Highest Bioconcentration Factor Research Articles

Phytoavailability and transfer of mercury in soil-pepper system: Influencing factors, fate, and predictive approach for effective management of metal-impacted spiked soils

Mercury (Hg) contamination and accumulation in food crops is a global threat posing potential health risk to humans. However, Hg phytoavailability in soil-pepper system and its influencing factors largely remain unknown. In this study, a greenhouse pot experiment was conducted to grow peppers using 21 Chinese agricultural soils with varied soil properties and aged Hg levels. Mercury concentration in pepper leaves and fruits ranged from 0.021 to 0.057 mg kg−1 and 0.005–0.022 mg kg−1 respectively, while fruit Hg content in three soils (Anhui, Hubei, Beijing) exceeded the safety limit. Fruit Hg concentration was better positively correlated with soil Mg(NO3)2-extractable Hg content (r = 0.7, P < 0.0001) than soil total Hg content (r = 0.45, P < 0.0001). Highest bioconcentration factor (BCF, ratio of Hg plant to Hg soil) yielded in acidic soils, while the lowest BCF occurred in alkaline soils. Path analysis indicated available-Hg (R2 = 0.40) and total-Hg (R2 = 0.40) had direct positive effects on the pepper fruit Hg concentration, while direct negative effects including pH (R2 = −0.86), organic matter (R2 = −0.7), crystalline-Fe (R2 = −0.68). Those agreed with the stepwise multiple linear regression analysis which yielded a regression predictive model (R2 = 0.73, P < 0.0001). Soil available-Hg, total-Hg, pH, organic matter and crystalline-Fe & Mn were the most influencing factors of Hg phytoavailability. These results provide new insights into the phytoavailability of Hg in soil-pepper system, thus facilitating the management of pepper cultivation in Hg-enriched soils.

Early developmental nanoplastics exposure disturbs circadian rhythms associated with stress resistance decline and modulated by DAF-16 and PRDX-2 in C. elegans

Plastics pollution is an emerging environmental problem and nanoplastics (NPs) toxicity has received great concern. This study investigated whether early developmental exposure to polystyrene NPs influence the circadian rhythms and the possible underlying mechanisms in C. elegans. We show that early developmental NPs exposure disturbs circadian rhythms in C. elegans and ASH neurons and G protein-coupled receptor kinase (GRK-2) are involved in the level of chemotaxis response. A higher bioconcentration factor in entrained worms was observed, suggesting that circadian interference results in increased NPs bioaccumulation in C. elegans. In addition, we show that reactive oxygen species produced by NPs exposure and peroxiredoxin-2 (PRDX-2) are related to the disturbed circadian rhythms. We further show that the NPs-induced circadian rhythms disruption is associated with stress resistance decline and modulated by transcription DAF-16/FOXO signaling. Because circadian rhythms are found in most living organisms and the fact that DAF-16 and PRDX-2 are evolutionarily conserved, our findings suggest a possible negative impact of NPs on circadian rhythms and stress resistance in higher organisms including humans.

Study on the environmental fate of three insecticides in garlic by in vivo sampling rate calibrated-solid phase microextraction-gas chromatography-mass spectrometry

Traditional sample preparation methods for insecticide analysis are laborious and fatal to living organisms. In the work, an in vivo sampling rate calibrated-solid phase microextraction-gas chromatography-mass spectrometry method was established and successfully used for in vivo sampling and quantitative determination of three insecticides (hexachlorobenzene, fipronil and chlorfenapyr) by direct exposing micron-sized fiber in living garlic. Absorption, enrichment, migration and elimination behavior of insecticides in garlic were investigated. Bioaccumulative effects with obvious tissue differences were observed to all three insecticides, especially for chlorfenapyr. Bioconcentration factors (BCFs) ranging from 0.0342 to 1.0887 were obtained, and the closer to roots, the higher BCFs. The half-life of insecticides in garlic ranged from 0.43 to 0.96 d. In the first 24 h, 55.0% − 80.3% insecticides residues in garlic were eliminated with first-order elimination kinetics. The research provides in vivo insights into the environmental fates of insecticides in complex living system with minimized organism damage.

