Kinetics of glyphosate and aminomethylphosphonic acid sorption onto montmorillonite clays in soil and their translocation to genetically modified corn.

The co-occurrence of glyphosate (GLP) and aminomethylphosphonic acid (AMPA) in contaminated water, soil, sediment and plants is a cause for concern due to potential threats to the ecosystem and human health. A major route of exposure is through contact with contaminated soil and consumption of crops containing GLP and AMPA residues. However, clay-based sorption strategies for mixtures of GLP and AMPA in soil, plants and garden produce have been very limited. In this study, in vitro soil and in vivo genetically modified corn models were used to establish the proof of concept that the inclusion of clay sorbents in contaminated soils will reduce the bioavailability of GLP and AMPA in soils and their adverse effects on plant growth. Effects of chemical concentration (1-10 mg/kg), sorbent dose (0.5%-3% in soil and 0.5%-1% in plants) and duration (up to 28 days) on sorption kinetics were studied. The time course results showed a continuous GLP degradation to AMPA. The inclusion of calcium montmorillonite (CM) and acid processed montmorillonite (APM) clays at all doses significantly and consistently reduced the bioavailability of both chemicals from soils to plant roots and leaves in a dose- and time-dependent manner without detectable dissociation. Plants treated with 0.5% and 1% APM inclusion showed the highest growth rate (p ≤ 0.05) and lowest chemical bioavailability with up to 76% reduction in roots and 57% reduction in leaves. Results indicated that montmorillonite clays could be added as soil supplements to reduce hazardous mixtures of GLP and AMPA in soils and plants.

Evaluating the mouse model for estimation of arsenic bioavailability: Comparison of estimates of absolute bioavailability of inorganic arsenic in mouse, humans, and other species.

Accurate assessment of adverse health effects attributable to ingestion of inorganic arsenic (As) present in contaminated soils requires determination of the internal dose of metal provided by ingested soil. This calculation requires estimation of the oral bioavailability of soil-borne (As). Animal models to assess the bioavailability of soil (As) are frequently used as surrogates for determination of this variable in humans. A mouse assay has been widely applied to estimate the bioavailability of As in soils at sites impacted by mining, smelting, and pesticides. In the mouse assay, the relative bioavailability (RBA) of soil (As) is determined as the ratio of the fraction of the ingested arsenic dose excreted in urine after consumption of diets containing a test soil or the soluble reference compound, sodium arsenate. The aim of the current study was to compare (As) bioavailability measured in the mouse assay with reported estimates in humans. Here, a pharmacokinetic model based on excretion of arsenic in urine and feces was used to estimate the absolute bioavailability (ABA) of As in mice that received an oral dose of sodium arsenate. Based upon this analysis, in mice that consumed diet amended with sodium arsenate, the ABA was 85%. This estimate of arsenic ABA for the mouse is comparable to estimates in humans who consumed (As) in drinking water and diet, and to estimates of ABA in monkeys and swine exposed to sodium arsenate. The concordance of estimates for ABA in mice and humans provides further support for use of the mouse model in human health risk assessment. Sodium arsenate ABA also provides a basis for estimating soil arsenic ABA from RBA estimates obtained in the mouse model.

Bioavailability and health risk of toxic heavy metals (As, Hg, Pb and Cd) in urban soils: A Monte Carlo simulation approach.

Toxic heavy metals pollution in urban soil has become a major global issue due to its adverse effects on the environment and human health. In this paper, 26 soil samples were analyzed to assess the speciation, bioavailability and human health risk of Arsenic (As), Mercury (Hg), Lead (Pb) and Cadmium (Cd) in urban soils of a heavy industrial city in NE China by using a Monte Carlo simulation approach. The results showed that As, Hg, Pb and Cd concentrations in the soil all exceed the corresponding background value of study area. Mercury displays the highest value of geo-accumulation index (Igeo), followed by Cd, Pb and As. The pollution load index (PLI) value (>2) indicates a moderate pollution level in the study area. The chemical speciation of HMs mainly exists in residual fraction except Cd. The probabilistic health risk assessment demonstrated that the mean values of Total Carcinogenic Risk (TCR) and Hazard Index (HI) calculated with total concentration are at the unacceptable level, with a higher risk to children than adults. However, the mean values calculated with bioavailable fraction are all within the acceptable level. The mean value of TCR and HI obtained by bioavailable fraction is about 96% and 95% lower than that obtained by total concentration, respectively. Thus, this study suggested that the bioavailable fraction of HMs is a more reliable parameter for health risk assessment, while the total concentration of HMs can overestimate the true risk. The results of this study provide some insight into the speciation, bioavailability and health risks of toxic heavy metals in urban soils in those heavy industrial cities.

