خيارات البحث
النتائج 4191 - 4200 من 8,010
Development and Optimization of Bioretention Systems with Modified Fillers of Corn Straw Biochar النص الكامل
2021
Li, Jiake | Li, Ning | Liu, Fang | Li, Yajiao
Bioretention systems have been proved to be a natural approach for effectively reducing stormwater runoff pollution loads. The filler is essential for the function of the bioretention systems; there are few studies on the use of biochar for bioretention. In this study, corn straw was used as raw material to prepare biochar bioretention-improved filler, and the optimal preparation scheme and filler proportioning method were determined. Three layered bioretention columns, i.e., BSM (bioretention soil media), BSM + 5%WTR (water treatment residues, w/w) and BSM + 5%CSC (corn straw biochar, w/w), were built to analyze its regulating effect on rainwater runoff. The DRAINMOD model was established based on the test results to analyze the regulating effect in different situations. The key parameters of the bioretention systems were optimized using response surface methodology (RSM). The results show that: BSM + 5%CSC was more stable than BSM + 5%WTR for water volume control effect and was better than BSM. The load reduction rates of BSM + 5%CSC was better than that of BSM and BSM + 5%WTR. When only considering the optimal nitrogen reduction effect, it was necessary to deepen the depth of the submerged area to improve the nitrogen control effect. When considering the optimal control effects of water volume and nitrogen, the thickness of the filler layer was the key factor affecting the water reduction rate. Overall, this study demonstrated that corn straw biochar can effectively improve the regulation effect of bioretention systems, and the optimization of parameters can provide references for the design of bioretention systems.
اظهر المزيد [+] اقل [-]Preparation of Activated Bio-char from Corn Stalk for Color Treatment of Effluent from Packaging Paper Mill النص الكامل
2021
Hoang, Phan Huy | Dat, Nguyen Minh | Thanh, Nguyen Thi
In recent years, the paper industry is developing strongly and plays an important role in the industry of our country. Most of the factories have their own wastewater treatment systems. In general, wastewater in paper mill is very difficult to treat and to handle, especially color (Pt–Co) index. In this research, activated carbon with a high surface area and high adsorption capacity was prepared from corn stalks, an agricultural by-products. The suitable conditions of pyrolysis were investigated to prepare activated bio-char from corn stalk. Then, as-obtained carbon material was applied for color treatment of effluent from paper mill. The activated carbon showed high efficiency and capability in color removal of waste water, with the color reduction of 77%.
اظهر المزيد [+] اقل [-]Assessment of the Effect of Organic Matter on the Retention of Pb+2 in Artificial Soils النص الكامل
2021
Sánchez-Andica, Rubén Albeiro | Chamorro-Rengifo, Andrés Felipe | Páez-Melo, Martha Isabel
Four artificial soils (AS) were prepared based on a mixture of humus, bentonite, kaolinite, and polyvinyl chloride (PVC), as inert matter, in the following proportion: 0%, 12.44%, 37.50%, 78.55% of humus, 10.5% of bentonite, 10.5% of kaolinite, and 78.92%, 66.26%, and 41.46% of PVC. The AS were prepared with variable content of organic matter (OM) in order to evaluate the retention of lead (II) due solely to the content of OM. The results indicated that retention capacity of Pb⁺² increases (19.74 mg/g, 20.89 mg/g, 61.61 mg/g, and 79.48 mg/g) as OM increases (0%, 1%, 5%, and 10%); however, this retention is not proportional to the OM increment. An increase of background solution concentration of 0.01 M to 0.1 M resulted in a 50% decrease in the lead retention capacity. The fitting of lead adsorption was performed by the regression coefficient (R²). All R² of the Langmuir model fit successfully to all types of AS (0.973 for 10-OM, 0.9845 for 5-OM, 0.999 for 1-OM, 0.994 for 0-OM). The adsorption kinetics also fits well to the pseudo-second-order model (R²₁₀₋OM = 0.989, R²₅₋OM = 0.999, R²₁₋OM = 0.999, and R²₀₋OM = 0.999). The thermodynamic values of the Gibbs free energy (ΔG⁰₁₀₋OM = − 10.62, ΔG⁰₅₋OM = − 11.50, ΔG⁰₁₋OM = − 14.23, and ΔG⁰₀₋OM = − 17.06) indicated that it was a spontaneous process, and the energy of the process suggests a retention mechanism by ion exchange. A soil with high content of OM does not guarantee high retention of lead, even more so when the adsorption mechanism is given by ion exchange.
