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A new marine sediment certified reference material (CRM) for the determination of persistent organic contaminants: IAEA-459 Texte intégral
2019
Tolosa, Imma | Cassi, Roberto | Huertas, David
A new marine sediment certified reference material (IAEA 459) with very low concentrations (μg kg⁻¹) for a variety of persistent organic contaminants (POPs) listed by the Stockholm Convention, as well as other POPs and priority substances (PSs) listed in many environmental monitoring programs was developed by the IAEA. The sediment material was collected from the Ham River estuary in South Korea, and the assigned final values were derived from robust statistics on the results provided by selected laboratories which demonstrated technical and quality competence, following the guidance given in ISO Guide 35. The robust mean of the laboratory means was assigned as certified values, for those compounds where the assigned value was derived from at least five datasets and its relative expanded uncertainty was less than 40% of the assigned value (most of the values ranging from 8 to 20%). All the datasets were derived from at least two different analytical techniques which have allowed the assignment of certified concentrations for 22 polychlorinated biphenyl (PCB) congeners, 6 organochlorinated (OC) pesticides, 5 polybrominated diphenyl ethers (PBDEs), and 18 polycyclic aromatic hydrocarbon (PAHs). Mass fractions of compounds that did not fulfill the criteria of certification are considered information values, which include 29 PAHs, 11 PCBs, 16 OC pesticides, and 5 PBDEs. The extensive characterization and associated uncertainties at concentration levels close to the marine sediment quality guidelines will make CRM 459 a valuable matrix reference material for use in marine environmental monitoring programs.
Afficher plus [+] Moins [-]Elemental distribution including toxic elements in edible and inedible wild growing mushrooms from South Africa Texte intégral
2019
Rasalanavho, Muvhango | Moodley, Roshila | Jonnalagadda, Sreekantha B.
Macro-elements (Ca, Fe, K, Mg and Na) and trace elements including some toxic (As, Be, Cd, Co, Cu, Mn, Ni, Pb, Se and Zn) were determined in edible and inedible wild-growing mushrooms (Amanita rubescens, Auricularia polytricha, Boletus edulis, Boletus mirabilis, Clavulina cristata, Helvella crispa, Lactarius deliciosus, Suillus luteus, Termitomyces microcarpus, Termitomyces reticulatus, Termitomyces clypeatus, Termitomyces umkowaanii, Amanita foetidissima, Amanita muscaria, Amanita pantherina, Aseroe rubra, Chlorophyllum molybdites, Ganoderma lucidum, Gymnopilus junonius, Hypholoma fasciculare, Lentinus villosus, Lepista caffrorum, Pycnoporus sanguineus, Panaeolus papilionaceus, Pisolithus tinctorius, Pleurotus ostreatus, Podaxis pistillaris, Russula sardonia, Scleroderma citrinum, Scleroderma michiganense). Analyses of samples were carried out using inductively coupled plasma-optical emission spectrometry. The elemental content in both edible and inedible mushrooms, in decreasing order, was found to be K >> Na > Ca > Mg > Fe > Mn > Zn > Cu > Se > Co > Ni > Be > Pb ≥ Cd > As. Our study revealed that the accumulation of metals from the soil is independent of whether mushrooms are edible or inedible as uptake is dependent on the soil quality and its environment. Edible mushroom species studied were found to be rich in Se (145–836% towards the RDA) with B. edulis being rich in it, C. cristata in Cu, S. luteus in Fe and H. crispa in Zn, and all contained low concentrations of toxic metals making them suitable for human consumption.
Afficher plus [+] Moins [-]Fate and toxicity of silver nanoparticles in freshwater from laboratory to realistic environments: a review Texte intégral
2019
Zhang, Weicheng | Ke, Song | Sun, Caiyun | Xu, Xin | Chen, Jibao | Yao, Lunguang
The fate and risk assessment of silver nanoparticles (Ag NPs) is an important environmental health issue. The toxic effects, mechanisms, and modes of action of Ag NPs on aquatic organisms have been extensively determined in the laboratory. However, knowledge gaps and discrepancies exist between laboratory studies and realistic environmental research; such inconsistencies hinder the development of health and safety regulations. To bridge these gaps, this review summarizes how environmental conditions and the physicochemical properties of Ag NPs affect the inconsistent findings between laboratory studies and realistic environmental research. Moreover, this paper systematically reviews different toxic effects of Ag NPs in a realistic environment and compares these effects with those in the laboratory, which is helpful for assessing the environmental fate and risk of Ag NPs. The hazardous effects of Ag NPs on the whole aquatic ecosystem with low concentrations (μg L⁻¹) and long-term periods (months to years) are detailed. Furthermore, two perspectives of future toxicity studies of Ag NPs in realistic freshwater environments are emphasized.
