خيارات البحث
النتائج 2861 - 2870 من 4,936
Assessment of soil buffer capacity on nutrients and pharmaceuticals in nature-based solution applications النص الكامل
2019
Barbagli, Alessio | Jensen, Benjamin Niklas | Raza, Muhammad | Schüth, Christoph | Rossetto, Rudy
The ability of a soil to sustain infiltration rates and to attenuate pollutants is critical for the design and operation of Managed Aquifer Recharge/Soil Aquifer Treatment and phyto-treatment schemes, also referred to as “Blue Infrastructures”. We investigated the buffering capacity of a sediment sample and a peat soil sample for nutrients and selected pharmaceutical compounds and its evolution under continuous infiltration of secondary treated wastewater (TWW) in column experiments. Samples were obtained from two blue infrastructures, the Sant’Alessio Induced River Bank Filtration plant and the San Niccolò large-scale phyto-treatment plant in Italy, and were mainly different in their organic carbon contents (0.9 and 48%, respectively). In the column experiments, a constant infiltration rate of about 0.5 L/d was maintained for 6 months. After 4 months of operation, diclofenac and carbamazepine were spiked into the TWW to evaluate their fate. Water quality was monitored by periodic water sampling from the column inflow, at sampling ports along the column length, and at the outflow. Hydraulic conductivity (K) was also monitored. The hydraulic conductivity of the Sant’Alessio sediment decreased by a factor of 10 during the first 10 days of infiltration and then stabilized, while for the San Niccolò K (initially lower) remained constant for 50 days until it decreased following a change of the redox condition in the column. The different redox conditions, due to the two different soils tested, influenced also the concentration and mobility of PO₄³⁻, Fe, Mn, and NPOC, and the speciation of the redox sensitive elements (nitrogen and sulfur). NOPC and phosphate were enriched during the filtration through San Niccolò peat soil (from 2 to 4 times, respectively), while they were buffered by the Sant’Alessio sediment (from 0.2 to 0.4 times, respectively). Diclofenac removal (69% and below 20% for San Niccolò and Sant’Alessio, respectively) was related to sorption and degradation processes and it was lower than the removal of carbamazepine in both soils (76 and 35%). The buffer capacity differences between the two soils were higher for diclofenac (62%) than carbamazepine (35%). Nevertheless, since no apparent degradation of carbamazepine was detected in both soils, its persistence in the soil may have a larger impact in case of desorption, posing contamination risk to groundwater. The results highlight the importance of the soils or sediments to be used as medium in such nature-based solutions for their operations. They also offer an approach to, e.g., tailor man-made soil layers in infiltration basins. We strongly suggest that soil characteristics and test duration are carefully considered in designing these infrastructures, when nature-based processes are the choice for dealing with reuse of treated wastewater management issues.
اظهر المزيد [+] اقل [-]A novel sorbent for removal of reactive textile dye: TDPA-KCl النص الكامل
2019
Tosun Satır, Ilknur | Sayin, Fatih | Gedikbey, Tevfik | Tunali Akar, Sibel
The use of alunite as an adsorbent for the removal of dye was the aim of this report. Mixing the alunite with different salts may allow adsorption with higher efficiency. In the present study, the thermal decomposition product of alunite-potassium chloride mixture (TDPA-KCl) was used efficiently and inexpensively to remove Reactive Blue 49 (RB49) dye. The adsorption capacity of TDPA-KCl was found to be affected by pH, temperature, adsorbent amount, calcination temperature, dye concentration, and ionic strength. The highest RB49 adsorption yield was obtained at an initial pH of 2 and an equilibrium was reached within 20 min using 80 mg of adsorbent. The most suitable kinetic model was found as the pseudo-second-order and compatible isotherm was determined as the Langmuir model. The optimum adsorption capacity was found as 119.10 mg g⁻¹ at 40 °C. ∆G°, ∆H°, and ∆S° values were calculated. A positive value of ∆H° stated that the adsorption is exothermic and spontaneous. In addition, ∆G° showed a more negative value when temperature was increased. Column studies indicated that TDPA-KCl could be effectively used for five cycles without any loss in its desorption potential. Breakthrough studies also supported a favorable adsorption of RB49 onto TDPA-KCl. This study showed that TDPA-KCl is a practical, efficient, and inexpensive adsorbent to remove reactive dyes from wastewater.
