Metal Concentrations In Soils Research Articles

Physico-Chemical and Thermodynamic Adsorption Studies of A Few Soils from Delta and Oyo State, Nigeria

Comprehensive study of the physico-chemical properties and interactions of cations with soils is a crucial research need for the development of more sustainable agricultural systems. The analysis of physico-chemical and thermodynamic adsorption studies of various soils from Delta and Oyo State, Nigeria, is the main emphasis of this paper. Two surface soils from the Cocoa Research Institutes of Nigeria (CRIN) and the Isoko North Local Government of Delta State were compared for their physico-chemical properties and heavy metal speciation. The effects of adsorption duration, pH, initial sorbate concentration, and ionic strength were also studied in relation to the adsorption of Cd2+, Pb2+, Cu2+, and Zn2+ ions. On the equilibrium and thermodynamics of the adsorption process, more investigation was conducted. The physico-chemical studies revealed that soil from CRIN had a pH of 6.1 in water and 5.4 in KCl, whereas soil from Isoko North had a pH of 4.3 in water and 3.0 in KCl. The largest percentages of organic matter are found in the soil from Isoko North (3.07%) and CRIN (3.82%). For both soils, the order of exchangeable bases was Ca > K > Mg > Na. The heavy metal concentrations in both soils were in the following order: Zn > Cu > Ni > Pb > Cd = Al; CRIN: 3.82meq/100g for CEC; Isoko North: 2.85meq/100g for CEC. In contrast to CRIN soil, Isoko North soil showed a larger bulk density and a superior hydraulic conductivity. Extractable elements were present in both soils in the following order: Mn > Fe > Zn > Cu. The base saturation in the CRIN soil was higher than the base saturation in the Isoko North soil, which was lower at 60.73%. Zn, Pb, and Cd were the outcomes of the heavy metal speciation for both soils. The equilibrium adsorption data, which were closely related to the Langmuir isotherm model, showed that the maximum capacity of lead for soil from Isoko North was 5.8140 mmol/g and for soil from CRIN was 7.6335 mmol/g. Thermodynamic investigations showed that the adsorption process was spontaneous for simply Cu2+ (for soil from CRIN) and non-spontaneous for other metal ions from both soils. Metal ions from both soils displayed exothermic and endothermic adsorption, respectively, for Cd2+ and Cu2+ (for soil from CRIN).

Environmental pollution status and health risk assessment of selective heavy metal(oid)s in Iran's agricultural soils: A review

The assessment of heavy metal(oid) concentrations in agricultural soil holds significant importance due to its impact on crop safety and quality, as well as the potential risks it poses to human health. This review utilized secondary online published data to evaluate the contamination levels of seven HMs (As, Cd, Cu, Cr, Ni, Pb, and Zn) in Iranian farmland soils. As a result, 31 research papers were collected to compile a dataset offering a comprehensive analysis of HM concentrations, distribution, sources, ecological risks, and potential health risks. The findings indicated that mean concentrations of Ni and Cd exceeded their corresponding permissible levels in farmland soils, while other HMs remained below this threshold. The mean Igeo (geoaccumulation index) values followed the sequence Ni > As > Cu > Cr > Zn > Pb > Cd, with Igeo values suggesting low to slight enrichment for the studied HMs. Pollution index (PI) results revealed notable contamination of As in various provinces, including Kurdistan, Hamedan, Tehran, Mazandaran, West Azerbaijan, Kermanshah, Hormozgan, Golestan, and the Kamfiruz region of Fars. Elevated contamination of Pb and Cd was observed in Fars (Shiraz region), and Cr and Ni in the Sabzevar area farmland soils. As, Cd, and Cu exhibited higher ecological risks (EI) compared to Zn, Cr, Ni, and Pb. The potential ecological risks (PER) ranged from 9.9 to 244.6, indicating low to moderate risk levels. Non-carcinogenic assessments indicated that ingestion was the primary exposure pathway to HMs in Iranian farmland soils, followed by inhalation and dermal contact. Total hazard index (HI) values for studied HMs did not exceed 1, indicating no significant non-carcinogenic risk for both population age groups. This study highlights the current lack of well-documented scientific reports on the status of HMs in agricultural farmland soils across 12 other provinces in Iran, emphasizing the need for further investigation. Moreover, the bioavailability of HMs in agricultural soils significantly influences HM content in crops, underscoring the need for future research to ascertain HM concentrations in different soil fractions.

