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Результаты 3921-3930 из 4,937
Effects of mixed amendments on the phytoavailability of Cd in contaminated paddy soil under a rice-rape rotation system Полный текст
2019
Ran, Hongzhen | Guo, Zhaohui | Shi, Lei | Feng, Wenli | Xiao, Xiyuan | Peng, Chi | Xue, Qinghua
A field experiment was performed to study the effects of mixed amendments, namely lime + organic fertilizer (LO), lime + organic fertilizer + calcium-magnesium phosphate fertilizer (LOC), lime + organic fertilizer + sepiolite (LOS), and lime + organic fertilizer + calcium-magnesium phosphate fertilizer + sepiolite (LOCS), on the availability and uptake of Cd from contaminated paddy soil under a rice-rape (Oryza sativa L. and Brassica napus L.) rotation system. The results showed that the grain yields of rice and rape with mixed amendment-treated were slightly influenced, in that the soil pH significantly increased while the DTPA-extractable Cd content of the soil and Cd uptake by the rice and rape were significantly reduced. The uptake of Cd by brown rice decreased significantly (p < 0.05), by 55.9–59.3% and 69.6–75.5% in the 2016 and 2017 crops, respectively, compared with that of the control (CK). The Cd uptake by rapeseeds during the 2017 season observably (p < 0.05) decreased by 38.2 and 29.6% under LO and LOC treatments, respectively. The Cd concentrations in rapeseeds were 0.11–0.18 mg kg⁻¹ under all the treatments except LOCS treatment, which is lower than the National Standard of Pollutants in Food of China (GB 2762-2017, 0.2 mg kg⁻¹). From both economic and food safety standpoints, rape is recommended for Cd-contaminated soil because it has a low Cd accumulation ability. The results showed that the rice-rape rotation combined with LO or LOC application was useful for reducing the Cd content in both rice and rape in Cd-contaminated soil and the effects could be sustained at least for three crop seasons.
Показать больше [+] Меньше [-]Does dual reduction in chemical fertilizer and pesticides improve nutrient loss and tea yield and quality? A pilot study in a green tea garden in Shaoxing, Zhejiang Province, China Полный текст
2019
Xie, Shaowen | Feng, Hanxiao | Yang, Fen | Zhao, Zhide | Hu, Xuedi | Wei, Chaoyang | Liang, Tao | Li, Haitao | Geng, Yuanbo
Tea tree (Camellia sinensis) is a valuable and popular cash crop widely planted in tropical and subtropical areas of China. To increase tea yield and quality, high rates of chemical fertilizer and pesticide application have generally been used; however, increasing usage of fertilizers and pesticides does not always proportionally increase tea yield. Indeed, excessive nutrient inputs may cause serious agricultural non-point source pollution. A pilot study on dual reduction in fertilizers and pesticides was conducted in a green tea plantation in Shaoxing, Zhejiang Province, to explore the environmental effects of different fertilizer and pesticide managements (e.g., changes in soil properties and nutrient accumulation, nutrient inputs in runoff water) and to reveal the potential effects of the interaction of these two managements on tea yield and quality. Traditional formulas and rates of chemical fertilizers and pesticides were used as the baselines (100% usage); replacement with different proportions of organic fertilizer (i.e., 20%, 50% and 80%) and direct pesticide reductions of 30%, 50%, and 80% were tested. The results showed that proper management with organic fertilizer replacement can effectively mitigate soil acidification and nutrient deficiency in tea plantations, increase soil organic matter (OM) and ammonium nitrogen (NH₄-N) contents, and promote tea yield and quality. Moreover, managements with organic fertilizer replacement can markedly reduce the inputs of ammonium nitrogen (NH₄-N), nitrate nitrogen (NO₃-N), total phosphorus (TP), and total potassium (TK) in runoff water. Soil nutrient accumulation was the highest while the runoff nutrient input was the lowest at 20% organic fertilizer replacement. Experimental spraying of bifenthrin and chlorfenapyr revealed that these pesticides were mainly trapped by the tea leaves and rarely entered the soil or water bodies. Although pesticide reduction treatments can effectively decrease pesticide residues in tea leaves, differences in pesticide residue between various treatments were not obvious due to the rapid degradation of pesticides. Multivariate analysis of variance showed that 50% of the variation in tea yield, bud density, polyphenols, and caffeine can be explained by interactions between fertilizers and pesticides. Combinations of 20% or 50% organic fertilizer replacement and 30% or 50% pesticide application reduction are appropriate for both mitigating nutrient loss and balancing tea yield and quality, especially the combination of 50% organic fertilizer replacement and 50% pesticide reduction, which produced the best results. This study demonstrates the feasibility of dual reductions in fertilizers and pesticides for mitigating environmental hazards while maintaining the yield and quality of tea.
