peer reviewed | Microplastics (MPs) are thought to be ingested by a wide range of marine organisms before being excreted. However, several studies in marine organisms from different taxa have shown that MPs and nanoplastics could be translocated in other organs. In this study, we investigated the presence of MPs in the livers of commercial zooplanktivorous fishes collected in the field. The study focuses mainly on the European anchovy Engraulis encrasicolus but concerns also the European pilchard Sardina pilchardus and the Atlantic herring Clupea harengus. Two complementary methodologies were used to attest the occurrence of MPs in the hepatic tissue and to exclude contamination. 1) MPs were isolated by degradation of the hepatic tissue. 2) Cryosections were made on the livers and observed in polarized light microscopy. Both methods separately revealed that MPs, mainly polyethylene (PE), were translocated into the livers of the three clupeid species. In anchovy, 80 per cent of livers contained relatively large MPs that ranged from 124 μm to 438 μm, showing a high level of contamination. Two translocation pathways are hypothesized: (i) large particles found in the liver resulted from the agglomeration of smaller pieces, and/or (ii) they simply pass through the intestinal barrier. Further studies are however required to understand the exact process. © 2017 Elsevier Ltd

To evaluate the influence of surface coatings on nano-fertilizers uptake and their phytotoxicity to crops and its health risk to Chinese adults, trisodium citrate (TC) and polyethylene glycol (PEG) coatings were prepared on the surface of copper oxide nanoparticles (CuO NPs), respectively, with 100 and 500 mg/L of bare CuO NPs, TC-CuO NPs, and PEG-CuO NPs were exposed to soil-grown Ipomoea aquatica Forssk. Combined bio-transmission electron microscopy and micro-CT observed cellular migration of coated CuO NPs in symplastic and apoplastic pathways, as well as nanoparticles transported through vascular tissues to the above-ground parts. Since TC-CuO NPs had less inhibition on vascular phylogeny of I. aquatica roots which was determined by RT-qPCR, their migration in plants was more efficient, thus exhibiting greater phytotoxicity to shoots. Meanwhile, coatings significantly reduced the phytotoxicity of CuO NPs by stimulating plant antioxidant defense. The risk of CuO nano-fertilizers on human dietary safety was evaluated, the HQ > 1 in the 500 mg/L CuO NPs treatment indicated a potential health risk to Chinese adults, which was reduced by the coatings. This work explored for the first time the mechanism of coating effects on nanoparticles migration efficiency and phytotoxicity at the molecular level and demonstrated that the migration of nanoparticles between tissues could have an impact on phytotoxicity. It implied that coating can be tailored to target nanoparticles to specific regions of the plant. In addition, this study highlights the potential health risks associated with the consumption of I. aquatica fertilized with CuO NPs and provides valuable insights into the environmental applications of nano-fertilizers.

Antimony (Sb) and arsenic (As) are chemical analogs, but their behaviors in plants are different. To investigate the Sb uptake, translocation and speciation in As-hyperaccumulator P. cretica, a hydroponic experiment was conducted. In this study, P. cretica was exposed to 0.2-strength Hoagland nutrient solution, which contained 0.5 or 5 mg/L antimonite (SbIII) or antimonate (SbV). After 14 d exposure, P. cretica took up 1.4–2.8 times more SbIII than SbV. Since P. cretica was unable to translocate Sb, its roots accumulated >97% Sb with the highest at 7965 mg/kg. In both SbIII and SbV treatments, SbIII was the predominant species in P. cretica, with 90–100% and 46–100% SbIII in the roots. As the first barrier against Sb to enter plant cells, more Sb was accumulated in cell wall than cytosol or organelles. The results suggest that P. cretica may detoxify Sb by reducing SbV to SbIII and immobilizing it in root cell walls. Besides, the presence of SbIII significantly reduced the concentrations of dissolved organic C including organic acids in P. cretica root exudates. Further, increasing Sb levels promoted P accumulation in the plant, especially in the fronds, which may help P. cretica growth. The information from this study shed light on metabolic transformation of Sb in As-hyperaccumulators P. cretica, which helps to better understand Sb uptake and detoxification by plants.

Since the urbanization and industrialization are wildly spread in recent decades, the concentration of Zn in soil has increased in various regions. Although the interactions between P and Zn has long been recognized, the effect of high level of Zn on P uptake, translocation and distribution in rice and its molecular mechanism are not fully understood. In this study, we conducted both hydroponic culture and field trial with different combined applications of P and Zn to analyze the rice growth and yield, the uptake, translocation and distribution of P and Zn, as well as the P- and Zn-related gene expression levels. Our results showed that high level of Zn decreased the rice biomass and yield production, and inhibited the root-to-shoot translocation and distribution of P into new leaves by down-regulating P transporter genes OsPT2 and OsPT8 in shoot, which was controlled by OsPHR2-OsmiR399-OsPHO2 module. High Zn supply triggered P starvation signal in root, thereafter increased the activities of both root-endogenous and -secreted acid phosphatase to release more Pi, and induced the expression OsPT2 and OsPT8 to uptake more P for plant growth. On the other hand, high level of P significantly decreased the Zn concentrations in both root and shoot, and the root uptake ability of Zn through altering the expression levels of OsZIPs, which were further confirmed by the P high-accumulated mutant osnla1-2 and OsPHR2-OE transgenic plant. Taken together, we revealed the physiological and molecular mechanisms of P–Zn interactions, and proposed a working model of the cross-talk between P and Zn in rice plants. Our results also indicated that appropriate application of P fertilizer is an effective strategy to reduce rice uptake of excessive Zn when grown in Zn-contaminated soil.

