An approach for evaluating the bioavailability and risk assessment of potentially toxic elements using edible and inedible plants—the Remance (Panama) mining area as a model

Mining affects the environment, particularly through the persistence of accumulation of tailings materials; this is aggravated under tropical climatic conditions, which favours the release of potentially toxic elements (PTEs) bioavailable to the local flora and fauna and supposing a risk to human health. The Remance gold mine (Panamá), exploited intermittently for more than 100 years, and has remained derelict for over 20 years. Within the area live farmers who carry out subsistence agriculture and livestock activities. The objective of this study has been to study the transference of PTEs in the local agricultural soil-plants system, with the goal of identifying their bioavailability to perform a human risk assessment. The results obtained of the Bioaccumulation coefficient in local plants show very weak to strong absorption of As (< 0.001–1.50), Hg (< 0.001–2.38), Sb (0.01–7.83), Cu (0.02–2.89), and Zn (0.06–5.32). In the case of Cu in grass (18.3 mg kg−1) and plants (16.9 mg kg−1) the concentrations exceed the maximum authorised value in animal nutrition for ruminants (10 mg kg−1). The risk to human health for edible plants exceeds the non-carcinogenic risk for rice, corn, cassava, and tea leaves for Sb (HQ 19.450, 18.304, 6.075, 1.830, respectively), the carcinogenic risk for Cu (CR = 2.3 × 10–3, 7.7 × 10 −4, 1.1 × 10–3, 1.0 × 10–3, respectively), and the carcinogenic risk for As in rice, corn and tea leaves (CR = 8 × 10–5, 3 × 10–5, 3 × 10–5, respectively). Urgent measures are needed to alleviate these effects.

Accumulation and translocation of toxic elements from contaminated soils to plants, Nigeria: Implications for metal potential hazards to humans.

Soil pollution by heavy metals, their health effect on humans via the food chain are pressing issues of the environment caused by human activities. Plant’s accumulation and translocation potentials were investigated to determine their suitability for phytoremedial purposes, and the potential of the edibles/vegetables to cause harm to humans when consumed. Plant and soil samples were collected, prepared, digested in acid mixture of H2O2 and HNO3 for plants and Li2B4O7 − LiBO2 for soils and were analysed. These analyses were carried out to determine the concentration of these metals in soil, their accumulation and translocation in plant parts. The data acquired were evaluated using bioconcentration (BCF), translocation factor (TF), bioaccumulation coefficient (BAC), metal uptake efficiency (ME%) and hierarchical cluster analysis to determine hyperaccumulators, phytoextractors, phytostabilizers, metal source plants and metals that could be toxic to humans through intake of roots, grains/seeds, fruits and leaves as vegetables. ANOVA analysis revealed that the data were significant at p < 0.05. Correlation and cluster analyses were employed to understand the relationships between variables determined. From this study, Colocasia asculenta (CA), Corchorus aestuans (COA) and Laportea aestuans (LA) were hyperaccumulators of Co at various points. Arsenic has phytostabilizer plants from the study. COA and LA were phytostabilizers of Cd while Sida acuta was the only phytoextractor. The concentration of metals in the vegetables/edibles in roots, shoots and leaves were above permissible levels for Cr, Co and Cd. The metal uptake efficacy (%) were in this order Co (28.99 to 89.08) > Cd (21.74 to 50.96) > Cr (22.90 to 49.06) > and As (9.65 to 39.19).

Accumulation and Translocation of Toxic Elements From Contaminated Soils, Nigeria: Implications for Phytomining and Hazards to Humans

Soil pollution by heavy metals and their health effect on human are pressing issues of the environment caused by human activities. Plant’s accumulation and translocation potentials were investigated to determine their suitability for phytoremedial purposes, their ability to serve as reservoir for recovery of additional economic amount of metals and the potential of the edibles/vegetables to cause harm to humans when consumed. The plant and soil samples were collected, prepared, digested in acid mixture of H2O2 and HNO3 for plants and Li2B4O7 - LiBO2 for soils and were analysed. The analyses were carried out to determine the concentration of these metals in soil, their accumulation and translocation in plant parts. The data acquired were evaluated using bioconcentration (BCF), translocation factor (TF), bioaccumulation coefficient (BAC), metal uptake efficiency (ME%) and hierarchical cluster analysis to determine hyperaccumulators, phytoextractors, phytostabilizers, metal source plants and metals that could be toxic to humans through intake of roots, grains/seeds, fruits and leaves as vegetables. ANOVA analysis revealed that the data were significant at p <0.05. Correlation and cluster analyses were employed to understand the relationships between variables determined. From this study, CA, COA and LA were hyperaccumulators of Co at various points. Arsenic has only phytostabilizers. COA and LA were phytostabilizers of Cd while Sida acuta was the only phytoextractor. Chromium, Co and Cd have prospect of being phytomined from some of the plants. Vegetables/edibles values in shoots and leaves were above permissible levels for Cr, Co and Cd. The metal uptake efficacy (%) were in this order Co (28.99 to 89.08) > Cd (21.74 to 50.96) >Cr (22.90 to 49.06) > and As (9.65 to 39.19).

