Effect of DBP/DEHP in vegetable planted soil on the quality of capsicum fruit

Uptake and accumulation of di(2-ethylhexyl) phthalate (DEHP) in a soil-ginseng system and toxicological mechanisms on ginseng (Panax ginseng C.A. Meyer)

Di(2-ethylhexyl) phthalate (DEHP) is regarded as a priority environmental pollutant. This study explored the adsorption and accumulation of DEHP within the ginseng-soil system and the mechanism of DEHP toxicity to ginseng (Panax ginseng C.A. Meyer). Under exposure to 22.10 mg/kg DEHP in soil, DEHP mainly accumulated in ginseng leaves (20.28 mg/kg), stems (4.84 mg/kg) and roots (2.00 mg/kg) after 42 days. The oxidative damage, metabolism, protein express of ginseng were comprehensively measured and analyzed. The results revealed that MDA presented an activation trend in ginseng stems and leaves after 42 days of DEHP exposure, while the opposite trend was observed for POD. Levels of ginsenoside metabolites Rg2, Rg3, Rg5, Rd, Rf and CK decreased in the ginseng rhizosphere exudates under DEHP stress. Further investigations revealed that DEHP disrupts ginsenoside synthesis by inducing glycosyltransferase (GS) and squalene synthase (SS) protein interactions. Molecular docking indicated that DEHP could stably bind to GS and SS by intermolecular forces. These findings provide new information on the ecotoxicological effect of DEHP on ginseng root.

Personal care products in soil-plant and hydroponic systems: Uptake, translocation, and accumulation

Personal care products (PCPs) are organic compounds that are incorporated in several daily life products, such as shampoos, lotions, perfumes, cleaning products, air fresheners, etc. Due to their massive and continuous use and because they are not routinely monitored in the environment, these compounds are considered emerging contaminants. In fact, residues of PCPs are being discharged into the sewage system, reaching wastewater treatment plants (WWTPs), where most of these compounds are not completely degraded, being partially released into the environment via the final effluents and/or accumulating in the sewage sludges. Environmental sustainability is nowadays one of the main pillars of society and the application of circular economy models, promoting the waste valorisation, is increasingly encouraged. Therefore, irrigation with reclaimed wastewater or soil fertilization with sewage sludge/biosolids are interesting solutions. However, these practices raise concerns due to the potential risks associated to the presence of hazardous compounds, including PCPs. When applied to agricultural soils, PCPs present in these matrices can contaminate the soil or be taken up by crops. Crops can therefore become a route of exposure for humans and pose a risk to public health. However, the extent to which PCPs are taken up and bioaccumulated in crops is highly dependent on the physicochemical properties of the compounds, environmental variables, and the plant species. This issue has attracted the attention of scientists in recent years and the number of publications on this topic has rapidly increased, but a systematic review of these studies is lacking. Therefore, the present paper reviews the uptake, accumulation, and translocation of different classes of PCPs (biocides, parabens, synthetic musks, phthalates, UV-filters) following application of sewage sludge or reclaimed water under field and greenhouse conditions, but also in hydroponic systems. The factors influencing the uptake mechanism in plants were also discussed.

Remediation of di(2-ethylhexyl) phthalate (DEHP) contaminated black soil by freeze-thaw aging biochar

Di(2-ethylhexyl) phthalate (DEHP), a complex structure with high toxicity, is a common organic pollutant. This study investigated the effects of fresh biochar (FBC), and freeze-thaw cycled aged biochar (FTC-BC) on DEHP-contaminated soils using a pot experiment. The specific surface area of FBC increased from 145.20 to 303.50 m2/g, and oxygen-containing functional groups increased from 1.26 to 1.48 mol/g after freeze-thaw cycles, greatly enhancing the adsorption of DEHP by biochar in the soil. The comprehensive radar chart evaluation showed that FBC and FTC-BC reduced DEHP growth stress and improved the soil properties. Compared with FBC, FTC-BC performed better in protecting the normal growth of pakchoi and improving soil properties. In addition, the application of biochar increased the diversity and abundance of bacteria in the DEHP-contaminated soil and changed the composition of the soil bacterial community. The partial least squares path model (PLS-PM) showed that adding biochar as a soil remediation agent significantly positively impacted soil nutrients and indirectly reduced the DEHP levels in soil and plants by increasing soil microbial diversity. Compared with FBC, FTC-BC creates a more satisfactory living environment for microorganisms and has a better effect on the degradation of DEHP in the soil. This study provides a theoretical basis for future biochar remediation of DEHP-contaminated soils in cold high-latitude regions.

Combined toxicity influence of polypropylene microplastics and di-2-ethylhexyl phthalate on physiological-biochemical characteristics of cucumber (Cucumis sativus L.)

Microplastics and di-2-ethylhexyl phthalate (DEHP) are prevalent and emerging pollutants in agro-ecosystem, raising concerns due to their widespread co-presence. Nevertheless, their combined toxicity on terrestrial plants remains largely unexplored. This study investigated the impact of polypropylene microplastics (MPs), DEHP, and their mixture on the physiological and biochemical characteristics of cucumber seedlings. The changes of membrane stability index (MSI), antioxidase activities, photosynthetic pigments and chlorophyll fluorescence in cucumber seedlings were assessed. The results demonstrated that MPs alone significantly inhibited MSI, photosynthetic pigments (Chl a, Chl b, and Chl a + b), Fm and qp of cucumber seedlings, and significantly promoted the carotene content and antioxidant enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) in cucumber seedlings. While DEHP alone significantly inhibited MSI and photosynthetic pigments of cucumber seedlings, and significantly promoted antioxidant enzyme activities in cucumber seedlings. Moreover, the combined toxicity of MPs and DEHP was found to be less pronounced than that of the single action of MPs and DEHP. The interaction between DEHP and MPs may contribute to the reduced toxicity. Abbott's modeling revealed that the combined toxicity systems were all antagonistic (RI < 1). Two-factor analysis and principal component analysis further confirmed that the treatment of MPs alone contributed the most to the toxicological effects of the physiological properties of cucumbers. In summary, this study highlighted the importance of understanding the combined effects of MPs and DEHP on plant physiology, providing insights for the development of effective treatments for emerging pollutants in agricultural ecosystems.

Environmental health risks induced by interaction between phthalic acid esters (PAEs) and biological macromolecules: A review

As a kind of compounds abused in industry productions, phthalic acid esters (PAEs) cause serious problems in natural environment. PAEs pollution has penetrated into environmental media and human food chain. This review consolidates the updated information to assess the occurrence and distribution of PAEs in each transmission section. It is found that micrograms per kilogram of PAEs are exposed to humans through daily diets. After entering the human body, PAEs often undergo the metabolic process of hydrolysis to monoesters phthalates and conjugation process. Unfortunately, in the process of systemic circulation, PAEs will interact with biological macromolecules in vivo under the action of non-covalent binding, which is also the essence of biological toxicity. The interactions usually operate in the following pathways: (a) competitive binding; (b) functional interference; and (c) abnormal signal transduction. While the non-covalent binding forces mainly contain hydrophobic interaction, hydrogen bond, electrostatic interaction, and π interaction. As a typical endocrine disruptor, the health risks of PAEs often start with endocrine disorder, further leading to metabolic disruption, reproductive disorders, and nerve injury. Besides, genotoxicity and carcinogenicity are also attributed to the interaction between PAEs and genetic materials. This review also pointed out that the molecular mechanism study on biological toxicity of PAEs are deficient. Future toxicological research should pay more attention to the intermolecular interactions. This will be beneficial for evaluating and predicting the biological toxicity of pollutants at molecular scale.

