Microplastics (MPs) in farmland soil may affect the environmental fate and toxicity of heavy metals; however, how non-biodegradable and biodegradable MPs change the accumulation and phytotoxicity of ...Cr(VI) to the plants is still unknown. In this study, we explored the impacts of Cr(VI) concentrations (0, 20, 50, 100, 200, and 500 μmol/L), MP types (polyethylene (PE), polyamide (PA), and polylactic acid (PLA)), sizes (13, 48, and 500 µm), and concentrations (40, 200, and 1000 mg/L) on the Cr accumulation and toxicity to cucumber (Cucumis sativus L.) under hydroponic conditions for 14 days. The results show that the presence of PE-MPs promoted the Cr accumulation in root by 8–39.8%. However, PA-MPs inhibited the Cr accumulation in the whole plant under less than 100 μmol/L Cr(VI). Notably, 1000 mg/L PA-MPs significantly reduced Cr accumulation in root and stem by 44.70% and 48.20%, respectively. Moreover, PE-MPs and PLA-MPs reduced the chlorophyll content and slowed down the growth of seedlings, while PA-MPs were beneficial to the growth of cucumber under 50–500 μmol/L Cr(VI) treatments, increasing the biomass by 20.99–189.99%. Furthermore, PE-MPs enhanced the content of MDA, especially under 500 μmol/L Cr(VI) concentration by 27.39%; however, the addition of PA-MPs and PLA-MPs slightly enhanced the enzyme activities including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Significantly, 1000 mg/L PA-MPs promoted biomass and reduced MDA content compared the control due to their high Cr(VI) adsorption efficiency. Thus, MP type, especially PE-MPs, mainly determined the Cr accumulation and phytotoxicity, which was attributed to the various adsorption capacities of MPs to Cr(VI).
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•PE-MPs caused higher Cr accumulation and phytotoxicity than PA-MPs and PLA-MPs.•MP type had greater effect on plant growth than MP size and concentration.•PA-MPs and PLA-MPs slightly enhanced the activities of SOD, POD, and CAT.•The impact mechanism was related to the adsorption capacities of MPs to Cr(VI).
In recent years, microplastics (MPs) as emerging carriers for environmental pollutants have attracted increasing worldwide attention. However, the adsorption of heavy metals on MPs, especially for ...biodegradable MPs, has been still poorly understood in estuarine environments. In this study, we investigated the aging of biodegradable and conventional MPs in the Pearl River Estuary after long-term exposure and their impacts on the adsorption of heavy metals from seawater. The results showed that the changes in surface characteristics were more prominent on biodegradable MPs than on conventional MPs after aging. Both biodegradable and conventional MPs could adsorb heavy metals, and their adsorption capacities fluctuated greatly on different MPs and different exposure times. The adsorption capacities of Cu, Pb, and As on biodegradable MPs were higher than those on conventional MPs, whereas Mn, Cr, and Co had lower adsorption on biodegradable MPs after 9–12 months by inductively coupled plasma-mass spectrometry (ICP-MS). The aging characteristics (CI, O/C, and Xc) of MPs accounted for a contribution of 51.0% on heavy metal adsorption, while the environmental factors (temperature, salinity, pH, and heavy metal concentration) only contributed to 13.2%. Therefore, the present study can provide important evidence on the environmental behaviors and ecological risks of biodegradable and conventional MPs in estuarine systems.
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•Adsorption of heavy metals on biodegradable MPs was first reported in the Pearl River Estuary.•The changes in the physicochemical property of biodegradable MPs were distinct.•Biodegradable MPs tend to particularly adsorb Cu, Pb, and As.•The aging properties of MPs had a strong relationship with heavy metal adsorption.
The continuous increase in synthetic plastic production and poor management in plastic waste have led to a tremendous increase in the dumping into our aqueous environment. Consequently, microplastics ...commonly defined as sizes less than 5 mm are produced and stay in both seawater and freshwater environment. The presence of microplastics as a new type of emerging contaminant has become a great issue of concerns from public and government authorities. The sources of microplastics to freshwater systems are many with the largest portion from wastewater treatment plants. The abundance of microplastics varies with the location, from above 1 million pieces per cubic meter to less than 1 piece in 100 cubic meters.
Microplastics can cause several harmful physical effects on humans and living organisms through such mechanisms as entanglement and ingestion. The microplastics can act as carriers of various toxins such as additives from industrial production processes and persistent contaminants by the sorption in waters. Those toxins may cause great health problems to humans. A few studies on the fishes demonstrated that the microplastics and the associated toxins are bio-accumulated and cause such problems as intestinal damage and change in metabolic profiles.
