Comparative study of granitic and sedimentary groundwater colloids by flow-field flow fractionation coupled with ICP-MSby T. Saito, T. Hamamoto, T. Mizuno, T. Iwatsuki, S. Tanaka

J. Anal. At. Spectrom.


Analytical Chemistry / Spectroscopy


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Wilbert van de Ven, Ineke Pünt, Antoine Kemperman, Matthias Wessling


Comparative stud groundwater coll . r t s

F to

I si s a d g 1. Introduction

Natural colloids are inorganic cules, or their composites, havin mm; they can be found in various rivers, the ocean, and groundw colloids are clay minerals and which result from chemical weat organic colloids are humic sub organic materials resulting from sation of the remains of plants, a

Natural colloids readily interac modify their reactivity, bio-avai pollutants can be captured by h substances;4 metal ions such as t can bind to functional groups colloids or to those inside the str

As the transport behaviors of co rather different from those of small contaminant molecules,



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L ib ra ry o n 26 /0 5/ 20 15 0 4: 02 :5 7. aAdvanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata

Shirane, Tokai-mura, Ibaraki 319-1195, Japan. E-mail: bDepartment of Nuclear Engineering and M

University of Tokyo, 7-3-1 Hongo, Bunkyo-ku cHoronobe Underground Research Center

Hokushin, Horonobe-cho, Hokkaido 098-322 dMizunami Underground Research Laborat

Yamanouchi, Akeyo-cho, Mizunami-shi, Gifu † Former professor of the Department of

School of Engineering, The University of T

This journal is © The Royal Society ofparticles, organic macromoleg sizes ranging from 1 nm to 1 environments including soils, ater.1 Examples of inorganic iron (oxy)hydroxides, both of hering of host rocks;2 those of stances, which are refractory decomposition and condennimals, and microorganisms.3 t with various pollutants and lability, and toxicity. Organic ydrophobic moieties of humic race metals and radionuclides on the surfaces of mineral uctures of organic colloids.3,5,6 lloids in the environment are due to the differences in their sizes and charge densities, their binding to natural colloids can signicantly alter the mobility of contaminants.7 In some cases natural colloids can facilitate their transport.7–10 This is of great concern for geological disposal of nuclear waste,11 as the safety of the disposal must be assessed by considering the migration of radionuclides released from a deep underground repository.

The nature and amount of colloids in deep groundwater has been an active topic of research for decades.12–15 Vilks et al.12 reported the existence, concentration, and size distribution of groundwater colloids in different geological settings in Canada, using ultraltration. Those authors also evaluated the retention of naturally occurring radionuclides such as radium (Ra), thorium (Th), and uranium (U) in groundwater colloids.

Degueldre, et al.13 characterized colloids sampled in granitic groundwater and studied their stability and mobility. Criteria for colloid-facilitated transport of contaminants have been proposed, based on reviews of relevant eld studies and laboratory experiments.14

One of the difficulties encountered in the analysis of naturalfractionation cou

T. Saito,*a T. Hamamoto,b T

Colloids in deep underground wate concern in the safety assessmen elemental compositions of colloid flow-field flow fractionation (Fl-F (ICP-MS). Great care was taken elements associated with them. elements were found in limited suggested in this groundwater. Mo nm, which largely overlapped with small organic and probably inorg colloids. Organic colloids in this compositions of chromophores an depended on their types, indicatin

Cite this: DOI: 10.1039/c5ja00088b

Received 16th March 2015

Accepted 13th May 2015

DOI: 10.1039/c5ja00088b, School of Engineering, The , Tokyo 113-8656, Japan , Japan Atomic Energy Agency, 432-2 4, Japan ory, Japan Atomic Energy Agency, 1-64, 509-6132, Japan

Nuclear Engineering and Management, okyo.

Chemistry 2015y of granitic and sedimentary oids by flow-field flow pled with ICP-MS

Mizuno,c T. Iwatsukid and S. Tanaka†b play an important role in themigration of radionuclides and are of great of the geological disposal of nuclear wastes. Size distribution and in granitic and sedimentary deep groundwater were determined by

F) combined with inductively coupled plasma mass spectrometry examine colloids over a wide range of size and to detect trace n the granitic groundwater organic colloids and various inorganic ze ranges. The presence of different types of organic colloids was t of the inorganic elements exhibited similar size distributions at <10 organic colloids rich in fluorophores. In the sedimentary groundwater nic colloids were found at <5 nm together with larger inorganic groundwater were homogeneous in terms of their sizes and the fluorophores. The size distribution of inorganic elements at <10 nm the presence of different host colloidal phases.

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View Journalcolloids is the heterogeneity both in their size and composition.

Colloids found in natural water samples tend to exist over a wide range of sizes and consist of different types of materials associating with each other.16,17 Conventional (ultra)ltration techniques only provide discrete information and may not fully resolve such heterogeneity. This is also the case for groundwater colloids. Only recently has detailed size distribution and

J. Anal. At. Spectrom.

JAAS Paper

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View Article Onlinecomposition of natural colloids become available with emergence of continuous size fractionation techniques such as oweld ow fractionation (Fl-FFF),18–21 size exclusion chromatography (SEC),22,23 and capillary electrophoresis.24,25 These techniques can easily be combined with different types of detection methods to probe various properties of colloids.20–23

In Fl-FFF colloids are forced to accumulate near a so-called accumulation wall that is made of a membrane largely permeable for solute and solvent molecules by a force eld created by cross ow.26 Smaller colloids tend to be distributed far away from the wall due to their large thermal mobility and are transported faster than larger ones by parabolic laminar tip ow. Fl-FFF has certain advantages over the other techniques: the range and resolution of fractionation can be easily adjusted by changing ow parameters; in theory the retention time of a given colloidal particle, which is the time necessary for the particle to travel through the channel of the Fl-FFF and reach a detector, mathematically relates to its diffusion coefficient and thus to its hydrodynamic diameter (dH). This technique has been widely applied for environmental colloids in surface water and shallow groundwater,18,20,21 but has not been applied for those in deep groundwater mostly due to the relatively low concentrations of colloids in deep groundwater and the difficulty in obtaining deep groundwater samples.19