Bioavailability and toxicity variation of benzo(a)pyrene in three soil–wheat systems: Indicators of soil quality

AbstractBenzo(a)pyrene [B(a)P] as a representative polycyclic aromatic hydrocarbons (PAHs) is of worldwide i interest and widely studied in various fields. However, biological and biochemical actions of B(a)P in soil–wheat systems are still rarely reported. In view of the fact that the contents of B[a]P as a ubiquitous soil pollutant in the environment varies greatly, in our study at the laboratory‐scale we explored control factors and aimed to increase basic knowledge of its variations and effects on soil–wheat systems. We studied this for different soil types (red, black, and brown) and for soils newly artificially contaminated (at rates of 0.1, 1, and 10 mg kg−1), to provide some references for complicated 'real' cases. The bioavailability (extractability and bioaccumulation) and basic biological toxicity were tested. Results showed that B(a)P concentrations in soil–wheat (Tritticum aestivum L.) systems extracted by HPCD were insignificantly (p &gt; 0.05) higher than Tenax‐TA, and varied with soil types and spiked concentrations. Also, the root and shoot length were mostly inhibited from 0.88% to 26.35%, and 5.46% to 54.85%, respectively, by B(a)P in different soil types and increased with its increasing concentration. Comparatively, higher bioconcentration factor and translocation factor values were observed under lower group in red soil–wheat systems, and under higher added groups in black and brown soil–wheat systems. Moreover, inhibitive effects posed by B(a)P were mainly targeted at wheat shoots in these soils. This study provided a knowledge of B(a)P in ecosystems with different soil types and specific plant species, further to serve for soil environmental protection with many variations.

An Integrated Strategy for Purification by Combining Solid-Phase Extraction with Dispersive-Solid-Phase Extraction for Detecting 22 Pesticides and Metabolite Residues in Fish.

A robust isotope-labeled internal standard method was established for the detection of 22 pesticides and metabolite residues in four kinds of fish; two were from freshwater fish, and two were from marine fish. Pesticides with wide application possibilities in rice in China, strong leaching to water, or high bioconcentration factors (BCF) in fish were selected. The samples were extracted with 1% acetic acid-99% acetonitrile. The extracts were first purified by solid-phase extraction (PEP-plus), cleaned with dispersive-solid-phase extraction (PSA and C18), and finally analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results showed that good linearities for the target compounds were observed in the range of 0.1-100 ng/mL, and the correlation coefficient (R2) of each compound was greater than 0.99. The recoveries of the method were within 70-120% with RSDs <20% at three different spiked concentration levels (0.5, 5, and 100 ng/g). The quantitative limit of the method was 0.5-5 ng/g. The method is shown to be sensitive and accurate and can meet the demands for the quantitative analysis of pesticides in fish.

Fractionation and Distribution of Rare Earth Elements in Marine Sediment and Bioavailability in Avicennia marina in Central Red Sea Mangrove Ecosystems.

Rare earth element fractionation and distribution in the coastal ecosystem have been of significant concern and are recognized worldwide as emerging micro-pollutants. However, unlike other metals such as trace elements, little is known about their uptake by aquatic plants such as the mangrove Avicennia marina, especially in the central Red Sea. We investigated the fractionation of rare earth elements in six mangrove ecosystems in the central Red Sea and bioavailability in mangrove A. marina. The concentrations of rare earth elements, sediment grain sizes, multi-elemental ratios, geo-accumulation index (Igeo) and bioconcentration factor (BCF) vary significantly (p < 0.05) across the six mangrove ecosystems. Higher concentrations of rare earth elements were recorded at Al Lith (LT) (101.53 mg/kg) and South Jeddah (SJ) (73.38 mg/kg) mangrove ecosystems. However, multi-elemental ratio R(M/L) reveals positive values. In contrast, multi-elemental ratio R(H/M) reveals negative values corresponding to fractionation patterns enriched with medium rare earth elements and heavy rare earth elements depletion across the six mangrove ecosystems. BCF values for rare earth elements were <1, but Lutetium (0.32) had the highest BCF among the rare earth elements, suggesting an efficient accumulation of Lutetium than any other rare earth elements. The scale of Igeo revealed strong contamination (4 ≤ Igeo ≥ 5) of sediment with Lanthanum, Cerium, Praseodynium, Samarium, Godolinium, Holmium, Erbium, Ytterbium, and moderate contamination with Thulium, Terbium, and Dysprosium (1 ≤ Igeo ≤ 3). Principal component analysis showed that clay silt sediment grain size influences rare earth element concentrations in the central Red Sea. Our results provide new evidence for rare earth element fractionation and accumulation in sediment and the potential use of mangrove A. marina for rare earth element monitoring in mangrove ecosystems in the central Red Sea.

