Effect of phenanthrene on the biological characteristics of earthworm casts and their relationships with digestive and anti-oxidative systems.

Earthworms as ecosystem engineers partially improve soil properties by egesting casts. Our previous study confirmed that soil pollution affects the physico-chemical properties of earthworm casts. It is still unclear whether the biological properties (e.g. cellulase, urease, and acid and alkaline phosphatase activities, as well as microbial biomass carbon) of casts are affected by foreign substances in soil. The present study aimed to investigate the effect of phenanthrene (PHE) on the biological characteristics of earthworm (Eisenia fetida) casts. Furthermore, correlations between cast properties and the digestive and antioxidant systems were explored by the determination of digestive enzyme (urease, protease, acid and alkaline phosphatase) activities, antioxidant indexes [superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)], as well as malondialdehyde (MDA) content. Exposure at a range of PHE doses (0, 2, 5, 10, and 20 mg kg-1) for 15 d resulted in the following observations: (1) Compared with urease, as well as acid and alkaline phosphatase activities, cellulase activities in both soil and casts were sensitive to PHE, and could potentially act as biomarkers to provide early-warning signals for soil pollution. (2) Microbial biomass carbon in casts was modified, but with no clear pattern. (3) Cellulase and POD activities, as well as MDA content in earthworms, increased with elevated exposure to PHE in soil. Protease, SOD, and CAT activities exhibited a biphasic dose response to PHE, while acid and alkaline phosphatase activities were inhibited under treatment conditions. (4) Correlation analysis suggested that microbial biomass carbon in casts significantly and positively correlated with cellulase and acid phosphatase activities of earthworms, but negatively correlated with protease activities. A significant but weak negative correlation between alkaline phosphatase activities in casts and POD activities was also observed. Based on these results, we concluded that PHE content in soil modified some biological properties of casts, by partially affecting the earthworm's digestive and antioxidant systems. This study advances our knowledge of earthworm ecology in polluted soil by providing a better understanding of their ecological functions.

Effects of Lonicera japonica extract on performance, blood biomarkers of inflammation and oxidative stress during perinatal period in dairy cows.

OBJECTIVE: An experiment was conducted to evaluate the effects of Lonicera japonica extract (LJE) on milk production, rumen fermentation and blood biomarkers of energy metabolism, inflammation and oxidative stress during the perinatal period of Holstein dairy cows. METHODS: Eighteen Holstein dairy cows were used in a complete randomized design experiment with 3 dietary treatments and 6 cows per treatment. All cows received the same basal total mixed ration (TMR) including a prepartal diet (1.35 Mcal of net energy for lactation [NEL]/kg of dry matter [DM], 13.23% crude protein [CP]) from -60 d to calving and a postpartal diet (1.61 Mcal of NEL/kg of DM, 17.39% CP) from calving to 30 days in milk (DIM). The 3 dietary treatments were TMR supplemented with LJE at 0 (control), 1 and 2 g/kg DM, respectively. LJE was offered from 21 d before calving to 30 DIM. Dry matter intake (DMI) and milk production were measured daily after calving. Milk and rumen fluid samples were collected on 29 and 30 d after calving. On -10, 4, 14, and 30 d relative to calving, blood samples were collected to analyze the biomarkers of energy metabolism, inflammation and oxidative stress. RESULTS: Compared with control diet, LJE supplementation at 1 and 2 g/kg DM increased DMI, milk yield and reduced milk somatic cell count. LJE supplementation also decreased the concentrations of blood biomarkers of pro-inflammation (interleukin-1ß [IL-1ß], IL-6, and haptoglobin), energy metabolism (nonesterified fatty acid and ß-hydroxybutyric acid) and oxidative stress (reactive oxygen metabolites), meanwhile increased the total antioxidant capacity and superoxide dismutase concentrations in blood. No differences were observed in rumen pH, volatile fatty acid, and ammonia-N (NH3-N) concentrations between LJE supplemented diets and the control diet. CONCLUSION: Supplementation with 1 and 2 g LJE/kg DM could increase DMI, improve lactation performance, and enhance anti-inflammatory and antioxidant capacities of dairy cows during perinatal period.

