Unpolluted Soil Research Articles

Soil Enzyme Responses and Crop Productivity Indices Assessment in Agricultural Soil Impacted with Heavy Metals

The present study assessed the productivity of cultivated garden vegetable among other ecological assessments in soil samples impacted with heavy metals. Assay of soil enzyme responses showed the activity of: catalase, peroxidase, lipase and ureasewith corresponding OD reading of 0.750, 2.05, 0.22 and 1.704 respectively. There were noticeable increases in the activity of ureaseandperoxidasewhilecatalaseandlipaseactivitywererelativelylowinthesampledsoil. Out of the 321g of the vegetable seedstested for viability, 45% representing 144.45g was used for the planting and further experiment. After three days of cultivation, germination process was recorded faster in the <i>T. oleifera </i>potted ridge while <i>Amaranthus </i>and <i>Solanum </i>sp seed took 3-4 day for break full dormancy. Determination of total chlorophyll a and b in the selected vegetables showed a correlative increase in chlorophyll a and b in soils contaminated with Zn, Cu and Fe in all the cultivated vegetables: T<i>. oleifera</i>, <i>Amaranthus </i>and <i>Solanum </i>sp, respectively. There are significant increase in total cholorphyl a (0.9mg/g) and b (0.8mg/g) contents from the results when compared with the control experiment as other soil contaminated with heavy metals such as: Pb, and As repressed the selected vegetables cultivated in the soil samples. However total chlorophyll a was seems lightly higher than cholophyl b in all the selected vegetable cultivated in soil. Analysis on the impact of heavy metals on the shootlength of the cultivated vegetables analysed for thirty-one days showed regressive increase in the shootlength of the cultivated vegetables as the period of harvest increases from 0-31 when compared with the control experiment. However Cd and As had the most estimated impact on the vegetables in all the cultivated soils and its impact progresses as the period of harvest increases. Dry matter weight contents of the cultivated vegetables cultivated in the polluted soils were analysed; also the same index was assessed in the vegetables from the unpolluted soils. There was a significant increase in the dry matter contents of the cultivated vegetables in soil polluted with Cu, Fe and Zn respectively. However, dry matter contents were seen progressively low in vegetables cultivated in soils polluted with Cd, As and Pb. When compared with the control experiment. The results from the present study have shown the vulnerability of agricultural soil and cultivated vegetables to effluent from industrial bias sources used for irrigation and its impact on agricultural productivity.

Quantitative analysis of soil quality around brick kilns using pollution indices and ANOVA in Jammu district of Jammu and Kashmir, India

The study investigated soil quality around brick kilns in the Jammu district of Jammu and Kashmir, analyzing 200 samples from 50 sites for selected parameters such as pH, electrical conductiv1ity, soil temperature, organic carbon content, organic matter, macronutrients, and heavy metals. The findings revealed that soil electrical conductivity ranged from 0.33 to 0.63 dS/m, with significant differences observed at varying distances from the kilns. Copper concentrations were highest at 5.32 mg/kg near the kilns, while iron and lead levels also varied significantly, indicating potential contamination. The mean soil temperature was recorded to be 27.69°C.The pH values ranged from 6.5 to 7.8, and the average pH of 8.22 indicated the slightly alkaline nature of the soil around the brick kilns. The organic carbon ranged from 0.34% to 1.02%.Soil temperature and electrical conductivity decreased with increasing distance from the kilns, with temperature showing positive correlations with organic carbon, organic matter, nitrogen, potassium, manganese, and iron and negative correlations with pH, phosphorus, zinc, copper, lead, and cadmium. A perfect positive correlation was noted among nitrogen, organic carbon, and organic matter. Heavy metals, except for zinc and manganese, showed positive correlations with each other. The average Zn, Cu, Mn, Fe, Pb and Cd concentration was recorded as 1.07, 1.03, 6.71, 10.30, 37.04 and 1.91 ppm, respectively. The contamination factor indicated moderate contamination with lead and cadmium, while the geo-accumulation index also suggested moderate contamination. The pollution load index reflected unpolluted soil and enrichment factor values for heavy metals ranked as Cd > Pb > Cu > Zn > Mn > Fe.ANOVA results revealed significant variations in electrical conductivity, copper, iron, and lead, underscoring the potential environmental impacts at different distances from the kilns. However, no significant differences were found between agricultural and non-agricultural sites in other physicochemical parameters. These variations highlight the considerable impact of brick kilns on soil health, emphasizing the need for enhanced environmental management and further research to mitigate these effects.

