Metal Concentrations In Plants Research Articles

Plant metal concentrations in Theobroma cacao as affected by soil metal availability in different soil types

Beans of cacao (Theobroma cacaoL.) are used to produce a variety of chocolate products. Bioaccumulation of metals at toxic levels through the consumption of contaminated products has been identified as a health concern in humans. Both metal diversity and concentration as well as their interactions in the soil influence essential and non-essential metal uptake in plants; but the effects of these on bioaccumulation of metals in cacao is not understood across diverse soil types. In this study eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) were investigated in 12 soil subgroups belonging to four soil orders across 15 locations in Trinidad, with the aim to investigate the effect of soil metal diversity and concentration on metal bioaccumulation in cacao. Soil metals were extracted using five methods (aqua regia, DTPA, Mehlich 3, nitric acid, and water). Cacao leaf metal concentrations were determined using the USEPA 3052 method. Metal extraction efficiency ranged between methods with aqua regia ≥ nitric acid > Mehlich 3 ≥ DTPA ≥ water across all metals. The soil extraction method that best predicted cacao leaf metal concentrations varied with the metal – Mehlich 3 or DTPA for Cd, Ni, Zn; aqua regia, Mehlich 3, or nitric acid for Pb, and water for Mn. A stepwise regression analysis showed that plant metal concentration can be predicted using soil physicochemical characteristics as well as the concentration of metals in the soil. The importance of soil type on cacao leaf metal bioaccumulation is discussed.

Utilization of rural domestic sewage tailwaters by Ipomoea aquatica in different hydroponic vegetable and constructed wetland systems.

For the utilization of nitrogen and phosphorus in rural sewage tailwaters after biological treatment, four systems were examined regarding their ability to purify tailwaters of rural domestic sewage: a hydroponic vegetable system (HV), a subsurface flow constructed wetland (SFCW), a compound system with HV followed by SFCW (HV-SFCW), and a compound system with SFCW followed by HV (SFCW-HV). Parameters of the four systems were optimized to maximize the utilization efficiency of nitrogen and phosphorus, and the characteristics and pollutant removal efficiency of the process were investigated. Moreover, the edible security of vegetables was also evaluated. Results showed that the optimal hydraulic loadings for the four systems were 0.2, 0.3, 0.3, and 0.3 m3/(m2·d) (the lowest being the HV), respectively. In the combined system of HV-SFCW, high contribution proportions of the HV unit to the removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were obtained, reaching 46.7%, 58.1%, and 53.7%. The heavy metal content of plants harvested met the standards of the National Food Safety Standard Limit of Pollutants in Food (GB 2762-2012). Overall, the compound HV-SFCW system achieved the best performance, ensuring that effluent water quality met national standards and realized the effective utilization of nitrogen and phosphorus.

The Long-Term Effect of Petroleum-Derived Substances and Their Bioremediation on the Host Plant (Vicia faba L.) and a Herbivore (Sitona spp.)

The present study assessed distant-in-time effects of soil contamination with petroleum-derived substances (PDSs) (petrol, diesel fuel and used engine oil) and their bioremediation using ZB-01 biopreparation on the growth of broad bean, content of nutrients and heavy metals in plants, and feeding by imagines and larvae of Sitona spp. The results showed that even after 5 years from the moment of soil contamination by engine oil and diesel fuel, they negatively impacted the growth of broad bean plants. PDSs significantly modified the content of nutrients and generally increased the content of heavy metals in plant organs. These substances also negatively affected the feeding of adult Sitona spp., causing a reduction in the percentage of plants damaged by beetles, and a decrease in the surface of consumed areas on leaves. The ZB-01 biopreparation had a generally positive effect on the morphological features of plants, and its effect on the content of nutrients and heavy metals was variable, depending on the type of contaminant, the analyzed metals or nutrients, and the involved part of the plant. The biopreparation also inhibited the adverse effect of PDSs on the feeding by imago of Sitona spp.