In studies of microplastics, fresh water is first sampled by the nets with typical mesh size of 330 μm for collection of microplastics. After the volume reducing process, the samples will then go through the purification process including density separation by such inorganic salts as sodium chloride and digestion process by oxidizing agents or enzymes. The sequence of these two processes (namely purification and digestion) is dependent on the sample type. The purified samples can be studied by several analytical methods. The commonly used methods for the qualification studies are FTIR spectroscopy, Raman spectroscopy, pyrolysis-GC/MS, and liquid chromatography. A tagging method can be used in the quantification study. Our literature study finds that there is still no universal accepted quantification and qualification tools of microplastics in fresh waters. More work is anticipated so as to obtain accurate information on microplastics in freshwater, which can then be used for the better assessment of the environmental risk.
•Microplastics exhibit high abundance in freshwater systems.•The knowledge about health impacts of freshwater microplastics is limited.•A summary of current microplastics research methodology is included.•Combination of appropriate analytical approaches should be adopted to assess microplastics in freshwaters.
•PS MPs (10 particles/mL) decreased bioaccumulation of BaP (0.4 nM) in mussels.•PS MPs reduced the adverse effect of BaP on histopathology and oxidative stress.•Dysregulation of mRNA expression ...caused by BaP was alleviated by PS MPs.•No adverse effects of the extractable additive solutions of PS MPs were observed.
As two major ubiquitous pollutants, microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) coexist in the marine environment. However, the role of MPs in altering the toxicity of PAHs to marine organisms is poorly understood. We therefore investigated the accumulation and toxicity of benzoapyrene (BaP, 0.4 nM), in the marine mussel Mytilus galloprovincialis over a 4-day of exposure with or without the presence of 10 μm polystyrene microplastics (PS MPs) (10 particles/mL). The presence of PS MPs significantly decreased BaP accumulation in soft tissues of M. galloprovincialis by approximately 6.7%. Single exposure of PS MPs or BaP decreased the mean epithelial thickness (MET) of digestive tubules and enhanced reactive oxygen species (ROS) levels in haemolymph, while upon co-exposure the adverse impacts were alleviated. Real-time q-PCR results showed that most selected genes involved in stress response (FKBP, HSP90), immune (MyD88a, NF-κB) and detoxification (CYP4Y1) were induced for both single exposure and co-exposure. The co-presence of PS MPs down-regulated the mRNA expression of NF-κB in gills compared with of BaP alone. The uptake and toxicity reductions of BaP might result from the decrease of its bioavailable concentrations caused by the adsorption of BaP by PS MPs and the strong affinity of BaP to PS MPs. Adverse outcomes for the co-existence of marine emerging pollutants under long-term conditions remain to be further validated.
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•Electrocoagulation technology had a significant removal (>91.7%) for microplastics.•Removal of fiber microplastics by EC was better than that of granular microplastics.•Removal rate ...of microplastics by Al anode EC was higher than that by Fe anode.•Mechanisms of microplastic removal by electrocoagulation technology were proposed.•This performance could be further utilized to improve microplastic removal in WWTPs.
With the gradual increase of microplastics in the water environment, it is imperative to understand the removal characteristics of microplastics in the current treatment process. Electrocoagulation (EC) is an effective water treatment technology. The purpose of this study is to investigate the removal performance, mechanism and influencing factors of microplastics in wastewater treatment by EC. The impacts of wastewater properties, including initial pH, electrolyte concentration, applied voltage density, anode materials, microplastic type and microplastic concentrations, on the removal efficiency of microplastics by EC were systematically investigated. The findings showed that aluminum anode was better than iron anode in the removal of microplastics, and the removal rate of was above 80% in all experiments, which indicates that aluminum anode EC is an effective method to remove microplastics in wastewater. The removal rate of four microplastics by EC can reach more than 82% in the range of pH 3–10, and the best removal rate was 93.2% for PE, 91.7% for PMMA, 98.2% for CA and 98.4% for PP at pH 7.2. The removal efficiency of fiber microplastics by EC is better than that of granular microplastics. The microplastic removal efficiency increased with the increase of electrolyte concentration and applied voltage density. Additionally, microplastics undergo flocculation and charge neutralization at the same time during EC. The economic evaluation of the reactor operation cost showed that the optimal EC reaction conditions were: 0.05 M of electrolyte concentration, pH 7.2, 10 V of applied voltage density and Al anode. Further research should focus on the possible reactor design and improvement to optimize the process and realize the replication and transfer from the laboratory to the sewage treatment plant.
