Health risk assessment and growth characteristics of wheat and maize crops irrigated with contaminated wastewater

Zinc oxide nano-flowers improve the growth and propagation of mulberry cuttings grown under different irrigation regimes by mitigating drought-related complications and enhancing zinc uptake

Silkworm larvae mainly consume mulberry leaves; therefore, mulberry cultivation is important for the production of raw silk. Drought stress and micronutrient deficiency (Zn) are known to affect the propagation of mulberry cuttings. In this purview, the current investigation attempted to inspect the efficacy of different concentrations of zinc oxide nano-flower (ZnNFs) applied through both soil admixture and foliar spray on the propagation of mulberry cuttings grown under deficit irrigation regimes. The overall results demonstrated that the ZnNF-treated plant cuttings were well-adapted to drought stress and performed better in comparison to the control set. Out of the tested concentrations - ZnNF-10 (applied as 10 mg/kg soil and 10 ppm as foliar spray thrice) was found to be optimum, showing relatively better initial root establishment, the emergence of leaves, and survival and sprouting percentage. Further studies also confirmed an improvement in the accumulation of photosynthetic pigments, carbohydrates, and protein content even under extreme drought conditions. Most importantly, the ZnNF-10 treatment contributed to ROS detoxification and cell membrane protection by enhancing the pool of antioxidant enzymes. The study further demonstrated that ZnNF-10 application enhanced zinc content by 147.50%, 179.49%, and 171.99% in root, shoot, and leaves of the treated cuttings; thereby, improving the bioaccumulation factor of the plant parts. All of these interactive phenomena led to an increment in shoot height, biomass, leaf area, and leaf number of cuttings. These findings, therefore, indicated that ZnNFs can be developed as a promising nano-fertilizer for mulberry growth facilitating Zn uptake and mitigation of drought-induced complications.

Risk assessment of trace metals in Solanum lycopersicum L. (tomato) grown under wastewater irrigation conditions

Heavy metal contamination of food crop plants is viewed as a global issue. Heavy metals like cadmium (Cd), copper (Cu), lead (Pb), chromium (Cr), zinc (Zn), nickel (Ni), arsenic (As), cobalt (Co), and mercury (Hg) are poisonous. Depending on their concentration and capacity for bioaccumulation, they can provide a range of health risks.This research sought to investigate the effects of toxic metals (TMs) on the growth characteristics of produced tomatoes grown under wastewater irrigation. Additionally, it looked into the potential repercussions of both domestic and foreign individuals consuming this plant. In south Cairo, Egypt, two study locations were looked into: a control site in Abu Ragwan, which received water from tributaries of the Nile River, and a contaminated site in El-Shobak El-Sharky, which had raw industrial wastewater. The nutrients of soil and tomato plants (N, P, and K) decreased (P < 0.01), while TMs increased (P < 0.001) significantly as a result of using wastewater for irrigation. Except for Cu, all examined TM accumulating in tomato plants' roots as opposed to shoots had a bioaccumulation factor (BF) > 1. However, the tomato plant's shoot had solely undergone Pb and Ni translocation and storage, with a translocation factor (TF) > 1. A significant amount of Fe (5000.1 mg kg-1), Pb (360.7 mg kg-1), and Mn (356.3 mg kg-1) were present in the edible fruits. The ingestion of contaminated crops increases the daily intake rate of metals (DIR). The values of the high hazard quotient (HQ) were obtained (2073.8 and 2558.9 for Pb, 574.0 and 708.3 for Cd, and 41.1 and 50.7 for Fe for adults and children, respectively). Therefore, tomato plants grown in soils irrigated with untreated wastewater may offer a greater danger to human health, indicating that they should not be grown as a crop for human consumption.

Phytoaccumulation of zinc and its associated impact on the growth performance and tolerance index of six non-food crop plants grown in Zn-contaminated soil

Crop plant remediation and detoxification of Zn-contaminated soils may pose a significant threat to food safety and, thus, human health. Therefore, the current study was carried out to assess the ability of six non-food crop plants (NFCP); Zea mays L. cultivar 360 (T360), Z. mays cultivar 123 (T123), Helianthus annuus L., Brassica juncea (L.) Czern., Ricinus communis L., and Simmondsia chinensis (Link) C.K. Schneid to remediate and restore Zn-contaminated soils. The investigated plants tolerate 150 mg/kg of Zn content of the soil, where they had tolerance index (TI) > 1 for all growth criteria, except the root dry weight (DW) of S. chinensis. Z. mays T123 and R. communis were the most susceptible plants, while B. juncea and S. chinensis were moderately tolerant, while H. annuus was the most tolerant to high Zn concentrations in a growing medium. Increasing the soil Zn content led to a significant increase (p < 0.05) in Zn concentration in the various tissues of the six NFCPs. The studied NFCP did not translocate Zn to their grains/seeds; consequently, they can be used safely for Zn-contaminated soils. The Zn content in root and shoot was negatively correlated with the TI of their length and weight, while the translocation factor (TF) of Zn from root to shoot was positively correlated to the TI of the root length and weight. The six studied NFCPs were arranged based on their phytoremediation efficiency as follows: B. juncea (31.86%) > Z. mays T123 (31.14%) > Z. mays T360 (27.59%) > H. annuus (20.85%) > S. chinensis (20.29%) > R. communis (15.3%). All tested NFCPs accumulated significant concentrations of Zn in their roots and shoots, a high Zn uptake potential, and biomass at 150-450 mg/kg of Zn treatments, indicating that these plants are good candidates for the implementation of a new strategy of cultivating NFCP for phytoremediation of Zn-contaminated soils.

