial under greenhouse conditions revealed that the application of SDy-OMWS improved the soil physico-chemical properties. The initial application decreased soil pH from 8.19 to 7.06, and soil phosphorus (P), potassium (K), iron (Fe) and zinc (Zn) increased by 209%, 162.4%, 290% and 270% respectively compared to the unamended control. SDy-OMWS application initially induced a delayed seed germination and plant growth at early stages, which was followed by a significant improvement of plant above and below ground traits, including photosynthetic activity, stomatal conductance, and root parameters (RL, RSA and RV).Conclusion Overall, SDy significantly reduced the C/N ratio, moisture, and improved the nutrient content of OMWS. Despite improving soil fertility, SDy-OMWS application negatively affected the plant development at early stages. However, such effect was completely alleviated at the end of the experiment.

Agricultural industry is facing huge crisis due to fast changing climate, decreased soil fertility, macro and micronutrient insufficiency, misuse of chemical fertilizers and pesticides, and heavy metal presence in soil. With exponential increase in world's population, food consumption has increased significantly. Maintaining the production to consumption ratio is a significant challenge due to shortage caused by various issues faced by agricultural industry even with the improved agricultural practices. Recent scientific evidence suggests that nanotechnology can positively impact the agriculture sector by reducing the harmful effects of farming operations on human health and nature, as well as improving food productivity and security. Farmers are combining improved agricultural practices like usage of fertilizers, pesticides etc. with nano-based materials to improve the efficiency and productivity of crops. Nano technology is also playing a significant role improving animal health products, food packaging materials, and nanosensors for detecting pathogens, toxins, and heavy metals in soil among others. The nanobased materials have improved the productivity twice with half the resources being utilized. Nanoparticles that are currently in use include titanium dioxide, zinc oxide, silicon oxide, magnesium oxide, gold, and silver used for increasing soil fertility and plant growth. Crop growth, yield, and productivity are improved by controlled release nanofertilizers. In this review we elaborate on the recent developments in the agricultural sector by the usage of nanomaterial based composites which has significantly improved the agricultural sector especially how nanoparticles play an important role in plant growth and soil fertility, in controlling plant diseases by the use of nanopesticides, nanoinsecticides, nanofertilizers, Nanoherbicides, nanobionics, nanobiosensors. The review also highlights the mechanism of migration of nanoparticles in plants and most importantly the effects of nanoparticles in causing plant and soil toxicity. [ABSTRACT FROM AUTHOR]

Purpose Olive mill waste sludge (OMWS) is a solid by-product resulting from olive oil extraction, OMWS is usually left decanting in landfills causing environmental pollution and a significant loss of recyclable organic resources. This study aims to evaluate the feasibility of producing an organic amendment through treating OMWS with solar drying (SDy), which is a low-cost method, highly adapted to semi-arid and low-income countries. Method We investigated the effect of 90 days SDy on OMWS physico-chemical properties, then the agronomic efficiency of the resulting product was assessed under greenhouse conditions, using Zea mays as a crop model. Results The SDy treatment significantly reduced OMWS initial moisture and the C/N ratio, while the nutrient content of the final product was improved. Pot trial under greenhouse conditions revealed that the application of SDy-OMWS improved the soil physico-chemical properties. The initial application decreased soil pH from 8.19 to 7.06, and soil phosphorus (P), potassium (K), iron (Fe) and zinc (Zn) increased by 209%, 162.4%, 290% and 270% respectively compared to the unamended control. SDy-OMWS application initially induced a delayed seed germination and plant growth at early stages, which was followed by a significant improvement of plant above and below ground traits, including photosynthetic activity, stomatal conductance, and root parameters (RL, RSA and RV). Conclusion Overall, SDy significantly reduced the C/N ratio, moisture, and improved the nutrient content of OMWS. Despite improving soil fertility, SDy-OMWS application negatively affected the plant development at early stages. However, such effect was completely alleviated at the end of the experiment. [ABSTRACT FROM AUTHOR]

Abstract Background Most studies on plant invasion consider the enemy release hypothesis when analyzing native habitats. However, the lower performance of invasive species in the native habitats can be the result of unfavorable soil conditions in the native habitats. While soil biotic and abiotic factors have a potential to restrict the growth of invasive species in their native habitats, our understanding of belowground environment of invasive species in their native habitats is very limited. In this study, we analyzed soil characteristics associated with an exotic invasive plant, Old World Climbing Fern (Lygodium microphyllum), in its native habitat in Australia and the recipient habitat in South Florida. Rhizosphere soil samples from both habitats were analyzed for soil physical, chemical and biological characteristics. Results Soil characteristics in the recipient habitats were significantly different compared to those in the native habitats. Soil samples from the native habitat had low soil pH, and high concentrations of elements such as aluminum and zinc which are phytotoxic in acidic soil environments. Additionally, mycorrhizal fungi spores were more diverse in the recipient habitat in Florida compared to the native habitat in Australia. Conclusion Overall, our results indicate that growth of an invasive plant in its native habitats could be restricted by the toxic effects associated with strong soil acidity. Results from this study indicate that invasive plants not only escape from their natural herbivores but also from toxic soil environment in their native habitats.

Soil toxicity tests are commonly applied using Enchytraeus crypticus to analyze reproductive outputs. However, the traditional method for counting potworms takes a long time due to the significant number of offspring. This paper compares the conventional total counting of E. crypticus juveniles (M1) and an alternative methodology (M2). The proposed methodology (M2) uses a simple random counting method (1/4) for the partial counting of juveniles and total estimation. Chronic bioassays (21 days of exposure) were performed in tropical artificial soil (TAS) using sugarcane vinasse as a hazardous substance. Comparing the final density of juveniles recorded in M1 and M2, no statistical differences were pointed out in either one. Applying analyses based on effective concentration (EC10 and EC50), no statistical differences were identified there either. The t-test showed that there was no statistical difference between the counting methods (M1 and M2) in each treatment (control and dilutions). Moreover, we ran the Tukey test for M1 and M2 methods separately and observed that 100 % of the vinasse showed a statistical difference compared to the control treatment in both (p ≤ 0.05), affirming that independent of the counting method, the ecotoxicological outputs were similar. Therefore, the proposed alternative is a suitable method for bioassay using. E. crypticus in tropical artificial soil, decreasing to 1/4 the total time required for counting. [ABSTRACT FROM AUTHOR]