Effect of phenanthrene on the physicochemical properties of earthworm casts in soil.

Earthworms have been widely studied as bioindicators of soil health for their important role in sustaining soil structure and functions. Many soil contaminants such as phenanthrene have been confirmed to exert adverse effects on earthworms' growth, reproduction, behaviors and biochemical conditions. However, their effects on the properties of earthworm casts have been little studied. In the present study, the effect of different doses of phenanthrene (PHE) (0, 2, 5, 10, 20 mg/kg) on the six physicochemical properties and Fourier transform infrared spectroscopy (FTIR) spectra characteristics of earthworm casts was assessed in artificial soil in a laboratory. 1) Residual concentration of PHE in soils and casts increased with the increasing exposure concentrations and followed the order of casts > soil, concluding that Kow values are the important factor affecting the distribution of hydrophobic organic contaminants (HOCs) in soil and casts; 2) Earthworms produced casts with improved total organic carbon (TOC) (15-19%), NH4+-N (550-800%), total available phosphorus (TAP) (300-450%), cation exchange capacity (CEC) (about 15%) and available potassium (AK) (7-12.6%) compared to that in unpolluted soil, indicating that earthworms still have the ability to play the role of ecological engineers even in polluted soil; 3) The sensitivity of different properties of casts to phenanthrene varies, the order of sensitivity being (most sensitive first) NH4+-N ( triggered as 2 mg/kg of exposure concentrations) > AK (5 mg/kg) > Olsen-P (10 mg/kg) > TOC = pH= CEC (no response within the range of exposure concentrations). NH4+-N content in casts shows a clear dose-response relationship when the exposure exceeds 2 mg/kg, indicating that the index might be a potential sensitive biomarker to provide early warning for soil pollution. 4) FTIR spectra showed that the constitution of casts from earthworms in PHE-spiked soil was not significantly alternated. However, FTIR spectra revealed that the concentrations of C-O of polysaccharide in casts increased with the elevated exposure concentrations, indicating that intensities of C-O of polysaccharide at 1032 cm-1 of casts might be also a potential biomarker for the early-warning of soil pollution. This study advances the knowledge of earthworm ecology in polluted soil, and further extends the scope of earthworm casts as a potential biomarker in soil pollution assessment.

Microbial defluorination of TFA, PFOA, and HFPO-DA by a native microbial consortium under anoxic conditions.

In this study, the biodegradability of trifluoroacetate (TFA), perfluorooctanoic acid (PFOA), and perfluoro-2-methyl-3-oxahexanoic acid (HFPO-DA) by a native microbial community was evaluated over a 10-month incubation period. The observed microbial defluorination ratios and removal efficiency were 3.46 ( ± 2.73) % and 8.03 ( ± 3.03) %, 8.44 ( ± 1.88) % and 13.52 ( ± 4.96) %, 3.02 ( ± 0.62) % and 5.45 ( ± 2.99) % for TFA, PFOA and HFPO-DA, respectively. The biodegradation intermediate products, TFA and pentafluoropropionic acid (PFA), of PFOA and HFPO-DA were detected in their biodegradation treatment groups. Furthermore, the concentrations of the PFOA metabolites, perfluorohexanoic acid (PFHxA) and perfluoroheptanoic acid (PFHpA), in the aqueous solutions after incubation were quantified to be 0.21 and 4.14 µg/L. TFA, PFOA and HFPO-DA significantly reduced the microbial diversity and changed the structure of the community. The co-occurrence network analysis showed that low abundance species, such as Flexilinea flocculi, Bacteriovorax stolpii, and g_Sphingomonas, are positively correlated with the generation of fluoride ion, implying their potential collaborative functions contributing to the observed biodefluorination. The findings in this study can provide insights for the biodegradation of perfluoroalkyl carboxylic acids and their emerging alternatives by indigenous microorganisms in the environment.

