Regression models for monitoring trace metal accumulations by Faba sativa Bernh. plants grown in soils amended with different rates of sewage sludge

Impact of brewery sludge application on heavy metal build-up, translocation, growth and yield of bread wheat (Triticum aestivum L.) crop in Northern Ethiopia

In a field study, the impact of different levels of brewery sludge (BS) enrichment on Triticum aestivum L. (wheat plants) was examined in terms of growth, yield, heavy metal absorption, and potential health risks linked to plant consumption. Using a randomized complete block design with seven treatments and three blocks, the study showed that applying up to 12 t ha-1 brewery sludge significantly improved all agronomic parameters (except harvest index) compared to control and mineral-fertilized soil. Heavy metal translocation was generally low, except for Cu and Pb. The sequence of heavy metal translocation was Cu > Pb > Cd > Ni > Zn > Mn > Cr from soil to spikes and Cu > Zn > Mn > Pb > Ni > Cd > Cr from soil to grain. Heavy metal loads were mostly higher in roots than in the above-ground crop parts. The target hazard quotient (THQ), hazard index (HI), and target cancer risk (TCR) within wheat grain remained within safe limits for all BS treatments. Consequently, consuming this wheat grain is considered safe regarding heavy metals. Thus, utilizing brewery sludge at 12 t ha-1 as a fertilizer for wheat production and as an alternative method for sludge disposal is plausible.

An experimental and prediction modeling study on water lettuce (Pistia stratiotes L.) assisted heavy metals removal from glass industry effluent

The glass manufacturing industry produces hazardous effluent that is difficult to manage and causes numerous environmental problems when disposed of in the open. In this study, an attempt was made to study the phytoremediation feasibility of water lettuce (Pistia stratiotes L.), a free-floating aquatic macrophyte, for the removal of six heavy metals from glass industry effluent (GIE) at varying concentrations (0, 25, 50, 75, and 100%). After a 40-day experiment, the results showed that 25% GIE dilution showed maximum removal of heavy metals i.e., Cu (91.74%), Cr (95.29%), Fe (86.47%), Mn (92.95%), Pb (87.10%), and Zn (91.34%), respectively. The bioaccumulation, translocation, and Pearson correlation studies showed that the amount of heavy metals absorbed by vegetative parts of P. stratiotes was significantly correlated with concentrations. The highest biomass production, chlorophyll content, relative growth rate, and biomass productivity were also noted in the 25% GIE treatment. Moreover, the multiple linear regression models developed for the prediction of heavy metal uptake by P. stratiotes also showed good performance in determining the impact of GIE properties. The models showed a high coefficient of determination (R2 > 0.99), low mean average normalizing error (MANE = 0.01), and high model efficiency (ME > 0.99) supporting the robustness of the developed equations. This study outlined an efficient method for the biological treatment of GIE using P. stratiotes to reduce risks associated with its unsafe disposal.

Teíchophoresis-enabled electrokinetic sample preparation and detection of calcium in natural plant samples

We present a novel upstream electrokinetic sample preparation and liquid interfacial microfluidic method to pre-concentrate, detect and quantify the concentration of a charged species, such as calcium, from a natural plant sample. We employ a new electrokinetic phenomenon, termed as "Teíchophoresis" (TPE) to preconcentrate sample calcium ions (up to a 20X increase) against a conductive wall. Using microfluidic flow, we then continuously transport the pre-concentrated calcium to a hydrodynamically streamed interfacial sensing zone where we utilize the model fluorescent chelation reaction between calcium and Calcium Green-1 (CG1) to fluorescently quantify the calcium concentration. Using a combination of finite element analysis and finite difference numerical modelling, we model the kinetics of the CG1-calcium interfacial binding and predictably validate our TPE-driven concentration results. Finally, we demonstrate the applicability of our device for real world samples by determining the calcium concentration in a tree bark extract acquired from a southern live oak and confirm our concentration results using ICP-MS.

