•Microplastic-induced changes affect soil function and soil microbial communities.•The effects of microplastics on soil or soil organisms depend on particle types, concentration and exposure ...time.•Consumption of microplastics can cause mechanical damage, chemical responses and disrupt gut microbial communities.•Microplastics have potential effects on plant growth and may accumulate and transport in plants.•Some bacteria biodegrade microplastics could be used for soil bioremediation.
Microplastics are emerging contaminants and their presence in water and soil ecosystems has recently drawn considerable attention because they pose a great threat to entire ecosystems. Recent researches have focused on the detection, occurrence, characterization, and toxicology of microplastics in marine and freshwater ecosystems; however, our understanding of the ecological effects of microplastics in soil ecosystems is still limited compared with that in aquatic ecosystems. Here, we have compiled literature, studying the sources, migration of microplastics in soil, negative impacts on soil health and function, trophic transfer in food chains, and the corresponding adverse effects on soil organisms in order to address the potential ecological and human health risks caused by microplastics in soil. This review aims to address gaps in knowledge, shed light on the ecological effects of microplastics in soil, and propose future studies on microplastic pollution and the resultant soil ecotoxicity. Furthermore, this review is focused on limiting microplastics in soil and establishing management and remediation measures to mitigate the risks posed by microplastic pollution.
Cadmium (Cd) accumulation in rice and its subsequent transfer to food chain is a major environmental issue worldwide. Understanding of Cd transport processes and its management aiming to reduce Cd ...uptake and accumulation in rice may help to improve rice growth and grain quality. Moreover, a thorough understanding of the factors influencing Cd accumulation will be helpful to derive efficient strategies to minimize Cd in rice. In this article, we reviewed Cd transport mechanisms in rice, the factors affecting Cd uptake (including physicochemical characters of soil and ecophysiological features of rice) and discussed efficient measures to immobilize Cd in soil and reduce Cd uptake by rice (including agronomic practices, bioremediation and molecular biology techniques). These findings will contribute to ensuring food safety, and reducing Cd risk on human beings.
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•Radial oxygen loss controls Fe plaque formation on rice roots and affects Cd uptake.•Flooding before and after heading is effective for reducing Cd uptake by rice.•Inoculation with suitable AMF can be applied to reduce Cd accumulation in rice.•Intercropping and rotation systems can decrease Cd uptake by rice.
Cd transport mechanisms, factors influencing Cd accumulation, and efficient strategies to reduce Cd uptake by rice are summarized.
Phthalates (PAEs) are extensively used as plasticizers and constitute one of the most frequently detected organic contaminants in the environment. With the deterioration of eco-environment in China ...during the past three decades, many studies on PAE occurrence in soils and their risk assessments have been conducted which allow us to carry out a fairly comprehensive assessment of soil PAE contamination on a nation-wide scale. This review combines the updated information available associated with PAE current levels, distribution patterns (including urban soil, rural or agricultural soil, seasonal and vertical variations), potential sources, and human health exposure. The levels of PAEs in soils of China are generally at the high end of the global range, and higher than the grade II limits of the Environmental Quality Standard for soil in China. The most abundant compounds, di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), display obvious spatial distribution in different provinces. It is noted that urbanization and industrialization, application of plastic film (especially plastic film mulching in agricultural soil) and fertilizer are the major sources of PAEs in soil. Uptake of PAEs by crops, and human exposure to PAEs via ingestion of soil and vegetables are reviewed, with scientific gaps highlighted.
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•PAE levels in soils of China were generally higher than the other countries.•DBP and DEHP are the dominant compounds in soil with obvious spatial distribution.•Urbanization and industrialization, application of plastic film and fertilizer are the major sources of PAEs in soil.•Uptake of PAEs by crops and human exposure to PAEs are reviewed.
Soil pollution with organic contaminants is one of the most intractable environmental problems today, posing serious threats to humans and the environment. Innovative strategies for remediating ...organic-contaminated soils are critically needed. Phytoremediation, based on the synergistic actions of plants and their associated microorganisms, has been recognized as a powerful in situ approach to soil remediation. Suitable combinations of plants and their associated endophytes can improve plant growth and enhance the biodegradation of organic contaminants in the rhizosphere and/or endosphere, dramatically expediting the removal of organic pollutants from soils. However, for phytoremediation to become a more widely accepted and predictable alternative, a thorough understanding of plant–endophyte interactions is needed. Many studies have recently been conducted on the mechanisms of endophyte-assisted phytoremediation of organic contaminants in soils. In this review, we highlight the superiority of organic pollutant-degrading endophytes for practical applications in phytoremediation, summarize alternative strategies for improving phytoremediation, discuss the fundamental mechanisms of endophyte-assisted phytoremediation, and present updated information regarding the advances, challenges, and new directions in the field of endophyte-assisted phytoremediation technology.
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•Endophytes are valuable bio-resources for enhancing phytoremediation efficiency.•The superiority of endophyte-assisted phytoremediation is assessed.•Mechanisms adopted by plant and endophyte for xenobiotic removal are summarized.•Cometabolism of plant and endophyte serves a main route for xenobiotic degradation.•“Omcs” techniques open up new perspectives for plant-endophyte interactions.
Frequent cyanobacterial blooms in the eutrophic waters produce a variety of toxins such as the monocyclic heptapeptide microcystins, greatly harming aquatic ecosystems and human health. However, ...little information of microcystins in agricultural fields is known. This field study of three common microcystin variants (MC-LR, MC-RR, and MC-YR) in vegetables (n = 161), soils (n = 161) and irrigation water samples (n = 23) collected from southern China regions affected by cyanobacteria blooms, shows their prevalence with total concentrations up to 514 μg/L water, 187 μg/kg soil (dry weight) and 382 μg/kg vegetable (fresh weight). MC-RR was the primary variant in all types of samples, accounting for 51.3–100% of total microcystin concentrations. Significant concentration-dependent correlations (p < 0.05) demonstrated that microcystin-contained irrigation waters were the major source of microcystin accumulation in both vegetables and soils. Meanwhile, intracellular-microcystins in irrigation water was found to play an important role in microcystins bioaccumulation in vegetables for the first time. Most vegetable samples (≥60%), particularly celery posed moderate or high human health risk via diet based on toxicity equivalents of the microcystins and reference dose for MC-LR (0.04 μg/kg/d), showing high food safety hidden dangers. Soil microcystins, especially MC-RR in 46.4–88.3% of soils could pose high ecological risks. This study highlights the potential high ecological and human health risks of microcystins in the real soil-vegetable systems of areas affected by cyanobacteria blooms, implying the profound significance and urgent need of investigation on microcystins in terrestrial ecosystems.
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•MCs are prevalent in actual soil-crop systems affected by cyanobacterial blooms.•MC-RR was the primary variant in all types of the samples.•Intracellular-MCs could play an important role in vegetable MCs accumulation.•Most vegetable samples posed moderate or high human health risk via diet.•Soil MCs, especially MC-RR could pose high ecological risks.
Cadmium (Cd)-contaminated rice imposes severe health risks to human. The present study investigated the role of arbuscular mycorrhizal fungi (AMF) in sculpting the rhizospheric bacterial community, ...and the potential effects on the Cd uptake by rice. AMF Funneliformis mosseae (Fm) or Rhizophagus intraradices (Ri) were inoculated to rice grown in soils spiked with 0 or 10 μM Cd. Initial Cd concentration in soil was 0.18 mg/kg. AMF colonization rate, plant biomass, Cd content in rice, soil properties, rice Cd transporters (Nramp5 and HMA3) and soil bacterial community were analysed. Both AMF decreased (P < 0.05) root and shoot Cd concentrations, especially for Ri treatment. The higher relative abundance of Actinobacteria (mostly from genus Arthrobacter) observed in Ri treatment probably absorbed Cd in soil, and hence decreased the Cd availability for rice. Expression of genes Nramp5 and HMA3 in root were lower in Ri treatment, but higher in Fm treatment. The gene expressions were in line with the results of lower root Cd content in Ri treatment, and higher in Fm treatment. The present study firstly revealed that AMF can reduce rice Cd uptake by changing the expression of Cd transporters and soil bacterial community in a pot experiment. Effects of plants-bacteria-fungi interaction on both plant productivity and toxicants uptake deserved further study.
•F. mosseae and R. intraradices decreased Cd concentrations in both root and shoot.•Cd transporters were suppressed by F. mosseae without Cd but promoted under Cd.•R. intraradices suppressed Nramp5 in all cases except under non-Cd condition.•Actinobacteria promoted by R. intraradices led to less extractable Cd in soil.•AM fungi exerted indirect and direct effects on reducing Cd uptake by rice.
Single extraction procedures (SEPs) have been extensively conducted to determine Cd bioavailability (Cd-Bav) in soils. However, whether SEPs can simultaneously predict Cd accumulation in crop grains ...and bioaccessibility (Cd-Bac) in soils remains unclear. To assess their suitability, the Cd-Bav in 20 contaminated soils (containing 0.27–56.59 mg/kg Cd) determined by four SEPs (including DTPA, EDTA, HOAc and HCl) was compared with Cd concentrations in crop grains (wheat and rice) and Cd-Bac in soils (based on SBET and PBET assays). The results indicated that both Cd-Bav (0–103.2%) and Cd-Bac (0–110.4%) in soils varied greatly with the methods used. The Cd-Bav obtained from chelators (DTPA and EDTA) was generally greater in low-Cd soils but lower in high-Cd soils as compared to those obtained from acid solutions (HOAc and HCl). Regression analysis revealed that bioavailable Cd concentrations in soils were linearly correlated with Cd concentrations in wheat grains (R2 = 0.88–0.91); however, no significant correlation was found for rice grains. The Cd-Bac in soils was significantly correlated with Cd-Bav obtained from HOAc (R2 = 0.55–0.59) or HCl (R2 = 0.60–0.68), but not with those obtained from chelators (DTPA and EDTA). Our data suggest that SEPs, particularly the HCl method, have great potential to simultaneously predict Cd accumulation in wheat grains and Cd-Bac in contaminated soils.
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•Both Cd-Bav and Cd-Bac vary remarkably with extraction methods and soils.•The Cd-Bav based on chelators is higher in low-Cd soils but lower in high-Cd soils compared to that based on acid solutions.•All four Cd-Bav predict well Cd levels in wheat grains, but not in rice grains.•Specifically, the HCl method also has great potential to predict Cd-Bac in soils.
The synergistic potential of plant essential oils (EOs) with other conventional and non-conventional antimicrobial agents is a promising strategy for increasing antimicrobial efficacy and controlling ...foodborne pathogens. Spoilage microorganisms are one of main concerns of seafood products, while the prevention of seafood spoilage principally requires exclusion or inactivation of microbial activity. This review provides a comprehensive overview of recent studies on the synergistic antimicrobial effect of EOs combined with other available chemicals (such as antibiotics, organic acids, and plant extracts) or physical methods (such as high hydrostatic pressure, irradiation, and vacuum-packaging) utilized to reduce the growth of foodborne pathogens and/or to extend the shelf-life of seafood products. This review highlights the synergistic ability of EOs when used as a seafood preservative, discovering the possible routes of the combined techniques for the development of a novel seafood preservation strategy.
The presence of chromium (Cr) in cultivated fields affects carbohydrate metabolism of rice (Oryza sativa L.) and weakens its productivity. Little is known about the molecular mechanism of sucrose ...metabolism underlying Cr stress response in rice plants. In the present study, the transcriptome map of sucrose metabolism in rice seedlings exposed to both trivalent and hexavalent chromium was investigated using Agilent 4 × 44K rice microarray analysis. Results indicated that Cr exposure (3 days) significantly (p < 0.05) improved sucrose accumulation, and altered the activities of sucrose synthetase, sucrose phosphate phosphatase, and amylosynthease in rice tissues. We identified 119 differentially regulated genes involved in 17 sucrose metabolizing enzymes and found that gene responses in roots were significantly (p < 0.05) stronger than in shoots under both Cr(III) and Cr(VI) treatment. The network maps of gene regulation responsible for sucrose metabolism in rice plants provide a theoretical basis for further cultivating Cr-resistant rice cultivars through molecular genetic improvement.
Tremendous amounts of food wastes are produced in China, and the conventional treatment by landfilling and incineration approaches poses serious environmental and social threats. Carbonization of ...food waste into value-added bio-solid is a feasible and potential alternative method for its sustainably recycle. Very limited information is available on the variation in biochar and hydrochar produced from food waste. In this study, five typical food waste types (eggshell, fish residue, breadcrumb, cooked rice and mixed food waste) and seven temperatures (200, 300, 400, and 500 °C for pyrolysis and 200, 250, and 300 °C for hydrothermal carbonization) were used, and physicochemical characteristics of the biochars and hydrochars were characterized. The main mass loss occurred centering at the temperatures of 270–320 °C, and 400 °C was a critical temperature for a complete decomposition. Physically, hydrochars showed spherically shaped morphological features in comparison with the pore and crack structures of biochars. Specific surface areas were generally low (<2 m2/g) for biochar and hydrochars produced from food wastes, except for biochar produced from mixed food waste at 500 °C (18 m2/g) and hydrochars produced from cooked rice at 300 °C (54 m2/g). In terms of chemical properties, hydrochars differed in pH, functional groups, elemental composition, proximate analysis compared with biochars. Hydrochars showed similar functional group types to that of biochars at low peak temperatures (≤300 °C), but the functional groups for biochars nearly disappeared at higher temperatures (≥400 °C). Hydrochars showed lower polarity and aromaticity than that of biochars. Hydrochars showed a lower pH and ash content than biochars due to the washout of inorganic components during hydrothermal carbonization. The results from this study proved the feasibility of recycling food wastes through pyrolysis and hydrothermal carbonization, and provided basic information for their potential utilization.
•Food wastes were converted into biochars and hydrochars through pyrolysis and hydrothermal carbonization.•Biochars and hydrochars produced from food wastes showed comparable properties compared with conventional biochars.•Na concentrations in biochar and hydrochars produced from food wastes were limited.
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