Characterization and quantification of chlordecone elimination in ewes.

To reduce the exposure of the French West Indies population to the organochlorine insecticide chlordecone (Kepone; CLD), the contamination of currently consumed foodstuffs must be reduced. Depuration of contaminated animals before slaughter could be a strategy to obtain safe animal products. The aim of this study was to characterize and quantify CLD elimination in contaminated ewes during depuration process. Experiments A and B consisted in a single intravenous (i.v.) administration of CLD (n = 5) and CLDOH (chlordecol; n = 3) followed by a 84-d and 3-d depuration period respectively with collection of blood, faeces and urine samples. After CLD administration, CLD and conjugated-CLDOH (CLDOH-C) were quantified in serum and urine and CLD and CLDOH were quantified in faeces. Based on calculations of faecal, urinary and body clearances of CLD and CLDOH-C, faeces appeared as the major route of CLD excretion with 86 % of the CLD administered dose eliminated in faeces, either as CLD (51 %) or as CLDOH (35 %).

Quantification of field-incurred residues of cyantraniliprole and IN-J9Z38 in cabbage/soil using QuEChERS/HPLC-PDA and dietary risk assessment.

Cyantraniliprole is an anthranilic diamide insecticide used for the effective management of diamondback moth in cabbage. Dietary risk assessment of pesticides in food is a major concern now. This study developed a QuEChERS/HPLC-PDA-based highly efficient and reliable method, registering 89.80-100.11% recoveries of cyantraniliprole and its metabolite IN-J9Z38 from cabbage and soil with a relative standard deviation of 0.43-5.77%. Field experiment was conducted to study the residue dissipation of cyantraniliprole in cabbage and soil. Two foliar treatments of 10.26% formulation (Benevia) at 60 (T1 ) and 120 (T2 ) gram active ingredient/hectare were applied. The dissipation half-lives of cyantraniliprole in cabbage and soil were determined to be 3.5-4.2 and 3.8-5.3 days at T1 and 3.9-4.8 and 4.1-4.7 days at T2 , respectively. The maximum concentrations of IN-J9Z38 at T1 and T2 were 0.819 and 1.061 mg/kg, respectively, on the fifth day. A risk quotient value of <1 indicates no dietary risk to the consumers. The residues in the harvested cabbage were below the tolerance level of 2.0 mg/kg established by the regulatory body in India.

An interlaboratory evaluation of the variability in arsenic and lead relative bioavailability when assessed using a mouse bioassay.

Animal bioassays have been developed to estimate oral relative bioavailability (RBA) of metals in soil, dust, or food for accurate health risk assessment. However, the comparability in RBA estimates from different labs remains largely unclear. Using 12 soil and soil-like standard reference materials (SRMs), this study investigated variability in lead (Pb) and arsenic (As) RBA estimates employing a mouse bioassay in 3 labs at Nanjing University, University of Jinan, and Shandong Normal University. Two performances of the bioassay at Nanjing University in 2019 and 2020 showed reproducible Pb and As RBA estimates, but increasing the number of mouse replicates in 2020 produced more precise RBA measurements. Although there were inter-lab variations in diet consumption rate and metal accumulation in mouse liver and kidneys following SRM ingestion due to differences in diet composition, bioassays at 3 labs in 2019 yielded overall similar Pb and As RBA estimates for the 12 SRMs with strong linear correlations between each 2 of the 3 labs for Pb (R2 = 0.95-0.98 and slope = 0.85-1.02) and As RBA outcomes (R2 = 0.46-0.86 and slope = 0.56-0.79). The consistency in RBA estimates was attributed to the relative nature of the final bioavailability outcome, which might overcome the inter-lab variation in diet consumption and metal uptake in mice. These results increased the confidence of use of mouse bioassays in bioavailability studies.

Constructing slow-release formulations of herbicide metribuzin using its co-extrusion with biodegradable polyester poly-ε-caprolactone.