Effects of short and long-term thermal exposure on microbial compositions in soils contaminated with mixed benzene and benzo[a]pyrene: A short communication.

Polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylene (BTEX) are the most persistent and toxic organic contaminants often found co-contaminated in anthropogenic and petrochemical industrial sites. Therefore, an experiment was performed for the safe biodegradation of benzene and benzo[a]pyrene (BaP) through thermally-enhanced biodegradation, and to explore the influence of elevated thermal treatments on microbial diversity and composition. The results revealed that elevated thermal treatments (15 to 45 °C) significantly enhanced the diversity of both bacteria and fungi. The composition analysis revealed that short-term and long-term elevated temperature conditions can directly enhance the specificity of microorganisms that play a crucial role in the biodegradation of benzene and BaP co-contaminated soil. Moreover, the indirect role of elevated temperature conditions on microbial compositions was through the fluctuations of soil properties, especially soil pH, moisture, TOC, potassium, phosphorous, total Fe, Fe(II), and Fe(III). In addition, the correlation analyses revealed that thermal exposure enhances the synergistic association (fungal-fungal, fungal-bacterial, bacterial-bacterial) of microbes to degrade the toxic contaminants and to cope with harsh environmental conditions. These results concluded that the biodegradation of benzene and BaP co-contamination was efficiently enhanced under the thermally-enhanced biodegradation approach and the elevation of temperature can affect the microbial compositions directly via microbial specificity or indirectly by influencing the soil properties.

Understanding microplastic presence in different wastewater treatment processes: Removal efficiency and source identification.

Municipal effluents discharged from wastewater treatment plants (WWTPs) are a considerable source of microplastics in the environment. The dynamic profiles of microplastics in treatment units in WWTPs with different treatment processes remain unclear. This study quantitatively analyzed microplastics in wastewater samples collected from different treatment units in two tertiary treatment plants with distinct processes. The influents contained an average of 15.5 ± 3.5 particles/L and 38.5 ± 2.5 particles/L in the two WWTPs with in the oxidation ditch process and the integrated fixed-film activated sludge process, respectively. Interestingly, microplastic concentrations in the influent were more influenced by the population density in the served area than sewage volume or served population equivalent. Throughout the treatment process, concentrations were reduced to 1.5 ± 0.5 particles/L and 1.0 ± 1.0 particles/L in the final effluents, representing an overall decrease of 90% and 97%, in WWTPs with the oxidation ditch process and integrated fixed-film activated sludge process, respectively. A significant proportion of the microplastics were removed during the primary treatment stage in both WWTPs, with better performance for foam, film, line-shaped and large-sized microplastics. Most microplastics were accumulated in activated sludge, indicating its key role as the primary sink in WWTPs. The multiple correspondence analysis identified laundry washing and daily necessities such as packaging and containers as the major contributors to microplastics in WWTPs. The study proposed recommendations for upgrading WWTPs, modifying designs, and implementing strategies to reduce microplastic sources, aiming to minimize the release of microplastics into the environment. These findings can shed lights on the sources of microplastics in WWTPs, and advance our understanding of the mechanisms for more effective microplastic removals in wastewater treatment technologies in future applications.

Mechanisms of benzene and benzo[a]pyrene biodegradation in the individually and mixed contaminated soils.

