Phthalates (phthalic acid esters) have been widely applied as plasticizers. They are ubiquitous contaminants in soils, thereby posing a threat to human health. In this study, ecotoxicological effects ...of three typical PAEs (dimethyl phthalate-DMP, di-n-octyl phthalate-DOP and butyl benzyl phthalate-BBP) were investigated. As a biological indicator, earthworms (Eisenia fetida) were exposed to phthalates at various doses (0, 0.1, 1, 10 and 50 mg/kg) for different times (7, 14, 21, and 28 d). We evaluated the effects of phthalates on reactive oxygen species (ROS) generation, antioxidant enzymes (superoxide dismutase-SOD, peroxidase-POD and catalase-CAT) activities, glutathione S-transferase enzyme (GST) activity, malondialdehyde (MDA) content and DNA damage. Results showed that ROS content increased with increasing phthalates, whereas ROS content generally increased and then decreased with exposure time. However, antioxidant enzymes activities in earthworms displayed different trends. The GST activity in high-dose treatment group was significantly activated. For DMP and DOP, lipid peroxidation mainly occurred between 14 and 28 d, while for BBP, it primarily existed after 7 d and then disappeared after 28 d. Besides, comet assay indicated that there was a dose-response relationship between the DNA damage and phthalate dose, following DMP > DOP > BBP. Given their toxicity, it is important to understand the mechanisms associated with their eco-toxicity and to reduce their adverse impacts on the environment.
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•Phthalates induced oxidative stress and DNA damage in earthworms.•Phthalates enhanced ROS generation and lipid peroxidation, and activated GST.•Different antioxidant enzymes responded differently to DMP, DOP and BBP.•Phthalate-generated DNA damage followed DMP > DOP > BBP.
Heavy metals pollution of soil and widespread application of neonicotinoid insecticides have caused environmental problems worldwide. To evaluate ecological toxicity resulting from the combined ...pollution of neonicotinoids and heavy metals, typical representatives of neonicotinoid insecticides (imidacloprid, thiamethoxam, dinotefuran) and heavy metals (cadmium, copper, zinc) were selected as soil pollutants; earthworms were used as test organisms. Analysis of the main and interaction effects of a combined pollution process were performed using a uniform design method. Results showed that the reactive oxygen species (ROS) content of earthworms in most treatment groups was higher during exposure than that of the control group. The malondialdehyde (MDA) and ROS content of earthworms demonstrated relatively low values on the 21st day and increased by the 28th day. The interaction between dinotefuran and Cd had significant antagonistic effects on ROS and MDA. The combined pollution adversely affected both the growth and genes of earthworms and also caused damage to the epidermis, midgut, and DNA. The interaction between imidacloprid and Cd was synergistic to ROS, weight inhibition rate, and Olive tail moment (OTM), but was antagonistic to MDA. Of all the single and combined exposures, Zn as a single chemical affected ROS and DNA damage the most, and MDA was significantly enhanced by imidacloprid. Composite pollutants may create different primary effects and interactions causing potential harm to soil organisms.
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•Combined pollution caused oxidative stress and damage to the growth, tissue, and DNA in earthworms.•Analysis of the main and interaction effects of a combined pollution process were performed using a uniform design method.•ROS, MDA, weight inhibition rate, and OTM of earthworms were all affected by the interaction between imidacloprid and Cd.•Excessive ROS and MDA likely caused damage to the epidermis, midgut, and DNA of earthworms.
Livestock manure is a major reservoir of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). This study investigated the distribution characteristics of ARB, ARGs in fresh and ...composted manures of traditional breading industry in rural areas in China. Samples collected were naturally piled without professional composting, and will be applied to farmland. The real-time quantitative polymerase chain reaction (qPCR) results showed the presence of ten target ARGs and two mobile genetic elements (MGEs) in the tested manure samples. The relative abundance of tetracycline and sulfonamide resistance genes (TRGs and SRGs) was generally higher than that of macrolide resistance genes (MRGs), followed by quinolone resistance genes (QRGs). There were significant positive correlations between the abundance of sul1, sul2, tetW and MGEs (intl1, intl2). In addition, the distribution of target ARGs was associated with the residual concentrations of doxycycline (DOX), sulfamethazine (SM2), enrofloxacin (ENR) and tylosin (TYL). Overall, a total of 24 bacterial genera were identified. The resistance rates of ARB were 17.79%–83.70% for SM2, followed 0.40%–63.77% for TYL, 0.36%–43.90% for DOX and 0.00%–13.36% for ENR, which showed a significant dose-effect. This study also demonstrated that the abundance of clinically relevant ARB and ARGs in chicken, swine and cow fresh manures significantly greater than that in composted manures, and chicken and swine manures had higher proportion of ARB and higher abundance of ARGs than that in cow manures.