Different technologies to prepare long term pesticide forms include polymer coating, preparing composites and encapsulating pesticides in nanoparticles. A simple and low-cost method was proposed to obtain slow-release formulations by co-extrusion of a pesticide with a biodegradable polymer at a temperature above the melting points of both components. A herbicide metribuzin and low-melting polyester poly-ε-caprolactone were chosen for this work. Formulations containing 10%, 20%, and 40% herbicide were prepared. During 7 days of their exposition in water, it was released from 81% to 96% of initially loaded metribuzin; the highest release was detected for 40%-loaded forms. Biodegradation of the constructs and pesticide release were further studied in the model soil. Degradation rates of the specimens increased with an increase in pesticide content, from 9% to 20% over 14 weeks for the 10%/20%-loaded and the 40%-loaded specimens, respectively. The release of metribuzin reached, respectively, 37-38% and 55%. The herbicide content in soil was lower due to its partial degradation in soil; it reached 23-25% and 33%, respectively, from initially loaded into the polymer matrix. Release kinetics of metribuzin in water as in soil best fitted the First-order model. The used approach is promising for obtaining long-term release formulations for soil applications.

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil.

Plant growth-promoting rhizobacteria (PGPR) mediate heavy metal tolerance and improve phytoextraction potential in plants. The present research was conducted to find the potential of bacterial strains in improving the growth and phytoextraction abilities of Brassica nigra (L.) K. Koch. in chromium contaminated soil. In this study, a total of 15 bacterial strains were isolated from heavy metal polluted soil and were screened for their heavy metal tolerance and plant growth promotion potential. The most efficient strain was identified by 16S rRNA gene sequencing and was identified as Bacillus cereus. The isolate also showed the potential to solubilize phosphate and synthesize siderophore, phytohormones (indole acetic acid, cytokinin, and abscisic acid), and osmolyte (proline and sugar) in chromium (Cr+3) supplemented medium. The results of the present study showed that chromium stress has negative effects on seed germination and plant growth in B. nigra while inoculation of B. cereus improved plant growth and reduced chromium toxicity. The increase in seed germination percentage, shoot length, and root length was 28.07%, 35.86%, 19.11% while the fresh and dry biomass of the plant increased by 48.00% and 62.16%, respectively, as compared to the uninoculated/control plants. The photosynthetic pigments were also improved by bacterial inoculation as compared to untreated stress-exposed plants, i.e., increase in chlorophyll a, chlorophyll b, chlorophyll a + b, and carotenoid was d 25.94%, 10.65%, 20.35%, and 44.30%, respectively. Bacterial inoculation also resulted in osmotic adjustment (proline 8.76% and sugar 28.71%) and maintained the membrane stability (51.39%) which was also indicated by reduced malondialdehyde content (59.53% decrease). The antioxidant enzyme activities were also improved to 35.90% (superoxide dismutase), 59.61% (peroxide), and 33.33% (catalase) in inoculated stress-exposed plants as compared to the control plants. B. cereus inoculation also improved the uptake, bioaccumulation, and translocation of Cr in the plant. Data showed that B. cereus also increased Cr content in the root (2.71-fold) and shoot (4.01-fold), its bioaccumulation (2.71-fold in root and 4.03-fold in the shoot) and translocation (40%) was also high in B. nigra. The data revealed that B. cereus is a multifarious PGPR that efficiently tolerates heavy metal ions (Cr+3) and it can be used to enhance the growth and phytoextraction potential of B. nigra in heavy metal contaminated soil.

Phytoremediation of potentially toxic elements using constructed wetlands in coastal areas with a mining influence.

This paper proposes the use of wetlands as a phytoremediation strategy for areas of mining and maritime influence in the southeast of Spain. Potentially toxic elements (PTEs) tolerant and salinity-resistant macrophytes (Phragmites australis, Juncus effusus and Iris pseudacorus) have been used. The experiment is carried out in an aerobic artificial wetland using representative sediments affected by mining activities in the study area. Selected species were placed in pots containing substrates made with different mixtures of topsoil and/or peat, mining residues (black or yellow sand). After six months, rhizosphere, root and aerial parts were collected. A transfer study of As, Pb, Zn and Cu is performed, determining contents in rhizosphere and plant (aerial and underground part). From these data, the TF and BCF were calculated for each plant in 15 different substrates. The work is complemented by an initial study of scanning electron microscopy (SEM-EDX) of plants. The obtained results indicate a tolerance of the metallophytes to these PTEs, which may favour the obtaining of a naturalized habitat that acts as an effective protective barrier to the ecosystem, that is easy to maintain and that avoid the risk of transfer to the trophic chain. The use of these species can be a complement to the chemical stabilization proposed for the whole area and carried out in experimental plots. Because they are perennial plants, it is necessary to continue with the experiments and obtain results in a longer period of time that allows to evaluate yield and stabilization.

