Combined Effects Of Microplastics Research Articles

Toxicological Effects of Microplastics and Sulfadiazine on the Microalgae Chlamydomonas reinhardtii.

Despite the fact that microplastics (MPs) facilitate the adsorption of environmental organic pollutants and influence their toxicity for organisms, more study is needed on the combination of MPs and antibiotics pollutant effects. In this study, polystyrene MPs (1 and 5 μm) and sulfadiazine (SDZ) were examined separately and in combination on freshwater microalga, Chlamydomonas reinhardtii. The results suggest that both the MPs and SDZ alone and in combination inhibited the growth of microalgae with an increasing concentration of MPs and SDZ (5–200 mg l–1); however, the inhibition rate was reduced by combination. Upon exposure for 7 days, both the MPs and SDZ inhibited algal growth, reduced chlorophyll content, and enhanced superoxide dismutase (SOD) activities, whereas glutathione peroxidase (GSH-Px) activity was elevated only with the exposure of 1 μm MPs. Fluorescence microscopy and scanning electron microscopy also indicated that particle size contributed to the combined toxicity by aggregating MPs with periphery pollutants. Further, the amount of extracellular secretory protein increased in the presence of MPs and SDZ removal ratio decreased when MPs and SDZ coexisted, suggesting that MPs affected SDZ metabolism by microalgae. The particle size of microplastics affected the toxicity of MPs on microalgae and the combined effect of MPs and SDZ could be mitigated by MPs adsorption. These findings provide insight into microalgae responses to the combination of MPs and antibiotics in water ecosystems.

Variations in the life-cycle parameters and population growth of rotifer Brachionus plicatilis under the stress of microplastics and 17β-estradiol

The toxic effects of microplastics (MPs) on biota are related to their particle size. In addition, MPs could adsorb ambient pollutants in water, which increase the threat of MPs to organisms. In this study, the effects of different particle sizes and concentrations of MPs on the life-cycle parameters and population growth of rotifer Brachionus plicatilis were investigated, and the combined effects of MPs and 17β-estradiol (E2) on rotifers were studied. Results showed small particle size (50 nm) MPs had negative effects on the lifespan, time to first batch of eggs, fecundity, and population growth rate of rotifers, which were dose-dependent, but large (100 nm and 500 nm) MPs were not. In addition, both life-cycle parameters and the population growth of rotifers were not affected by E2. However, the combination effects of different particle sizes of MPs and E2 on the lifespan, reproductive period, offspring per female, and population growth of rotifers were significant. Therefore, rotifers were more vulnerable to smaller particle MPs, and the coexistence of MPs and other environmental pollutants posed a serious threat to rotifers.

Combined effect of diazepam and polystyrene microplastics on the social behavior of medaka (Oryzias latipes)

The combined effect of microplastics and pharmaceuticals on aquatic organisms is an issue of concern. In this laboratory study, we evaluated the combined effect of polystyrene microplastics (2-μm diameter) and diazepam on the social behavior of medaka (Oryzias latipes) by using the shoaling behavior test with five treatment groups: solvent control, polystyrene microplastics exposure (0.04 mg/L), low-concentration diazepam exposure (0.03 mg/L), high-concentration diazepam exposure (0.3 mg/L), and polystyrene microplastics and low-concentration diazepam co-exposure. After 7 days of exposure, the shoal-leaving behavior of the high-concentration diazepam exposure group (8.9 ± 8.3 counts/medaka) and the co-exposure group (6.8 ± 6.7 counts/medaka) was significantly greater than that in the solvent control group (1.8 ± 2.6 counts/medaka). Even after 5 days of recovery, medaka in the co-exposure group left the shoal more often (7.3 ± 5.0 counts/medaka) than those in the solvent control group (2.6 ± 2.6 counts/medaka), whereas the shoal-leaving behavior in other exposure groups, except for the high-concentration diazepam exposure group, was restored. Our findings show that the combined effects of diazepam and polystyrene microplastics suppressed medaka social behavior, suggesting that the presence of microplastics can enhance the adverse effects of pollutants on the social behavior of aquatic organisms.

