Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 48.359
Filtrar
1.
Water Sci Technol ; 81(7): 1432-1444, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616695

RESUMEN

In the present study, activated carbon/alginate (AC/ALG) beads were successfully synthesized with different AC:ALG ratios of 1.0-3.0 (w/v) and used for the adsorption of the nonsteroidal anti-inflammatory drug naproxen from wastewater. The beads were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis, and adsorbent dosage, initial pH, initial naproxen concentration, and contact time in removal efficiency were investigated. Maximum naproxen removal percentage was achieved using 350 mg of AC/ALG beads with a ratio of 3.0% (w/v) within six hours and naproxen removal performance was determined to be 98.0%. Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherm models were fitted to the equilibrium data better than the Langmuir model. According to kinetics results, the equilibrium time for the AC/ALG beads was reached in four hours and the kinetic model was determined by the pseudo-second-order equation. The thermodynamic parameters were calculated and enthalpy of naproxen adsorption was found to be positive for all AC/ALG beads. After the adsorption process the beads can easily be regenerated by ethanol and reused within seven cycles.


Asunto(s)
Aguas Residuales , Contaminantes Químicos del Agua/análisis , Adsorción , Alginatos , Carbón Orgánico , Concentración de Iones de Hidrógeno , Cinética , Naproxeno , Espectroscopía Infrarroja por Transformada de Fourier , Termodinámica
2.
Water Sci Technol ; 81(7): 1452-1460, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616697

RESUMEN

In the process of preparing magnetic palygorskite from waste pickling liquor of the steel industry, the dosage of NaOH will affect the properties of the magnetic palygorskite. The experimental results showed that magnetic palygorskite can be effectively prepared when NaOH dosage is between 255 and 330 g/L. Vibration sample magnetometry proved that different NaOH dosages can affect the saturation magnetization of magnetic palygorskite. The catalytic performance of five catalysts synthesized with different NaOH dosages hardly changed after five cycles of Fenton-like catalytic degradation of tetracycline (TC). The magnetic palygorskite prepared by this method had good catalytic performance even when the catalyst preparation conditions were magnified ten times, which can provide a reference for large-scale preparation of magnetic palygorskite.


Asunto(s)
Contaminantes Químicos del Agua/análisis , Compuestos de Magnesio , Fenómenos Magnéticos , Compuestos de Silicona , Hidróxido de Sodio
3.
Water Sci Technol ; 81(7): 1461-1470, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616698

RESUMEN

In this paper, a simple and green method was developed to fabricate a three-dimensional (3D) graphene-based material with the assistance of caffeic acid (CA). The prepared 3D graphene displayed fast and high sorption for norfloxacin (NOR) and ketoprofen (KP). Their adsorption equilibrium was achieved within 12 h for NOR and KP, which was attributed to their fast diffusion in the porous structure of the 3D graphene. The maximum adsorbed amount of this adsorbent was 220.99 mg/g for NOR and 125.37 mg/g for KP according to the Langmuir model at pH 6.6, 298 K. In the competitive adsorption of six pharmaceuticals, the organic compounds in the form of cations are preferentially adsorbed on the adsorbent. The co-existing organic compounds in the actual wastewater do not seriously inhibit the adsorption of NOR and KP. This study provides the theoretical basis for the facile and low-cost preparation of high-performance 3D graphene adsorbents. The results of this study demonstrate the potential utility of 3D graphene as a very effective adsorbent for pharmaceuticals removal from contaminated water.


Asunto(s)
Grafito , Cetoprofeno , Contaminantes Químicos del Agua/análisis , Adsorción , Ácidos Cafeicos , Norfloxacino
4.
Water Sci Technol ; 81(7): 1471-1478, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616699

RESUMEN

SiO2 gel was formed on the grain surface of silica sand by hydrolysis and condensation of tetraethyl orthosilicate in water with the addition of 1-butylamine. The resultant product was a composite consisting of sand grains with mesoporous silica coating containing alkylamine inside. This composite exhibited basicity in the wastewater from copper electroplating due to its release of amine. As a result, the strongly acidic wastewater was neutralized and the co-precipitation of complex metal ions occurred. It was shown that up to 12 major metal ions in the wastewater could be simultaneously removed under static condition at room temperature by using the sand composite. The Fe and Cu in the wastewater could be removed completely, while the concentrations of Al, Cd, Ti, V, and Zn in the wastewater were reduced by two to three orders of magnitude. After the removal of multiple metal ions from the electroplating wastewater, the used sand was further applied as a raw material for making a silicate glass. The glass was chemically stable and thus the heavy metal ions from the wastewater were immobilized.


