Уточнить поиск
Результаты 2591-2600 из 4,896
Modulating the Effect of Iron and Total Organic Carbon on the Efficiency of a Hydrogen Peroxide-Based Algaecide for Suppressing Cyanobacteria
2019
Crafton, Elizabeth A. | Cutright, Teresa J. | Bishop, West M. | Ott, Donald W.
The intensity and frequency of cyanobacteria-dominated harmful algal blooms (cHABs) has been increasing. A key issue associated with cHABs is the potential to release cyanotoxins, such as microcystin. One of the primary methods for addressing cHABs in a reservoir is the application of algaecides. This research evaluated the impact of common environmental factors (i.e., Fe, total organic carbon) on the efficacy of a hydrogen peroxide-based algaecide to attain control of a targeted cyanobacterial population. The results found that sodium carbonate peroxydrate (SCP, trade name PAK®27) at half the manufacturer’s suggested application was effective at suppressing cyanobacteria for 2 weeks. For example, reactors that contained a full level of TOC and 1 mg/L Fe significantly decreased by 89% from 21,899 to 2437 ± 987 cells/mL (p < 0.05) by 2 days after treatment with half-dose SCP while reactors that contained the full-dose TOC and no SCP treatment depicted an increase in cyanobacteria population over the first week. Furthermore, as the cyanobacteria population decreased, the algal assemblage began to switch to being green algae dominant. Under the experimental conditions evaluated, Fe and total organic content did not interfere with the efficacy of SCP. SCP can provide effective control of cyanobacteria in a variety of environmental conditions.
Показать больше [+] Меньше [-]Windbreak Wall-Vegetative Strip System to Reduce Air Emissions from Mechanically Ventilated Livestock Barns: Part 2—Swine House Evaluation
2019
ʻAjamī, ʻAlī | Shah, Sanjay B. | Wang-Li, Lingjuan | Kolar, Praveen | Castillo, Miguel S.
Air emissions from animal feeding operations (AFOs) can affect public health, environment, and quality of life. Although regulations or lawsuits may force AFOs to reduce air emissions, treatment options are limited and expensive. Trapping particulate matter (PM) emitted from AFOs is important for reducing emissions since many odorous and environmentally important gases are also transported on PM. Since PM emitted by AFOs have relatively high particle density and diameter, its partial filtration might be feasible and effective in reducing air emission. A porous windbreak wall made of lumber and mosquito screen, coupled with a vegetative strip of switchgrass (Panicum virgatum) covering three fans, was evaluated in a tunnel-ventilated swine finishing barn. The system imposed acceptable pressure on the fan (< 13 Pa) and was readily cleaned by rain. The system reduced total suspended particulate (TSP) emission moderately (average reduction of 28%), while reduction in ammonia emissions was low. Odor 10 m downstream of the fans was reduced greatly by 71%. Soil inside the system and vegetation accumulated appreciable amounts of nitrogen and sulfur; the vegetation also trapped appreciable amounts of PM. Overall, this low-cost, retrofittable, and modular system could be used by swine farmers to reduce their emissions, alone or in combination with other mitigation methods to obtain greater reduction in emissions.
Показать больше [+] Меньше [-]Dynamic simulation of the optimal allocation of water resources via the introduction of integrated water environmental policies in Baoding, China
2019
Mou, Siyu | Yan, Jingjing | Sha, Jinghua | Li, Shule | Ma, Yufang | He, Gengyu | Song, Ci
With rapid industrialization and urbanization, regional water shortages and water quality deterioration have posed great challenges for the sustainable development of cities in North China, especially those with a large demand for agricultural irrigation water. Based on an input-output analysis, this paper develops a dynamic optimization model consisting of three sub-models and multiple constraint conditions to solve the water crisis of Baoding, a typical city experiencing water shortages and serious water pollution in North China. The water resource carrying capacity (WRCC) indicator is introduced in the analysis of the results to comprehensively assess the effect of integrated water environmental policies (IWEPs) from 2013 to 2025. In the optimal scenario, the annual chemical oxygen demand (COD) discharge and annual water demand in Baoding can be reduced by 2.6% and 0.6%, respectively, with an annual gross regional product (GRP) growth rate of 7.52%. The WRCC can be improved from moderately overloaded to weakly unsaturated, which indicates that water resources can meet the socioeconomic development requirements. The results demonstrate the effectiveness of the linear optimization model with input-output analysis in coordinating the relationships among water demand, water environment protection, and economic development, and the IWEPs provide an applicable reference for decision-makers in Baoding and other similar cities in North China to address deteriorating water systems.