Biosolids application enhances the growth of Aloe vera plants and provides a sustainable practice for nutrient recirculation in agricultural soils

In the present study, the fertilization potential of biosolids (sewage sludge; SS) for the cultivation of Aloe vera plants was investigated using block design. Pot experiments were conducted in this study using 50, 100, 150, and 200 g/kg of SS. Results showed that SS-fertilized soils significantly (p < 0.05) affected the proximate, biochemical, and heavy metal parameters of A. vera plants. In particular, the T4 treatment gave the best results with maximum plant height 62.21 ± 0.10 cm, number of leaves per plant 18.00 ± 4.00, shoot-to-root ratio 6:1, fresh weight 1972.10 ± 0.07 g per plant, dry weight 175.49 ± 0.15 g per plant, total chlorophyll content (TCC) 0.41 ± 0.02 mg/g fwt., carotenoids 0.25 ± 0.04 mg/g, total flavonoids 7.55 ± 0.05 mg/g, total tannins 3.87 ± 0.06 µg/g, ascorbic acid 532.14 ± 0.10 µg/g, superoxide dismutase (SOD) 46.28 ± 0.19 µg/g, catalase (CAT) 119.23 ± 0.17 µg/g, salicylic acid 3.05 ± 0.12 mg/ml and anthraquinones 0.45 ± 0.04 mg/ml, respectively. The proximate plant characteristics were 96.25 ± 2.71% moisture content, crude protein 0.93 ± 0.05%, crude fiber 5.78 ± 0.44%, crude lipid 3.25 ± 0.02%, lignin 10.74 ± 0.30%, cellulose 13.56 ± 1.06%, hemicellulose 7.24 ± 0.14%, ash 8.75 ± 0.03%, and carbohydrate contents 52.18 ± 1.10% in comparison with control treatment. The bioaccumulation factor showed that heavy metal accumulation was in the order of Cd < Ni < Cu < Pb < Cr < Zn < Fe. The prediction models developed on the basis of soil properties showed good fitness results for the prediction of heavy metal uptake by A. vera plants. The study presented a sustainable approach for managing SS in an eco-friendly way while producing good-quality A. vera plants.

Effect of composite amendments on physicochemical properties of copper tailings repaired by herbaceous plants

Phytoremediation is considered to be the most environmentally friendly green restoration technology for dealing with mine waste. Adding amendments can improve the substrate environment for plant growth and enhance remediation efficiency. Herbaceous plants have become the preferred species for vegetation restoration in abandoned mines because of their fast greening and simple management. After 8 weeks of pot experiments in the early stage, it was shown that the plant height and fresh weight of the plants treated with 5% conditioner and 0.5% straw (C₂S₂) were significantly higher than those of other treatments. Considering that, in this paper, to explore the effect of composite amendments on physicochemical properties of copper tailings repaired by herbaceous plants, the untreated copper tailings were employed as the control group, whereas copper tailings repaired by ryegrass (Lolium perenne L.), vetiver grass (Chrysopogon zizanioides L.), and tall fescue (Festuca arundinacea) with or without conditioners and straw combination into the compound amendments were taken separately as the test group. After 6 months of planting, the pH, electrical conductivity, water content, available potassium, organic matter, total nitrogen, and available phosphorus in the main physical and chemical properties of copper tailings in each experimental area were analyzed. The results showed that the electrical conductivity, organic matter, and total nitrogen content of copper tailings were improved to a certain extent by planting plants without treatment. Meanwhile, compared with the control group, all indexes of planting plants showed an upward trend after adding composite amendments. Among them, pH, water content, and available potassium content of copper tailings were enhanced more obviously. Furthermore, as discovered from the gray correlation analysis results, vetiver grass planted with composite amendments has the best comprehensive effect of improving the physicochemical properties of copper tailings, followed by tall fescue and ryegrass.