Predicting copper contamination in wheat canopy during the full growth period using hyperspectral data.

The rapid and efficient determination of heavy metal content in food crops is essential for human health and environmental protection. The use of hyperspectral data has become a popular way to predict heavy metal content in plants; however, many challenges remain. One challenge is that lab conditions differ from actual agricultural production conditions. Another challenge is that spectral data characteristics are not universally applicable to all situations. Therefore, in this study, the field test method was adopted to conduct experiments during the full growth period of wheat, and the spectrum data of wheat canopy were processed by the first derivative method to screen-sensitive spectral bands as the basis for the prediction model of the copper content in wheat. The results showed that the copper content increased with an increase in the soil copper content, and there were dissimilar subtle differences in the spectral reflectance of wheat canopy under different stressed soil copper concentrations; sensitive spectral indices and wavelengths were screened based on good correlation with the copper content in the wheat canopy. Different optimal predicting models in different periods were built and verified. The established linear regression models, which were based on NDVI/SIPI and W728, were the most suitable predicting models during the tillering stage with R2 = 0.669 and 0.818; Rg, W741, and multiple bands were the most suitable predicting models during the jointing stage with R2 = 0.548, 0.830, and 0.868; the optimal model during the heading stage was based on W480 (R2 = 0.625). This study demonstrated that the constructed models had good potential for estimating the copper content in wheat leaves during full growth periods, and this method had the potential to be applied to the actual agricultural production process.

Assessment of Heavy Metals’ Contamination of Soils and Vegetable from Farmlands on Selected Floodplains in Akure and Environs, Nigeria

Aim: Among other absorption pathways, heavy metals affect human health via their introduction into the diet through the soil-food chain. This study was carried out to determine the concentration of heavy metals in soils and plant’s part of Amaranthus hybridus from five farmlands on floodplains in Akure and environs.
 Study Design: Soil and A. hybridus samples were obtained from five farmlands for the assessment of their heavy metals’ content and pollution levels.
 Place and Duration of Study: The study (six months’ duration) was conducted at the Department of Chemistry, The Federal University of Technology, Akure, Ondo State, Nigeria.
 Methodology: The assessment involved the use of standard methods of analyses and an atomic absorption spectrophotometer. Mathematical expressions were employed for estimating the bioconcentration factor, geoaccumulation index, contamination factor and pollution load index. Statistical difference of the results was evaluated using One-Way Analysis of Variance.
 Results: The experimental results revealed that the farmlands’ soils belong to four textural classes in which their heavy metals’ contents are all below the maximum allowable concentrations provided in the considered regulatory guidelines for soil. Evaluation of the geoaccumulation index showed that concentration of all heavy metals in the soils are not enriched above the baseline concentration as most of the soils belong to Class 0 (uncontaminated category). Pollution load index estimated from the contamination factors also indicated no overall pollution of the farmlands. Uptake of the studied heavy metals by A. hybridus was at varied levels while vegetable samples from Ogbese farmland had the highest bioconcentration factor for copper, nickel and chromium.
 Conclusion: Although most of the farmland soils have satisfactory physicochemical properties and present safe level of the studied heavy metals, the research revealed the need for cultivation of vegetables which are extremely poor bioaccumulators of heavy metals in these farmlands.

Assessment of Spectroscopic and Morphological Properties of some Fruit Crops under the Influence of Pollution with Heavy Metals Using Remote Sensing Techniques