Lability and bioavailability of Co, Fe, Pb, U and Zn in a uranium mining restoration site using DGT and phytoscreening.

Mine restoration is a long and ongoing process, requiring careful management, which must be informed by site-specific, geochemical risk assessment. Paired topsoil and tree core samples from 4 sites within the uranium mining complex of INB Caldas in Minas Gerais (Brazil) were collected. Soil samples were analysed for their total content of Co, Fe, Pb, U and Zn by XRF, and subsequently, the potential environmental bioavailability of these metals were investigated by DGT and pore water analysis. In addition, results were compared with metal concentrations obtained by Tree Coring from the forest vegetation. In all sampling areas, mean total concentrations of U (Ctot. = 100.5 ± 66.5 to 129.6 ± 57.1 mg kg-1), Pb (Ctot. = 30.8 ± 12.7 to 90.8 ± 90.8 mg kg-1), Zn (Ctot. = 91.5 ± 24.7 to 99.6 ± 10.3 mg kg-1) and Co (Ctot. = 73.8 ± 25.5 to 119.7 ± 26.4 mg kg-1) in soils exceeded respective quality reference values. Study results suggest that AMD caused the increase of labile concentrations of Zn in affected soils. The high lability of the elements Pb (R = 62 ± 34 to 81 ± 29%), U (R = 57 ± 20 to 77 ± 28%) and Zn (R = 21 ± 25 to 34 ± 31%) in soils together with high bioconcentration factors found in wood samples for Pb (BCF = 0.0004 ± 0.0003 to 0.0026 ± 0.0033) and Zn (BCF = 0.012 ± 0.013 to 0.025 ± 0.021) indicated a high toxic potential of these elements to the biota in the soils of the study site. The combination of pore water and DGT analysis with Tree Coring showed to be a useful approach to specify the risk of metal polluted soils. However, the comparison of the results from DGT and Tree Coring could not predict the uptake of metals into the xylems of the sampled tree individuals.

Heavy metals concentration in vegetables irrigated with municipal wastewater and their human daily intake in Erbil city

Assessment of heavy metals accumulation in vegetables and their levels in human is vital in countries where wastewater is used for irrigation. In this study, The aim of this research was to investigate the concentrations of highly toxic metals such as Nickel (Ni), chrome (Cr), lead (Pb), zinc (Zn), cadmium (Cd), and copper (Cu) in wastewater, farmlands soils and vegetables (chard, celery, cress and leek), and also their possible human health risk in the area of Erbil city. The heavy metals concentration in the vegetable, soil and water samples were analyzed by using an atomic absorption spectrophotometer. Bio-concentration factor (BCF), daily intake (DI) and health risk index (HRI) were calculated in order to estimate the human health risk. Overall, results indicated that the water, soil and vegetable samples were contaminated with Ni, Cd, Cr, Cu, Pb, and Zn. The trends of these metals concentrations were as follows: 0.613 > 0.316 > 0.162 > 0.065 > 0.041 > 0.028 mL/L for Ni, Cd, Pb, Cr, Cu, and Zn, respectively in the wastewater and 189.09 > 125 > 104.92 > 41.85 > 28.58 > 21.72 for Zn, Cr, Ni, Pb, Cu and Cd mgkg−1 in the soil. The mean concentrations (mg kg−1) in the vegetable samples ranged from 22.74 to 30.30, 5.18–9.19, 29.50–33.87, 39.42–64.78, 7.87–11.83 and 77.68–117.98 for Ni, Cd, Pb, Cr, Cu and Zn, respectively. In addition, the calculated BCFs value ranged from 0.21 to 71.295, with Pb having the highest BCF. The calculated DI for Ni, Cd and Pb exceeded WHO/FAW safe limits for adult and children. Furthermore, the HRI values of Cd and Pb exceeded the safe limit (1) for both adults and children, but the values for Ni (> 1) exceeded the safe limit only for children. These findings clearly indicate that the practice of irrigating the vegetables with untreated wastewater by local farmers have caused high accumulation of heavy metals in the soils and vegetables which are posing health risk to the population in the vicinity. Therefore, regular monitoring of these metals in the wastewater-irrigated vegetables is necessary.

