Excess222Rn and the benthic boundary layer in the western and southern Indian Ocean

We present 9 bottom²²²Rn profiles measured from the western and southern Indian Ocean during the 1977–1978 GEOSECS expedition. These profiles can be grouped into three cypes: one-layer, two-layer, and irregular types. The one-layer profiles with quasi-exponential distributions allow one to estimate the apparent vertical eddy diffusivity,K_v, with a simple model. The two-layer profiles show that there is a benthic boundary layer of the order of 50–100 m in which the excess²²²Rn distribution shows a vertical gradient much smaller than that of the layer immediately above. Within the boundary layer, the STD potential temperature (θ) and density(σ₄) profiles are practically constant, and theK_v values are of the order of 1000 cm²/s. The STD profiles for the water column above the boundary layer show gradients of increasing stability, and theK_v values are of the order of 100 cm²/s. Modeling of the Rn data in the water column above the boundary layer indicates that there is a transition layer which effectively reduces the penetration of excess Rn from the benthic boundary layer into the upper layer.Sarmiento et al. [10] have shown that the buoyancy gradient or stability is inversely correlated with the apparent vertical eddy diffusivity, and the resulting buoyancy flux is fairly uniform, ranging from 1 to 14 × 10^?6 cm²/s³ in the Atlantic and Pacific Oceans. However, Sarmiento et al. [11] show that a much higher buoyancy flux is associated with an intensified flow of the bottom water through a passage. In the Indian Ocean basins, we have found that the buoyancy flux has a comparable range (3–14 × 10^?6 cm²/s³), except for a couple of stations where both stability and apparent vertical diffusivity are higher, resulting in a much higher buoyancy flux, probably indicative of rapid bottom water flow.     

Excess bottom222Rn profiles and their implications in the northwestern Pacific Ocean

Vertical profiles of excess bottom²²²Rn and potential temperature were measured at 23 stations in the northwestern Pacific Ocean. The Rn profiles were classified into the following three types: quasi-exponential (type E), benthic boundary layer (type B), and horizontally disturbed (type H). The ratio among types E, B and H was approximately 2 : 3 : 1.An apparent vertical eddy diffusivity (K) was calculated by applying a one-dimensional diffusion model to the Rn profiles of types E and B. Type E had K values ranging from 15 to 180 cm² s^?1 (average: 70 cm² s^?1). As to type B, K values for the benthic boundary layer (4.5–260 cm² s^?1, average: 120 cm² s^?1) were always more than an order of magnitude larger than those for the upper layer (0.2–35 cm² s^?1, average: 7 cm² s^?1), indicating more active vertical mixing in the benthic boundary layer than in the upper layer.Rn profiles were measured in regions where the bottom topography is known. It was verified that the occurrence of type H related closely with local bottom topographic features accompanied by lateral transient supply of Rn-rich or Rn-poor water.A couple of Rn profiles at the same location, measured at time intervals of several years, were compared with each other for three locations. The general characteristics of Rn profiles were shown to remain unaltered with time, while the fine structure of Rn profiles may have short-term variations caused by local bottom topography and fluctuations of bottom current as indicated in type H.     

Excess 3He in deep water on the East Pacific Rise

Helium isotope measurements show that water on the crest and flanks of the East Pacific Rise has the highest enrichment in ³He so far observed in the oceans; the ³He/⁴He ratio anomaly relative to atmospheric helium is + 32% at the mid-depth maximum in the profiles. The corresponding ³He solubility anomaly relative to saturation with atmospheric helium is +50%. These data indicate that active sea-floor spreading sites on the crests of the mid-ocean rises are the sources of primordial helium injected into the ocean from the earth's interior. The ³He/⁴He ratio in this flux is approximately 1.6 × 10^?5, about 11 times the atmospheric ratio of 1.4 × 10^?6. The total flux of ³He into the atmosphere is 4.6 atoms cm^?2 earth-surface sec^?1, most of which (4.0 atoms cm^?2 sec^?1) is supplied by the oceanic flux. The corresponding atmospheric residence time for ³He is 10⁶ years, which, within the large uncertainties of supply and demand (thermal escape), is consistent with the requirement for a steady state.     