Safety assessment and sustainability of consuming eggplant (Solanum melongena L.) grown in wastewater-contaminated agricultural soils

Vegetables cultivated on contaminated agricultural soils are being consumed by the public, and consequently cause serious health concerns due to contaminants' dietary intake. The current study examines the safety and sustainability of eating eggplant (Solanum melongena) by looking into the possibility of heavy metals translocation from polluted soils to the edible sections, as well as the health hazards that come with it. Soil and eggplant samples were taken from three contaminated and other three uncontaminated farms to estimate their chemical constituents and plant growth properties. Based on the pollution load index data, the contaminated soils were highly polluted with Fe, Cu, Pb, and Zn; and relatively polluted with Cr, Mn, Cd, Mn, Co, and V. Under contamination stress, the fresh biomass, dry biomass, and production of eggplant were significantly reduced by 41.2, 44.6, and 52.1%, respectively. Likewise, chlorophyll a and b were significantly reduced from 1.51 to 0.69 mg g⁻¹ and 1.36 to 0.64 mg g⁻¹, respectively. The uncontaminated plant shoots had the highest quantities of N, P, and proteins (1.98, 2.08, and 12.40%, respectively), while the roots of the same plants had the highest K content (44.70 mg kg⁻¹). Because eggplant maintained most tested heavy elements (excluding Zn and Pb) in the root, it is a good candidate for these metals' phytostabilization. However, it had the potential to translocate Mn and Zn to its shoot and Pb, Cr, Mn, and Zn to the edible fruits indicating its possibility to be a phytoextractor and accumulator of these metals. Cd, Cu, Ni, Pb, Mn, and Co quantity in the edible sections of eggplant grown in contaminated soils exceeded the permissible level for normal plants, posing health hazards to adults and children. For safety issues and food sustainability, our investigation strongly recommends avoiding, possibly, the cultivation of eggplant in contaminated agricultural lands due to their toxic effects even in the long run.

Effects of sewage sludge pretreatment methods on its use in agricultural applications

Pretreatment is widely used in sludge dewatering, however, its potentially impact on the subsequent sludge agricultural applications is often neglected. Here, the potential benefits and risks of the sludge with no pretreatment and with four most commonly used pretreatment methods in sludge agricultural applications were assessed using potted lettuce, an experimental crop. The results show that sewage sludge pretreatment methods can greatly affect its agricultural applications. The application of different pretreatment methods can potentially reduce the harm caused by pathogens. At low dosage (0.2 g kg^-1), different sludge fertilizers promoted an increase in crop yield of 14.6% to 49.1%, and the concentrations of heavy metals in the crop and soil were controlled within safe ranges. At high dosage (8 g kg^-1), crop yield using pretreated sludge (except anaerobic digestion) decreased by between 32.7% and 57.5%, but heavy metal pollution of both crop and soil increased. In terms of promoting crop growth and reducing heavy metal accumulation, untreated sludge was better than pretreated sludges and sludge with physical pretreatments was better than that with chemical pretreatments. Overall, this study clearly shows that the introduction of pretreatment in sludge dewatering can inevitably impact its agricultural land application.

Metal Tolerance Protein Encoding Gene Family in Fagopyrum tartaricum: Genome-Wide Identification, Characterization and Expression under Multiple Metal Stresses

Metal tolerance proteins (MTP) as divalent cation transporters are essential for plant metal tolerance and homeostasis. However, the characterization and the definitive phylogeny of the MTP gene family in Fagopyrum tartaricum, and their roles in response to metal stress are still unknown. In the present study, MTP genes in Fagopyrum tartaricum were identified, and their phylogenetic relationships, structural characteristics, physicochemical parameters, as well as expression profiles under five metal stresses including Fe, Mn, Cu, Zn, and Cd were also investigated. Phylogenetic relationship analysis showed that 12 Fagopyrum tartaricum MTP genes were classified into three major clusters and seven groups. All FtMTPs had typical structural features of the MTP gene family and were predicted to be located in the cell vacuole. The upstream region of FtMTPs contained abundant cis-acting elements, implying their functions in development progress and stress response. Tissue-specific expression analysis results indicated the regulation of FtMTPs in the growth and development of Fagopyrum tataricum. Besides, the expression of most FtMTP genes could be induced by multiple metals and showed different expression patterns under at least two metal stresses. These findings provide useful information for the research of the metal tolerance mechanism and genetic improvement of Fagopyrum tataricum.