Assembly patterns and key taxa of bacterial communities in the rhizosphere soil of moso bamboo (Phyllostachys pubescens) under different Cd and Pb pollution

Moso bamboo is excellent candidate for cadmium (Cd)/lead (Pb) phytoremediation, while rhizosphere microbiome has significant impact on phytoremediation efficiency of host plant. However, little is known about the rhizosphere bacterial communities of moso bamboo in Cd/Pb contaminated soils. Therefore, this study investigated the assembly patterns and key taxa of rhizosphere bacterial communities of moso bamboo in Cd/Pb polluted and unpolluted soils, by field sampling, chemical analysis, and 16S rRNA gene sequencing. The results indicated α-diversity between Cd/Pb polluted and unpolluted soils showed a similar pattern (p > 0.05), while β-diversity was significantly different (p < 0.05). The relative abundance analysis indicated α-proteobacteria (37%) and actinobacteria (31%) were dominant in Cd/Pb polluted soils, while γ-proteobacteria (40%) and α-proteobacteria (22%) were dominant in unpolluted soils. Co-occurrence network analysis indicated microbial networks were less complex and more negative in polluted soils than in unpolluted soils. Mantel analysis indicated soil available phosphorus, organic matter, and available Pb were the most important environmental factors affecting microbial community structure. Correlation analysis showed 11 bacterial genera were significantly positively related to Cd/Pb. Overall, this study identified the bacterial community composition of bamboo rhizosphere in responding to Cd/Pb contamination and provides a theoretical basis for microbe-assistant phytoremediation in the future.

The effectiveness of various biochar types in enhancing the phytoremediation of soils polluted with petroleum hydrocarbon

AbstractBackgroundBiochar can enhance phytoremediation in petroleum hydrocarbon polluted soils, making it an intriguing soil amendment option for remediating polluted soil. Biochar can improve the fertility of depleted soils through a range of mechanisms. This study can contribute valuable insights into the origin of biochar and enhance our understanding of the efficacy of different biochar types in remediating petroleum hydrocarbon polluted soils.AimsTo assess the efficacy of different biochar types and plant growth in remediating petroleum hydrocarbon polluted soils.MethodsA field experiment was conducted at the automobile workshop (commonly called mechanic village) from July to October 2021, using a randomized complete block design. The land was sectioned into designated plots with three replicates. Maize stalk biochar (MSB) and nipa palm biochar (NPB) were treated differently in each plot at a rate of 20 t ha−1. Plots containing no biochar were used as controls. Initial and final soil analyses were conducted.ResultsPreliminary soil assessments revealed higher values of soil bulk density (1.51 g cm−3), moisture content (35.02%), organic carbon (41.01 g kg−1), cation exchange capacity (13.27 cmol kg−1), total petroleum hydrocarbon content (PHCt) (775.83 mg kg−1), cadmium (Cd) (5.41 mg kg−1), chromium (Cr) (25 mg kg−1), lead (Pb) (33.51 mg kg−1), and zinc (Zn) (0.91 mg kg−1) in the polluted soil than in the unpolluted counterpart. The polluted soil displayed lower hydraulic conductivity (Ks) (1.17 cm h−1), available phosphorus (69.46 mg kg−1), manganese (Mn) (6.38 mg kg−1) and iron (Fe) (4.18 mg kg−1) contents than the unpolluted soil. The PHCt, Cd, and Cr were significantly decreased following the application of biochar. NPB recorded the lowest petroleum hydrocarbon (19%), lead (37%), manganese (57%), and zinc (69%) contents, whereas MSB had the lowest cadmium (50%) and chromium (27%) contents when compared with the control. Between heavy metal accumulations in the leaves and fruits, a greater accumulation of Cd, Cr, and Pb was found in the leaves, whereas Ni accumulation was found in the fruits. The highest Cd (47.0 mg kg−1) and Ni (8.3 mg kg−1) accumulations in the leaves were recorded in NPB treated plots. Similarly, Cd (5.3 mg kg−1), Cr (3.7 mg kg−1), Pb (21.6 mg kg−1), and Ni (23.4 mg kg−1) accumulation in the fruits recorded the highest values in the NPB treated plots. The NPB plants were the tallest compared with the other treatments. In addition, NPB plants had the widest leaf area compared with other treatments.ConclusionThe results indicated that the amendment of NPB may be suitable for the phytoremediation of soils polluted with petroleum hydrocarbons.

Spatial variability of heavy metals concentrations in soil of auto-mechanic workshop clusters in Nsukka, Nigeria