Occurrence, source, ecological risk, and mitigation of phthalates (PAEs) in agricultural soils and the environment: A review

The widespread distribution of phthalates (PAEs) in agricultural soils is increasing drastically; however, the environmental occurrence and potential risk of PAEs in agricultural systems remain largely unreviewed. In this study, the occurrence, sources, ecotoxicity, exposure risks, and control measures of PAEs contaminants in agricultural soils are summarized, and it is concluded that PAEs have been widely detected and persist in the soil at concentrations ranging from a few μg/kg to tens of mg/kg, with spatial and vertical variations in China. Agrochemicals and atmospheric deposition have largely contributed to the elevated contamination status of PAEs in soils. In addition, PAEs cause multi-level hazards to soil organisms (survival, oxidative damage, genetic and molecular levels, etc.) and further disrupt the normal ecological functions of soil. The health hazards of PAEs to humans are mainly generated through dietary and non-dietary pathways, and children may be at a higher risk of exposure than adults. Improving the soil microenvironment and promoting biochemical reactions and metabolic processes of PAEs are the main mechanisms for mitigating contamination. Based on these reviews, this study provides a valuable framework for determining future study objectives to reveal environmental risks and reduce the resistance control of PAEs in agricultural soils.

Phthalates - A family of plasticizers, their health risks, phytotoxic effects, and microbial bioaugmentation approaches

Phthalates are a family of reprotoxicant compounds, predominantly used as a plasticizer to improve the flexibility and longevity of consumable plastic goods. After their use these plastic products find their way to the waste disposal sites where they leach out the hazardous phthalates present within them, into the surrounding environment, contaminating soil, groundwater resources, and the nearby water bodies. Subsequently, phthalates move into the living system through the food chain and exhibit the well-known phenomenon of biological magnification. Phthalates as a primary pollutant have been classified as 1B reprotoxicants and teratogens by different government authorities and they have thus imposed restrictions on their use. Nevertheless, the release of these compounds in the environment is unabated. Bioremediation has been suggested as one of the ways of mitigating this menace, but studies regarding the field applications of phthalate utilizing microbes for this purpose are limited. Through this review, we endeavor to make a deeper understanding of the cause and concern of the problem and to find out a possible solution to it. The review critically emphasizes the various aspects of phthalates toxicity, including their chemical nature, human health risks, phytoaccumulation and entry into the food chain, microbial role in phthalate degradation processes, and future challenges.

Arthrobacter is a universal responder to di-n-butyl phthalate (DBP) contamination in soils from various geographical locations

Plasticizer phthalic acid esters (PAEs) are commonly found as contaminants in various soils. Previous studies indicated that their natural degradation can substantially differ among soil types; however, potential implications of the soil microbiome remained largely unexplored. Here, we have collected ten soil types from nine different geographical regions of China to investigate the degradation of DBP therein and role of bacteria in this process. Results showed that the degradation rate of DBP was lowest in nutrient-poor red soils from Jiangxi Province, while it was highest in fluvo-aquatic soil from Hebei Province. Bacterial community responses to DBP substantially differed in each of the analyzed soils. Arthrobacter is known for its broad-spectrum activity in terms of DBP degradation in soil and was therefore implemented as bioremediating inoculant in many polluted environments. In the present study, network analyses indicated that synergism between soil bacteria increased following exposure to DBP. Arthrobacter and Sphingomonas were found to expand their positive interactions with other members of the microbiome in DBP-contaminated soils. The overall findings of our study provide a basis for biomarker development for detection of DBP contaminations and an extended basis for future bioremediation approaches based on beneficial bacteria.

Biodegradation of di-(2-ethylhexyl) phthalate by novel Rhodococcus sp. PFS1 strain isolated from paddy field soil

Di-(2-ethylhexyl)-phthalate (DEHP) is the phthalate ester frequently utilized as a plasticizer, commonly found in cosmetics, packaging materials; moreover, it has carcinogenic and mutagenic effects on humans. In the current study, we isolated the soil bacterium Rhodococcus sp. PFS1 and to assess its DEHP degradation ability in various environmental conditions. The strain PFS1 was isolated from paddy field soil and identified by the 16S rRNA sequencing analyses. The strain PFS1 was examined for its biodegradation ability of DEHP at various pH, temperature, salt concentration, glucose concentration, and high and low concentrations of DEHP. Moreover, the biodegradation of DEHP at a contaminated soil environment by strain PFS1 was assessed. Further, the metabolic pathway of DEHP degradation by PFS1 was analyzed by HPLC-MS analysis. The results showed that the strain PFS1 effectively degraded the DEHP at neutral pH and temperature 30 °C; moreover, expressed excellent DEHP degradation at the high salt concentration (up to 50 g/L). The strain PFS1 was efficiently degraded the different tested phthalate esters (PAEs) up to 90%, significantly removed the DEHP contamination in soil along with native organisms which are present in soil up to 94.66%; nevertheless, the PFS1 alone degraded the DEHP up to 87.665% in sterilized soil. According to HPLC-MS analysis, DEHP was degraded into phthalate (PA) by PFS1 strain via mono(2-ethylehxyl) phthalate (MEHP); then PA was utilized for cell growth. These results suggest that Rhodococcus sp. PFS1 has excellent potential to degrade DEHP at various environmental conditions especially in contaminated paddy field soil.

Fe-Mn oxide modified biochar decreases phthalate uptake and improves grain quality of wheat grown in phthalate-contaminated fluvo-aquic soil

We used a pot experiment to investigate the effectiveness of 0.5, 1.0, and 2.0% biochar (BC) or iron-manganese oxide modified biochar (FMBC) additions on the biomass, enzyme activity, and grain quality of wheat plants grown in dibutyl phthalate (DBP) and di-(2-ethylhcxyl) phthalate (DEHP) polluted fluvo-aquic soils, as well as the bioavailability of DBP and DEHP. BC and FMBC applications significantly reduced DBP and DEHP accumulation in grains, which enhanced the content of starch and protein-related enzyme, thereby improving yield, and starch and protein content in wheat grains and increasing the content of minerals including Fe, Mn, K and Ca. Molecular docking assays showed that DBP and DEHP could bind to starch synthase (GBSS) through hydrogen bonds and intermolecular forces, which may have hindered the entry of substrates or occupied the binding sites of the reactants, thus inhibiting the activity of GBSS. In addition, FMBC treatment had a better inhibitory effect on the phytotoxicity of DBP and DEHP on wheat grain than BC treatment. This result might be attributed to the fact that FMBC has more functional groups and porous structure, and larger specific surface area. In summary, these findings contribute to our understanding of the mechanism of phthalate phytotoxicity, which may help us prevent/reduce it in the future.

Simultaneous removal of nitrogen and dimethyl phthalate from low-carbon wastewaters by using intermittently-aerated constructed wetlands

Phthalic acid esters (PAEs) such as dimethyl phthalate (DMP) have been widely used as a plasticizer in society, which pose severe harm to human health. In this study, the potential of DMP elimination and nitrogen removal from low-carbon wastewaters by intermittently-aerated subsurface flow constructed wetlands (SSFCWs) was evaluated, and the effect of the influent DMP concentrations on nitrogen removal was also investigated. The results showed a better removal of DMP (88.5-97.8%) was obtained in CWs under different influent DMP concentrations, and the high removal of COD (86.7-95.0%) and NH₄⁺-N (95.5-98.7%) was also achieved simultaneously. The maximum TN removal (48.7%) was observed at an influent DMP concentration of 10 mg L^-1. Furthermore, the TN removal and DMP reduction had a good fitting relationship (R² = 0.71) in CWs under different influent DMP concentrations. The analysis of DMP decomposition processes demonstrated that DMP was degraded into some smaller molecular fractions, and DMP degradation intermediates mainly including monomethyl phthalate (MMP) and phthalate (PA), which might provide a potential carbon source for the denitrification processes in CWs. These findings could contribute to a better understanding of DMP removal mechanism and provide useful guidance for the practical application of CWs for treating wastewater containing phthalates.