Meta-analysis of public health risks of lead accumulation in wastewater, irrigated soil, and crops nexus

Lead (Pb) from different sources accumulate in the irrigation water, irrigated soil and in different parts of plants. Reports show contradictory findings and high variability of lead accumulation and associated public health risks. We hypothesized that lead accumulation in irrigation water, soil and edible plants is high enough to be a public health risk. By using the standard procedures for meta-analysis, 24 studies were qualified. The studies included in the meta-analysis are concentrated in few countries with strong authors' key words co-occurrence relationship. The mean concentration of Pb in the irrigation wastewater ranged from 0.0196 ± 0.01 mg/l to 52.4 ± 0.02 mg/l in wastewater and about 50% of the values are beyond the limits for irrigation water standard. The study also showed that the concentration of Pb in the irrigated soil vary significantly from a minimum of 0.04 ± 2.3 mg/l in Ethiopia to a maximum of 441 ± 19.8 mg/l in Iran (P < 0.01). Based on effect size analysis, the weight of the studies ranged from 0.1 to 5.4% indicating that the studies' contribution to the overall effect is barely different. The heterogeneity test statistics also indicates considerable variability between the studies (I² = 98%, P-value < 0.001). The subgroup analysis showed large between-studies heterogeneity in both groups (Tau² = 28.64; T² = 98%). A total of 44 crops were studied, of which 38 were leafy and non-leafy vegetables. Most popular crops including spinach, cabbage and lettuce are most frequently studied crops. In all crops, the Pb level in crops produced by using untreated wastewater are beyond the WHO limit for edibility. In all of the studies, the pollution load index (PLI) and soil accumulation factor (SAF) is much higher indicating that there is a buildup of Pb concentration in wastewater irrigated soil. The plant concentration factor (PCF) calculated shows the high Pb accumulation potential of the edible parts of the crops. The health risk index (HRI) calculated shows that in all of the studied crops from India, Iraq, Morocco and Egypt are much higher than one indicating the high health risk of consumption.

Comparative zinc tolerance and phytoremediation potential of four biofuel plant species

Soil pollution has become a serious environmental problem worldwide due to rapid industrialization and urbanization. Zinc (Zn) contamination has raised concerns about potential effects on plants and human health. This study was conducted to assess the capability of four biofuel plants: Abelmoschus esculentus, Avena sativa, Guizotia abyssinica, and Glycine max to remediate and restore Zn contaminated soil. Selected plants were grown in soil exposed to different Zn treatments (50, 100, 200, 300, 400, 600, 800 and 1000 mg Zn kg^-1) for 12 weeks. Soil without spike taken as control. Zn induced toxicity significantly (p < 0.05) reduced seed germination and inhibited plant growth and leaf chlorophyll content. The investigated plants can tolerate a soil content of 800 mg Zn kg^-1 with the exception of A. sativa, which was most tolerant to high Zn concentrations (1000 mg Zn kg^-1) for all growth criteria. Moreover, increasing Zn content in soil resulted in a significant (p < 0.05) increase in Zn accumulation in various tissues of the four biofuel plants. According to phytoremediation efficiency, the four biofuel plants studied were arranged as follows: A. sativa (5.05%) > A. esculentus (4.15%) > G. max (2.31%) > G. abyssinica (1.17%). This study concluded that all tested biofuel plants species, especially A. sativa exhibited high Zn concentrations in roots and shoots, high Zn uptake capability, high tolerance, and high biomass at 50-800 mg Zn kg^-1 treatments. Consequently, these biofuel plants are excellent candidates for phytoremediation in Zn contaminated soils.

Co-exposure of potentially toxic elements in wheat grains reveals a probabilistic health risk in Southwestern Guizhou, China

Bijie is located at a typical karst landform of Southwestern Guizhou, which presented high geological background values of potentially toxic elements (PTEs). Recently, whether PTE of wheat in Bijie is harmful to human health has aroused people's concern. To this end, the objectives of this study are to determine the concentrations of PTE [chromium (Cr), nickel (Ni), arsenic (As), lead (Pb), cadmium (Cd), and fluorine (F)] in wheat grains, identify contaminant sources, and evaluate the probabilistic risks to human beings. A total of 149 wheat grain samples collected from Bijie in Guizhou were determined using the inductively coupled plasma mass spectrometer (ICP-MS) and fluoride-ion electrode methods. The mean concentrations of Cr, Ni, As, Cd, Pb, and F were 3.250, 0.684, 0.055, 0.149, 0.039, and 4.539 mg/kg, respectively. All investigated PTEs met the standard limits established by the Food and Agriculture Organization except for Cr. For the source identification, Cr and Pb should be originated from industry activities, while Ni, As, and Cd might come from mixed sources, and F was possibly put down to the high geological background value. The non-carcinogenic and carcinogenic health risks were evaluated by the probabilistic approach (Monte Carlo simulation). The mean hazard quotient (HQ) values in the three populations were lower than the safety limit (1.0) with the exception of As (children: 1.03E+00). However, the mean hazard index (HI) values were all higher than 1.0 and followed the order: children (2.57E+00) > adult females (1.29E+00) > adult males (1.12E+00). In addition, the mean carcinogenic risk (CR) values for Cr, As, Pb, and Cd in three populations were all higher than 1E-06, which cannot be negligible. The mean threshold CR (TCR) values were decreased in the order of children (1.32E-02) > adult females (6.61E-03) > adult males (5.81E-03), respectively, all at unacceptable risk levels. Moreover, sensitivity analysis identified concentration factor (C _W ) as the most crucial parameter that affects human health. These findings highlight that co-exposure of PTE in wheat grains revealed a probabilistic human health risk. Corresponding measures should be undertaken for controlling pollution sources and reducing the risks for the local populace.