There is a lack of knowledge on the biodegradation mechanisms of benzene and benzo [a]pyrene (BaP), representative compounds of polycyclic aromatic hydrocarbons (PAHs), and benzene, toluene, ethylbenzene, and xylene (BTEX), under individually and mixed contaminated soils. Therefore, a set of microcosm experiments were conducted to explore the influence of benzene and BaP on biodegradation under individual and mixed contaminated condition, and their subsequent influence on native microbial consortium. The results revealed that the total mass loss of benzene was 56.0% under benzene and BaP mixed contamination, which was less than that of individual benzene contamination (78.3%). On the other hand, the mass loss of BaP was slightly boosted to 17.6% under the condition of benzene mixed contamination with BaP from that of individual BaP contamination (14.4%). The significant differences between the microbial and biocide treatments for both benzene and BaP removal demonstrated that microbial degradation played a crucial role in the mass loss for both contaminants. In addition, the microbial analyses revealed that the contamination of benzene played a major role in the fluctuations of microbial compositions under co-contaminated conditions. Rhodococcus, Nocardioides, Gailla, and norank_c_Gitt-GS-136 performed a major role in benzene biodegradation under individual and mixed contaminated conditions while Rhodococcus, Noviherbaspirillum, and Phenylobacterium were highly involved in BaP biodegradation. Moreover, binary benzene and BaP contamination highly reduced the Rhodococcus abundance, indicating the toxic influence of co-contamination on the functional key genus. Enzymatic activities revealed that catalase, lipase, and dehydrogenase activities proliferated while polyphenol oxidase was reduced with contamination compared to the control treatment. These results provided the fundamental information to facilitate the development of more efficient bioremediation strategies, which can be tailored to specific remediation of different contamination scenarios.

Unveiling complete natural reductive dechlorination mechanisms of chlorinated ethenes in groundwater: Insights from functional gene analysis.

Monitored natural attenuation (MNA) of chlorinated ethenes (CEs) has proven to be a cost-effective and environment-friendly approach for groundwater remediation. In this study, the complete dechlorination of CEs with formation of ethene under natural conditions, were observed at two CE-contaminated sites, including a pesticide manufacturing facility (PMF) and a fluorochemical plant (FCP), particularly in the deeply weathered bedrock aquifer at the FCP site. Additionally, a higher abundance of CE-degrading bacteria was identified with heightened dechlorination activities at the PMF site, compared to the FCP site. The reductive dehalogenase genes and Dhc 16 S rRNA gene were prevalent at both sites, even in groundwater where no CE dechlorination was observed. vcrA and bvcA was responsible for the complete dechlorination at the PMF and FCP site, respectively, indicating the distinct contributions of functional microbial species at each site. The correlation analyses suggested that Sediminibacterium has the potential to achieve the complete dechlorination at the FCP site. Moreover, the profiles of CE-degrading bacteria suggested that dechlorination occurred under Fe3+/sulfate-reducing and nitrate-reducing conditions at the PMF and FCP site, respectively. Overall these findings provided multi-lines of evidence on the diverse mechanisms of CE-dechlorination under natural conditions, which can provide valuable guidance for MNA strategies implementation.

A novel sensitive and selective ligation-based ATP assay using a molecular beacon.

In this paper, a novel, facile fluorometric ATP assay with high sensitivity and excellent selectivity has been reported. This approach utilizes a molecular beacon, T4 DNA ligase and two short oligonucleotides. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction and the ligation product restores the fluorescence of the molecular beacon. Owing to the high sensitivity of the molecular beacon and T4 DNA ligase's high substrate dependence, this novel ATP assay demonstrates exceptional selectivity and high sensitivity down to 0.14 nM in homogeneous solution. Cellular ATP concentrations in several cell lines have been determined by measuring the lysate sample containing 8.0 × 10(3) cells.

HSSNet: A End-to-End Network for Detecting Tiny Targets of Apple Leaf Diseases in Complex Backgrounds.

Apple leaf diseases are one of the most important factors that reduce apple quality and yield. The object detection technology based on deep learning can detect diseases in a timely manner and help automate disease control, thereby reducing economic losses. In the natural environment, tiny apple leaf disease targets (a resolution is less than 32 × 32 pixel2) are easily overlooked. To address the problems of complex background interference, difficult detection of tiny targets and biased detection of prediction boxes that exist in standard detectors, in this paper, we constructed a tiny target dataset TTALDD-4 containing four types of diseases, which include Alternaria leaf spot, Frogeye leaf spot, Grey spot and Rust, and proposed the HSSNet detector based on the YOLOv7-tiny benchmark for professional detection of apple leaf disease tiny targets. Firstly, the H-SimAM attention mechanism is proposed to focus on the foreground lesions in the complex background of the image. Secondly, SP-BiFormer Block is proposed to enhance the ability of the model to perceive tiny targets of leaf diseases. Finally, we use the SIOU loss to improve the case of prediction box bias. The experimental results show that HSSNet achieves 85.04% mAP (mean average precision), 67.53% AR (average recall), and 83 FPS (frames per second). Compared with other standard detectors, HSSNet maintains high real-time detection speed with higher detection accuracy. This provides a reference for the automated control of apple leaf diseases.

