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Isolation of urease-producing bacteria and their effects on reducing Cd and Pb accumulation in lettuce (Lactuca sativa L.) Full text
2020
Wang, Tiejun | Wang, Shilin | Tang, Xingchun | Fan, Xianpeng | Yang, Sheng | Yao, Lunguang | Li, Yadong | Han, Hui
Excess Cd and Pb in agricultural soils enter the food chain and adversely affect all organisms. Therefore, it is important to find an eco-friendly way to reduce heavy metal accumulation in vegetables. We used urea agar plates to isolate urease-producing bacteria from the rhizosphere soil of lettuce in Cd- and Pb-contaminated farmland and investigated their ability to produce urease and immobilize heavy metals. The effects of these strains on the biomass, quality, and Cd and Pb accumulation of lettuce were also studied. The results showed that two urease-producing bacteria, Enterobacter bugandensis TJ6 and Bacillus megaterium HD8, were screened from the rhizosphere soil of lettuce. They had a high ability to produce urease (44.5 mS cm⁻¹ min⁻¹ OD₆₀₀⁻¹ and 54.2 mS cm⁻¹ min⁻¹ OD₆₀₀⁻¹, respectively) and IAA (303 mg L⁻¹ and 387 mg L⁻¹, respectively). Compared with the control, inoculation with strains TJ6 and HD8 reduced the Cd (75.3–85.8%) and Pb (74.8–87.2%) concentrations and increased the pH (from 6.92 to 8.13–8.53) in solution. A hydroponic experiment showed that the two strains increased the biomass (31.3–55.2%), improved the quality (28.6–52.6% for the soluble protein content and 34.8–88.4% for the vitamin C (Vc) content), and reduced the Cd (25.6–68.9%) and Pb (48.7–78.8%) contents of lettuce shoots (edible tissue). In addition, strain HD8 had a greater ability than strain TJ6 to reduce lettuce Cd and Pb uptake and water-soluble Cd and Pb levels in solution. These data show that the urease-producing bacteria protect lettuce against Cd and Pb toxicity by extracellular adsorption, Cd and Pb immobilization, and increased pH. The effects of heavy metal immobilization by the two strains can guarantee vegetable safety in situ for the bioremediation of heavy metal–polluted farmland.
Show more [+] Less [-]Antibiotic resistance gene profiling in response to antibiotic usage and environmental factors in the surface water and groundwater of Honghu Lake, China Full text
2020
Tong, Lei | Qin, Liting | Guan, Chuan | Wilson, Mesmire Emade | Li, Xianju | Cheng, Dandan | Ma, Jie | Liu, Hui | Gong, Fujun
There is an increasing concern that aquaculture has been implicated in the formation of antibiotic resistance gene (ARG) reservoirs; however, little is known about the consequences of their presence in groundwater. In this study, 22 antibiotics, including four acetylated metabolites, and 27 ARGs were analyzed in fish pond water, surface water, and groundwater of the Honghu Lake in China. Correlations between conventional parameters, ionic composition, antibiotic concentration, and relative abundance of ARGs in water samples were analyzed. Among the three different sources of water, total antibiotic levels were the highest in fish pond water and the lowest in groundwater, with moderate levels in lake water. In surface water, sulfonamides and their metabolites accounted for the highest antibiotic content, whereas tetracyclines were the most frequently found in groundwater samples. Despite the near-undetectable levels of antibiotics in groundwater, the relative abundance of ARGs in groundwater samples was even higher than that in surface waters. The magnitude and extent of ARG migration are likely to be dependent on local antibiotic contamination levels as well as on the local environmental and hydrogeological conditions, with the class 1 integrons (intI1) being essential for the dissemination of such ARGs. The effects of environmental parameters such as antibiotics, dissolved oxygen, HCO₃⁻, and pH on ARGs were highly significant, reflecting the potential impact of these factors on the abundance of ARGs. Our findings thus highlight the need for improved control of the spread of ARGs in and from aquaculture environments.