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.

Heavy-Metal Speciation Distribution and Adsorption Characteristics of Cr (VI) in the Soil within Sewage Irrigation Areas

While sewage irrigation relieves water shortages in Northern China, its excessive application triggers a series of environmental problems, such as heavy-metal pollution. Soil profile and river sediment profile samples from the sewage irrigation area (SIA) were collected by selecting the farmlands in which sewage irrigation activity has been reported since the 1960s, around Huiji River (HJR) and Huafei River (HFR) in Kaifeng, Henan Province, China, as research areas. In this study, the total amount of heavy metals (Cr, Cd, Pb, Mn, Zn, and Ni) and the heavy-metal speciation analysis using the modified BCR sequential extraction method were used to evaluate the impacts of wastewater on agricultural soils and the potential risk. Furthermore, the least contaminated Cr (VI) was selected for the study of adsorption characteristics to determine the environmental capacity of soils for heavy metals when the composition of wastewater changes under long-term effluent irrigation conditions. The results show that: (1) the concentrations of heavy metals in soil continuously decreased with depth, while the opposite was observed in sediment, reflecting the continuous improvement in water quality over the historical period; (2) In the topsoil, the mean concentrations (mg·kg−1) in rank order are as follows: Mn (588.68) > Zn (284.21) > Pb (99.76) > Cr (76.84) > Ni (34.71) > Cd (3.25), where Cd exceeded the control value by 3.15 times around HFR, and sediment samples also showed higher heavy metal concentrations in HFR than in HJR; (3) Speciation distribution and risk assessment code (RAC) indicate that Mn and Cd were at medium risk and that Cd warrants attention due to its being a non-essential toxic element in humans; (4) The adsorption rates of soil in various layers in different profiles within SIAs for Cr (VI) gradually increased with the increasing initial content of Cr (VI). Among the three isothermal adsorption models, the fit result obtained by the Langmuir equation was superior to those obtained by the Freundlich equation and the linear equation.

Accumulation and translocation of eight trace metals by the different tissues of Abelmoschus esculentus Moench. irrigated with untreated wastewater

Due to water scarcity, the use of wastewater to irrigate crops is on the rise all over the world, including in Egypt (particularly untreated wastewater). The purpose of this study is to see if irrigation with untreated industrial wastewater in natural fields can cause Abelmoschus esculentus Moench. (okra plant) to accumulate and translocate eight trace metals (lead: Pb, cadmium: Cd, chromium: Cr, copper: Cu, iron: Fe, manganese: Mn, nickel: Ni, and zinc: Zn) in its different tissues. It was extended to look at the effects of wastewater irrigation on the farmed okra plants' growth characteristics, nutrients, colors, and organic content. Two studied sites at South of Cairo have been investigated: the first site (29°42'31.17" N and 31°15'11.56" E) represented by five cultivated fields irrigated with Nile water (control) and the second site (29°42'37.87" N and 31°17'14.53" E) fields irrigated with effluent received untreated industrial wastewater. Three composite soil and irrigated water samples were collected from each site. Because of wastewater irrigation, soil and plant nutrients (nitrogen, potassium, and phosphorus) decreased significantly (at P < 0.01), whereas trace metals increased significantly (at P < 0.01 and P < 0.05) for soil and plant samples irrigated with untreated wastewater. Due to irrigation with untreated wastewater, there was also a significant decrease in okra growth metrics (at P < 0.05) and leaves photosynthetic pigments: chlorophyll a and b, and carotenoids (at P < 0.01 and P < 0.05). In the plant's fruits (edible section) watered with wastewater, iron was the most abundant metal. Besides, Cd, Cu, Fe, Mn, Ni, and Zn concentrations were also in the phytotoxic range (42.57, 140.67, 2756.67, 1293.33, 1326.67, and 877.83 mg kg^-1, respectively). All trace elements examined accumulate in the roots of wastewater irrigated okra (Bioaccumulation factor > 1). Okra plants, on the other hand, did not have an accumulated trace metals strategy in their shoots since the translocation factor was less than one. Because of substantial trace metal accumulation in their edible sections, the scientists advised against eating okra plants grown in fields watered with untreated wastewater.

Effect of Marginal-Quality Irrigation on Accumulation of some Heavy Metals (Mn, Pb, and Zn) in TypicTorripsamment Soils and Food Crops

Lack of active sorption sites in sandy soils renders metals added by irrigation water more labile and increases their soil-to-plant transfer. Thus, this study investigated the long-term impacts of irrigation using sewage effluents and contaminated groundwater on metal accumulations in TypicTorripsamment soils, and edible parts of food crops. Nine sites in El-Gabal El-Asfar farm, south-eastern to the Nile Delta of Egypt, were selected. At each site, irrigation water, soil (0–30 cm), and the crop’s edible part were sampled in triplicates and analyzed for Mn, Pb, and Zn. Results revealed significant (p < 0.05) differences in metal concentrations among water sources. Thus, constant irrigation caused significant spatial variations in total and available metal contents in soils. Total contents of Pb (in four sites) and Zn (in all sites) exceed the lithosphere range, while the available contents of the three metals exceeded the safe limits in all soils. The index of geo-accumulation indicated no Mn pollution but showed elevated pollution risks for Pb and Zn. The three metals showed high availability ratios, proving the effect of light soil texture. The multivariate statistical analysis indicated that Mn and Zn had similar geochemical behaviors in soils. Metal contents in all crop’s edible parts surpassed the safe limits. The bioaccumulation factor (BAF) was less than 1.0 for Mn and Zn but higher than 1.0 for Pb. The highest BAFs occurred in cabbage leaves, indicating the phytoextraction potential of this species. Sufficient water treatment and proper remediation techniques are recommended to alleviate metal accumulation in food crops and their transfer via the food chain.

Bioaccumulation and human health risk assessment of heavy metals in food crops irrigated with freshwater and treated wastewater: a case study in Southern Cairo, Egypt

Food safety has often attracted attention worldwide. Few studies have investigated the heavy metal (HM) pollution and health risk assessment of crops and vegetables. The current work was conducted to evaluate the human risk assessment of HM (Cu, Cd, Cr, Pb, and Zn) in radish, lettuce, tomato, onion, turnip, squash, okra, sunflower, Jews mallow, and garden rocket cultivated in treated wastewater (TWW)-irrigated sites as compared with those cultivated in freshwater (FW)-irrigated sites. Irrigation water, soil, and different plants were collected from 6 farmlands irrigated with TWW and two agricultural sites irrigated with FW (Nile river). Heavy metal transfer factor (HMTF), chronic daily intake of metals (CDIM), health hazard risk (HR), and health hazard index (HI) were estimated. The results showed that the tested HM levels in FW and TWW were below the Food and Agriculture Organization (FAO) and Egyptian standards recommended for irrigation. In soil samples, HM levels were below the permissible limits for both tested sites. The HM in soil and plants grew in TWW-irrigated sites possessed multiple levels higher than those grown in FW-irrigated sites. Among different plants, HM levels in the edible parts of plants grown in TWW-irrigated sites followed in decreasing order: tomato > sunflower >Jew's mallow = turnip = squash > lettuce > okra = radish > onion > garden rocket. The mean CDIM and HR values of plants irrigated using TWW were higher than those irrigated using FW. Furthermore, HR values for all plants grown in polluted and unpolluted sites were < 1 except Cd in plants grown in the TWW-irrigated farmlands. The mean HI for radish, lettuce, tomato, onion, turnip, squash, okra, sunflower, Jews mallow, and garden rocket grown in TWW-irrigated sites were 2.08, 2.39, 1.76, 1.53, 2.08, 1.80, 2.03, 1.91, 1.82, and 1.44 (for adult), and 2.39, 2.75, 2.71, 1.75, 2.38, 2.06, 2.33, 2.69, 2.10, and 1.65 (for children). Plants irrigated with TWW showed a higher HMTF than plants irrigated with FW. Jew's mallow and okra irrigated with TWW had a maximum HMTF. Consequently, different practical measures can be taken to minimize the HM levels in agricultural foodstuffs. These measures include preventing the excessive application of pesticides and fertilizers for crop production and continuous monitoring of different foodstuffs in the market.

Bioaccumulation and translocation of trace elements in soil-irrigation water-wheat in arid agricultural areas of Xin Jiang, China

Pollution resulting from toxic trace elements is an increasing concern around the world especially in developing countries such as China. Rapid industrialisation, urbanisation and agricultural development are the dominant sources of anthropogenic contamination contributed to an increased potential toxicity of trace elements in the irrigation water-soil-food chain. Xin Jiang in China is a reserved cultivated land development area that could provide the most extensive strategic support for food production and arable land security in China. Thus, it is crucial to investigate the bioaccumulation and translocation of trace elements in order to assess the ecological and human health risks in the traditional oasis system of the agricultural areas in Bay Cheng County, Xin Jiang. This study analysed the levels of trace elements in different layers of the soil, the irrigation water and the wheat plants, and the relationships among them. The results indicated that cadmium (Cd) and chromium (Cr) were the primary pollutants in soils and wheats respectively, and they fell into the serious pollution category. However, no trace elements over the pollution limits were detected in irrigation water. The maximum values of trace elements appeared in the soil layers at 5-10 cm and 10-15 cm. The pollution levels of trace elements in the soil layers were found at 0-5 cm and 0-20 cm, which were higher than those at 20-80 cm. In wheat, high amounts of absorption for Se, Cr, Zn and Cu, but low for Pb were detected in different parts of a plant. The roots of wheats were more eco-toxic to Cd, Co and Pb than other tissues, indicating that roots were more effective at absorbing Cd, Co and Pb, as these metals are usually toxic in the soil. Se, Cu and Zn showed a higher ability of being transferred from soils to the edible parts of crops. The bio-transfer factors of Zn, Mo, Cu, Mg and Mn were considerably higher than those of other elements. The average cancer risk of As, Cd, Co, Ni and TCR in wheat grains exceeded the safety reference limit (1 × 10^-4). For the exposed population, Cr in wheat was the major contributor to total cancer risk. The average values of HQ of Cr, Mn and As, and total non-cancer risk index exceeded the corresponding effective safe reference doses (HQ > 1).

Toxic element profile of ice cream in Bangladesh: a health risk assessment study

Ice cream is a popular frozen dairy product and a possible source of dietary minerals. However, ice cream may also contain toxic metals, which may cause several health implications. The current study aimed to determine the content of toxic elements in ice cream samples using inductively coupled plasma-optical emission spectrometry (ICP-OES) and to assess the health risks of consumers based on target cancer risk (TCR), target hazard quotient (THQ), and hazardous index (HI). The determined concentration (median, range) of all studied elements had shown a descending order of Al (9.36, 5.37-14.26) > Zn (5.94, 1.95-10.22) > Cu (1.73, 1.02-3.77) > Ni (0.95, 0.67-1.80) > Fe (0.79, 0.10-1.64) > Cr (0.43, 0.28-0.73) > Mn (0.42, 0.11-1.03) > Pb (0.34, 0.09-0.79) > Cd (0.08, 0.04-0.14) mg/kg (fresh weight). The values of THQ and HI (except 16% for children) were lower than the maximum threshold risk limit (TRL = 1.0), indicating no potential non-carcinogenic health effects might occur. Similarly, the TCR of Cr and Pb for both adults and children was within the permissible limit of 10^-4-10^-6, which suggested that the consumer would not experience potential lifetime carcinogenic health risks. However, the overall analyses revealed that the consumption of ice cream is almost safe for people, but the combined impact of all metals (HI) in some samples is a matter of health concern. Henceforth, regular monitoring of toxic metals in ice creams should be done to assure food safety and hygiene.

Geogenic enrichment of potentially toxic metals in agricultural soils derived from black shale in northwest Zhejiang, China: Pathways to and risks from associated crops

Agricultural soils derived from black shale are typically enriched in potentially toxic metals. This is a serious problem, both in terms of the ecological environment and human health. To assess the levels of potentially toxic metals, 90 paired soil-crops samples were collected from the Anji Country, western Zhejiang province, a typical exposed black shale area in China. Concentrations and bioavailability of potentially toxic metals in the soil-crops system were measured, and the associated potential risks were further evaluated. Results showed the enrichment of potentially toxic metals (i.e. Cd, Pb, Cu, Zn and Ni) in the soil and crop samples, especially a significant accumulation of Cd. Sequential extraction data indicated that Cd in soils derived from black shale was the second most dominant element in the exchangeable fraction (mean at 33.42%) and possessed high bioavailability, whereas Pb was mostly retained in the residual fraction (mean at 76.34%) and exhibited low mobility. The total concentration as well as mobility and bioavailability of Cd were the highest in the sampled soils. This resulted in a high potential ecological risk in areas with agricultural soils derived from black shale, which could eventually jeopardize the health of local residents through various exposure pathways. Overall, our findings provide a scientific basis for developing suitable management strategies to mitigate the exposure to potentially toxic metals in high risk areas.

Occurrence of heavy metal in water, soil, and plants in fields irrigated with industrial wastewater in Sabata town, Ethiopia

Industrial wastes have been increasingly discharged into water and soil, and causing environmental pollution in Ethiopia. This study examined the occurrence of heavy metal in water, soil, and plants in fields irrigated with industrial wastewater in Sabata town, Ethiopia. The composite samples of soil, water, and vegetables were collected accordingly to determine the concentration of heavy metals (Cu, Pb, Zn, Mn, and Ni) in each system during dry and wet seasons. The concentration of heavy metal was assayed using atomic absorption spectrophotometry. The data were statistically analyzed using one-way ANOVA. The heavy metal concentration was decreased in the order of Pb > Mn > Ni > Cu > Zn, Mn > Ni > Pb > Cu > Zn, and Ni > Pb > Mn > Cu > Zn in the water, soil, and vegetables in the area respectively. The variation of levels of heavy metal in the water, soil, and vegetable might be because of the effect of heavy metal speciation and valence, industry types, vegetable types and tissues, and soil. The bioconcentration factor of heavy metals was higher than that one for copper, signifying the increased probability of health risk for those who are consuming vegetables grown in the area. Thus, the government should take this into account and devise mitigation strategies through the implementation of heavy metal removal systems from contaminated water and soil, waste management strategies of recycling, centralized or decentralized treatment plant, changing of industrial residual into biogas production, and awareness creation for the society.

Input-output balance of cadmium in typical agriculture soils with historical sewage irrigation in China

The gradual increase of cadmium (Cd) in soils has caused environmental and health risk, and it's important to study the accumulation trend to evoke the awareness of farmland safety management. This research during the period of March in 2017-2018 evaluated the input (irrigation, atmospheric deposition, fertilizer and pesticide application) and the output (runoff and seepage, grain and straw uptake) of Cd in contaminated farmland irrigated with sewage water in Hebei Province. The experimental results indicated sewage irrigation (51.03%), and atmospheric deposition (46.35%) were the main input pathways; Grain uptake (42.72%) and straw removal (50.71%) played a major role in output fluxes. The input-output balance (net transport fluxes) of Cd in the farmland were estimated to be +3621.68 ~ +8899.78 mg·(ha·yr)^-1 under different conditions (sewage irrigation with straw returning/straw removal, clean water irrigation with straw returning/straw removal), representing there was a Cd inputting in the farmland during the study. Even in the case of the lowest net transport fluxes, the annual increase of Cd concentration in soils reached to 0.0014 mg/kg. Therefore, it's necessary to take action that cutting off those pathway inputs into farmland ecosystems, such as monitoring the water quality of irrigation water sources, applying fertilizer and pesticide properly. Furthermore, attentions need to be paid to the Cd input into the farmland and environmental risks that may arise while returning straw to the field for improving soil fertility and crop production.

Potentially toxic element (PTE) levels in maize, soil, and irrigation water and health risks through maize consumption in northern Ningxia, China

BACKGROUND

Industrial and agricultural activities result in elevated levels of potentially toxic elements (PTEs) in the local environment. PTEs can enter the human body through the food chain and pose severe health risks to inhabitants. In this study, PTE levels in maize, soil, and irrigation water were detected, and health risks through maize consumption were evaluated.

METHODS

Maize, soil, and irrigation water samples were collected in northern Ningxia, China. Inductively coupled plasma-optical emission spectrometry was applied to determine the contents of six PTEs. Bioaccumulation factor was used to reflect the transfer potential of a metal from soil to maize. Health risks associated with maize consumption were assessed by deterministic and probabilistic estimation. Sensitivity analysis was performed to determine variables that pose the greatest effect on health risk results.

RESULTS

The levels of Pb and Cr in maize exceeded the standards, while the PTE levels in soil and irrigation water did not exceed the corresponding standards. The bioaccumulation factor values of the six PTEs in maize were all lower than 1 and followed the order of Cd > Zn = As > Cr > Cu > Pb. The hazard index (0.0986) was far less than 1 for all inhabitants implying no obvious non-carcinogenic risk. The carcinogenic risk value was 3.261 × 10^- 5, which was lower than the maximum acceptable level of 1 × 10^- 4 suggested by United States Environmental Protection Agency (USEPA). Females were at greater risk than males, and the age group of below 20 years had the greater risk among all the groups evaluated. Approximately 0.62% of inhabitants exceeded the level for non-carcinogenic risk, while 8.23% exceeded the level for carcinogenic risk. The As concentration and daily intake of maize contributed 35.8, and 29.4% for non-carcinogenic risk results as well as 61.0 and 18.5% for carcinogenic risk results.

CONCLUSIONS

Maize was contaminated by Pb and Cr, whereas the associated soil and irrigation water were not contaminated by PTEs. Inhabitants would not suffer obvious harmful health risks through maize consumption. Arsenic level and daily intake of maize were the most sensitive factors that impact health risks.

Early responses of maize seedlings to Cu stress include sharp decreases in gibberellins and jasmonates in the root apex

Copper (Cu) interferes with numerous biological functions in plants, including plant growth, which is partly governed by plant hormones. In the present study, Cu stress effect on the roots of pre-emerging maize seedlings in terms of growth, nutrient composition, protein modifications, and root hormone homeostasis was investigated, focusing on possible metabolic differences between the root apex and the rest of the root tissues. Significant decreases in root length and root biomass after 72 h of Cu exposure (50 and 100 μM CuCl₂), accompanied by reductions in Ca, Mg, and P root contents, were found. Cu also generated cell redox imbalance in both root tissues and revealed by altered enzymatic and non-enzymatic antioxidant defenses. Oxidative stress was evidenced by an increased protein carbonylation level in both tissues. Copper also induced protein ubiquitylation and SUMOylation and affected 20S proteasome peptidase activities in both tissues. Drastic reductions in ABA, IAA, JA (both free and conjugated), GA3, and GA4 levels in the root apex were detected under Cu stress. Our results show that Cu exposure generated oxidative damage and altered root hormonal homeostasis, mainly at the root apex, leading to a strong root growth inhibition. Severe protein post-translational modifications upon Cu exposure occurred in both tissues, suggesting that even when hormonal adjustments to cope with Cu stress occurred mainly at the root apex, the entire root is compromised in the protein turnover that seems to be necessary to trigger and/or to sustain defense mechanisms against Cu toxicity.

Effect of biochars on bioaccumulation and human health risks of potentially toxic elements in wheat (Triticum aestivum L.) cultivated on industrially contaminated soil

In the present study, biochars (BCs) derived from naturally grown green waste (Cynodon dactylon L.) were investigated regarding their impacts on bioaccumulation of potentially toxic elements (PTEs), agronomic properties and human health risks of wheat crop cultivated on long-term industrially contaminated soil. Typically, three types of BCs were pyrolyzed at different highest temperature of treatment (HTT), i.e. 400 °C, 600 °C and 800 °C, in a horizontal reactor and applied to the contaminated soil with 2% and 5% (w/w) ratio. The characterization results of the BCs showed that significant positive changes in fundamental characteristics such as porosity, surface area, cation exchange capacity, dissolved organic carbon, phosphorus and potassium have occurred with increased HTT. The analytical results of wheat crop indicated that the BCs applications significantly (p ≤ 0.05) reduced concentration of PTEs in roots (48-95%), shoots (38-91%), leaves (30-91%) and grains (38-93%) of wheat plants. After the BCs application, the agronomic properties were enhanced up to 6-18%, 18-38%, 17-46%, 13-45%, 15-42%, 22-55% and 34-57% for germination rate, shoot length, shoot biomass, spike length, spike biomass, grain biomass and root biomass respectively. The human health risks of PTEs were significantly (p ≤ 0.05) decreased (31-93%) from toxicity level to safe level (except for Mn and Cu), after the BCs application. Based on the current study, the BCs (especially 800BC5) were recommended for reducing bioaccumulation of PTEs in different parts of the wheat plant, increasing growth and yield of wheat crop and decreasing human health risks via consumption of wheat grains.

Spatial-temporal characteristics and driving factors of the human health impacts of five industrial aquatic toxic metals in China

With the rapid advancement of industrialization without effective supervision, industrial aquatic toxic metal (TM) emissions pose threats to human health in China. Due to differences in socioeconomic development, the regional disparity of industrial aquatic TM emissions is obvious nationwide. In this study, the human health impacts (HHIs) of industrial aquatic TM emissions (i.e., mercury (Hg), cadmium (Cd), hexavalent chromium (Cr(VI)), lead (Pb), and arsenic (As)) in the 31 provinces of China were evaluated based on the ReCiPe method, and the driving factors affecting HHIs from 2000 to 2015 were decomposed using the logarithmic mean Divisia index (LMDI) method. The results showed that the HHIs gradually decreased, with more than an 80% decrease from 2000 to 2015. The order of the TMs contributing to the national HHIs in 2015 was as follows: As (79.5%) > Cr(VI) (19.6%) > Hg (0.4%) > Pb (0.2%) = Cd (0.2%), and 21 (68%) provinces were dominated by industrial aquatic As emissions. Economic development is the major driving factor of the increase in HHIs, while the HHI strength and wastewater discharge intensity are the key driving factors causing reductions in the HHIs. Hunan, Inner Mongolia, Hubei, and Jiangxi accounted for approximately 55% of the total HHIs in 2015. Some suggestions for reducing HHIs based on the local realities of different provinces were put proposed considering two aspects: economic strategy and technical capability.

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.

Hazards assessment of the intake of trace metals by common mallow (Malva parviflora K.) growing in polluted soils

Human risks increase by consuming plants growing in trace/heavy metals contaminated soil irrigated with polluted water. The present study aims to assess the ability of common mallow to accumulate trace/heavy metals from polluted soils at South Greater Cairo, Egypt; and their hazardous effects on consumer's health. Five quadrats were used to collect soil and plant samples from three sites of un-polluted and polluted fields for chemical analysis and measurement of growth variables, as well as for assessing the daily intake of metals (DIM) and hazard quotient (HQ). Irrigation water analysis showed elevated concentrations of the investigated metals and mineral salts in the polluted area compared with the un-polluted one. Plant samples showed reduction in their growth parameters; as well as pigments and nutrient content in the metal-contaminated soil. In addition, Pb, Cd, Cu, Ni, Fe, Mn, Zn, and Co concentrations in the shoots and roots of plants grown in polluted fields were higher compared with plants grown in un-polluted site. The bioaccumulation and translocation factors of most investigated metals indicated the great ability of common mallow to accumulate such metals, which would increase the human intake of metals in their daily diets compared to their reference values (R_fD). The hazard quotient (HQ) of Pb, Cr, Fe, Mn and Zn for children and Pb, Cd, Fe and Mn for adults was >1, indicating health hazards for the consumers of common mallow cultivated in the polluted area.

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.

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

The present study was conducted using a pot experiment to develop regression models for the prediction of trace metal concentrations in faba bean (Faba sativa Bernh.) plants cultivated in soils amended with different rates of sewage sludge to monitor possible human health risks. The trace metal concentrations in the different tissues of faba bean showed that most of the investigated trace metals were accumulated in the plant roots rather than in the other tissues. Meanwhile, the fruits accumulated the lowest concentration of most trace metals. The trace metal concentrations of the faba bean plants had a significant positive correlation with the organic matter content and a significant negative correlation with the soil pH. Transfer of trace metals from the soil to faba bean roots indicated that Al, Cu, Pb and Zn had a transfer factor that exceeded one, whereas the TF of the investigated trace metals from the roots to the fruits did not exceed one. The daily intake rate of the investigated trace metals did not exceed one in both adults and children. On the other side, the hazard quotient of trace metals from consuming faba bean fruits had values <1 for most investigated trace metals except Al and Mn in adults and in children. It is worth mentioning that the predicted trace metal concentrations via the established regression models and measured values from the validation data set were not significantly different (P > 0.05). Therefore, these developed models will be useful for prediction of trace metals uptake by faba bean grown in soil amended with sewage sludge so possible human risks can be identified.

A framework for selecting crops for irrigation using mining contaminated water: An example from the Olifants basin of South Africa

Irrigated agriculture is adapting to viability challenges due to water contamination from mining in various ways. We explore the option of using crops that are able to tolerate the impacts of such water contamination as a short term adaptation strategy. We present a framework which enables the selection of crops suitable for irrigated production using mining contaminated water. The framework identifies key factors that should inform crop selection; and these include crop adaptation to climatic conditions, contaminants present in water, crop tolerance to contaminants, crop use and accumulation of toxic metals. A proposed process for screening and selecting a crop is described. Although considered a partial analysis due to incomplete and non-standardised information on crop tolerance levels, the framework narrows down choices which can be assessed in more detail or with field trials. The framework shows that interventions beyond the farm level are necessary to support the use of contaminant tolerant crops as a strategy for adapting to water contamination from mining. However, key questions regarding the risks associated with alternative crops and difficulties in selecting suitable crops remain.

Prediction models for evaluating the heavy metal uptake by spinach (Spinacia oleracea L.) from soil amended with sewage sludge

The risk evaluation of polluted soil requires the application of precise models to predict the heavy metal uptake by plants so possible human risks can be identified. Therefore, the present work was conducted to develop regression models for predicting the concentrations of heavy metals in spinach plants from their concentration in the soil by using the organic matter content and soil pH as co-factors. The soil improved with sewage sludge was slightly alkaline and had a relatively high organic matter content. Similar to the soil analysis, Fe had the highest median concentration, while Cd had the lowest concentration in the roots and leaves. Heavy metals accumulated in the roots and leaves in the order Fe > Mn > Zn > Cu > Cr > Ni > Co > Pb > Cd. The bio-concentration factor of the investigated heavy metals, from soil to roots, did not exceed one. The spinach was recognized by a translocation factor <1.0 for all of the heavy metals except Zn. Plant heavy metal concentrations were positively correlated with the soil organic matter content and negatively correlated with soil pH. The leaf Cr, Fe and Zn and the root Cr, Fe, Pb and Zn concentrations were positively correlated with the respective soil heavy metals. In addition, a linear correlation was found between the bio-concentration factor of heavy metals and soil pH and organic matter content. Regression models with high model efficiency and coefficients of determination and low mean normalized average errors, which indicate the efficiency of the models, were produced for predicting the plant heavy metal contents by using the soil pH and organic matter content as co-factors.