Production of chrysanthemum (Dendranthema grandiflora) in greenhouses often requires intensive pesticide use, which raises serious concerns over food safety and human health. This study investigated uptake, translocation and residue dissipation of typical fungicides (metalaxyl-M and fludioxonil) and insecticides (cyantraniliprole and thiamethoxam) in greenhouse chrysanthemum when applied in soils. Chrysanthemum plants could absorb these pesticides from soils via roots to various degrees, and bioconcentration factors (BCFLS) were positively correlated with lipophilicity (log Kₒw) of pesticides. Highly lipophilic fludioxonil (log Kₒw = 4.12) had the greatest BCFLS (2.96 ± 0.41 g g⁻¹), whereas hydrophilic thiamethoxam (log Kₒw = −0.13) had the lowest (0.09 ± 0.03 g g⁻¹). Translocation factors (TF) from roots to shoots followed the order of TFₗₑₐf > TFₛₜₑₘ > TFfₗₒwₑᵣ. Metalaxyl-M and cyantraniliprole with medium lipophilicity (log Kₒw of 1.71 and 2.02, respectively) and hydrophilic thiamethoxam showed relatively strong translocation potentials with TF values in the range of 0.29–0.81, 0.36–2.74 and 0.30–1.03, respectively. Dissipation kinetics in chrysanthemum flowers followed the first-order with a half-life of 21.7, 5.5, 10.0 or 8.2 days for metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam, respectively. Final residues of these four pesticides, including clothianidin (a primary toxic metabolite of thiamethoxam), in all chrysanthemum flower samples were below the maximum residue limit (MRL) values 21 days after two soil applications each at the recommended dose (i.e., 3.2, 2.1, 4.3 and 4.3 kg ha⁻¹, respectively). However, when doubling the recommended dose, the metabolite clothianidin remained at concentrations greater than the MRL, despite that thiamethoxam concentration was lower than the MRL value. This study provided valuable insights on the uptake and residues of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam (including its metabolite clothianidin) in greenhouse chrysanthemum production, and could help better assess food safety risks of chrysanthemum contamination by parent pesticides and their metabolites.

High sensitivity towards Cu toxicity is problematic when using some hyperaccumulator plants for phytoremediation of soils with mixed contamination of Cu. Sedum alfredii, a Cd/Zn co-hyperaccumulator and Pb accumulator, is widely used for remediation of Cd, Zn, and Pb co-contaminated soils in China. In this paper, the tolerance and accumulation ability of S. alfredii towards Cu stress and its potential for phytoremediation of multi-metal polluted soils have been studied. Both the hyperaccumulating ecotype (HE) and non-hyperaccumulating ecotype (NHE) of S. alfredii accumulated high Cu in the roots and translocated minimal Cu to the shoots, and Cu in the stems and leaves mostly restricted in the vascular tissues (phloem zone). The HE plants, however, exhibited high Cu resistance with stimulated lateral root growth and increased chlorophyll content under 10 μM Cu treatment. XANES analysis showed that Cu in HE roots comprised Cu²⁺ (46.7%), Cu-histidine (35.2%) and Cu-cell wall (18.1%). The NHE under Cu stress showed decreased biomass, reduced leaf chlorophyll content, altered root architecture, and higher Cu localized to root cell wall as compared with the HEs. Potted HE plants thrived six months in multi-metal contaminated soils including 3897 mg kg⁻¹ available Cu. In conclusion, HE S alfredii is highly tolerant toward Cu due to metal homeostasis in root cells. Therefore, this plant has great potential to remediate Zn, Cd, and Pb contaminated soils those also contain high levels of Cu.