Biochemical pathways and enhanced degradation of dioctyl phthalate (DEHP) by sodium alginate immobilization in MBR system

As one of the most representative endocrine disrupting compounds, dioctyl phthalate (DEHP) is difficult to remove due to its bio-refractory characteristic. In this study, an immobilization technology was applied in an MBR system to improve the degradation of DEHP. The degradation efficiency of DEHP was significantly improved and the number of degradation genes increased by 1/3. A bacterial strain that could effectively degrade DEHP was isolated from activated sludge and identified as Bacillus sp. The degradation pathway of DEHP was analyzed by GC-MS. DEHP was decomposed into phthalates (DBP) and Diuretic sylycol (DEP), then further to Phthalic acid (PA). PA was oxidized, dehydrogenated, and decarboxylated into protocatechins, further entered the TCA cycle through orthotopic ring opening. The DEHP degrading strain was immobilized by sodium alginate and calcium chloride under the optimized immobilization conditions, and added to MBR systems. The removal rate of DEHP (5 mg/L) (91.9%) and the number of 3, 4-dioxygenase gene copies was significantly improved by adding immobilized bacteria. Micromonospora, Rhodococcus, Bacteroides and Pseudomonas were the dominant genuses, and the results of bacterial community structure analysis show that immobilization technology is beneficial to system stability. The results showed the potential applications of the immobilized technique in DEHP wastewater treatment in MBR.

Improving yield and quality of vegetable grown in PAEs-contaminated soils by using novel bioorganic fertilizer

Phthalate acid esters (PAEs) are ubiquitous pollutants in agricultural soils. Application of bioorganic fertilizer (BOF) containing beneficial microbes represents a promising approach to improve the yield and quality of crops grown in contaminated soils. In the present study, a novel multifunctional bioorganic fertilizer N-BOF was developed by using compost of sewage sludge and agricultural waste and inoculating with PAEs-degrading B. megaterium YJB3 and phosphate solubilizing B. megaterium YLYP1. Its feasibility of improving the yield and quality of vegetable grown in PAEs (including DBP and DEHP) contaminated soil was evaluated by pot experiments. The N-BOF could effectively promote plant growth, with biomass increasing by 4-66.9% and 19-110% compared to chemical (CF) and no fertilizer (CK), respectively. The concentrations of DBP and DEHP in shoots of chemically fertilised vegetable ranged 1.23-3.12 mg/kg (dry weight, DW) and 1.63-3.89 mg/kg (DW), respectively. Their concentrations were significantly decreased (p < 0.05) when N-BOF was applied (1%, 2%, 5% amendment), especially at higher application rate ranging 0.11-0.3 mg/kg (DW) and 0.16-0.32 mg/kg (DW), respectively. Meanwhile, vegetable quality attributes were also significantly improved when 2% N-BOF was applied, with increase in the contents of vitamin C, vitamin B1, total protein, and starch, and decrease in the contents of nitrite and nitrate. In this case, the human health risk from consumption of the vegetable grown in PAEs-contaminated soil could be significantly reduced. Thus, our study is expected to provide an efficient way of high-value utilization of organic substrates by producing low-cost but high quality N-BOF. Future studies on the effects of N-BOF in terms of fertilizer regimes on yield and quality of the vegetable are needed, and further field studies for assessing the long-term efficacy and reliability of this promising N-BOF are also warranted.

Uptake and toxicity of di-(2-ethylhexyl) phthalate in Brassica chinensis L

This work focuses on the bioaccumulation and toxic effects of di-(2-ethylhexyl) phthalate (DEHP) in the leafy vegetable Shanghaiqing (SHQ) (Brassica chinensis L.). The accumulated DEHP amount in the edible part and roots of SHQ increased as the DEHP concentration in the soil increased. DEHP accumulation was higher in the roots than in the edible part of the plant. The root concentration factors and bioaccumulation factors for DEHP in SHQ were 0.13-2.49 and 0.03-2.00, respectively. The DEHP translocation factors were below 1.0, indicating that DEHP preferentially accumulated in plant roots. The DEHP risk index in the edible part of SHQ in relation to the human body and in terms of dietary exposure risk assessment was also below 1.0, indicating a low health risk. High DEHP concentrations caused 1) inhibition of SHQ growth, 2) an increase in SHQ chlorophyll and malondialdehyde contents and 3) a decrease in soluble sugar and vitamin contents. Low DEHP concentrations stimulated total superoxide dismutase, peroxidase and catalase activities, while high DEHP levels showed an inhibitory effect. DEHP presence in soil affected not only SHQ growth but also quality. Our results provide the data needed for the proper assessment of food safety and the ecological impact of DEHP contamination in agricultural soils.

Accumulation and transport patterns of six phthalic acid esters (PAEs) in two leafy vegetables under hydroponic conditions

In this study, we investigated the accumulation and transport patterns of six phthalic acid esters (PAEs) in two leafy vegetables under hydroponic conditions. The tested PAEs included dibutyl phthalate (DBP), diethyl phthalate (DEP), diallyl phthalate (DAP), diisobutyl phthalate (DIBP), dimethyl phthalate (DMP) and benzyl butyl phthalate (BBP), and the tested vegetables included Gaogengbai and Ziyoucai. The results revealed that the six PAEs were taken up by vegetables from the solution, although their accumulation and distribution varied among PAEs. The ability of concentrating PAEs into the roots followed the order of BBP > DBP > DIBP > DAP > DEP > DMP, whereas the ability of concentrating PAEs in plant shoots had the opposite order. By analysing the fractionation of the six PAEs in vegetable roots, DMP had the largest proportion in terms of apoplastic movement, while BBP had the largest proportion in terms of symplastic movement. Correlation analyses revealed that the differences among the accumulation and distribution behaviours of the six PAEs in plant tissues were not only related to their physicochemical parameters, such as alkyl chain length and the octanol/water partition coefficient (logK_ow), but also related to the proportion of apoplastic and symplastic movement in the plant roots. In addition, PAEs were more readily accumulated in the Gaogengbai roots than in the Ziyoucai roots; however, the opposite trend was observed for the shoots.

Partition and Fate of Phthalate Acid Esters (PAEs) in a Full-Scale Horizontal Subsurface Flow Constructed Wetland Treating Polluted River Water

When used as highly produced chemicals and widely used plasticizers, Phthalate acid esters (PAEs) have potential risks to human life and the environment. In this study, to assess the distribution and fate of PAEs, specifically inside a full-scale horizontal subsurface flow constructed wetland, four PAEs including dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and bis (2-ethylhexyl) phthalate (DEHP) were investigated. In effluent, PAEs concentration decreased 19.32% (DMP), 19.18% (DEP), 19.40% (DBP), and 48.56% (DEHP), respectively. Within the wetland, PAEs partitioned in water (0.18–1.12 μg/L, 35.38–64.92%), soil (0.44–5.08 μg/g, 1.02–31.33%), plant (0.68–48.6 μg/g, 0.85–36.54%), air and biological transformation (2.72–33.21%). The results indicated that soil and plant adsorption contributed to the majority of PAE removal, digesting DMP (19.32%), DEP (19.18%), DBP (19.40%), and DEHP (48.56%) in constructed wetlands. Moreover, the adsorption was affected by both octanol/water partition coefficient (Kow) and transpiration stream concentration factors (TSCF). This work, for the first time, revealed the partition and fate of PAEs in constructed wetlands to the best of our knowledge.

