scholarly journals Sorption and transformation of the reactive tracers resazurin and resorufin in natural river sediments

2013 ◽  
Vol 10 (10) ◽  
pp. 12187-12216 ◽  
Author(s):  
D. Lemke ◽  
R. González-Pinzón ◽  
Z. Liao ◽  
T. Wöhling ◽  
K. Osenbrück ◽  
...  
Keyword(s):  
River Sediments ◽  
Tracer Tests ◽  
Sorption Isotherms ◽  
Hyporheic Exchange ◽  
Batch Experiments ◽  
Linear Sorption ◽  
Alkaline Conditions ◽  
Kinetic Sorption ◽  
Reactive Tracers ◽  
Transient Tracer

Abstract. Resazurin (Raz) and its reaction product resorufin (Rru) have increasingly been used as reactive tracers to quantify metabolic activity and hyporheic exchange in streams. Previous works have indicated that these compounds undergo sorption in stream sediments. We present a series of laboratory column and batch experiments on Raz and Rru transport, sorption, and transformation within sediments with different physicochemical properties under neutral and alkaline conditions. The data of the column experiments were fitted by a model accounting for physical transport, equilibrium and kinetic sorption, and three first-order reactions. The most likely parameters and their uncertainty were determined by a Markov-Chain Monte Carlo approach. Linear and non-linear sorption isotherms of both compounds were obtained by batch experiments. We found that kinetic sorption dominates sorption of both Raz and Rru, with characteristic timescales of sorption in the order of > 80 min. The linear sorption models for both Raz and Rru appeared adequate for concentrations that are typically applied in field-tracer tests. The supposed two-site sorption model helps interpreting transient tracer tests using the Raz–Rru system.

scholarly journals Sorption and transformation of the reactive tracers resazurin and resorufin in natural river sediments

2014 ◽  
Vol 18 (8) ◽  
pp. 3151-3163 ◽  
Author(s):  
D. Lemke ◽  
R. González-Pinzón ◽  
Z. Liao ◽  
T. Wöhling ◽  
K. Osenbrück ◽  
...  
Keyword(s):  
Travel Time ◽  
Reactive Transport ◽  
Transfer Functions ◽  
Transport Model ◽  
River Sediments ◽  
Tracer Tests ◽  
Hyporheic Exchange ◽  
Transport Parameters ◽  
Kinetic Sorption ◽  
Reactive Tracers

Abstract. Resazurin (Raz) and its reaction product resorufin (Rru) have increasingly been used as reactive tracers to quantify metabolic activity and hyporheic exchange in streams. Previous work has indicated that these compounds undergo sorption in stream sediments. We present laboratory experiments on Raz and Rru transport, sorption, and transformation, consisting of 4 column and 72 batch tests using 2 sediments with different physicochemical properties under neutral (pH = 7) and alkaline (pH = 9) conditions. The study aimed at identifying the key processes of reactive transport of Raz and Rru in streambed sediments and the experimental setup best suited for their determination. Data from column experiments were simulated by a travel-time-based model accounting for physical transport, equilibrium and kinetic sorption, and three first-order reactions. We derived the travel-time distributions directly from the breakthrough curve (BTC) of the conservative tracer, fluorescein, rather than from fitting an advective-dispersive transport model, and inferred from those distributions the transfer functions of Raz and Rru, which provided conclusive approximations of the measured BTCs. The most likely reactive transport parameters and their uncertainty were determined by a Markov chain–Monte Carlo approach. Sorption isotherms of both compounds were obtained from batch experiments. We found that kinetic sorption dominates sorption of both Raz and Rru, with characteristic timescales of sorption in the order of 12 to 298 min. Linear sorption models for both Raz and Rru appeared adequate for concentrations that are typically applied in field tracer tests. The proposed two-site sorption model helps to interpret transient tracer tests using the Raz–Rru system.

scholarly journals Homemade bone charcoal adsorbent for defluoridation of groundwater in Thailand

2010 ◽  
Vol 8 (4) ◽  
pp. 826-836 ◽  
Author(s):  
Sunisa Smittakorn ◽  
Nithat Jirawongboonrod ◽  
Surat Mongkolnchai-arunya ◽  
Deanna Durnford
Keyword(s):  
Sorption Isotherms ◽  
Bone Char ◽  
Batch Experiments ◽  
First Order ◽  
Social Resistance ◽  
Bone Charcoal ◽  
The Social ◽  
The World ◽  
Fresh Bone ◽  
Sorption Characteristics