Mechanisms of biostimulant-enhanced biodegradation of PAHs and BTEX mixed contaminants in soil by native microbial consortium.

Despite the co-occurrence of polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene, and xylene (BTEX) in the field, to date, knowledge on the bioremediation of benzene and benzo[a]pyrene (BaP) mixed contaminants is limited. In this study, the mechanisms underlying the biodegradation of benzene and BaP under individual and co-contaminated conditions followed by the enhanced biodegradation using methanol, ethanol, and vegetable oil as biostimulants were investigated. The results demonstrated that the benzene biodegradation was highly reduced under the co-contaminated condition compared to the individual benzene contamination, whereas the BaP biodegradation was slightly enhanced with the co-contamination of benzene. Moreover, biostimulation significantly improved the biodegradation of both contaminants under co-contaminated conditions. A trend of significant reduction in the bioavailable BaP contents was observed in all biostimulant-enhanced groups, implying that the bioavailable BaP was the preferred biodegradable BaP fraction. Furthermore, the enzymatic activity analysis revealed a significant increase in lipase and dehydrogenase (DHA) activities, as well as a reduction in the catalase and polyphenol oxidase, suggesting that the increased hydrolysis of fats and proton transfer, as well as the reduced oxidative stress, contributed to the enhanced benzene and BaP biodegradation in the vegetable oil treatment. In addition, the microbial composition analysis results demonstrated that the enriched functional genera contributed to the increased biodegradation efficiency, and the functional genera in the microbial consortium responded differently to different biostimulants, and competitive growth was observed in the biostimulant-enhanced treatments. In addition, the enrichment of Pseudomonas and Rhodococcus species was noticed during the biostimulation of benzene and BaP co-contamination soil, and was positively correlated with the DHA enzyme activities, indicating that these species encode DHA genes which contributed to the higher biodegradation. In conclusion, multiple lines of evidence were provided to shed light on the mechanisms of biostimulant-enhanced biodegradation of PAHs and BTEX co-contamination with native microbial consortiums.

A Precise Image-Based Tomato Leaf Disease Detection Approach Using PLPNet.

Tomato leaf diseases have a significant impact on tomato cultivation modernization. Object detection is an important technique for disease prevention since it may collect reliable disease information. Tomato leaf diseases occur in a variety of environments, which can lead to intraclass variability and interclass similarity in the disease. Tomato plants are commonly planted in soil. When a disease occurs near the leaf's edge, the soil backdrop in the image tends to interfere with the infected region. These problems can make tomato detection challenging. In this paper, we propose a precise image-based tomato leaf disease detection approach using PLPNet. First, a perceptual adaptive convolution module is proposed. It can effectively extract the disease's defining characteristics. Second, a location reinforcement attention mechanism is proposed at the neck of the network. It suppresses the interference of the soil backdrop and prevents extraneous information from accessing the network's feature fusion phase. Then, a proximity feature aggregation network with switchable atrous convolution and deconvolution is proposed by combining the mechanisms of secondary observation and feature consistency. The network solves the problem of disease interclass similarities. Finally, the experimental results show that PLPNet achieved 94.5% mean average precision with 50% thresholds (mAP50), 54.4% average recall (AR), and 25.45 frames per second (FPS) on a self-built dataset. The model is more accurate and specific for the detection of tomato leaf diseases than other popular detectors. Our proposed method may effectively improve conventional tomato leaf disease detection and provide modern tomato cultivation management with reference experience.