Mechanistic studies of congener-specific adsorption and bioaccumulation of polycyclic aromatic hydrocarbons and phthalates in soil by novel QSARs

Polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) which are structurally featured with one or more aromatic skeletons are often regarded as two important groups of organic pollutants due to the widespread distribution and notorious toxic effects in soils. Relative to the great number of structural analogues or congeners detected in soil, however, the soil adsorption and bioaccumulation of PAHs/PAEs by plant is far less studied for the insufficiency of experimental determinations or lack of insights into the inherent structural requirements. To mechanistically evaluate the congener-specific soil adsorption and bioaccumulation for PAHs/PAEs, the quantitative structure-activity relationships (QSARs) were successfully developed by density functional theory (DFT) computation and partial least squares (PLS) analysis. As verified with the higher cumulative variance coefficients and cross-validated correlation coefficients for strong stability, interpretability and predictability, the QSARs could be used for prediction of unknown adsorption potency or bioavailability within the specified applicability domain, respectively. It was indicated by QSAR that the structural requirements of PAHs/PAEs necessary for strengthening the soil adsorption were mainly attributed to the molecular polarizability and the associated dispersion interaction with soil. As regards the bioaccumulation by carrot, the aggravation of spherical polarity change of molecules and the involved electrostatic interaction with soil entity or electron transfer from the highest occupied molecular orbital (HOMO) of PAHs/PAEs was implied to be inherently decisive for the variance of bioavailability among congeners. Based on the holistic view of negative correlation relationship, the soil adsorption seemed to act as the forceful constraint in decreasing the bioaccumulation of PAHs/PAEs and could also be alternatively gauged as the preliminary evaluation of bioavailability and risks on soil ecosystem. It would thus help better understand the soil adsorption and bioaccumulation with the informative mechanistic insights and provide data support for ecological risk assessment of PAHs/PAEs in soils.

Uptake and accumulation of di-n-butyl phthalate in six leafy vegetables under hydroponic conditions

Abstract

The uptake and accumulation of di-n-butyl phthalate (DBP) in six leafy vegetables was investigated under hydroponic conditions. The test vegetables were six varieties of Brassica campestris ssp., including Kangresijiqing (KRSJQ), Xiadiqing (XDQ), Ziyoucai (ZYC), Aijiaohuang (AJH), Shanghaiqing (SHQ) and Gaogengbai (GGB). The root concentration factor (RCF), translocation factor (TF) and transpiration stream concentration factor (TSCF) were calculated in order to compare the difference of uptake and accumulation behaviours of DBP in vegetable varieties. The results showed that DBP was easily concentrated in vegetable roots, but was poorly translocated from the roots to the shoots. Among the six vegetables, the ability of concentrating DBP from the solution to shoots was the highest in GGB, followed by ZYC, KRSJQ, AJH, SHQ and XDQ. High concentrations of DBP (5.0 mg/L) seem to inhibit normal physiological activity in the vegetables, which resulted in a higher RCF and a lower TF and TSCF than in low-concentration treatment. The results will help to evaluate the safety of agricultural products and to provide evidence for screening DBP pollution-safe vegetable cultivars.

Graphical abstract

Effects of Phthalate Esters on Ipomoea aquatica Forsk. Seedlings and the Soil Microbial Community Structure under Different Soil Conditions

Phthalate acid esters (PAEs) are the most frequently utilized synthetic chemical compounds worldwide. They are typical emergent contaminants and are currently attracting considerable concern due to their risks to plants, animals, and public health. Determining the vital environmental factors that affect the toxicity of target pollutants in soil is important for vegetable production and the maintenance and control of soil productivity. We investigated the influence of di-n-butyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) under different soil conditions on physiological changes in water spinach (Ipomoea aquatic Forsk.) seedlings and the rhizosphere soil microbial community. Supported by our former experiments in which we determined the representative concentrations that caused the most pronounced toxic effects, three experimental concentrations were studied including control soils without PAEs and spiked soils with either 20 mg DBP or DEHP kg⁻¹ soil. The soil at all the three PAE concentrations was then adjusted to test two soil pH values, three levels of soil organic matter (SOM) content, and three levels of soil moisture content; thus, we completed 12 treatments or conditions simulating different soil environment conditions in greenhouses. After 30 days of cultivation, we analyzed the toxicity effects of two target PAEs on plant growth and physiological factors, and on soil microbial community characteristics. The toxicity of soil DBP and DEHP to the physiology of water spinach was found to be most affected by the soil pH value, then by SOM content, and least of all by soil moisture. The results of the 454 high-throughput sequencing analysis of the soil microbial community indicated that the toxicity of target PAEs to soil microorganisms was most affected by SOM content and then by soil moisture, and no clear relationship was found with soil pH. Under different soil conditions, declines in leaf biomass, chlorophyll a content, and carotenoid content—as well as increases in free amino acid (FAA) content, superoxide anion free radical activity, and hydroxyl radical activity—occurred in response to DBP or DEHP. Heavy use of chemical fertilizer, organic fertilizer, and high humidity led to the special environmental conditions of greenhouse soil, constituting the main conditions considered in this study. The results indicate that under the special highly intensive production systems of greenhouses, soil conditions may directly influence the effects of pollutant phytotoxicity and may thus endanger the yield, nutrient content, and food safety of vegetables. The combined studies of the impacts on plants and rhizosphere microorganisms give a more detailed picture of the toxic effects of the pollutants under different soil conditions.

Effect of biochars on the bioavailability of cadmium and di-(2-ethylhexyl) phthalate to Brassica chinensis L. in contaminated soils

Soil co-contamination of potentially toxic elements (PTEs) and phthalate esters has become prominent due to its potential adverse effect on human food supply. There is limited information on using wood- and animal-derived biochars for the remediation of co-contaminated soils. Therefore, a pot experiment was conducted using Brassica chinensis L. as a bio-indicator plant to investigate the effect of P. orientalis biochar and pig biochar application on the bioavailability of cadmium (Cd) and di-(2-ethylhexyl) phthalate (DEHP) and on plant physiological parameters (malondialdehyde, proline and soluble sugars). Biochar materials were applied to two soils containing low (LOC) and high (HOC) organic carbon content at rates of 0, 0.5, 1, 2, and 4%. To better understand the influence of biochar, physicochemical properties and X-ray diffraction (XRD), energy dispersive X-ray spectrometry (EDS), Fourier transform-infrared spectrometry (FTIR), scanning electron microscopy (SEM) were characterized. Biochar application increased soil pH, organic carbon content, and available phosphorus content. Increasing biochar application rates decreased DTPA-extractable Cd and extractable DEHP concentrations in both soils. Biochar application reduced the plant uptake of both Cd and DEHP from co-contaminated soils; the maximum reduction of Cd (92.7%) and DEHP (52.0%) was observed in 2% pig biochar-treated LOC soil. The responses of plant physiological parameters to increased biochar applications indicated that less Cd and DEHP were taken up by plants. Pig biochar was more effective (P < 0.05) at reducing the bioavailability of Cd and DEHP in both soils than P. orientalis biochar; therefore, pig biochar had greater potential for improving the quality of the crop. However, the highest application rate (4%) of pig biochar restricted plant seed germination. Key factors influencing the bioavailability of Cd and DEHP in soils were soil organic carbon content, biochar properties (such as surface alkalinity, available phosphorus content and ash content) and biochar application rates.

The drivers of bacterial community underlying biogeographical pattern in Mollisol area of China

In order to better understand the composition and driving factors of the bacterial community in Mollisols, we selected 9 representative facility agricultural lands in Mollisol area of China for sampling, and described it on a larger spatial scale. Soil bacterial community structure in these 9 regions (determined by high-throughput sequencing analysis) showed significant differences at the genus level. The correlation between bacterial community composition and soil properties, contaminants and geographical latitude showed that the diversity of bacterial community was still strongly correlated with pH and SOM under the influence of phthalates (P < 0.05). Principal component Analysis (PCA) showed that soil properties (i.e. pH, organic matter, stacking density, the content of nitrogen, potassium, phosphorus) and PAEs level rather than geographic latitude were main drivers of differences in bacterial community structure. These factors account for 73.04% of the total variation of the bacterial community. Among them, PAEs act as a typical pollutant is the main factor driving the composition of bacterial community in facility agriculture Mollisols. This shows that PAEs is a potential pollution risk factor, which has important guiding significance for the sustainable and healthy development of agriculture in Mollisol area.