Show more [+] Less [-]Estimating alcohol consumption by using wastewater-based epidemiology in Adana Province, Turkey Full text
2020
Daglioglu, Nebile | Atasoy, Asli | Asadi, Anvar | Guzel, Evsen Yavuz | Dengiz, Huseyin
Increased alcohol consumption, especially among young people, is a major concern in Turkey as it is around the world due to negative effects on public health and safety. Regarding this, it is pivotal to monitor and therefore control alcohol use in public. In this case, wastewater-based epidemiology (WBE), which is the in-depth analysis of wastewater and a relatively new method, can deliver complementary information concerning the abuse of different substances. The proven potential of the WBE approach offers new promises in the process of monitoring alcohol use, namely the monitoring of the levels of ethyl sulfate (EtS) as a urinary biomarker of alcohol consumption, and it is a powerful mean to estimate alcohol use at the community level. In this study, raw 24-h composite wastewater samples were collected from Seyhan and Yüregir wastewater treatment plants (WWTPs) in Adana Province for one week per season (October 2016–August 2017). The fast and validated analytical method was performed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) and therefore applied to the analysis of ethyl sulfate (EtS). Obtained concentration values were back-calculated, and regional and temporal social usage rates were determined. Higher values were calculated for both WWTPs on Sunday. Alcohol consumption in the region served by Seyhan WWTP was higher than Yüregir WWTP. The results showed that the levels of alcohol consumption during given periods in Adana ranged from 659.8 to 8998.7 mL/day/1000 per person with an average value of 4983.9 and 3924.2 mL/day/1000 inhabitant in Seyhan WWTP and Yüregir WWTP, respectively. This study shows that weekly and annual trends in alcohol consumption can be detected quickly from wastewater analysis.
Show more [+] Less [-]Assessment of coastal ecosystems vulnerability to pollution: Algiers coast, Algeria Full text
2020
Silhadi, Mohamed Adlane | Refes, Wahid | Mazouzi, Sakina
Coastal areas are frequently influenced by direct and/or indirect multiple anthropogenic pressures, which impacts marine life. Those perturbations may act in a heterogeneous way with a different intensity and are related to the complexity of coastal ecosystems. To visualize all these interactions at a local scale, a methodology inspired from many researches has been implemented in order to search, identify, and classify coastal ecosystems according to their sensitivity to anthropic pressure exerted by coastal cities. Thus, producing vulnerability maps will be essential tools to local coastal managers. We have applied this methodology on five coastal municipalities in Algiers. Firstly, the environmental sensitivity of coastal ecosystems was assessed by analyzing these four sub-indices: biological sensitivity, geomorphological sensitivity, hydrodynamic characteristics, and pollution intensity. Secondly, an assessment of the anthropogenic pressures presented by each municipality was carried out. Five sub-indexes have been taken into consideration when conducting this assessment: human activities, infrastructures, vectors of pollution, urbanization, and regulatory protection. Then, vulnerability maps were produced by the overlapping of sensitivity and anthropic pressure maps. The results assessed for the environmental vulnerability indicated that most areas are moderately to highly vulnerable, especially in the municipalities of Bab El Oued, Rais Hamidou, and Ain Bénian. The analysis of the obtained results shows the potential applicability of this methodology because they accurately reflect the reality. Therefore, these results can be useful to decision-makers by providing them with a relatively rational decision-making tool to prioritize future management and planning efforts.