The indiscriminate disposal of spent engine oils and other hazardous waste at auto mechanic workshops clusters in Nsukka, Enugu State, Nigeria is an environmental concern. This study examines the concentration of heavy metals in the soil inside the workshop cluster and in the unpolluted soil outside the workshop cluster at approximately 100 m. Ten sampling points were randomly selected from within the cluster and another ten from outside the cluster. Using a hand-held Global Positioning System, the coordinates of the selected points were established and used to create a digital map. Soil samples at depths of 0–30 cm and 30–60 cm, were analyzed for Cu, Fe, Zn, Pb, As and Cd using Spectrophotometer. Moisture content determination and particle size analysis were also done on the samples. Spatial variability of heavy metals concentrations of the studied site was also mapped with ArcGIS 10.2.2 using interpolation methods. Results showed that the soil ranged from sandy loam to sandy clay loam. Cadmium and Zinc had the lowest and highest concentration, respectively, in the studied area. Comparing the concentrations of heavy metals in soils within and outside the auto mechanic cluster revealed notable differences across various depths (0–30 cm and 30–60 cm). The analysis results for soil samples within the cluster exhibited concentration levels (mg/kg) ranging from 0.716–0.751 (Cu), 2.981–3.327 (Fe), 23.464–30.113 (Zn), 1.115–1.21 (Pb), 2.6–2.912 (As), and 0.133–0.365 (Cd) demonstrating a variation pattern in the order of Zn > Fe > As > Pb > Cu > Cd. Conversely, for soil samples outside the cluster, concentration levels (mg/kg) ranged from 0.611–0.618 (Cu), 2.233–2.516 (Fe), 12.841–15.736 (Zn), 0.887–0.903 (Pb), 1.669–1.911 (As), and 0.091–0.091 (Cd). To assess the disparity in heavy metal concentration levels between samples collected within and outside the clusters, ANOVA test was performed. The test showed significant difference in heavy metal concentrations between samples within and outside the auto mechanic cluster (p < 0.05), implying auto mechanic activities significantly impact heavy metal levels within the cluster compared to outside areas. The assessment of soil pollution utilized indices including the Geo-accumulation Index (Igeo), Contamination factor (Cf), and anthropogenic metal concentration (QoC). Zinc, Cadmium, and Arsenic showed the highest contamination factors, indicating significant soil contamination likely due to anthropogenic activities. The concentrations of the metals analyzed were within WHO permissible limits while the metals concentrations were also observed to decrease as depth was increased. Using ArcGIS 10.2.2, spatial maps showing heavy metal distribution were developed, with the Kriging method proving superior. This study suggests that heavy metal levels in the soil at the area be monitored on a regular basis.

Evaluation of Heavy Metals in Roadside Soil of Tumfure Main Market, Gombe State

Heavy metal pollution has been a problem of concern in soil ecology in recent decades. This study evaluated the physico-chemical characteristics and heavy metal contents in roadside soil samples of Tumfure main market, Gombe, Nigeria. The soil samples were collected from six different sampling points with a control sample each by handpicking, this was followed by oven-drying, ground to fine grain, and then sieved using a 2 mm mesh sieve. The pH, electrical conductivity and bulk density were carried out on the soil samples, sieve and sedimentation method were used to determine the soil texture. The soil samples were weighed and digested using mixture of HCl and HNO3. The contents (mg/kg) of four metals (cadmium, copper, lead and zinc) were estimated using Atomic Absorption Spectrophotometer (AAS). Among the metals analyzed, the contents of Cd, Cu and Pb were not detected while the content of Zn (23.454 - 36.026) was found to be within the desirable permissible limits by the World Health Organization (WHO) and European Regulatory Standards (EURS) whose prevalence is to be considered non-toxic in unpolluted soils.

Cadmium/zinc stresses and plant cultivation influenced soil microflora: a pot experiment conducted in field

It’s of great challenge to address for heavy metal-contaminated soil. Once the farmland is contaminated with heavy metals, the microbial ecology of the plant rhizosphere will change, which in turn impacts crop productivity and quality. However, few studies have explored the effects of heavy metals on plant rhizosphere microbes in farmland and the role that plant cultivation plays in such a phytoremediation practice. In this study, the impacts of comfrey (Symphytum officinale L.) cultivation and the stresses of cadmium/zinc (Cd/Zn) on rhizosphere soil microflora were examined. Microbial DNA was collected from soils to evaluate the prevalence of bacteria and fungi communities in rhizosphere soils. High-throughput 16 S rRNA sequencing was used to determine the diversity of the bacterial and fungal communities. The results showed that growing comfrey on polluted soils reduced the levels of Cd and Zn from the vertical profile. Both the comfrey growth and Cd/Zn stresses affected the community of rhizosphere microorganisms (bacteria or fungi). Additionally, the analysis of PCoA and NMDS indicated that the cultivation of comfrey significantly changed the bacterial composition and structure of unpolluted soil. Comfrey cultivation in polluted and unpolluted soils did not result in much variance in the fungi’s species composition, but the fungal compositions of the two-type soils were noticeably different. This work provided a better understanding of the impacts of Cd/Zn stresses and comfrey cultivation on rhizosphere microbial community, as well as new insight into phytoremediation of heavy metal-contaminated soils.