Thermally enhanced biodegradation of benzo[a]pyrene and benzene co-contaminated soil: Bioavailability and generation of ROS.

In this study, a set of comprehensive experiments were conducted to explore the effects of temperature on the biodegradation, bioavailability, and generation of reactive oxygen species (ROS) by thermally enhanced biodegradation (TEB) under benzene and BaP co-contaminated conditions. The biodegradation rates of benzene increased from 57.4% to 88.7% and 84.9%, and the biodegradation efficiency of BaP was enhanced from 15.8% to 34.6% and 28.6%, when the temperature was raised from the ambient temperature of 15 °C to 45 °C and 30 °C, respectively. In addition, the bioavailability analysis results demonstrated that the water- and butanol-extractable BaP increased with elevated temperatures. High enzymatic activities and PAH-RHDα gene in gram-positive bacteria favored the long-term elevated temperatures (30 and 45 °C) compared to gram-negative bacteria. Moreover, ROS species (O2•- and •OH) generation was detected which were scavenged by the increased superoxide dismutase and catalase activities at elevated temperatures. Soil properties (pH, TOC, moisture, total iron, Fe3+, and Fe2+) were affected by the temperature treatments, revealing that metal-organic-associated reactions occurred during the TEB of benzene-BaP co-contamination. The results concluded that biodegradation of benzene-BaP co-contamination was greatly improved at 45 °C and that microbial activities enhanced the biodegradation under TEB via the increased bioavailability and generation and degradation of ROS.

Thermally enhanced bioremediation: A review of the fundamentals and applications in soil and groundwater remediation.

Thermally enhanced bioremediation (TEB), a new concept proposed in recent years, explores the combination of thermal treatment and bioremediation to address the challenges of the low efficiency and long duration of bioremediation. This study presented a comprehensive review regarding the fundamentals of TEB and its applications in soil and groundwater remediation. The temperature effects on the bioremediation of contaminants were systematically reviewed. The thermal effects on the physical, chemical and biological characteristics of soil, and the corresponding changes of contaminants bioavailability and microbial metabolic activities were summarized. Specifically, the increase in temperature within a suitable range can proliferate enzymes enrichment, extracellular polysaccharides and biosurfactants production, and further enhancing bioremediation. Furthermore, a systematic evaluation of TEB applications by utilizing traditional in situ heating technologies, as well as renewable energy (e.g., stored aquifer thermal energy and solar energy), was provided. Additionally, TEB has been applied as a biological polishing technology post thermal treatment, which can be a cost-effective method to address the contaminants rebounds in groundwater remediation. However, there are still various challenges to be addressed in TEB, and future research perspectives to further improve the basic understanding and applications of TEB for the remediation of contaminated soil and groundwater are presented.

Co-occurrence and correlations of PFASs and chlorinated volatile organic compounds (cVOCs) in subsurface in a fluorochemical industrial park: Laboratory and field investigations.

Fluorochemical industrial park (FIP) represents an important source of per- and polyfluoroalkyl substances (PFASs) and chlorinated volatile organic compounds (cVOCs). Exploring the co-occurrence and correlations of PFASs and cVOCs is a key step towards the understanding their distributions in the field. In this study, perfluorooctanoic acid (PFOA) was the dominant compound in groundwater and aquifer solids, and elevated concentrations of short-chain perfluoroalkyl carboxylic acids (PFCAs) and hexafluoropropylene oxide oligomers were also detected in the field, suggesting their wide applications as substitutes for PFOA. Correlation analyses between PFASs and cVOCs suggested that cVOCs had a significant influence on the distribution and composition of PFASs in the field. In addition, the presence of cVOCs in the form of dense non-aqueous-phase organic liquids (DNAPL) affected the distribution and migration of PFASs at various depths, as evidenced by the relatively high PFASs concentrations (204 µg/L) and PFOA abundance (85.4%) in the deep aquifer, likely due to DNAPL-water interfaces sorption or partition into bulk DNAPL. The log Kd values, determined in the laboratory, were found to increase in the presence of DNAPL, especially for PFOA, with more than one time higher than those of perfluorobutanoic acid (PFBA) and hexafluoropropylene oxide dimer acid (HFPO-DA). This conclusion further demonstrated that PFOA had a higher potential to participate into DNAPL, which can migrate with DNAPL to the deep aquifer, supporting the higher abundance of PFOA in the deep aquifer mentioned above. However, the log Kd-field values of PFBA and HFPO-DA in the field were higher than that of PFOA, and no significant correlations (p > 0.05) were found between log Kd-field values and the chain-length of PFCAs at various depths, suggesting that the phenomena observed in the field are a result of composite influencing factors.