Distribution and bioconcentration of some elements in the edible mushroom Leccinum scabrum from locations in Poland.

The element concentrations in the fruitbodies of Leccinum scabrum from two forested upland sites and one lowland site of different geochemical background were compared to topsoil concentrations. The aim of the study was to establish baseline concentration datasets, gain insight into the species' bioconcentration potential and to assess the impact of anthropogenic factors. The validated methods for analysis include inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and cold-vapor atomic absorption spectroscopy (CV-AAS). Bioinclusion (bioconcentration factor > 1) by L. scabrum was observed for the elements Ag, Cd, Cu, K, Hg, Mn, Na, Mg, P, Rb, and Zn. In contrast, the elements Al, Ba, Ca, Fe, Ni, and Sr as well as the toxic Pb were bioexcluded. Among these elements, the toxic elements Cd and Pb are noteworthy regarding the aspect of human mushroom consumption. The medians of Cd in caps of L. scabrum from the upland sites were in the range of 5.6-6.6 mg kg-1 dm, with a maximum in an individual sample of 14 mg kg-1 dm, which is in the range of concentrations reported previously for polluted soils. Lead concentrations were much lower, with medians in the range of 0.79-1.3 mg kg-1 dm in caps and 0.48-0.59 mg kg-1 dm in stipes. Mineral contents of L. scabrum appear to be the result of a complex interaction of a species' characteristic physiology with local mineral soil geochemistry and with anthropogenic pollution factors.

Prospective usage of magnesium potassium phosphate cement combined with Bougainvillea alba derived biochar to reduce Pb bioavailability in soil and its uptake by Spinacia oleracea L.

Combining biochar (BR) with other immobilizing amendments has additive effects on Pb immobilization and been recognized to be effective for the restoration of Pb polluted soils. However, the impacts of different proportions between BR and a highly efficient Pb immobilizing agent called "magnesium potassium phosphate cement (MC)" have never been earlier investigated. This work aimed to investigate the consequences of BR and MC alone and their mixtures of 25:75, 50:50, and 75:25 ratios on Pb bioavailability, Pb immobilization index (Pb-IMMi), and enzymatic activities in Pb polluted soil. Furthermore, amendments effects on Pb distribution in spinach, growth, antioxidant capacity, biochemical, and nutritional spectrum were also investigated. We found that MC alone performed well to immobilize Pb in soil and reducing its distribution in shoots, but was less efficient to improve soil enzymatic activities and plant attributes. Conversely, the application of BR alone stimulated soil enzymatic activities, plant growth, and quality but was less effective to immobilize Pb in soil and reducing shoot Pb concentrations. The combinations of BR and MC of various ratios showed variable results. Interestingly, the most promising outcomes were obtained with BR50%+MC50% treatment which resulted in enhanced Pb-IMMi (73%), activities of soil enzymes, plant growth and quality, and antioxidant capacity, compared to control. Likewise, significant reductions in Pb concentrations in shoots (85%), roots (78%), extractable Pb (73%) were also obtained with BR50%+MC50% treatment, compared to control. Such outcomes point towards a cost-effective approach for reducing Pb uptake by the plants via using MC and BR at a 50:50 ratio.

Effect of soil organic matter on the plant uptake of perfluorooctanoic acid (PFOA) and perfluorooctanesulphonic acid (PFOS) in lettuce on granular activated carbon-applied soil.