Benzene kresoxim-methyl (BKM) is an important methoxyacrylate-based strobilurin fungicide widely used against various phytopathogenic fungi in crops. Uptake, translocation and accumulation of BKM in vegetables remain unknown. This study was designed to investigate uptake, translocation, and accumulation of ¹⁴C-BKM and/or its potential metabolites in Chinese flowering cabbage and water spinach. ¹⁴C-BKM can be gradually taken up to reach a maximum of 44.4% of the applied amount by Chinese flowering cabbage and 34.6% by water spinach at 32 d after application. The ¹⁴CO₂ fractions released from the hydroponic plant system reached 37.8% for cabbage and 45.8% for water spinach, respectively. Concentrations of ¹⁴C in leaves, stems and roots all gradually increased as vegetables growing, with relative 44.9% (cabbage) and 26.8% (water spinach) of translocated from roots to edible leaves. In addition, ¹⁴C in leaves was mainly accumulated in the bottom leaves, which was visualized by quantitative radioautographic imaging. The bioconcentration factor of ¹⁴C ranged from 7.1 to 38.2 mL g⁻¹ for the cabbage and from 8.6 to 24.6 mL g⁻¹ for the water spinach. The translocation factor of BKM ranged from 0.10 to 2.04 for the cabbage and 0.10–0.46 for the water spinach throughout the whole cultivation period, indicating that the cabbage is easier to translocate BKM from roots to leaves and stems than water spinach. In addition, the daily human exposure values of BKM in both vegetables were much lower than the limited dose of 0.15 mg day⁻¹. The results help assess potential accumulation of BMK in vegetables and potential risk.

Frequently detected residuals of antibiotics in crops has drawn increasing attention from research community and the general public. This study was conducted under the controlled environmental conditions to investigate the uptake, translocation and distribution of three different veterinary antibiotics (VAs) in plants of Zea mays L. (maize, the third largest crop in the world, especially in China) and the associated mechanisms. The distribution color-maps of mixed-VAs showed that the highest RCF (root concentration factors) values of chlortetracycline (CTC) and sulfamethoxazole (SMZ) were found in the 0.5–2.0 mm zone (cell division zone), while the highest RCF value of sulfathiazole (ST) was in the 6.0–8.0 mm zone (elongation zone) of root tips (0.5–10.0 mm) after 120 h of exposure to VAs. The translocation factor (TF) of CTC was greater than 1.0, but the TFs of SMZ and ST were less than 1.0 under addition of single antibiotic. However, the TFs of three VAs were all greater than 1.0 at the end of exposure under addition of mixed-VAs. The dissipation of antibiotics by maize was also demonstrated by harvesting all plant parts in an enclosed system. The possible mechanisms for uptake and translocation of VAs in maize were investigated by adding multiple respiration inhibitors into the culture solution. The RCFs of VAs were suppressed heavily by salicylhydroxamic acid (SHAM) and sodium azide (NaN3), which indicates that the uptake of VAs was an active process. The results of TFs and stem concentration factors (SCFs) of CTC and SMZ in HgCl2 treatments revealed that the translocation of VAs was associated with the aquaporin activity in maize. The findings from this study will have significant implications for the management of crop food contamination by VAs and for the development of phytoremediation technology for antibiotics in the environment.

Carbamazepine (CBZ) is an antiepileptic drug that is frequently detected in wastewater treatment plants, soil and plants after irrigation with treated wastewater or application of biosolids. However, little information is available on the fate and uptake of CBZ in edible vegetables. In this study, radioautographic visualization of the ¹⁴C distribution revealed that ¹⁴C-CBZ can be taken up by all three ready-to-eat vegetables. Furthermore, a mass-balance study was conducted to evaluate the dynamic processes of the uptake and translocation of CBZ by ¹⁴C labeling. ¹⁴C-CBZ was gradually taken up with the growth of vegetables, with maximum uptake ratios of 2.19 ± 0.15, 2.86 ± 0.24 and 0.25 ± 0.05% of applied ¹⁴C in celery, carrot and pak choi, respectively. The bioconcentration factors (BCFs) based on ¹⁴C measurements ranged from 7.6 to 26.1 for celery, 3.6–12.9 for carrot, and 4.4–44 for pak choi. ¹⁴C-CBZ was easily translocated from the roots to the leaves and/or stems. The amendment of biosolids had a significant inhibitory effect on the uptake and translocation of ¹⁴C-CBZ from soil.

Irrigation with treated wastewater (TWW) and application of biosolids to arable land expose the agro-environment to pharmaceuticals and personal care products (PPCPs) which can be taken up by crops. In this project, we studied the effect of a carrier medium (e.g., biosolids and TWW) on plant (tomato, wheat and lettuce) uptake, translocation and metabolism of carbamazepine as a model for non-ionic PPCPs. Plant uptake and bioconcentration factors were significantly lower in soils amended with biosolids compared to soils irrigated with TWW. In soils amended with biosolids and irrigated with TWW, the bioavailability of carbamazepine for plant uptake was moderately decreased as compared to plants grown in soils irrigated with TWW alone. While TWW acts as a continuous source of PPCPs, biosolids act both as a source and a sink for these compounds. Moreover, it appears that decomposition of the biosolids in the soil after amendment enhances their adsorptive properties, which in turn reduces the bioavailability of PPCPs in the soil environment. In-plant metabolism of carbamazepine was found to be independent of environmental factors, such as soil type, carrier medium, and absolute amount implemented to the soil, but was controlled by the total amount taken up by the plant.