Chromium accumulation in soil, water and forage samples in automobile emission area.

Environmental contamination caused by various pollutants due to automobile emissions is an alarming issue. One important type of the pollutants are heavy metals, including chromium (Cr) added by the exhaust of toxic smoke of vehicles. These pollutants are added to forage crops cultivated near roadsides, soil and irrigation water. However, rare studies have been conducted to infer Cr accumulation near heavy automobile emission areas. This study was conducted to determine Cr concentration in irrigation water, soil and forage. Water, forage and soil samples were collected from area impacted by heavy traffic. Atomic absorption spectrophotometer was used to appraise Cr values in the collected samples. Chromium values ranged from 0.50 to 1.14 mg/kg in water samples and from 0.04 to 2.23 mg/kg in soil samples. It was highest in Zea mays grown soil, whereas minimum in Brassica campestris soil. The Cr values in forages ranged from 0.09 to 1.06 mg/kg. Z. mays observed the highest Cr accumulation, whereas the lowest Cr accrual was noted for B. campestris. The pollution load index (PLI) was the highest for Trifolium alexandrinum, while the lowest for Z. mays. Bio-concentration factor (BCF) ranged from 0.14 to 8.63. The highest BCF was noted for T. alexandrinum, while the lowest for Z. mays. The highest and the lowest daily intake of metal (DIM) was noted for Z. mays at different sites. Health risk index (HRI) was highest for Z. mays and lowest for B. campestris. The results add valuable information on heavy metal accumulation in water, soil and forage samples near to automobile emission area.

Growth Responses and Accumulation Characteristics of Three Ornamental Plants to Sn Contamination in Soil

Decorative ornamental plants have been applied as hyperaccumulators/phytoremediators to a wide spectrum of heavy metal contaminants. In this study, pot culture experiments were conducted to investigate the Sn tolerance and accumulation in Impatiens balsamina L., Mirabilis jalapa L. and Tagetes erecta L., in order to assess the possibility of these three ornamental plants to be used as phytoremediators of Sn-contaminated soil. Results show that all three plants exhibited strong tolerance to Sn contamination, and no significant visual toxicity was observed for all three plants grown under most of the Sn treatments. The amount of Sn accumulated in the three plants was positively correlated with the Sn concentration in the soil. The order of the Sn accumulative capacity was Impatiens balsamina &gt; Mirabilis jalapa &gt; Tagetes erecta. Impatiens balsamina and Tagetes erecta showed a low translocation ability (TF) (&lt;1), and the roots accumulated the highest Sn concentration, but Impatiens balsamina showed a relatively high bioconcentration factor (BCF, Sn concentration in each part &gt; 100 mg/kg after Sn treatment of 500 mg/kg). Meanwhile, the TF of Mirabilis jalapa was &gt;1, and the fluorescence accumulated the most Sn. In combination with the adaptation to high concentrations of various heavy metals, these three ornamental plants are potential candidates for Sn mining tailings or contaminated soil.