Di-(2-ethylhexyl) phthalate (DEHP)-induced hepatotoxicity in quail (Coturnix japonica) via suppression of the heat shock response

Di-(2-ethylhexyl) phthalate (DEHP) is a widespread environmental toxicant that severely impacts agricultural production and animal and human health. Nevertheless, DEHP-induced hepatotoxicity at the molecular level in quail remains unexplored. The heat shock response (HSR), involving heat shock proteins (HSPs) and heat shock transcription factors (HSFs), is a highly conserved molecular response that is triggered by stressors, especially exposure to toxicants. To explore the DEHP-induced hepatotoxicity that occurs via regulation of HSR in birds, female quail were dosed with DEHP by oral gavage (0, 250, 500 and 1000 mg/kg) for 45 days. Based on histopathological analysis, the livers of the DEHP-treated groups exhibited structural alterations of hepatocytes, including mitochondrial swelling, derangement of hepatic plates, inflammatory cell infiltration and adipose degeneration. Ultrastructural evaluation of the livers of DEHP-treated quail revealed swollen mitochondria, partial disappearance of mitochondrial membranes and cristae, nuclear chromatin margination and nuclear condensation. The expression of HSF1 and HSF3 significantly decreased after DEHP exposure. The levels of HSPs (HSP10, HSP25, HSP27, HSP40, HSP47, HSP60, HSP70 and HSP90) were significantly downregulated in the livers of DEHP-treated quail. In this study, we concluded that DEHP exposure resulted in liver function damage and hepatotoxicity by reducing the expression of HSFs and HSPs in quail liver, which inhibited the protective effect of the HSR signaling pathway.

Modulation of biochemical and physiological parameters in Hordeum vulgare L. seedlings under the influence of benzyl-butyl phthalate

Background

Phthalates are man-made chemical compounds with numerous applications especially known for their use as plasticizers. They have weak bonding to the polymeric matrix or products in which they are used. Owing to this reason, they are readily released into the environment which makes them ubiquitous. The agricultural soils are also reported to be polluted with phthalates up to a considerable extent which causes adverse effects on flora and fauna. A few studies have been conducted on phthalate-induced phytotoxicity, which has revealed that phthalates affect the quality and yield of edible plants. In the last decades, some crops were analyzed for phthalate-induced adversities; among them, barley was the least explored.

Methods

The present study has investigated the impact of benzyl-butyl phthalate (BBP) on barley (Hordeum vulgare L.) seedlings to address the biochemical, physiological consequences, and toxicological implications. After the exogenous exposure of BBP (viz. 0, 25, 50, 100, 200, 400, 800, 1,600 mg/L) for 7 days, barley seedlings were analyzed for different indices.

Results

The exposure of BBP mediated a significant (p ≤ 0.05, 0.01) overall elevation in the contents of pigment, proline, soluble protein, carbohydrate, hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) in shoots and roots of barley seedlings. The activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) were also stimulated significantly in shoots and roots of seedlings against BBP stress except for SOD activity which declined in the roots. The polyphenols (non-enzymatic antioxidants) content was also altered in all the treated concentrations as compared to the control. Furthermore, BBP caused stomatal abnormalities, induced cytotoxicity, and loss of plasma membrane integrity.

Conclusions

BBP disturbed the normal physiology of barley which could also affect the yield of the crop under field conditions.

Characterization of Di-n-Butyl Phthalate Phytoremediation by Garden Lettuce (Lactuca sativa L. var. longifolia) through Kinetics and Proteome Analysis

Di-n-dutyl phthalate (DBP), an endocrine disruptor, is one of the most widely used phthalate esters (PAEs) in the world. It can be accumulated in seafood or agricultural products and represents a substantial risk to human health via the food chain. Thus, finding a plant which can remediate DBP but have no effects on growth is the main topic of the development of DBP phytoremediation. This study used garden lettuce (Lactuca sativa L. var. longifolia), which has a significant DBP absorption capability, as a test plant to measure phytoremediation kinetics and proteome changes after being exposed to DBP. The results show that DBP accumulated in different parts of the garden lettuce but the physiological status and morphology showed no significant changes following DBP phytoremediation. The optimal condition for the DBP phytoremediation of garden lettuce is one critical micelle concentration (CMC) of non-ionic surfactant Tween 80 and the half-life (t1/2, days), which calculated by first-order kinetics, was 2.686 days for 5 mg L−1 of DBP. This result indicated that the addition of 1 CMC of Tween 80 could enhance the efficiency of DBP phytoremediation. In addition, the results of biotoxicity showed that the median effective concentration (EC50) of DBP for Chlorella vulgaris is 4.9 mg L−1. In this case, the overall toxicity markedly decreased following phytoremediation. In the end, the result of proteome analysis showed six protein spots, revealing significant alterations. According to the information of these proteomes, DBP potentially causes osmotic and oxidative stress in garden lettuce. In addition, since DBP had no significant effects on the morphology and physiological status of garden lettuce, garden lettuce can be recommended for use in the plant anti-DBP toxicity test, and also as the candidate plant for DBP phytoremediation. We hope these findings could provide valuable information for DBP-contaminated water treatment in ecological engineering applications or constructed wetlands.

Toxicity of phthalate esters to lettuce (Lactuca sativa) and the soil microbial community under different soil conditions

Phthalate esters (PAEs) are globally used plasticizers and typical endocrine disruptors that can readily accumulate in agricultural products and represent a substantial risk to human health via the food chain. The range of soil properties has an important influence on the expression of PAE toxicity, and the mechanisms by which soil physical and chemical properties affect the expression of toxicity of target PAEs to plants and microorganisms requires further investigation. Important soil factors affecting the eco-toxicological effects of two typical PAEs, di-n-butyl phthalate (DnBP) and bis (2-ethylhexyl) phthalate (DEHP), on lettuce (Lactuca sativa) in a spiked soil were investigated in the present study. Soil at various pH values was spiked with three PAE concentrations (1, 5 and 20 mg DnBP or DEHP kg-1 soil), organic matter contents and water holding contents to simulate the greenhouse soil environment for 30 days. Their influence on the biomass, photosynthetic pigment contents, various physiological changes and soil microbial communities was determined as endpoints. The toxicity to lettuce of DnBP was higher than that of DEHP in the soil and soil pH was the most important factor affecting their single toxicity, followed by soil organic matter content and soil moisture content in agreement with the Biolog test results. Under different soil conditions total protein, total soluble sugar and free amino acid contents were positively correlated with concentrations of the target PAEs, but leaf area, biomass, •O2- activity, vitamin C content and soil microbial diversity indices showed the opposite trend. Chlorophyll a and carotenoid contents were more inhibited by DnBP together with impacts on indices of soil microbial diversity. The results suggest that soil conditions in greenhouses directly explain the patterns of pollutant toxicity displayed and impact the quantity, quality and food safety of vegetables produced using highly intensive production systems.

Photosynthetic and antioxidant response of wheat to di(2-ethylhexyl) phthalate (DEHP) contamination in the soil

Di(2-ethylhexyl) phthalate (DEHP) is a commonly used, artificially-synthesized, industrial chemical that can be released into the soil. However, to date, there is no comprehensive study on the effects of DEHP on photosynthesis, induction of reactive oxygen species, and response of the antioxidant defense system in wheat plants growing in DEHP contaminated soil. This study was conducted to address this gap in knowledge. Our results showed that after application of 10, 20, and 40 mg/kg DEHP, photosynthetic parameters, fluorescence parameters, and chlorophyll content of wheat leaves at seedling, jointing, and booting stages decreased, while the intercellular carbon dioxide concentration increased. This indicates that the observed decrease in net photosynthetic rate in wheat leaves was due to a non-stomatal limitation, wherein DEHP seems to have hindered the photoelectron transfer process. Both superoxide anion (O₂^-) and hydrogen peroxide (H₂O₂) content increased in the roots, stems, and leaves in plant under DEHP treatment compared with those in the control plants. Antioxidant enzyme activity increased with increasing DEHP stress, except under the 40 mg/kg treatment at the seedling stage. The antioxidant system had a certain protective effect on wheat, but DEHP still caused peroxidation of cell membrane lipids. The extent of DEHP damage to the roots, stems, and leaves was concentration dependent. Furthermore, enzymatic activity tolerance increased with metabolism, and long-term effects of DEHP gradually decreased with plant growth. Finally, the toxic effects of DEHP on root tissues were more serious at the seedling and jointing stages.