Microplastics as an Emerging Environmental Pollutant in Agricultural Soils: Effects on Ecosystems and Human Health

Microplastics are <5 mm in size, made up of diverse chemical components, and come from multiple sources. Due to extensive use and unreasonable disposal of plastics, microplastics have become a global environmental issue and have aroused widespread concern about their potential ecological risks. This review introduces the sources, distribution and migration of microplastics in agricultural soil ecosystems. The effects of microplastics on soil physicochemical properties and nutrient cycling are also discussed. Microplastics can alter a series of key soil biogeochemical processes by changing their characteristics, resulting in multiple effects on the activities and functions of soil microorganisms. The effects of microplastics on soil animals and plants, the combined effects of microplastics and coexisting pollutants (organic pollutants and heavy metals), and their potential risks to human health are also discussed. Finally, prevention and control strategies of microplastic pollution in agricultural soil ecosystems are put forward, and knowledge gaps and future research suggestions about microplastic pollution are given. This review improves the understanding of environmental behavior of microplastics in agricultural soil ecosystems, and provides a theoretical reference for a better assessment of the ecological and environmental risks of microplastics.

Co-exposure of polystyrene microplastics and iron aggravates cognitive decline in aging mice via ferroptosis induction

The objective of this study was to investigate the effects of co-exposure of iron and microplastics (MPs) on the cognitive function of aged humans and animals. It was already known that individual iron or MPs exposure can initiate potential neurotoxicity. However, the combined effect of MPs and iron remained to be elucidated. In this study, the toxicity of iron, MPs, co-treatment of MPs & iron, and the underlying mechanisms were evaluated in vivo. Our findings suggest that 5 µm MPs could enter the aging mice brain and accumulate in cortex and hippocampus. In addition, MPs and iron have a good binding ability, therefore, co-exposure of MPs & iron cause significant iron overload and cognitive deficits as compared to control and individual treatments of iron and MPs. Moreover, the lipid peroxidation and inflammation, which are involved in ferroptosis, get significantly elevated by co-exposure of iron and MPs. Taken together, our results provide compelling evidence that co-exposure of iron and MPs could aggravate the cognitive impairment via disturbing brain iron homeostasis and inducing ferroptosis in cognitive-related brain areas, what’s more, the results warn that MPs may act as vectors of pollutants (mostly heavy metals) increasing the health burden on body.

Combined Effects of Microplastics and Benzo[a]pyrene on the Marine Diatom Chaetoceros muelleri

Microplastics are regarded as ubiquitous pollutants in the ocean and have attracted worldwide concerns. Benzo[a]pyrene (B[a]P), one of typical polycyclic aromatic hydrocarbons (PAHs), is commonly detected in marine environment. Once coexisted, the microplastics and B[a]P may interact with each other and result in combined toxicity to organisms, and these remain to be systematically elucidated. Thus, this study aims to investigate (i) the effects of single micro-sized polystyrene (mPS), polyethylene terephthalate (mPET), and B[a]P on cell growth of Chaetoceros muelleri; and (ii) the interaction of microplastics and B[a]P, and their combined effects on C. muelleri. The results showed that both single microplastics and B[a]P at a high concentration of 150 μg/L inhibited the growth of C. muelleri. For single treatment of microplastics, stronger inhibition effects on microalgae was caused by mPET than that of mPS, with the highest IR of 25.23 and 11.17%, respectively. This may be attributed to the obvious surface roughness of mPET. By comparison, the combined effects of microplastics and B[a]P significantly inhibited the growth of C. muelleri as compared with the single treatment of B[a]P (P < 0.05). Synergistic effect was found in the combination of microplastics with B[a]P at high concentrations of 150 μg/L. Interestingly, the antagonistic effect on C. muelleri was observed in the combined treatment of microplastics and B[a]P at low concentrations of 10 μg/L. In addition, the pollutants reduced the content of photosynthetic pigments in microalgal cells. The SOD and MDA content of microalgae increased in the early stage of exposure to pollutants (e.g., Days 1 and 5), but decreased in the later stage (Day 15) compared with the control group. The decreased superoxide dismutase (SOD) and catalase (CAT) activity in single and composite systems may indicate that the antioxidative enzymatic system of microalgae has been inhibited or destroyed. This study will be helpful to further explore the ecological threats of microplastics and PAHs to the marine ecosystem.