Current understanding on the fate and behavior of microplastics (MPs) in complex soil media remains inadequate. We characterized the aging and hetero-aggregation of a MP sampled in farmland soil, and ...explored its vertical downward transport in natural loamy sand. The MP was identified with FTIR spectrum as polypropylene, a plastic lighter than water. FTIR spectrum combined with SEM imaging confirmed the MP was highly aged, generating colloidal plastic fibers and carbonyl groups. SEM imaging coupled with EDX analysis suggested hetero-aggregation of the MP with soil minerals. Soil leaching tests performed with the clean MP (without soil minerals) (CMP), the raw MP (RMP) (with soil minerals), and the RMP with humic acid (HA) (RMP + HA) demonstrated that the mobility was insignificant for the CMP, moderate for the RMP and highest for the RMP + HA, resulting in a maximal downward traveling distance of 0 cm, 3–4 cm, and 9–10 cm, respectively. Correlation between the maximal traveling distance and zeta potential of the CMP, RMP, and RMP + HA confirmed surface charge as a dominant control on the MP mobility; while the increasing density of the MP, due to hetero-aggregation with soil minerals, was identified as a driving mechanism for its downward transport, despite its intrinsic density lower than water. Occurrence of only the lower-sized rod-shaped plastic fibers at the maximal traveling distance suggested the natural aging, a process leading to plastic vibration and fragmentation, was conducive to plastic translocation. The three explored classes of antibiotic resistance genes (ARGs) (tetracycline, beta-lactam and sulfonamide) were all detected in the plastic surface, suggesting the MP may function as a potential pathway for the dissemination of ARGs to the deeper soil layer. These findings are important to understand the concentration distribution of both the MPs and ARGs in agriculture impacted soils, a natural reservoir of both emerging contaminants.
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•MPs even with a virgin density lower than water could transport downward in soil.•Both hetero-aggregation and aging promote the downward transport.•Hetero-aggregation with soil mineral and NOM increased MP density and zeta potential.•Aging reduced plastic particle size and produced rod-shaped plastic fibers.•MPs are potential vehicles for downward transport of ARGs in agricultural land.
Microplastics even lighter than water could transport downward in soil, due to hetero-aggregation and natural aging, and convey the ARGs to deep soil layers.
Emerging contaminants such as microplastics and engineered nanoparticles (NPs) have become an environmental issue of global concern, but little is known about their joint effects in soil–plant ...systems. We studied the effects of two microplastics, conventional non-degradable high–density polyethylene (HDPE) and biodegradable polylactic acid (PLA), on maize growth and arbuscular mycorrhizal (AM) fungal communities in a soil spiked with or without ZnO NPs. HDPE and low–dose PLA promoted plant growth, while high–dose PLA significantly decreased maize shoot (by 16%–40%) and root biomass (by 28%–50%), indicating high-dose PLA may have strong phytotoxicity. ZnO NPs displayed non-significant effects on plant growth, but caused greater Zn accumulation in plants. Both HDPE and PLA further increased Zn concentrations in roots, while decreasing Zn translocation to aerial parts. High–throughput sequencing showed that microplastics and ZnO NPs singly and jointly influenced AM fungal community composition and diversity, particularly the relative abundance of dominant genera. The presence of ZnO NPs and microplastics generally increased soil pH. Overall, our findings imply increasing contamination by microplastics and NPs can have profound ecological impacts on plant fitness, plant quality, and soil microbial community composition and diversity, resulting in uncertain consequences for agroecosystems.
•Interactions of microplastics and nanoparticles on mycorrhizae were first studied.•Polylactic acid had low-dose stimulation and high-dose inhibition effects on plants.•Polyethylene antagonistically interacted with ZnO nanoparticles on plant growth.•Microplastics altered Zn accumulation and translocation in plants exposed to ZnO.•Microplastics and ZnO nanoparticles altered AMF community structure and diversity.
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•Initial exploration of the effects of MPs and aged MPs on skin tissue and hair follicles.•Massive accumulation of ROS caused by MPs and aged MPs leads to skin oxidative stress.•Aged ...MPs exposure aggravated oxidative stress, apoptosis, and alopecia.•Aged MPs treatment promoted apoptosis via ROS-mediated mitochondrial pathway.