Prediction models based on soil properties for evaluating the heavy metal uptake into Hordeum vulgare L. grown in agricultural soils amended with different rates of sewage sludge

The current study aims at forming new prediction models to be employed in the approximating the possible uptake of a range of 10 heavy metals (HMs) (Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) by Hordeum vulgare tissues including roots, shoots and grains following its growth in soil amended with sewage sludge (SS) using conditions employed in greenhouses. The present study determined an insignificant difference between the actual and predicted quantities of the HMs in the three tissues using t values. The majority of the predicted quantities of the HMs were acceptable with the exception of Cd in the shoots, Cu in grains and Pb in roots. Consequently, it is possible to use these models in assessing the cultivation of barley plants in soil amended with SS in a safe way, while simultaneously monitoring any potential risks to the health of humans.

Variation of soil properties with sampling depth in two different light-textured soils after repeated applications of urban sewage sludge

Semi-arid agricultural soils have increasingly been subjected to urban sewage sludge (USS) applications due to accelerated soil depletion and shortages in manure supply. Research studies addressing USS reuse have mostly been conducted in cropping systems and focused on changes in topsoil properties of a given texture. Therefore, sludge-soil interactions could be largely influenced by the presence of plants, soil particle composition and depth. In this field study, two agricultural soils (sandy, S and sandy loam, SL) received simultaneously four annual USS applications of 40, 80, and 120 t ha^-1 year^-1 in absence of vegetation. Outcomes showed the increase of carbon and macronutrients in both soils proportionally to USS dose especially in the topsoil profile (0-20 cm). Subsoil (20-40 cm) was similarly influenced by sludge rates, showing comparable variations of fertility parameters though at significant lower levels. The depth-dependent improvement of soil fertility in both layers enhanced the microbiological properties accordingly, with significant variations in soil SL characterized by a higher clay content than soil S. Besides, positive correlations between increases in sludge dose, salinity, trace metals, and enzyme activities in both soils indicate that excessive sludge doses did not cause soil degradation or biotoxic effects under the described experimental conditions. In particular and despite high geoaccumulation indices of Ni in both soils and profiles, the global concentrations of Cu, Ni, Pb, and Zn were still below threshold levels for contaminated soils. In addition, the maintenance of pH values within neutral range and the increase of organic matter content with respect to control would have further reduced metal availability in amended soils. Therefore, we could closely investigate the effects of texture and depth on the intrinsic resilience of each soil to cope with repetitive USS applications.

Health assessment of medicinal herbs, celery and parsley related to cadmium soil pollution-potentially toxic elements (PTEs) accumulation, tolerance capacity and antioxidative response

Celery and parsley are recognized as medicinal herbs and nutraceutical vegetables due to their valuable pharmacological properties and numerous health benefits. However, in recent years, soil loadings with various PTEs have become a serious concern across the world, leading to plants pollution, which can consequently diminish their quality and safety for human consumption. Therefore, we attempted to quantify quality and safety of celery and parsley grown in Cd polluted soil. We examined the presence of PTEs: As, Cu, Fe, Mn, Ni, Cu and Cd in soil and selected herbs, as well as their physiological responses to different Cd exposures (control-without Cd addition, 3 and 6 µg/g Cd of dry soil). Following elevation of Cd in plants, both species showed increasing trend of As, Pb and Cu in plants, which overcome safe limits, with exception for Cu. Further, celery showed strong phytoextraction ability (99.9 µg/g Cd of dry weight) with high potential to tolerate Cd due to the efficient antioxidative machinery. Besides that herbs pollution was evident on the basis of target hazard quotients (HQ), hazard index (HI) and cancerogenic risk (CR), revealing that chronic consumption of contaminated herbs can consequently endanger human health. HI was greater than 1, while CR exceeded safe limits in treated plants, with exception for As. In the point of view of toxicology and food safety, growing of medicinal plants should be strictly regulated and distinguished based on the purpose of growing, and further herbs usage.