Показать больше [+] Меньше [-]Exposure to ambient PM2.5 during pregnancy and preterm birth in metropolitan areas of the state of Georgia Полный текст
2019
Zhu, Jianmin | Lee, Rina Won | Twum, Claudia | Wei, Yudan
A number of studies has pointed to air pollution as an additional factor that could be associated with preterm birth. We assessed in this study the association between exposure to PM₂.₅ in ambient air during pregnancy and preterm birth in metropolitan areas of the state of Georgia, where the rate of preterm birth has been among the highest in the nation over the years. Birth data were obtained from the National Center for Health Statistics natality dataset. The study population consisted of 53,094 singleton live births between January 1 and December 31, 2004 in nine metropolitan counties of Georgia. Preterm birth was defined as birth, which occurs before 37 weeks of gestation. County-level daily air quality index (AQI) data obtained from the US Environmental Protection Agency (EPA) was used to estimate individual exposure levels of PM₂.₅ for each study participant based on the county of residence for the duration of the pregnancy. A multivariate logistic regression analysis was conducted to assess the association, adjusting for potential confounders. Of the infants whose mothers resided in the nine metropolitan counties of Georgia, 4543 (8.6%) were born preterm. A higher rate of preterm birth (9.8%) was observed in infants whose mothers were exposed to ambient PM₂.₅ with AQI values > 50 than the ones with AQI ≤ 50 (EPA standard for good air quality conditions). Mothers with exposure to PM₂.₅ at average AQI values greater than 50 during the entire pregnancy were at increased risk of preterm birth (odds ratio 1.15; 95% CI 1.07, 1.25), after adjusting for sex of infant, mother’s age, race/ethnicity, education, marital status, prenatal care, cigarette smoking, alcohol consumption, and season of conception. The study provides more evidence on the role of PM₂.₅ in preterm birth. Reducing exposure to ambient particulate matter, especially in urban areas, for pregnant women would be necessary to improve the health of infants.
Показать больше [+] Меньше [-]Evaluation of the quality and quantity of compost and leachate from household waterless toilets in France Полный текст
2019
Nasri, Behzad | Brun, Florent | Fouché, Olivier
One of the most undesired wastes is the human excreta due to the socio-environmental pressure. Otherwise, the nutriments contained in human excreta could be used as fertilizers to enrich the soil. Familial waterless litter composting toilets (FWLCT) are an alternative for locations where a centralized sewerage network cannot be provided or where there is a lack of standard urban infrastructure including roads, electricity, and water supply. The scientific researches on the composting techniques, the methods of control of the composting processors, and the rate of produced leachate are very limited. In this research, the composting systems included a feces and urine collection device. In each passage, the litter (carbonaceous material) is added to the excreta. Regularly, the buckets were emptied into a composting device located outside the house to which an additional portion of carbonaceous materials can be added. Monitoring was carried out on five rural and one urban familial composting areas in France for 1.5 years. The physiochemical and microbiological properties of the compost and leachate have been monitored and measured in compliance with the protocols. The results show that one of the main problems of this system of human excreta treatment is that the composting process does not achieve a significant rise in temperature and does not allow reaching the optimum temperatures (> 50 °C). Otherwise, from an agronomic point of view, the obtained compost is not rich enough in nutriments to be a good compost as soil fertilizer. But it can be used as a soil conditioner. The average leachate flux from the composters is 1.79 L/day. Because of the very short stay time in the piles, the leachate is contaminated by harmful bacteria and should be treated by another sanitation system.