Is the use of a geotextile a necessary rehabilitation strategy to mitigate tailings contamination in soil cover materials? A 7-year field study

The potential pollution risk associated with poor management of mine tailings includes metal pollution of the surrounding environment from dusting and runoff. Thus, the establishment of a vegetation cover (rehabilitation) is viewed as an effective management strategy. Mine tailings can be inhibitory to plant growth due to their physico-chemical characteristics such as extreme pH, high salinity and potential high metal(loid) content, and the provision of a cover soil (≥ 30 cm) is usually recommended. This requires significant volumes of topsoil, which are often in limited supply at mine sites. An alternative may be the use of engineered soil (using organic and/or inorganic additives to improve physico-chemical properties) and placement of a barrier layer to prevent migration of tailings water or fines into the soil cover medium.Metal(loid)s content in soil cover treatments and vegetation uptake were evaluated after 7 years of rehabilitation in 1 m3 plots on a Pb/ Zn TSF. Final 30 cm covers included unamended tailings, subsoil material and subsoil amended with organic wastes (Spent Mushroom Compost (SMC) and Compost like output (CLO)). Treatments were divided into with/without geotextile inclusion. Soil samples were taken at 0–10 cm and 10–20 cm and analysed for pH, salinity (EC), and metal(loid)s/elements (As, Pb, Zn, Ca, Mg, Mn and, K) content. Vegetation was sampled after 1 yrs. growth (2015) and again after 7 years (2021) and analysed for their metal(loid)s/element content.Unamended tailings showed high metal(loid)s content at both depths, but concentrations were much lower in soil treatments. Herbage samples analysed in 2015 showed a higher concentration of metals than for 2021, highlighting the effectiveness and sustainability of amendments over a long period. Vegetation grown in unamended tailings showed the highest content of metal(loid)s, with significantly lower content in soil treatments. No significant difference was found for soil or vegetation metal(loid) content between geotextile inclusion/ exclusion. Results, highlight the relatively shallow soil covers without geotextile provide long term success with no evidence of metal(loid) contamination from underlying tailings.

Evaluation Heavy Metals Pollution in the Soil from some Regions of Al-Diwaniyah City / Iraq

Soil is the surface layer of the earth’s crust in which plant roots grow and some animals and other microorganisms live in it and it is considered the basis of the ecosystem, so its contamination negatively impact the health of all living organisms, especially humans who are at the top of the food chain. Heavy metals are considered among the most prominent inorganic pollutants in the soil, so this study came to evaluate the concentrations of some toxic heavy metals in areas with different activities in the city of Diwaniyah. The results of the study showed that the concentrations of heavy metals in the surface soil ranged between (0.958-2.292 mg/kg) and (19.132-73.907 mg/kg), (14.882 - 50.012 mg/kg) and (29.689-62.109mg/kg) for cadmium, lead, copper and chromium, respectively, and their concentrations in the soil at depth of 30 cm ranged between (1.529-1.971 mg/kg), (22.160 - 99.885 mg/kg), (12.790-55.630 mg/kg) and (41.278-75.467 mg/kg) for cadmium, lead, copper and chromium, respectively. Soil pollution was evaluated by using some pollution indices such as the geological accumulation index, pollution load index, contamination factor and degree of pollution. The results of pollution indices showed that the surface soil of the surface study sites and depth of 30 cm is contaminated with a very high degree of cadmium. Medium pollution with lead and little pollution with copper and chromium, and this requires great attention in order to reduce soil pollution with heavy metals, especially cadmium and lead.

Use of Some Natural Materials to Reduce Concentrations of some Heavy Metals in Polluted Water and Possibility of Using Them for Irrigation in Calcareous Agricultural Soils