Analysis of the soil to food crops transfer factor and risk assessment of multi-elements at the suburban area of Ho Chi Minh city, Vietnam using instrumental neutron activation analysis (INAA)

The contamination of heavy metals in agricultural ecosystem is one of the most important problems in developing countries as Vietnam. In this study, we investigated the multi-element concentrations in soil, vegetables, soil-to-plant transfer factors and target hazard quotient (THQ) due to the consumption of heavy metals in Ho Chi Minh City, Vietnam. In general, the element concentrations in soil and plants were similar to different studies in the world and in the range of allowable values provided by WHO and the Ministry of Health of Vietnam. The transfer factors indicated the influence of element characteristics and plant genotypes on the accumulation and translocation of elements from soil to plants. It is found that I. batatas, B. alba, A, tricolor, O. basilicum, and B. juncea could be potential candidates for phytoremediation in soil contaminated of heavy metals. The results of individual and total THQ were below unity for Cr, Mn, Fe, Co, Zn, As, and Sb. The total THQ is in the range from 0.11 for R. sativus to 0.84 for B. alba with the average value of 0.43, in which Mn and As are the major contributions to the total THQ with the average values of 75% and 18%, respectively. The safety assessment based on national regulations and THQ indicated that the consumption of investigated vegetables poses no risk to the consumers.

Evaluation of uptake of eight metals by Sorghum bicolor grown in arable soil combined with sewage sludge based on prediction models

Prediction models were developed to estimate the extent to which aluminium, chromium, copper, iron, manganese, nickel, lead, and zinc were absorbed in the grains, leaves, stems, and roots of Sorghum bicolor cultivated in soil with various amendment rate of sewage sludge (0, 10, 20, 30, 40, and 50 g/kg) under greenhouse conditions. It was found that, aside from lead, all the examined metals occurred in significantly higher content in the roots compared to aerial tissues. Furthermore, the r-values were significantly negative between the bioconcentration factors of all metals, apart from aluminium and lead, and soil pH, whereas they were significantly positive between the bioconcentration factors, apart from lead, and soil organic matter content (OM). The r-values were typically significantly positive between the levels of all eight metals in the investigated tissues and in the soil. Moreover, the content of all the eight metals in the tissues exhibited a significant negative r-value with soil pH but a significant positive r-value with soil OM. The eight metal contents in the tissues given by the prediction models were quite similar to the real values, suggesting that the created models performed well, as shown by t-tests. It was thus concluded that prediction models were a viable option for evaluating how safe it was to grow S. bicolor in soils with sewage sludge content and at the same time for keeping track of possible human health hazards.

Heavy metals uptake by the global economic crop (Pisum sativum L.) grown in contaminated soils and its associated health risks

The aim of the present investigation was to determine the concentration of heavy metals in the different organs of Pisum sativum L. (garden pea) grown in contaminated soils in comparison to nonpolluted soils in the South Cairo and Giza provinces, Egypt, and their effect on consumers' health. To collect soil and plant samples from two nonpolluted and two polluted farms, five quadrats, each of 1 m2, were collected per each farm and used for growth measurement and chemical analysis. The daily intake of metals (DIM) and its associated health risks (health risk index (HRI) were also assessed. The investigated heavy metals were cadmium (Cd), arsenic (As), chromium (Cr), copper (Cu), nickel (Ni), iron (Fe), manganese (Mn), zinc (Zn), silver (Ag), cobalt (Co) and vanadium (V). Significant differences in soil heavy metals, except As, between nonpolluted and polluted sites were recorded. Fresh and dry phytomass, photosynthetic pigments, fruit production, and organic and inorganic nutrients were reduced in the polluted sites, where there was a high concentration of heavy metals in the fruit. The bioaccumulation factor for all studied heavy metals exceeded 1 in the polluted sites and only Pb, Cu and Mn exceeded 1 in the nonpolluted sites. Except for Fe, the DIM of the studied heavy metals in both sites did not exceed 1 in either children or adults. However, the HRI of Pb, Cd, Fe, and Mn in the polluted plants and Pb in the nonpolluted ones exceeded 1, indicating significant potential health risks to consumers. The authors recommend not to eat garden peas grown in the polluted sites, and farmers should carefully grow heavy metals non-accumulating food crops or non-edible plants for other purposes such as animal forages.