In this study, light intensities of Aliivibrio fischeri obtained from soil suspension and its filtrate were compared using field soils contaminated with heavy metals. The soils collected from rice paddy and forest had different soil textures with either high or low silt/clay content. The correlation between soil toxicity and soil solution toxicity for A. fischeri showed a high linearity in sandy soils with the slope of 0.586 (determination coefficient; R2 = 0.709). Meanwhile, a lower correlation in silty/clay soils with the slope of 0.154 (R2 = 0.067) was observed. When a solid phase bioluminescence inhibition test is carried out using soil suspension with a high silt/clay content, a large amount of A. fischeri seems to adhere to microparticles and/or microaggregates. It may result in the change of light intensity (i.e., distorted toxicity test result) that could not be corrected by the modified basic solid phase test protocol, and thus the toxicity is likely to be overestimated. Such alteration in the light intensity could be partially overcome using a regression equation accounting for microbial loss by adhesion. With the correction for microbial adhesion, the correlation between soil toxicity and soil solution toxicity in the selected soil samples with high silt/clay contents increased from 0.182 (R2 = 0.130) to 0.571 (R2 = 0.602). It is expected that soil toxicity can be evaluated through the prediction of soil solution toxicity after the proper correction of microparticles effects. [ABSTRACT FROM AUTHOR]

An explanatory study was carried out to divulge the sources, contamination level of different classes of Polycyclic Aromatic Hydrocarbons (PAHs) distribution and the impact of vehicular traffic on the roadside soil by assessing incremental lifetime cancer risk at each site to understand the potential health risk of nearby residents along the National Highway-2 Delhi–Kolkata India. Comparison of the cancer risk assessment was performed using Monte Carlo simulation for the entire study area. The results revealed 90% cancer risk value of 6.40 × 10−5 and 6.5 × 10−5 for children and adults, respectively, whereas, without simulation the Total Cancer Risk (TCR) for adults was 6.925 × 10−5 and 6.220 × 10−5 for children, observed maximum at the location (S5). The dilemma of risk assessment indicating profoundly contaminated soil. Comparison of PAHs concentration with the background values of PAHs ranged from 1.478 to 27.493 mg kg−1. The (IP/BgP) ratio specified that the PAHs content of the highway roadside sample is preponderate by diesel vehicle emission, biomass combustion and coal combustion. The study clearly revealed and advocated the influence of organic and inorganic pollution, which aggravates and causes health issues to the nearby inhabitants. This study could also be advantageous to similar consequences seen elsewhere in the world. [ABSTRACT FROM AUTHOR]

Background: Most studies on plant invasion consider the enemy release hypothesis when analyzing native habitats. However, the lower performance of invasive species in the native habitats can be the result of unfavorable soil conditions in the native habitats. While soil biotic and abiotic factors have a potential to restrict the growth of invasive species in their native habitats, our understanding of belowground environment of invasive species in their native habitats is very limited. In this study, we analyzed soil characteristics associated with an exotic invasive plant, Old World Climbing Fern (Lygodium microphyllum), in its native habitat in Australia and the recipient habitat in South Florida. Rhizosphere soil samples from both habitats were analyzed for soil physical, chemical and biological characteristics. Results: Soil characteristics in the recipient habitats were significantly different compared to those in the native habitats. Soil samples from the native habitat had low soil pH, and high concentrations of elements such as aluminum and zinc which are phytotoxic in acidic soil environments. Additionally, mycorrhizal fungi spores were more diverse in the recipient habitat in Florida compared to the native habitat in Australia. Conclusion: Overall, our results indicate that growth of an invasive plant in its native habitats could be restricted by the toxic effects associated with strong soil acidity. Results from this study indicate that invasive plants not only escape from their natural herbivores but also from toxic soil environment in their native habitats. [ABSTRACT FROM AUTHOR]

Background and Purpose: Technogenic load is considered to be one of the major factors which destabilize forest ecosystems. The impact of chronic aero technogenic pollution near large industrial centers severely affects the plants in these areas; thus, plants cannot fulfill their aesthetic and air-cleaning role. Therefore, many studies have been carried out on technogenic pollution and particularly on magnesite pollution. The aim of the study is to investigate characteristics of the Scotch pine natural regeneration process under the forest canopy in magnesite pollution conditions. Materials and Methods: The research was carried in an aero-technogenic emission zone of Kombinat Magnezit, in South Ural, Russia. The purpose is to assess the soil suitability for reforestation in various degrees (PS-2: High pollution zone, PS-5: Average pollution zone, PS-3: Low pollution zone, PS-4: Very weak pollution zone, and PS-K: Control area) of magnesite pollution. Experimental Plots (PS) are in similar conditions regarding forest vegetation. The major factors that can influence the natural regeneration, such as the quantity of seeds produced by the parents trees, stand density (the number of trees per 1 ha), the composition of the upper horizon of the soil and height, its density, live ground cover (LGC) phytomass and pH of the upper root-inhabited soil layer have been measured. Results: The results of this study showed that in PS-K conditions a large number of seeds, thin forest litter, small phytomass of alive ground cover, and slightly acidic pH of the root zone of the soil can be found. The dense forest laying, generally composed of fresh and weakly decomposed layers, inhibits seed germination from reaching the mineral soil layer, which results in mortality. Conclusions: It was evaluated that the success of natural regeneration is effected by the stand density and the occurrence of undergrowth of Scots pine. Soil remediation can positively affect the natural rejuvenation process. Moreover, seed supplementation can play a major role in successful natural rejuvenation.