Afficher plus [+] Moins [-]Effect of membrane property and feed water organic matter quality on long-term performance of the gravity-driven membrane filtration process Texte intégral
2019
Lee, Dongwhi | Lee, Yuri | Choi, Shin Sik | Lee, Sang-Ho | Kim, Kyoung-Woong | Lee, Yunho
This study investigated the influence of membrane property and feed water organic matter quality on the permeate flux and water quality during gravity-driven membrane (GDM) filtration. GDM filtration was continuously carried out over 500 days at hydrostatic pressure of 65 mbar in dead-end mode without any back-flushing or membrane cleaning. Three ultrafiltration (UF) membranes (PES-100 kDa, PVDF-120 kDa, and PVDF-100 kDa) and one microfiltration (MF) membrane (PTFE-0.3 μm) were tested for treating lake water with varied organic matter qualities due to algal growth. The fluxes of the four membranes rapidly decreased to ~8 L/(m² × h) within a week of GDM filtration. The flux variations were quite similar for the four membranes during the entire GDM filtration, indicating that membrane property has a little effect on the flux. The flux strongly depends on the feed water organic matter quality. The average flux in treating low organics containing water (7–60 days) was ~5 L/(m² × h) and decreased to ~2 L/(m² × h) in treating high organics containing water (60–300 days). The accumulation of algal-derived biopolymers was mainly responsible for the flux decline by forming biofilms with high permeation resistance. The average flux in 300–500 days increased to ~3.5 L/(m² × h) when the feed water contained lower levels of biopolymers and higher levels of easily biodegradable organics, which created open and heterogeneous biofilms with lower permeation resistance. Removal efficiency for Escherichia coli was more than 5 log, while the removal efficiency for total bacterial cells was 1 log–2 log for the four membranes, indicating some bacterial regrowth after the filtration. Removal efficiency for the MS2 phage was 2.4 log and 1.5 log for the fouled PES-UF and PTFE-MF membranes.
Afficher plus [+] Moins [-]Assessment of soil buffer capacity on nutrients and pharmaceuticals in nature-based solution applications Texte intégral
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.
Afficher plus [+] Moins [-]Membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol- and quinoline-containing wastewater: granular activated carbon vs polyaluminum chloride Texte intégral
2019
Wang, Shun | Ma, Cong | Pang, Chao | Hu, Zhenhu | Wang, Wei
Although anaerobic membrane bioreactor (AnMBR) has been proposed for the treatment of phenolic wastewater, the membrane fouling is still a major obstacle. The effects of dosing of granular activated carbon (GAC) and polyaluminum chloride (PACl) on the treatment performance and membrane fouling of anaerobic ceramic membrane bioreactor were investigated for treating phenol- and quinoline-containing wastewater. The results suggested that the one-off dosing of GAC resulted in a decrease of protein/carbohydrate ratio, which might account for the aggravation of membrane fouling alongside with the decreased flocs size. Nevertheless, the substrate uptake rates (SUR) of phenol and quinoline, and the specific methanogenic activity of sludge at the GAC dosing stage of experimental reactor (R1) were 8.79 ± 0.63 mg phenol g⁻¹ MLVSS d⁻¹, 7.01 ± 0.09 mg quinoline g⁻¹ MLVSS d⁻¹ and 0.27 ± 0.01 g CODCH₄ g⁻¹ MLVSS d⁻¹, which were 1.69, 3.59 and 1.93 times higher than that of the control reactor (R2). The dosing of PACl reduced the membrane fouling rate by changing the floc structure of sludge, as well as the component of SMP and EPS. However, the substrate uptake rate of quinoline was declined. This work provides a comprehensive evaluation on the effect of GAC and PACl dosing on membrane fouling and performance of anaerobic ceramic membrane bioreactor treating phenol-and quinoline-containing wastewater.
Afficher plus [+] Moins [-]Nitrate removal from groundwater using negatively charged nanofiltration membrane Texte intégral
2019
Zou, Lianpei | Zhang, Sitong | Liu, Jianyong | Cao, Yi | Qian, Guangren | Li, Yu-You | Xu, Zhi Ping
A commercial nanofiltration (NF) membrane was modified using poly(sodium 4-styrenesulfonate) (PSS) to improve the nitrate rejection from groundwater. Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential, and water contact angle analyses were performed, showing that PSS was successfully coated onto the membrane with the surface negative charge density being enhanced. The results of nitrate removal tests showed that the best PSS concentration was 1.5 mg/L, with the nitrate rejection rate of 88.8% and the permeate flux of 27.0 L/m² h. The effect of initial nitrate concentration and solution pH on the nitrate removal performance of the modified NF membrane was investigated. The results indicate that the modified NF membrane can improve nitrate removal from actual groundwater, with little membrane permeate flux loss. Graphical abstract
Afficher plus [+] Moins [-]Adsorptive removal of endocrine-disrupting compounds and a pharmaceutical using activated charcoal from aqueous solution: kinetics, equilibrium, and mechanism studies Texte intégral
2019
Zhao, Yufeng | Cho, Chul-Woong | Cui, Longzhe | Wei, Wei | Cai, Junxiong | Wu, Guiping | Yun, Yeoung-Sang
Bisphenol A (BPA), diethyl phthalate (DEP), and carbamazepine (CBZ) have been widely used in chemical and pharmaceutical fields, and their residues are detected in various environments. Therefore, to find a suitable method for removing the compounds from an aqueous solution, an adsorption method by granular activated charcoal (AC) was studied. To investigate the adsorption properties of AC, its kinetics, equilibrium, pH effects, and regeneration of AC were examined. Moreover, its surface properties (i.e., surface area, pore volume, functional groups, and surface charge) were characterized by N₂ adsorption and desorption isotherm, Fourier transform infrared (FTIR), and zeta potential analyses. Experimental results show that AC has high removal efficiencies for the target compounds at the low initial concentration as well as high estimated adsorption capacities (qₘ) for DEP, BPA, and CBZ, whose values were 293.4 ± 18.8, 254.9 ± 16.2, and 153.3 ± 1.61 mg/g, respectively. In comparison with other adsorbents based on previously reported results, AC was shown to have generally higher removability for the three compounds than others. Moreover, it was observed that AC’s ability to adsorb DEP and BPA was dependent on pH because of hydrolysis and ionization, respectively. Meanwhile, there is no pH effect for CBZ adsorption by AC. After 3 cycles of adsorption/desorption, AC still maintained 92, 100, and 82% of initial adsorption capacities for DEP, BPA, and CBZ, respectively. Therefore, the AC is an effective adsorbent for the removal of endocrine-disrupting chemicals and pharmaceuticals from aqueous solution.