Use of sugar mill wastewater for Agaricus bisporus cultivation: prediction models for trace metal uptake and health risk assessment

This study explored the sustainable use of treated sugar mill wastewater (SMW) to cultivate the White button (Agaricus bisporus J.E. Lange) mushroom and the attendant risk of trace metals accumulated in the fruiting bodies. The wheat straw substrate was loaded with a normal water supply and different doses of SMW to enhance its moisture and nutrient contents. The impact of the SMW amendment on A. bisporus yield, biological efficiency, and spawn-running time was assessed. Furthermore, the substrate properties (pH, organic matter, total nitrogen, total phosphorus, etc.) based prediction models for trace metal uptake by A. bisporus fruiting bodies were developed using multiple linear regression (MLR) and artificial neural network (ANN) approaches. The results showed that maximum A. bisporus yield (158.42 ± 8.74 g/kg fresh substrate), biological efficiency (105.61 ± 3.97%), and minimum time of spawn-running (15 days) were observed in 75% SMW enrichment. For the prediction of Cd, Cu, Cr, Fe, Mn, and Zn trace metal uptake, the ANN models showed better performance in terms of R² (> 0.995), root means square error (RMSE < 0.075), model efficiency (ME > 0.99), and model normalized bias (MNB < 0.009), as compared with those of MLR models with R² (0.972), RMSE (< 0.441), ME (> 0.96), and MNB (< 0.034), respectively. On the other hand, the target hazard quotient (THQ) showed no significant health risk associated with the consumption of trace metal-contaminated A. bisporus in both adult and child groups. Thus, the findings of this study present a novel, safe, and sustainable method of A. bisporus cultivation along with treated agro-based wastewater management.

Mathematical Model to Simulate the Transfer of Heavy Metals from Soil to Plant

Heavy metals are naturally occurring elements, but their various applications have led to their wide circulation in the environment, raising concerns over their latent effects on the environment and human health. Their toxicity depends on numerous factors, including chemical species, concentration of heavy metal ions, environmental factors, etc. Experimental studies on the single or cumulative effects of heavy metals on plants are complex, time consuming and difficult to conduct. An alternative is mathematical modeling, which can include different factors into an integrated system and can predict plant and environmental behavior under multiple stressors. This paper presents a mathematical model that simulates the dependence of temperature, concentration of Zn in the soil and the subsequent bioaccumulation in lettuce (Lactuca sativa L.); respectively, the reaction of lettuce to Zn contamination. The main results consist of three mathematical models, based on systems of ordinary differential equations and checking their predictions with available experimental data. The models are applied to predict an optimal harvest time of lettuce with low concentration of Zn, in identifying the availability of the analyzed species to phytoremediation operations and the possibility of maneuvering certain control factors to reduce or increase the intensity of the bioaccumulation process.

Bioaccumulation and risk assessment of heavy metals in soil-crop systems in Liujiang karst area, Southwestern China

Evaluating the bioaccumulation and health risk of heavy metals in soil-crop systems is essential in Liujiang karst regions. In the current study, the single and comprehensive uptake effects of heavy metals (i.e., Cu, Cr, Cd, As, and Zn) between rice and sugarcane and their rhizosphere soils were investigated. The estimated daily ingestion (EDI), target hazard quotient (THQ), and hazard index (HI) were estimated for health risk assessments. The results showed that the mean contents of Cu, Cr, Cd, As, and Zn in rice soils were 25.8, 168, 1.91, 20.0, and 160 mg/kg, respectively, and those in sugarcane soils were 28.8, 186, 0.44, 31.0, and 108 mg/kg. Rice soils were mainly contaminated by Cd, and Cd and Cr were the main pollutants in sugarcane soils. The average concentrations of Cu, Cr, Cd, As, and Zn in rice grains were 1.79, 0.15, 0.16, 0.11, and 12.7 mg/kg, respectively, and in sugarcanes were 0.10, 0.036, 0.022, 0.006, and 0.38 mg/kg. Both crops tended to take up Cd more effectively, and rice grains exhibited higher accumulation capacities of heavy metals in edible part than sugarcanes. Prediction models of Cd and comprehensive accumulation factors were established for rice and sugarcane, and different soil factors affect metal accumulation in crops cultivated in different types. Due to the exposure to As and Cd through rice consumption, non-carcinogenic risks are likely to occur in Liujiang residents.