Toxicity and persistence of heavy metals, which are accumulated in the environment as the result of diverse industrial activities, represent serious environmental problem worldwide. The intense mineral extraction in mining areas has produced a large amount of waste material and tailings, which release toxic elements to the environment. The aim of the study was to determine in two time horizons (1997, 2015) the heavy metal contents of samples derived from ten sampling sites located in the former mining area of Central Spiš (Slovakia). In order to compare the level of contamination, the contamination factor (Cif), degree of contamination (Cd), and pollution load index (PLI) were computed. Spearman's correlation coefficient was used in order to detect the relationships among heavy metals. A serious situation was found for Hg, Zn, and Cd, which exceeded limit values at all sampling sites within both studied years. In 1997, the average values of contamination factor have shown very high contamination with all studied heavy metals, and moderate contamination with Co. In 2015, the study area was classified as very highly contaminated with As, Hg, Zn, Cu, considerably contaminated with Ni, Cr, Pb, and Cd, while Co contamination was not detected. Since 1997 till 2015 the pollution load index decreased by about 38%, nevertheless even then almost all sampling sites were classified as heavily polluted. Despite the fact that mining activities were stopped or limited at the beginning of the 21st century, the presence of heavy metals in soils remains at a serious level. The high level of contamination is a result of heavy metal persistence and non-biodegradability.

This study assesses the distribution, contamination and human health risks of major, minor and trace elements in the topsoil and subsoil of two informal e-waste recycling sites in Accra, Ghana. Metal concentrations in Agbogbloshie exceeded the Dutch Soil intervention values with exceedances of 72%, 57%, 57%, 38%, 16%, 2% for Cu, Zn, Pb, Ba, Cd and As respectively. Metal concentrations in Ashaiman exceeded the Dutch Soil intervention values with exceedances of 62%, 57% and 46% for Cu, Zn and Pb respectively. Geoaccumulation indices indicated that the topsoils of the burn area and dismantling areas of Agbogbloshie e-waste recycling site were strongly contaminated by Pb and uncontaminated by Cr, Fe, As and Ba. Lead (Pb) contributed greatly to non-carcinogenic ingestion hazard quotient for residents living near Agbogbloshie and Ashaiman e-waste recycling sites while arsenic (As) presented carcinogenic risks to children from the dismantling area topsoils. Non-carcinogenic risks from ingestion were significant with children being more susceptible to non-carcinogenic ingestion risks than adults. Non-carcinogenic risks from dermal exposure were negligible. Hazard quotients of Pb for children in burn area topsoils and dismantling area topsoils were 7.4–7.6-fold greater than that for adults. The mean geoaccumulation indices values of Pb and Cu indicated extreme contamination of topsoils with these elements. A "novel environmental assessment tool" based on the Agency for Toxic Substances and Disease Registry (ASTDR) total impact points confirmed Pb and Cu as the most toxic elements. • Metal contamination of E-waste impacted soils were assessed. • Topsoils were contaminated with lead (Pb), copper (Cu) and zinc (Zn). • Health risks arising from subsoils in E-waste recycling areas can be significant. • Non-carcinogenic risks from Pb was seven times greater for children than adults. • Children can suffer carcinogenic risks from oral exposure to arsenic (As). [ABSTRACT FROM AUTHOR]

Abstract Soil pollution and toxicity have been investigated in the Gardanne area (southern France) at a range of sites around a recognized pollution source, a bauxite processing plant (BPP), and a power plant (PP). Soil samples were submitted to inorganic and organic analyses and tested for toxicity in two invertebrate models. Inorganic analysis was based on determining elemental concentrations by ICP-MS, encompassing a total of 26 elements including 13 rare earth elements (REEs), of the soil samples and their leachates after 24 or 48 h in seawater. Organic analyses were performed by measuring the sums of 16 polycyclic aromatic hydrocarbons (PAHs) and of total hydrocarbons (C-10 to C-40). Bioassays were carried out on the early life stages of three sea urchin species (Arbacia lixula , Paracentrotus lividus and Sphaerechinus granularis), and on a nematode (Caenorhabditis elegans). Sea urchin bioassays were evaluated by the effects of soil samples (0.1–0.5% dry wt/vol) on developing embryos and on sperm, and scored as: a) % developmental defects, b) inhibition of sperm fertilization success and offspring damage, and c) frequencies of mitotic aberrations. C. elegans 24 h-mortality assay showed significant toxicity associated with soil samples. The effects of soil samples showed heightened toxicity at two groups of sites, close to the BPP main entrance and around the PP, which was consistent with the highest concentrations found for metals and PAHs, respectively. Total hydrocarbon concentrations displayed high concentrations both close to BPP main entrance and to the PP. Further studies of the health effects of such materials in Gardanne are warranted. Highlights • Gardanne soil showed highest metal and organic levels close to a bauxite processing plant. • Sea urchin early life stages showed highest toxicity close to BPP and a power plant (PP). • Nematode mortality bioassay showed highest toxicity close to BPP and PP. • Further investigations are warranted in Gardanne residential area. [ABSTRACT FROM AUTHOR]

Abstract The assessment of benzene, toluene, ethyl-benzene, and xylene (BTEX)-contaminated soil toxicity was performed using a sulfur-oxidizing bacteria (SOB) assay. The experiments were set up using an individual pollutant in a 25-mL bottle sealed with a rubber stopper and aluminum cap since BTEX are volatile. A large headspace volume (14 mL) was kept in the reactors to provide enough oxygen for the SOB. Soil samples were spiked with BTEX compounds in the concentration range of 1–1000 mg/kg. In reactors without BTEX compounds, approximately 85% of the theoretically required oxygen was consumed. Whereas, the reactors with benzene consumed in the range of 82–64% (5–100 mg/kg), those with toluene consumed 76–53% (1–50 mg/kg), those with ethyl-benzene consumed 44–71% (5–100 mg/kg), and those with xylene consumed 64–71% (1–10 mg/kg) of the theoretically required oxygen. The effective concentrations responsible for 50% growth inhibition (EC 50) for benzene, toluene, ethyl-benzene, and xylene detection were 130.2, 1.2, 15.2, and 0.7 mg/kg, respectively. These results suggest that this SOB-based bioassay can detect BTEX pollutants in soils. Highlights • Benzene, Toluene, Ethyl-benzene, and Xylene containing soil was assessed. • A sulfur-oxidizing bacteria (SOB) based bioassay was developed for the soil toxicity monitoring. • The SOB bioassay worked by producing sulfate with lowering pH and increasing EC. • In the presence of BTEX the sulfate production decreased. • The EC50 of BTEX was calculated as 130.2, 1.2, 15.2, and 0.7 mg/kg respectively. [ABSTRACT FROM AUTHOR]