Fate of di (2‑ethylhexyl) phthalate in different soils and associated bacterial community changes

Di (2‑ethylhexyl) phthalate (DEHP) is a ubiquitous organic pollutant, which has caused considerable pollution in arable soils. In this study, the relationship between DEHP degradation potential and soil properties in 12 agricultural soils (S1-S12) was examined in a microcosm based experiment. Six of these soils were then selected to monitor patterns in bacterial community responses. It was found that DEHP degradation was positively correlated with bacterial counts in the original soils, suggesting a key role for bacteria in degradation. However, DEHP metabolism did not always lead to complete degradation. Its monoester metabolite, mono (2‑ethylhexyl) phthalate (MEHP), was present at appreciable levels in the two acidic soils (S1 and S2) during the incubation period of 35 days. Based on high-throughput sequencing data, we observed a greater impact of DEHP contamination on bacterial community structure in acidic soils than in the other soils. Nocardioides, Ramlibacter and unclassified Sphingomonadaceae were enriched in the two near-neutral soils where degradation was highest (S4 and S7), suggesting that these organisms might be efficient degraders. The relative abundance of Tumibacillus was greatly reduced in 50% of the six soils examined, demonstrating a high sensitivity to DEHP contamination. Furthermore, putative organic-matter decomposing bacteria (including Tumebacillus and other bacteria taxa such as members from Micromonosporaceae) were greatly reduced in the two acidic soils (S1 and S2), possibly due to the accumulation of MEHP. These results suggest a crucial role of soil acidity in determining the fate and impact of DEHP in soil ecosystems, which deserves further investigation. This work contributes to a better understanding of the environmental behavior of DEHP in soil and should facilitate the development of appropriate remediation technologies.

The joint toxicity effect of five antibiotics and dibutyl phthalate to luminescent bacteria (Vibrio fischeri)

Antibiotics and phthalate esters are two kinds of emerging pollutants and are ubiquitous in the aquatic ecosystem. To date, few studies analyzed the combined toxicity of the mixtures of antibiotics and phthalate esters, and their joint toxicity effect mode remains unknown. Here, we investigated the single and joint toxicity of dibutyl phthalate (DBP) and five antibiotics, namely, oxytetracycline hydrochloride (OTC), chlortetracycline hydrochloride (CTC), sulfamethazine (SMZ), sulfamerazine (SMR), and sulfadiazine (SD), to luminescent bacteria of Vibrio fischeri. The median effect concentration (EC₅₀) values of the test chemicals were ranked as CTC (6.67 mg/L) > OTC (25.12 mg/L) > SD (67.61 mg/L) > SMR (141.51 mg/L) > DBP (148.38 mg/L) > SMZ (245.07 mg/L). The joint toxicities of the binary mixtures of antibiotics and DBP were evaluated by the concentration addition (CA) and independent action (IA) models. The joint toxicity effects of CTC-DBP, OTC-DBP, SMZ-DBP, SMR-DBP, and SD-DBP all appeared to be synergism. Our study revealed that sulfonamides combined with DBP could be as toxic as or even more toxic than tetracycline. Thus, the joint toxicity effect should be considered when assessing the ecological risks of binary or multicomponent pollutants.

Pollution characteristics and health risk assessment of phthalate esters in urban soil in the typical semi-arid city of Xi'an, Northwest China

A total of 62 urban soil samples were collected in the city of Xi'an in Northwest China, and analyzed for six U.S. Environmental Protection Agency priority phthalate esters (PAEs). Unlike earlier studies on PAEs in agricultural soil as well as urban soil in humid climates, this paper for the first time comprehensively assessed pollution characteristics and health risks of human exposure to PAEs in urban soil in a typical semi-arid climate. The total concentrations of the six PAEs (Σ6PAEs) in the urban soil varied between 193.0 and 19146.4 μg kg^-1 with a mean of 1369.3 μg kg^-1. The PAEs were dominated by di-n-butyl phthalate and di(2-ethylhexyl) phthalate. Magnetic susceptibility and soil texture were controlling factors influencing the concentrations of PAEs in the urban soil. The concentrations of benzyl butyl phthalate, di(2-ethylhexyl) phthalate, and Σ6PAEs increased from the first to third ring roads, while the concentrations of di-n-octyl phthalate decreased. Relatively higher levels of PAEs were observed in industrial, traffic, and residential areas. The PAEs in the urban soil originated mainly from the application of plasticizers or additives, use of cosmetics and personal care products, emissions of construction materials and home furnishings, industrial processes, and atmospheric deposition. The concentrations of some PAEs in the urban soil exceeded soil allowable concentrations and environmental risk levels. The non-cancer and carcinogenic risks of human exposure to the PAEs were relatively low.

Effects of clay minerals on diethyl phthalate degradation in Fenton reactions

Phthalate esters are a group of plasticizers, which are commonly detected in China's soils and surface water. Fenton reactions are naturally occurring and widely applied in the degradation of contaminants. However, limited research was considered the effects of clay minerals on contaminants degradation with OH oxidation. In this study, batch experiments were conducted to investigate the degradation of diethyl phthalate (DEP) in Fenton reactions in the presence of clay minerals, and the effects of clay type, Fe content in clay structure. The results showed the clay adsorption inhibited total degradation of DEP, and Fe content in clay structure played an important role in DEP degradation, including in solution and adsorbed in clay minerals. Clay minerals with less Fe content (<3%) quenched OH radical, while nontronite with Fe content 19.2% improved OH radical generation and accelerated DEP degradation in solution. The degradation of clay-adsorbed DEP was much slower than DEP in solution. Six main products of DEP degradation were identified, including monoethyl phthalate, phthalate acid, hydroxyl diethyl phthalate, etc. This study implied that phthalate ester's degradation would be much slower in natural water than expected in the presence of clay minerals.

Joint Toxicity of Two Phthalates with Waterborne Copper to Daphnia magna and Photobacterium phosphoreum

Di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) are two widely used phthalates, while Cu(II) is a common valence state of copper. They have been ubiquitously detected in the aquatic environment, but information on their joint toxicity to aquatic organisms is scarce. In this study, we evaluated the combined effects of copper and these two phthalates to Daphnia magna and Photobacterium phosphoreum by quantifying the acute toxicity expressed by the EC50 (the concentration causing 50 % of maximal effect) value. The toxicity order was DEHP + Cu(II) > DBP + Cu(II) > Cu(II) > DEHP > DBP for both test species. Antagonism effects were found in the joint toxicity of Cu(II) combined with DBP or DEHP using the toxic unit method. These findings have important implications in environmental risk assessment for phthalates in the aquatic environment in the presence of heavy metals.

Oxidative Stress, Cytotoxicity and Genotoxicity in Earthworm Eisenia fetida at Different Di-n-Butyl Phthalate Exposure Levels

Recognized as ubiquitous contaminants in soil, the environmental risk of phthalic acid esters (PAEs) is of great concern recently. Effects of di-n-butyl phthalate (DnBP), an extensively used PAE compound to Eisenia fetida have been investigated in spiked natural brown yellow soil (Alfisol) for soil contact test. The toxicity of DnBP to E. fetida on the activity of superoxide dismutase (SOD) activity, peroxidase (POD), reactive oxygen species (ROS) content, and the apoptosis of coelomocytes and DNA damage at the 7th, 14th, 21st and 28th day of the incubation have been paid close attention to. In general, SOD activity and ROS content were significantly induced, opposite to total protein content and POD activity, during the toxicity test of 28 days especially under concentrations higher than 2.5 mg kg-1. The reduction in neutral red retention (NRR) time along with the increase of dead coelomocytes as the increasing of DnBP concentrations, indicating severe damage to cell viability under varying pollutant stress during cultivation, which could also be proved by comet assay results for exerting evident DNA damage in coelomocytes. DnBP in spiked natural soil could indeed cause damage to tissues, coelomocytes and the nucleus of E. fetida. The key point of the apparent change in different indices presented around 2.5 mg DnBP kg-1 soil, which could be recommended as the threshold of DnBP soil contamination, so that further investigation on threshold values to other soil animals or microorganisms could be discussed.