Microplastics (MPs) are pervasive pollutants in the natural environment and contribute to increased levels of illness in both animals and humans. However, thespecific impacts of MPs on skin damage and alopeciaare not yet well understood. In this study, we have examined the effects of two types of polystyrene MPs (pristine and aged) on skin and hair follicle damage in mice. UV irradiation changed the chemical and physical properties of the aged MPs, including functional groups, surface roughness, and contact angles. In both in vivo and in vitro experiments, skin and cell injuries related to oxidative stress, apoptosis, tight junctions (TJs), alopecia, mitochondrial dysfunction, and other damages were observed. Mechanistically, MPs and aged MPs can induce TJs damage via the oxidative stress pathway and inhibition of antioxidant-related proteins, and this can lead to alopecia. The regulation of cell apoptosis was also observed, and this is involved in the ROS-mediated mitochondrial signaling pathway. Importantly, aged MPs showed exacerbated toxicity, which may be due to their elevated surface irregularities and altered chemical compositions. Collectively, this study suggests a potential therapeutic approach for alopecia and hair follicle damage caused by MPs pollution.
Microplastics (MPs) have become an emerging threat for organisms. However, the toxicity mechanisms on biota, especially soil biota remain largely unclear. This study distinguished the effects of five ...types of MPs and their extractable additives on a typical soil oligochaete Enchytraeus crypticus using a traditional ecotoxicological approach combined with gut microbiota analysis. A variety of inorganic and organic compounds were screened in extractable solutions. Both MPs and their extractable additives decreased the growth and survival rates of the worms and shifted the gut microbiota, and the effects were type-specific. The differences between the effects of MPs and their extractable additives on traditional ecotoxicological parameters were insignificant, suggesting that extractable additives were the main toxicity pathways on soil fauna. The type-specific effects of MPs were attributed to the varied chemical compositions of extractable additives, and the compounds responsible for the shift of gut microbiota were further identified. The distinguishable effects on gut microbiota between MPs and their extractable additives together with the significant regressions between gut microbiota and traditional ecotoxicological parameters confirmed that gut microbiota could be a more sensitive indicator of organism's health conditions. Combined, the study provided an important insight into the toxicity mechanisms of MPs on soil fauna and extractable additives of MPs may be a hidden threat.
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•Both MPs and extractable additives aggravated health conditions and shifted gut microbiota.•MPs and extractable additives induced a type-specific effect on soil fauna.•The extractable additives of MPs highly contributed to the toxicity of MPs.•Key compounds responsible for MP toxicity were identified.•Gut microbiota could be a more sensitive parameter in ecotoxicology.
Microplastic (MP) pollution has become one of the global environmental concerns, but the contamination and effect of MP on chicken skeletal muscle are scarcely researched. Here, we found MP ...contamination in the chicken skeletal muscles, which were directly collected from a large-scale chicken farm. Using Pyrolysis-Gas Chromatography-Mass Spectrometry and Agilent 8700 laser direct infrared imaging spectrometer, we found that polystyrene (PS) and polyamide are the significant type of MPs detected in chicken skeletal muscle. Constant PS-MP oral feeding for >21 days increases the content of MP deposited in chicken breast muscle, but the MP content in the leg muscle was gradually decreased. Surprisingly, the chicken's body and skeletal muscle weight was increased after constant PS-MP feeding. Physiological results showed that PS-MP exposure inhibited energy and lipid metabolism, induced oxidative stress, and potential for neurotoxicity in the skeletal muscle. Metabolomic analysis of the liquid chromatography-tandem mass spectrometry and gas chromatography coupled with the mass spectrometer results showed that PS-MP exposure changed the metabolomic profile and reduced meat quality. In vitro, experimental results showed that PS-MP exposure induced chicken primary myoblasts proliferation and apoptosis but decreased myoblasts differentiation. Transcriptome analysis of the skeletal muscle indicates that PS-MP exposure affects skeletal muscle function by regulating genes involved in neural function and muscle development. Considering that chicken is one of the most important meat foods in the world, this study will provide an essential reference for protecting meat food safety.
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•Microplastics accumulate in the muscles of farmed broilers.•Polystyrene microplastics (PS-MPs) promote the muscle growth of broilers.•PS-MP exposure reduced meat quality but increased the muscle weight of chickens.•PS-MPs feeding can affect the expression of genes related to neural function.