اظهر المزيد [+] اقل [-]Efficient removal of oxytetracycline from aqueous solution by a novel magnetic clay–biochar composite using natural attapulgite and cauliflower leaves النص الكامل
2019
Wang, Zhaowei | Yang, Xing | Qin, Tingting | Liang, Guiwei | Li, Yan | Xie, Xiaoyun
A novel magnetic attapulgite–biochar composite (MABC) derived from natural attapulgite, cauliflower leaves, and FeCl₃ was successfully prepared as a low-cost adsorbent for oxytetracycline (OTC) removal from aqueous solution. Characterization experiments by different techniques suggested that attapulgite clay particles and Fe₃O₄ nanoparticles were successfully covered on the MABC surface. Compared with the pristine biochar (CLB) and attapulgite–biochar composite (ABC), MABC had the largest surface area, well-developed pore structure, and more surface oxygen-containing functional groups which could interact with organic pollutant via hydrogen bonding, π–π electron coupling, complexation, and ion exchange. The maximum adsorption capacity of MABC by the Langmuir model was 33.31 mg/g, which was dramatically higher than that of CLB and ABC. The effects of solution initial pH had little difference on the adsorption of OTC because of the buffering effect. Adsorbent-regeneration studies of MABC exhibited good reusability and separation property. All the results indicated that MABC could be used as a potential adsorbent because of its easy preparation and separation, high efficiency, wide pH range application, and abundant and cheap raw materials in the global ecosystem. Graphical abstract
اظهر المزيد [+] اقل [-]Contamination status and potential release of trace metals in a mangrove forest sediment in Ho Chi Minh City, Vietnam النص الكامل
2019
Dung, Tran Thi Thu | Linh, Tong My | Chau, Tran Bích | Hoàng, Trường Minh | Swennen, Rudy | Cappuyns, Valerie
Can Gio district is located in the coastal area of Ho Chi Minh City, southern Vietnam. Discharge of wastewater from Ho Chi Minh City and neighboring provinces to the rivers of Can Gio has led to concerns about the accumulation of trace metals (As, Cu, Cr, Ni, Pb, and Zn) in the coastal sediments. The main objective of this study was to assess the distribution of As, Cu, Cr, Ni, Pb, and Zn in surface and core sediments and to evaluate the contamination status in relation to local background values, as well as the potential release of these selected trace metals from sediments to the water environment. Sediment characteristization, including determination of fine fraction, pH, organic matter, and major elements (Al, Fe, Ca, K, Mg, and S), was carried out to investigate which parameters affect the trace metal enrichment. Fine fraction and Al contents were found to be the controlling proxies affecting the distribution of trace metals while other sediment characteristics did not show any clear influence on trace metals’ distribution. Although As concentrations in the sediments were much higher compared to its reference value in other areas, the enrichment factor based on local background values suggests minor contamination of this element as well as for Cr, Cu, and Pb. Risk assessment suggested a medium to very high risk of Mn, Zn, and Ni under acidification. Of importance is also that trace metals in sediments were not easily mobilized by organic complexation based on their low extractabilities by ammonium-EDTA extraction.
اظهر المزيد [+] اقل [-]Is foreign direct investment an engine for energy consumption? An empirical investigation for Turkey النص الكامل
2019
Uzar, Umut | Eyuboglu, Kemal
In the study, the nexus among energy consumption, foreign direct investment (FDI), economic growth, and trade openness is examined by newly developed Fourier ADL (2017) and ARDL tests cover the period 1980–2015 in Turkey. Findings indicated that energy consumption, FDI, economic growth, and trade openness are cointegrated. In addition, it is determined that an increase in economic growth and trade openness positively affects energy consumption both in the long-term and short-term but FDI has only a positive effect in the long-term. VECM causality results indicated that FDI, economic growth, and trade openness are the causes of energy consumption in the long-term. In this context, Turkish policymakers should change the composition of FDI through various incentive policies to provide energy efficiency. FDI inflows should be shifted from sectors using dirty technology to clean technologies such as the information technology and services sector. In addition, increasing FDI that included green technology and renewable energy sources may promote energy efficiency in Turkey.