Predicting heavy metals uptake by spinach (Spinacia oleracea) grown in integrated industrial wastewater irrigated soils of Haridwar, India

This investigation aimed to assess the impacts of integrated industrial wastewater (IIW) irrigation on soil properties in the rural area of Haridwar, India, under cultivation of a leafy vegetable, i.e., spinach (Spinacia oleracea). Based on the field data of two cropping years (2016-2017 and 2017-2018), soil characteristics-based prediction models were developed to evaluate heavy metals (HM) uptake by spinach tissues (roots and leaves) using the multivariate regression method. The results showed a significant increase (P < 0.05) in the growth and productivity of spinach plants in IIW irrigated soils as compared to normal borewell water irrigation. For the prediction models, soil parameters including pH, organic matter (%), and HM (mg/Kg) availability showed a significant effect on the HM absorption process by spinach tissues. Besides this, the models were tested using ANOVA (P < 0.001), Student's t test, model efficiency (> 0.50), and coefficient of determination (R² > 0.81) tools. Furthermore, the prediction models were also verified for their applicability in the 2018-2019 cropping year which gave satisfactory outcomes. The findings of this investigation are important in terms of predicting hazardous HM accumulation in the vegetable crops being grown in wastewater irrigated soils.

Spatiotemporal modeling of soil heavy metals and early warnings from scenarios-based prediction

Prediction of soil heavy metal concentrations based on continuous site specific investigation can provide reference for soil metal contamination prevention and early warning of soil environmental quality. In this study, the spatiotemporal variations of soil heavy metals (Cd, Ni, Zn, Pb and Cu) in Wenling were analyzed with 132 and 169 soil samples gathered in 2011 and 2016. In addition, we adopted a scenario-simulation model to predict future dynamic concentrations of soil heavy metals under optimistic (the pollution inputs are zero under strict environmental policy) and default (the pollution status maintain constant) conditions. Results indicated that the paddy soil was contaminated mainly by Cd and Cu. Spatiotemporal maps revealed distinct patterns in the joint area, where soil Cd, Ni, Zn, Pb and Cu all increased in northwest. Soil heavy metal concentrations as well as the associated ecological risks would decline gradually under optimistic scenario, while sharply increase when no control acts are taken over long term in default condition. The percentages of soil Cd and Cu that exceeding their corresponding risk screening value (RSV) under the default condition would be 1.6 and 1.3 times higher than those under optimistic scenario 10 years later. The probability of high potential ecological risk in default condition would be twice higher than that under optimistic scenario in 2026. Overall, strengthening the control of pollution sources and strict environmental policy are very important for soil heavy metals contamination prevention and control.

Biomonitoring potential of the native aquatic plant Typha domingensis by predicting trace metals accumulation in the Egyptian Lake Burullus

The ability of the native emergent macrophytes Typha domingensis for monitoring pollution with trace metals in Egyptian Lake Burullus was investigated through developing regression models for predicting their concentrations in the plant tissues. Plant samples (above-ground shoot and below-ground root and rhizome) as well as sediment samples were collected monthly during one growing season and analyzed. The association of trace metals concentration with several sediment characteristics (pH, organic matter, clay and silt) was also studied using the simple linear correlation coefficient (r). The concentration of some trace metals was significantly proportional to its values in the sediment such as Cd in the shoot, rhizome and root, Fe in the rhizome, and Ag in the root. There was positive relationship between the bioaccumulation factor (BAF) of Ag, Cd, Fe, Pb and Zn and sediment pH, organic matter and clay content. The developed regression models were significantly valid with high model efficiency and coefficient of determination, and low mean normalized average error. Trace metals were accumulated in the below-ground root and rhizome rather than in the shoot. Only Ag, Co and Ni provided bioaccumulation factor (BAF) < 1, while Ag was the only trace metal that could be transferred to some extend from the root to the rhizome and from there to the shoot [translocation factor (TF) 2.55 and 1.15, respectively]. Typha domingensis in Lake Burullus could be regarded as a bioindicator of trace metals pollution, and a good candidate as phytoremediator for Ag. The information on the phytoremediation capacity of T. domingensis certainly helps to solve contamination problems at Egyptian Lake Burullus region using this native plant.

Uptake Prediction of Ten Heavy Metals by Eruca sativa Mill. Cultivated in Soils Amended with Sewage Sludge

This study was carried out to develop mathematical regression equations for predicting the uptake of ten heavy metals (HMs) (cadmium, Cd; cobalt, Co; chromium, Cr; copper, Cu; iron, Fe; manganese, Mn; molybdenum, Mo; nickel, Ni; lead, Pb; zinc, Zn) by a vegetable species (Eruca sativa Mill.) in the Abha region (Saudi Arabia) based on the concentration of these HMs in soils amended with sewage sludge, organic matter (OM) content and soil pH. The resultant regression equations indicated that the three soil factors were significant predictors for the uptake of the ten HMs in the plant tissues. By applying a t test, we found that there are no significant differences between the actual and predicted values of the ten HMs in the E. sativa roots and leaves (P > 0.05), which reflects the goodness of fit of these equations for predicting the uptake of these HMs. Such types of equations may be helpful for evaluating the risk of cultivation of E. sativa plants in soils amended with sewage sludge.

Prediction models for evaluating heavy metal uptake by Pisum sativum L. in soil amended with sewage sludge

The present study aims to develop prediction models for estimating the potential uptake of 10 heavy metals (HMs) (cadmium, Cd; cobalt, Co; chromium, Cr; copper, Cu; iron, Fe; manganese, Mn; molybdenum, Mo; nickel, Ni; lead, Pb; zinc, Zn) by the tissues of Pisum sativum (root, shoot and pod) grown in soil amended with sewage sludge (SS) under greenhouse conditions. Soil organic matter (OM) was estimated by loss-on-ignition at 550 °C for 2 h. The pH was determined by shaking the soil and pure water at a 1:5 ratio. For HM quantifications, 0.5-1.0 g of each soil or plant sample was digested using a tri-acid mixture digestion method. The quantities of selected HMs were estimated by means of inductively coupled plasma optical emission spectrometry. Bio-concentration (BCF) and translocation (TF) factors were <1 for most of the HMs. In addition, simple linear correlations were significantly negative between the BCF of all studied HMs and soil pH, except for Pb, Mn and Ni, whereas significant positive correlations were observed between BCFs and soil OM, except for Mn, Ni and Zn. The accumulation of the 10 HMs in P. sativum tissues was predicted using regression models based on the values of the same HM in the soil as well as its pH and OM. The calculated prediction models performed well for most HMs in P. sativum tissues (except Ni in the pod, Cd in the shoot and Mn in the root). All measured soil factors (HM, pH and OM) consistently contributed to HM concentrations in the three tissues of the studied plants. These models may help to evaluate the safe cultivation of this species in soil amended with SS.

Old leaves accumulate more heavy metals than other parts of the desert shrub Calotropis procera at a traffic-polluted site as assessed by two analytical techniques

Calotropis procera is a perennial big shrub that has the potential to accumulate high concentrations of heavy metals. Metal sequestration in old organs has been considered as a mechanism for plant survival in polluted soils. The aim of the present study was to assess the role of the old leaves as a sink for HMs accumulation in C. procera. Two instruments were used: atomic absorption spectroscopy (AAS) and X-ray fluorescence (XRF) microscopy. Soil and plant samples were collected from around one of the worst congested traffic areas in the United Arab Emirates (UAE). Samples from roots, stem, and green and old leaves were prepared and analyzed by both instruments. Calotropis procera was able to concentrate Fe, Mn, Sr, and Zn in the roots, but their translocation to stem and green leaves was low. Old leaves had greater ability to accumulate significantly higher concentrations of different metals, especially Fe and Sr, than other parts of the plants, indicating that C. procera uses these metabolically less-active leaves as sinks for heavy metals. Fe and Sr attained higher bioconcentration and accumulation values, compared to Zn and Mn. There were significant positive correlations between XRF and AAS for all elements in the different organs.