Показать больше [+] Меньше [-]Effect of iron plaque and selenium on mercury uptake and translocation in rice seedlings grown in solution culture Полный текст
2019
Zhou, Xin Bin | Li, Ying Ying
A hydroponics experiment was conducted to investigate the effect of iron plaque on root surfaces and selenium (Se) on the uptake and transfer of mercury (Hg) in rice seedlings by adding in the EDTA-Fe (0, 10, 30, 50, 70 mg Fe l⁻¹) into the solution to produce a different amount of iron plaque outside rice root. After 24 h, the red-brown iron plaque was formed on the root surface, and the amount of iron plaques was positively correlated with the amount of Fe in the solution. The iron plaque deposited on the root surface has a strong adsorption effect on the inorganic Hg. The addition of Se could promote the adsorption of Hg²⁺ on the iron plaque of rice, and the introduction of Se could increase the adsorption capacity of Hg on iron plaque on average by 1.42 times. The Hg was extracted by DCB (Dithionite-citrate-bicarbonate) up to between 66.2 and 67.8% of the total Hg when the roots with iron plaque (Fe70) were incubated with the combination of 5 μmol L⁻¹ of HgCl₂ and 5 μmol L⁻¹ of Na₂SeO₃ for an hour. After 3 days, the content of Hg in the iron plaque decreased to 6.3–33.9%, indicating that part of the inorganic Hg adsorbed by the iron plaque could be reabsorbed and used. Besides that, the iron plaque allowed the Hg to stay longer in the iron plaque, which hindered the transfer of Hg to the shoot significantly. Hg adsorbed in the iron plaque can be desorbed by low-molecular-weight organic acids, which was equivalent to desorption of Hg from ferric hydroxide oxides. Hg adsorbed on the iron plaque can be moved back to the rest of the plant. These results suggest that the iron plaque and Se in the root surface might play a role as “physical buffer” in the absorption and transfer of Hg.
Показать больше [+] Меньше [-]Impact of dust storm on phytoplankton bloom over the Arabian Sea: a case study during March 2012 Полный текст
2019
Bali, Kunal | Mishra, Amit Kumar | Singh, Sachchidanand | Chandra, Subhash | Lehahn, Yoav
Dust storms affect the primary productivity of the ocean by providing necessary micronutrients to the surface layer. One such dust storm during March 2012 led to a substantial reduction in visibility and enhancement in aerosol optical depth (AOD) up to ~ 0.8 (AOD increased from 0.1 to 0.9) over the Arabian Sea. We explored the possible effects and mechanisms through which this particular dust storm could impact the ocean’s primary productivity (phytoplankton concentration), using satellite-borne remote sensors and reanalysis model data (2003–2016). The climatological analyses revealed anomalous March 2012 in terms of dust deposition and enhancement in phytoplankton concentration in the month of March during 2003–2016 over this region. The studied dust storm accounts for increase in the daily average surface dust deposition rate from ~ 3 to ~53 mg m⁻² day⁻¹, which is followed by a significant enhancement in the chlorophyll-a (Chl_a) concentration (~ 2 to ~9 mg m⁻³). We show strong association between a dust storm and an event of anomalously high biological production (with a 4-day forward lag) in the Arabian Sea. We suggest that the increase in biological production results from the superposition of two complementary processes (deposition of atmospheric nutrients and deepening of the mixed layer due to dust-induced sea surface temperature cooling) that enhance nutrient availability in the euphotic layer.
Показать больше [+] Меньше [-]Bacopa phospholipid complex retrieves aluminum maltolate complex–induced oxidative stress and apoptotic alterations in the brain regions of albino rat Полный текст
2019
Tirumanyam, Madhavi | Nadella, Rasajna | Kondammagari, Saritha | Borelli, Deva Prasad Raju | Nannepaga, John Sushma
Highly bioavailable plant phospholipid complex that can reverse aluminum maltolate (AlM)–induced toxicity is not yet reported. Hence, the present study was planned to investigate the impact of oxidative stress and apoptotic changes provoked by Al and ameliorative role of Bacopa phospholipid complex (BPC) in albino rats. The levels of antioxidant enzymes such as superoxide dismutase (SOD), catalase activity (CAT), glutathione peroxidase (GPx), and thiobarbituric acid–reactive substance (TBA-RS) were measured and immunohistochemistry analysis of apoptotic markers, Bax and Bcl-2, was done from the four brain regions such as the hippocampus, cerebral cortex, cerebellum, and medulla oblongata. The levels of antioxidant enzymes and apoptotic markers that were decreased on AlM induction showed a significant increase in their levels, almost as observed in the control, when treated with BPC and Bm. Our results indicate that both BPC and Bm showed a therapeutic effect against AlM toxicity; however, it was found that the therapeutic potential of BPC was more pronounced than Bm against AlM-induced neurotoxicity.