The presence of perfluorooctanoic acid (PFOA) and perfluorooctanesulphonic acid (PFOS) in crops is an important consideration for food safety. The soil organic matter (SOM) content may affect the adsorption potential of PFOA and PFOS in water and soil and their subsequent uptake in crops. To better understand these dynamics, the adsorption and uptake of PFOA and PFOS in lettuce were investigated using granular activated carbon (GAC)-treated soils with varying SOM content. The adsorption potential of GAC was investigated, with maximum adsorption capacities for PFOA and PFOS calculated to be 9.091 mg g-1 and 27.778 mg g-1, respectively. These values decreased to 5.208 mg g-1 and 17.241 mg g-1, respectively, after the addition of 0.04 wt% humic acid. The average plant uptake factor (PUF) in low and high perfluoroalkyl and polyfluoroalkyl acid (PFAA)-contaminated soils with 4.0 wt% SOM was restricted to 0.353 for PFOA and 0.108 for PFOS. The PUFs were approximately two times lower than those for soil with 2.6 wt% SOM. Addition of 1 wt% GAC to the soil successfully reduced the PUF by up to 99.4%, with values of 0.006 (PFOA) and 0.005 (PFOS) in 2.6 wt% SOM-treated soil and 0.079 (PFOA) and 0.023 (PFOS) in 4.0 wt% SOM-treated soil. Although the PUF in the GAC-treated soil was drastically decreased, the PUF of the soil with 4.0 wt% SOM was at least four times higher than that with 2.6 wt% SOM. Therefore, SOM content is an important consideration in the remediation of PFOA- and PFOS-contaminated farmland soil using carbonaceous adsorbent.

Effects of a soil organic amendment on metal allocation of trees for the phytomanagement of mining-impacted soils.

The suitable application of phytomanagement by phytostabilisation using plant tree species in metal-polluted soils requires an assessment of the fate of metals in biological tree compartments. The goal of this work was to evaluate the effect of an urban compost amendment on metal allocation in two evergreen tree species (Pinus halepensis and Tetraclinis articulata) growing in a metal-enriched polluted substrate. A comprehensive characterisation of edaphic parameters and metal speciation was carried out. Plant analyses included metal concentrations in different tree compartments: roots, stems, branches and leaves. The amendment caused a significant increase in plant biomass for both trees, although T. articulata produced 2.5 times more biomass than P. halepensis. The amendment alleviated P deficiency in P. halepensis. This did not occur for the N deficiency detected in T. articulata. The latter showed no effect of the amendment in the allocation of metals, being most of them restricted at the root compartment (> 50%). For P. halepensis, similar behaviour occurred for Cu, Pb and Zn. However, for Cd, the amendment caused its redistribution into pine shoots, probably due to its transport associated with the increased transpiration. Results indicated that T. articulata may be a promising tree species to be used in phytomanagement programs under semiarid climates due to its low metal translocation into shoots and remarkable biomass production under amendment conditions.

Contrasted tolerance of Agrostis capillaris metallicolous and non-metallicolous ecotypes in the context of a mining technosol amended by biochar, compost and iron sulfate.

Metal(loid) contamination of soil, resulting from the mining activities, is a major issue worldwide, due to its negative effects on the environment and health. Therefore, these contaminated soils need to be remediated. One realistic method is the assisted phytostabilization, which aims at establishing a vegetation cover on the soil that will reduce metal(loid) bioavailability and spreading through the prevention of wind erosion and water leaching. In addition, amendments are applied to improve soil conditions and ameliorate plant growth. In this goal, biochar and compost showed good results in terms of amelioration of soil fertility and reduction in lead bioavailability. However, they usually have a negative effect on arsenic. On the contrary, iron sulfate showed capacity to reduce arsenic mobility through interaction with its iron hydroxides. Finally, the choice of the appropriate plant species is crucial for the success of assisted phytostabilization. One good option is to use endemic species, adapted to the metal(loid) stress, with a fast growth and large shoot and root systems. The aims of this study were to (1) evaluate the effects of applying biochar, compost and iron sulfate, alone or combined, to a former mine soil on the soil properties and Agrostis capillaris growth, and (2) assess the difference between two Agrostis capillaris ecotypes, an endemic metallicolous ecotype and a non-metallicolous ecotype. Results of the mesocosm experiment showed that amendment application improved soil properties, i.e., reduced soil acidity, increased nutrient availability and lower metal(loid) stress, the best being the combination biochar-compost-iron sulfate. These ameliorations allowed a better plant growth. Finally, the metallicolous ecotype performed better in terms of growth than the non-metallicolous one and could thus be used in an assisted phytostabilization process on the former mine site.

Effect of quarry activities on selected biological resources around quarry site within Onigambari forest plantation, Oyo State, Nigeria.