Distribution, source identification and health risk assessment of PFASs in groundwater from Jiangxi Province, China.

There is an urgent need to investigate on the distribution and fate of short-chain analogues and emerging per- and polyfluoroalkyl substances (PFASs) in groundwater, and little research on their source apportionment and health risks through the drinking water exposure pathway has been carried out. In present study, the concentration and source of 22 PFASs, including five alternatives: 6:2 fluorotelomer sulfonate (6:2 FTS), potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (F-53B), hexafluoropropylene oxide trimer acid (HFPO-TA), hexafluoropropylene oxide dimer acid (HFPO-DA) and ammonium 4, 8-dioxa-3H-perfluorononanoate (ADONA), were analyzed in 88 groundwater samples from wells in Jiangxi Province, southeastern China. The total PFASs concentration (Σ18PFASs) in groundwater varied from 1.27 to 381.00 ng/L (mean 47.60 ng/L). Short-chain perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPeA) were the most abundant perfluorinated carboxylic acids (PFCAs), and short-chain perfluorobutanesulfonate (PFBS) was the most abundant perfluorinated sulfonic acids (PFSAs) in groundwater samples. The quantitative source apportionment by nonnegative matrix/tensor factorization coupled with k-means clustering (NMFk) model suggested that short-chain homologues and emerging alternatives have been used as substitutes for legacy PFOS and PFOA. Furthermore, the human risk assessment results showed that the estimated daily intakes (EDIs) for short-chain PFCAs were higher than that of PFOA, whereas the EDIs of PFBS, 6:2 FTS and F-53B were comparable to that of PFOS.

Bioremediation of PAHs and heavy metals co-contaminated soils: Challenges and enhancement strategies.

Systemic studies on the bioremediation of co-contaminated PAHs and heavy metals are lacking, and this paper provides an in-depth review on the topic. The released sources and transport of co-contaminated PAHs and heavy metals, including their co-occurrence through formation of cation-π interactions and their adsorption in soil are examined. Moreover, it is investigated that co-contamination of PAHs and heavy metals can drive a synergistic positive influence on bioremediation through enhanced secretion of extracellular polymeric substances (EPSs), production of biosynthetic genes, organic acid and enzymatic proliferation. However, PAHs molecular structure, PAHs-heavy metals bioavailability and their interactive cytotoxic effects on microorganisms can exert a challenging influence on the bioremediation under co-contaminated conditions. The fluctuations in bioavailability for microorganisms are associated with soil properties, chemical coordinative interactions, and biological activities under the co-contaminated PAHs-heavy metals conditions. The interactive cytotoxicity caused by the emergence of co-contaminants includes microbial cell disruption, denaturation of DNA and protein structure, and deregulation of antioxidant biological molecules. Finally, this paper presents the emerging strategies to overcome the bioavailability problems and recommends the use of biostimulation and bioaugmentation along with the microbial immobilization for enhanced bioremediation of PAHs-heavy metals co-contaminated sites. Better knowledge of the bioremediation potential is imperative to improve the use of these approaches for the sustainable and cost-effective remediation of PAHs and heavy metals co-contamination in the near future.