Human Health Risk Assessment and Potentially Harmful Element Contents in the Cereals Cultivated on Agricultural Soils

Potentially harmful element (PHE) contents were investigated in six species of cereals in southern Poland, with human health risk implications assessed afterwards. The PHE contents belonged to the following ranges (mg/kg wet weight): As below the limit of detection (<LOD)–0.013, Cd <LOD–0.291, Co <LOD–0.012, Cu 0.002–11.0, Hg <LOD–0.080, Ni <LOD–8.40, Pb <LOD–12.0, Sb <LOD–0.430, Tl <LOD–0.160, and Zn 5.47–67.7. The Pb and Cd contents exceeded the maximum allowable concentration (MAC) values for wheat, oat, rye, and barley in the Śląskie region. The bioaccumulation coefficient (BA) for the total PHE content in the soil indicated that cereals had no potential of PHE accumulation. Regarding the statistical daily consumption of cereals, the PHE intake rates, expressed as a percentage of permissible maximum total daily intake (% PMTDI), were the following: As 0.0003, Cd 0.193, Co 0.0003, Cu 0.075, Hg 0.424, Ni 3.94, Pb 3.16, Sb 0.23, Tl 0.27, and Zn 0.44. The total non-carcinogenic risk values (HQ) exceeded the target risk value of 1 for wheat (HQ = 13.3) and rye (HQ = 3.44). For other cereals, the total non-carcinogenic risk values decreased in the following order: barley (HQ = 0.47) > oat (HQ = 0.38) > maize (HQ = 0.02). The total non-carcinogenic risk value of the statistical daily consumption of cereals was acceptable low (HQ = 0.58). The acceptable cancer risk (CR) level of 1.0 × 10−5 investigated only for As was not exceeded under any of the intake scenarios. Concerning the mean As content in cereals consumed daily in statistical amounts the CR value was equal to 5.1 × 10−8. The health risk value according to the Pb content in cereals using the margin of exposure (MOE) approach was equal to 1.27, indicating an acceptable low risk.

Development of the limit values of micronutrient deficiency in soil determined using Mehlich 3 extractant for Polish soil conditions. Part II. Rapeseed

The aim of the study was to develop limit values for low microelement concentration in the soil, determined with the use of Mehlich 3 extractant for assessing their deficits in rapeseed crops. The values were prepared on the basis of 1944 fields with rapeseed, covering the whole Poland. In 2017, the samplers of Polish agro-chemical laboratories took soil samples and corresponding plant samples at the BBCH 30/31 stage. In the plant samples, the concentration of microelements was determined, and in the soil samples, apart from microelements, also pH, texture and the concentration of organic carbon and available phosphorus, were determined. Moreover, for each field, data on rapeseed yield were collected. Limit values were determined by two independent methods: 1) the method of regression equations and 2) the so-called high yield method. In the first case, the limit microelement concentration in the soil was calculated from the equation describing the relationship between the R/G bioaccumulation coefficient and a specific soil feature (n=1944). The bioaccumulation coefficient is a quotient of the concentration of a microelement in a plant (R) and its concentration in the soil determined by the Mehlich 3 (G) method. Limit values were calculated after substituting the critical concentration of microelements in the plant (R) to the equation, and subsequently, an appropriate conversion of the equation. The second method was based on the separation of a group of high yields ≥4.0 t ha−1 (n=755) from the whole data set. Then in this group, the lower quintiles (QU1) were calculated for the concentration of individual microelements in the soil determined in Mehlich 3 extract and adopted as limit values. It was found that QU1 is a good indicator of the lowest microelement concentration in the soil at which a yield of at least 4.0 t ha−1 can be obtained. The final limit values were worked out by averaging the values calculated by the equations and high yield method and their appropriate correction. In the combined soil sample collections for wheat and rapeseed (n=3865), the values were checked by evaluating the percentage of soils with microelement shortage separately for rape and wheat. The results of this evaluation were compared with the evaluation using the old system based on the 1 M HCl, which did not take into account the plant species.