Characterization and identification of long-chain hydrocarbon-degrading bacterial communities in long-term chronically polluted soil in Ogoniland: an integrated approach using culture-dependent and independent methods

Escalating oil consumption has resulted in an increase in accidental spills of petroleum hydrocarbons, causing severe environmental degradation, notably in vulnerable regions like the Niger Delta. Complex mixture of these hydrocarbons particularly long-chain alkanes presents unique challenges in restoration of polluted environment due to their chemical properties. This study aimed to investigate the long-chain hydrocarbon-degrading bacterial communities within long-term chronically polluted soil in Ogoniland, by utilizing both traditional cultivation methods and modern culture-independent techniques. Results revealed that surface-polluted soil (SPS) and subsurface soil (SPSS) exhibit significantly higher total organic carbon (TOC) ranging from 5.64 to 5.06% and total petroleum hydrocarbons (TPH) levels ranging from 36,775 ppm to 14,087 ppm, compared to unpolluted soil (UPS) with 1.97% TOC and 479 ppm TPH, respectively. Analysis of carbon chain lengths reveals the prevalence of longer-chain alkanes (C20-28) in the surface soil. Culture-dependent methods, utilizing crude oil enrichment (COE) and paraffin wax enrichment (PWE), yield 47 bacterial isolates subjected to a long-chain alkane degradation assay. Twelve bacterial strains demonstrate significant degradation abilities across all enriched media. Three bacterial members, namely Pseudomonas sp. (almA), Marinomonas sp. (almA), and Alteromonas (ladA), exhibit genes responsible for long-chain alkane degradation, demonstrating efficiency between 50 and 80%. Culture-independent analysis reveals that surface SPS samples exhibit greater species richness and diversity compared to subsurface SPSS samples. Proteobacteria dominates as the phylum in both soil sample types, ranging from 22.23 to 82.61%, with Firmicutes (0.2–2.22%), Actinobacteria (0.4–3.02%), and Acidobacteria (0.1–3.53%) also prevalent. Bacterial profiles at genus level revealed that distinct variations among bacterial populations between SPS and SPSS samples comprising number of hydrocarbon degraders and the functional predictions also highlight the presence of potential catabolic genes (nahAa, adh2, and cpnA) in the polluted soil. However, culture-dependent analysis only captured a few of the dominant members found in culture-independent analysis, implying that more specialized media or environments are needed to isolate more bacterial members. The findings from this study contribute valuable information to ecological and biotechnological aspects, aiding in the development of more effective bioremediation applications for restoring oil-contaminated environments.

Effect of Crude Oil Polluted Soil on the Reproductive Growth of Plantain (Musa paradisiaca L.)

Soil polluted by crude oil is detrimental to the survival of plants and microbes. Plantain (Musa paradisiaca L.) is a major important food crop, showing tolerance to abiotic and biotic stress. This study investigated the impact of soil polluted with Bonny Light crude oil (BLCO) on the reproductive growth of two plantain cultivars. Crude oil was added to agricultural soil on which plantain suckers were planted. Reproductive growth was then periodically assessed. The number of suckers was significantly higher in French plantain plants grown on polluted soil in comparison with control. False Horn plantain plants on unpolluted soil produced more suckers in comparison to the plants on polluted soil. Also, the time between planting to flower bud appearance and flower bud appearance to bud opening reduced in plants on polluted soil in both cultivars in comparison with the control. Statistically, there was an insignificant decrease in the fruit size of False Horn plantain on polluted soil compared with the control while there was an appreciable increase with a significant effect in fruits size of French plantain on polluted soil compared with the control. Generally, French plantain tolerated the stress induced by crude oil pollution of soil in its reproductive growth more than False Horn. The reproductive growth of False Horn and French plantain cultivars show that there could be varied response to crude oil polluted soil.

Phytoremediation capacity of hybrid aspen at sites affected by industry and agriculture.

Fast-growing Populus spp. are well-acknowledged to restore contaminated soils from heavy metals in industrial areas. Thus far, there is no knowledge about the phytoremediation capacity of Populus spp. plantations in hemiboreal Estonia conditions to restore industrially polluted areas. The objective of this study was to assess the soil contamination rate of heavy metals (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) and their uptake by mature hybrid aspen (Populus tremula × Populus tremuloides Michx.) in plantations in different industrial pollution areas (e.g. cement factory, oil shale mining). For the reference, industrially polluted plantations were compared with the low pollution area hybrid aspen plantation on former agricultural soil, which was influenced by fertilization and liming before afforestation. Twenty-one years after afforestation, soil samples were collected from the 0-10cm topsoil layer. Aboveground biomass sampling was performed for bark and stem wood by ingrowth cores to separate wood formed during early (1-10years) and late (11-21years) stand development. Two decades after the afforestation of industrially polluted areas, the heavy metal concentrations in the soil were higher than the reference plantation and the standard reference for unpolluted soils in most cases. The highest concentrations of heavy metals in woody biomass were in the oil shale quarry spoil; because of poor growth, the accumulated pools in aboveground biomass were low. Cd differed from other metals and accumulated less in wood and more in bark. The concentration of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni and Zn) was higher in the first decade of stand formation (1-10years) than in the last 10years (11-21years). High pools of heavy metals were accumulated in aboveground biomass in the reference plantation, indicating the considerable removal of heavy metal residues from the previous fertilization and liming source with harvest. Two decades of afforestation with hybrid aspen is too short for complete ecosystem restoration from heavy metals in industrially polluted areas.

Microbial Populations of Agricultural Soil Polluted With Crude Oil

Crude oil pollution of the soil has become a public health and environmental concern. It impacts soil microbial diversity and population. In this study, the microbial population of crude oil polluted soil and unpolluted were determined. The potential for the indigenous organisms to utilize hydrocarbon as a source of carbon was also determined. A soil sample was obtained from an agricultural field and polluted with a defined amount of crude oil for 12 weeks. The microbial population in the polluted soil and unpolluted soil were estimated and characterized following standard microbiological methods. The heterotrophic bacterial and fungal counts in the unpolluted and polluted soil were 6.5 x 104CFU/g and 4.7 x 104 CFU/g, and 6.3 x104 CFU/g and 3.5 x104 CFU/g respectively. Total hydrocarbon utilizing bacterial and fungal counts in the polluted soil was 4.6 x 104 CFU/g and 2.8 x 104 CFU/g. The genera of bacteria and fungi identified in the soil samples were Bacillus, Enterococcus, Micrococcus, Escherichia, Pseudomonas, Staphylococcus, Serratia, Proteus, Klebsiella, Arthrobacter, Aspergillus, Candida, Penicillium, Fusarium, Trichoderma, Cladosporium and Hyphopichia. The preliminary screening for hydrocarbon utilization shows that Bacillus cereus, Bacillus subtilis, Aspergillus niger and Hypopichia burtonii were excellent hydrocarbon utilizers and can be used in bioaugmentation.

ASSESSMENT OF THE POTENTIALLY TOXIC ELEMENTS CONTAMINATION AND THEIR UPTAKE BY AMBROSIA ARTEMISIIFOLIA L. IN SOILS IN THE NORTHERN PART OF BOSNIA AND HERZEGOVINA

This research focused on the determination of potentially toxic elements (PTEs) distribution in different agricultural soils and Ambrosia atremisiifolia L. (ragweed) at seven, different locations in the northern part of Bosnia and Herzegovina (BiH). Quantification of PTEs was done using atomic absorption spectrophotometry provided after acid digestion of the air-dried samples of soil and plant material. Determined content of elements in the soils increased as follows: Cd&lt;Pb&lt;Cu&lt;Zn&lt;Cr&lt;Ni&lt;Mn&lt;Fe and were under the allowed maximum for unpolluted soils, except for Ni and Cr. However, transfer of Ni and Cr from the soil to the ragweed as well as their bioaccumulation was not intensive. Established metal contents ratio from plant tissues (root and shoot) to soil for both elements, represented their bioaccumulation factors (BAF), which were extremely low in the roots, as well as in the shoots, both in average less than 0.2. On the other hand, Zn showed a tendency to accumulate in ragweed shoots (BAF=2.07). The study showed that uptake and accumulation of PTEs in the ragweed was mainly influenced by their content in the soil, as well as specific characteristics and biological role of each element. Hence, content of PTEs in the ragweed tissue could be used as the soil contamination degree indicator.

Assessment of Some Trace Elements in Surface Water and Soil near Al-Ahdab Oil Field, Wasit Governorate, Iraq

The main objective of this munscript is to spot light on the negative consequences of oil emissions from Al-Ahdab oil field on the water and soil surrounding the oil field at Wasit Governorate. To obtain this objective, seven sediment samples were collected from the surfacre soil, in addition to five water samples from the Tigris River near Al-Ahdab oil field within Al-Kut Wasit governorate. The more effective eight trace elements were chosen to detect the limitations of their occurrence in the soil and water of the study area, these are Fe, Cd, Cu, Cr, Ni, Pb, Zn, and Zr. The Zr is used as a background for the specific equations applied. Samples of sediments and water were collected in October 2022. The standardization of the Enrichment Factor (EF), geo-accumulation index (I-geo), and contamination factor (CF) in addition to the pollution load index (PLI) were applied to detect the extent of soil pollution. In contrast, the hydrochemistry of water samples was determined by comparing the results of the analysis with the standards of WHO, 2018, and IQS, 2009. The enrichment factor value (EF) Cadmium value (Cd) in soil samples is 6.6, which reflects a significant impact of air emissions, the cobalt (Co) value is 1.77m this value reflects minimum Enrichment factor while the EF has a rather moderate enrichment factor. By applying the I-geo equation, the oitput results indicate unpolluted soil for Co, and Ni metals, while it is moderately polluted for Cu, Cr, Zn, and Pb metals. According to the PLI index, the soil of the study area is ordered as moderately contaminated for these metals. As for the hydrochemistry of surface water of the Tigris River near the study area, the water samples are classified as not contaminated by (Ni, Cd, Pb, Zn, Cr, and Cu).

Crude oil pollution effect on agricultural soil properties and germination of bean (&lt;i&gt;Vigna unguiculata(/i) L.) seed

Crude oil pollution affects not only soil properties but also seed germination. The aim of thisresearch is to checkmate the effect crude oil pollution has on soil fertility, seed germinationand microbial activity. Two different agricultural soils from Ibeno and Otuocha collected bycomposite sampling were used to conduct the study. The crude oil for carrying out the research was sterilized with a micron Chromafil CA/S % 45 syringe filters. The physicochemical analysis of the soil and its microbiological enumeration was done. This was followed by the artificial pollution of the soil with fresh crude oil. Soil’s physicochemical properties and microbiological enumeration were analyzed followed by the planting of bean seed son the polluted soil. Unpolluted soils was also planted and served as the control. The artificial pollution of the soils’ increased physicochemical properties like cation exchange capacity, selenium, mercury, arsenic, carbon and phosphorus in both soil. Some physicochemical properties like electrical conductivity, salinity, vanadium, zinc, cadmium, iron, manganese, copper, cobalt, nickel and nitrogen decreased in both soils. Water permeability was positive and became negative after pollution. Soil texture was bound and became loose after pollution. Other soil properties like pH increased in Ibeno soil but decreased in Otuocha soil. The number of microorganisms decreases after pollution. Statistically, cultivated beans germinated faster on unpolluted soil and appear healthier than polluted soil because of slow germination and a wrinkled appearance. This study shows that crude oil pollution has a significant effect on soil fertility, seed germination and microbial activity.

Impact of cassava mill effluent on the microbial population and distribution in polluted soils in Abakaliki, Ebonyi State, Nigeria

Cassava mill effluent generated from cassava processing when discharged to the soil, altersthe nature of soil properties and also becomes a major cause of environmental degradation.This research characterized bacteria and fungi distributed in cassava effluent polluted soils inAbakaliki, Ebonyi State, Nigeria. Soil samples were collected over a period of three monthsusing a sterile soil auger into a sterile sample zip bag for analysis. The bacterial count from thedifferent sites varied significantly (p&lt;0.01). The total colony count of bacteria from the effluent obtained from rice mill cassava processing sites ranged from 4.0±0.2x106 CFU/g to 8.6±0.8x106 CFU/g. During August, the bacterial loads also differed very significantly (p&lt;0.01) ranging from 3.3±0.3x106 CFU/g to 6.5±0.6x106 CFU/g across the locations. Similarly, the fungal count varied significantly (p&lt;0.01) ranging from 1.7±0.1x106 CFU/g to 3.4±0.3x106 CFU/g across the locations in June. The bacteria species isolated from the polluted soil sample include E.coli, Staphylococcus spp, Klebsiella pneumoniae, Shigella spp, Pseudomonas aeruginosa and Proteus spp, while the fungal species identified include Articulospora inflata, Trichoderma spp, Aspergillus spp and Penicillium spp. These organisms were also present in the unpolluted soil samples except for Articulospora inflata which was solely isolated from polluted soil sample in some of the sampled sites. This study has shown that bacterial population was higher in cassava mill polluted soil compared to the unpolluted sites. Whereas, the fungal population indicated only a mild increase in the polluted compared to the unpolluted sites.

Remediation of crude oil contaminated soil with locally formulated bioremediation agent

Hydrocarbon pollution is one of the major environmental challenges facing the Niger Delta region of Nigeria, and over the years, various methods and strategies have been suggested to be used in tackling these problem. This research was aimed at restoring crude oil contaminated soil with locally formulated bioremediation agent (coded LOFBA). The local bioremediation agent (LOFBA) formulated consisted of cow dung, chicken droppings and periwinkle shells. Four soil treatments (unpolluted soil, polluted soil with crude oil, polluted soil remediated with LOFBA and polluted soil remediated with NPK) were setup using completely randomized blocked design (CRBD). The microbial isolates were identified on the basis of cultural, morphological and biochemical characteristics. Physicochemical properties of the soil (pH, total nitrogen, sulphate, phosphorus, total organic carbon, moisture, exchangeable cations, heavy metals) were estimated using standard procedures while total petroleum hydrocarbon (TPH) and polycyclic aromatic hydrocarbons (PAH) were determined using the gas chromatography-mass spectroscopy (GCMS). The LOFBA had pH 5.6, high calcium (47.325%), Nitrogen (1.49%), phosphorus (0.26%), electrical conductivity (194.81μmho/cm) and high counts of bacteria and fungi. The microbial isolates identified were Bacillus subtilis, Bacillus megaterium, Bacillus cereus, Acinetobacter aceti, Corynebacterium diphtheriae, Pseudomonas aeruginosa and Streptococcus pyogenes. Soil remediated with LOFBA showed a significantly (p &lt; 0.05) higher bacterial counts total nitrogen and exchangeable ions (K, Mg, Na and Ca) than other treatments. Heptadecane, pristine, octadecane, eicosane, herieicosane and hentriacontane were more highly degraded in LOFBA remediated soil than NPK remediated soil. Naphthalene was the only PAH present in all soil samples after six months although LOFBA remediated soil had the lowest concentration. Besides, Acenaphylylene was detected in crude oil contaminated soil and soil remediated with NPK while none was detected in soil remediated with LOFBA. The results also revealed that total petroleum hydrocarbon (TPH) from unamended soil decreased from 21.33 mg/kg to 16.61 mg/kg (22.13% degradation), from 15.18 mg/kg to 3.03 mg/kg (80.04% degradation) in LOFBA remediated soil while that of NPK remediated soil decreased from 18.70 mg/kg to 7.97 mg/kg (57.38% degradation) after six months. The results indicate that the locally formulated bioremediation agent (LOFBA) enhanced the recovery of the oil contaminated soil better than NPK fertilizer. LOFBA is therefore, recommended for oil spill remediation in the tropic.