This study explored the use of multicylindrical dielectric barrier discharge (MC–DBD) plasma technology to eliminate diesel fuel contamination from the soil. This study also assessed the environmental impact of plasma-generated reactive species on soil properties, plant growth, and the safety of microbial and human skin cells using various analytical methods. MC–DBD plasma was characterized using the current–voltage analysis and optical emission spectroscopy (OES). Gas Fourier transform infrared spectroscopy was employed to detect reactive species, such as O 3 , NO, NO 2 , N 2 O, and HNO 3, in the plasma-treated air. The diesel fuel concentration in the soil was measured before and after plasma treatment using a gas chromatography–flame ionization detector. The efficacy of the MC–DBD plasma treatment was evaluated based on soil characteristics (pH and moisture), discharge parameters (power), and reactive species (O 3 and NO x). Using only power of 30 W, the MC–DBD achieved a 94.19% removal of diesel fuel from the soil and yielded an energy efficiency of 1.78 × 10−2 m3/kWh within a 60-min treatment period. Neutral soil with a moisture content of 2% proved more effective in diesel fuel removal compared with acidic or alkaline soil with higher moisture content. O 3 was the most efficient plasma-generated reactive species for diesel fuel removal and is involved in oxidation-induced fragmentation and volatilization. Overall, the potential of the MC–DBD plasma technology for remediating diesel fuel-contaminated soils is highlighted, and valuable insights for future applications are provided. [Display omitted] • MC–DBD can remove 94.19% diesel from soil with 30 W input power. • MC–DBD can remove diesel fuel more efficiently from neutral soil than acidic/alkaline soil. • O 3 dominated NO X /other plasma-generated reactive species during diesel fuel removal. • Soil diesel-fuel removal occurs via oxidation-induced fragmentation. • Plasma-remediated soil has potential for biohealth and agricultural applications. [ABSTRACT FROM AUTHOR]

The chemical properties, ecotoxicity, and microbiome of leachates from phytomanaged Cu-contaminated soils were analyzed. The phytomanagement was carried out using Cu-tolerant poplar Populus trichocarpa × deltoides cv. Beaupré and black bent Agrostis gigantea L., aided by soil amendments, i.e., dolomitic limestone (DL) and compost (OM), alone and in combination (OMDL). Plants plus either DL or OMDL amendments reduced in leachates the electrical conductivity, the Cu concentration, and the concentration of total organic C except for the OMDL treatment, and decreased leachate toxicity towards bacteria. Total N concentration increased in the OM leachates. The aided phytostabilization increased the culturable bacteria numbers and the proportion of Cu-resistant bacteria in the leachates, as compared to the leachate from the untreated soil. Phytomanagement also enriched the microbial communities of the leachates with plant beneficial bacteria. Overall, the Cu stabilization and phytomanagement induced positive changes in the microbial communities of the soil leachates.

The eco-toxicological indicators used to evaluate soil quality complement the physico-chemical criteria employed in contaminated site remediation, but their cost, time, sophisticated analytical methods and in-situ inapplicability pose a major challenge to rapidly detect and map the extent of soil contamination. This paper describes a sensor-based approach for measuring potential (substrate-induced) microbial respiration in diesel-contaminated and non-contaminated soil and hence, indirectly evaluates their microbial activity. A simple CO2 sensing system was developed using an inexpensive non-dispersive infrared (NDIR) CO2 sensor and was successfully deployed to differentiate the control and diesel-contaminated soils in terms of CO2 emission after glucose addition. Also, the sensor system distinguished glucose-induced CO2 emission from sterile and control soil samples (p ≤ 0.0001). Significant effects of diesel contamination (p ≤ 0.0001) and soil type (p ≤ 0.0001) on glucose-induced CO2 emission were also found. The developed sensing system can provide in-situ evaluation of soil microbial activity, an indicator of soil quality. The system can be a promising tool for the initial screening of contaminated environmental sites to create high spatial density maps at a relatively low cost.

Soil organic matter can protect plants and microorganisms from toxic substances. Beyond the tolerance limit, the toxicity of petroleum pollution to soil organisms may increase rapidly with the increase of petroleum content. However, the method for evaluating the petroleum tolerance limit of soil organic matter (SOM) is still lacking. In this study, the petroleum saturation limit in SOM was first evaluated by the sorption coefficient (K d ) of 1,2-dichlorobenzene (DCB) from water to soils containing different petroleum levels. The sorption isotherm of dichlorobenzene in several petroleum-contaminated soils with different organic matter content and the microbial toxicity test of several petroleum-contaminated soils were determined. It is found that when the petroleum content is about 5% of the soil organic matter content, the sorption of petroleum to organic matter reached saturation limit. When organic matter reaches petroleum saturation limit, the sorption coefficient of DCB by soil particles increased linearly with the increase of petroleum content (R 2  > 0.991). The results provided important insights into the understanding the fate of petroleum pollutants in soil and the analysis of soil toxicity., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Abstract Silver nanomaterials (AgNMs) of various shapes and sizes are manufactured for different purposes and used as ingredients in a wide variety of products and applications. Recently, the toxicity of AgNMs has attracted significant attention. However, the effect of the shape of AgNMs (particles, wires, plates) on their toxicity in soil ecosystems remains poorly understood. In this study, we added AgNMs of different shapes and sizes (silver nanoparticles, AgNPs; 10 μm silver nanowires, 10-AgNWs; 20 μm silver nanowires, 20-AgNWs; silver nanoplates, AgPLs) to natural soil and determined their effect on the growth and reproduction of the free-living nematode, Caenorhabditis elegans. AgNPs and AgPLs were found to inhibit the growth and reproduction of C. elegans, whereas AgNWs had a negligible effect. Among these AgNMs, the results of this study suggest AgNPs are the most toxic. This confirms that the shape of AgNPs plays a significant role in their toxicity level. To the best of our knowledge, this is the first comparative analysis of the shape-dependent toxicity of AgNMs in the soil using nematode C. elegans. This study provides a scientific reference for assessing shape-dependent soil nanotoxicity. Graphical abstract Image Highlights • Silver nanomaterials of different shapes and sizes were added to natural soil. • Growth and reproduction characteristics of C. elegans. were evaluated. • Silver nanoparticles and plates inhibited growth and reproduction of C. elegans. • Nanowires had the smallest effect on growth and nanoplates were the most toxic. • The shape of silver nanomaterials appears to significantly affect their toxicity. [ABSTRACT FROM AUTHOR]

Abstract This study was carried out in order to investigate the toxicity on Lebanese soil and to show the impact of the anthropogenic activities, industrialization and urbanization, on the release of Polycyclic Aromatic Hydrocarbons (PAHs) in Lebanese soils. Hundred soil samples of different land use were screened for 17 PAHs using a UAE/GC-MS method. Detection frequency varied between 76 and 100% for most of the PAHs, where the ΣPAHs ranged from 33.5 to 4062.9 ng g−1. Moreover, BaPeq values varied between 0.93 and 332.4 ng g−1. BaPeq values in industrial and urban soils were 777 and 256 times higher than those in rural soil, respectively. None of the soil samples showed concentrations above the safe BaPeq value of 600 ng g−1. Significant decrease in concentration levels of ΣPAHs was obtained in the following order: Industrial, urban, traffic and agricultural. Furthermore, the relative high contribution of Chrysene, Benzo(a)Anthracene and Benzo(k)Fluoranthene in agricultural soils indicates that open burning remains an adopted way in Lebanon for disposal of agricultural residues, while the predominance of Benzo(ghi)Perylene and Benzo(b)Fluoranthene in industrial soils suggests the broad use of diesel powered engines in the Lebanese industrial sector. The ratios of Low Molecular Weight/High Molecular Weight and fluoranthene/fluoranthene+pyrene (Fln/Fln+Pyr) showed that PAHs in soil samples are mainly pyrogenic and created during combustion of petrol, coal, wood and other biomasses. Graphical abstract Image 1 Highlights • TEQ of PAHs was adopted to investigate anthropogenic impact on soil toxicity. • Industrial and urban TEQs were 777 and 256 times higher than rural TEQs. • PAHs levels decreased as follows: Industrial, urban, traffic and agricultural. • PAHs occurring in Lebanese soils were mainly of pyrogenic origins. [ABSTRACT FROM AUTHOR]

Methylparaben, which is known to be an endocrine-disrupting chemical, is added to various personal care products, including cosmetics, and is also used as a food preservative and in pharmaceuticals. However, information on the toxicity of methylparaben in soil ecosystems is limited. Furthermore, unlike other substances such as metals and pesticides, there is no regulation of levels or safe concentrations of methylparaben in soil ecosystems. Therefore, the aims of this study were to evaluate the toxicity of methylparaben on soil species and to derive hazardous concentration (HC) values with respect soil ecosystem protection. We conducted acute bioassays on eight species within six taxonomic groups and chronic bioassays on five species within four taxonomic groups. On the basis of the results obtained, we derived an acute HC 5 value of 44 mg/kg soil and a corresponding chronic value of 27 mg/kg soil for methylparaben using species sensitivity distribution methodology following Australian and New Zealand guidelines. Given that there has been no proposed standard value for methylparaben in soil in any country, it was not possible to compare the HC values calculated in this study with regulation standard levels. Nevertheless, to our knowledge, this study is first to assess the toxicity of methylparaben against soil-inhabiting species and to estimate acute and chronic HCs for soil fauna and flora. The results of this study will provide valuable fundamental data for the establishment of acceptable levels of methylparaben in soil. [ABSTRACT FROM AUTHOR]

In this study we used Pisum sativum as model plant, to perform a battery of plant biotests, based on the analysis of biological endpoints, ranging from the macroscopical to the microscopical level, in order to evaluate the toxicity of soils sampled from three different polluted areas (two industrial and one exposed to heavy vehicular traffic). In addition to the conventional germination tests and early root growth analyses, the mitotic index and the percentages of mitotic phases and of aberrations in the root apices were calculated. Moreover, DNA loss and damage were evaluated by flow cytometry and COMET assay, respectively. Root samples from polluted soils showed lower mitotic indices and a higher mitotic aberration percentage and DNA loss in comparison to the controls. Data obtained by COMET tests highlighted the soil genotoxicity, especially in the two industrial areas. All together, our results showed that the three studied sites were characterised by different levels of toxicity: in particular, one of the two industrial sites was the most harmful. [ABSTRACT FROM AUTHOR]

Variation in zinc toxicity with variation in environmental conditions was studied using the kinetic bioluminescence inhibition assay conducted with live cultures of Aliivibrio fischeri. A good correlation was observed between the static assay and flash assay for colorless non-turbid samples. Color and turbidity had negligible impact on the flash assay results while the static assay caused artifacts. Naturally occurring water samples showed wide variation in the toxicity profiles. Change in zinc toxicity was determined in response to variation in hardness, alkalinity and other coexisting cations/anions in model lake water and in the presence of a solid matrix. The presence of other anions and cations in model lake water reduced and enhanced zinc toxicity, respectively, due to changes in zinc speciation, and bioluminescence inhibition was well correlated with free zinc ion concentration. Increase in alkalinity and sulfate in model lake water lowered zinc toxicity, whereas increase in ammonium ions enhanced the toxicity. Variation in toxicity with hardness was dependent on the Ca: Mg hardness ratio in the samples. The presence of solid matrix decreased toxicity of the aqueous extracts, and toxicity of the matrix was found to increase with decreasing grain size. Speciation pattern of zinc in the respective fractions, however, revealed no direct relationship between zinc associated with fraction that are considered bioavailable to higher organism and the observed toxicity. This assay may be recommended for toxicity analysis of environmental samples since most of the results obtained correlate well with observations reported in toxicity studies with higher organisms. [ABSTRACT FROM AUTHOR]

Individual effects of nitrogen-based energetic materials (EMs) 2,4-dinitrotoluene (2,4-DNT), 2-amino-4,6-dinitrotoluene (2-ADNT), 4-amino-2,6-dinitrotoluene (4-ADNT), nitroglycerin (NG), and 2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (CL-20) on litter decomposition, an essential biologically-mediated soil process, were assessed using Orchard grass ( Dactylis glomerata ) straw in Sassafras sandy loam (SSL) soil, which has physicochemical characteristics that support “very high” qualitative relative bioavailability for organic chemicals. Batches of SSL soil were separately amended with individual EMs or acetone carrier control. To quantify the decomposition rates, one straw cluster was harvested from a set of randomly selected replicate containers from within each treatment, after 1, 2, 3, 4, 6, and 8 months of exposure. Results showed that soil amended with 2,4-DNT or NG inhibited litter decomposition rates based on the median effective concentration (EC50) values of 1122 mg/kg and 860 mg/kg, respectively. Exposure to 2-ADNT, 4-ADNT or CL-20 amended soil did not significantly affect litter decomposition in SSL soil at ≥ 10,000 mg/kg. These ecotoxicological data will be helpful in identifying concentrations of EMs in soil that present an acceptable ecological risk for biologically-mediated soil processes. [ABSTRACT FROM AUTHOR]

The aim of the current study was to identify major soil and leaf factors accounting for low natural rubber (NR, Hevea brasiliensis) productivity on tropical acid Acrisols in Vietnam. Twenty NR plots were measured with NR productivity, leaf factors (N, P, K, Ca, Mg, Mn, Cu, Fe, and Zn), soil factors (pH, particle size distribution, total C, N, P, K, exchangeable K, Ca, Mg, Al, Mn, Fe, Zn, available P). Cluster analysis showed that NR productivity could be separated into three clusters with low (23.2), medium (38.2), and high (61.3 g tree−1 harvest−1) yield. High-yield cluster had higher leaf P concentration and soil pH, while low-yield cluster had higher leaf Mn, soil exchangeable Al, and Mn concentration. Simple and multiple linear regression analysis applied with backward elimination procedure suggested that leaf and soil toxic concentration may be responsible for low NR productivity in the study soil. [ABSTRACT FROM AUTHOR]

Gas-to-liquid (GTL) products are synthetic hydrocarbons produced from natural gas using a catalytic process known as the Fischer-Tropsch process. This process yields a synthetic crude oil that consists of saturated hydrocarbons which can subsequently be refined to a range of products analogous to those obtained from petroleum refining. However, in contrast to their petroleum-derived analogs, GTL products are essentially free of unsaturated or aromatic compounds and do not contain any sulfur-, oxygen-, or nitrogen-containing compounds. Under new chemical substance notification requirements, an extensive testing program covering the entire portfolio of GTL products has been undertaken to assess their hazardous properties to human health and environment. The results of these studies have been summarized in a two-part review. Part 1 provides an overview of the mammalian toxicity hazardous properties of the various GTL products. This second part of the review focuses on the aquatic, sediment, terrestrial, and avian toxicity studies which assess the ecotoxicological hazard profile of the GTL products. Many challenges were encountered during these tests relating to dosing, analysis and interpretation of results. These are discussed with the intent to share experiences to help inform and shape future regulatory mandates for testing of poorly soluble complex substances. As was the case with the mammalian toxicology review, there were a few cases where adverse effects were found, but overall the GTL products were found to exert minimal adverse ecotoxicological effects and these were less severe than effects observed with their conventional, petroleum-derived analogs. [ABSTRACT FROM AUTHOR]

Constants for a Terrestrial Biotic Ligand Model (TBLM) to predict the Cu toxicity to barley root elongation (RE) were developed from controlled sand culture experiments. These constants were used to predict RE in soil culture. The competition of H + , Ca 2+ , and Mg 2+ to Cu 2+ toxicity were studied individually and independently, and linear relationships between EC50 free Cu 2+ and H + , Ca 2+ , and Mg 2+ activities were found, meaning that the cations H + , Ca 2+ , and Mg 2+ will alleviate the toxicity of Cu 2+ in solutions. Toxicity accompanying increasing concentration of solution ions other than Cu 2+ was observed and modeled as an osmotic effect which improved soil culture toxicity prediction. The Root Mean Square Error (RMSE) of %RE and EC50 (50% effective concentration) for soil toxicity prediction using TBLM parameters developed from sand culture are 13.0 and 0.23 respectively, which are as good as that of 14.0 and 0.24 using parameters that developed from soil culture itself. A model including the activity at the root plasma membrane surface was tested and found not to provide improvement over the use of bulk solution activity to predict metal toxicity. TBLM parameters obtained from water solution culture were unable to accurately predict the EC50s in soils whereas the parameters obtained from sand culture were able to predict the toxicity in soils. Including the toxicity of CuOH + was found to improve the toxicity prediction slightly. [ABSTRACT FROM AUTHOR]

Soil contamination caused by persistent organic pollutants (POPs) has been a worldwide concern for decades. With lindane-contaminated soil as the target, a mechanochemical method assisted by CaO was comprehensively evaluated in terms of its remediation performance, degradation mechanism and overall assessment. The mechanochemical degradation performance of lindane in cinnamon soil or kaolin was determined under different additives, lindane concentrations and milling conditions. 2,2-Diphenyl-1-(2,4,6-trinitrophenyl) hydrazinyl free radical (DPPH•) and electron spin resonance (ESR) tests evidenced that the degradation of lindane in soil was caused mainly by the mechanical activation of CaO to produce free electrons (e-) and the alkalinity of the generated Ca(OH) 2. Dehydrochlorination or dechlorination by elimination, alkaline hydrolysis, hydrogenolysis and the subsequent carbonization were the main degradation pathways of lindane in soil. The main final products included monochlorobenzene, carbon substances and methane. The mechanochemical method with CaO was proved to also efficiently degrade lindane in three other soils and other hexachlorocyclohexane isomers and POPs in soil. The soil properties and soil toxicity after remediation were assessed. This work presents a relatively clear discussion of various aspects of the mechanochemical remediation of lindane-contaminated soil assisted by CaO. [Display omitted] • CaO assisted mechanochemical degradation mechanism of lindane in soil was elucidated. • Mechanochemical method with CaO is applicable to different HCHs, POPs and soils. • The changes of soil properties after mechanochemical treatment were characterized. • The soil toxicity was evaluated comprehensively after mechanochemical remediation. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Topsoil contamination and toxicity was evaluated in a petrochemical area in Sicily. • Inorganic and organic pollutant levels were measured at different distances from refineries. • Multiple bioassays were carried out in testing topsoil toxicity. • Consistent results were found in topsoil from urban areas vs. sampling sites. [ABSTRACT FROM AUTHOR]