Effect of polluted water on soil and plant contamination by heavy metals in El-Mahla El-Kobra, Egypt

The discharge of untreated waste water in Zefta drain and drain no. 5 is becoming a problem for many farmers in the El-Mahla El-Kobra area, Egypt. The discharged water contains high levels of contaminants considered hazardous to the ecosystem. Some plants, soil, water, and sediment samples were collected from the El-Mahla El-Kobra area to evaluate the contamination by heavy metals. The results showed that the heavy metals, pH, sodium adsorption ratio (SAR), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) in the water of Zefta drain and drain no. 5 exceeded permissible limits for irrigation. In rice and maize shoots grown in soils irrigated by contaminated water from Zefta drain and drain no. 5, the bioaccumulation factors for Cd, Pb, Zn, Cu, and Mn were higher than 1.0. The heavy metals content of irrigated soils from Zefta drain and drain no. 5 exceeded the upper limit of background heavy metals. In this study, the mean contaminant factor values of the drain no. 5 sediments revealed that Zn, Mn, Cu, Cd, Pb, and Ni > 6, indicating very high contamination. The bioaccumulation coefficient values of Cynodon dactylon, Phragmites australis, and Typha domingensis aquatic plants growing in Zefta drain are high. These species can be considered as hyperaccumulators for the decontamination of contaminated water.

An assessment of urban habitat contamination with selected heavy metals within the city of Katowice using the common dandelion (Taraxacum officinale Web.) as a bioindicator

The common dandelion (Taraxacum officinale Web.) is considered to be a good indicator species due to its wide spread and high tolerance to harsh environmental conditions. It was used in this study to assess contamination with selected heavy metals (Zn, Pb, Cd) within urban habitats of the city of Katowice (southern Poland). Samples were collected from outside the forest regions. Content of heavy metals was determined using Flame Atomic Absorption Spectroscopy (F-AAS). The soil mineralization was conducted using 50,0 cm3 10% HNO3. Determination of elemental concentrations in the plant material was carried out with the “wet” method using heating blocks for a period of 7-10 days. The following concentration ranges for individual elements in soil were found: 14,03–2049,50 mg kg−1 (Pb), 17,91–4118,00 mg kg−1 (Zn), 0,25–52,93 mg kg−1 (Cd). Concentrations within the leaves of common dandelion were: 5,52–93,04 μg g−1 (Pb), 71,71–807,15 μg g−1 (Zn), 0,10–15,69 μg g−1 (Cd). Plants from the most heavily contaminated soils were characterised by the lowest bioaccumulation coefficient. The most contaminated areas were the districts: Szopienice-Burowiec and Wełnowiec-Józefowiec, while the least contaminated were the southern districts of Katowice (i.e. Zarzecze, Podlesie). There is also a clear link between the content of heavy metals in soils examined in this study and the land use.

Copper Accumulation and Tolerance of Chlorophytum comosum

In this study, Copper (Cu) tolerance inChlorophytum comosumwas tested by pot-planting. The results showed that the tolerance index (TI) ofC. comosumwas above 100 in soil Cu concentration of 50mg·kg-1. With the increase of Cu concentration in soil, the MDA content increased, but had no significant differences with the control until 500mg·kg-1. The value of chlorophyll a/b had no significant differences with the control in all treatments. Meanwhile, the bioaccumulation coefficient (BC) and translocation factor (TF) value ofC. comosumwere 1.287 and 0.687 respectively in Cu concentration of soil up to 500mg·kg-1. For the advantages of high tolerance, high accumulation and high ornamental value,C. comosummay be a potential Cu-accumulator and have tremendous application value in the treatment of Cu-contaminated soils.

Distribution of heavy metals in freshwater ecosystem of a small stream impacted by urban drainage

This paper focuses on the study of heavy metals' remobilisation possibilities and changes of distribution coefficients leading to remobilisation in a stream as a result of changing conditions caused by urban drainage. The paper also reports consequent changes of bioaccumulation coefficient for different species of the benthic community, which seems to be the best indicator of aquatic community quality in small urban streams. The paper presents results obtained during field monitoring as well as results obtained during laboratory experiment. The field monitoring identified in the study area (the Botič Creek) three heavy metals (Cu, Zn and Pb), which are the main sources of toxicological risk in this area. Based on the monitoring, these elements were used for laboratory experiment, where their behaviour during changing conditions was studied. The experiment shows that changing conditions in the stream, caused by urban drainage, significantly impact the fate of heavy metals in aquatic ecosystems and that these elements have different preferences to bind to a particular geochemical fraction of sediment, which consequently means different bioavailability.