Toxic metals distribution, seasonal variations and environmental risk assessment in surficial sediment and mangrove plants (A. marina), Gulf of Kachchh (India)

Toxic metal pollution in the coastal ecosystem is becoming a serious problem, particularly in developing countries as a result of the industrial revolution. In recent years, mangroves are continuously contaminating with toxic metals and receiving global attention due to its toxicity, non-degradability, abundance, subsequent bioaccumulation, and biomagnification through successive trophic levels. This study aims to investigate the toxic metal content and pollution status in mangroves surface sediment and plants. Results showed that toxic metals in sediments were higher than natural background levels indicate anthropogenic sources. Fe, Mn, Sb, Ti found higher in concentration among all toxic metals, and site 9, 15, 18, 19, 21, 31 found the highest total metal load. Contamination indices like enrichment and contamination factor, geo-accumulation index, suggest minimal to extremely high level of contamination, and sediments have found extremely contaminated with Sb and As. Contamination degree and modified contamination degree suggest very high degree of contamination at all sites. Pollution load index indicates significant deterioration of sediment quality. Ecological risk and potential ecological risk index also indicate about 72% of sites come under higher ecological risk. Toxic metal in Avicennia marina was found higher in root than leaf. High bioconcentration factor has observed for Pb, Cu, Mo, Zn. Translocation factor for Cu and Zn at all sites, and As, Ni, Pb, Fe, Sr, Mn at some sites indicate high-efficiency in plants for toxic metal translocation.

Translocation of heavy metals in medicinally important herbal plants growing on complex organometallic sludge of sugarcane molasses-based distillery waste

This study aimed to assess the heavy metals accumulation patterns by some native plants such as Achyranthus aspera L., Amaranthus viridis, Basella alba L., Sesbania bispinosa, Pedalium murex L., and Momordica doica, which have been traditionally employed for medicinal and food purposes. The plants were grown on complex distillery waste containing a mixture of organometallic compounds. Results revealed bioaccumulation of Mn, Cd, Fe, Cr, Cu, As, Se, Mo, and Co in their roots, shoots, and leaves in levels higher than the surrounding sludge. A. aspera was noted as root accumulator for Mn (16.95 mg kg−1), Zn (30.12 mg kg−1), Fe (240.40 mg kg−1), Co (3.19 mg kg−1), while Se (4.07 mg kg−1), Mo (4.36 mg kg−1), was accumulated selectively in the shoot of the plant. Similarly, S. bispinosa, P. murex, and M. doica were found as root accumulators for Mn, Fe, and Ni. A. viridis accumulated Cd, Zn, and Cu in the shoot and leaves of the plant. The high bioconcentration factors (BCF) and translocation factors (TF) observed in these native plants (>1) suggested their tendency to hyperaccumulate heavy metals. The findings highlighted that these plants as a potential metal accumulator may pose health hazards and deteriorate the medicinal property if grown on such wastes.

The potential of Blepharidium guatemalense for nickel agromining in Mexico and Central America

The aim of this study was to assess the potential of the woody nickel hyperaccumulator species Blepharidium guatemalense (Standl.) Standl. for agromining in southeastern Mexico. Pot trials consisting of nickel dosing (0, 20, 50, 100, and 250 mg Ni kg−1), and synthetic and organic fertilization were conducted. Field trials were also undertaken with different harvesting regimes of B. guatemalense. Foliar nickel concentrations increased significantly with rising nickel additions, with a 300-fold increase at 250 mg Ni kg−1 treatment relative to the control. Synthetic fertilization strongly increased nickel uptake without any change in plant growth or biomass, whereas organic fertilization enhanced plant shoot biomass with a negligible effect on foliar nickel concentrations. A 5-year-old stand which was subsequently harvested twice per year produced the maximum nickel yield tree−1 yr−1, with an estimated total nickel yield of 142 kg ha−1 yr−1. Blepharidium guatemalense is a prime candidate for nickel agromining on account of its high foliar Ni concentrations, high bioconcentration (180) and translocation factors (3.3), fast growth rate and high shoot biomass production. Future studies are needed to test the outcomes of the pot trials in the field. Extensive geochemical studies are needed to identify potential viable agromining locations. Novelty Statement Our research team is a pioneer in the discovery of metal hyperaccumulator plants in Mesoamerica with at least 13 species discovered in the last 2 years. This study is the first to assess the potential of nickel agromining (phytomining) in Mexico (and in all the American continent), using one of the strongest nickel hyperaccumulators reported so far. The promising results of this study are the basis for optimal agricultural management of Blepharidium guatemalense.