High levels of fluoride in groundwater are a significant environmental and health problem in Thailand, as in many parts of the world. Small household defluoridators have several advantages over centralized treatment systems. In Thailand, however, use of bone char for water treatment has met resistance because of objectionable taste and odours of the water produced and the social resistance to handling fresh bone. This paper presents a method that uses bone charcoal as an absorbent for removing fluoride from groundwater. The commercially provided boiled bone is burned in a simple homemade furnace that can be constructed, operated and maintained easily by small rural householders. The method to produce the Thai bone char eliminates the odour and objectionable taste and also does not require the user to handle fresh bone, thus eliminating the social resistance. To evaluate the efficacy of the absorbent, batch experiments compare Thai and Indian bone char. Sorption isotherms are fit to the Freundlich and Langmuir equations and the kinetics are modelled using the pseudo first-order Lagergren equation. Results show that the sorption characteristics of Thai bone char compare favourably with the Indian bone char, with approximately 80% of the fluoride removed in both cases.

scholarly journals Occurence of microplastics in the hyporheic zone of rivers

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. Frei ◽  
S. Piehl ◽  
B. S. Gilfedder ◽  
M. G. J. Löder ◽  
J. Krutzke ◽  
...  
Keyword(s):  
Drinking Water ◽  
Food Webs ◽  
Hyporheic Zone ◽  
River Sediments ◽  
Size Fraction ◽  
Dry Weight ◽  
Surface Flow ◽  
Hyporheic Exchange ◽  
Pore Scale ◽  
River Bank

Abstract Although recent studies indicate that fluvial systems can be accumulation areas for microplastics (MPs), the common perception still treats rivers and streams primarily as pure transport vectors for MPs. In this study we investigate the occurrence of MPs in a yet unnoticed but essential compartment of fluvial ecosystems - the hyporheic zone (HZ). Larger MP particles (500–5,000 µm) were detected using attenuated total reflectance (ATR) - Fourier-transform infrared (FTIR) spectroscopy. Our analysis of MPs (500–5,000 µm) in five freeze cores extracted for the Roter Main River sediments (Germany) showed that MPs were detectable down to a depth of 0.6 m below the streambed in low abundances (≪1 particle per kg dry weight). Additionally, one core was analyzed as an example for smaller MPs (20–500 µm) with focal plane array (FPA)- based µFTIR spectroscopy. Highest MP abundances (~30,000 particles per kg dry weight) were measured for pore scale particles (20–50 µm). The detected high abundances indicate that the HZ can be a significant accumulation area for pore scale MPs (20–50 µm), a size fraction that yet is not considered in literature. As the HZ is known as an important habitat for invertebrates representing the base of riverine food webs, aquatic food webs can potentially be threatened by the presence of MPs in the HZ. Hyporheic exchange is discussed as a potential mechanism leading to a transfer of pore scale MPs from surface flow into streambed sediments and as a potential vector for small MPs to enter the local aquifer. MPs in the HZ therefore may be a potential risk for drinking water supplies, particularly during drinking water production via river bank filtration.

scholarly journals Zn sorption on Ca-illite and Ca-smectite: experiment and modelling

2019 ◽  
Vol 98 ◽  
pp. 04008
Author(s):  
Christelle Latrille ◽  
Aubéry Wissocq ◽  
Catherine Beaucaire
Keyword(s):  
Ion Exchange ◽  
Clay Minerals ◽  
Sorption Isotherms ◽  
Ion Exchanger ◽  
Natural Environments ◽  
Sorption Site ◽  
Batch Experiments ◽  
Sorption Data ◽  
Relevant Role ◽  
Site Types

To predict Zn behaviour in soil, the retention properties of clay minerals plays a relevant role. In a continental environment, Ca is the main cation in solution. Soil reactivity may be reduced to sorption properties of Zn and Ca on illite and smectite, the major clay minerals in soil. With this assumption, a multi-site ion exchanger model has successfully been applied to the Zn sorption on Ca-illite and Ca-smectite. New batch experiments performed in this study enabled to collect sorption data for Zn on Ca-illite by concentration and pH isotherms. Zn sorption reversibility was then verified. These sorption data were modelled successfully with a multi-site ion exchanger (MSIE) formalism by using four sorption site types. Zn sorption isotherms on smectite were retrieved from literature and interpreted following the MSIE formalism. The obtained selectivity coefficients may be thereafter put into ion exchange models to describe the Zn sorption in natural environments.