Asunto(s)
Metales Pesados/análisis , Contaminantes Químicos del Agua/análisis , Cobre , Galvanoplastia , Iones , Arena , Dióxido de Silicio , Aguas Residuales
5.
Water Sci Technol ; 81(7): 1479-1493, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616700

RESUMEN

Finding an appropriate adsorbent with high adsorption capacity, quick adsorption kinetics and easy regeneration was crucial to the removal of gallic acid (GA) from water and wastewater. Our aims were to investigate whether a magnetic ion exchange (MIEX) resin had the three merits mentioned above, and investigate the feasibility of GA adsorption on MIEX resin, and the adsorption kinetics, equilibrium, thermodynamics, regeneration and mechanism using batch tests. The uptake of GA increased with increasing GA concentration. The GA concentration influenced the time needed to reach equilibrium, but the adsorption could be completed within 120 min. Elevating temperature facilitated the GA removal. The removal percent remained above 95.0% at pH 5.0-11.0. Carbonate and bicarbonate promoted the GA removal; conversely chloride, sulfate and nitrate restrained the GA removal significantly. The adsorption kinetics could be fitted well with the pseudo second-order model, and the film diffusion governed the whole adsorption rate. The equilibrium data followed the Redlich-Peterson isotherm model. The adsorption was a spontaneous, endothermic and entropy driven process. The ion exchange dominated the removal mechanism. The spent MIEX resin was well regenerated by sodium chloride. Therefore, MIEX resin is a potential adsorbent for removing GA quickly and efficiently from water and wastewater.


Asunto(s)
Ácido Gálico , Contaminantes Químicos del Agua/análisis , Adsorción , Concentración de Iones de Hidrógeno , Resinas de Intercambio Iónico , Cinética , Fenómenos Magnéticos , Soluciones , Temperatura , Termodinámica
6.
Water Sci Technol ; 81(7): 1518-1529, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32616703

RESUMEN

Despite the fact of natural abundance, low cost and environmental friendliness, the far-from-sufficient adsorption capacity of natural bentonite (BT) has limited such a promising application to remove dye pollutants. In this paper, we proposed a facile modification strategy to enhance adsorption performance of bentonite utilizing synergistic acid activation and hydroxyl iron pillaring, by which the adsorbent (abbreviated as S-Fe-BT) exhibited the highest adsorption capacity (246.06 mg/g) and a high rapid adsorption rate for a typical organic dye, Rhodamine B (RhB). This could be ascribed to the increased interlayer spacing, the increased specific surface area, and the optimized OH/Fe ratio after the synthetic modification of the pristine BT. The adsorption behavior of RhB onto S-Fe-BT was well described by the pseudo-second-order kinetic model, indicating a chemical-adsorption-controlled process. Furthermore, its adsorption isotherm matched well with the Langmuir model due to a monolayer adsorption process. This paper opens a promising direction to remove the dye pollution using low cost bentonite adsorbents treated by such a convenient modification strategy.