Показать больше [+] Меньше [-]Pentachlorophenol Removal from Water by Soybean Peroxidase and Iron(II) Salts Concerted Action
2019
Tolardo, Valentina | García-Ballesteros, Sara | Santos-Juanes, Lucas | Vercher, Rosa | Amat, Ana M. | Arques, Antonio | Laurenti, Enzo
Soybean peroxidase (SBP) has been employed for the treatment of aqueous solutions containing pentachlorophenol (PCP) in the presence of hydrogen peroxide at pH range 5–7. Reaction carried out with 1 mg/L of PCP, 4 mg/L of H₂O₂, and 1.3 × 10⁻⁹ M of SBP showed a fast initial elimination of PCP (ca. 30% in 20 min), but the reaction does not go beyond the removal of 50% of the initial concentration of PCP. Modification in SBP and PCP amounts did not change the reaction profile and higher amounts of H₂O₂ were detrimental for the reaction. Addition of Fe(II) to the system resulted in an acceleration of the process to reach nearly complete PCP removal at pH 5 or 6; this is more probably due to a synergetic effect of the enzymatic process and Fenton reaction. However, experiments developed in tap water resulted in a lower PCP elimination, but this inconvenience can be partly overcome by leaving the tap water overnight in an open vessel before reaction.
Показать больше [+] Меньше [-]Enhanced Bioremediation of Heavy Metal Contaminated Landfill Soil Using Filamentous Fungi Consortia: a Demonstration of Bioaugmentation Potential
2019
Hassan, Auwalu | Pariatamby, Agamuthu | Ahmed, Aziz | Auta, Helen Shnada | Hamid, Fauziah Shahul
This study aimed to determine the mycoremediative capacity of filamentous fungi consortia in landfill heavy metal contaminated soil. Streak plate method was utilized for the isolation of fungi from the landfill soil. Isolates were identified using morphological and molecular techniques. Heavy metal tolerance of the fungi was determined using radial growth diameter technique. Twelve species of landfill indigenous fungi were used for the bioremediation process. Two categories of fungi consortia namely highly tolerant fungi (Perenniporia subtephropora, Daldinia starbaeckii, Phanerochaete concrescens, Cerrena aurantiopora, Fusarium equiseti, Polyporales sp., Aspergillus niger, Aspergillus fumigatus, and Trametes versicolor) and moderately tolerant fungi (Paecilomyces lilacinus, Antrodia serialis, and Penicillium cataractum) were used to amend the contaminated soil; meanwhile, the unamended soil served as control. Maximum tolerance index of 1.0 was reported in Cr-, Cu-, and Fe-amended PDA medium. Meanwhile, the maximum heavy metal bioremoval efficiencies were for highly tolerant fungal consortium treated soil and were recorded as As (62%) > Mn (59%) > Cu (49%) > Cr (42%) > Fe (38%). Likewise, the maximum metal removal rate constant (K) and the half-lives (t₁/₂) were 0.0097/day 71 days, 0.0088/day 79 days, 0.0067/day 103 days, 0.0054/day 128 days, and 0.0048/day 144 days for As, Mn, Cu, Cr, and Fe, respectively, which were all for soil treated with consortium of highly tolerant fungi (P. subtephropora, D. starbaeckii, P. concrescens, C. aurantiopora, F. equiseti, Polyporales sp., A. niger, A. fumigatus, and T. versicolor). Spectra analysis revealed a clear distinction in the functional groups between the fungal treated and the untreated soils. Peaks at 874 ± 2 cm⁻¹ and 1425 ± 2 cm⁻¹ were only found in fungi amended soil. Physicochemical parameters mainly pH and redox potential played a key role in the bioremediation process, and bioaccumulation was believed to be the favored mechanism for the metal bioremoval. The data are suitable for assessing the contribution of bioaugmentation with consortia of fungi. It is equally important for assessing the synergistic effect of fungi on the reduction of extractable heavy metals in contaminated soil.
Показать больше [+] Меньше [-]Aqueous Film-Forming Foams (AFFFs) Are Very Toxic to Aquatic Microcrustaceans
2019
da Silva, Silvana Carmo | Pusceddu, Fabio Hermes | dos Santos Barbosa Ortega, Andressa | de Souza Abessa, Denis Moledo | Pereira, Camilo Dias Seabra | Maranho, Luciane Alves
The use of aqueous film-forming foams (AFFFs) have been related to environmental contamination due to handling, storage, and use in the firefighting against class B fire. Studies have associated the use of AFFFs with toxic effects from its perfluorinated compounds (PFCs) to the aquatic ecosystem, which led the Stockholm Convention to restrict their use. In Brazil, despite the large-scale use, there is no data on employment or annual commercialization of these products. This study evaluated the toxicity of seven brands of AFFFs used in the firefighting of the petrochemical’s terminal of fuel storage in Port of Santos (Santos, São Paulo, Brazil) which occurred in 2015, in which more than 61,000 L of AFFFs drained into the adjacent aquatic ecosystems. The toxicity evaluation was performed by means of the acute bioassay using the freshwater microcrustacean Daphnia similis. The AFFF brands tested were considered toxic to D. similis, including at much lower dilutions than those recommended by the manufacturers. The brand that showed the lowest toxicity was Kidde Sintex® 3% × 6%, followed by Kidde Sintex® 1% × 3%, Argus Prime®, Cold Fire®, Ageofoam®, and Liovac®, and the one with the highest toxicity was F-500 fire®. These results provide valuable information for the development of public policies aimed at managing the AFFF discharge in freshwater ecosystems.
Показать больше [+] Меньше [-]Effect of acute gold nanorods on reproductive function in male albino rats: histological, morphometric, hormonal, and redox balance parameters
2019
Hassan, Arwa A. | Abdoon, Ahmed Sabry S. | Elsheikh, Sawsan M. | Khairy, Mohamed H. | Gamaleldin, Amina A. | Elnabtity, Sameh M.
In this study, we investigated the effect of acute administration of gold nanorods (AuNRs) on testicular function, sexual hormones, and oxidative stress parameters in male albino rats. Forty mature male albino rats were divided into two equal groups (n = 20/each). The first group received 1 ml saline solution intraperitoneally (i.p.). The second group received single i.p. injection of 75 μg 50 nm AuNRs/kg/bwt. Five rats from each group were sacrificed on days 1, 3, 7, and 14 post treatment and blood samples were collected for hormonal and biochemical analysis. Testes were collected from each group at each time point for histopathology, morphometric, and transmission electron microscope analyses of testis and epididymis. Results indicated that i.p. injection of AuNRs did not produce any histopathological changes. Morphometric analysis of testicular samples revealed that the height of lining epithelium was significantly (P < 0.05) higher in AuNR group on days 3 and 14 post treatment, and the minor axis of seminiferous tubules was higher (P < 0.05) in AuNR-injected rats than in control group. For the epididymis, the number of spermatozoa was significantly (P < 0.05) higher on days 7 and 14 after AuNR injection when compared with control rats. AuNRs were not detected by TEM at all time points of the experiment. Serum analysis demonstrated that total and free testosterone values significantly (P < 0.05) increased on days 1, 3, 7, and 14 post AuNR injection. LH was higher (P < 0.05) in AuNRs-injected rats on days 3, 7, and 14 post injection, while FSH values were higher (P < 0.05) in AuNR group on days 3 and 14. Malondialdehyde significantly (P < 0.05) decreased on days 3, 7, and 14 in AuNR group, while catalase, glutathione peroxidase, and superoxide dismutase values were significantly (P < 0.05) elevated on days 3, 7, and 14 in AuNRs-injected rats compared with control group. In conclusion, intraperitoneal injection of 50 nm AuNRs is safe on the reproductive function and has an antioxidant action.
Показать больше [+] Меньше [-]Low Threat by Sulphate Particles and Ozone on Tufa at Plitvice Lakes National Park
2019
Kovač-Andrić, Elvira | Matasović, Brunislav | Radanović, Tatjana | Šrajer Gajdošik, Martina
Plitvice Lakes National Park presents one of the most beautiful karst complexes in the world. Its waters are supersaturated with dissolved calcium carbonate (calcite) which is released and deposited in the form of tiny crystals as a result of water splashing at tufa barriers. Sulphates, present in the particulate matter (PM), can be deposited on the surface of the calcite. In the air, sulphate particles are formed by the oxidation of SO₂ in a series of chemical reactions as reported by Li et al. (Atmospheric Chemistry and Physics 6:2453–2464, 2006). Fast oxidation of SO₂ in nature can also take place on the surface of the calcite in the presence of ozone and is significantly enhanced by high humidity as reported by Li et al. (Atmospheric Chemistry and Physics 6:2453–2464, 2006) and Massey (Science of the Total Environment 227(2–3), 109–121, 1999). The resulting sulphates can destroy the surface of the calcite and indirectly influence the composition and quality of water. Hourly concentrations of ozone, PM₁₀ and PM₂.₅ at the monitoring station Plitvice Lakes in the period from 2012 to 2014 are presented. After assessing the observed values of both PM and ozone, presently there are no significant danger for Plitvice Lakes. However, this can change in the future so continuous monitoring will be necessary in the future.
Показать больше [+] Меньше [-]Consumers’ knowledge, attitude and behavioural patterns towards the liquid wastes (cooking oil) in Istanbul, Turkey
2019
Gurbuz, Ismail Bulent | Ozkan, Gulay
This study was carried out to reveal the people’s knowledge level about the harmful effects of waste oils, especially waste cooking oil, on the environment. It also aims to understand the attitude and behavioural patterns related to the safe disposal of them. Istanbul is chosen because it represents the entire country with its diverse socio-demographic and socio-cultural structure. A total of 408 respondents were randomly chosen and interviewed in the designated regions. The research data were obtained by using a structured survey consisting demographic and Likert scale questions. SPSS 23.0 statistical software was used to analyse the survey data. Results suggest that despite the high educational level, participants did not know that household liquid waste has a negative impact on the environment. They disagreed on the statement that liquid waste can damage water resources. Public spots, and formal and informal education were not found effective and failed to make the desired impact. Majority of participants did not know their duties in the disposal of waste. They also did not know where the liquid waste collection units were and what projects were being implemented in their neighbourhood. Fewer participants were concerned at what point and how the hazardous liquid wastes collected by municipalities were disposed of after leaving their habitat and whether these methods were reliable or acceptable. This research concludes that user behaviour was disappointing in cooking oil usage and waste oil disposal. The collection of waste cooking oils remains far below the developed countries.
Показать больше [+] Меньше [-]A dualistic water cycle system dynamic model for sustainable water resource management through progressive operational scenario analysis
2019
Peng, Jiayu | Lu, Shaoyong | Cao, Yimei | Wang, Xing | Hu, Xiaozhen | Wang, Minghao | Zheng, Binghui
A reliable system simulation of the reciprocal mechanism between water resource utilization and dualistic water cycle is essential to the basin water resource sustainability management. In this study, a system dynamic model was built to simulate the water cycle change and lake water environmental pressure under the influence of water resources utilization, and the procedure of a progressive operational scenario analysis of how to relieve water environment pressure was illustrated. Dianchi Lake, which is the sixth largest and the most severely polluted freshwater lake in China, was employed as a case study to demonstrate the applicability of the model. The change of runoff components and pollution load of total nitrogen from 2000 to 2030 were discussed. Also, the sustainable water resource management was ultimately realized in the planning period through three progressive levels of water resource regulation scenarios. Compared with business-as-usual scenario, the TN pollution load into lake and total water demand decrease by 27.1 and 27.3%, and the domestic water use, industry water use, tertiary industry water use, and irrigation decrease 9.0, 16.8, 29.5, and 30% in the scenario 3.
Показать больше [+] Меньше [-]