اظهر المزيد [+] اقل [-]Differential Zn and Mn sensitivity of microalgae species from genera Bracteacoccus and Lobosphaera النص الكامل
2021
Maltsev, Yevhen | Maltseva, Anna | Maltseva, Svetlana
One of the most common pollutants in natural ecosystems is heavy metals. Algae are sensitive to the action of heavy metals. This allows to use algae to assess the toxicity of heavy metals, bioindication, and during phycoremediation. This study examines the effect of different Zn and Mn concentrations (1.0, 5.0, 25.0, 50.0, 500.0, 1000.0 mg L⁻¹) on green algae Bracteacoccus minor and Lobosphaera incisa in a chronic bioassay. The results of this study showed that the toxic effect of Zn and Mn on B. minor and L. incisa begins to manifest itself at the lowest of the studied metal concentrations—1 mg L⁻¹. The critical concentration of Zn, which leads to the complete death of B. minor and L. incisa, is 50.0 and 500.0 mg L⁻¹, and Mn is 1000.0 mg L⁻¹ and 500.0 mg L⁻¹, respectively. It was found that principal component (PC) 1 accounts for 60.47% of the total variance and reflects changes associated with low concentrations of heavy metals (up to 5.0 mg L⁻¹). PC2 accounts for 27.95% of the total variance. PC2 is mostly associated with high concentrations of ions of heavy metals. Thus, the effect of Zn and Mn concentrations up to 5 mg L⁻¹and above 50 mg L⁻¹on B. minor and L. incisa has a different character. At the same time, the response of the studied algae species to the action of Zn and Mn has individual differences. In general, B. minor is more resistant to Mn, while L. incisa is more resistant to Zn.
اظهر المزيد [+] اقل [-]Dust and microbial filtration performance of regular and antimicrobial HVAC filters in realistic conditions النص الكامل
2021
Joubert, Aurélie | Abd Ali, Safaa Abd Zaid | Frossard, Miora | Andrès, Yves
Two polypropylene HVAC electret filters: a regular filter and an antimicrobial filter containing zinc pyrithione (ZPT), were compared for filtration performance. The study was conducted over 7 months in realistic conditions with semi-urban outdoor air. Several parameters were monitored over the study period: the average temperature was about 20 °C and relative humidity about 60%, the average inlet concentration of cultivable microorganisms was 50 CFU m⁻³, the average inlet concentration of particles was 10 μg m⁻³, the filter pressure drop increased moderately by about 30 Pa, and the particle collection efficiency of soda fluorescein (median diameter 0.35 μm) decreased in the first half of the study period by about 30% and then stabilized. The microbial concentration on the filters was quantified every 2 months using an innovative methodology based on media coupons in conjunction with microorganism quantification by CFU counting, with 5 culture media favorable to bacteria and/or fungi growth. The microbial concentrations on the filters were between 100 and 2000 CFU cm⁻². The antimicrobial effect of zinc pyrithione was confirmed by the fungi cultivated with DRBC agar: no effects in the level of filter clogging were revealed in the range studied. The high statistical deviation in the results regarding the inhibiting effect of zinc pyrithione on bacteria prevents any conclusion.