Asunto(s)
Bentonita , Contaminantes Químicos del Agua/análisis , Adsorción , Concentración de Iones de Hidrógeno , Hierro , Cinética , Termodinámica
7.
Environ Monit Assess ; 192(7): 473, 2020 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-32607767

RESUMEN

Electrochemical advanced oxidation process (EAOP) is known for its efficient and fast degradation of organic pollutants in polluted water treatment. In this study, the EAOP using a boron-doped diamond (BDD) anode was applied to treat two-season groundwater samples collected from four sampling wells (GS1 to GS4) with petrochemical contaminants including methyl tert-butyl ether (MTBE), benzene, toluene, chlorobenzene, total organic compounds (TOC), and total petroleum hydrocarbons (TPH) at a gas station in southern Taiwan. Moreover, toxicity tests (ATP, p53, and NF-κB bioassays) were performed to evaluate the biological responses of raw and EAOP-treated groundwater. Results show that the concentrations of chlorobenzene before and after EAOP treatment were all below its method detection limit. High degradation efficiencies were observed for MTBE (100%), benzene (100%), toluene (100%, except that of GS2 in the first season), TPH (94-97%, except that of GS4 in the first season), and TOC (85-99%). Cell viability for both the raw groundwater (81.2 ± 13.5%) and EAOP-treated samples (84.7 ± 11.7%) as detected using the ATP bioassay showed no significant difference (p = 0.715). A mean reduction in the DNA damage (739 to 165 ng DOX-equivalency L-1 (ng DOX-EQ. L-1)) and inflammatory response levels (460 to 157 ng TNFα-equivalency L-1 (ng TNFα-EQ. L-1)) were observed for EAOP-treated samples subjected to p53 and NF-κB bioassays. Overall, the significances of the average degradation efficiency, DNA damage, and inflammatory response before and after groundwater with EAOP treatment was observed to be significant (p < 0.05). p53 and NF-κB bioassays might be applied to assess ecotoxic risk in the environment.


Asunto(s)
Monitoreo del Ambiente , Agua Subterránea , Contaminantes Químicos del Agua , Agua Subterránea/química , Oxidación-Reducción , Contaminación por Petróleo/análisis , Taiwán , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad , Purificación del Agua
8.
Environ Monit Assess ; 192(7): 417, 2020 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-32506388

RESUMEN

This study assessed the spatial and temporal nutrient variability in the El Fuerte River basin in northwestern Mexico, considering its effects on the water trophic status as well as the nutrient loading to the Gulf of California. Physicochemical parameters, inorganic species of nitrogen, phosphate, total nitrogen, total phosphorus, and chlorophyll-a (chl-a) were quantified at 16 selected sites along the river in April (dry season) and October (rainy season) 2017. Mean concentrations of nutrients during dry and rainy seasons were 36.3 ± 24.1 and 55.1 ± 74.6 µg L-1 of total ammonia nitrogen, 3.4 ± 3.6 and 4.5 ± 3.5 µg L-1 of NO2--N, 190.8 ± 256.0 and 163.6 ± 261.0 µg L-1 of NO3--N, 42.4 ± 44.2 and 104.9 ± 76.2 µg L-1 of PO43--P, 1.0 ± 1.3 and 691 ± 2242 mg L-1 of TN, 0.06 ± 0.06 and 0.08 ± 0.09 mg L-1 of TP, and 0.9 ± 0.6 and 2.0 ± 0.9 µg L-1 of chl-a with significant differences (p < 0.05) between sites and seasons. When waters are transported downstream, nutrient levels are enriched by 4 to 35 times compared to those upstream due to increased population and agriculture downstream, confirming the hypothesis of the study. The calculated TN and TP fluxes were 1.23 × 104 and 3.57 × 101 ton year-1, respectively. Factor analysis indicated that inorganic nitrogen species and phosphorus are the main factors affecting the river water quality. Despite N excess during the rainy season, the river reached mesotrophic waters due to phosphorus limitation. This suggests the need to establish a water quality monitoring program to understand the vulnerability of the river course to changes in its trophic state.