In-site and Ex-site Date Palm Exposure to Heavy Metals Involved Infra-Individual Biomarkers Upregulation.

As a tree of considerable importance in arid regions—date palm, Phoenix dactylifera L. survival in contaminated areas of Sfax city has drawn our attention. Leaf samples of the plants grown in the study area showed high levels of cadmium (Cd), copper (Cu), and chromium (Cr). On the basis of this finding, the cellular mechanisms that explain these metal accumulations were investigated in controlled conditions. After four months of exposure to Cd, Cr, or Cu, high bioconcentration and translocation factor (TF > 1) have been shown for date palm plantlets exposed to Cd and low TF values were obtained for plantlets treated with Cr and Cu. Moreover, accumulation of oxidants and antioxidant enzyme activities occurred in exposed roots to Cu and Cd. Secondary metabolites, such as polyphenols and flavonoids, were enhanced in plants exposed at low metal concentrations and declined thereafter. Accumulation of flavonoids in cells may be correlated with the expression of the gene encoding Pdmate5, responsible for the transport of secondary metabolites, especially flavonoids. Other transporter genes responded positively to metal incorporation, especially Pdhma2, but also Pdabcc and Pdnramp6. The latter would be a new candidate gene sensitive to metallic stress in plants. Expressions of gene coding metal chelators were also investigated. Pdpcs1 and Pdmt3 exhibited a strong induction in plants exposed to Cr. These modifications of the expression of some biochemical and molecular based-markers in date palm helped to better understand the ability of the plant to tolerate metals. They could be useful in assessing heavy metal contaminations in polluted soils and may improve accumulation capacity of other plants.

Heavy metal pollution assessment in coastal sediments and bioaccumulation on seagrass (Enhalus acoroides) of Palau

Heavy metals in coastal sediments and seagrass (Enhalus acoroides) were studied to assess the pollution level and to understand the bioaccumulation of metals on different organs. The mean of metal concentrations in sediments were in the following order: Cr > Ni > As>Zn > Cu > Co > Pb > Cd > Hg. The results of principal component analysis indicate that Cr, Ni, Cu, Zn, As and Hg are derived from natural sources but Cd and Pb seems to be of anthropogenic sources. Cr, Ni, Cu, Zn, Cd and Pb in the coastal sediments were at low ecological risk level. As and Hg presented the highest ecological risk among all metals. The mean concentrations of Cr, Ni, Cu, Zn, Cd, and Hg were higher in leaves of E. acoroides than in roots. Significant correlations (p < 0.05) for Cr, Ni, Cu, Zn, and Pb in between sediments and in E. acoroides both leaves and roots. High bioconcentration factor (BCF) were calculated for Zn, Cd, and Hg.

TiO2 nanoparticles enhanced bioaccumulation and toxic performance of PAHs via trophic transfer