Dietary exposure to a variety of heavy metals, including Ni, Cd, Cr, Pb, Zn, and Hg, has been identified as a danger to human health through fruits and vegetables, contamination of heavy metals is known as a grave risk to our climate. The study aims to develop empirical models to predict the concentration of heavy metals (Ni, Cd, Cr, Pb, Zn, and Hg) in the leaves of Citrus and Mango crops. The study was carried out in an observation site in Giza governorate that is cultivated by varied herbaceous and tree cover crops. This study area is suffering from severe pollution caused by near industrial district. The sample collected from deferent zones that are divided to six spatial zones and coded by from zone (2, 3, 4, 5, and 6). The distance between each Zone 10 Km that extends from the north to south and covers 60% from the Agriculture area in the Giza governorate. The main inputs of the generated models were spectroscopic remotely sensed data and laboratory analytical measurements of heavy metals in crop leaves. ASD (Analytical Spectral Devices) field spectro-radiometer was used to calculate hyper-spectral vegetation indices. Modeled heavy metal concentrations were tested against laboratory analysis through two common statistical tests; the Correlation of determination (R2) and Root Mean square (RMSE) error between predicted modeled heavy metals. Results shown the correlation coefficient of the generated models, red and near-infrared spectral bands demonstrated high precision and sufficiency for mango and citrus leaves to predict heavy metals. The models produced refer to specific regions with the same conditions. The overall results imply that hyper-spectral vegetation indices could be correlated with heavy metal content, while heavy metal content in plants may be influenced by many others. Remote sensing spectroscopy is a possible and promising technology to track the environmental pressures on agricultural vegetation. Additional ground remote sensing experiments are needed to assess the possibility of hyper-spectral reflectance spectroscopy in monitoring the stress of different types of metals on various plants.

Heavy metals in the Arctic: Distribution and enrichment of five metals in Alaskan soils.

Metal contamination of food and water resources is a known public health issue in Arctic and sub-Arctic communities due to the proximity of many communities to mining and drilling sites. In addition, permafrost thaw may release heavy metals sequestered in previously frozen soils, potentially contaminating food and water resources by increasing the concentration of metals in freshwater, plants, and wildlife. Here we assess the enrichment of selected heavy metals in Alaskan soils by synthesizing publicly available data of soil metal concentrations. We analyzed data of soil concentrations of arsenic, chromium, mercury, nickel, and lead from over 1,000 samples available through the USGS Alaskan Geochemical Database to evaluate 1) the spatial distribution of sampling locations for soil metal analysis, 2) metal concentrations in soils from different land cover types and depths, and 3) the occurrence of soils in Alaska with elevated metal concentrations relative to other soils. We found substantial clustering of sample sites in the southwestern portion of Alaska in discontinuous and sporadic permafrost, while the continuous permafrost zone in Northern Alaska and the more populous Interior are severely understudied. Metal concentration varied by land cover type but lacked consistent patterns. Concentrations of chromium, mercury, and lead were higher in soils below 10 cm depth, however these deeper soils are under-sampled. Arsenic, chromium, mercury, nickel and lead concentrations exceeded average values for US soils by one standard deviation or more in 3.7% to 18.7% of the samples in this dataset. Our analysis highlights critical gaps that impede understanding of how heavy metals in thawing permafrost soils may become mobilized and increase exposure risk for Arctic communities.

Consumption of Raw Herbal Medicines Is Associated with Major Public Health Risks amongst Ugandans.