Asunto(s)
Monitoreo del Ambiente , Nitrógeno , Fósforo , Ríos , Contaminantes Químicos del Agua , Clorofila/análisis , México , Nitrógeno/análisis , Nutrientes/análisis , Fósforo/análisis , Ríos/química , Estaciones del Año , Contaminantes Químicos del Agua/análisis
9.
Environ Monit Assess ; 192(7): 421, 2020 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-32514793

RESUMEN

Due to unevenly distributed water resources, semi-arid regions are particularly prone to severe water shortage and quality degradation. In this study, based on long-term hydrological database (1935-2015), and the latest available water quality data sets (2011-2016), we analyzed the water crisis and its driving forces in the upper Yongding River watershed, a typical water shortage area in North China. The results showed that human induced excessive water consumption is responsible for the significantly decreased river flow over the past eight decades. Although the capacity of the watershed wastewater treatment has improved, current water quality does not meet the requirements of the national water management goals, because of the excessive nitrogen and CODCr (chemical oxygen demand), which mainly come from the wastewater and feedlots discharge. Due to the decreased river flow, current Yongding River is unable to dilute and assimilate pollutions. The analysis of river pollutant load illustrated that more than 60 % of the nitrogen in the river water system is diverted for reservoir storage, and more than 50 % of the CODCr and TP are diverted for irrigation, thereby, increasing the risk of reservoirs eutrophication and threatening food safety. Besides, the high Cl- (388.2 ± 322.5 mg/L) and SO42- (470.6 ± 357.7 mg/L) imply that the upper river water are not suitable for drinking and irrigation purposes, and a potential risk of salinization if the river flow continues to decrease. We conclude that water resources over extraction and quality degradation are the main driving factors of the Yongding River water crisis.


Asunto(s)
Monitoreo del Ambiente , Ríos , Contaminantes Químicos del Agua , Calidad del Agua , China , Humanos , Nitrógeno/análisis , Movimientos del Agua , Contaminantes Químicos del Agua/análisis , Calidad del Agua/normas
10.
Environ Monit Assess ; 192(7): 422, 2020 Jun 09.
Artículo en Inglés | MEDLINE | ID: mdl-32519186

RESUMEN

Chlorine dioxide has been reported as very efficiently removing pesticides and other organic compounds from water matrixes. Due to pesticide toxicity and potential toxicity of their degradation products, it is important to monitor these compounds as environmental pollutants in ground and surface waters. Evaluating the effects of chlorine dioxide treatment is necessary, and toxicity studies are used to ascertain the severity of effects of intermediates due to incomplete degradation of the parent compounds. In this paper, for the first time, chlorine dioxide is applied and evaluated for the removal of chloroacetamide herbicides (pethoxamid and metazachlor) from waters (deionized water and Sava River water). The degradation degree of herbicides was measured by high-performance liquid chromatography, the main degradation products were identified using gas chromatography with a triple quadrupole mass detector, and the degree of mineralization was monitored by total organic carbon analysis. Four and two degradation products were identified after pethoxamid and metazachlor degradation, respectively. Total organic carbon analysis showed mineralization occurred, but it was incomplete. The mineralization and the characteristics of the degradation products obtained were tested using Daphnia magna and showed lower toxicity than the parent herbicides. The advantage of the applied treatment was a very high degradation percentage for pethoxamid removal from deionized water and Sava River water (100% and 97%, respectively), with higher mineralization efficiency (65%) than metazachlor. Slightly lower degradation efficiency in the Sava River water was due to chlorine dioxide oxidizing the herbicides and dissolved organic matter simultaneously.


Asunto(s)
Acetamidas , Compuestos de Cloro , Óxidos , Contaminantes Químicos del Agua , Purificación del Agua , Acetamidas/análisis , Acetamidas/química , Acetamidas/metabolismo , Acetamidas/toxicidad , Animales , Compuestos de Cloro/química , Daphnia/efectos de los fármacos , Ecotoxicología , Óxidos/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/metabolismo , Contaminantes Químicos del Agua/toxicidad , Purificación del Agua/métodos
11.
Chemosphere ; 256: 127039, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32559886

RESUMEN

Microplastics (MPs) pollution in the marine has become a global concern. To obtain accurate measurements of MPs in the marine sediments is important for understanding its effects and potential risks to the environment. In this study, we developed a novel method for extracting MPs from sediments by density flotation of sodium dihydrogen phosphate (NaH2PO4) solution, which utilized the heating-assisted to increase the density of separation solution. It features high density, nontoxic, and economic, indicating its promising application in the MPs extraction. A standard procedure based on NaH2PO4 for extracting MPs from sediments was established and validated by the recovery experiments of seven common plastics. Results showed NaH2PO4 solution exhibited higher recovery rates than the commonly-used NaCl solution; three plastics with high density couldn't be recovered by NaCl, while NaH2PO4 was available for all the studied MPs. A large number of real beach samples was collected and validated by this method, and the abundance and characteristic of the collected MPs were further analyzed. Results exhibited the heating-assisted NaH2PO4 could be a promising way for extracting MPs in environmental samples.