Engineering nanoparticles (NPs) could act as accumulator and carrier of co-contaminants, affecting their fate and toxicity in environments. However, the effects of NPs on the bioaccumulation and trophic transfer of co-contaminants through the food chain and the ensuing effects on higher predators are unclear. In the present study, we investigated the effects of titanium dioxide nanoparticles (nTiO2) on the trophic transfer of phenanthrene (Phe) from prey Artemia salina to predator Scophthalmus maximus. We also evaluated the ensuing toxic performance of Phe in S. maximus after been transferred from A. salina in the presence and absence of nTiO2. The presence of nTiO2 significantly (p < 0.05) increased Phe accumulation in A. salina with higher bioconcentration factor (BCF) up to 90.9 than that of 38.6 in Phe exposure along. After trophic transfer, nTiO2 (1 mg/L) also promoted the bioaccumulation of Phe (1 μg/L) in predator S. maximus from 4.17 mg/kg to 7.85 mg/kg (dry weight). However, nTiO2 did not enhance the trophic transfer of Phe from A. salina to S. maximus since the biological magnification factor (BMF) decreased from 0.13 to 0.08. Nevertheless, the nTiO2-enhanced bioaccumulation of Phe did enhance Phe toxicity performance in predator S. maximus after trophic transfer, showing significant (p < 0.05) growth inhibition and changes of nutrient status in the predator, compared to those of the control. Further physio-biochemical investigations suggested that oxidative stress and inhibition of digestive functions might explain the growth inhibition in treatment with nTiO2 + Phe. This study demonstrates the first evidence that NP-enhanced bioaccumulation and toxic performance of co-existing pollutants across trophic transfer, which poses potential risks to marine ecosystems, and ultimately human health by seafood consumption.

Water contamination with atrazine: is nitric oxide able to improve Pistia stratiotes phytoremediation capacity?

Atrazine is an herbicide commonly used in several countries. Due to its long half-life, associated with its use in large scales, atrazine residues remain as environmental pollutants in water bodies. Phytoremediation is often pointed out as an interesting approach to remove atrazine from the aquatic environment, but its practical application is limited by the high toxicity of this herbicide. Here, we characterize the damages triggered by atrazine in Pistia stratiotes, evaluating the role of nitric oxide (NO), a cell-signaling molecule, in increasing the tolerance to the pollutant and the phytoremediation potential of this species. Pistia stratiotes plants were exposed to four treatments: Control; Sodium nitroprusside (SNP) (0.05mgL-1); Atrazine (ATZ) (150μgL-1) and ATZ+SNP. The plants remained under those conditions for 24h for biochemical and physiological analysis and 3 days for the evaluation of relative growth rate. The presence of atrazine in plant cells triggered a series of biochemical and physiological damages, such as the increase in the generation of reactive oxygen species, damages to cell membranes, photosynthesis impairment, and negative carbon balance. Despite this, the plants maintained greater growth rates than other aquatic macrophytes exposed to atrazine and showed high bioconcentration and translocation factors. The addition of SNP, a NO donor, decreased the herbicide toxicity, with an increase of over 60% in the IC50 value (Inhibitor Concentration). Indeed, the NO signaling action was able to increase the tolerance of plants to atrazine, which resulted in increments in pollutant uptake and translocation, with the maintenance of overall cell (e.g. membranes) and organs (root system) structure, and the functioning of central physiological processes (e.g. photosynthesis). These factors allowed for more quickly and efficient removal of the pollutant from the environment, reducing costs, and increasing the viability of the phytoremediation process.

Uptake and translocation of multiresidue industrial and household contaminants in radish grown under controlled conditions

The uptake, bioconcentration and translocation of 22 endocrine disrupting compounds (six perflurocarboxylic acids (PFAAs), perfluorooctanoic sulfonic acid, four anionic surfactants (alkylsulfates (ASC) from C12 to C16), bisphenol A (BPA), four preservatives (parabens), two biocides (triclosan (TCS) and triclocarban (TCB)) and five UV-filters (benzophenones)) in radish (Raphanus sativus) has been investigated. Radishes were grown in sewage sludge-amended soil under controlled conditions in a grown chamber. Degradation in soil adhered to root was higher than in soil and varied significantly from a family to another. The most recalcitrant compounds were PFCs, anionic surfactants and TCB. Perfluorinated compounds and AS-C12 were detected in all plant tissues and were the compounds with the highest bioconcentration factors (BCF). A decrease of BCF was observed for ASCs with the increase of the alkyl chain. Non-ionic compounds, except TCB, were mainly accumulated in bulb. Phenolic compounds were detected at lower concentration levels than non-phenolic compounds probably due to metabolisation in radish cells. The highest BCF in edible bulb were obtained for PFOS (BCF: 1.668), perfluorooctanoic acid (BCF: 0.534) and AS-C12 (BCF: 0.523). This study reports for the first-time multiresidue plant uptake and translocation of pollutants from different chemical classes (perfluorinated compounds, surfactants, plasticiser, preservatives, biocides and UV-filters) and with a wide variety of physical-chemical properties.