Background Community consumption of herbal plants in developing countries is a common practice, however, scarcity of information on their physiochemical composition is a major public health concern. In Uganda, Vernonia amygdalina is of interest in rural communities due to its therapeutical action on both bacterial and protozoal parasites, however no studies have been conducted to assess the heavy metal concentrations in traditional plants used in alternative medicine. The aim of the study was to establish concentrations of heavy metals in Vernonia amygdalina, model the estimated daily intake (EDI), and assess both the non-cancer-related health risk using the target hazard quotient (THQ), and the risk related to cancer through the incremental lifetime cancer risk (ILCR) for the Ugandan population. Methods Leaves of Vernonia amygdalina were collected from 20 georeferenced villages and processed into powder in the laboratory using standard methods. These were then analyzed in the laboratory using an atomic absorption spectrometer for lead (Pb), chromium (Cr), copper (Cu), zinc (Zn), cobalt (Co), iron (Fe), cadmium (Cd), and nickel (Ni). Concentrations were compared against the World Health Organization (WHO) limits. The EDI, THQ, and ILCR were modelled and significance was measured at 95% confidence. Results The study showed that mean ± SEM concentrations of heavy metals were highest in the order of Cr, 121.8 ± 4.291 ppm > Ni, 84.09 ± 2.725 ppm > Zn, 53.87 ± 2.277 ppm > Pb, 40.61 ± 3.891 ppm > Cu, 28.75 ± 2.202 ppm > Fe, 14.15 ± 0.7271 ppm > Co, 7.923 ± 0.7674 ppm > Cd, 0.1163 ± 0.005714 ppm. Concentrations of Pb, Cr, Zn, Co, and Ni were significantly higher than the WHO limits. The EDI was significantly higher in children than in adults, demonstrating an increased risk of toxicity in children. The THQ and ILCR were over 1000 times higher in all Ugandans, demonstrating the undesirable health risks following oral consumption of Vernonia amygdalina due to very high Cr and Ni toxicities, respectively. Conclusion Consumption of raw Vernonia amygdalina was associated with a high carcinogenic risk, demonstrating a need to enact policies to promote physiochemical screening of herbal medicines used in developing countries against toxic compounds.

Trace metal dynamics in soils and plants along intertidal gradients in semi-arid mangroves (New Caledonia)

Trace metal dynamics were investigated in mangroves developing in semi-arid New Caledonia, where Avicennia and Rhizophora stands grow in the upper and lower intertidal zone, respectively. We collected soil samples and mangrove tissues in an undisturbed site, a mining-influenced site and in a mining and aquaculture-influenced site. Differences in duration of immersion and organic matter (OM) cycling resulted in a sharp decrease of metal concentrations in soils and plants from landside to seaside. Both species were tolerant to metals mainly via exclusion, (i.e. metal bioaccumulation restricted to roots and leaf litter). Strong correlations (p < 0.05) were found between Na and Fe, Mn, Cu and Zn in green and senesced leaves of Avicennia marina, indicating a possible role of those metals in mechanisms to cope with hypersaline conditions.Increasing metal pollution, aridity and sea-level rise are likely to result in a decrease in mangrove efficiency in filtering trace metals seaward.

INITIAL SURVEY OF HEAVY METAL CONCENTRATIONS IN PADDY SOIL AND RICE PLANTS (Oryza sativa L.) NEAR AND FAR FROM OPEN LANDFILL IN SOUTHERN VIET NAM

The concentrations of heavy metals in soil and rice plants around the landfill area in Dong Thang commune, Co Do District, Can Tho City, Viet Nam needed to be assessed for environmental pollution. Soil samples were collected from four sites (three sites S1, S2, S3 near and one site S4 far away from the landfill area) at soil depths of 0 to 25 and 25 to 50 cm. The rice and soil samples were simultaneously collected at the same locations for analysis of heavy metals. The heavy metals Mn, Zn, Cu, Cr, Ni, Pb and Cd were analyzed using atomic absorption spectroscopy. Six heavy metals including Mn, Zn, Cu, Cr, Ni, and Pb were detected and ranged from 12.3 to 291.0 mg/L for the top soil and 11.2 to 370.0 mg/L for 25 to 50 cm soil layer. However, concentrations of Ni, Cu, and Pb in soil tended to decrease while Mn, Zn and Cr tended to increase with an increase of soil depth near the landfill. A similar tendency of heavy metal concentration with depth was found at S4 except for Cu. The decreasing order of the selected heavy metals concentrations in the two soil layers at near the landfill was Mn&gt;Zn&gt;Ni&gt;Cr&gt;Cu&gt;Pb and these concentrations of heavy metals were within the limits of QCVN 03-MT: 2015/BTNMT and Canadian Council of Ministers of the Environment (CCME, 2007). The result of the bioaccumulation factor (BAF) in rice plants showed that the selected heavy metals were accumulated more in the root rather than the stem-leaf and grain. Mn was accumulated dominantly in both root and stemleaf, while Zn, Cu, and Pb only accumulated in the root. Thus, result of this study suggests that is essential to collect and treat the heavy metals in the leachate properly to minimize the distribution of heavy metals to the paddy soil environment.