To evaluate efficiency of some natural materials in using them as filters to reduce concentrations of some heavy elements in polluted water, and possibility of using them for irrigation in calcareous agricultural soils, two experiments were conducted, first is laboratory, which is treatment of various polluted waters, namely industrial water, gray water, and river water using three natural treatment materials as filters, which are activated charcoal, Eichhornia crassipes plant powder, Ceratophyllum plant powder. Poles made of polyethylene were used with a length of 100 cm and a diameter of 10 cm equipped with a tap from bottom, a layer of glass wool was placed at bottom, and then treatment materials were placed on top of it at a height of 50 cm. A piece of gauze cloth was placed over it for filter polluted water from solids. Polluted water was passed after filtering from top of column and left for 24 hours for equilibrium, then filtrate was collected from bottom of column. Second experiment, it is biology, as an experiment was conducted in pots of 20 kg capacity, using calcareous soil with a Loamy texture, and Dodonaea seedlings (one of fence plants) were planted. NPK fertilizers were added to it according to fertilizer recommendation, and irrigation was done with tap water after 50% of available water was depleted by gravimetric method. Results showed the following: 1-High concentrations of heavy metals, each of Lead, Ccadmium, Zinc and Nickel in industrial water, where they reached 5.190, 0.043, 3.727 and 0.371 mg L-1, respectively, exceeding limits allowed by World Food and Health Organization for each of Cadmium, Zinc and Nickel, while concentrations of Lead is within internationally permitted limits. As for gray water, Cadmium concentrations exceeded internationally permitted limits, while concentrations of Lead, Zinc and Nickel were within internationally permitted limits. In river water, they were within internationally permitted limits. 2. Decreased concentrations of heavy metals in polluted water treated with various natural treatment materials compared to their concentrations before treatment. The materials used in treatment can be arranged according to their efficiency in adsorption of heavy metals from industrial and gray water as follows: -activated charcoal > Eichhornia crassipes powder > Ceratophyllum powder > Arundo donax plant_powder. 3-High available concentrations of heavy metals in soils passed through polluted water compared to soils irrigated with treated water. Total concentrations were 34.436, 18.227, 8.064 mg kg-1 soil, 31.064, 16.884, 6.190 mg kg-1 soil, 32.860, 12.670, 4.930 mg kg-1 soil, 0.465, 3.680, and 0.590 mg kg-1 soil for Lead and Cadmium elements and Zinc and Nickel in succession and industrial water and gray water and river water successively, after 100 days of cultivation. 4-High concentrations of heavy metals in plants irrigated with different polluted water compared to plants irrigated with different treated water after 100 days of cultivation. Plants irrigated with polluted and treated water can be arranged according to concentration of heavy metals in them as follows: - industrial water > gray water > river water.

Reuse and Mechanochemical Processing of Ore Dressing Tailings Used for Extracting Pb and Zn

The increasing accumulation of rock waste obtained due to ore processing and its environmental impacts, such as acid mine drainage and elevated concentrations of heavy metals in soils, necessitates the transformation of mining technologies based on the concept of circular waste management. The research is aimed at improving the parameters of the mechanical activation effect produced on technogenic georesources, as well as at expanding the application scope of disintegrators in the field of using the partial backfill of the mined-out space when developing stratified deposits. In this regard, the research purpose was to substantiate the parameters of extracting metals from enrichment tailings using their mechanochemical activation to ensure cyclic waste management. The research involved the application of three-dimensional interpolation methods used for processing the data and the graphical representation. As a result, the following was found to be characteristic of the waste of the Sadonsky mine management. The degree of extracting zinc from pre-activated tailings increases logarithmically when the H2SO4 concentration and the NaCl proportion decrease 3.5 times. The degree of extracting lead from the activated tailings increases according to the Fourier law when decreasing the NaCl mass concentration, and an optimal range of the H2SO4 (0.38–0.51%) proportion decreases six times. One of the key results of the research is the justification of expanding the scope of applying disintegrators in the case of a directed activation influence exerted on the components of the stowing strips. The obtained results expand the understanding of the mechanism of the influence of the mechanochemical activation of dry tailings on the reactivity unevenness when extracting several metals from them.

THE HEAVY METAL CONSTITUENTS AND COMPOSITION OF THE SOIL AND MUSHROOMS COLLECTED FROM THE NONG-AUNG PUBLIC FOREST

This paper presents the findings of a study conducted to assess the conditions and heavy metal contents of the soil in areas of the Nong-Aung public forest. This study investigates the relationship between the heavy metal contents in soil and the accumulation of heavy metals in naturally occurring mushrooms within the public forest, comparing the components of a waste disposal zone and a general disposal zone. This study employs one-way analysis of variance to analyse variances between groups, with data differences compared using the least significant difference method. The research reveals significant differences (p < 0.05) in the heavy metal contaminants present in soil between the waste disposal zone and the general zone in the public forest. Human activities are found to influence soil properties and heavy metal content. However, it is important to note that the levels of heavy metals in the Nong-Aung public forest do not exceed Thailand’s standards. The study also examines the heavy metal content in various mushroom species, including Mycoamaranthus cambodgensis (Pat.) Trap, Ganoderma applanatum (Pers.ex Wallr.) Patouillard, Heimioporus japonicus (Hongo) E. Horak, Thaeogyroporus porentosus (berk. ET. Broome) and total mushrooms suitable for consumption. The research reveals that the mushrooms have an average Cd content of 0.558 ± 0.908 mg/kg dry weight, with quantities of other elements as follows: Pb 1.740 ± 2.441 mg/kg dry weight, Mn 266 ± 128 mg/kg dry weight, Ni 4.44 ± 2.83 mg/kg dry weight, and As 0.014 ± 0.005 mg/kg dry weight. Importantly, the heavy metal content of mushrooms in the public forest does not exceed the established standards. However, the study highlights concerns regarding the quality of soil in the public forest and its potential impact on the environment and local biodiversity. The paper concludes by emphasising the need for local government and citizen advocacy to impose restrictions on the expansion of waste disposal areas in the public forest.