Micro plastics in soil ecosystem - A review of sources, fate, and ecological impact

In recent years, environmental experts and stakeholders have paid increased attention to the pollution of micro plastics in the soil. As persistent pollutants, micro plastics have a significant impact on the soil ecology, agricultural production, and the overall health of the ecological environment. Micro plastics can influence soil bio-physicochemical properties and the mobility of other contaminants in soil, with potentially significant implications on soil ecosystem functionality. Thus, functions including litter decomposition, soil aggregation or those related to nutrient cycling can be altered. Furthermore, micro plastics can influence soil biota at different trophic levels, and even threaten human health through food chains. Despite this potential negative interaction, there is limited research on micro plastics in the soil environment. The primary goals of this review are to summarise the sources, distribution characteristics, migration and degradation laws of micro plastics in the soil ecosystem, to summarise the combined effects of micro plastics and other pollutants in the soil ecosystem, to analyse the effects of micro plastics on soil physical and chemical properties, animals, plants, and microorganisms, and to reveal the effects of micro plastics on soil ecosystem and to according to the distribution characteristics of soil micro plastics, degradation, migration and ecological effects, propose pollution control measures. This current review will provide a comprehensive understanding of soil pollution by micro plastic and offer a scientific basis for the formulation of novel management practices that will protect and improve soils, and contribute to the sustainable development of the ecological environment and highlight important areas for future research.

Individual and Combined Effects of Microplastics and Oxytetracycline on Cherry Radish

Individual and Combined Effects of Microplastics and Oxytetracycline on Cherry Radish

Antagonistic effects of copper and microplastics in single and binary mixtures on development and reproduction in the freshwater cladoceran Daphnia carinata

The combined effect of microplastics (MPs) and other contaminants such as trace metals is largely unknown although MPs can act as a vector for other contaminants. The present study investigated the impact of a single and mixture of MPs and a common trace contaminant, copper (Cu) on the Australian freshwater cladoceran Daphnia carina . No acute value was recorded when D. carinata was exposed to clear polyethylene size of 1–10 μ m with the concentration ranging from 5, 25, 50, 100, 200 and 300 mg/L during 48 h of exposure. D. carinata showed a tendency to utilize MPs from the surrounding environment to prolong their life when the food was scarce. When D. carinata were exposed to environmentally relevant concentrations of Cu: 1 and 3 μ g/L or MPs concentration of 0.25 and 1 mg/L for 21 days, no effects on reproduction was recorded. The impacts of Cu and MPs on molting frequency in the mixture treatments were less than in the single contaminant treatments. D. carinata juveniles were more sensitive to Cu than the adults regardless of the presence or absence of MPs. The findings highlight the importance of clarifying the interaction between traditional and contaminants of emerging concern for effective risk assessment. • Microplastics (MPs) could prolong the survival of D. carinata when food was scarce. • Reproduction in D. carinata was not affected by exposure to MPs and Cu individually. • D. carinata juveniles were more sensitive to Cu than adults. • Effects of Cu on moulting of D. carinata was smaller in the presence of MPs.

Combined effects of copper and microplastics on physiological parameters of Tubastrea aurea corals.

Microplastics (MPs) have been a serious environmental problem because it can carry pollution like heavy metals and organic pollutants. However, the combined effect of MPs and bivalent copper ion (Cu(II)) on the coral azooxanthellate has been rarely studied. In the present study, the combined effects of PVC and Cu(II) on the physiological responses of Tubastrea aurea were studied. Our results showed that MPs alone enhanced the activity of catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH). The mixture groups had the same effects on the CAT and GSH, which enhanced CAT and GSH activity by 97% and 53% respectively. MPs alone and the combined treatment groups decreased the activity of lipid peroxide (LPO) and the content of metallothionein (MT) by 45% and 20% of the coral Tubastrea aurea. Cu(II) exposure always had negative effect on the physiological parameters of coral, and MPs decreased the toxicity of Cu(II) in the combined groups. This work is the first time to report the combined effects of Cu(II) and microplastics on azooxanthellate coral, which will provide important preliminary data for the following research.

Single and Combined Effects of Microplastics and Cadmium on the Cadmium Accumulation and Biochemical and Immunity of Channa argus.

Microplastics can accumulate residual drugs and heavy metals in the environment and accumulate through the layers of the food chain, ultimately causing harm to human health. The pollution of microplastics in the freshwater environment is becoming more and more serious, which directly affects the safety of aquatic organisms. This experiment studied the effects of single and composite microplastics and Cd on the tissue damage, antioxidant, and immune response of juvenile Channa argus. Microplastics with different diameters of 80nm, 0.5μm (200μg/L), and Cd (50μg/L) were used for exposure, and four sampling points were set for 24h, 48h, 96h, and clear 48h. Under different treatments, a certain degree of gill tissue damage can be found in 96h. Microplastics and Cd can cause oxidative stress and affect the antioxidant status, and the impact of 0.5-μm microplastics is stronger than that of 80-nm microplastics. There is an antagonistic effect between the two microplastics and Cd during compound exposure, but the activity of CAT shows a synergistic effect. Microplastics and Cd affect the expression of immune-related genes to varying degrees. When exposed together, the expression of HSP70 gene all showed mutual antagonism, while the expression of IL-1β gene was different. The expression of the MT gene can infer the ability of microplastics to accumulate Cd, and microplastics with a small diameter of 80nm have stronger enrichment capabilities.

Interactions between microplastics and microorganisms in the environment: Modes of action and influencing factors

The widespread presence of microplastics (MPs) in the environment has led to the rise of the study on the interaction between MPs and microorganisms. The variety and characteristics of MPs in the environment make their interaction with microorganisms more complex. Recent studies have found that MPs can also serve as an important carrier for microorganisms to form fully developed biofilms on the substrates. The emergence of new ecological sites will also affect the ecosystem of water and soil. We present the latest knowledge of MPs' interactions with microorganisms and summarize their respective potential impacts on the environment. It was found that the main factors affecting microbial colonization on MPs were the characteristics of MPs, exposure time and environmental factors. Furthermore, microbial colonization on MPs can affect the composition and distribution of the microbial community in the environment, as well as the migration and transformation of other contaminants which also occur in the animal guts. When it come to the toxicity of MPs to microorganisms, it has been found that the main effects of MPs on microorganisms are the effect on microbial growth, photosynthesis of microorganisms and some single cells. In addition, the combined effects of MPs with heavy metals and organic compounds on microorganisms can be divided into antagonistic effects, synergistic toxicity, promoting effects and non-effects. In turn, microbes will have impacts on MPs in terms of degradation, absorption, transfer and deposition. In practical application, MPs will affect the biological treatment stage of sewage treatment. This review discusses the interaction mechanism and influencing factors between microorganisms and MPs. It also called for active exploration of methods for treating MPs with microorganisms in the actual environment, providing a theoretical basis for the treatment of microorganisms, and a better understanding of the environmental behavior and ecological risk assessment of MPs.

Single and combined effects of microplastics, pyrethroid and food resources on the life-history traits and microbiome of Chironomus riparius

There is growing evidence of widespread contamination of freshwater ecosystems with microplastics. However, the effects of chronic microplastic ingestion and its interaction with other pollutants and stress factors on the life-history traits and the host-microbiome of aquatic invertebrates are not well understood. This study investigates the effects of exposure to sediment spiked with 1 μm polystyrene-based latex microplastic spheres, an environmentally realistic concentration of a pyrethroid pesticide (esfenvalerate), and a combination of both treatments on the life-history traits of the benthic-dwelling invertebrate, Chironomus riparius and its microbial community. The chironomid larvae were also exposed to two food conditions: abundant or limited food in the sediment, monitored for 28 and 34 days respectively. The microplastics and esfenvalerate had negative effects on adult emergence and survival, and these effects differed between the food level treatments. The microbiome diversity was negatively affected by the exposure to microplastics, while the relative abundances of the four top phyla were significantly affected only in the high food level treatment. Although the combined exposure to microplastics and esfenvalerate showed some negative effects on survival and emergence, there was little evidence for synergistic effects when compared to the single exposure. The food level affected all life-history traits and the microbiota, and lower food levels intensified the negative effects of the exposure to microplastics, esfenvalerate and their combination. We argue that these pollutants can affect crucial life-history traits such as successful metamorphosis and the host-microbiome. Therefore, it should be taken into consideration for toxicological assessment of pollutant acceptability. Our study highlights the importance of investigating possible additive and synergic activities between stressors to understand the effects of pollutants in the life story traits and host-microbiome.

Microplastics on the growth of plants and seed germination in aquatic and terrestrial ecosystems

Growth of plants, apart from being complex and highly dynamic, is directly dependent on the environmental conditions, particularly the quality of soil for terrestrial plants and the water quality for aquatic plants. Presence of microplastics in the environment may affect the plant growth in numerous ways depending on the contents of the growing medium. However, increasing presence of microplastics at an alarming rate due to its pervasive usage and mismanagement of plastics have led to significant environmental problems. Several research studies have been conducted as well as reviewed to investigate the toxic effects of microplastics on aquatic systems, but studies that investigate the toxic effect of microplastics on the terrestrial systems are limited. Hence, in this review the individual and the combined effects of microplastics on the growth of plants and seed germination in both aquatic and terrestrial ecosystems are concisely discussed. At the beginning accumulation of microplastics on aquatic and terrestrial ecosystem is discussed and the reasonable solutions are highlighted that can mitigate the effects from the widespread increase of the plastic debris. Thereafter, the individual and combined effect of microplastics on seed germination and plant growth is reviewed separately while summarizing the important aspects and future perspectives. This review will provide an insight into the existing gap in the current research works and thus could offer possible implications on the effect of microplastics on plant growth and seed germination in aquatic and terrestrial ecosystem.

Combined hepatotoxicity of imidacloprid and microplastics in adult zebrafish: Endpoints at gene transcription

Microplastics (MPs) and pesticides are two kinds of ubiquitous pollutants that can pose a health risk to aquatic organisms. However, researches about the combined effects of MPs and pesticides are very limited. A simple combined exposure model was established in this study, adult zebrafish were exposed to 100 μg/L imidacloprid (IMI), 20 μg/L polystyrene microplastics (PS), and a combination of PS and IMI (PS + IMI) for 21 days. The results demonstrated that exposure to PS and IMI inhibited the growth of zebrafish and altered the levels of glycolipid metabolism and oxidative stress-related biochemical parameters. While gene expression analysis revealed that, compared with PS or IMI treatment group, combined exposure caused a greater change in gene expression levels involving the process of glycolipid metabolism (Gk, Hk1, Aco, PPar-α, Cpt1, Acc, Fas, PPar-γ, Apo) and inflammatory response (IL-1β, IL-6, IL-8, TNF-α, IL-10). The results demonstrated that even combined exposure of low concentrations of PS and IMI could cause more severe hepatotoxicity in zebrafish, especially in terms of gene transcription. And more combined toxicity studies are essential for MPs and pesticides risk assessment.

Long-term adverse effects of microplastics on Daphnia magna reproduction and population growth rate at increased water temperature and light intensity: Combined effects of stressors and interactions

In many ecosystems, the zooplankton community has been pressured simultaneously by microplastic pollution and alterations resulting from global climate changes. The potential influence of light intensity rise (from 10,830 lx to 26,000 lx) and water temperature rise (from 20 °C to 25 °C) on the long term-toxicity of microplastics (MPs) to Daphnia magna were investigated. Three 21-day laboratory bioassays with model MPs (1–5 μm diameter) were carried out at (i) 20 °C/10830 lx, (ii) 20 °C/26000 lx, and (iii) 25 °C/10830 lx. In each bioassay, one control (no MPs) and three MP concentrations (0.04, 0.09, 0.19 mg/L) were tested. In all the bioassays, MPs caused parental and juvenile mortality, and reduced the somatic growth, reproduction and population growth rate. The MP EC50s on living offspring (95% confidence interval within brackets) were 0.146 mg/L (0.142–0.151 mg/L) at 20 °C/10830 lx, 0.102 mg/L (0.099–0.105 mg/L) at 20 °C/26000 lx, and 0.101 mg/L (0.098–0.104 mg/L) at 25 °C/10830 lx. Relatively to the respective control group, 0.19 mg/L of MPs decreased the mean of the population growth rate by 27% at 20 °C/10830 lx, 38% at 20 °C/26000 lx and 59% at 25 °C/10830 lx. Based on the population growth rate and in relation to 20 °C/10830 lx (control, no MPs), the interaction between increased light intensity (26,000 lx) and MPs was synergism (at all the MP concentrations tested). The interaction between water temperature rise (25 °C) and MPs was antagonism at 0.04 mg/L of MPs and synergism at 0.09 and 0.19 mg/L of MPs. In the present scenario of climate changes and global MP pollution such findings raise high concern because zooplankton communities are crucial for aquatic biodiversity conservation, ecosystem functioning and services provided to humans. Further studies on the combined effects of MPs, other common pollutants, and alterations due to climate changes are needed.

Combined effect of microplastics and global warming factors on early growth and development of the sea urchin (Paracentrotus lividus)

The aim of this work was to estimate the potential risk of the combined effect of global change factors (acidification, temperature increase) and microplastic (MP) pollution on the growth and development of the sea urchin P. lividus. Embryo-larval bioassays were conducted to determine growth and morphology after 48 h of incubation with MP (1000 and 3000 particles/mL); with filtered sea water at pH = 7.6; and with their combinations. A second experiment was conducted to study the effect of pH and MP in combination with a temperature increase of 4 °C compared to control (20 °C). We found that the inhibition of growth in embryos reared at pH = 7.6 was around 75%. Larvae incubated at 3000 MP particles/mL showed a 20% decrease in growth compared to controls. The exposure to MP also induced an increase in the postoral arm separation or rounded vertices. The combined exposure to a pH 7.6 and MP caused a significant decrease of larval growth compared to control, to MP and to pH 7.6 treatments. Morphological alterations were observed in these treatments, including the development of only two arms. Increasing the temperature resulted in an increased growth in control, in pH 7.6 and pH 7.6 + MP3000 treatments, but the relative stomach volume decreased. However, when growth parameters were expressed per Degree-Days the lower growth provoked by the thermal stress was evidenced in all treatments. In this work we demonstrated that MP could aggravate the effect of a decreased pH and that an increase in water temperature generated an additional stress on P. lividus larvae, manifested in a lower growth and an altered development. Therefore, the combined stress caused by ocean warming, ocean acidification, and microplastic pollution, could threaten sea urchin populations leading to a potential impact on coastal ecosystems.

Microplastics in soils: an environmental geotechnics perspective

Microplastics (MPs) are emerging persistent contaminants in the terrestrial subsurface, and evidence has emerged for significant effects of MPs on the biological and ecosystem functions of soils. Main MP sources include land spreading of sewage sludge and biowaste composts, plastic mulching film used in horticultural fields, waste water irrigation and leachate from the landfills, among others. This updated state-of-the-art review paper describes recent experimental and numerical research and developments in understanding the accumulation and fate and effects of MPs in the soil environment (focusing on their storage, degradation, transportation, leaching to groundwater etc.), followed by mitigation and bioremediation measures, including MP-eating soil bacteria and fungi and the best management practices for reducing MP pollution of soil. Other areas covered are the combined effects of MPs and various other environmental contaminants (heavy metals, organic pollutants and antibiotics) in soil ecosystems and the standardisation of methods for detection, quantification and characterisation of MPs in soils, which is critical for MP research. The paper concludes by identifying knowledge gaps and presents recommendations on prioritised research needs.

Sampling, pre-treatment, and identification methods of microplastics in sewage sludge and their effects in agricultural soils: a review.

Microplastics are widely detected in wastewater treatment plants. They can remove microplastics from wastewaters with a high yield, but it means that microplastics are transferred and accumulated to sewage sludge. Lately, increasing attention has been paid to microplastics in raw and treated wastewaters. However, studies about quantification and identification of microplastics in sewage sludge are very scarce and need to be further investigated. Since the sludge-based microplastics are newly studied and are a challenging matrix due to high organic content, there is limited knowledge of sampling, pre-treatment methods, identification techniques, and expression units. Besides, treated sewage sludge is mostly used for soil amendment to improve soil fertility and it gives economic advantages. This situation creates a pathway for microplastics entering the soil environment with unknown consequences. To the best of our knowledge, microplastics have a large specific surface area, small size, and hydrophobicity which makes it a good adsorbent for other pollutants. Therefore, the combined effect of microplastics with adsorbed pollutants such as heavy metals, antibiotics, and persistent organic pollutants could give serious harm to soil safety and soil organisms. Herein, new developments in the methods for sampling, pre-treatment, and identification techniques of microplastics in sewage sludge were reviewed. Then, the abundance of microplastics, major polymer types, and shapes in sewage sludge were examined. Finally, the effects and ecological risks of microplastic pollution as a result of agricultural usage of sewage sludge in the soil environment have been summarized. Also, the main points for future research were highlighted.

Combined effect of microplastics and DDT on microbial growth: A bacteriological and metabolomics investigation in Escherichia coli

Microplastics (MPs) can adsorb toxic chemicals in biological or environmental matrixes and thus influence their behavior and availability. In order to investigate how the combined pollution of MPs and toxic organic chemical influence microbial growth and metabolism, Escherichia coli (E. coli) was grown in a complex, well-defined media and treated with polystyrene microplastics (PS MPs) and dichloro-diphenyl-tricgloroethane (DDT) at human relevant concentration levels. In vivo metabolites captured by a novel solid phase microextraction (SPME) probe, were used to reflect the metabolic dysregulation of E. coli under different pollution stresses. Results showed that the toxic effect of DDT displayed a distinct dose-dependent phenomenon while the existence of PS decreased the growth and metabolic interference effect of DDT on E. coli. Adsorption results revealed a mechanism that PS weakened the adverse impact of DDT by decreasing its free concentration in the treated culture media. Tricarboxylic acid (TCA) cycle related enzymes activities and antioxidant defense related substances of E. coli also proved the mechanism. The current study is believed to broaden our understanding of the ecotoxicity of MPs with toxic organic chemicals on microorganism.