Responses of soil bacterial community and Cd phytoextraction to a Sedum alfredii-oilseed rape (Brassica napus L. and Brassica juncea L.) intercropping system

Soil pollution with heavy metals has become a common problem in agricultural ecosystems and poses a threat to food safety and human health. Intercropping is now considered a promising alternative to address this issue. However, our understandings about the influences of intercropping systems on rhizosphere microbiota composition and their association with plant performance are still limited. In this study, rhizobox microcosm experiments were conducted to investigate the influence of cropping regimes (i.e. monoculture and intercropping) on the rhizosphere bacterial microbiota and their linkages with the phytoextraction of cadmium (Cd) by Zhongyouza 19 (Brassica napus L.), Xikou Huazi (Brassica juncea L.) and Sedum alfredii using 16S rRNA gene sequencing. Cadmium accumulation in shoots of B. napus and B. juncea grown under intercropping were enhanced by 370% and 27.8% respectively, as compared to monoculture. Soil compartmentation as a major determinant explained 57.6% of the rhizosphere bacterial microbiota variation, whereas plant species and cropping regime accounted for 26.4% of the variation. The overall abundance of the taxa was Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Verrucomicrobia, and Actinobacteria. Intercropping significantly enriched amplicon sequence variants (ASVs) abundance belonging to Actinobacteria, Bacilli, Deltaproteobacteria while depleting that of Acidobacteria in rhizosphere. Intercropping with S. alfredii influenced more on microbial composition of B. napus rhizosphere. The change in rhizosphere bacterial communities was related to metal availability, soil properties, and plant parameters. The enriched families of Pedosphaeraceae, Ruminococcaceae, Chitinophagaceae, Gemmatimonadaceae, Nitrosomonadaceae, and Parachlamydiaceae were positively correlated with metal concentration in plants. These results indicate that S. alfredii and oilseed rape intercropping could be a promising approach for enhancing the remediation of Cd contaminated soil. Understanding the complex plant-microbe-metal interactions of intercropping system could facilitate the development of remediation strategy for phytoremediation of contaminated soils and sustainable agricultural production.

Evaluation of Contamination and Ecological Risk of Heavy Metals Associated with Cement Production in Ewekoro, Southwest Nigeria.

Background.Exposure to heavy metals emanating from cement production and other anthropogenic activities can pose ecological risks.Objectives.A detailed investigation was carried out to assess the contamination and ecological risk of heavy metals associated with dust released during cement production.Methods.Sixty samples, including 30 soils and 30 plants, were collected around Lafarge Cement Production Company. Control samples of soil and plants were collected in areas where human activities are limited. Samples were dried, sieved (for soil; 65 μm), packaged and analyzed using inductively coupled plasma mass spectrometry at Acme Laboratory in Canada.Results.The average concentration of heavy metals in soils of the area are: copper (Cu): 41.63 mg/kg; lead (Pb): 35.43 mg/kg; zinc (Zn): 213.64 mg/kg; chromium (Cr): 35.60 mg/kg; cobalt (Co): 3.84 mg/kg and nickel (Ni): 5.13 mg/kg. Concentrations of Cr in soils were above the recommended standards, while other metals were below recommended limits. The average concentrations of heavy metals in plants were: Cu: 26.32 mg/kg; Pb: 15.46 mg/kg; Zn: 213.94 mg/kg; Cr: 30.62 mg/kg; Co: 0.45 mg/kg and Ni: 3.77 mg/kg. Levels of heavy metals in plants were all above international limits. Geo-accumulation of metals in soils ranged between −0.15 and 6.32, while the contamination factor ranged between 0.53 and 119.59. Ecological risk index of heavy metals in soils ranged between 49.71 and 749.Discussion.All metals in soils of the study area except for Cr were below the allowable limits, while the levels of metals in plants were above the permissible limits. Levels of heavy metals reported in this study were higher than those from similar cement production areas. Soils around the Ewekoro cement production area were low to extremely contaminated by toxic metals. Cement production, processing, transportation in conjunction with the abandoned railway track in the area greatly contribute to the high degree of contamination observed in the area. Metal transfers from soil to plant are a common phenomenon. The metals pose low to considerable ecological risk.Conclusions.Anthropogenic sources, especially cement processing activities, release heavy metals which leads to progressive pollution of the environment and poses high ecological risk.Competing Interests.The authors declare no competing financial interests