Impact of long-term irrigation with municipal reclaimed wastewater on the uptake and degradation of organic contaminants in lettuce and leek

A two years drip irrigation of lettuce and leek crops with treated municipal wastewater without and with spiking with fourteen wastewater relevant contaminants at 10 μg/L concentration level was conducted under greenhouse cultivation conditions to investigate their potential accumulation in soil and leaves and to assess human health related risks. Lettuce and leek crops were selected as a worse-case scenario since leafy green vegetable has a high potential for organic contaminants uptake. The results revealed limited accumulation of contaminants in soil and plant leaves, their concentration levels being in the range of 1–30 ng/g and 1–660 ng/g range in soil and leaves, respectively. This was likely related to abiotic and biotic transformation or simply binding processes in soil, which limited contaminants plant uptake. This assumption was underpinned by studies of the enantiomeric fractionation of chiral compounds (e.g. climbazole and metoprolol) in soil as pieces of evidence of biodegradation and by the identification of transformation products or metabolites in leaves by means of liquid chromatography - high resolution - mass spectrometry using a suspect screening workflow. The high bioconcentration factors were not limited to compounds with intermediate Dow (100 to 1000) such as carbamazepine but also observed for hydrophilic compounds such as clarithromycin, hydrochlorothiazide and the food additives acesulfame and sucralose. This result assumed that accumulation was not only driven by passive processes (e.g. lipoidal diffusion through lipid bilayer cell membranes or Casparian strip) but might be supported by carrier-mediated transporters. As a whole, this study confirmed earlier reports on the a de minimis human health risk related to the consumption of raw leafy green vegetable irrigated with domestic TWW containing organic contaminants residues.

Ecotoxicity of pesticides and semiochemicals used for control and prevention of conifer bark beetle (Dendroctonus spp.) outbreaks

Application of pyrethroid pesticides and semiochemicals are two treatments used worldwide to control conifer bark beetles (Dendroctonus spp.); their residues can reach water reservoirs and water currents through run off and affect non-target organisms such as freshwater invertebrates. Therefore, we assessed the 48-h lethal toxicity, chronic toxicity (reproduction inhibition), and bioaccumulation of three pyrethroid pesticides (bifenthrin, cypermethrin, and deltamethrin) and two semiochemicals (verbenone and 3-methyl-2-cyclohexen-1-one) in two freshwater invertebrates: the cladoceran Alona guttata and the rotifer Lecane papuana. Bifenthrin was the most toxic of the five chemical compounds tested followed by deltamethrin and then cypermethrin, which was the least toxic pyrethroid for both species. Semiochemicals were far less toxic than pyrethroids and verbenone was most toxic than 3-methyl-2-cyclohexen-1-one for both species. For the rotifer Lecane papuana, the pyrethroid with the highest Bioconcentration Factor was bifenthrin, and for the semiochemicals it was 3-methyl-2-cyclohexen-1-one. For the cladoceran Alona guttata, the pyrethroid with the highest bioconcentration factor was cypermethrin and for the semiochemicals it was verbenone. The pyrethroid with highest body burdens both lethal and chronic was cypermethrin. Semiochemicals showed lethal and chronic body burdens 12-fold higher than pyrethroids and were therefore less toxic than pyrethroids. These results showed that the semiochemicals verbenone and 3-methyl-2-cyclohexen-1-one are a safe tool for the freshwater invertebrates tested when compared with pyrethroid pesticides. Cypermethrin was the least toxic of the pyrethroids tested and therefore could be considered as a good candidate to control outbreaks of the conifer bark beetle.