Ion microprobe studies of water in silicate melts. Concentration-dependent water diffusion in obsidian

The ion microprobe at Johnson Space Center has been calibrated for in situ water determinations on a 10-μm scale over the range 0.2 wt.% H₂O to 1.8, 6.8, and 3.7 wt.%, for basaltic, albitic, and rhyolitic glasses, respectively. The basalt glass calibration curve differs substantially from those of albite and rhyolite glasses, indicating a need to carefully match composition and/or melt structure between H₂O standards and unknowns.A value for the diffusivity of water as a function of concentration and time has been calculated from water diffusion profiles measured in rhyolite glasses prepared at 850°C and 700 barsP_t(H₂O) [1]. Transient diffusion into a semi-infinite medium is described by the equation:?(φ/2)?¸/?φ=?(D_w?¸/?φ)/?φ #x003B8;=1, φ=0, θ→ 0, θ→∞, wherex =distance from the cylinder edge,t =time,C₀ =initial concentration,C_s =concentration at the edge,C =concentration at x,θ = C ? C₀/C_s ? C₀,φ = x/t^1/2, andD_w =diffusivity of water. An iterative technique has been used to calculate solutions to the diffusion equation as a function ofD_w [2]. Comparison of these solutions with the ion probe data indicate that, for0.2wt.% ≤ C ≤ 3.7wt.%H₂O,D_w can be described by an exponential function of θ, of the formD_w = D₀exp(bθ), withD₀ (i.e.,D_w at 0.2%) = (0.8?2.2) × 10^?8 cm²/s and2 ≤ b ≤ 4.     

Elasticity of polycrystalline stishovite

Ultrasonic data for the velocities of SiO₂-stishovite have been determined as a function of pressure to 10 kbar at room temperature for polycrystalline specimens hot-pressed at pressures P = 120kbar and temperatures T = 900°C. These cylindrical specimens are 2 mm in diameter and 0.9–1.4 mm long and have a grain size less than 10 μm. Compressional and shear wave velocities were measured both parallel and perpendicular to the axis of pressing and were found to be isotropic at 10 kbar with ν_p = 11.0 ± 0.2km/sec andν_s = 6.9 ± 0.3km/sec; this shear velocit is substantially higher than that of Mizutani et al. (1972) perhaps due to the presence of crack orientations in their specimen which affected ν_s but not ν_p. The Murnaghan P-V trajectories calculated from the ultrasonic data [bulk modulus K_s = 2.5 ± 0.3Mbar and assuming (?K_s/?P)_T = 6 ± 2] are consistent with recent hydrostatic compression data and with the shock wave compression data above 600 kbar. The combined evidence from the data of the ultrasonic and hydrostatic compression techniques suggests that the most probable value of the bulk modulus of stishovite at zero pressure is close to the upper limit of the uncertainty of our ultrasonically determined value, K₀ = 2.7?2.8Mbar. Elasticity data for rutile-type oxides are not compatible with normal K_s-V₀ systematics perhaps due to the neglect of non-central forces in the lattice model. These new stishovite data would make it impossible to satisfy the elasticity-density data of the lower mantle using an oxide mixture with either olivine or pyroxene stoichiometry.     

Velocity-density systematics,mean atomic weight,and the interior of the moon

Mean atomic weight profiles for the lunar mantle have been calculated from velocity-density systematic relations using lunar density and seismic velocity models. Despite large variability among the models, the calculation including Poisson's ratio yields a range of mean atomic weight values between 22 and 23 g mol^?1 below 150 km. A similar calculation for the Earth's mantle produces a mean atomic weight of 21.1 ±0.4 g mol^?1. This suggests that the Moon cannot be derived directly from the Earth's mantle, or that it has had a differentiation history different from the Earth's. The lunar $\text{m}\text{'}\text{s}$ require an Fe mole fraction between 0.25 and 0.33 for a pure olivine mantle, or between 0.33 and 0.45 for pure pyroxene.The present profiles are 0.5–3.0 g mol^?1 higher than those calculated from lunar compositional models based on lunar rock compositions and petrology and assumed lunar histories, indicating inadequacies in either the seismic or compositional models, or in both. The mean atomic weight approach provides a method of comparing the consistency of seismic and compositional models of planetary interiors.     