Subcellular distribution and uptake mechanism of di-n-butyl phthalate in roots of pumpkin (Cucurbita moschata) seedlings

Phthalate acid esters (PAEs) are of particular concern due to their potential environmental risk to human and nonhuman organisms. Although uptake of PAEs by plants has been reported by several researchers, information about the intracellular distribution and uptake mechanisms of PAEs is still lacking. In this study, a series of hydroponic experiments using intact pumpkin (Cucurbita moschata) seedlings was conducted to investigate how di-n-butyl phthalate (DnBP), one of the most frequently identified PAEs in the environment, enters and is distributed in roots. DnBP was transported into subcellular tissues rapidly in the initial uptake period (<12 h). More than 80% of DnBP was detected in the cell walls and organelles, which suggests that DnBP is primarily accumulated in these two fractions due to their high affinity to DnBP. The kinetics of DnBP uptake were fitted well with the Michaelis-Menten equation, suggesting that a carrier-mediated process was involved. The application of 2,4-dinitrophenol and sodium vanadate reduced the uptake of DnBP by 37 and 26%, respectively, while aquaporin inhibitors, silver and glycerol, had no effect on DnBP uptake. These data demonstrated that the uptake of DnBP included a carrier-mediated and energy-dependent process without the participation of aquaporins.

Physiological differences in response to di-n-butyl phthalate (DBP) exposure between low- and high-DBP accumulating cultivars of Chinese flowering cabbage (Brassica parachinensis L.)

To increase understanding on the mechanisms of cultivar difference in contaminant accumulation in crops, this study was designed to compare the physiological responses to di-n-butyl phthalate (DBP) exposure between low (Lvbao70) and high (Huaguan) DBP cultivars of Chinese flowering cabbage (Brassica parachinensis L.). Under high DBP exposure, significant differences in various physiological responses were observed between the two cultivars, which might account for the variation in DBP accumulation. Ultrastructure observation also showed different alterations or damages in the mesophyll cell structures between both cultivars, especially for the chloroplast disintegration, starch grain quantity, and plastoglobuli accumulation. Compared with Huaguan, Lvbao70 suffered greater decreases in biomass, chlorophyll content, carbon assimilation, gas exchange parameters, photosynthetic electron transport capacity, and antioxidase activities, which would have resulted in a great reduction of photosynthetic capacity. Although Lvbao70 enhanced energy dissipation and activities of some antioxidant enzymes, they did not provide sufficient protection against oxidative damage caused by DBP. The result suggested that the lower DBP tolerance of Lvbao70 might be associated with its poor physiological performances, which was responsible for its lower DBP accumulation to protect itself from toxicity. Additionally, Lvbao70 had a significantly lower transpiration rate and stomatal conductance than Huaguan, which might be the factors regulating DBP-accumulation variation.

Occurrence and risk assessment of phthalate esters (PAEs) in vegetables and soils of suburban plastic film greenhouses

Phthalate esters (PAEs) are suspected of having adverse effects on human health and have been frequently detected in soils and vegetables. The present study investigated their occurrence and composition in plastic film greenhouse soil-vegetable systems and assessed their potential health risks to farmers exposed to these widespread pollutants. Six priority control phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DnBP), butyl benzyl phthalate (BBP), di-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP), were determined in 44 plastic film greenhouse vegetables and corresponding soils. Total PAEs ranged from 0.51 to 7.16mgkg(-1) in vegetables and 0.40 to 6.20mgkg(-1) in soils with average concentrations of 2.56 and 2.23mgkg(-1), respectively. DnBP, DEHP and DnOP contributed more than 90% of the total PAEs in both vegetables and soils but the proportions of DnBP and DnOP in vegetables were significantly (p<0.05) higher than in soils. The average concentrations of PAEs in pot herb mustard, celery and lettuce were >3.00mgkg(-1) but were <2.50mgkg(-1) in the corresponding soils. Stem and leaf vegetables accumulated more PAEs. There were no clear relationships between vegetable and soil PAEs. Risk assessment indicates that DnBP, DEHP and DnOP exhibited elevated non-cancer risk with values of 0.039, 0.338 and 0.038, respectively. The carcinogenic risk of DEHP was about 3.94×10(-5) to farmers working in plastic film greenhouses. Health risks were mainly by exposure through vegetable consumption and soil ingestion.

Effect of di-n-butyl phthalate on root physiology and rhizosphere microbial community of cucumber seedlings

The authors investigated the effects of di-n-butyl phthalate (DBP) on root physiology and rhizosphere microbial communities of cucumber seedlings (sativus L. cv Jinyan No. 4). Root protein content and root activity were observed to decrease. From the ultrastructural micrographs, visible impact on the mitochondria, endoplasmic reticulum and vacuole were detected. Moreover, the number of starch grains increased, and some were adhered to other cell components which might be the most direct evidence of DBP causing cellular damage. Results of PCR-DGGE (denaturing gradient gel electrophoresis) indicated that DBP significantly changed the abundance, structure and composition of rhizosphere bacteria when the concentration was higher than 50 mg L(-1). The relative abundances of Firmicutes increased while that of Bacteroidetes decreased. Bacillus was detected as the dominant bacteria in DBP contaminated cucumber rhizospheric soil. The amount of Actinobacteridae and Pseudomonas decreased until it disappeared in the rhizosphere soil when exposed to DBP concentrations higher than 50 mg L(-1).

The influence of facility agriculture production on phthalate esters distribution in black soils of northeast China

The current study investigates the existence of 15 phthalate esters (PAEs) in surface soils (27 samples) collected from 9 different facility agriculture sites in the black soil region of northeast China, during the process of agricultural production (comprising only three seasons spring, summer and autumn). Concentrations of the 15 PAEs detected significantly varied from spring to autumn and their values ranged from 1.37 to 4.90 mg/kg-dw, with a median value of 2.83 mg/kg-dw. The highest concentration of the 15 PAEs (4.90 mg/kg-dw) was determined in summer when mulching film was used in the greenhouses. Probably an increase in environmental temperature was a major reason for PAE transfer from the mulching film into the soil and coupled with the increased usage of chemical fertilizers in greenhouses. Results showed that of the 15 PAEs, di(2-ethylhexyl) phthalate(DEHP), di-n-butyl phthalate (DBP), diethyl phthalate (DEP) and dimethyl phthalate (DMP) were in abundance with the mean value of 1.12 ± 0.22, 0.46 ± 0.05, 0.36 ± 0.04, and 0.17 ± 0.01 mg/kg-dw, respectively; and their average contributions in spring, summer, and autumn ranged between 64.08 and 90.51% among the 15 PAEs. The results of Principal Component Analysis (PCA) indicated the concentration of these four main PAEs significantly differed among the facility agricultures investigated, during the process of agricultural production. In comparison with foreign and domestic results of previous researches, it is proved that the black soils of facility agriculture in northeast China show higher pollution situation comparing with non-facility agriculture soils.