Show more [+] Less [-]Synthesis, characterization, and application of iron oxyhydroxide coated with rice husk for fluoride removal from aqueous media Full text
2020
Pillai, Parwathi | Lakhtaria, Yogesh | Dharaskar, Swapnil | Khalid, Mohammad
A novel nanoparticle (NPs) iron oxyhydroxide modified with rice husk (RH + FeOOH) was synthesized with wet chemical method. Batch study was performed to investigate fluoride removal and adsorption capacity. The RH + FeOOH NPs were characterized by using Fourier transform infrared spectroscopy, X-ray powder diffraction, Brunauer–Emmett–Teller, scanning electron microscope with energy dispersion, transmission electron microscope, and particle size analyzer. By varying parameters, batch adsorption with adsorption capacity was performed such as contact time, stirring rate, adsorbent dosage, temperature, initial concentration, and pH. The BET surface area and the pore volume of the FeOOH and RH + FeOOH were found to be 157 m² g⁻¹, 195 m² g⁻¹ and 0.136 m² g⁻¹, 0.224 m² g⁻¹. Based on kinetic study, pseudo-second-order was followed by regression coefficient (R²) 0.99. Langmuir isotherm model showed the best adsorption capacity of 26 mg g⁻¹. Moreover, the RH + FeOOH showed best affinity towards fluoride removal and may act as an excellent adsorbent for fluoride treatment from aqueous solution. Synthesis and Fluoride Adsorption Mechanism of Iron Oxyhydroxide Modified with rice husk
Show more [+] Less [-]Acrolein exerts a genotoxic effect in the Leydig cells by stimulating DNA damage-induced apoptosis Full text
2020
Yildizbayrak, Nebahat | Orta-Yilmaz, Banu | Aydin, Yasemin | Erkan, Melike
Acrolein is a highly reactive unsaturated organic molecule and has harmful effects on human health. Acrolein is generally formed in heat-treated foods above 150 °C, as well as in the combustion of gasoline, wood industry, plastic waste, and tobacco smoke. In this study, the effects of acrolein on genotoxicity in Leydig cells and the underlying mechanisms are aimed to be clarified. In addition, the toxicogenomic profile of acrolein was studied in terms of both apoptosis and steroidogenesis. Real-time PCR and ELISA tests were used to analyses of steroidogenic endpoints. Apoptosis was evaluated with double fluorescence staining and gene expression analyses of related genes. Comet assay was used to determine the genotoxicity. The results showed that acrolein caused concentration-dependent inhibition on cell viability at 8 μM and above concentrations, decreased testosterone production at 13.6 and 19.7 μM concentrations, and suppressed expression levels of genes that play an important role in steroidogenic pathway. Furthermore, acrolein downregulated expression of anti-apoptotic Bcl2 gene and upregulated expression of pro-apoptotic Bax, Casp3, and Trp53 gene after 24-h treatment in 7.4, 13.6, and 19.7 μM acrolein-exposed Leydig cells. The results of comet assay showed that acrolein significantly induced tail length, tail % DNA, and Olive tail moment. Overall, it was concluded that acrolein-induced cell damage in Leydig cells may be due to formation of genetic damage in steroidogenesis and apoptosis.
Show more [+] Less [-]Responses of soil nutrients and microbial communities to intercropping medicinal plants in moso bamboo plantations in subtropical China Full text
2020
Zhang, Xiaoping | Gao, Guibin | Wu, Zhizhuang | Wen, Xing | Zhong, Hao | Zhong, Zhezhe | Yang, Chuanbao | Bian, Fangyuan | Gai, Xu
Bamboo forests are one of the most important forest resources in subtropical China. A pure, single-layer bamboo forest is considered an optimal habitat for intercropping medicinal herbs. Soil microorganisms have an important role in various ecological processes and respond quickly to environmental changes. However, changes in soil nutrients and microbial communities associated with agroforestry cultivation methods remain poorly documented. In the present study, a pure moso bamboo (Phyllostachys edulis) forest (Con) and three adjacent moso bamboo–based agroforestry (BAF) systems (moso bamboo–Paris polyphylla (BP), moso bamboo–Tetrastigma hemsleyanum (BT) and moso bamboo–Bletilla striata (BB)) were selected; and their soil chemical properties and bacterial communities were studied and compared to evaluate the effects of agroforestry on soil bacterial communities and the relationship between soil properties and bacterial communities in BAF systems. Results showed that compared with soils under the Con, soils under the BAF systems had more (p < 0.05) soil organic carbon (SOC) and available nitrogen (AN) but lower (p < 0.05) pH and available potassium (AK). In addition, compared with the Con system, the BB and BT systems had significantly greater (p < 0.05) available phosphorus (AP). Compared with that in the Con system, the Shannon index in the BAF systems was significantly greater (p < 0.05), but the Chao1 index not different. On the basis of relative abundance values, compared with the Con soils, the BAF soils had a significantly greater abundance of (p < 0.05) Bacteroidetes and Planctomyces but a significantly lower abundance of (p < 0.05) Verrucomicrobia, Gemmatimonadetes and Candidatus Xiphinematobacter. Moreover, compared with the Con system, the BB and BT systems had a greater (p < 0.05) abundance of Actinobacteria, Rhodoplanes, Candidatus Solibacter and Candidatus Koribacter. Redundancy analysis (RDA) revealed that soil pH, SOC and AP were significantly correlated with bacterial community composition. Results of this study suggest that intercropping medicinal herbs can result in soil acidification and potassium (K) depletion; thus, countermeasures such as applications of K fertilizer and alkaline soil amendments are necessary for BAF systems.
Show more [+] Less [-]Catalytic reduction of nitrate with Pd-In2O3 Full text
2020
Pizarro, Alejandro Herrero | Torija, Irene | Moreno, Reyes | Arauzo, Jesús | Monsalvo, Victor M.
This work presents a novel catalyst preparation method and the optimization of operation conditions for an effective NO₃⁻ conversion with a high selectivity and stability that guarantee water quality for human consumption. Catalytic reduction of NO₃⁻ and NO₂⁻ was carried out with Pd supported on In₂O₃ under mild operation conditions (25 °C, 1 atm) with H₂ and CO₂ as reducing and acidifying agents, respectively. The catalyst was used in batch experiments showing the suppression of NO₂⁻ accumulation and low NH₄⁺ selectivity at acid pH. Long-term experiments were carried out with Pd on γ-Al₂O₃ spheres covered with In₂O₃. This catalyst presented a high stability during more than 700 h. A concentration of NO₃⁻ below 50 mg/L was achieved, producing less than 0.5 mg/L of NH₄⁺ as reaction by-product by a strict limitation of the H₂ fed and controlling several operating conditions.
Show more [+] Less [-]Home-based outsourced informal work by children and adolescents impacts sleep and leisure—a preliminary study Full text
2020
Pereira, Elizeu Chiodi | Ferreira, Ana Paula Sacone da Silva | Sato, Ana Paula Sayuri | Fischer, Frida Marina | Olympio, Kelly Polido Kaneshiro
Child labor is a serious and controversial issue. Despite governments establishing health policies prohibiting or restricting the age of entry to the job market, there is still a large number of working children and adolescents worldwide, particularly informal workers. This study aimed to evaluate the living and working conditions of adolescents. Work activities were home-based involving the production of jewelry and fashion jewelry, in a Brazilian city, Limeira, São Paulo. Participants were 11–17-year-old workers and non-workers, who answered a comprehensive questionnaire on their living and working conditions and filled out a time-budget protocol for 10 consecutive days. Both instruments were applied twice during both school and vacation terms. Chi-square/Fisher and Student’s t tests were used, and Bonferroni corrections were performed in the significance levels of the statistical methods. During school time, working children/adolescents had lower mean sleep duration (p < 0.01) than non-working ones. During vacation, non-working youths enjoyed longer leisure time (p < 0.04). Comparing school and vacation times, working youths showed no significant difference in daily routine (p > 0.05), while non-workers spent more time on leisure activities during the vacation period (p = 0.005). In summary, this study found that working at home had a deleterious effect on the sleep and leisure of the youths studied. These data should be considered as an exposome component (specific external exposure) in evaluations of long-term health endpoints and their possible causes.
Show more [+] Less [-]Evaluation of a nanoscale zero-valent iron amendment as a potential tool to reduce mobility, toxicity, and bioaccumulation of arsenic and mercury from wetland sediments Full text
2020
Chapman, Ellen Emily Vanessa | Moore, Christine | Campbell, Linda M.
Gold mining in the 1800s has led to the contamination of wetlands with introduced mercury (Hg) and geogenic arsenic (As). In situ risk management tools to reduce mobility and toxicity of Hg and As are needed to support natural restoration of impacted ecosystems. Here, we explored whether a nanoscale zero-valent iron (nZVI) slurry injected into two different contaminated wetland sediments can reduce Hg and As mobility to the overlaying water and toxicity to two aquatic invertebrates, burrowing mayflies (Hexagenia spp.) and Chinese mystery snails (Cipangopaludina chinensis). Total water Hg and As concentrations overlying both contaminated sediments were reduced by at least 75% and 88% respectively when treated with nZVI slurry. In the first sediment, juvenile snail survival increased from 75% in the untreated sediment to 100% in all nZVI treatments. The 2% nZVI treatment level was the only one with surviving mayflies (33%) and growth of juvenile snails. No snails or mayflies survived in the second sediment, regardless of nZVI treatment level. However, snails survived longer in this sediment with 4% and 8% nZVI. To improve reactivity of nZVI without increasing nZVI dose, future studies should investigate matrix-supported nZVI for reducing mobility and toxicity of As and Hg in wetland sediments.
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