Rare earth element systematics of hydrous liquids from partial melting of basaltic eclogite a re-evaluation

The origin of orogenic andesitic magmas is tested by calculations of REE fractionation in hydrous melts derived from partial melting of subducted ocean basalt in eclogite facies. New data on the subsolidus phase proportions of basaltic eclogite, the enrichment of LREE in altered ocean basalts, and experimentally determined REE partition coefficients (K_D's) between garnet and melt have been included in trace element fractionation equations. Non-modal melting of phases combined with variation inK_D's during melting is a unique feature of these calculations.Variation ofK_D, melting proportions, initial proportion of subsolidus phases, degree of melting, and initial REE concentrations yield a wide range of input parameters that produce REE profiles in partial melts of basaltic eclogite matching REE profiles of some orogenic andesites. The positive correlation of REE concentration with silica content for many andesitic suites can be accounted for by non-modal melting if quartz (or a similar phase with low REEK_D values) melts at a high melting proportion and garnet melts at a low melting proportion during the first stages of fusion. However, no mineralogic fractionation scheme can account for REE/silica systematics if REEK_D values are linearly decreasing with increasing melting. Earlier workers who have used similar calculations to discredit the eclogite fractionation model have set overly strict, and sometimes incorrect, constraints concerning the range in REEK_D values for garnet, the subsolidus proportions of phases in basaltic eclogite, and the relative concentrations of REE in subducted ocean crust undergoing partial melting.     

Meridional distribution of226Ra in the eastern Pacific along GEOSECS cruise tracks

We present the distribution of²²⁶Ra in eight vertical profiles from the eastern Pacific. The profiles are located along a meridional trend near 125°W, from 43°S to 29°N. Surface²²⁶Ra concentrations are about 7 dpm/100 kg, except for the two stations south of 30°S where the higher values are due to the Antarctic influence. Deep waters show a distinctive south-to-north increase in the²²⁶Ra content, from about 26 to 41 dpm/100 kg near the bottom. Unlike in the Atlantic and Antarctic Oceans, the effect of²²⁶Ra injection from bottom sediments is clearly discernible in the area. The presence of this primary²²⁶Ra can be traced up to at least 1–1.5 km above the ocean floor, making this part of the sea bed among the strongest source regions for the oceanic²²⁶Ra. Numerical solutions of a two-dimensional vertical advection-diffusion model applied to the deep (1.2–4 km)²²⁶Ra data give the following set of best fits: upwelling velocity(V_z) = 3.5m/yr, vertical eddy diffusivity(K_z) = 0.6cm²/s, horizontal (north-south) eddy diffusivity(K_y) = 1 × 10⁷cm²/s, and water-column regeneration flux of²²⁶Ra(J) = 3.3 × 10^?5dpmkg^?1yr^?1 as an upper limit. These parametric values are in general agreement with one-dimensional (vertical) model fits for the Ra-Ba system. However, consideration of²²⁶Ra balance leads us to suspect the appropriateness of describing the vertical exchange processes in the eastern Pacific with constantV_z and K_z. If future modeling is attempted, it may be preferable to treat the area as a diffusion-dominant mixing regime with depth-dependent diffusivities.     

Determination of the lifetime of molecules O 2 + and estimation of the flux of penetrating electrons generating a cloud of excess concentration of O 2 + in the ionosphere at altitudes above 220 km

The occurrence of anomalous (nonthermal) profiles of green emission of oxygen atoms detected with a Fabry-Perot spectrometer in auroras with the effect of a rapid decrease in the intensity of the wings of their dissociative component has been investigated. Based on an analysis of these measured profiles, it has been found that the characteristic time of recombination of a molecular oxygen ion at altitudes of 200–400 km is about 5–7 s. It appears that these molecular ions occur in a horizontally limited region of the auroral ionosphere as a result of ionization by a space localized flux of soft electrons with energies of 0.2–0.4 keV penetrating up to altitudes of 200 km. The estimation of the electron flux produces a value of 10¹⁰–10¹³ electrons cm^?2 s^?1. They generate the excess concentration n(O ₂ ⁺ ) ~ 5.6 × 10⁵ cm^?3.     