Effects of co-occurrence of PFASs and chlorinated aliphatic hydrocarbons on microbial communities in groundwater: A field study.

The effects of per- and polyfluoroalkyl substances (PFASs) and chlorinated aliphatic hydrocarbons (CAHs) co-contamination on the microbial community in the field have not been studied. In this study, we evaluated the presence of PFASs and CAHs in groundwater collected from a fluorochemical plant (FCP), and carried out Illumina MiSeq sequencing to understand the impact of mixed PFASs and CAHs on the indigenous microbial community. The sum concentrations of 20 PFASs in FCP groundwater ranged from 2.05 to 317.40 µg/L, and the highest PFOA concentration was observed in the deep aquifer (60 m below ground surface), co-contaminated by dense non-aqueous-phase liquid (DNAPL). The existence of PFASs and CAHs co-contamination in groundwater resulted in a considerable decrease in the diversity of microbial communities, while the abundance of metabolisms associated with contaminants biodegradation has increased significantly compared to the background wells. Furthermore, Acinetobacter, Pseudomonas and Arthrobacter were the dominant genera in PFASs and CAHs co-contaminated groundwater. The presence of high concentrations of PFASs and CAHs has been positively associated with the genus of Citreitalea. Finally, geochemical parameters, such as ORP, sulfate and nitrate were the key factors to shape up the structure of the microbial community and sources to rich the abundance of the potential functional bacteria.

In situ remediation of Cr(VI) contaminated groundwater by ZVI-PRB and the corresponding indigenous microbial community responses: a field-scale study.

The performance of a permeable reactive barrier (PRB) for the in situ remediation of hexavalent chromium [Cr(VI)] contaminated groundwater, and the resulted responses in the indigenous microbial community, were investigated in a field-scale study. The PRB consisted of a mixture of zero-valent iron (ZVI), gravel and sand. The results showed that the PRB segment with 20% active reaction medium (ZVI) was able to successfully reduce Cr(VI) via chemical reduction from 27.29-242.65 mg/L to below the clean-up goal of 0.1 mg/L, and can be scaled-up under field conditions. It was found that the ZVI induced significant changes in the indigenous microbial community structure and compositions in the area of the PRB and those areas downgradient. The competitive growth among Cr(VI)-reducing bacteria (the reduced abundance of Hydrogenophaga, Pseudomonas, Exiguobacterium and Rhodobacter, along with the enrichment of Rivibacter and Candidatus_Desulforudis) were observed in PRB. In addition, Cr(VI)-reducing bacteria (Hydrogenophaga, Pseudomonas, Exiguobacterium and Rhodobacter) were enriched in the downgradient of PRB, indicating that Cr(VI) can be further bio-reduced to Cr(III). The Cr(VI) bio-reduction could serve as a secondary mechanism for further removal of Cr(VI) from contaminated groundwater, suggesting that the actual lifetime of a PRB can be prolonged, which is important for the design and economic assessment of a PRB. Further analysis revealed that pH, dissolved oxygen, Cr(VI) level, the oxidation-reduction potential, and temperature were the main environmental factors influencing the subsurface microbial community compositions.

Enzyme-mimic activity of ferric nano-core residing in ferritin and its biosensing applications.

Ferritins are nanoscale globular protein cages encapsulating a ferric core. They widely exist in animals, plants, and microbes, playing indispensable roles in iron homeostasis. Interestingly, our study clearly demonstrates that ferritin has an enzyme-mimic activity derived from its ferric nanocore but not the protein cage. Further study revealed that the mimic-enzyme activity of ferritin is more thermally stable and pH-tolerant compared with horseradish peroxidase. Considering the abundance of ferritin in numerous organisms, this finding may indicate a new role of ferritin in antioxidant and detoxification metabolisms. In addition, as a natural protein-caged nanoparticle with an enzyme-mimic activity, ferritin is readily conjugated with biomolecules to construct nanobiosensors, thus holds promising potential for facile and biocompatible labeling for sensitive and robust bioassays in biomedical applications.