Asunto(s)
Monitoreo del Ambiente/métodos , Microplásticos/análisis , Contaminantes Químicos del Agua/análisis , Sedimentos Geológicos/química , Calefacción , Plásticos
12.
Chemosphere ; 256: 127094, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32559888

RESUMEN

Sulfite-based photocatalysis has been recently employed as a promising technology for the treatment of organic pollutants via the generation of reactive radicals. In this contribution, the effect of wastewater matrix constituents and toxicity evaluation were systematically investigated in the FeIII impregnated N-doped TiO2 (FeN-TiO2)/sulfite/visible LED (Vis LED) process in the presence of diphenamid (DPA) as a model organic pollutant. The results showed that the presence of HCO3-, SO42-, NO3-, and F- had no detrimental effect on DPA degradation. Conversely, the presence of Cr(VI), NO2-, Cl-, and Br- caused a stronger retardation effect. The effect of natural organic matter such as humic acid (HA) was inert at normal concentrations. Interestingly, the retardation effect of inorganic ions can be quantified at any given ion concentration based on the linear correlations between the DPA decay (first-order kinetic constants) and concentration of ion species. Toxicity tests on Synechocystis sp., Microcystis flos-aquae, and Nostoc sp. algae revealed that higher toxicity was noticed at 240 min treatment time accompanied by lower toxicity with prolonging the treatment time for all selected algae except for Microcystis flos-aquae. In addition, novel two-phase mathematical models were successfully proposed to predict the accumulation of intermediates depending on their evolution profile.


Asunto(s)
Ácidos Difenilacéticos/química , Contaminantes Químicos del Agua/química , Ácidos Difenilacéticos/toxicidad , Compuestos Férricos , Sustancias Húmicas , Cinética , Microcystis , Fotólisis , Sulfitos , Titanio , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad
13.
Chemosphere ; 248: 125754, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32422855

RESUMEN

Nitrates are bioavailable compounds, which are necessary for every living organisms. However, their excess could be harmful, because it could lead to, i.e., methemoglobinemia, formation of carcinogenic nitrosamines and reservoir eutrophication. Isotopic analysis of δ15N and δ18O in nitrates allows to distinguish their different sources. To simplify the way of nitrate source monitoring, we developed a less complex and cheap "off-line" method for nitrate isotopic analysis, in which we obtain both gases required for isotopic analysis of NO3-, N2 for δ15N and CO2 for δ18O measurements, in one procedure. The developed method is based on simultaneous conversion of AgNO3 (mixed with C and placed into PtIr boat) to N2 and CO2 in a glass vacuum apparatus. A small amount of sample (8 mg of AgNO3) required for this procedure and a good reproducibility of the isotopic analysis (better than 0.3‰ for δ18O and 1‰ for δ15N) make this method a useful tool for environmental research. Using the developed method, we analyzed the isotopic composition of N and O in nitrates in the Zemborzycki Reservoir near Lublin (Poland), in 2015. The results indicate a large variation of δ15N (from -1.4 to +37.7‰) and δ18O (from +5.5 to +25.9‰) values in NO3- ions, while the concentration of NO3- varied from 0.2 to 15.3 mg/dm3. These preliminary results suggest that nitrate fertilizers probably are the main source of NO3- pollution. Our study points out the input of manure and/or sewage to the analyzed reservoir in the subsequent periods of sample collection.