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•Chicken and swine manures have higher abundance of ARB and ARGs than cow manures.•The abundance of ARB and ARGs in fresh manures was significantly higher than that in composted manures.•Detected antibiotics and MGEs were significantly correlated with some of the target ARGs.•Acinetobacter lwoffii and Psychrobacter pulmonis are multiple resistant bacteria.
The aim of the present study was to assess the toxic effects of pyraclostrobin on DNA damage and antioxidant enzymatic activities in the zebrafish (Danio rerio) liver. Based on the 96-h median lethal ...concentration (96 h LC50, 0.056 mg/L) of this chemical, fish were exposed to three doses (0.001, 0.01, and 0.02 mg/L) and sampled on days 7, 14, 21 and 28 after the initiation of a subchronic toxicity test. The levels of superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), glutathione S-transferase (GST), reactive oxygen species (ROS) and DNA damage were determined. The amount of pyraclostrobin residue in the water was also measured. The concentrations in the three treatment groups varied no more than 5% during the exposure periods, indicating that pyraclostrobin is relatively stable during this time in an aquatic environment. ROS and MDA levels significantly changed in a dose dependent manner during the experiment. Enzymatic activities were inhibited to a certain extent. DNA damage was significantly enhanced. These results collectively indicate that pyraclostrobin induces oxidative stress and DNA damage in zebrafish.
•Acute and subchronic toxic effects of pyraclostrobin on zebrafish were investigated.•Pyraclostrobin can cause oxidative stress and oxidative damage in zebrafish.•The comet assay was the most sensitive of all biomarkers used in the present study.•The doses of pyraclostrobin are at a relatively stable level in the present study.
Chlorpyrifos, a broad−spectrum organophosphorus insecticide, has been widely detected worldwide and is a potential neurotoxin and endocrine disruptor. Besides, chlorpyrifos has been proven that have ...a negative effect on soil microbes. In the present study, chlorpyrifos formulation (LORSBAN®, 45% emulsifiable concentrate) was applied in an agricultural field at the recommended dose (R dose, 270.0 and 337.5 g a.i. ha−1 for wheat and maize respectively) and double recommended (DR) dose. Chlorpyrifos residue level and effect on soil microbes related to soil carbon and nitrogen cycle function were analyzed. Results showed that the half−lives of chlorpyrifos in wheat and maize field soil were 7.23–8.23 and 1.45–1.77 d, respectively. Application of chlorpyrifos at even DR dose did not result in unacceptable residual chlorpyrifos, where the final residual chlorpyrifos in wheat/maize (leaf, stem, and grain) was meet the requirement of the maximum residual limit (0.5 mg kg−1 for wheat and 0.05 mg kg−1 for maize) in China. Chlorpyrifos enhanced the activity of β−glucosidase by increasing the relative abundance of Sphingosinicella and promoted the carbon cycle in wheat field. The changes of cbbLR and cbbLG gene abundance also confirmed that chlorpyrifos could affect the import and export of soil carbon pool. The effect of chlorpyrifos on soil N cycle was determined by changes in the abundance of the bacterial genus Gemmatimonas, which is associated with denitrification. Further analysis of N−cycle functional genes and urease activity showed that chlorpyrifos inhibited nitrogen fixation in wheat field, but promoted nitrogen fixation in maize field. In general, bacterial abundance, urease, and AOA−amoA gene could be early warning markers of chlorpyrifos contamination. The results demonstrated the negative effects of chlorpyrifos on soil microbes especially on soil C and N cycle in actual agricultural field. It provides new insights about chlorpyrifos environmental pollution and its effect on soil ecosystems.
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•Final residual chlorpyrifos in wheat or maize was below the maximum residue limit.•Chlorpyrifos formulation have negative effect on soil bacteria abundance.•Effect of chlorpyrifos on soil N cycle was related the genus Gemmatimonas.•Chlorpyrifos could affect the import and export of soil carbon pool.
Graphene–chitosan composite film modified glassy carbon electrode was prepared and characterized. The fabricated electrode showed excellent electrochemical catalytic activities towards the oxidation ...of catechol (CT), resorcinol (RS) and hydroquinone (HQ). The oxidation overpotentials of CT, RS and HQ decreased significantly and the corresponding oxidation currents increased remarkably compared with those obtained at the bare GCE and chitosan modified GCE. Some kinetic parameters, such as the electron transfer number (
n), proton transfer number (
m), charge transfer coefficient (
α) and the apparent heterogeneous electron transfer rate constant (
k
s), were calculated. Differential pulse voltammetry was used for the simultaneous determination of CT, RS and HQ in their ternary mixture. The peak-to-peak potential separations between CT and RS, RS and HQ, and HQ and CT were 0.388, 0.484 and 0.096
V, respectively. The calibration curves for CT, RS and HQ were obtained in the range of 1
×
10
−6 to 4
×
10
−4, 1
×
10
−6 to 5.5
×
10
−4 and 1
×
10
−6 to 3
×
10
−4
mol
L
−1, respectively. The detection limits were 7.5
×
10
−7
mol
L
−1 (
S/
N
=
3).