Показать больше [+] Меньше [-]The impact of humic acid on toxicity of individual herbicides and their mixtures to aquatic macrophytes Полный текст
2019
Mihajlović, Varja | Tomić, Tanja | Tubić, Aleksandra | Molnar Jazić, Jelena | Ivančev Tumbas, Ivana | Šunjka, Dragana | Lazić, Sanja | Teodorović, Ivana
This study investigates the impact of humic acid (HA) on the toxicity of selected herbicides and their binary mixtures to aquatic plants. The focus was on two auxin simulators (2,4-D and dicamba) and two photosynthetic inhibitors (atrazine and isoproturon). The results suggested that the addition of HA to the standard synthetic medium does not affect Lemna minor growth nor the toxicity of atrazine, but increases the toxicity of 2,4-D and the binary mixture of atrazine and 2,4-D. The addition of HA to the standard synthetic medium reversibly decreased the growth (biomass) of Myriophyllum aquaticum and enhanced the toxicity of individually tested herbicides (isoproturon and dicamba) as well as their binary mixture. The results showed delayed toxic effects of auxin simulators, especially 2,4-D in the Lemna test. The recovery after the exposure to individual photosystem II inhibitors (atrazine and isoproturon) is fast in both plant species, regardless of the presence of HA. In the case of selected mixtures (atrazine + 2,4-D and isoproturon + dicamba), recovery of both plant species was noted, while the efficiency depended on the herbicide concentration in the mixture rather than the presence or absence of HA.
Показать больше [+] Меньше [-]Prevalence of antibiotic resistance genes in cell culture liquid waste and the virulence assess for isolated resistant strains Полный текст
2019
Wang, Haichao | Wang, Jin | Li, Shuming | Li, Jinzhao | Jing, Chuanyong
Cell culture liquid waste containing antibiotic resistance genes (ARGs) and microbial community were still not received enough recognition, which pose potential risks to human health. Sixty-eight resistance genes and intl1 were detected in eight samples by Quantitative real-time PCR, while intl1 was only detected in hospital group. Meanwhile, the bacterial community was complex and diverse in each sample by 16S rRNA gene high-throughput sequencing, in addition, Morganella and Enterococcus presented a significant difference between two groups. Whole genome shotgun sequencing revealed that Morganella morganii had more resistance genes and virulence factors in hospital group, and three extended-spectrum beta-lactamase (ESBL) genotypes were found to be blaDHA-5, blaOXA-1, and blaTEM-1. This study provided a preliminary report on ARGs and resistant strains, which reminded people attention to the health risks of potential pathogens in this waste.
Показать больше [+] Меньше [-]Using stress wave technology for leakage detection in a landfill impervious layer Полный текст
2019
Chen, Yayu | Sun, Huanyi | Zhang, Wei | Huang, Xiaosong
This paper proposes a stress wave monitoring method for monitoring and locating leakage through the impervious layer at a landfill to resolve the “first pollution, then discovery” problem caused by the existing electrical monitoring method. The experimental results show that the linear distance to the geophones from the leak point should be less than 31.5 m to provide a well-defined rupture signal. The amplitudes of the stress wave signals generated during the yield and rupture stages of the high-density polyethylene (HDPE) film are more obvious and easily identified by the geophones; the rupture signal duration is approximately 100 ms, and the bandwidth is distributed within 0 kHz to 1 kHz. By studying the stress wave first arrival times calculated by the picking model, the average error of the picking model is approximately 0.35 ms, and the iteration of the model is ceased when the thresholds of the discriminating indices are 3.5 and 0.9. Experiments reveal that the positioning model should stop iterating when the absolute value of each element in the calibration vector is less than 140. The average positioning error is 0.248 m, and the maximum fiducial errors of the positioning model in the X-axis and Y-axis directions are 0.32% and 0.58%, respectively.
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