Human health risks from consuming cabbage (Brassica oleracea L. var. capitata) grown on wastewater irrigated soil

The present study investigated the impact of cumulative irrigation with wastewater on the soil properties and, its health hazards on the consumers of cabbage plants at south Cairo Province, Egypt. Irrigation water, soil and cabbage plants were sample d from two polluted and other two unpolluted farms. The physicochemical properties of water and soil were analyzed and the growth parameters, as well as nutrients and heavy metals concentration in cabbage were investigated. In addition, the daily intake of metals (DIM) and health risk index (HRI) were estimated. Wastewater posed a decrease in the availability of N, P and K, but increases heavy metals in the soil solution. Cabbage stem and root lengths as well as the number of leaves and biomass were greatly reduced in the polluted farms. In addition, the photosynthetic pigments, carbohydrates and proteins were decreased under pollution stress. The concentration of most investigated metals in the leaves and roots were increased with translocation factor greater than one for Pb, Cd, As, Cr, Ni, Fe, and Co. The study revealed that the HRI exceeded one for Pb and Cd in polluted and unpolluted plants; and Fe in polluted ones. Irrigation with wastewater is not suitable for cabbage as it has health risks on humans due to accumulation of heavy metals. It worth noting that, the high ability of cabbage plants to accumulate Pb and Cd from both polluted and unpolluted soils should be taken into consideration when consuming this plant.

Prediction models for evaluating the uptake of heavy metals by cucumbers (Cucumis sativus L.) grown in agricultural soils amended with sewage sludge

Heavy metal (HM) concentrations in edible plants can develop many serious health risks to humans. The precise prediction of plant uptake of HMs is highly important. Thus, the present investigation was carried out to develop regression models for predicting the concentrations of HMs in cucumbers (Cucumis sativus L.) from their concentration in the soil and using the organic matter (OM) content and soil pH as co-factors. The results showed that cucumber roots had the highest significant concentrations of all HMs at P < 0.001, except Cd, Cu, and Zn were in fruits. The lowest concentrations of Cd, Co, Cr, Mn, Ni, and Pb were recorded in stems. HM concentrations in cucumbers were strongly correlated with soil HM, pH, and OM content. Soil pH and OM content had negative and positive correlations with all HMs in cucumber tissues, respectively. Regression analysis indicated that soil HM, pH, and OM contents were good predictors for HM concentrations in cucumbers. The regression models for root Co, Cr, Fe, and Zn were described by high model efficiency values that explain 48-58% variability. The best regression models for cucumber stem were for Cu, Mn, Ni, and Zn that are characterized by high R² and model efficiency values. For cucumber fruits, R² values were ranged from 54 to 82%, with best models for Cr, Pb, Cd, Cu, Ni, and Co in the fruit. We expect that these models will be beneficial for risk assessment studies on sewage sludge utilization in agriculture.

Heavy metal accumulation by Corchorus olitorius L. irrigated with wastewater

Many agricultural soils in Egypt irrigated with untreated wastewater. Herein, we investigated the effect of untreated industrial wastewater irrigation on the soil and fodder plant Corchorus olittorius (Jew mallow). It also aimed to assess its effect on the growth measurements as well as analyses of soils, irrigation waters, and plants for heavy metal and nutrient concentrations. Significant differences between irrigation waters and soil irrigated with fresh and wastewater were recognized. Wastewater irrigation leads to remarkable reduction in the growth parameters and reduced its vegetative biomass. The concentration of Pb, Cd, Cr, Cu, Fe, and Zn were high significant and above phytotoxic concentrations in leaves (edible part) and roots of wastewater-irrigated plant. The present study indicated that Jew mallow plant tends to phytostabilize (Cd, Ni, and Mn) in its root and had the ability to translocate (Pb, Cu, Cr, Fe, and Zn) to its leaves. Higher concentrations of Cd, Cu, Cr, Pb, Fe, Mn, Ni, and Zn in the roots than leaves indicate that the roots are hyper-accumulators for Pb, Cr, Cu, Fe, and Zn more than the leaves. The research study recommended that there is a need to protect the soil from contamination through regular monitoring and not to cultivate Jew mallow in wastewater-irrigated soil and that it had a high capacity to accumulate heavy metals in its edible part and causes several harmful health effects for consumers.

A Review of Environmental Contamination and Health Risk Assessment of Wastewater Use for Crop Irrigation with a Focus on Low and High-Income Countries

Population densities and freshwater resources are not evenly distributed worldwide. This has forced farmers to use wastewater for the irrigation of food crops. This practice presents both positive and negative effects with respect to agricultural use, as well as in the context of environmental contamination and toxicology. Although wastewater is an important source of essential nutrients for plants, many environmental, sanitary, and health risks are also associated with the use of wastewater for crop irrigation due to the presence of toxic contaminants and microbes. This review highlights the harmful and beneficial impacts of wastewater irrigation on the physical, biological, and chemical properties of soil (pH, cations and anions, organic matter, microbial activity). We delineate the potentially toxic element (PTEs) build up in the soil and, as such, their transfer into plants and humans. The possible human health risks associated with the use of untreated wastewater for crop irrigation are also predicted and discussed. We compare the current condition of wastewater reuse in agriculture and the associated environmental and health issues between developing and developed countries. In addition, some integrated sustainable solutions and future perspectives are also proposed, keeping in view the regional and global context, as well as the grounded reality of wastewater use for crop production, sanitary and planning issues, remedial techniques, awareness among civil society, and the role of the government and the relevant stakeholders.