Quarry activities are creating diverse stress on biological resources in the rural areas where most of them are located globally. In this study, the effect of quarry activities on elephant grass (Pennisetum purpureum) leaves and soils around Onigambari Forest Reserve, Oyo State, Nigeria, were investigated. Soil and samples of elephant grass (Pennisetum purpureum) leaves were collected from two different distances from the quarry plant. Samples used as control were collected within the boundary of Cocoa Research Institute of Nigeria (CRIN), Oyo State, Nigeria estate. Samples were analysed using proton-induced X-ray emission, to determine the elements. The physiochemical parameters were also analysed in both soil and leaves samples. The mean concentration of the elements in the soil sample from Site 1 was higher in Mg, Cl, Ca, Ti, Cr, Mn, Fe, Zn and Zr than Site 2 and the control site. While in leaves, similar trend was observed. Cd and Ag were highly enriched.

Remediation by means of EDTA of an agricultural calcareous soil polluted with Pb.

The dispersion of mine tailings affects ecosystems due to their high content of potentially toxic elements. Environmental risk increases when the soil impacted by tailings is used for agriculture; this use may result in health impacts. This study analyzes the feasibility of remediating a calcareous soil (used for maize cultivation) polluted with lead in the semiarid zone of Zimapán, México, by using EDTA as an extractant. Total geoavailable and bioaccessible concentrations in the gastric and intestinal phases were determined to evaluate lead availability and health risk. The soil was then washed with EDTA, and the geochemical fractionation (interchangeable, carbonates, Fe/Mn oxy-hydroxides, organic matter-sulfides, and residual) and impact on the mesophile bacteria and fungi/yeast populations were analyzed. The results showed total Pb concentrations up to 647 ± 3.50 mg/kg, a 46% bioaccessible fraction (297 ± 9.90 mg/kg) in the gastric phase and a 12.2% (80 ± 5 mg/kg) bioaccessible fraction in the intestinal phase, indicating a health and environmental risk. Meanwhile, the geochemical fractionation before washing showed a Pb fraction mainly consisting of Fe/Mn oxy-hydroxides (69.6%); this reducible fraction may progressively increase its bioaccessibility. Geochemical fractionation performed in the washed soil showed differences from that determined before the treatment; however, the iron and manganese fraction, at 42.4%, accounted for most of the Pb. The soil microbiology was also modified by EDTA, with an increase in aerobic bacteria and a decrease in fungi/yeast populations. Although 44% total lead removal was achieved, corresponding to a final concentration of 363.50 ± 43.50 mg/kg (below national and USEPA standards), washing with EDTA increased the soluble and interchangeable lead concentrations. Statistical analysis indicated a significant effect (p < 0.05) of EDTA on the soil's geochemical fractionation of lead.

Nickel and copper accumulation strategies in Odontarrhena obovata growing on copper smelter-influenced and non-influenced serpentine soils: a comparative field study.

The present investigation is the first in situ comparative study for the identification of Ni and Cu accumulation strategies involved in Odontarrhena obovata (syn. Alyssum obovatum (C.A. Mey.) Turcz.) growing in Cu-rich smelter-influenced (CSI) and non-Cu-influenced (NCI) sites. The total and Na2EDTA (disodium ethylenediaminetetraacetic acid)-extractable metal concentration in soils and plant tissues (roots, stem, leaves and flowers) were determined for CSI and NCI sites. High concentrations of total Ni, Cr, Co and Mg in the soil suggest serpentine nature of both the sites. In spite of high total and extractable Cu concentrations in CSI soil, majority of its accumulation was restricted to O. obovata roots showing its excluder response. Since the translocation and bioconcentration factors of Ni > 1 and the foliar Ni concentration > 1000 µg g-1, it can be assumed that O. obovata has Ni hyperaccumulation potential for both the sites. No significant differences in chlorophyll content in O. obovata leaves were observed between studied sites, suggesting higher tolerance of this species under prolonged heavy metal stress. Furthermore, this species from CSI site demonstrated rather high viability under extreme technogenic conditions due to active formation of antioxidants such as ascorbate, free proline and protein thiols. The presence of Cu in higher concentration in serpentine soil does not exert detrimental effect on O. obovata and its Ni hyperaccumulation ability. Thus, O. obovata could act as a putative plant species for the remediation of Cu-rich/influenced serpentine soils without compromising its Ni content and vitality.