High-speed correction factor to the O+-O resonance charge exchange collision frequency

The high-speed correction factor to the O⁺-O collision frequency, resulting from drift velocities between ions and neutrals, is calculated by solving the integral expression in this factor both numerically and analytically. Although the analytic solution is valid for either small or large drift velocities between ions and neutrals, for temperatures of interest and all drift velocities considered, agreement is found between analytic and detailed numerical integration results within less than 1% error. Let T _r designate the average of the ion and neutral temperatures in K, and u=v _d /<alpha>, where v _d is the relative drift velocity in cm s^?1, and <alpha>=4.56×10³\sqrtT _r cm s^?1 is the thermal velocity of the O⁺-O system. Then, as u ranges from 0 to 2, the correction factor multiplying the collision frequency increases monotonically from 1 to about 1.5. An interesting result emerging from this calculation is that the correction factor for temperatures of aeronomical interest is to a good approximation independent of the temperature, depending only on the scaled velocity u.     

MELIMEX,an experimental heavy metal pollution study: Vertical mixing in a large limno-corral

In a limno-corral (diameter 12 m, depth to sediments 10 m), located in Baldeggersee (Switzerland), vertical mixing has been measured during more than one year and compared to the conditions in the open lake (maximum depth 65 m, surface area 5.3 km²). The temperature method by McEwen and Hutchinson yields K_z values between 5×10⁻² cm²s⁻¹ at the upper boundary of the thermocline and 2×10⁻³ cm²s⁻¹ at the bottom, a value near the molecular diffusion of heat at 4°C (1.36×10⁻³ cm²s⁻¹). K_z calculated from profiles of excess radon-222 generally agree with those from the temperature data. Compared to the open lake, the corral has a more shallow epilimnion. However, during calm meteorological conditions, vertical mixing in the upper 10 m is similar outside and inside the corral. Supported by the Swiss National Science Foundation within the framework for its National Research Program on ‘Lake Currents.’     

Surface energy balance at a tropical station

Summary Studies of various fluxes, namely net radiation, soil heat, sensible heat and latent heat observed at a tropical station are presented in this paper. The time variation of these fluxes are examined in relation to various meteorological parameters and atmospheric conditions. The turbulent transfer coefficients have been evaluated to examine the applicability of the classical theory or the non-equivalence theory for eddy transport in the lower layers of the atmosphere. The energy balance at a tropical station is evaluated. It is found over year there is a net surplus of 94,000 ly. A detailed discussion of the disposal of this energy by various consuming processes is given.Symbols and notation All the quantities represented by symbols in the text of the paper are defined below C _p specific heat at constant pressure in cal. g^–1 °K - E evaporation in g cm^–2 hr^–1 - E ^* evaporative heat flux cal. cm^–2 sec^–1 (in Eq. 10) - e vapour pressure in millibars - e _z ,e _2z vapour pressure at heightsz and 2z - g acceleration due to gravity - H sensible heat flux cal cm^–2 sec^–1 (in Eq. 12) - K _M ,K _H ,K _W coefficients of eddy diffusivities of momentum, heat, and water vapour respectively in cm² sec^–1 - k von Karman' constant=0.4 - L Monin-Obukhov length (according to Monin and Obukhov [53] the structure of the turbulent boundary layer is determined by the non-dimensional variableZ/L whereL is defined byL=–(u _* ³ C _p T)/(kgH) - ly langleys - Q _c Q—sensible heat flux in langleys (in Eqs. 3 and 4) - Q _e E—latent heat flux in langleys (in Eqs. 3 and 4) - Q _s S—soil heat flux in langleys (in Eqs. 3 and 4) - Q _i Q _c +Q _e +Q _s whenK _M K _H K _W , (in Eq. 6) - Q' _i Q' _c +Q' _e +Q _s whenK _M =K _H =K _W (in Eq. 7) - qq mean specific humidity g kg^–1     

Aerosol deposition velocities on the Pacific and Atlantic oceans calculated from7Be measurements