Asunto(s)
Dióxido de Carbono/análisis , Monitoreo del Ambiente/métodos , Nitratos/análisis , Nitrógeno/análisis , Contaminantes Químicos del Agua/análisis , Eutrofización , Fertilizantes/análisis , Estiércol/análisis , Isótopos de Nitrógeno/análisis , Isótopos de Oxígeno/análisis , Polonia , Reproducibilidad de los Resultados , Aguas del Alcantarillado/análisis , Aguas Residuales/análisis , Agua/análisis
14.
Chemosphere ; 251: 126674, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32359720

RESUMEN

Dimensionally stable anodes (DSA) have been widely used to degrade organic compounds because these surfaces promote the electrogeneration of active chlorine species in the bulk of the solution, as well as in the vicinity of the anode when NaCl is used as supporting electrolyte. In this work, the nanoparticles synthesis of IrO2 and RuO2 was performed to obtain two types of DSA electrodes named Class I and II to degrade oxamic acid. For Class I and II DSA, the nanoparticles used were synthesized separately and in the same reaction medium, respectively. Electrolysis were carried out in an open cylindrical cell without division at 25 °C, DSAs were used as anodes and a stainless-steel electrode as cathode, both elements have a geometric area of 2.8 cm2 immersed in 0.05 mol L-1 of NaCl or Na2SO4 and a current density of 3 mA cm-2 was applied for 6 h. Active chlorine species generated in the absence of oxamic acid in NaCl were also detected and quantified through ion chromatography. In Na2SO4 there was no degradation of the compound, but in NaCl the oxamic acid concentration reaching 85% with Class I DSA. The same tendency is observed in mineralization, in which Class I DSA allowed reaching a CO2 transformation close to 73%. The difference in the results occurs because with Class I DSA, more hypochlorite is generated than with Class II and therefore there is a larger amount of oxidizing species in the solution that enables the degradation and mineralization of oxamic acid.


Asunto(s)
Iridio/química , Modelos Químicos , Ácido Oxámico/química , Compuestos de Rutenio/química , Cloro/análisis , Electrodos , Electrólisis/métodos , Nanopartículas , Oxidación-Reducción , Contaminantes Químicos del Agua/análisis
15.
Chemosphere ; 251: 126452, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32443227

RESUMEN

Microplastics (MPs) are prevalent global pollutants that are being detected in aquatic ecosystems and drinking water sources around the world. In addition to plastic polymers, MPs contain various chemical substances (known as "additives") that can leach and risk water quality. In this paper, we investigated for the first time the potential release of disinfection byproducts (DBPs) precursors when MPs are exposed to hydrolysis and/or degradation by simulated sunlight. Seventeen MPs with seven different polymer types were collected either as commercial products (e.g. drinking water bottles, shopping bags, recycled plastics, etc.) or pure/virgin polymers. Results showed high release of dissolved organic carbon (DOC) from five MP samples and a significant increase in bromide concentrations from four MPs. DBPs formation potential (DBPFP) experiments with MPs' leachates showed higher concentrations of chlorinated trihalomethanes (THMs), haloacetonitriles (HANs), and total organic halogens (TOX) in three samples, while a significant shift to brominated DBPs was observed in samples containing bromide. Extending the leaching experiments to four consecutive cycles showed that the leaching of DOC and DBPs' precursor significantly decreased after the second leaching cycle. Further analysis revealed that the reactivity of the leached DOC - indicated by THMFP yields - was comparable to those of several raw waters that supply drinking water treatment plants. The leached THMs and TOX from MPs that were exposed to UVA irradiation were in general higher than MPs that were run under dark conditions.


Asunto(s)
Monitoreo del Ambiente , Microplásticos/análisis , Contaminantes Químicos del Agua/análisis , Bromuros/análisis , Desinfectantes/química , Desinfección , Agua Potable/análisis , Ecosistema , Halogenación , Halógenos/análisis , Plásticos , Trihalometanos/análisis , Calidad del Agua
16.
Chemosphere ; 251: 126414, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32443252