اظهر المزيد [+] اقل [-]Synthetic agrochemicals: a necessary clarification about their use exposure and impact in crop protection النص الكامل
2019
Marchand, Patrice A.
Synthetic pesticides are largely decried. A common attitude against the synthetic agrochemicals is to avoid, criticise or ban these substances. Along with chemical pesticides to defend crops from bioagressors are microorganisms, semiochemical and natural substances used as plant protection products including biocontrol agents (BCAs) and crop protection products in organic production. Nevertheless, a natural substance status does not confer or imply safety, security or absence of residues (in the context of plant protection). Although in this paper we do not consider the toxicological perspective of highly toxic chemicals with adverse effects on humans and non-target organisms sprayed on crops, we have applied ourselves to working on the safe use of synthetic agrochemicals. Thus, along with biopesticides (either BCA or others) allowed in organic farming, we show that some synthetic chemical pesticides may be used in safe manner. HIGHLIGHTS: • Synthetic agrochemicals are widely criticised. • Some pesticide usages are not sprayed on crops. • Some biocontrol agents are of synthetic origin.
اظهر المزيد [+] اقل [-]Exposure to phthalates and bisphenol A is associated with higher risk of cardiometabolic impairment in normal weight children النص الكامل
2019
Mansouri, Vahid | Ebrahimpour, Karim | Poursafa, Parinaz | Riahi, Roya | Shoshtari-Yeganeh, Bahareh | Hystad, Perry | Kelishadi, Roya
Some obese individuals have normal metabolic profile, and some normal-weight persons have impaired metabolic status. Our hypothesis was that one of the potential underlying factors for such differences in cardiometabolic profiles might be the exposure to some environmental chemicals. This study aimed to investigate the association of serum bisphenol A (BPA) and phthalate metabolites with cardiometabolic risk factors in children and adolescents independent of their weight status. This case–control study was conducted on a subsample of 320 participants of a national school-based surveillance program in Iran. We measured serum BPA and phthalate metabolites by gas chromatography mass spectrophotometry. We compared them in children and adolescents with and without excess weight and those with and without cardiometabolic risk factors (80 in each group). We categorized the concentrations of chemicals to tertiles and then we applied logistic regression models after adjustment for potential confounding factors. The concentrations of BPA and some metabolites of phthalates were significantly different in the four groups studied. MEHP concentration was associated with higher odds ratio of cardiometabolic risk factors in participants with normal weight (OR, 95% CI 2.82, 1.001–7.91) and those with excess weight (OR, 95% CI 3.15, 1.27–7.83). MBP concentration increased the odds ratio of cardiometabolic risk factors only in normal weight children and adolescents (OR, 95% CI 6.59, 2.33–18.59, P < 0.001). In participants without cardiometabolic risk factor, MMP and MEHHP were significantly associated with increased risk of excess weight (OR, 95% CI 5.90, 1.21–28.75 and 7.82, 1.5–41.8, respectively). This study showed that the association of BPA and phthalate with cardiometabolic risk factors is independent of the weight status. Our findings suggest that the metabolic impairment in some normal weight children and normal metabolic profile of some obese children can be, in part, related to exposure to these environmental chemicals. Graphical abstract
اظهر المزيد [+] اقل [-]Study of optimal conditions in semi-continuous anaerobic co-digestion of table olive effluents and pig manure in a perfectly stirred reactor النص الكامل
2019
González, Juan F. | Parralejo, Ana I. | Bolívar, Heidi M. | Gonzalez, Jeronimo
Brines from table olive elaboration were co-digested with pig manure, obtaining high methane productions. In particular, the methane yields obtained for pig manure total solid (TS) initial concentrations of 2%, 7%, 9% (wet basis, wt.) were 106, 213 and 247 mL CH₄ gVS⁻¹ₐdd, respectively, using mixtures of two types of brine (acid (A) and basic (B)) generated in the elaboration process. Moreover, an experiment with only basic brine was made, using a pig manure TS concentration of 7% wt. In this case, a methane yield of 224 mL CH₄ gVS⁻¹ₐdd was obtained. The methane production rate was calculated in experiments of 7% pig manure TS concentration and a high kinetic constant of 0.31 d⁻¹ was obtained for the mixture of residual brine. Finally, the effect of Na⁺ cation concentration was evaluated in the mixture A:B during co-digestion processes with a 7% wt. pig manure TS concentration and inhibition was detected in this process with a [Na⁺] of 0.56% wt. of the total sample. An energy and economical study on the treatment of these wastewaters by means of anaerobic co-digestion demonstrated a great economic benefit for the producer industry, a reduction in the diesel consumption used to produce its energetic demand and a reduction cost of 3.63 €/m³ generated of A:B brines mixture with ratio 2:1.