Prediction models for monitoring heavy-metal accumulation by wheat (Triticum aestivum L.) plants grown in sewage sludge amended soil

Prediction of heavy-metal concentration in the edible parts of economic crops, based on their concentration in soil and other environmental factors, is urgently required for human risk assessment. The present investigation aimed to develop regression models for predicting heavy-metal concentration in wheat plants via their contents in sewage sludge amended soil, organic matter (OM) content and soil pH. The concentration of heavy metals in the plant tissues reflected its concentration in the soil with high Fe followed by Al, Mn, Cr, Zn, Ni, Co, Cu, and Pb. Soil OM content had a significant positive correlation with all investigated heavy-metal concentrations in the different tissues of wheat plants, while soil pH was negatively significant with most heavy metals except spike Pb and grain Cr. The bio-concentration factor of Al, Cu, and Zn from soil to wheat root was >1, while that of shoot, spikes, and grains was <1 for all heavy metals. Significantly valid regression models were developed with fluctuated coefficient of determination (R2), high model efficiency (ME) values and low mean normalized average error (MNAE). The significant positive correlations between the concentration of some heavy metals in the soil and the same in wheat tissues indicate the potential of this plant as a biomonitor for these metals in contaminated soils. The significant correlations between heavy-metal concentrations in soil and its properties (pH and OM) with metal concentrations in wheat plants support the prediction model as an appropriate option. This study recommends the use of models with R2 greater than 50% and recommend other researchers to use our models according to their own specific conditions.

Heavy metal concentrations in roadside plants (Achillea wilhelmsii and Cardaria draba) and soils along some highways in Hamedan, west of Iran.

The present study was conducted to analyze the effects of traffic volumes on Cd, Cu, Pb, Ni, and Zn contents in roadside soils and in two dominant herbaceous species (Achillea wilhelmsii and Cardaria draba) along highways and to evaluate the dynamic characteristics of these elements and their accumulation by the aerial parts and roots of these herbaceous species. The plant samples were collected along 700m of a 9-km segment of each of the three major highways in Hamedan Province (West Iran) with different traffic volumes: Hamedan-Goltapeh (HG), Hamedan-Razan (HR), and Hamedan-Kermanshah (HK). The results indicated that the mean contents of Cd, Cu, Pb, Ni, and Zn in the soil samples were 0.26, 18.74, 14.98, 18.21, and 62.25mgkg-1, respectively. Furthermore, the mean contents of elements (mgkg-1) in aerial parts of A. wilhelmsii were 0.16 for Cd, 4.52 for Cu, 1.91 for Pb, 1.70 for Ni, and 44.80 for Zn, while in the aerial part samples of C. draba, the concentrations (mgkg-1) and the mean contents were 0.16, 2.29, 2.58, 1.60, and 31.29, respectively. This meant that the traffic volume affected the contents of the metals in the soil and the herbaceous species. The metal content in herbaceous tissues varied significantly between plant species. A. wilhelmsii tended to accumulate the metals in the roots while C. draba retained them mostly in the aerial parts. The significant positive correlations of Cd, Cu, Ni, and Zn content in root and aerial parts of the herbaceous plant with those found in the soil samples showed the potential of the studied species for application in biomonitoring studies. Comprehensive analysis (effect of traffic volumes and relationships between the content of elements in plant tissues and soil samples) indicated that Cu in both herbaceous plants was mainly derived from soil, while A. wilhelmsii absorbed Cd and C. draba absorbed Zn mainly through the stomata from atmospheric depositions. Without considering atmospheric depositions due to intense traffic volumes, in A. wilhelmsii, the translocation factor (TF) values of Cu and Zn were 1.06 and 1.44, respectively and in C. draba, the TF values of Cd, Cu, and Pb were 1.06, 1.09, and 1.13, respectively, thus suggesting that both herbaceous species had high potentials for transferring metals from the roots to aerial parts.