Adsorption of diethyl phthalate ester to clay minerals

Phthalate esters are a group of plasticizers, which have been widely detected in China's agricultural and industrial soils. In this study, batch adsorption experiments were conducted to investigate the environmental effects on the adsorption of diethyl phthalate ester (DEP) to clay minerals. The results showed that DEP adsorption isotherms were well fitted with the Freundlich model; the interlayer spacing of K(+) saturated montmorillonite (K-mont) was the most important adsorption area for DEP, and di-n-butyl ester (DnBP) was limited to intercalate into the interlayer of K-mont due to the bigger molecular size; there was no significant effect of pH and ionic strength on DEP adsorption to K-mont/Ca-mont, but to Na-mont clay. The adsorption to kaolinite was very limited. Data of X-ray diffraction and FTIR spectra further proved that DEP molecules could intercalate into K-/Ca-mont interlayer, and might interact with clay through H-bonding between carbonyl groups and clay adsorbed water. Coated humic acid on clay surface would enhance DEP adsorption at low concentration, but not at high concentration (eg. Ce>0.26 mM). The calculated adsorption enthalpy (ΔHobs) and adsorption isotherms at varied temperatures showed that DEP could be adsorbed easier as more adsorbed. This study implied that clay type, compound structure, exchangeable cation, soil organic matter and temperature played important roles in phthalate ester's transport in soil.

Effects of phthalate ester treatment on seed germination and antioxidant enzyme activities of Phaseolus radiatus L

Effects of di-(2-ethylhexyl) phthalate and di-n-butyl phthalate on seed germination rate and antioxidant enzymes activities of mung bean (Phaseolus radiatus L.) were investigated. Results showed that under the treatment with 10 mg/kg of phthalate esters (PAEs), superoxide dismutase (SOD), peroxidase and catalase (CAT) activities were higher than those of the control (p > 0.05). But SOD and CAT activities decreased with the PAEs concentrations and the treatment duration, and were significantly lower than those of the control (p < 0.05). Effect of PAEs stress on SOD activity in germinating seeds of mung bean displayed a significant dose-effect relationship.

Plant uptake and enhanced dissipation of di(2-ethylhexyl) phthalate (DEHP) in spiked soils by different plant species

This study was conducted to investigate the uptake, accumulation and the enhanced dissipation of di(2-ethylhexyl) phthalate (DEHP) spiked in soil (with a concentration of 117.4 +/- 5.2 mg kg(-1)) by eleven plants including eight maize (Zea mays) cultivars and three forage species (alfalfa, ryegrass and teosinte). The results showed that, after 40 days of treatment, the removal rates of DEHP ranged from 66.8% (for the control) to 87.5% (for the maize cultivar of Huanong-1). Higher removal rate was observed during the first 10 days than the following days. Plants enhanced significantly the dissipation of DEHP in soil. Enhanced dissipation amount in planted soil was 13.3-122 mg pot(-1) for DEHP, and a net removal of 2.2%-20.7% of the initial DEHP was obtained compared with non-plant soil. The contribution of plant uptake to the total enhanced dissipation was < 0.3%, and the enhanced dissipation of soil DEHP might be derived from plant-promoted biodegradation and sorption stronger to the soil. Nevertheless, the capability in accumulation and enhanced dissipation of DEHP from spiked soils varied within different species and cultivars.

Di 2-ethylhexylphtalate in the aquatic and terrestrial environment: a critical review

Phthalates are being increasingly used as softeners-plasticizers to improve the plasticity and the flexibility of materials. Amongst the different plasticizers used, more attention is paid to di (2-ethylhexylphtalate) (DEHP), one of the most representative compounds as it exhibits predominant effects on environment and human health. Meanwhile, several questions related to its sources; toxicity, distribution and fate still remain unanswered. Most of the evidence until date suggests that DEHP is an omnipresent compound found in different ecological compartments and its higher hydrophobicity and low volatility have resulted in significant adsorption to solids matrix. In fact, there are important issues to be addressed with regard to the toxicity of this compound in both animals and humans, its behavior in different ecological systems, and the transformation products generated during different biological or advanced chemical treatments. This article presents detailed review of existing treatment schemes, research gaps and future trends related to DEHP.

Soil contamination by phthalate esters in Chinese intensive vegetable production systems with different modes of use of plastic film

The concentrations of six priority phthalic acid esters (PAEs) in intensively managed suburban vegetable soils in Nanjing, east China, were analyzed using gas chromatography-mass spectrometry (GC-MS). The total PAE concentrations in the soils ranged widely from 0.15 to 9.68 mg kg(-1) with a median value of 1.70 mg kg(-1), and di-n-butyl phthalate (DnBP), bis-(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) were the most abundant phthalate esters. Soil PAE concentrations depended on the mode of use of plastic film in which PAEs were incorporated as plasticizing agents and both the plastic film and poultry manure appeared to be important sources of soil PAEs. Vegetables in rotation with flooded rice led to lower concentrations of PAEs in soil. The results indicate that agricultural plastic film can be an important source of soil PAE contamination and further research is required to fully elucidate the mechanisms of PAE contamination of intensive agricultural soils with different use modes of use of plastic film.

Are medicinal plants polluted with phthalates?

Phthalic acid esters (PAEs) have been employed in polymer materials as a plasticizer to form them more flexible, adhesive, and soluble. These compounds are mainly used in paints, varnishes, personal cares, cosmetics, paper coatings, and adhesives even in bottled waters, shampoo, body deodorant, hairspray, and gels. Phthalates are able to possess remarkable toxic variations depending on their structures. So far, Di-(2-EthylHexyl) Phthalate DEHP and Di-n- Butyl Phthalate DBP have been found to cause reproductive and developmental toxicities. The U.S. Environmental Protection Agency (EPA) classified DEHP as probable human carcinogen. To the best of our knowledge, phthalates showed diverse toxicity profiles according to their structures in the liver, kidneys, thyroid, and testes, which are involved in general toxicity. Furthermore, they are introduced as hormonally-active agents, because they can interfere with the endocrine system in human. Incidence of developmental abnormalities (like skeletal malformations and cleft palate, and undescended testes, lowering testes weight and anogenital distance) seems increasing via high exposure to phthalate metabolites. Although, increasing the capacity for phthalate free plasticizer productions is the first step to restrict the distribution of these toxic manmade compounds, finding the new ways for phthalate absorption from the soil in agricultural fields may have benefits. Also, evaluation and examination of diverse sources of medicinal and food plants to determine the level of phthalate accumulation in their organs are extremely recommended to avoid creating toxicity particularly in reproductive systems.

Diversities of phthalate esters in suburban agricultural soils and wasteland soil appeared with urbanization in China

The distribution of six priority phthalic acid esters (PAEs) in suburban farmland, vegetable, orchard and wasteland soils of Tianjin were obtained with gas chromatography-mass spectrometer analysis in 2009. Results showed that total PAEs varied from 0.05 to 10.4 μg g(-1), with the median value as 0.32 μg g(-1). Di-(2-ethylhexyl) phthalate and di-n-butyl phthalate are most abundant species. PAEs concentrations for the four types of soils exhibited decreasing order as vegetable soil > wasteland soil > farmland soil > orchard soil. PAEs exhibited elevated levels in more developed regions when compared with other studies. The agricultural plastic film could elevate the PAEs contents in soils. Principal component analysis indicated the emission from cosmetics and personal care products and plasticizers were important sources for PAEs in suburban soils in Tianjin. The higher PAEs contents in wasteland soils from suburban area should be paid more attention owing to large amounts of solid wastes appeared with the ongoing urbanization.

Uptake of di-(2-ethylhexyl) phthalate of vegetables from plastic film greenhouses

Uptake of di-(2-ethylhexyl) phthalate (DEHP) of nine vegetables including potherb mustard, bok choy, celery, spinach, cabbage, leaf of tube, lettuce, garlic, and edible amaranth in plastic film greenhouses with different plastic films, film thickness, greenhouse age, and greenhouse height was studied. The results showed that the higher the DEHP content of film, the thicker the film, the lower the height of the greenhouse, and the younger the age of the greenhouse were, the higher the DEHP concentration of vegetables was. The results afford significant information for production of safe vegetables with low level DEHP contamination.