اظهر المزيد [+] اقل [-]Rapid and sensitive detection of Karlodinium veneficum by a novel double-nick rolling circle amplification النص الكامل
2021
Liu, Fuguo | Zhang, Chunyun | Zheng, Huiwen | Yang, Yuchen | Zang, Diya | Wang, Yuanyuan | Chen, Guofu
Harmful algal blooms caused by Karlodinium veneficum recently occurred with high incidence, posing a serious threat to the marine ecological environment, public health, and mariculture. It is therefore rather vital to establish a method for rapid detection of K. veneficum. In this study, the D1–D2 region of the large subunit rDNA (LSU rDNA D1–D2) of K. veneficum was cloned and sequenced to design the specific probes and primers. A novel method referred to as double-nick rolling circle amplification (dn-RCA) based on the designed probes and primers was initially established. The optimal reaction conditions for dn-RCA were as follows: probe concentration, 200 pM; ligation temperature, 57 °C; ligation time, 50 min; amplification temperature, 60 °C; and amplification time, 60 min. Furthermore, lateral flow dipstick (LFD) was employed instead of agarose gel electrophoresis to analyze dn-RCA products, which can simplify the detection procedure and reduce the operation time. The sensitivity of dn-RCA-LFD was tested with the genomic DNA, the recombinant plasmid containing the inserted LSU rDNA D1–D2, and the DNA crude extract of K. veneficum. The results showed that the sensitivity of dn-RCA-LFD was 10 times higher than that of conventional PCR; the detection limit of dn-RCA-LFD was 1.1 × 10⁻⁴ ng μL⁻¹ for the genomic DNA, 360 copies μL⁻¹ for the recombinant plasmid, and 5.3 cells mL⁻¹ for DNA crude extract. The results of the cross-reactivity test with 22 control microalgal species showed that the dn-RCA-LFD had high specificity for K. veneficum. The stability of dn-RCA-LFD was tested by mixing the interfering genomic DNA with the target genomic DNA, which can be expected to simulate the natural samples containing different ratios of interfering cells to target cells. The results indicated that the performance of dn-RCA-LFD was immune to the DNA concentration of the interfering species. Finally, the practicability of dn-RCA-LFD was further confirmed by the test with field samples collected from the East China Sea. In conclusion, the established dn-RCA-LFD has advantages of high sensitivity, strong specificity, and stable performance, and is therefore promising for rapid detection of K. veneficum.
اظهر المزيد [+] اقل [-]Spatial and temporal distribution of pollution indices in marine surface sediments—a chemometric approach النص الكامل
2021
Radomirović, Milena | Tanaskovski, Bojan | Pezo, Lato | Ceccotto, Federica | Cantaluppi, Chiara | Onjia, Antonije | Stanković, Slavka
Concentrations of As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn, and Fe measured at forty locations in the Boka Kotorska Bay were used to monitor the spatial and temporal quality of sediment and to assess surface sediment contamination over the last 15 years. This ecological geochemistry assessment was made using two classes of pollution indices: single indices concerning the investigated elements (contamination factor (Cf)) and integrated indices concerning the locations (pollution load index (PLI), potential ecological risk index (RI), mean effects range median quotient (MERMQ), toxic risk index (TRI), contamination severity index (CSI)). The distribution of all indices was geostatistically mapped and several hotspots were identified. Based on the indices applied in the risk assessment, the mean contribution of individual metal species to the total risk was determined and presented in the following order: Cd > Hg > As > Pb > Ni > Cu > Cr > Zn. This study revealed that Cd and Hg were at the top of the risk list among the examined elements. The temporal distribution of Hg has shown a decreasing trend during the period 2005–2019, while the presence of Cd in the Bay environment is of major concern. The results revealed that the most polluted part of the investigated area was Tivat bay within the Boka Kotorska Bay. Multivariate statistical analysis of pollution indices resulted in multicollinearity, which enabled the use of a reduced number of indices with an acceptable risk estimation.
اظهر المزيد [+] اقل [-]ICT, foreign direct investment and environmental pollution in major Asia Pacific countries النص الكامل
2021
Bhujabal, Padmaja | Sethi, Narayan | Padhan, Purna Chandra
This paper examines the effect of ICT and FDI on environmental pollution in major Asia Pacific countries during the year 1990–2018. We use Pooled Mean Group (PMG) and Dumitrescu-Hurlin Panel Causality for the estimation of the results. Our results suggest that ICT and FDI affect the carbon emissions or environmental pollution negatively. This implies that with the rise in ICT infrastructure and FDI inflows, environmental pollution decreases significantly in the long run. The Dumitrescu-Hurlin causality results suggest the existence of bidirectional causality among ICT and FDI which implies that increase in foreign investment leads to increase in ICT infrastructure and also, with increasing ICT infrastructure, the foreign investment increases in the Asia Pacific countries. On the policy forefront, the main focus should be targeted towards promoting FDI and ICT infrastructure in order to facilitate sustainable economic development in the Asia Pacific countries.