Afficher plus [+] Moins [-]Reduction of FeII(EDTA)-NO by Mn powder in wet flue gas denitrification technology: stoichiometry, kinetics, and thermodynamics Texte intégral
2019
Chen, Jun | He, Jinjia | Wang, Xiaoping | Hrynsphan, Dzmitry | Wu, Jiali | Chen, Jianmeng | Yao, Jiachao
Conversion of Feᴵᴵ(EDTA)-NO or Feᴵᴵᴵ(EDTA) into Feᴵᴵ(EDTA) is a key process in a wet flue gas denitrification technology with Feᴵᴵ(EDTA) solution. In this work, the stoichiometry, kinetics, and thermodynamics of Feᴵᴵ(EDTA)-NO reduction by Mn powder were investigated. We first studied the Feᴵᴵ(EDTA)-NO reduction and product distribution to speculate a possible stoichiometry of Feᴵᴵ(EDTA)-NO reduction by Mn powder. Then, the effects of major influencing factors, such as pH value, temperature, and Mn concentration, were studied. The pseudo-second-order model was established to describe the Feᴵᴵ(EDTA)-NO reduction. Simultaneously, according to Arrhenius and Eyring-Polanyi equations, the reaction activation energy (Eₐ), enthalpy of activation (∆H‡), and entropy of activation (∆S‡) were calculated as 23.68 kJ/mol, 21.148 kJ/mol, and − 149.728 J/(k mol), respectively. Additionally, simultaneous reduction of Feᴵᴵᴵ(EDTA) and Feᴵᴵ(EDTA)-NO was investigated to better study the mechanism of Feᴵᴵ(EDTA) regeneration, suggesting that there was a competition between the two reduction processes. Finally, a simple schematic mechanism of NO absorption by Feᴵᴵ(EDTA) combined with regeneration of manganese ion and ammonium was proposed. These fundamental researches could offer a valuable guidance for wet flue gas denitrification technology with Feᴵᴵ(EDTA) solution.
Afficher plus [+] Moins [-]Predicting mercury bioavailability in soil for earthworm Eisenia fetida using the diffusive gradients in thin films technique Texte intégral
2019
Huu Nguyen, Viet | Yee, Seah Kah | Hong, Yongseok | Moon, Deok Hyun | Han, Seunghee
In general, the diffusive gradients in thin films (DGT) technique is an effective tool for evaluating metal bioavailability; however, its applicability is subject to the type of metal and organism involved. In this study, the accumulated masses of Hg in DGT probes and in the earthworm species Eisenia fetida were monitored for 10 days, to test if the DGT technique can be used as a predicting method for the bioavailability of soil Hg to earthworms. In the Hg exposure tests using soils prepared with different peat moss concentrations of 5, 10, 15, and 20% and varying pH values of 4.6, 5.6, and 6.2, the experimentally determined DGT-soil accumulation factor (DSAF) and biota-soil accumulation factor (BSAF) both increased as the peat moss content decreased and the pH increased. According to a one compartment model, this was a result of the increased Hg uptake rate constant (k₁) and the relatively stable Hg elimination constant (k₂) under lower peat moss and higher pH conditions. It is interesting to note that the Hg uptake rates by DGT and earthworms were considerably higher for fresh soils than for aged soils, while porewater (and acid-extractable) Hg concentrations were rather similar between the two types of soils. Across diverse soil properties, steady-state Hg in earthworm tissue showed a strong positive correlation with DGT-measured Hg flux ([earthworm Hg] = 354(DGT−Hg flux)−34, r² = 0.88), while meager correlations were found between Hg concentration in earthworms and that in porewater (and acid-extractable). The overall results indicate that DGT-measured Hg flux is a better tool than conventional methods for predicting Hg bioavailability for earthworms inhabiting diverse types of soil.
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