Strontium accumulation by the terrestrial and aquatic plants affected by mining and municipal wastewaters (Elazig, Turkey).

The mining and municipal wastewaters in the study area are located around Elazig, Turkey. This study investigated the translocation and accumulation of Sr into 9 terrestrial-aquatic plants from the Elazig municipal wastewater, Keban Pb-Zn and Maden Cu wastewaters. Plants and their soil samples were collected from the stream/rivers on the municipal and mining areas, and Sr values in both plant parts and their soils were analyzed by ICP-MS. The mean Sr concentrations in the soil, root and shoot of the terrestrial-aquatic plants were 101, 48.2 and 80.5 ppm, respectively (on the dried weight basis). The enrichment coefficients of root (ECR) and shoots (ECS) and translocation factors of studied plants were calculated and, then, divided into several groups as a candidate, bioaccumulator and hyperaccumulator plants according to their ECR and ECSs. These groups indicated the candidate plants: Salix sp. and Tamarix tetrandra; bioaccumulator plants: Pragmites sp. and Xanthium, and hyperaccumulator plants: Typha latifolia, Bolboscholnus ascbersus and Lythnium salicaria for Sr. These results showed that both bioaccumulator and hyperaccumulator plant groups had very high ability to accumulate strontium to plant parts from their soil. Therefore, these studied plants may be helpful/useful for the rehabilitation studies of municipal and mining soils contaminated by Sr.

The migration of cadmium and lead in soil columns and their bioaccumulation in a multi-species soil system.

A soil microcosm experiment was carried out to quantify the transfer of cadmium (Cd) and lead (Pb) in a multi-species soil system (MS·3). Red earth from Jiangxi (S1), fluvo-aquic soil from Henan (S2), fluvo-aquic soil from Beijing (S3), and black soil from Heilongjiang (S4) were used for soil column packing with S1, S3, or S4 as the 20-50 cm layer and S2, which was Cd- and Pb-contaminated, as the top 0-20 cm layer. For each soil combination, four treatments were set up: CK (no wheat and no earthworm), W (only wheat), E (only earthworm), and E + W (earthworm and wheat). The results showed that the coexistence of earthworm with wheat reduced Cd and Pb contents in wheat plants and earthworms, and increased plant biomass, but had no significant effect on the survival rate and mean weight change rate of earthworms. Total Cd and Pb decreased remarkably in the 0-20 cm layer while increased in the 20-50 cm layer, and approximately 32.8%-51.1% of Cd and 0.35%-7.0% of Pb migrated down into the 20-50 cm soil layers from the 0-20 cm soil layers. The migration varied between the treatments from S2 to S1, S2, and S3. In S2-S1 and S2-S4 columns, the amount of Cd migration decreased when the earthworms coexisted with wheat, while in S2-S3 column, there was no significant difference on such amount regardless of the coexistence of earthworms with wheat. Taken together, the results indicated that the migration of Cd and Pb was not only associated with wheat and earthworm, but also depended on soil types.

Uptake, accumulation, and translocation mechanisms of steroid estrogens in plants.

Applying sewage sludge or animal manure onto agricultural land can result in estrogen pollution, which increases the risk of human exposure to steroid estrogens (SEs) via the food chain. However, the uptake and accumulation mechanism of SEs by plants is still unclear. In this study, the uptake, accumulation, and translocation of 17ß-E2, a representative SE, were investigated through a series of wheat hydroponic experiments. Various inhibitors were applied to explore the uptake pathways of 17ß-E2 by wheat. In addition, the effects of exposure concentrations, coexisting 17α-ethynylestradiol (EE2) and plant properties on the uptake of 17ß-E2 were examined. The results indicated that the accumulation of 17ß-E2 in wheat roots mainly resulted from adsorption and active uptake that involved aquaporins and anion channels transport. The chlorophyll and protein contents of plants were positively correlated with the uptake of 17ß-E2, whereas competitive inhibition occurred when 17ß-E2 and EE2 coexisted in the same solution. Nevertheless, the results of a split-root experiment showed that 17ß-E2 absorbed by wheat could further migrate in plant via long-distance transport and ultimately was discharged from plants, suggesting that 17ß-E2 was still at risk of being released even though it had been absorbed by plants. These results could provide valuable insights into the risk assessment and risk control of the uptake of SEs by plants.