RESUMEN

The disposal of municipal solid waste (MSW) in landfills generates leachate, a highly polluting liquid to the aquatic environment. Leachate composition become a challenge to choose the best treatment process. Then, detailed techniques to determine the organic content, in terms of refractability, composition, sources and biodegradability in landfill leachate can help to choose the appropriate treatment and improve landfill management. In this sense, the aim of this study is to apply conventional and non-conventional parameters through inert chemical oxygen demand (COD) analyses and spectroscopic techniques of fluorescence and UV-vis absorbance for the characterization of municipal landfill leachate. Results indicated that physicochemical characterization cannot provided enough detailed information about leachate composition, which becomes the treatment process fragile. Inert COD, besides have high time to execution (∼30 days), presented additional information on potential of biological treatability in anaerobic conditions. Dissolved organic matter (DOM) characterization showed transitions between labile and refractory organic matter compounds. Moreover, the cost estimated showed that non-conventional parameters analysis have lower investment than conventional, being their implementation feasible. In conclusion, the synergy between conventional and non-conventional parameters, and the detailed information provided by inert COD and DOM characterization, shown a useful tool to the landfill management and, consequently, improving treatment process and its efficiency.


Asunto(s)
Biodegradación Ambiental , Contaminantes Químicos del Agua/análisis , Compuestos Orgánicos , Eliminación de Residuos/métodos , Residuos Sólidos/análisis , Instalaciones de Eliminación de Residuos
17.
Sci Total Environ ; 729: 138770, 2020 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-32361434

RESUMEN

Cardiovascular drugs and lipid regulating agents have emerged as major groups of environmental contaminants over the past decades. However, knowledge about their occurrence in freshwaters and their ecotoxicity is still limited. Here, we critically summarize the presence of 82 cardiovascular drugs and lipid regulating agents at a global-scale and represent their effects on aquatic organisms. Only about 71% of these pharmaceuticals in use have been analyzed for their residues in aquatic ecosystems and only about 24% for their effects. When detected in surface waters, they occurred at concentrations of dozens to hundreds of ng/L. In wastewaters, they reached up to several µg/L. Effects of cardiovascular drugs and lipid regulating agents have been extensively studied in fish and a few in invertebrates, such as Daphnia magna and mussels. These pharmaceuticals affect cardiac physiology, lipid metabolism, growth and reproduction. Besides, effects on spermatogenesis and neurobehavior are observed. Environmental risks are associated with beta-blockers propranolol, metoprolol, and lipid lowering agents bezafibrate and atorvastatin, where adverse effects (biochemical and transcriptional) occurred partially at surface water concentrations. In some cases, reproductive effects occurred at environmentally relevant concentrations. This review summarizes the state of the art on the occurrence of cardiovascular drugs and lipid regulating agents at a global-scale and highlights their risks to fish. Further research is needed to include more subtle changes on heart function and to explore non-investigated drugs. Their occurrence in freshwaters and impact on a diverse array of aquatic organisms are particularly needed to fully assess their environmental hazards and risks.


Asunto(s)
Contaminantes Químicos del Agua/análisis , Animales , Fármacos Cardiovasculares , Ecosistema , Reguladores del Metabolismo de Lípidos , Lípidos , Medición de Riesgo
18.
Chemosphere ; 254: 126836, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32361541

RESUMEN

For oil spilled at sea, the main weathering processes are evaporation, emulsification, photo-oxidation, dispersion and biodegradation. Of these, only biodegradation may completely remove hydrocarbons from the environment in the long term, as the other processes only serve to transform and dilute the oil components. As petroleum development is moving north, the probability of Arctic oil spills increases. Hence, it is imperative to develop methods for comprehensive risk assessment of oil spills in cold and ice-covered waters. Accurate biodegradation rates are an essential part of this, as they are required to predict the long-term effects of marine oil spills. In this paper, we present experimentally determined biodegradation rates for the component groups which are used to represent oil in the OSCAR oil spill model. The experiments have been carried out at seawater temperatures of -2∘C, 0∘C, 5∘C, and 13∘C. We show that for the lighter and more soluble oil components, the changes in degradation rates between 0∘C and 13∘C are well captured by a constant Q10 scaling law. At lower temperatures, and for heavier and less soluble components, the rates are not well described by a constant Q10, probably indicating that oil properties become important for the biodegradation rate.