Azoxystrobin is a frequently used fungicide in agriculture. Its toxicological effects on non-target organisms have aroused attention. In the present work, the toxic effects of azoxystrobin on ...zebrafish (Danio rerio) were investigated. Male and female zebrafish were separately exposed to a control solution and three azoxystrobin treatments (1, 10, and 100μg/L) and were sampled on days 7, 14, 21, and 28. Reactive oxygen species (ROS) were accumulated in excess in the zebrafish livers. Superoxide dismutase (SOD) activity was significantly inhibited in the male zebrafish. Moreover, a notable decrease was also observed after day 21 in the female zebrafish. Catalase (CAT) activity was induced by the azoxystrobin treatments with the exception of the 1μg/L treatment. A significant increase in glutathione-S-transferase (GST) activity was observed after day 21. Lipid peroxidation (LPO) was generated, and DNA damage was enhanced in a concentration-dependent manner. In conclusion, azoxystrobin induced oxidative stress and genotoxicity in zebrafish livers.
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•Azoxystrobin induced oxidative stress and genotoxicity in zebrafish livers.•ROS was generated in excess.•SOD was inhibited, CAT and GST were stimulated at most azoxystrobin treatments.•Lipid peroxidation increased as a consequence of oxidative stress.•The excess ROS was one of the causes for the DNA damage.
The graphene–chitosan composite film modified glassy carbon electrode (GCE) was fabricated and used to determine 4-aminophenol (4-AP). In 0.1
M pH 6.3 phosphate buffer solution, the redox peak ...currents of 4-AP increased significantly and the peak-to-peak separation decreased greatly at graphene–chitosan composite film modified GCE compared with bare GCE and chitosan modified GCE, indicating that graphene possessed electrocatalytic activity towards 4-AP. The experimental conditions were optimized and the kinetic parameters were investigated. The oxidation mechanism was discussed. Under the optimal experimental conditions, the oxidation peak current was proportional to 4-AP concentration in the range from 0.2 to 550
μM with the correlation coefficient of 0.9930. The detection limit was 0.057
μM (S/N
=
3). Using the proposed method, 4-AP was successfully determined in water samples and paracetamol tablets with standard addition method, suggesting that this method can be applied to determine 4-AP in environments and pharmaceuticals.
Azoxystrobin has been widely used in recent years. The present study investigated the oxidative stress and DNA damage effects of azoxystrobin on earthworms (Eisenia fetida). Earthworms were exposed ...to different azoxystrobin concentrations in an artificial soil (0, 0.1, 1, and 10mg/kg) and sampled on days 7, 14, 21, and 28. Superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), glutathione-S-transferase (GST), reactive oxygen species (ROS), and malondialdehyde (MDA) content were measured by an ultraviolet spectrophotometer to determine the antioxidant responses and lipid peroxidation. Single cell gel electrophoresis (SCGE) was used to detect DNA damage in the coelomocytes. Compared with these in the controls, earthworms exposed to azoxystrobin had excess ROS accumulation and greater SOD, POD, and GST activity while the opposite trend occurred for CAT activity. MDA content increased after 14-day exposure, and DNA damage was enhanced with an increase in the concentration of azoxystrobin. In conclusion, azoxystrobin caused oxidative stress leading to lipid peroxidation and DNA damage in earthworms.
•Azoxystrobin induced oxidative stress and DNA damage in Eisenia fetida.•SOD, POD and GST were all stimulated by azoxystrobin, as opposed to CAT.•Azoxystrobin caused ROS accumulation and lipid peroxidation.•DNA damage increased with increasing azoxystrobin concentration and exposure time.
In this study, eighteen 3.30-m-long sediment profiles were sampled in Maozhou River. In order to investigate the sediment pollution status and potential sources of heavy metals, we performed heavy ...metal contents, grain size, organic matter concentration, moisture concentration and total phosphorus analysis, and assessed the ecological risk of heavy metal pollution in the study area using enrichment coefficient, geo-accumulation index and potential ecological risk index. The results indicated that the heavy metal concentrations in the Maozhou River sediments were 3.73–417 times higher than the soil background in Guangdong Province and the average concentrations were 0.447–15.1 times higher than Chinese lacustrine sediments. The Cr, Ni, Cu, Zn, Cd and Pb contents were significantly correlated with each other (
p
< 0.01), indicating similar deposition process. In addition, spatial and vertical distribution of heavy metals showed similar variation patterns and extreme high contents are distributed in the interchange area. The ecological risk of Maozhou River was much higher than other river sediments in Guangdong Province, especially for Cu, Cd and Ni. The variation pattern of potential ecological risk index is similar with that of heavy metals and the assessment results indicated high ecological risk in the Maozhou River sediments, which is in good agreement with the EF and I
geo
results. This study would provide some references for the treatment of heavy metals’ pollution in Maozhou River.
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