Influence of firefighting fluorosynthetic film forming foam on soil microbocenosis

Per- and polyfluoroalkyl substances (PFASs) are a group of over 5000 different chemicals that are used in a wide range of industrial applications and consumer products. Perfluoroalkyl substances have unique properties, such as high chemical stability and surface activity, which leads to their widespread use in medicine, science and everyday life. Aqueous film forming foams (AFFFs) are complex proprietary formulations that contain percent levels of PFASs as well as solvents and hydrocarbon surfactants which, when combined, afford AFFF the functionality required for its purpose. Firefighting foams, such as AFFF, are used primarily to control fires involving flammable liquids such as fuel and oil. AFFF suppresses fire by producing a film over the fuel/oil fire that effectively starves the fire of oxygen. The carbon-fluorine bond makes these compounds extremely strong and stable. This chemical and thermal stability allows these substances to persist in the environment without breaking down. While biological effects of single PFAS have been studied, the effects of PFAS-containing mixtures, such as AFFF, are unknown. The environmental effects of firefighting foam pollutants are generally considered in terms of their toxicity and their biodegradability. Firefighting foams have been found to have a negative impact on the environment (e.g. can remove oxygen from aquatic environment in turn killing aquatic fauna). The effect of PFAS on the microorganisms is not sufficiently studied. To date, there are few studies on the structure and dynamics of microbes in the presence of per- and polyfluoroalkyl substances. Moreover, the results are contradictory. In this regard, it is important to study the impact of various PFAS chemicals on the microorganisms. The article presents the results of the effect study of a fluorosynthetic film forming foam, the main component of which is perfluorinated organic acid, on soil microorganisms, namely ammonifiers, oligonitrophils and nitrogen-fixing microorganisms, yeasts and molds, actinobacteria, and cellulose-degrading bacteria. It was accomplished by plating a sample of the soil that has been serially diluted in water and enumeration of colony forming units (CFU) per gram of soil. The number of soil microorganisms was counted two weeks and three months after contamination with a fluorosynthetic film forming foam. The control sample was unpolluted soil. The sample of soil (1.0 g) was mixed and suspended with a 10 ml of water in a tube for isolation and enumeration of microorganisms. The sample was shaken vigorously to separate organisms from the colloidal material surrounding soil particles. Obtained suspension was serially diluted from 10-2 to 10-6. Aliquot of each dilution was plated onto suitable agar medium. Meat-peptone agar, wort agar, starch-ammonia agar, ashby's agar and hutchinson's agar were used to isolate different groups of microorganisms from gray forest soil and to study the effect of film forming foam on them. The plates were incubated at 28 °C for 3–14 days and the results are expressed as CFU per gram of soil. Colonies of bacteria on meat-peptone agar and ashby's medium were counted after 3–4 days, yeasts and fungi on wort agar after 4–5 days and actinobacteria on starch-ammonia medium after 7–10 days. The number of colonies of cellulose-degrading microorganisms was counted after 14 days cultivation. Firefighting fluorosynthetic film forming foam led to the soil microbial community restructuring and a microbial diversity decrease. The study revealed a decrease the number of different groups of soil microorganisms two weeks after the pollution with the firefighting fluorosynthetic film forming foam, in particular ammonifiers by 2 times compared to the control, nitrogen-fixing microorganisms by 2.7 times, actinobacteria by 4.7 times, yeasts and fungi by 2.8 times. Three months after soil contamination with AFFF the number of nitrogen-fixing microorganisms, actinobacteria, yeasts and fungi increased by 1.85, 1.2 and 2.6 times compared to the control respectively. The number of ammonifiers and cellulose-degrading microorganisms decreased by 1.7 and 5.0 times compared to the control respectively.