Asunto(s)
Biodegradación Ambiental , Modelos Químicos , Petróleo , Contaminantes Químicos del Agua/química , Regiones Árticas , Frío , Hidrocarburos/metabolismo , Cubierta de Hielo , Contaminación por Petróleo , Agua de Mar , Temperatura , Contaminantes Químicos del Agua/análisis
19.
Chemosphere ; 255: 126847, 2020 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-32417509

RESUMEN

In this study, surface sediments along the Zayandehrud River (14 samples), and two dated core sediments (46 samples) from small artificial urban lakes at the middle section of the Zayandehrud River in the Gavkhooni basin in the central arid regions of Iran were analyzed for residual levels of 20 organochlorine pesticide (OCP) compounds. Total OCP concentrations ranged from 0.1 to 50.1 ng g-1 dry weight and from 1.9 to 51.5 ng g-1 dry weight in surface and core sediments, respectively. Dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) were found to be the predominant OCPs in these sediments. The calculated metabolic and isomeric ratios confirmed the aged nature of residual dichlorodiphenyltrichloroethane (DDT) in sediments. Moreover, the isomeric ratios indicated the aged nature of technical HCH (hexachlorocyclohexane), while the contribution of γ- HCH (lindane) as a main source has increased, especially in the last two decades. Past usage, as well as current usage of endosulfan technical mixture in the Gavkhooni basin, has been found in the last four decades. Analyses of sedimentary cores, as natural archives, have shown the successful ban on the use of organochlorine pesticides (especially DDT) in the Gavkhooni basin, and to some extent, in the central plateau of Iran. In general, it can be concluded that natural factors (i.e., floods and wet years) lead to soil leachate and play an essential role in remobilization and transfer of residual OCPs from soil to inland aquatic ecosystems in the Gavkhooni basin, which is an arid region.


Asunto(s)
Monitoreo del Ambiente , Hidrocarburos Clorados/análisis , Plaguicidas/análisis , Contaminantes Químicos del Agua/análisis , China , DDT/análisis , Diclorodifenil Dicloroetileno/análisis , Ecosistema , Endosulfano/análisis , Sedimentos Geológicos/análisis , Hexaclorociclohexano , Irán , Lagos/análisis , Ríos , Suelo
20.
Chemosphere ; 252: 126611, 2020 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32443275

RESUMEN

Halogenated disinfection byproducts (DBPs) are formed during chlorine disinfection of drinking water. The complicated natural organic matter in source water causes the formation of an even more complicated mixture of DBPs. To evaluate the toxicity of a DBP mixture in a disinfected water sample, the sample needs to be pretreated in order to attain an observable acute adverse effect in the toxicity test. During sample pretreatment, volatile DBPs including trihalomethanes, haloacetonitriles and haloketones may be lost, which could affect the toxicity evaluation of the DBP mixture. In this study, we intentionally prepared "concentrated" simulated drinking water samples, which contained sufficiently high levels of volatile and nonvolatile DBPs and thus enabled directly evaluating the toxicity of the DBP mixtures without sample pretreatment. Specifically, the natural organic matter and bromide concentrations and the chlorine dose in the concentrated water samples were 250 times higher than those in a typical drinking water sample. Each concentrated water sample was divided into two aliquots, and one of them was nitrogen sparged to eliminate volatile DBPs; then, both aliquots were used directly in a well-established developmental toxicity test. No significant difference (p > 0.10) was found between the developmental toxicity indexes of each concentrated water sample without and with nitrogen sparging, indicating that the contribution of volatile DBPs to the developmental toxicity of the DBP mixture might be marginal. A reasonable interpretation is that nonvolatile halogenated DBPs (especially the aromatic ones) in the DBP mixture could be the major developmental toxicity contributor that warrants more attention.


Asunto(s)
Desinfectantes/toxicidad , Agua Potable/química , Contaminantes Químicos del Agua/toxicidad , Animales , Bromuros , Cloro , Desinfectantes/análisis , Desinfección , Halogenación , Nitrógeno , Poliquetos/fisiología , Trihalometanos/análisis , Contaminantes Químicos del Agua/análisis , Purificación del Agua
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA