Distribution of beryllium between solution and minerals (biotite and albite) under atmospheric conditions and variable pH

Chemical Geology 156 Ž1999. 209–229

Distribution of beryllium between solution and minerals žbiotite and albite / under atmospheric conditions and variable pH A. Aldahan a

a,)

, Ye Haiping a , G. Possnert

b

Institute of Earth Sciences (Quaternary Geology), Uppsala UniÕersity, S-752 36 Uppsala, Sweden b Tandem Laboratory, Uppsala UniÕersity, S-752 36 Uppsala, Sweden Received 27 October 1997; accepted 23 October 1998

Abstract Biotite and albite grains having a size range from 20 to 124 mm were suspended in Be-bearing solutions at pH 2 to 9 for periods of 30 min to 20 days. The amount of Be sorbed onto biotite is up to 40 times higher than onto albite under the same conditions and pH F 7. At pH F 6, the distribution of Be between solution and solids is related to sorption but at pH ) 6, the solute concentration is strongly controlled by solubility of BeŽOH. 2-solid . Because of this solubility control, the calculation of a distribution coefficient Ž K d s SrC, where S is Be sorbed at equilibrium per mass or specific surface area of sorbent, and C is the Be concentration in solution at equilibrium. seems to be valid only at pH F 6. The K d increases with decreasing suspended particle concentration Žfrom 0.2 to 2.0 g ly1 . for both minerals. For biotite the K d also increases with the fine Ž20–63 mm. relative to the coarse Ž63–124 mm. size fraction even upon normalization to specific surface area. The relatively small amount of Be sorbed onto albite at pH 2 and 4 limited extensive evaluation and comparison. The rate of Be sorption onto biotite follows a logarithmic function and ranges from 0.8 to 1.0 = 10y11 mol cmy2 sy1 in pH 2 and 6 solutions, respectively. The time-variation of sorbed Be onto albite was insignificant with increasing pH. The sorption of Be onto biotite partly relates to the kinetics of cation release. The results of experiments are discussed with respect to some examples of the distribution of Be isotopes in continental aquatic systems. q 1999 Elsevier Science B.V. All rights reserved. Keywords: Beryllium; Biotite; Albite; Distribution coefficient; Sorption

1. Introduction Beryllium has one stable Ž9 Be. and six radioactive isotopes. 10 Be has a half-life of 1.51 " 0.06 = 10 6 years ŽHofmann et al., 1987. and 7 Be has a half-life of 53.4 days ŽNyffeler et al., 1984.. 6 Be, 8 Be, 11 Be )

Corresponding author. Tel.: q46-18471-3095; E-mail: [email protected]

and 12 Be decay within a fraction of a second. Stable beryllium Ž9 Be. and radioactive isotopes Ž10 Be and 7 Be. have wide applications in several branches of science and industry. For example, 9 Be, as a unique and valuable metal, has important uses in today’s nuclear, aerospace and electronics industries ŽSkilleter, 1990.. 9 Be and 10 Be have been used in petrogenesis and chronometry of marine ŽSegl et al., 1984; Mangini et al., 1984; Ku et al., 1985; Bourles ´

0009-2541r99r$ - see front matter q 1999 Elsevier Science B.V. All rights reserved. PII: S 0 0 0 9 - 2 5 4 1 Ž 9 8 . 0 0 1 8 6 - 7

210

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

et al., 1989; Aldahan et al., 1994, 1997. and continental sediments ŽBrown et al., 1981; Monaghan et al., 1992; Shen et al., 1992; Pavich and Vidic, 1993; Shi Ning et al., 1994; Gu et al., 1996.. 10 Be, and in some cases 7 Be, have also been used to trace other geologic events such as solar activity ŽBeer et al., 1990; Aldahan et al., 1995; Possnert et al., 1995., stratosphere–troposphere interaction Že.g., Dibb et al., 1992., rainfall and aerosols precipitation ŽKnies et al., 1994., surface current circulation in the ocean ŽRaisbeck et al., 1980; Olsen et al., 1986. and exposure dating of glacial retreat ŽGosse et al., 1995; Brook et al., 1996.. In order to understand the distribution of beryllium isotopes during transport and deposit in aquatic systems, the distribution of Be between solids and solutions has been investigated. For example, Olsen et al. Ž1986. studied the natural 7 Be distribution in river–estuarine and coastal water, with emphasis on the relationship between the distribution coefficient Ž K d . and the length of equilibration time. Hawley et al. Ž1986. investigated the distribution of 7 Be in fresh water and showed the dependence of K d on solid concentration. You et al. Ž1989. showed the distribution of 7 Be between soil and river or sea water to be strongly dependent on pH and the concentration of suspended particles. All these studies indicated a wide range for the K d of Be. Also, the use of 7 Be Žhalf-life 53.4 days. put constraints on the calculated K d values during equilibration times up to a few weeks. Furthermore, the published studies available did not deal with the effect of individual minerals, mineral dissolution processes and grain size, or specific surface area, on the rate of Be distribution. In this study, the effects of pH, grain size, specific surface area, suspended particle concentration and mineral dissolution kinetics on the distribution of 9 Be are considered. Biotite and albite were chosen as solid particles, because: Ž1. they are common minerals in earth surface environments; Ž2. their sorption of Be has not been investigated before; Ž3. biotite occurrence is spread over a wide grain size range Žclay to sand fractions. in sediments and Ž4. albite is, relative to other feldspars, chemically more stable during sedimentation processes. Quartz was used as a reference to compare the effect of crystal–chemical parameters on the sorption of Be onto biotite and

albite. The ratio of solution–solid and 9 Be–solids and other experimental parameters were selected to closely reflect those occurring during continental sedimentation processes. We have used, relatively, several orders of magnitude higher Be concentration than in natural waters, in order to accommodate the possibility of Be discharge from industrial sources. The amount of soluble 7 Be and 10 Be in continental aquatic systems is much less than 9 Be, but all the three isotopes seem to follow similar general distribution trends, as discussed later in the text.

2. Experimental methods 2.1. Materials The biotite, albite and quartz used in the experiments were taken from the collection of the mineralogical museum of the Institute of Earth Sciences, Uppsala University. The minerals were dry-ground by hand in an agate mortar and particle sizes of 20 to 63 and 63 to 124 mm were dry-sieved. Each grain size fraction was ultrasonically cleaned to remove fines, and dried in an oven at 408C. The specific surface area of the minerals in the two grain size fractions were measured by the Brunauer–Emmett– Teller ŽB.E.T.. method, using nitrogen adsorption, and the results and analytical error Ž1 standard deviation. are listed in Table 1. The mineralogical purity of the samples was checked by using a Phillips ŽPW 1710. diffractometer having a Ni-filtered Cu-k-alpha radiation and microscopic examination. The samples were measured at a scanning rate of 1.28 miny1 and in the range 2 u s 5–608. Within the resolution power of the X-ray diffraction Žerror of "5%., the results indicate a high purity of the standard phases used. Biotite appeared to be less pure Žabout 95–97%. than albite Žabove 99%.. The transmitted-light microscopic examination of thin sections did not reveal contamination of the biotite with other mineral phases. A 100% pure biotite sample is unusual in rocks exposed to erosion and sedimentation as this mineral is easily affected by such processes. The most common feature is the ultra-fine submicroscopic Žmicron or less. intergrowth of chlorite, illite and kaolinite Že.g., Aldahan and Morad, 1986., which

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229 Table 1 Specific surface area and chemical composition of the studied albite and biotite Albite

Biotite

211

pH 2. The Be-solutions of pH 4, 6, 7 and 9 were prepared by adding dilute NaOH. 2.2. Experimental procedure

Grain size 20–63 mm 63–124 mm

Specific surface areas Žm2 gy1 . 10.15"0.5 0.48"0.09 7.89"0.4 0.07"0.03 wt.%

wt.%

SiO 2 Al 2 O 3 CaO FeO K 2O MgO MnO Na 2 O P2 O5 TiO 2 Total Be Žmgrg.

68.9"0.1 19.0"0.1 0.22"0.01 0.054"0.005 0.390"0.001 0.017"0.005 - 0.001 10.8"0.1 0.03"0.01 0.005"0.001 99.4 3.8

34.9"0.2 14.7"0.1 0.12"0.01 27.4"0.2 8.64"0.01 8.33"0.04 0.264"0.01 0.099"0.009 0.03"0.01 2.10"0.01 96.6 2.2

cannot, in practice, be avoided. Thus, the biotite used in this study is accepted as being a fair representation of the natural particles that are exposed to earth surface processes. The chemical compositions of the biotite and albite are given in Table 1. The chemical analysis was performed with an ARL 3580 optical emission spectrometer equipped with inductively coupled plasma excitation. The analytical method involved melting of a 0.125 g sample with 0.375 g LiBO 2 and dissolution of the mixture in HNO 3 . The chemical formulas of biotite based on 10 oxygens and 2 hydroxyls, and albite based on 8 oxygens, are: biotite—K 0.86 ŽAl 0.10 Mg 0.97 Ti 0.12 Mn 0.02 Fe1.80 .ŽAl 1.26 Si 2.74 .O 10 ŽOH. 2 , albite—Na 0.92 K 0.02 Ca 0.01Al 0.98 Si 3.02 O 8 . Metal 9 Be was dissolved in 8 M HCl and by dilution, a solution Ž0.01 M. containing 5 mg Be per ml Ž0.56 mmol ly1 . was made for the experiment at

The experimental conditions are summarized in Table 2. In order to have a close resemblance to continental aquatic systems and have a large enough amount of sample to work with, a solid Žbiotite or albite. –solution ratio of 0.2 to 2 g ly1 was used. Similarly, the mass ratio of 9 Be in solution to solid particles was maintained at values between 2.5 = 10y5 and 2.5 = 10y6 which are comparable to ranges in riverine and lake water having pH F 7 Že.g., Loreti, 1988; Brown et al., 1992.. The experimental procedure starts by putting 50 mg of mineral powder into a polyethylene bottle to which 25 ml of Be solution with a given pH was added. The bottle was automatically shaken to keep the solids in suspension at room temperature. After a certain time, the bottle was centrifuged and a clear solution was obtained, on which pH was immediately measured. The solid particles in the bottle were left to dry at room temperature. For each grain size fraction and for each pH value, 4–10 bottles were prepared in parallel under the same conditions, but run at different intervals of time Žfrom 30 min to 20 days.. Altogether 100 samples were measured. In addition, 15 samples were measured with various concentrations of suspended particles. Reagent blanks for each experimental run were checked. There were no significant changes in pH of the solution during each experiment, i.e. within the instrumental error Ž"0.05., and no measurable Be sorbed onto the walls of the bottles and glassware used. The determinations of Be, Si, Al, Fe, Mg and Na in solutions were carried out with a SP9 Pye Unicam atomic absorption spectrophotometer using a nitrous-acetylene flame for Be, Si and Al and an

Table 2 Experimental conditions used in this study Minerals

Solid concentration Žg ly1 .

Grain size Žmm.

pH

Time Žday.

Elements measured

Biotite

2 1, 0.5, 0.2 2 1, 0.5, 0.2

20–63, 63–124 63–124 20–63, 63–124 63–124

2, 4, 6, 7, 9 2, 6, 9 2, 4, 6, 7, 9 2,6

0–20 10 0–20 10

Be, Si, Al, Fe, Mg Be, Si, Al, Fe, Mg Be, Si, Al, Na Be, Si, Al, Na

Albite

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

212

air–acetylene flame for Fe, Mg and Na. The analytical error is 3%, 1 standard deviation, but may reach to 8% at concentration - 0.01 mmol ly1 . Selected patches of biotite and albite were analysed by X-ray diffraction, Scanning Electron Microscope ŽPhilips model 30 with EDAX. and Atomic Force Microscope ŽNanoscope III. to get some understanding of mineral alteration during the experiments.

3. Results 3.1. Sorption of Be The distribution of Be between biotite and solution indicates that Be sorption increases with time ŽTable 3. for the two grain sizes 20–63 mm and 63–124 mm as pH increases ŽFig. 1a.. The distribution of Be between albite and solution ŽTable 3 and

Table 3 Results of the Be concentration Žin solution. from the batch experiments at particle concentration of 2 g ly1 Minerals

Grain size Žmm.

Time Žh.

Be concentration Žmmol ly1 . in solutions pH 2

Biotite

20–63

63–124

Albite

20–63

63–124

0.5 1 3 6 8 18 24 72 120 240 480 0.5 1 8 24 72 120 240 480 0.5 1 3 6 8 18 24 72 120 240 480 0.5 1 8 24 72 120 240 480

pH 4

0.50 0.48 0.48 0.47 0.47 0.46 0.44 0.43 0.42 0.40 0.54 0.53 0.52 0.51 0.50 0.49 0.48 0.47

0.41

0.42

pH 6

pH 7

pH 9

0.29

0.010

0.23

0.001

0.21 0.21 0.19 0.19 0.18 0.34

0.001 0.001 0.004 0.001 0.001 0.007

0.30 0.29 0.28 0.28 0.26 0.25

0.54 0.53 0.52 0.54

0.49 0.49 0.48 0.49

0.54 0.54 0.54 0.55 0.55 0.55 0.55 0.55 0.55 0.54 0.53 0.53 0.54 0.53

0.49 0.48 0.49 0.49 0.47 0.49 0.49 0.49 0.46 0.47 0.48 0.44 0.44 0.44

0.005

0.003

0.002 0.002 0.002 0.007 0.001 0.001 0.013

0.001

0.52

0.53

0.021

0.025

0.001 0.002 0.001 0.003 0.001 0.003 0.001 0.001 0.002 0.001 0.001 0.001

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

213

Fig. 1. The variation of Be concentration in solution with pH for suspended particle concentrations of 2 g ly1 biotite Ža. and albite Žb. after 20 days Ž480 h. of experimental run.

Fig. 1b. did not reveal a significant sorption Ž- 10%. over a period of 20 days for the two fractions at pH 2, 4 and 6. Compared with the amount sorbed onto biotite ŽFig. 1a., the sorbed Be onto albite is close to the analytical error range Ž3–8%.. The sorption onto

biotite at pH 2 and 6 solutions reveals a steeply increasing amount of sorbed Be during the first two days ŽFig. 2a and b.. Also more Be is sorbed onto biotite at pH 6 relative to pH 2. After 20 days of equilibration, the percentages of sorbed Be onto the

Fig. 2. The variation of Be concentration in solution with time and grain size for biotite and albite batch experiments at 2 g ly1 particle concentration and pH 2 Ža and c. and pH 6 Žb and d..

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

214

Table 4 Be concentration Žin solutions. and K d for the size fraction 63–124 mm at variable suspended particle concentrations and after 10 days Ž240 h. experimental run Minerals

Cp Žg ly1 .

pH 2

Biotite

Albite

K da

Be Žmmol ly1 . pH 6

2.00

0.48

0.26

1.00

0.48

0.32

0.50

0.49

0.35

0.20

0.52

0.33

2.00

0.54

0.44

1.00

0.53

0.44

0.50

0.53

0.45

0.20

0.54

0.45

pH 2

pH 6 A

B

82 0.10 152 0.19 278 0.35 343 0.44

560 0.71 720 0.95 1160 1.47 3310 4.20

20 0.025 25 0.032 410 0.52 1160 1.47

19 2.71 42 6.00 90 12.86 177 25.29

140 20.00 260 37.10 470 67.14 1140 162.8

50 7.14 90 12.86 160 22.86 400 57.14

a

K d Žml gy1 . and Žml cmy2 = 10y2 .. ŽA. based on measured concentration. ŽB. based on concentration corrected for BeŽOH. 2-solid effect Ž K dcorr see text for details..

fine and coarse grain biotite were 27.4 and 15.6 at pH 2, 26.1 and 24.3 at pH 4 and 68.3 and 54.2 at pH 6, respectively. The Be distribution in pH 9 solution indicates direct Žwithin minutes. removal of Be from the solution and did not vary with time ŽTable 3.. Rather similar behaviour, direct removal of Be from solution, was observed for experiments of pH 7, but

after a few hours of the run. However, the runs at pH 7 were continued for 20 days. The sorption experiments of Be onto biotite and albite for different concentrations of suspended particles Ž0.2–2 g ly1 . were run for 10 days ŽTable 4 and Fig. 3.. The data indicate that larger amounts of Be are sorbed in pH 6 solution than in pH 2 for both

Fig. 3. The variation of Be concentration Žin solution. vs. suspended particle concentration of biotite Žrings. and albite Žsquares. at solution pH 2 Ža. and 6 Žb..

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

minerals. The Be remaining in the solution decreases with increasing amounts of biotite but does not show a significant change for the different amounts of albite ŽFig. 3.. The sorption of Be onto quartz at pH 2 and 4 was negligible after a 20-day run and thus no further experimentation and calculation was made. 3.2. Estimation of the distribution coefficient (K d ) of Be The definition of an adsorption process as given by the CRC handbook of chemistry and physics ŽWeast and Melvin, 1981. is ‘the condensation of

215

gases, liquids, or dissolved substances on the surfaces of solids’. The sorption process has no definition in that book, but is defined by Birkett et al. Ž1988. as ‘the removal of solute components from the aqueous phase of an environmental system by the solid phaseŽs. at the surface of the solid phaseŽs.’. Both definitions have no specific kinetic or mechanistic implications and we shall use the term sorption as an umbrella for both terms in the present context. Several chemicalrmathematical approaches were used to quantitatively describe sorption processes Že.g., Birkett et al., 1988 and references therein., generally assuming that thermodynamic equilibrium conditions are reached between the liquid and

Fig. 4. Distribution coefficient Ž K d ml gy1 . of Be vs. pH for biotite Ža. and albite Žb. at particle concentration of 2 g ly1 . Note that we plotted the K d values for pH 7 and 9, although they are not valid, just for easy visual comparison. The K d values for pH 6 and 7 solutions are the measured values Žsee Table 4 and text for details.. The specific surface area normalized K ds of the biotite and albite are shown in Žc..

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

216

solidŽs.. One such approach is to calculate the distribution coefficient Ž K d ., as is done here for Be: K d s SrC

Ž 1. Ž 2.

S s YrCp

where S s Be sorbed at equilibrium per mass of sorbent Žmmol gy1 ., C s Be concentration in solution at equilibrium Žmmol ly1 ., Y s Be concentration attenuated Žmmol ly1 ., Cp s suspended particle concentration Žg ly1 .. All published literature data on the K d of Be are reported in units of volumerweight Žml gy1 ., and to be able to compare our data with the literature, we have used the same units. However, we have also calculated the K d in units of volumerspecific surface area Ž K ds s ml cmy2 .. The K d values for biotite and albite at four different suspended particle concentrations Ž10 days run at pH 2 and 6. are higher in pH 6 than those in pH 2 solutions ŽTable 4 and Fig. 4.. Also the K d values for biotite are higher than for albite at both pH values. The K d values at pH range 2–7 Ž20 days run and 2 g suspended particles ly1 . for biotite are several times higher than those for albite ŽTable 5.. However, albite shows higher K ds values than biotite. The K d for both minerals increases with decreasing suspended particle concentration ŽFig. 5.. The fine grain Ž20–63 mm. biotite shows higher K d Table 5 The K d for the two grain size fractions of biotite and albite at particle concentration of 2 g ly1 and after 20 days Ž480 h. of experimental run Mineral Grain size K da Žmm. pH 2

pH 4

pH 6 A

Biotite 20–63 63–124 Albite

20–63 63–124

a

pH 7 A

B

189 175 1080 380 0.19 0.17 1.06 0.37 93 155 590 210 0.12 0.20 0.75 0.27

B

57 700 56.8 82 800 104.9

1700 1.68 2400 3.04

6 39 70 20 0.13 0.81 1.45 0.41 25 26 130 50 3.57 3.71 18.6 7.14

12 900 268.8 10 700 1528

400 8.33 300 42.9

K d Žml gy1 for the first row, ml cmy2 =10y2 for the second row. for each grain size. ŽA. based on measured concentration. ŽB. based on concentration corrected for BeŽOH. 2 effect Ž K dcorr see text for details..

Fig. 5. Distribution coefficient Ž K d and K ds . of Be vs. particle concentrations Ž63–124 mm fraction. of biotite and albite in pH 2 and pH 6 solutions. Note that the K d for pH solution are uncorrected values Žsee Table 5..

values than the coarse Ž63–124 mm. ones, except at pH 4 where the K ds is slightly higher in the coarse relative to the fine fraction. For albite, there seems to be no specific trend between K d and grain size, and because of the large error Žas mentioned above. in both the Be concentrations and specific surface area ŽTables 3 and 1., the albite data must be interpreted with caution. As mentioned above, Be concentrations in pH 9 solution did not show time-dependent relation and thus give a calculated K d of about 2.5 = 10 5 ml gy1 for all experiments, irrespective of the solid phase component Že.g., biotite or albite.. This calculation is not valid as will be explained in Section 4.

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

3.3. The rate of Be sorption by biotite The amount of Be sorbed onto the biotite vs. time for the pH 2 and 6 experiments may be best described by Eq. Ž3. below: dCsrdt s k 1 ty1 .

Cs s k 1 log t q A,

Table 6 Rate of Be sorption onto biotite at particle concentration of 2 g ly1 and after 20 days Ž480 h. of experimental run pH

Grain size Žmm.

Sorption rate Ž10y1 1 mol cmy2 sy1 .

2

20–63 63–124 20–63 63–124

0.8 0.8 1.0 1.0

Ž 3.

The relationship between Be sorbed onto biotite Ž Cs . and time Ž t . is then logarithmic as follows:

217

6

Ž 4.

where k 1 is the rate constant and A is an integration constant. The plots of Be concentration Ž Cs . against log t ŽFig. 6. indicate correlation coefficients Ž r . between 0.96 and 0.99. The basic assumption inherent in Eq. Ž3. is that the rate is dominantly defined for the Be 2q species, which is the most reasonable approach when considering the pH range F 6. The rate of Be sorbed onto biotite Žfrom the slope of linear fits, Fig. 6. is 0.8–1.0 = 10y1 1 mol cmy2 sy1 and is dependent on the pH of the solution ŽTable 6.. 3.4. Dissolution of biotite and albite The results of biotite dissolution ŽTable 7. indicate that the ratios of Si, Al and Fe released by the fine grains relative to the coarse grains after 20 days are 2.0 and the ratio of Mg is 1.7. Biotite dissolution retards at pH 4 to 7, but increases slightly again at pH 9. The concentration of released Si and Al upon reaction of biotite with pH 2 solution indicates a successive increase, by the two size fractions, with time ŽFig. 7a and b.. Dissolution of the fine fraction

Fig. 6. Rate of Be sorption onto biotite and albite in pH 2 and 6 solutions and at particle concentration of 2 g ly1 .

Ž20–63 mm. is characterized by a sharp increase of Fe and Mg release during the first two days. This is followed by a subsequently gentler increase and the Table 7 Results of cations release Žin solution. from biotite batch experiments at particle concentration of 2 g ly1 Time Žh.

Concentration Žmmol ly1 . Si

Al

Fe

Mg

0.57 0.61 0.74 0.76 0.92 1.00 1.32 1.55 1.76 2.19

0.43 0.68 0.84 0.94 1.35 1.53 1.81 1.90 2.02 2.08

0.17 0.18 0.22 0.24 0.32 0.35 0.42 0.44 0.45 0.46

pH 2 solution (63 – 124 m m) 0.5 0.041 0.071 1 0.10 0.073 8 0.16 0.15 24 0.24 0.25 72 0.46 0.45 120 0.71 0.64 240 1.07 0.87 480 1.46 1.12

0.076 0.088 0.19 0.33 0.59 0.89 0.97 1.04

0.018 0.021 0.033 0.054 0.14 0.19 0.25 0.28

pH 4 solution (63 – 124 m m) 480 0.047 0.002

0.013

0.032

pH 6 solution (63 – 124 m m) 480 0.014 0.012

0.001

0.004

pH 7 solution (63 – 124 m m) 480 0.010 0.001

0.002

0.017

pH 9 solution (63 – 124 m m) 240 0.061 0.39

0.001

0.003

pH 2 solution (20 – 63 m m) 0.5 0.52 1 0.60 3 0.71 6 0.69 18 0.81 24 0.96 72 1.39 120 1.64 240 2.16 480 2.88

218

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

Fig. 7. The release cations from biotite Ža–d. and albite Že. in pH 2 solution and at particle concentration of 2 g ly1 after 20 days Ž480 h. of experimental run.

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

reaching of a likely steady state ŽFig. 7c and d.. Similar behaviour is also demonstrated by the coarse Ž63–124 mm. fraction, but the increase is smoother and lasts up to 5 days. Upon dissolution, the surface texture of the untreated biotite ŽFig. 8a. is extensively altered through formation of etch pits ŽFig. 8b and c. and planar surfaces are developed when the cation release attains a likely steady state ŽFig. 8d.. Further examination of these dissolution surfaces with the atomic force microscope ŽAFM. confirms the rather smooth and flat surfaces of the untreated biotite, even on the nm scale ŽFig. 9a.. The AFM ˚ scale examination reveals a relief difference on the A in the minute etched surfaces ŽFig. 9b. of the experimentally treated biotite that cannot be clearly exposed by SEM. The amounts of Si, Al, Fe and Mg

219

released from biotite dissolution in pH 2 solution increase with increasing concentration of suspended particles ŽFig. 10.. The small proportion, only 0.4–0.7%, of Si, Al and Na released from albite relative to biotite dissolution did not, considering the error of the analysis, permit detailed evaluation of albite dissolution behaviour as was the case with biotite ŽFig. 7e.. Nevertheless, the general dissolution as shown by Table 8, indicates similarity to biotite with respect to pH of solution and grain size. Relatively, larger amounts of Si and Al are released from finer than from coarser grains and in solutions of pH 2 and pH 9 relative to the other solutions. The amount of released Na was measured only in pH 2 solution as additions of Na Žas NaOH. were used in the other pHs and thus

Fig. 8. SEM photographs showing changes in surface texture of the untreated Žoriginal. biotite Ža. after reaction in pH 2 solution for 5 days Ž120 h. Žb and c. and 20 days Ž480 h. of experimental run.

220

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

221

Table 8 Results of cations release Žin solution. from albite batch experiments at particle concentration of 2 g ly1 Time Žh.

Concentration Žmmol ly1 . Si

Fig. 10. The concentrations of released cations from the biotite Ž63–124 mm fraction. and Be Žin solution. vs. particle concentration Ž Cp . in pH 2 solution.

precluded the possibility to obtain reliable Na values. Also, because of the relatively high error in the albite dissolution data and the limited amounts of sorbed Be, no attempt was made here to calculate dissolution rates as presented below for biotite. It is important to mention that the amount of Be in biotite and albite ŽTable 1. which can be released upon dissolution is totally insignificant Žcompose a maximum of only 0.003 mmol ly1 . compared with the sorbed Be from solution. 3.5. The rate of biotite dissolution The kinetics of muscovite and phlogopite dissolution have indicated both linear Že.g., Lin and Clemency, 1981a,b., and parabolic Že.g., Acker and Bricker, 1992; Kalinowski and Schweda, 1996. behaviours. The data of biotite in this study indicate a nonlinear relationship between released cations and time; consequently, the rate of cation release is best described by the parabolic law dCrdt s k p ty1 r2

Ž 5.

where k p is the parabolic rate constant Žmol cmy2 sy1 r2 .. By integration, the concentration in solution C increases with the square root of time t, C s 2 k p t 1r2 q B

Ž 6.

where B is an integration constant. A plot of C

Al

Na

pH 2 solution (20 – 63 m m) 0.5 0.16 1 0.11 3 0.028 6 0.029 18 0.083 24 0.043 72 0.080 120 0.090 240 0.12 480 0.060

0.065 0.045 0.021 0.022 0.029 0.027 0.037 0.039 0.060 0.050

0.047 0.041 0.025 0.023 0.027 0.027 0.038 0.035 0.048 0.036

pH 2 (63 – 124 m m) 0.5 1 8 24 72 120 240 480

0.009 0.011 0.015 0.010 0.012 0.016 0.013 0.019

0.027 0.020 0.033 0.046 0.029 0.026 0.033 0.035

pH 4 solution (63 – 124 m m) 480 - 0.001

0.001

pH 6 solution (63 – 124 m m) 480 0.044

0.014

pH 7 solution (63 – 124 m m) 480 0.007

0.001

pH 9 solution (63 – 124 m m) 240 0.058

0.20

against t 1r2 produces straight lines having correlation coefficients Ž r . of 0.99 to 1.0, for Si and Al respectively of the two fractions in pH 2 solution ŽFig. 11a and b.. For Fe and Mg, the distributions with time fit a two-term Žearly and late. parabolic law ŽFig. 11c and d. having correlation coefficients above 0.94. The early term for the fine fraction laps is the first two days, and the corresponding term for

Fig. 9. AFM photographs showing the changes in surface textures of untreated biotite Ža. after reaction in pH 2 solution Žb. after 20 days Ž480 h. of experimental run. Observe the large difference in the Z scale of the two textures and the arrangement of dissolution pits Žalong the central part of Žb.., which is apparently induced by lattice defects.

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

222

Fig. 11. Rate of cation release from biotite in pH 2 solution and at a particle concentration of 2 g ly1 .

the coarse fraction is the first five days. Fe has a higher rate constant during the first two days, but the

release rate constants of Si and Al become higher at later stages ŽTable 9..

Table 9 Rate constant and rate of cations release from biotite in pH 2 solution and particle concentration of 2 g ly1 Cation

Grain size Žmm.

Rate constant k p Ž10y12 mol cmy2 sy1r2 .

Rate Žafter 20 days. Ž10y15 mol cmy2 sy1 .

Si

20–63 63–124 20–63 63–124

0–20 days 4.54 3.58 3.13 2.72

3.45 2.73 2.38 2.08

20–63

0–2 days 7.63

2–20 days 0.82

0.62

63–124

0–5 days 4.06

5–20 days 0.68

0.52

20–63

0–2 days 1.72

2–20 days 0.13

0.10

63–124

0–5 days 0.89

5–20 days 0.41

0.32

Al

Fe

Mg

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

223

4. Discussion In all the experimental runs, the amount of Be sorbed by biotite is apparently greater than that by albite ŽFigs. 1–3.. Several factors, including the crystalline structure of the mineral, pH of reacting solution and surface area of particles Žgrain size of particles and amounts of suspended particles. affect the distribution of Be between the solids and solution used in this study. 4.1. Biotite and albite dissolution and the effect on Be sorption By definition, the processes of sorption and dissolution occur at the mineral–solution interface Že.g., Aagaard and Helgeson, 1982; Carroll and Walther, 1990. and are strongly controlled by the available chemistry and specific surface area of minerals. The effect of surface chemistry is illustrated by the three minerals Žbiotite, albite and quartz. used in this study. In the pH range of 2–6 where Be is expected in a dominantly solute form, the most reactive mineral, biotite, sorbed the largest amount of Be followed by the less reactive albite whereas quartz showed no sorption whatsoever. Additionally, biotite possesses phyllosilicate structure, which permits, for a given grain size, a larger specific surface area than albite with a framework silicate structure. The specific surface area of biotite is about 21 and 110 times larger than albite for the two size fractions of 20–63 mm and 63–124 mm, respectively ŽTable 1.. This may partly explain the insignificant sorption of Be onto albite relative to biotite. Also, the easily leachable cations from the interlayer and octahedral layer of biotite relative to the framework of tetrahedral rings of albite and the easy formation of simple clay mineral structure Že.g., Si–Al sheets. or intermediate unstable phases, such as vermiculitic or kaolinitic layers upon alteration of biotite in acidic solutions ŽBanfield and Eggleton, 1988; Acker and Bricker, 1992; Kalinowski and Schweda, 1996; Malmsrom ¨ and Banwart, 1997. may enhance and control sorption of Be onto biotite grains. This behaviour is suggested by Be sorption ŽFig. 2., cation release ŽFig. 7. and release rate ŽFig. 11 and Table 9. and the normalized ratio of mole released cations to the mole sorbed Be ŽFig. 12.. While Be sorption and

Fig. 12. The percent ratio of mole released cations Žfrom biotite. and mole sorbed Be Žonto biotite. Ž Mi . relative to the starting moles of biotite and Be Ž Mi0 . used in the experiment of pH 2 solution.

release of Fe and Mg Žoctahedral-layer cations. reach about equilibrium after 10 days, the amounts of released Si and Al Žtetrahedral-layer cations. have not reached equilibrium with solution even after 20 experimental days. Also in spite of the varying release rate of cations ŽFig. 7., the sorption rate of Be remains rather constant ŽFig. 6 and Table 6.. The most likely explanations of these features are; Ž1. incorporation of Si and Al into neoformed Si–Al structures which deplete these cations from solution and consequently enhance both disequilibrium with the solution and the concentration of Fe and Mg during the first two experimental days; Ž2. Because of this process, there is less access to relatively easily detached cations from the octahedral and interlayer sites Ždominated by Fe–Mg, K, oxygens and OH ions bonding. and accordingly the Fe–Mg re-

224

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

lease and Be sorption reach steady state. The preliminary AFM data indicate some regularity of the etch pits as they stop penetrating along the 001 plane ŽFig. 9b.. The development of these etch pits Žshow˚ . at their ing a relief difference of about 50–100 A final stage resembles the tetrahedral Si–O–Si–O- or Al–O–Al–O-hexagonal and ditrigonal structures that are typical for mica Že.g., Bailey, 1980; Medina et al., 1984.. The use of relatively dilute acid solutions in this study could have mediated the sorption of Be onto biotite via a simple cation exchange process, probably Be 2q and BeOHq for Fe 2q, Mg 2q and Kq, without formation of complex ligands Že.g., Furrer and Stumm, 1986.. The SEM examination of the dissolution textures at pH 2 ŽFig. 8. suggests changes from rough and strongly etched surfaces to plane ones as the dissolution process proceeds to equilibrium. Although no attempt was made here to study in detail the time-dependence of these textural features, it seems that the dissolution involves: Ž1. an early stage controlled mainly by ultrafines and mechanically induced Žcrushing and sieving effects. surface irregularities, and Ž2. a later stage controlled mainly by the surface chemistry of the biotite grains. The general dissolution, at pH 2 to 9, behaviour ŽFig. 13a. and dissolution rate ŽFig. 13b. resemble trends reported for kaolinite ŽCarroll and Walther, 1990., muscovite ŽKnauss and Wolery, 1989. and biotite ŽAcker and Bricker, 1992., and confirm a similarity of phyllosilicate dissolution behaviour. The release rates of Si,

Al, Fe and Mg after 20 days range from 10y1 4.5 to 10y1 6 mol cmy2 sy1 ŽTable 9. and are comparable to the estimated rates for biotite alteration of 10y1 5 y 10y1 7 mol cmy2 sy1 reported by Velbel Ž1985. and Acker and Bricker Ž1992.. The larger amount of released Al compared with Si at pH 9 ŽFig. 13. may relate to the difference in Be and Si solubility, i.e. Si solubility increases with pH ŽDrever, 1982.. Thus, part of Si might be resorbed onto the Be-hydroxide precipitate at pH 9. Albite dissolution data have, as mentioned above, a large error range and thus will be briefly commented upon. According to data of other experiments Že.g., Chou and Wollast, 1985; Knauss and Wolery, 1989; Blum and Lasaga, 1991., the dissolution rate curves of albite and muscovite are very similar in acidic and alkaline pH. Our data, as shown by biotite dissolution ŽFig. 13., indicate a slightly different behaviour which most likely relates to the effect of Be activity in the solution, as mentioned above. At pH 2, Be is highly soluble and facilitates, together with Hq ions, the surface exchange Ždissolution. between solution and released cations. This process seems to have occurred in albite-bearing solution, as evidenced by the relative sorption of some Be onto albite. 4.2. Solution pH and particle size and concentration Beryllium exhibits only the q2 oxidation state and has rather simple hydrolysis products in aqueous

Fig. 13. The concentration Ža. and rate Žb. of released cations from biotite Ž63–124 mm fraction. vs. pH and at particle concentration of 2 g ly1 and after 10 days Ž240 h. of experimental run. F is the molar ratio of released cations normalized to the original molar ratio of cations per unit biotite formula.

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

solution which are mainly controlled by Be 2q, BeOHq and BeŽOH. 2-solute at the range of solution pH used in this study, although some weaker chloride complexes may occur ŽBaes and Mesmer, 1976; Hinz et al., 1986.. Thus, the most likely predominant form of soluble Be, which is available for sorption, is as Be 2q and BeOHq at solution pH F 6 ŽFig. 14.. As the pH value increases, there is formation of BeŽOH. 2-solid , which has very low solubility Žsolubility product 10y2 1 . and precipitates very rapidly. This strong solubility controlled behaviour is the most likely reason for obtaining rather similar K d values at pH )f 6 to )f 12, by direct precipitation, irrespective of the chemical and physical nature of the suspended particle and time. For example, You et al. Ž1989. studied 7 Be distribution between solids Žillite, kaolinite and river mud. and river water and their K d vs. pH plot showed a trend for K d to increase as pH increases from 0 to 6, and then to be rather constant Žabout 2 = 10 5 ml gy1 . between pH ) 6 and - 12. Similar behaviour was also reported by Brown et al. Ž1992. and You et al. Ž1994.. Our calculation of K d at pH ) 6 and - 10 Žthough not valid. indicates a trend similar to the speciation of Be ŽFig. 14. which suggests control of BeŽOH. 2 precipitate at pH between 8 and 10. K d values obtained at pH above seven are also independent of time because equilibrium occurs rather rapidly Žwithin a few hours., as

Fig. 14. The relation between K d of Be Žcorrected values for pH 6 and 7 solutions, Table 4. for biotite and the percentages of three important speciation forms of Be at variable pH. The filled and empty rings are the 20–63 and 63–124 mm grain size fractions respectively. The K d values for pH 7 and 9, although calculated and plotted, are just used for visual comparison and they should not be valid Žsee text for details..

225

suggested by our data at pH 7. The possibility of saturation of available sorption sites and a consequent precipitation at lower pH due to the relatively high concentration of Be in our experiment does not seem to be the case. This is because a behaviour similar to our data ŽFig. 14. was also demonstrated by the natural distribution of Be Že.g., You et al., 1989; Brown et al., 1992.. Although we have, for the sake of comparison with published literature data, used mainly the weight normalized K d , the surface area normalized K ds should be more representative to overcome the problem of grain size variability. Theoretically, it is expected that a similar K ds value should be obtained for all grain sizes. This, however, seems to be partly the case for biotite, but not for albite ŽTables 4 and 5.. The K ds values for albite show large variations between the two grain sizes and, as mentioned above, it includes a large measurement error. Although the K ds of albite should be interpreted with caution, the relatively several times higher values than for biotite suggest some sorption of Be. Also, it is worth mentioning that the surface area of both minerals should have successively been changed during the experiment, but because of measurement difficulties Žaggregation and fragmentation of grains. it was not possible to obtain reliable surface area data for postexperiment fractions. The values of K d at pH 7 for both biotite and albite ŽTable 5. include mainly direct precipitation of Be as a hydroxide and precipitation has also partly contributed to the calculated K d values at pH 6 which closely follow the speciation behaviour of Be ŽFig. 14.. A theoretical and rather rough approach was used here to separate the component of precipitation at the pH values of 6 and 7 to be able to calculate a most likely sorption effect. We have simply subtracted the percentage of BeŽOH. 2-solid that can be removed by precipitation from the total Be sorbed on biotite and albite. This gives corrected K d values, K dcorr ŽTables 4 and 5. at pH 6 and 7. For pH 7 the K dcorr values have a large error as they form only about 3% of the total Žuncorrected. K d , and we suggest that K d calculation at pH 7 is improper or not valid. However, we are interested in the relative Žbetween biotite and albite. rather than the absolute magnitude of K d , and a difference exists for the K dcorr values at pH 6 and 7. Further-

226

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

more, the much higher values of K dcorr for pH 6 relative to pH 2 is indicative of a dominantly sorption-controlled rather than precipitation-controlled process at pH 6. The results of this study show that the amount of sorbed Be increases with an increasing concentration of suspended particles at pH 2 and pH 6 ŽFig. 3 and Table 4.. This trend can be explained by an increase of the total surface area of particles in solution. On the other hand, the K d of Be decreases with increasing concentration of suspended particles ŽFig. 5.. Such results were also reported by Hawley et al. Ž1986., Olsen et al. Ž1986. and You et al. Ž1989. and their data showed considerable scatter. Also, Brown et al. Ž1992. failed to find a relationship between suspended particle concentration and Be in their study of some river basins. This behaviour of K dparticle concentration is difficult to explain because according to the definition of K d ŽEq. Ž1.. there should be one K d value at any pH irrespective of the concentration of the suspended particles. A possible, though speculative, explanation is particle aggregation increasing at higher suspended particle concentration, thus the effective surface area per gram for adsorption is reduced and K d is lowered ŽLi et al., 1984.. It is observed that under the same pH conditions, the release of cations from biotite and sorption of Be increases with increasing concentration of suspended particles ŽFig. 10.. The trend of Be sorption follows that of Fe and Mg release in a way whereby the difference is small at 1 and 2 g ly1 , when compared with Si and Al trends. A possible explanation of these features is balance of a negative charge, created through release of octahedralrinterlayer cations, by sorption of Be onto biotite. As discussed above, there are some differences in the K d values of Be for the two grain size fractions used in the experiment ŽTable 5.. The plot of K d on a log scale minimizes the difference and suggests that size variability of the grains may effect K d distribution, particularly for biotite. The large uncertainty in the measurements of both the surface area of the particles and the concentration of sorbed Be ŽTables 1 and 5. for albite, makes evaluation of grain size effect doubtful. It is also clear that the difference between the K d of the two grain sizes used becomes much larger at pH 6 and even more at pH 7 which,

as we mentioned above, is related to the component of precipitation at these pH values. The grain size and specific surface area effects might also be a cause of the relatively high K d values of illite and kaolinite Žclay size particles. at pH - 6 reported by You et al. Ž1989. compared with the K d of biotite in this study. Similarly, the wide spread of the K d vs. suspended particle concentration data of Hawley et al. Ž1986. and Olsen et al. Ž1986. may partly arise from variations in grain size of the sediments. 4.3. Be in continental aquatic systems Although the concentrations of 7 Be, 9 Be and 10 Be in continental aquatic systems Žmainly rivers and lakes. vary widely, being up to 1 mg ly1 Ž9 Be. and to a few thousands atoms ly1 Ž7 Be and 10 Be., their sorption behaviour seems to be similar, as evidenced by both our own and other experimental work and data from natural systems Že.g., Hawley et al., 1986; You et al., 1989; Brown et al., 1992.. However, the short half-life of 7 Be Ž53.4 days. puts a limit on the availability when equilibrium is considered in calculation of distribution coefficient as shown by several studies Že.g., Nyffeler et al., 1984; Hawley et al., 1986.. The sorption of stable 9 Be and the radionuclide 10 Be Žhalf-life 1.5 Ma. in continental aquatic systems may be equally treated once these isotopes occur in soluble forms, irrespective of the source. The pH of solution is then an important parameter that controls Be-solubility and sorption. Furthermore, available data indicate that the natural concentrations 2y of Cly, NOy 3 and SO4 , polynuclear hydroxy-complexes and organic complexes Žlike citrate-4 and salicylate-2. in aquatic systems have no significant effect on Be solubility ŽFurrer and Stumm, 1986; McComish and Ong, 1988 and references therein.. Also, the change in oxidation conditions does not affect the solubility of Be, unless it is accompanied by a pH change, as is the case in sulphide-oxidation. However, even there the Eh should be below y1.85 V Žstandard-state half cell potential. at 258C Žwhich is uncommon in continental aquatic systems. to allow for the transformation of Be 2q to Be-sulphide solids. Therefore, the formation of a stable BeŽOH. 2-solid is apparently the main reason for the decreasing content of Be in continental aquatic systems as pH approaches 7.

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

This case has been well illustrated by the work of Brown et al. Ž1992. on the distribution of Be in the Orinoco Basin, Venezuela. In cases where the pH remains below 7, sorption of Be onto sediment particles was an effective sink. Thus the sensitive influence of pH on Be solubility at pH values 5–8, which is a common variation range in natural aquatic systems, may greatly contribute to the variation in Be budget over time. The data of this work indicate that mineral composition and specific surface area are important parameters in such cases. Biotite Žand other phyllosilicates. has a stronger sorption capacity for Be than albite Žand other Na–Ca–K feldspars., which is an important aspect during the study of Be distribution in continental and near-shelf environments. For example, erosion andror occurrence of biotite Žand several other phyllosilicates.-rich materials Žacid igneous rocks and sedimentary rocks. will furnish a strong Be-sorbant in an aquatic system. The decreasing distribution coefficient Ž K d . values with increasing suspended particle concentrations ŽFig. 5. indicates that sorption of Be in lakes and rivers is inversely related to the amount of suspended particles, also observed by You et al. Ž1989. for some rivers in Taiwan. This relationship may result in higher Be concentrations during slow sedimentation rate episodes, due to lower concentration of suspended particles Žhigh surface area., relative to high sedimentation rate ones.

5. Conclusions Ž1. Be is strongly sorbed by biotite relative to albite and the Be sorption by quartz was negligible at the same pH, grain size and suspended particle concentrations. Ž2. At pH F 6, the distribution of Be between solution and solids is related to sorption but at pH ) 6, the solute concentration is strongly controlled by solubility of BeŽOH. 2-solid . The distribution coefficient Ž K d ml gy1 . for biotite is up to 30 times higher than for albite in pH 2, 4 and 6 solutions and with a suspended particle concentration of 2.0 g ly1 . The K d increases with decreasing suspended particle

227

concentration Žfrom 0.2 to 2.0 g ly1 . for both minerals. The rate of Be sorbed onto biotite ranges from 0.8 to 1.0 = 10y1 1 mol cmy2 sy1 in pH 2 and 6 solutions, respectively. The K d –pH trend of Be sorbed onto biotite is generally similar to those of illite and kaolinite ŽYou et al., 1989., although the latter show about 2 orders of magnitude higher values at pH ) 5, most likely due to the use of lower suspended particle concentrations and finer Žclay size. particle sizes than those used in our study. Ž3. The surface area-normalized K ds shows a trend similar to the weight normalized K d with respect to grain size and solution pH. These data suggest that grains size variability may affect K d distribution, particularly for biotite. It is also clear that the difference between the K d of the two grain sizes used becomes much larger at pH 6 and even more at pH 7, which as we mentioned above was related to the component of precipitation at these pH values. The K ds of albite, however, becomes higher than biotite, but because of the large error in both Be concentration and surface area of albite, the results should be interpreted with caution. Ž4. The concentrations of Si, Al, Fe and Mg released from biotite in pH 2 solution vs. time fit the parabolic rate law. The rates of release after 20 days range from 10y1 4.5 to 10y1 6 mol cmy2 sy1 and are comparable with rates reported by, e.g. Velbel Ž1985. and Acker and Bricker Ž1992.. Biotite dissolution apparently enhances and controls the sorption of Be, which most likely relates to availability of compatible exchangeable cation sites within the etched surfaces. The sorption of Be onto biotite and the Si, Al, Fe and Mg release from biotite in pH 2 solution show an increasing trend with increasing suspended particle concentration. Ž5. The pH of aquatic systems strongly controls mobility and transport of soluble Be and, consequently, precipitation as BeŽOH. 2-solid may become a significant mechanism for removal of Be from water bodies at pH ) 6. At pH - 6, chemistry and specific surface area of the suspended particles control the distribution of Be. This means that the use of Be isotopes for environmental, dating and petrogenetic studies is constrained by sediment–water interaction and a detailed understanding of a time-related environmental change of both the water body and the sediment is important.

228

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229

Acknowledgements Financial support for this work was received from the The Tandem Laboratory ŽAMS-Group., the Swedish Natural Science Research Council ŽNFR. and the Knut and Alice Wallenberg Foundation. XRD and SEM were carried out at the Institute of Earth Sciences, Uppsala University. We thank Arjan Quist for the help with AFM at the Institute of Ion Physics, Uppsala University. Constructive comments ¨ were provided by Orjan Amcoff, William M. Murphy, Eugene Ilton, B.E. Kalinowski and an anonymous reviewer. [SB]

References Aagaard, P., Helgeson, H.C., 1982. Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solutions: I. Theoretical considerations. Am. J. Sci. 282, 237– 285. Acker, J.G., Bricker, O.P., 1992. The influence of pH on biotite dissolution and alteration kinetics at low temperature. Geochim. Cosmochim. Acta 56, 3073–3092. Aldahan, A.A., Morad, S., 1986. Chemistry of detrital biotites and their phyllosilicate intergrowths in sandstones. Clays Clay Minerals 34, 539–548. Aldahan, A.A., Possnert, G., Gard, G., 1994. 10 Be in two sediment section from the North Atlantic and chronological implications for the late Quaternary. Nues. Jahr. Geol. Palaont. H. ¨ 7, 418–433. Aldahan, A.A., Possnert, G., Johnsen, S.J., Clausen, H.B., Isaksson, E., Karlen, ´ W., 1995. 10 Be and the 11-year solar cycle in ice records covering last 60 years. Annales Geophysicae 13, 422. Aldahan, A.A., Shi Ning, Possnert, G., Backman, J., Bostrom, ¨ K., 1997. Be-10 records from sediments of the Arctic Ocean covering the past 350 ka. Marine Geology 144, 147–162. Baes, Jr., C.F., Mesmer, R.E., 1976. The Hydrolysis of Cations, Wiley, New York. Bailey, S.W., 1980. Structures of layer silicates. In: Brindley, G.W., Brown, G. ŽEds.., Crystal Structures of Clay Minerals and their X-ray Identification. Mineralogical Society, Spottiswoode Ballantyne, London, pp. 2–115. Banfield, J.F., Eggleton, R.A., 1988. Transmission electron microscope study of biotite weathering. Clays Clay Minerals 36, 47–60. Beer, J., Blinov, A., Bonani, G., Finkel, R.C., Hofmann, H.J., Lehmann, B., Oeschger, H., Sigg, A., Suter, M., Wolfli, W., ¨ 1990. Use of 10 Be in polar ice to trace the 11-year cycle of solar activity. Nature 347, 164–166. Birkett, J.D., Bodek, I., Glazer, A.E., Grain, C.F., Hayes, D., Lerman, A., Lindsay, D.B., Loreti, Ch., Ong, J.H., 1988.

Description of individual processes. In: Bodek, I., Lyman, W., Reehl, W., Rosenblatt, D. ŽEds.., Environmental Inorganic Chemistry. Pergamon, New York, pp. 2.12-25–2.12-26. Blum, A.E., Lasaga, A.C., 1991. The role of surface speciation in the dissolution of albite. Geochim. Cosmochim. Acta 55, 2193–2201. Bourles, ´ D.L., Raisbeck, G.M., Yiou, F., 1989. 10 Be and 9 Be in marine sediments and their potential for dating. Geochim. Cosmochim. Acta 53, 443–452. Brook, E.D., Nesje, A., Lehman, S., Raisbeck, G., Yiou, F., 1996. Cosmogenic nuclide exposure ages along a vertical transect in western Norway: implications for the height of Fennoscandian ice sheet. Geology 24, 207–210. Brown, L., Sacks, I.S., Tera, F., Klein, J., Middleton, R., 1981. Beryllium-10 in continental sediments. Earth Planet. Sci. Lett. 55, 370–376. Brown, E.T., Edmond, J.M., Raisbeck, G.M., Bourles, ´ D.L., Yiou, F., Measure, Ch., 1992. Beryllium isotope geochemistry in tropical river basins. Geochim. Cosmochim. Acta 56, 1607– 1624. Carroll, S.A., Walther, J.V., 1990. Kaolinite dissolution at 258, 608, and 808C. Am. J. Sci. 290, 797–810. Chou, L., Wollast, R., 1985. Steady-state kinetics and dissolution mechanisms of albite. Am. J. Sci. 285, 963–993. Dibb, J., Talbot, R., Gregory, G., 1992. Beryllium-7 and lead 210 in the western Hemisphere Arctic atmosphere: observations from three recent aircraft-based sampling programs. J. Geophys. Res. 97, 16709–16715. Drever, J.I., 1982. The Geochemistry of Natural Waters. Prentice-Hall, Englewood Cliffs, NJ, 388 pp. Furrer, G., Stumm, W., 1986. The coordination chemistry of weathering: I. Dissolution kinetics of d-Al 2 O 3 and BeO. Geochim. Cosmochim. Acta 50, 1847–1860. Gosse, J.C., Klein, J., Evenson, E., Lawn, B., Middleton, R., 1995. Beryllium-10 dating of the duration and retreat of the last Pinedale glacial sequence. Science 268, 1329–1333. Gu, Z.Y., Lal, D., Liu, T.S., Southon, J., Caffee, M.W., Guo, Z.T., Chen, M.Y., 1996. Five million years 10 Be record in Chinese loess and red-clay: climate and weathering relationships. Earth Planet. Sci. Lett. 144, 273–278. Hawley, N., Robbins, J.A., Eadie, B.J., 1986. The partitioning of beryllium in fresh water. Geochim. Cosmochim. Acta 50, 1127–1131. Hinz, I., Koeber, K., Kreuzbichler, I., Kuhn, P., 1986. Be. In: Kugle, H.K. ŽEd.., Gmelin Handbook of Inorganic Chemistry, Supplement Vol. A1. Springer-Verlag, Berlin, pp. 292–299. Hofmann, H.J., Beer, J., Bonani, G., Raman, H.R., von Gunten, S., Suter, M., Walker, R.L., Wolfli, W., Zimmermann, D., ¨ 1987. 10 Be: half-life and A.M.S. standards. Nucl. Instr. Meth. Phys. Res. B 29, 32–36. Kalinowski, B.E., Schweda, P., 1996. Kinetics of muscovite, phlogopite and biotite dissolution and alteration at pH 1–4, room temperature. Geochim. Cosmochim. Acta 60, 367–385. Knies, D.L., Elmore, D., Sharma, P., Vogt, S., Li, R., Lipschutz, M.E., Petty, G., Farrel, J., Monaghan, M.C., Fritz, S., Agee, E., 1994. 7 Be,10 Be and 36 Cl in precipitation. Nucl. Instr. Meth. Phys. Res. B 92, 340–344.

A. Aldahan et al.r Chemical Geology 156 (1999) 209–229 Knauss, K.G., Wolery, T.J., 1989. Muscovite dissolution kinetics as a function of pH and time at 708C. Geochim. Cosmochim. Acta 53, 1493–1501. Ku, T.L., Southon, J.R., Vogel, J.S., Liang, Z.C., Kusakabe, K., Nelson, D.E., 1985. 10 Be distribution in Deep-Sea Drilling Project site 578 sediments studied by accelerator mass spectrometry. Init. Repts. DSDP LXXXVI, 539–546. Li, Y.-H., Burkhardt, L., Bucholta, M., O’Hara, P., Santschi, P.H., 1984. Partition of radiotracers between suspended particles and sea water. Geochem. Cosmochim. Acta 48, 2011–2019. Lin, F.C., Clemency, C.V., 1981a. The kinetics of dissolution of muscovites at 258C and 1 atm CO2 partial pressure. Geochim. Cosmochim. Acta 45, 571–576. Lin, F.C., Clemency, C.V., 1981b. Dissolution kinetics of phlogopite: I. Closed system. Clays Clay Minerals 29, 101–106. Loreti, Ch., 1988. Chemical composition of the environment. In: Bodek, I., Lyman, W., Reehl, W., Rosenblatt, D. ŽEds.., Environmental Inorganic Chemistry. Pergamon, New York, pp. B1–B18. Malmsrom, ¨ M., Banwart, S., 1997. Biotite dissolution at 258C: the pH dependence of dissolution rate stoichiometry. Geochim. Cosmochim. Acta 61, 2779–2799. Mangini, A., Segal, M., Bonani, G., Hofmann, H.J., Morenzoni, E., Nessi, M., Suter, M., Wolfli, W., Turekian, K.K., 1984. Mass spectrometric 10 Be dating of deep-sea sediments applying the Zurich tandem accelerator. Nucl. Instr. Meth. Phys. Res. B 5, 353–358. McComish, M.F., Ong, H.J., 1988. Trace metals, chemical composition of the environment. In: Bodek, I., Lyman, W., Reehl, W., Rosenblatt, D. ŽEds.., Environmental Inorganic Chemistry. Pergamon, New York, pp. 7.4-1–7.4-6. Medina, J.A., Morante, M., Leguey, S., Tornero, J., 1984. Some observations on the relationship between etch-pit and structure in biotite. Clay Minerals 20, 263–271. Monaghan, M.C., Mckean, J., Dietrich, W., Klein, J., 1992. 10 Be chronology of bedrock-to-soil conversion rates. Earth Planet. Sci. Lett. 111, 483–492. Nyffeler, U.P., Li, Y.H., Santschi, P.H., 1984. A kinetic approach to describe trace-element distribution between particles and

229

solution in natural aquatic systems. Geochim. Cosmochim. Acta 48, 1513–1522. Olsen, C.R., Larsen, I.L., Lowey, P.D., Cutshall, N.H., Nichols, M.M., 1986. Geochemistry and deposition of 7 Be in river estuarine and coastal waters. J. Geophys. Res. 91, 896–980. Pavich, M.J., Vidic, N., 1993. Application of paleomagnetic and 10 Be analyses to chronostratigraphy of alpine glacio-fluvial terraces, Sava river valley, Slovenia. Geophys. Monogr. 78, 263–275. Possnert, G., Aldahan, A.A., Vintersved, I., 1995. Be-7 and Be-10 activity of surface air over Sweden and implication to short term climatic changes. Annales Geophysicae 13, 437. Raisbeck, G.M., Yiou, F., Fruneau, M., Loiseaux, J.M., Guichard, F., 1980. 10 Be concentration and residence time in the deep ocean. Earth Planet. Sci. Lett. 51, 275–278. Segl, M., Mangini, A., Bonani, G., Hofmann, H.J., Morenzoni, E., Nessi, M., Suter, M., Wolfli, W., 1984. 10 Be dating of the ¨ inner structure of Mn-encrustations applying the Zurich tandem accelerator. Nucl. Instr. Meth. Phys. Res. B 5, 359–364. Shen, C.D., Beer, J., Tungsheng, L., Oeschger, H., Bonani, G., Suter, M., Wolfli, W., 1992. 10 Be in Chinese Loess. Earth ¨ Planet. Sci. Lett. 109, 169–177. Shi Ning, Aldahan, A.A., Haiping, Y., Possnert, G., Konigsson, ¨ L.-K., 1994. 10 Be in continental sediments from north China: probing into the last 5.4 Ma. Quaternary Geochronology ŽQuaternary Science Review. 13, 127–136. Skilleter, D.N., 1990. To be or not to be—the story of beryllium toxicity. Chemistry, pp. 26–30. Velbel, M.A., 1985. Geochemical mass balance and weathering rates in forested watersheds of the southern Blue Ridge. Am. J. Sci. 285, 904–930. Weast, R.C., Melvin, J., 1981. CRC Handbook of Chemistry and Physics. CRC Press, FL. You, C.-F., Lee, T., Li, Y.H., 1989. The partition of Be between soil and water. Chemical Geology 77, 105–118. You, C.-F., Morris, J.D., Gieskes, J.M., Rosenbauer, R., Zheng, S.H., Xu, X., Ku, T.L., Bischoff, L.J., 1994. Mobilization of beryllium in the sedimentary column at convergent margins. Geochim. Cosmochim. Acta 58, 4887–4897.