Accumulation of livestock manure–derived heavy metals in the Hexi Corridor oasis agricultural alkaline soil and bioavailability to Chinese cabbage (Brassica pekinensis L.) after 4-year continuous application

Hexi Corridor is one of the most important base of vegetable producing areas in China. Livestock manure (LM) applied to agricultural field could lead to soil heavy metal (HM) pollution. Previous studies have focused on HM pollution following LM application in acidic polluted soils; however, fewer studies have been conducted in alkaline unpolluted soils. A 4–year field vegetable production experiment was conducted using pig manure (PM) and chicken manure (CM) at five application rates (0, 15, 30, 45, and 60 t ha−1) to elucidate potential risks of HMs in an alkaline unpolluted soil in the Hexi Corridor oasis agricultural area and HM uptake by Chinese cabbage. The results showed that LM application caused a significant build–up of Cu, Zn, Pb, Cd, and Ni content in topsoil by 30.6–99.7%, 11.4–51.7%, 1.4–31.3%, 5.6–44.9%, 14%–40.8%, respectively. The Cd, Cu, Zn could potentially exceed the soil threshold in next 8–65 years after 15–60 t ha−1 LM application. Under LM treatment, the soil DTPA–extractable Cu, Zn, Fe, the acid–extractable fraction of Cu, Zn, Fe, Cd, Ni, and the Oxidable fraction of Cu, Zn, Fe, Mn, Cd, Ni significantly increased, but the DTPA–extractable Pb, Cd, the acid–extractable fraction of Pb, and the reducible fraction of Cd significantly decreased. Cu and Zn could migrate to the deeper soil and relatively increase in DTPA–extracted Cu, Zn were found in 20–40 cm soil depth after LM application. The pH and SOM could influence the bioavailability of HMs in soil. The bioaccumulation factor and transfer factor (TF) values were <1 except Mn (TF > 1). HMs in leaf did not approach the threshold for HM toxicity due to the “dilution effect”. Recommend the type of manure was the PM and the annual PM application rate was 30 t ha−1 to ensure a 20–year period of clean production in alkaline unpolluted Fluvo–aqiuc vegetable soils.

Micronucleus Induction in Vicia faba Root Tips by Crude Oil-Polluted Soil from Ecuadorian Amazon

In the past four decades, the Amazon rainforest has emerged as a crucial zone for crude oil extraction in the South American region. In the Ecuadorian Amazon rainforest, hydrocarbon blocks (called “bloques”) cover vast zones, including agricultural and livestock farms, protected natural regions and the territories of uncontacted indigenous tribes. This study proposes a micronuclei assay on Vicia faba following a 24 h exposure to various soil samples collected from Bloque 57 in Ecuador. Sampling was conducted between the Dayuma and Aguarico zones, approximately 30 km from Nueva Loja city. The research aimed to assess the impact of different soil samples, particularly those from areas affected by crude oil spills, to induce micronuclei and mitotic index changes in V. faba roots. Results: The soil pollution caused by crude oil is not the sole factor contributing to cytotoxicity and genotoxicity in V. faba. Most samples from areas polluted by crude oil outside the small-scale farm showed no significant difference in micronuclei rate compared to negative control and Amazon unpolluted soil. Conversely, samples from the small-scale farm displayed a statistically significant genotoxic effect. Furthermore, samples collected from open-air wastewater pools demonstrated higher levels of cytotoxicity compared to the controls and those from small-scale farms. The mitotic index was lower in seedlings exposed to wastewater in open-air pools, especially for the 20 cm deep samples. This phenomenon could be linked to bitumen-like substances and oils floating on the surface, attaching to the small roots and causing suffocation.

Soil properties determine the impact of nZVI on Lactuca sativa L and its rhizosphere

Nanoscale zero-valent iron (nZVI) is a promising material tool for the remediation of metal(loid)-contaminated soils since it reduces metal(loid) availability and plant uptake, thereby enhancing the development of the plants. However, the effects of nZVI as nanoparticles on soil properties, plants, and the microbial rhizosphere in unpolluted soils are poorly understood. Here we tested the impact of nZVI at different doses (0.5 and 5% of commercial suspension) on soil properties, lettuce plants, and their microbial rhizosphere in two non-contaminated soils with distinct physico-chemical properties (alkaline versus acidic soil). To this end, a pot experiment was performed with lettuce plants in a growth chamber for a month. Both soils showed an increase in of pH and available Fe after nZVI application. However, these effects were more marked in the acidic soil. In this regard, the plants in this soil showed increased biomass and Fe content. TEM analysis revealed that although the roots and leaves of plants grown in the alkaline soil showed better cell integrity than those in acidic soil—an observation that was consistent with the visual appearance of the plants—the former were more affected by the nZVI treatment. Regarding the microbial rhizosphere, in general, nZVI enhanced enzyme activity regardless of the soil type. Microbial functional diversity showed a significant decline in response to nZVI in alkaline soil. In contrast, the 0.5% nZVI treatment had a positive effect on this parameter in acidic soil. Bacterial genetic diversity was less affected by the presence of nZVI than fungal diversity, which was higher in nZVI-treated acidic soils. In addition, alterations of bacterial and fungal communities were associated with available Fe in acidic soil. In conclusion, soil properties play a key role in determining the effects of nZVI on lettuce plants and their rhizosphere.