اظهر المزيد [+] اقل [-]Cd tolerance and accumulation in barley: screening of 36 North African cultivars on Cd-contaminated soil النص الكامل
2021
Ayachi, Imen | Ghabriche, Rim | Kourouma, Yan | Ben Naceur, M’barek | Abdelly, Chedly | Thomine, Sebastien | Ghnaya, Tahar
In North Africa, barley (Hordeum vulgare L) is the second most cultivated cereal. In Tunisia, barley is cultivated in mining areas with possible Cd soil contamination. The accumulation of Cd was studied in the 36 most cultivated North African barley cultivars cultured during 6 months on control soil and on soil containing 10 ppm of Cd. Cadmium did not affect germination and morphology in any cultivar. However, Cd induced variable effects on the biomass according to the cultivar. The cultivar Lemsi was the most sensitive one and Gisa 127 the most tolerant to Cd. The spike morphology did not show any differences between control and Cd-treated plants. The number of grains per spike and the weight of kernels were differently affected by Cd. On this basis, we identified Manel, Temassine, Giza 130, and Firdaws as the most tolerant cultivars and Raihane, Giza 123, Adrar, and Amira as the most sensitive ones. Cd accumulated at a higher concentration in straw than in the grains, but for both organs, we observed a significant intraspecific variability. In the straw, Lemsi and Massine showed the highest Cd concentration, while the lowest concentration was recorded in Temassine. In the kernels, Amalou showed the highest Cd concentration, 14 μgg⁻¹ of dry weight (DW), but the lowest Cd concentration was 1.7 μg g⁻¹ DW in Kebelli. Based on the official allowable limit of Cd in the grain, all cultivars represent a potential risk when cultivated on soil contaminated with 10 ppm Cd. The molecular and physiological basis responsible for the differences in Cd tolerance and accumulation among barley cultivars will require more investigations.
اظهر المزيد [+] اقل [-]Photosynthetic rate and chlorophyll fluorescence of barley exposed to simulated acid rain النص الكامل
2021
Hu, Hao | Hua, Wei | Shen, Alin | Zhou, Hongkui | Sheng, Li | Lou, Weidong | Zhang, Guangzhi
Acid rain is considered one of the most serious plant abiotic stresses. Photosynthesis is the basis of crop growth and development. The effect of acid rain on barley photosynthesis remains unclear. A glasshouse experiment was conducted, and the photosynthetic rate, chlorophyll (Chl) fluorescence, and pigment content of barley were measured in simulated acid rain (SAR) under pH 6.5, 5.5, 4.5, and 3.5. The results showed that net photosynthetic rate, maximal photosynthetic rate, and light saturation point decreased and the light compensation point, and dark respiration rate increased with increasing acidity. The results suggested that photosynthesis in barley plants was inhibited by SAR stress. The Chl content and stomatal conductance declined in parallel with the reduced net photosynthetic rate when barley plants were under SAR stress conditions. This indicated that non-stomatal factors may contribute to reduced photosynthesis under acid rain stress. Acid rain had greater effects on the photosynthesis of the acid rain-sensitive plant Zhepi 33 than on non-sensitive Kunlun 12. A significant difference in parameters such as the maximal fluorescence, variable fluorescence, and active PSII reaction centers was found among the SAR treatments and may be used to evaluate the sensitivity of plants to acid rain stress. The visualization model showed that the photosynthetic reaction centers were inactivated in acid rain stressed barley plants. These findings are valuable for the evaluation of the plant sensitivity to acid rain stress and may be used for the detection and monitoring of acid rain effects on plants in the future.
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