We investigated individual toxicities of the nitrogen-based energetic materials (EMs) 2,4-dinitrotoluene (2,4-DNT); 2-amino-4,6-dinitrotoluene (2-ADNT); 4-amino-2,6-dinitrotoluene (4-ADNT); and nitroglycerin (NG) on microbial activity in Sassafras sandy loam (SSL) soil, which has physicochemical characteristics that support very high qualitative relative bioavailability for organic chemicals. Batches of SSL soil for basal respiration (BR) and substrate-induced respiration (SIR) assays were separately amended with individual EMs or acetone carrier control. Total microbial biomass carbon (biomass C) was determined from CO2 production increases after addition of 2500 mg/kg of glucose-water slurry to the soil. Exposure concentrations of each EM in soil were determined using US Environmental Protection Agency method 8330A. Basal respiration was the most sensitive endpoint for assessing the effects of nitroaromatic EMs on microbial activity in SSL, whereas SIR and biomass C were more sensitive endpoints for assessing the effects of NG in soil. The orders of toxicity (from greatest to least) were 4-ADNT > 2,4-DNT = 2-ADNT > NG for BR; but for SIR and biomass C, the order of toxicity was NG > 2,4-DNT > 2-ADNT = 4-ADNT. No inhibition of SIR was found up to and including the greatest concentration of each ADNT tested in SSL. These ecotoxicological data will be helpful in identifying concentrations of contaminant EMs in soil that present acceptable ecological risks for biologically mediated processes in soil. Environ Toxicol Chem 2017;36:2981-2990. Published 2017 Wiley Periodicals Inc. on behalf of SETAC.This article is a US government work and, as such, is in the public domain in the United States of America. [ABSTRACT FROM AUTHOR]

Toxicity and persistence of heavy metals, which are accumulated in the environment as the result of diverse industrial activities, represent serious environmental problem worldwide. The intense mineral extraction in mining areas has produced a large amount of waste material and tailings, which release toxic elements to the environment. The aim of the study was to determine in two time horizons (1997, 2015) the heavy metal contents of samples derived from ten sampling sites located in the former mining area of Central Spiš (Slovakia). In order to compare the level of contamination, the contamination factor (Cif), degree of contamination (Cd), and pollution load index (PLI) were computed. Spearman's correlation coefficient was used in order to detect the relationships among heavy metals. A serious situation was found for Hg, Zn, and Cd, which exceeded limit values at all sampling sites within both studied years. In 1997, the average values of contamination factor have shown very high contamination with all studied heavy metals, and moderate contamination with Co. In 2015, the study area was classified as very highly contaminated with As, Hg, Zn, Cu, considerably contaminated with Ni, Cr, Pb, and Cd, while Co contamination was not detected. Since 1997 till 2015 the pollution load index decreased by about 38%, nevertheless even then almost all sampling sites were classified as heavily polluted. Despite the fact that mining activities were stopped or limited at the beginning of the 21st century, the presence of heavy metals in soils remains at a serious level. The high level of contamination is a result of heavy metal persistence and non-biodegradability. [ABSTRACT FROM AUTHOR]

Large amounts of residues generated by agricultural, urban and industrial activities are dumped daily on the soil. This practice deserves special attention because it causes serious environmental problems. This study evaluated the toxic potential of the sugarcane vinasse, a by-product of the sugar-alcohol industry, and the biosolid, a residue produced by wastewater treatment plants, both widely used as fertilizers. The evaluation was performed through bioassays using a typical soil bioindicator, the diplopod Rhinocricus padbergi. The specimens were exposed to soils containing these residues in concentrations that are compatible with the Brazilian regulation for agricultural use. Semi-quantitative immunolabelling analyses of the stress protein HSP70 were performed on the midgut of the studied diplopods. There was a significant increase in the immunolabelling of HSP70 proteins as a response to xenobiotics from both residues, particularly in regions where the function of the cells is the detoxification of the organ (e.g. the hepatic cell layer and specific regions of the epithelium). Higher immunolabelling was observed in the specimens exposed to vinasse in comparison with the biosolid exposure. This demonstrates that the substances in the tested residues had proteotoxic action in the exposed animals and induced a cytoprotective response, which led to higher stress protein immunolabelling. Therefore, caution is needed for the use of such residues in agriculture. [ABSTRACT FROM AUTHOR]

Purpose: Soils formed in metallic mines and serpentinite quarries, among other unfavourable features, have high levels of heavy metals. They can release into the environment causing surface and subsurface water contamination, uptake by plants, their accumulation in the food chain and adverse effects on living organisms. In this work, we studied the magnitude of the soils' toxic effects not only on spontaneous plants but also on two species with phytoremediation potential. Materials and methods: Several soils from two different exploitations were selected: a lead and zinc mine and a serpentinite quarry. Soils were characterized, and the pseudo-total and extractable contents of Co, Cr and Ni in soils from a serpentinite quarry were determined. The Cd, Pb and Zn pseudo-total and extractable contents were determined in soils developed in the Pb/Zn abandoned mine. Using a biotest, the chronic toxicity of the soil samples on higher plants was determined. Festuca ovina L., Cytisus scoparius (L.) Link., Sinapis alba L. and Brassica juncea L. were selected, the first two because they are spontaneous plants in the study areas and the last two because they have heavy metal phytoremediation potential. Results and discussion: Pseudo-total contents of Co, Cr and Ni in the serpentinite quarry soils and of Zn, Pb and Cd in the Zn/Pb mine soils exceed generic reference levels. CaCl is the reactant that extracts the highest proportion of Co, Cr and Ni in the quarry soils and EDTA the largest proportion of Pb Zn and Cd content in the mine soils. The germination index values based on seed germination and root elongation bioassays revealed increasing plant sensitivity to the mine soils in the following order: B. juncea < S. alba < F. ovina < C. scoparius. The wide range of GI values indicates that the response of test plants to soil heavy metals depended on their concentrations and soil characteristics, especially pH and organic matter content. Conclusions: The pollution index indicates severe Cd, Pb and Zn contamination in the mine soils, as well as high Cr and Ni and moderate Co contamination in the serpentinite quarry soils. The performed biotests were suitable for identifying toxic soils and showed that the studied soils are toxic to the spontaneous plants, more to C. scoparius than to F. ovina. They also indicate that the mine soils are more toxic than the quarry soils for both species. [ABSTRACT FROM AUTHOR]