Environmental analysis of heavy metal pollution in Mtondia dumpsite, Kilifi County, Kenya.

Dumping and open burning of waste with no regard to environmental implications is a common occurrence in Kenya. In several health surveys in communities close to dump sites, a wide range of human health problems, such as respiratory symptoms, allergies, irritation of the skin, and gastrointestinal problems, have been reported. The issue of heavy metal pollution brought about by the dump sites has become of concern in recent studies. Heavy metal contamination occurs when their concentrations exceed the recommended limits in the soil, water, or plant resources and have negative effects on humans or animals. The accumulation of heavy metals in agricultural soils is of great concern due to food safety issues, potential health risks, and detrimental effects on the soil’s ecosystems. The samples were obtained through random sampling and analysed in the laboratory using the Energy Dispersive X-ray Fluorescence (EDXRF) technique. The EDXRF technique software was used to calculate the qualitative and quantitative aspects of the heavy metals. SPSS version 22 was used to calculate Pearson's correlation coefficient. It was observed that the soil and plants sampled from the dumpsite recorded higher levels of heavy metals than the control samples. This showed that the soils at the dumpsite were more polluted with heavy metals as compared to those at the farms. The mean concentrations of the heavy metals in soil during the dry season followed the trend Zn>Mn>Pb>Cu>Ni>Co>Cr>As. In conclusion, it was observed that the resources (soil, plants, water, and fish) were indeed polluted with various heavy metals. However, the levels do not exceed the permissible limits set by the WHO and FAO.

Impact of Polluted Soil on Herbivory of Leaves and Pneumatophore Growth of Black Mangroves (Laguncularia racemosa) at Eagle Island, River State, Nigeria

Mangroves are ecosystem along the shoreline of Nigerian coast and area of active oil exploration in Nigeria. This study is on the impact of pollution on herbivory and pneumatophore growth in black mangrove at Eagle Island. Leave herbivory, pneumatophore growth, THC and heavy metal concentration in soil, root and leave were determined. The sample site was divided into: plot A (high muddiness), plot B (low muddiness), plot C (slight muddiness) and Control (little or no pollution). Random sampling was used in obtaining leaves, soil and pneumatophore from each plot. Pneumatophore height was taken with meter rule and the weight with weighing balance. The leaf image was taken using a digital handy scanner and was uploaded in a software called Image J to measure the area consumed. EPA Method 418 was used to test for Total Hydrocarbon Content (THC). Heavy metals (Cadmium, Lead, Zinc) were determined using AAS- Atomic Absorption Spectrometric method. Results revealed that control plot had highest leaf consumption (2.200±0.33cm2) compared to other plots. The heavy metals and THC concentrations in different plant parts (leaves and roots) revealed that THC was high in leaves (250.88±95.33mg/kg), while heavy metals were high in root The pneumatophores were taller and heavier in Plot A compared to Plots B and C. This study shows that pollution affects herbivory and pneumatophores growth in mangroves forest. Mitigation measures should be taken to prevent these pollutants.

Spatial and Temporal Distribution and Source Analysis of Heavy Metals in Agricultural Soils of Ningxia, Northwest of China

The spatial and temporal dynamic monitoring of the heavy metal concentration in agricultural soils can help us to understand the extent and changes of regional soil heavy metal pollution, allowing us safeguard food safety and human health and provide basic data for the prevention and control of heavy metal pollution in agricultural soils. The heavy metals’ concentrations, including Cd, Cr, Cu, Hg, Ni, Pb, Zn, and As, were measured in surface (0–20 cm) soil samples collected in 2017 and 2021 from agriculture land to evaluate their pollution levels in the Ningxia Hui Autonomous Region (Hereinafter referred to as Ningxia), northwest of China. A correlation analysis, principal component analysis, and positive matrix factorization were used jointly to identify possible sources. The results showed that, for most soils, the concentrations of As, Cr, Cu, Ni, Pb, and Zn were lower than the contamination thresholds stipulated by the national guideline. The average concentrations of As, Cd, Zn, and Ni in 2021 were significantly lower than the levels in 2017 (p < 0.05), but the average concentration of Cu was significantly higher in 2021 than in 2017 (p < 0.05), and the average concentrations of Cr, Pb, and Hg did not change significantly during the last five years. According to the pollution assessment index (mean Igeo values), Cd and Hg were found to accumulate in the farmland environment and were the major pollutants in the region, and the hotspots with high concentrations of heavy metals were mainly located in the Yellow River irrigation area in Northern Ningxia. Four main sources of heavy metals in the soils were identified: As mainly originated from natural sources; Pb, Cd, and Ni from atmospheric deposition and industrial activities; Cr, Zn, and Cu from agricultural activities; and Hg from the coal-related industrial activities. The concentration of heavy metals from anthropogenic sources accounted for 77.10% in agricultural soils, indicating the strong influence of this source on soil heavy metal accumulation. These findings provide scientific evidence and valuable information to prevent heavy metal contamination and control of farmland.

Regional Inversion of Soil Heavy Metal Cr Content in Agricultural Land Using Zhuhai-1 Hyperspectral Images.

With the development of hyperspectral imaging technology, the potential for utilizing hyperspectral images to accurately estimate heavy metal concentrations in regional soil has emerged. Currently, soil heavy metal inversion based on laboratory hyperspectral data has demonstrated a commendable level of accuracy. However, satellite images are susceptible to environmental factors such as atmospheric and soil background, presenting a significant challenge in the accurate estimation of soil heavy metal concentrations. In this study, typical chromium (Cr)-contaminated agricultural land in Shaoguan City, Guangdong Province, China, was taken as the study area. Soil sample collection, Cr content determination, laboratory spectral measurements, and hyperspectral satellite image collection were carried out simultaneously. The Zhuhai-1 hyperspectral satellite image spectra were corrected to match laboratory spectra using the direct standardization (DS) algorithm. Then, the corrected spectra were integrated into an optimal model based on laboratory spectral data and sample Cr content data for regional inversion of soil heavy metal Cr content in agricultural land. The results indicated that the combination of standard normal variate (SNV)+ uninformative variable elimination (UVE)+ support vector regression (SVR) model performed best with laboratory spectral data, achieving a high accuracy with an R2 of 0.97, RMSE of 5.87, MAE of 4.72, and RPD of 4.04. The DS algorithm effectively transformed satellite hyperspectral image data into spectra resembling laboratory measurements, mitigating the impact of environmental factors. Therefore, it can be applied for regional inversion of soil heavy metal content. Overall, the study area exhibited a low-risk level of Cr content in the soil, with the majority of Cr content values falling within the range of 36.21-76.23 mg/kg. Higher concentrations were primarily observed in the southeastern part of the study area. This study can provide useful exploration for the promotion and application of Zhuhai-1 image data in the regional inversion of soil heavy metals.

Industrial hemp (Cannabis sativa L.)—a valuable alternative crop for growing in agricultural soils contaminated with heavy metals

Hemp (Cannabis sativa L.) is a multiuse plant, which has been abundantly studied for phytoremediation purposes in recent years. The majority of experiments were performed in greenhouses with potted plants where hemp showed promising results. Only few studies tested hemp on site in heavy metal–polluted agricultural soil in real environmental conditions and practical assessments of hemp phytoremediation feasibility are lacking. We conducted a comprehensive study using 2 legal industrial hemp varieties (Futura 75 and Tisza) at three differently polluted locations (heavily polluted location, HP; moderately polluted location, MP; and slightly polluted location, SP) in the heavy metal contaminated Celje valley in Slovenia and determined the content of Pb, Zn, and Cd in 5 plant organs/tissues. The yield of each organ/tissue was determined as well to enable us to calculate the phytoremediation potential (PP). On average, plants grown in the HP location accumulated the highest values of all examined elements, followed by plants from the MP location and plants from the SP location, showing that the content of heavy metals in soil influences the accumulation in plants. Accumulation of Pb/Zn/Cd by plant organs/tissues was distributed in the following order: inflorescences (Pb-4.10/Zn-92.8/Cd-0.50 mg/kg) > seeds (Pb-1.79/Zn-92.6/Cd-0.27 mg/kg) > roots (Pb-1.15/Zn-15.0/Cd-0.44 mg/kg) > stem bark (Pb-0.42/Zn-12.4/Cd-0.23 mg/kg) > stem woody core (Pb-0.34/Zn-4.6/Cd-0.15 mg/kg). The only exception was for Cd, where roots accumulated a higher value than seed, yet lower than inflorescences. PP was calculated by multiplying hemp tissue/organ yield by the relative concentrations of heavy metal. The highest PP for Pb and Cd were achieved at the HP location (3.80 and 0.23 g/ha/vegetation period). On the other hand, tissue/organ yield was more important for high PP of Zn, where the SP location reached the highest PP for Zn (148.5 g/ha/vegetation period) due to the highest yields. Only seeds from HP and MP locations accumulated a too high content of Pb; otherwise, all other fibers and seeds can be safely used in the textile and food industry. Results of this study showed that hemp cannot be considered an efficient plant for the phytomanagement of contaminated areas. Nevertheless, hemp cultivation in heavy metal–polluted agricultural soils seems feasible since the majority of tissues/organs were not contaminated and different products can be obtained from various parts of the hemp plant.

Bioaccumulation and Mobility of Heavy Metals in the Soil-Plant System and Health Risk Assessment of Vegetables Irrigated by Wastewater

Accumulation of heavy metals in soil and vegetables is presently a challenging environmental concern worldwide. The present study was designed to elucidate heavy metals contamination of vegetables irrigated with domestic wastewater and associated health risks. The study area comprises three zones: Kot Addu, Alipur, and Muzaffargarh. A total of 153 samples of wastewater, topsoil, and vegetables were analyzed for physicochemical parameters and concentration levels of eight metal elements (Cu, Fe, Zn, Mn, Pb, Cd, Ni, and Cr) determined through analytical procedures. The outcome of the present investigation reveals that heavy metal concentrations in wastewater, soil, and vegetables irrigated with wastewater were slightly higher than the WHO-suggested limit. The heavy metals concentration observed in vegetables irrigated with wastewater can be ranked in order of Ni > Mn > Cr > Pb > Cu > Fe > Zn > Cd. Transfer factor (TF), daily ingestion of metals (DIM), and health risk index (HRI) were calculated. Spinach exhibited higher values of transfer factor than cabbage, cauliflower, and radish, which were followed by tinda and carrot. Minimum values of HRI were observed for Cr (0.0109) in almost all of the vegetables ingested by adults and children. Cabbage exhibited higher values of HRI for Pb (4.0656) in adults, followed by cadmium (HRI = 2.993). Minimum values of HRI were calculated for Cd (0.0115; child). Cauliflower exhibited higher values of HRI (5.2768) for Pb in children. Pb, HRI values (4.5902) were observed in adults living in Kot Addu. The results exhibited similar trends of HRI in adults and children living in Muzaffargarh and Alipur.

Determining heavy metals in soil and water in a bioremediating area in Nkeleoken-Alode Eleme Community Rivers State.

The study aims at determining the concentration of heavy metals in soil and water undergoing bioremediation in the Nkeleoken-Alode community of Eleme Local Government Area, (p<0.05) in the heavy metal concentrations Rivers State, carried out on both soil and aquatic between the test and control sites. The various sites undergoing bioremediation in the area. Soil and water samples were collected from three sites: unpolluted, polluted unremediated and polluted remediated sites. 50g of soil sample was collected using sterile aluminium foil, and water samples were collected in 250ml sterile containers. Samples were assayed using an Atomic Absorption Spectrophotometer which measures the concentrations of elements in a liquid sample. The absorption is proportional to the concentration of the elements present in the samples. Results showed a significant difference(p<0.05) in the concentration of lead and chromium in soil samples from polluted remediated sites compared to soil samples from unpolluted sites and polluted unremediated sites. Arsenic, cadmium and nickel did not show a significant difference when soil samples from the polluted remediated site were compared to unpolluted and polluted unremediated sites(p>0.05). Furthermore, there was a significant difference (p<0.05) in the concentrations of cadmium, nickel and chromium in water samples, when water samples from the polluted and polluted unremediated sites. Lead and arsenic in water samples from polluted remediated sites did not show any significant difference (p>0.05) when compared to unpolluted and polluted unremediated sites. The concentrations of heavy metals in the soil and water samples showed a significant increase (p<0.05) in the heavy metal concentrations between the test and control sites. The various areas in the region that have been exposed to pollution pose a serious risk of heavy metal toxicity to occupants of the Niger Delta as a result of crude oil spillage. An immediate bioremediation strategy should be adopted in order the restore lost vegetation and aquatic life.

Association between heavy metal uptake and growth and reproduction in the anecic earthworm, Alma nilotica (Grube 1855).

Elevated heavy metal concentrations in soils are a cause for concern as they are hazardous to soil organisms including earthworms which are considered as ecosystem engineers. Current ecotoxicity tests predominantly use temperate earthworm species, and thus there is the need to include a broader genera of native species to improve ecological risk assessment. Alma nilotica, is a tropical anecic earthworm species that survives well under laboratory conditions and has potential for use in ecotoxicology testing but lacks published toxicity data for important pollutants. Growth and reproduction bioassays were carried out with A. nilotica to determine the relationship between the concentrations of Cu, Zn, Pb and Cr in spiked soils and their bioaccumulation and toxic effects. Positive linear relationships were found between soil-metal and internal earthworm-metal concentrations. Cu did not inhibit growth up to 35 days of exposure but became toxic with longer exposure duration. Zn was not regulated by A. nilotica although it is an essential metal that is well regulated by Eisenia sp. commonly used in standard ecotoxicity tests, showing differences in metal regulation by earthworms of different ecological categories. Based on bioaccumulation factors (BAFs), growth inhibition and reproduction effects the metals were ranked in decreasing toxicity as Pb > Cr > Zn > Cu. The mean 20% Internal Effects Concentrations (IEC20s) for reproduction were 1.04, 2.9, 8.3 and 224.2 mg metal kg-1 earthworm for Pb, Cr, Zn and Cu respectively. These data can contribute to the improvement of metal risk assessment particularly in tropical contexts.

Assessment of environmental pollution using indices, transfer factor and source apportionment in soils and plants of wetlands in Northern Nigeria

ABSTRACT This study assessed metal pollution in wetland ecosystems in North-western Nigeria, which is susceptible to pollution from various sources including agriculture, industry and urbanisation. The study analysed the concentrations of lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd) and iron (Fe) in wetland soils and plants from 10 sites in the region. Pollution indices, including contamination factor, modified degree of contamination, Nemerow pollution index and pollution load index, were used to determine the extent of metal pollution in the study area, while transfer factors were calculated to assess the potential for metal transfer from soils to plants. The results showed that metal concentrations in wetland soils and plants varied widely depending on the location and the metal of interest, with some sites showing higher concentrations due to agricultural and mining activities. The pollution indices indicated that metal pollution was generally moderate to highly polluted in the study areas, with some metals showing higher potential for transfer from soil to plants than others. This study provides valuable insights into the extent and severity of metal pollution in some wetland soils and plants in Northern Nigeria.

Influence of the gene pool of the breed on the content and variability of copper in the liver of pigs

The average level and variability of copper in the liver of pigs of different breeds were studied. Samples of parenchymal organs from pigs were taken immediately after slaughter and analysed at the analytical centre for collective use of V.S. Sobolev Institute of Geology and Mineralogy of the Siberian Branch of the Russian Academy of Sciences using the method of atomic absorption spectrometry with flame and electrothermal atomisation on the SOLAAR M6 spectrometer (USA) by GOST 26929-94 Raw materials and food products— sample preparation Mineralization to determine the content of toxic elements. A normal distribution of the trait was found only in the Landrace breed (W = 0.94). In pig breeding areas, the content of heavy metals in soil, water and feed was studied, which did not exceed the maximum permissible concentration. The most significant variability of the microelement was observed in the Kemerovo breed, the least - in the Landrace breed. The full copper content was marked in the early ripening meat breed and the minimum in the Landrace breed. A smaller interquartile range about the Kemerovo and early meat breeds characterised the level of copper in the liver of Landrace pigs.

Combination of intercropping maize and soybean with root exudate additions reduces metal mobility in soil-plant system under wastewater irrigation

The effects of root exudates and irrigation with treated wastewater on heavy metal mobility and soil bacterial composition under intercropping remain poorly understood. We conducted a pot experiment with maize and soybean grown in monocultures or intercultures, irrigated with either groundwater or treated wastewater. In addition, the pre-collected root exudates from hydroponic culture with mono- or inter-cropped maize and soybean were applied to the soil at four levels (0 %, 16 %, 32 % and 64 %). The results showed that application of root exudates increased plant growth and soil nutrient content. The analysis of “Technique for Order of Preference by Similarity to Ideal Solution” for higher plant biomass and lower soil Cd and Pb concentrations indicated that the best performance of soybean under treated wastewater irrigation was recorded under intercropping applied with 64 % of exudates, with a performance score of 0.926 and 0.953 for Cd and Pb, respectively. The second-best performance of maize under treated wastewater irrigation was also observed under intercropping applied with 64 % of exudates. Root exudate application reduced heavy metals migration in the soil-plant system, with a greater impact in intercropping than in monocropping. In addition, certain soil microorganisms were also increased with root exudate application, regardless of irrigation water. This study suggests that appropriate application of root exudates could potentially improve plant growth and soil health, and reduce toxic heavy metal concentrations in soils and plants irrigated with treated wastewater.

Effect of Soil Composition on Heavy Metal Uptake and Distribution in White Clover (Trifolium repens L.)

Soil contamination with heavy metals is becoming an increasingly global issue, as elevated levels of heavy metals exceeding regulatory limits are diminishing agricultural productivity and consequently endangering human health and the environment. This study aimed to assess the seasonal dynamics, accumulation, and translocation of heavy metals (As, Cd, Cr, Cu, Fe, Pb, Ni, and Zn) in the organs of white clover (Trifolium repens L.) depending on soil content. The heavy metal content in soil and white clover samples was determined using atomic absorption spectrophotometry. The results revealed that the analyzed soil was significantly contaminated with Cu and Zn in the industrial zone (GS) and with Pb near the urban landfill (D3). The content of heavy metals in white clover varied depending on the location and season. It is evident that white clover accumulated certain metals in its roots and leaves during spring, summer, and autumn, including Pb, Cr, Cu, Fe, Ni, and Zn. The analysis results indicated that Fe was the predominant element in white clover roots, while Zn and Fe were most abundant in the leaves. Values of BCF >1 and TF >1 for Zn suggest that white clover is a potential accumulator of this heavy metal.

Comparison between Variable-Selection Algorithms in PLS Regression with Near-Infrared Spectroscopy to Predict Selected Metals in Soil.

Soil is one of the Earth's most important natural resources. The presence of metals can decrease environmental quality if present in excessive amounts. Analyzing soil metal contents can be costly and time consuming, but near-infrared (NIR) spectroscopy coupled with chemometric tools can offer an alternative. The most important multivariate calibration method to predict concentrations or physical, chemical or physicochemical properties as a chemometric tool is partial least-squares (PLS) regression. However, a large number of irrelevant variables may cause problems of accuracy in the predictive chemometric models. Thus, stochastic variable-selection techniques, such as the Firefly algorithm by intervals in PLS (FFiPLS), can provide better solutions for specific problems. This study aimed to evaluate the performance of FFiPLS against deterministic PLS algorithms for the prediction of metals in river basin soils. The samples had their spectra collected from the region of 1000-2500 nm. Predictive models were then built from the spectral data, including PLS, interval-PLS (iPLS), successive projections algorithm for interval selection in PLS (iSPA-PLS), and FFiPLS. The chemometric models were built with raw data and preprocessed data by using different methods such as multiplicative scatter correction (MSC), standard normal variate (SNV), mean centering, adjustment of baseline and smoothing by the Savitzky-Golay method. The elliptical joint confidence region (EJCR) used in each chemometric model presented adequate fit. FFiPLS models of iron and titanium obtained a relative prediction deviation (RPD) of more than 2. The chemometric models for determination of aluminum obtained an RPD of more than 2 in the preprocessed data with SNV, MSC and baseline (offset + linear) and with raw data. The metals Be, Gd and Y failed to obtain adequate models in terms of residual prediction deviation (RPD). These results are associated with the low values of metals in the samples. Considering the complexity of the samples, the relative error of prediction (REP) obtained between 10 and 25% of the values adequate for this type of sample. Root mean square error of calibration and prediction (RMSEC and RMSEP, respectively) presented the same profile as the other quality parameters. The FFiPLS algorithm outperformed deterministic algorithms in the construction of models estimating the content of Al, Be, Gd and Y. This study produced chemometric models with variable selection able to determine metals in the Ipojuca River watershed soils using reflectance-mode NIR spectrometry.