Removal of odorant dimethyl disulfide under alkaline and neutral conditions in biotrickling filters

2012 ◽  
Vol 66 (8) ◽  
pp. 1641-1646 ◽  
Author(s):  
L. Arellano-García ◽  
A. González-Sánchez ◽  
H. Van Langenhove ◽  
A. Kumar ◽  
S. Revah
Keyword(s):  
Main Product ◽  
Dimethyl Disulfide ◽  
Continuous Treatment ◽  
Batch Experiments ◽  
Reduced Sulfur Compounds ◽  
Biotrickling Filters ◽  
Bacterial Consortia ◽  
Low Concentrations ◽  
Alkaline Conditions ◽  
Neutral Conditions

The aim of this paper was to evaluate the performance of biotrickling filters (BTFs) for treating low concentrations of dimethyl disulfide (DMDS), using different bacterial consortia adapted to consume reduced sulfur compounds under alkaline (pH ≈ 10) or neutral (pH ≈ 7) conditions. Solubility experiments indicated that the partition of DMDS in neutral and alkaline mineral media was similar to the value with distilled water. Respirometric assays showed that oxygen consumption was around ten times faster in the neutrophilic as compared with the alkaliphilic consortium. Batch experiments demonstrated that sulfate was the main product of the DMDS degradation. Two laboratory-scale BTFs were implemented for the continuous treatment of DMDS in both neutral and alkaline conditions. Elimination capacities of up to 17 and 24 gDMDS m−3 h−1 were achieved for the alkaliphilic and neutrophilic reactors with 100% removal efficiency after an initial adaptation and biomass build-up.

Removal of Copper from Vineyard Soil by Washing with Biosurfactant

2014 ◽  
Vol 1065-1069 ◽  
pp. 3091-3095
Author(s):  
Da Zhao ◽  
Yue Zhao ◽  
Shi Bo Tao
Keyword(s):  
Removal Efficiency ◽  
Contact Time ◽  
Ph Value ◽  
Batch Experiments ◽  
Liquid Ratio ◽  
Washing Process ◽  
Vineyard Soil ◽  
Alkaline Conditions ◽  
Solid Liquid ◽  
Fermentation Solution

The washing process in batch experiments was conducted to investigate the performance of fermentation solution on removal copper(Cu) from vineyard soil. The effects of solid-liquid ratio, pH value and contact time on the removal capacities of Cu by fermentation solution had been studied. The results showed that the optimum solid-liquid ratio was 1:10 for soil treatment. The fermentation solution showed a better removal efficiency of Cu in alkaline conditions, getting the highest removal efficiency of 34.3%. In addition, with the increase of contact time, higher removal efficiency was obtained.

Sorption of magnesium–picolinate complexes on a macroporous styrene–divinylbenzene copolymer containing immobilized 8-hydroxyquinoline and on the copolymer itself

1992 ◽  
Vol 70 (3) ◽  
pp. 926-930 ◽  
Author(s):  
Gocool Persaud ◽  
Frederick F. Cantwell
Keyword(s):  
Picolinic Acid ◽  
Sorption Isotherms ◽  
Magnesium Ion ◽  
Ligand Complex ◽  
Solution Ph ◽  
Complex Species ◽  
Linear Sorption ◽  
Atomic Absorption Technique ◽  
Styrene Divinylbenzene ◽  
Absorption Technique

The sorbent XAD-OXINE was prepared by covalently binding 8-hydroxyquinoline onto the surface of the macroporous copolymer Amberlite XAD-2 to give about 20% surface coverage. Sorption, onto both XAD-2 and XAD-OXINE, of the magnesium-containing species that are present in solutions of magnesium ion and picolinic acid was studied by the column equilibration/atomic absorption technique at solution pH of 6.00 and 7.50 and ionic strength of 0.25. By using solutions containing various amounts of added magnesium and picolinic acid, in which the ratio of the two metal–ligand complex species, MgP+/MgP2, varied greatly (P− is the ligand picolinate), it was shown that neither the species Mg2+ nor the species MgP+ sorb to an appreciable extent onto the parent polymer XAD-2, but the neutral species MgP2 sorbs strongly and exhibits a linear isotherm. Then, by measuring the sorption isotherm of the species Mg2+ on XAD-OXINE in the absence of picolinic acid, by measuring the overall sorption of magnesium-containing species on XAD-OXINE in the presence of picolinic acid, and by assuming that the sorption of the species MgP2 onto XAD-OXINE was about the same as it was on XAD-2, it was possible to show that the species MgP+ sorbs strongly onto XAD-OXINE, and exhibits linear sorption isotherms. Thus, XAD-OXINE sorbs all three species Mg2+, MgP+, and MgP2. Keywords: Amberlite XAD-2, immobilized oxine, magnesium ion.

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