Combined cadmium-zinc interactions alter manganese, lead, copper uptake by Melissa officinalis

Farmland soil typical for the Polish rural environment was used in pot experiment to estimate the impact of cadmium and zinc on the manganese, lead and copper uptake by lemon balm (Melissa officinalis L). Bioavailable and total forms of investigated metals in soil and metal concentrations in plants were determined by atomic absorption spectrometry. The plant photosynthesis indicators were also examined. Intensification of photosynthesis upon the high zinc and cadmium soil supplementation was observed. This effect was not detected at low metal concentrations. ANOVA proved that cadmium and zinc treatments influenced manganese, lead and copper transfer from soil and their concentration in plants. Zinc uptake and accumulation in either roots or above-ground parts in plant was inversely proportional to cadmium concentration in soil. Manganese concentration in roots decreased upon the soil supplementation with either zinc or cadmium. It suggests that the latter ions are transported via symplastic pathways and compete with manganese for similar transporters. The opposite situation was observed for lead and copper. Soil supplementation with cadmium and zinc affects manganese, lead and copper concentrations and photosynthesis intensity in lemon balm plant. The following combined interactions in either normal or stress conditions are important indicators of the migration pathways.

Biochar Facilitated Hydroxyapatite/Calcium Silicate Hydrate for Remediation of Heavy Metals Contaminated Soils

High levels of heavy metals in soil pose considerable threats to the ecosystem. The in situ remediation technology is obtaining increasing global concerns as a sustainable remediation strategy. In this study, the hydroxyapatite/calcium silicate hydrate (HAP/CSH) was recovered from waste water to evaluate the effects on heavy metal immobilization by coupling with biochar. Five mixtures of HAP/CSH and biochar with different weight ratios (10:0, 0:10, 1:9, 2:8, 4:6 w/w) were prepared to remediate two heavy metal–contaminated soils planted with water spinach (Ipomoea aquatica Forsk.). The mixture of HAP/CSH and biochar in the ratio of 4:6 shows the best immobilization effect assessed by toxicity characteristic extraction procedure (TCLP) and BCR sequence extraction procedure. After remediation, the immobilization efficiency decreased 83%, and content of heavy metals in plants decreased 72.8%. The conversion efficiency of heavy metal residual fraction was 3.95 times higher than that of the control group. At the same time, soil pH, water-soluble organic carbon (WSOC), and soil microbial biomass (SMB) all showed an increasing trend, indicating the improvement of soil conditions. The combined application of HAP/C-S-H and biochar changed soil bacterial community structure, leading to an increase in soil bacterial diversity. The results of redundancy analysis (RDA) suggested that pH and the concentration of heavy metals were the main factors affecting microbial community. Therefore, the mixture of HAP/C-S-H and biochar can be considered as an effective, feasible, and environmentally friendly amendment for the remediation of Cd-contaminated soil and multi-metal–contaminated soil.

Exploring the phytoremediation potential of Cynara cardunculus: a trial on an industrial soil highly contaminated by heavy metals.

Metal uptake capacity and growth patterns of three cardoon cultivars (Sardo, Siciliano, and Spagnolo) were investigated for phytoremediation in a metal-contaminated soil. Metal concentrations after one and two growth rounds were measured in soil and plants by ICP-MS. Potentially and promptly available metal fractions were estimated by EDTA and ammonium nitrate. Plant weight, water and nitrogen content, and life span were considered as growth parameters. After the first growth cycle, a significant accumulation of all elements was observed in roots, whereas only Cd, Cu, Fe, Pb, and Sb were significantly translocated to the shoots. After the second growth cycle, a further significant increase, especially in roots, was observed in all cultivars and for all elements considered. High percentages of the potentially available fraction were found for As, Cd, Cu, Pb, and Sb. Metal concentrations in plants were far higher than the promptly available fraction, indicating an increase of metal bioavailability during culture rounds. A severe decrease of weight and life span was observed in Sardo and Siciliano grown on polluted soil, along with an increase in N content. The cultivar Spagnolo, harmonizing a high ability of metal uptake and tolerance, proved the most efficient cultivar in metal phytoremediation.

Bioaccumulation of Trace Metals in Plants Grown in Sewage Sludge Amended Soil

A survey was established to study the mobility of metals (Cr, Mo, Cu, and Zn) from soils amended with municipal sewage sludge (SS) into plants grown at three locations in Kentucky and compare metal concentrations in plants to their permissible standard limits. The field experiments were established at Meade, Adair, and Franklin Counties in Kentucky areas where commercial growers use SS as alternative to inorganic fertilizers. Metals in soil and plant tissue were quantified using Inductively Coupled Plasma (ICP) spectrometer. Results revealed that different trace metals had different uptake pattern by different plants. Cr concentrations in beans has shown very little accumulation in bean seeds. Cr and Mo concentrations in plants grown at the three locations were below the permissible level of 1.3 µg g^-1 tissue. Other than onion bulbs, Cu concentrations were above the permissible level of 10 µg g^-1 tissue in plants grown at Meade site. At the Adair site, Cu was above the limit only in tobacco leaves. Whereas at Franklin site, Cu was above the limit in potato tubers, onion bulbs, and tomato fruits. Zn concentration in all plants tested never exceeded the permissible level of 0.6 µg g^-1 tissue.

Transfer factor as indicator of heavy metal content in plants around adipala steam power plant

The purpose of this research is to identify and characterize the main and trace metals in plant (cassava leaves and grass) and soil. Results of the characterization was used to determine the transfer factor (TF) of metal absorption from soil to plant around Adipala power plant located in Cilacap Regency. Measurement of metal concentrations were carried out using instrumental neutron activation analysis techniques. Samples were irradiated in Rabbit and Lazy Susan system facility at the Kartini research reactor located in Centre for Accelerator Science and Technology. Irradiated samples then counted using HPGe detector. Concentration values for heavy metals were below the maximum recommended value stated by WHO and FAO. Transfer factor (TF) is used to assess the concentration of metals in cassava leaves and grass taken from soil. The TF value calculated in this research were below 1, this implied that cassava leaves and grass were safe from the risk of heavy metals. The highest transfer factor value is Sb, it showed that is Sb was more mobile compare to other metals.

Determine heavy metals in water, aquatic plants, and sediment in water systems

Objective:Biomonitoring pollution of water bodies with heavy metals using evaluation of the level of concentration of heavy metals in water, aquatic plants, and sediments in 9 important rivers and lakes in the water bodies of Yekaterinburg. (Eight rivers and one lake).Methods: Sample preparation for the atomic absorption determination of the acid-soluble “mobile” form of eight metals (Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) in the composition of bottom sediments was carried out by the method of wet mineralization in accordance with the Methodological Guidelines the definition of heavy metals.Results:All concentrations of heavy metals in sediments and aquatic plants were higher than in a water sample.Conclusions: Concentrations of all water samples were within acceptable limits established by WHO, while the concentrations of all aquatic plants and sediment were above the acceptable limits of WHO.