اظهر المزيد [+] اقل [-]Low digestibility of phytate phosphorus, their impacts on the environment, and phytase opportunity in the poultry industry النص الكامل
2019
Abbasi, Farzana | Fakhur-un-Nisa, Tahmina | Liu, Jingbo | Luo, Xuegang | Abbasi, Imtiaz Hussain Raja
Phosphorus is an essential macro-mineral nutrient for poultry, needed for the body growth, development of bones, genomic function, good quality flesh, and eggs production. The imbalance of organic phosphorus sources in the diet mostly affect the phosphorus digestibility, reduces the poultry performance and health, and increases the environmental pollution burden. A study was reviewed to estimate the low phytate phosphorus digestibility of ingredients in poultry diet and their impacts on environmental ecosystem and opportunity of phytase supplementation. Plant ingredients mostly used in poultry diets are rich in phytate phosphorus. The phytate phosphorus digestibility and utilization is low in the gut of birds which leads to decrease other nutrients digestibility and increase excessive excretion of phosphorus with additional nutrients in the manure. When that manure applied to the lands containing excessive residual phosphorus and additional nutrients which pollute soil, groundwater disturbed the entire ecosystem. This issue is developed by poultry due to lack of digestive enzyme phytase which promotes the phytate phosphorus during digestion and reduces the excessive losses of phosphorus in excreta. To overcome this matter, the addition of mostly exogenous phospho-hydrolytic phytase enzymes in the diet, i.e. Escherichia coli, Peniophora lycii, Aspergillus niger, and Ficum, are the possible ways to increase the digestibility and utilization of phytate phosphorus and promote the stepwise release of phosphorus from phytate and significantly decrease phosphorus excretion. The aim of this review is to highlight the role of phytase supplementation in the poultry feeding, improvement of phytate phosphorus digestibility with performance, and reduction of phosphorus pollution from the environment.
اظهر المزيد [+] اقل [-]Occurrence, speciation, and risks of trace metals in soils of greenhouse vegetable production from the vicinity of industrial areas in the Yangtze River Delta, China النص الكامل
2019
Yang, Lanqin | Liu, Guoming | Di, Lin | Wu, Xiangyang | You, Wenhua | Huang, Biao
The effect of industrial activities on trace metals in farmland of rapidly industrializing regions in developing countries has increasingly been a concern to the public. Here, soils were collected from 13 greenhouse vegetable production (GVP) farms or bases near industrial areas in the Yangtze River Delta of China to investigate the occurrence, speciation, and risks of Cr, Cu, Zn, Cd, Ni, and Pb in GVP soil. The results revealed that the main metal elements causing GVP soil pollution were Cd, Zn, Ni, and Cu, of which contamination levels were generally unpolluted to moderately polluted. Zinc pollution was mainly attributed to heavy fertilization, while Cd, Ni, and Cu pollution may be greatly ascribed to industrial effluents and coal combustion. Metal speciation studies showed that most of Cr, Ni, Cu, and Zn was present in residual fraction while more than half of Cd and Pb was present in non-residual fractions. Additionally, pollution of Cd, Cu, Ni, and Zn in GVP soil increased their corresponding mobile fractions. Risk assessment using potential ecological risk index and risk assessment code showed that Cd was the major risk contributor. Specifically, Cd generally posed moderate or considerable ecological risk as well as displayed medium or high mobility risk in GVP soil. Thus, great attention should be paid to the contribution of both industrial discharges and intensive farming to soil pollution by trace metals, especially Cd, because of its high mobility risk.
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