The use of fluoride based foams increases the effectiveness of fire-fighting operations, but they are also accompanied by major drawbacks regarding environmental safety of perfluorinated compounds (PFCs). The main concern with PFCs release is due to their well-known persistence and bioaccumulative potential, as they have been detected in many environmental samples. There is a significant knowledge gap on PFC toxicity to plants, even though such data could be useful towards bioremediation procedures. It is consensus that a realistic assessment of fire-fighting foam toxicity should cover as many test organisms as possible, however, few studies combine the performance of ecotoxicological tests with a detailed study of microbial communities in soil contaminated with firefighting foams. Our research evaluated the effects of natural attenuation of PFCs on the development of arugula and lettuce seeds. The effects of variable PFCs amounts were also observed in soil microbiota using the 2,6 dichlorophenol-indophenol redox dye as microbial metabolism indicator. We aimed to determine whether aqueous film forming foams toxicity increased or decreased over time in a simulated contamination scenario. We argued that the long-term biotransformation of fire-fighting foams should be taken in to account when evaluating toxicity, focusing on a time-based monitoring analysis, since potentially toxic intermediates may be formed though biodegradation. The phyto-toxicity of PFCs to lettuce and arugula was high, increasing as a function of the concentration and decreasing as a function of exposure time to the environment. However, very specific concentrations throughout biodegradation result in the formation of non-inhibiting intermediates. Therefore, variable biodegradation-dependent germination rates may be misleading on non-time-based monitoring approaches. Also, the low phyto-toxicity after 240 days does not exclude the potential for PFC bioaccumulation in plants. We also proposed that the colorimetric data modelling could also establish a novel toxicity parameter to evaluate the release impacts to soil and biota. The combined assays allowed the monitoring of PFCs during long-term exposition to plants as well as their immediate effects on the same soil microbiota. [ABSTRACT FROM AUTHOR]

Colonial-nesting organisms can strongly alter the chemical and biotic conditions around their aggregation sites, with cascading impacts on other components of the ecosystem. In tropical Australia, Metallic Starlings ( Aplonis metallica) nest in large colonies far above the forest canopy, in emergent trees. The ground beneath those trees is open, in stark contrast to the dense foliage all around. We surveyed the areas beneath 27 colony trees (and nearby randomly chosen trees lacking bird colonies) to quantify the birds' impacts on soil and vegetation characteristics, and to test alternative hypotheses about the proximate mechanisms responsible for the lack of live vegetation beneath colony trees. Nutrient levels were greatly elevated beneath colony trees (especially, those with larger colonies), potentially reaching levels toxic to older trees. However, seedlings thrived in the soil from beneath colony trees. The primary mechanism generating open areas beneath colony trees is disturbance by scavengers (feral pigs and native Turkeys) that are attracted in vast numbers to these nutrient hotspots. Seedlings flourished within exclosures inaccessible to vertebrate herbivores, but were rapidly consumed if unprotected. Our results contrast with previous studies of colonies of seabirds on remote islands, where a lack of large terrestrial herbivores results in bird colonies encouraging rather than eliminating vegetation in areas close to the nesting site. In our continental study system, scavengers may rapidly dilute the spatial heterogeneity generated by the massive nutrient subsidy from bird colonies. [ABSTRACT FROM AUTHOR]

A direct contact bioassay of thiosulfate utilizing denitrifying bacteria (TUDB) based on inhibition of gas production was deployed to assess the toxicity of naturally contaminated field soils and soils artificially contaminated with heavy metals. Test procedure producing optimal conditions responsible for maximum gas production was 0.5 mL test culture, 1 g soil sample, 80 RPM, and 48 h reaction time. Similarly, the concentrations which generated a 50% reduction in gas production by TUDB for the tested heavy metals were 3.01 mg/kg Cr6+; 15.30 mg/kg Ni2+;15.50 mg/kg Cu2+;16.60 mg/kg Ag+; 20.60 mg/kg As3+; 32.80 mg/kg Hg2+; 54.70 mg/kg Cd2+; and 74.0 mg/kg Pb2+. Because soil toxicity is usually influenced by various physicochemical characteristics, ten reference soils were used to determine the toxicity threshold for evaluating the toxicity of naturally contaminated field soils. All eight contaminated soils were toxic to the TUDB bioassay because their levels of inhibition ranged between 72% and 100% and exceeded the determined toxicity threshold of 10%. Compared to other direct contact assays, the newly developed assay TUDB proved to be very robust, producing highly sensitive data while the different soil physicochemical properties exerted minimal influence on the gas production activity of TUDB. Additionally, the simplicity of the developed methodology coupled with the elimination of pretreatment procedures such as elutriation, and ability to perform generate sensitive data in turbid and highly colored samples makes it, cost-effective, and easily adaptable for the assessment of heavy metal and field contaminated soils when compared with other conventional assays which require sophisticated instrumentation and prolonged testing procedures and times. • TUDB was deployed as a direct contact microbial bioassay for soil toxicity assessments. • Increasing concentration of heavy metal contaminants adversely affected the gas production by TUDB. • Soil toxicity by Cr6+, Ni2+, Cu2+, and Ag+ was more toxic to TUDB than by Hg2+, Pb2+ and Cd2+. • Soil properties had minimal interference on gas production by TUDB. • Application of the determined toxicity threshold for the evaluation of the toxicity of field contaminated soils. [ABSTRACT FROM AUTHOR]