The concentrations of⁷Be have been measured in Pacific and Atlantic ocean water for the past several years to determine the deposition velocity of aerosol particles on the ocean surface.⁷Be is produced at a relatively constant rate in the atmosphere by spallation reactions of cosmic rays with atmospheric nitrogen and oxygen. Immediately after its formation⁷Be becomes attached to aerosol particles, and therefore can serve as tracers of the subsequent behavior of these particles. Isopleths of⁷Be surface water concentrations,⁷Be inventory in the ocean, and deposition velocity have been prepared for the Pacific Ocean from 30°S to 60°N and for the Atlantic Ocean from 10°N to 55°N. The concentrations, inventories and deposition velocities tended to be higher in regions where precipitation was high, and generally increased with latitude. The average flux of⁷Be across the ocean surface was calculated to be 0.027 atoms cm^?2 s^?1 which is probably not significantly greater than the worldwide average⁷Be flux across land and ocean surfaces of 0.022 atoms cm^?2 s^?1 calculated by Lal and Peters. The average deposition velocity was calculated to be 0.80 cm s^?1. This value may be 10–50% too low, since it was calculated using atmospheric⁷Be concentrations which were measured at continental stations. Measurements of atmospheric⁷Be concentrations at ocean stations suggest that the concentrations at the continental stations averaged 10–50% higher than the concentrations over the ocean.     

Constrains on gravity wave induced diffusion in the middle atmosphere

A review of the important constraints on gravity wave induced diffusion of chemical tracers, heat, and momentum is given. Ground-based microwave spectroscopy measurements of H₂O and CO and rocket-based mass spectrometer measurements of Ar constrain the eddy diffusion coefficient for constituent transport (K _zz ) to be (1–3)×10⁵ cm²s^–1 in the upper mesosphere. Atomic oxygen data also limitsK _zz to a comparable value at the mesopause. From the energy balance of the upper mesosphere the eddy diffusion coefficient for heat transport (D _H ) is, at most 6×10⁵ cm²s^–1 at the mesopause and decreasing substantially with decreasing altitude. The available evidence for mean wind deceleration and the corresponding eddy diffusion coefficient for momentum stresses (D _M ) suggests that it is at least 1×10⁶ cm²s^–1, in the upper mesosphere. Consequently the eddy Prandtl number for macroscopic scale lengths is >3.     

On the periodic variations of geomagnetic activity indices Ap and ap

Yearly averages of geomagnetic activity indices Ap for the years 1967–1984 are compared to the respective averages of v² · B_s, where v is the solar wind velocity and B_s is the southward interplanetary magnetic field (IMF) component. The correlation of both quantities is known to be rather good. Comparing the averages of Ap with v² and B_s separately we find that, during the declining phase of the solar cycle, v² and during the ascending phase B_s have more influence on Ap. According to this observation (using Fourier spectral analysis) the semiannual and 27 days, Ap variations for the years 1932–1993 were analysed separately for years before and after sunspot minima. Only those time-intervals before sunspot minima with a significant 27-day recurrent period of the IMF sector structure and those intervals after sunspot minima with a significant 28–28.5-day recurrent period of the sector structure were used. The averaged spectra of the two Ap data sets clearly show a period of 27 days before and a period of 28–29 days after sunspot minimum. Moreover, the phase of the average semiannual wave of Ap is significantly different for the two groups of data: the Ap variation maximizes near the equinoxes during the declining phase of the sunspot cycle and near the beginning of April and October during the ascending phase of the sunspot cycle, as predicted by the Russell-McPherron (R-M) mechanism. Analysing the daily variation of ap in an analogue manner, the same equinoctial and R-M mechanisms are seen, suggesting that during phases of the solar cycle, when ap depends more on the IMF-B_s component, the R-M mechanism is predominant, whereas during phases when ap increases as v increases the equinoctial mechanism is more likely to be effective.     

On conditions for the unique inversion of seismic travel-time curves

It is shown that when the travel-time curve of a refracted wave from a surface source is known and at least one of the following conditions is satisfied, i.e. when

1. the travel-time curve of a wave reflected from a horizontal interface lying below the deepest low velocity layer is known, or
2. the travel-time curve of a wave from a deep source situated below the deepest low velocity layer is known, or
3. the measureH(u)=mes {z∶z≥0,v ^?1 (z)≥u} is analytical in some segment [c, d], where \(0< c< d< \infty , c< a_n , H(a_n ) = \bar z_n ,\bar z_n\) is the depth of the lower end of the deepest low velocity layer and in the interval [c, ∞) an analytical functionH(u)) exists which providesH(u)≡H(u)) ifu∈[c, d], then (1) velocityv(z) outside the low velocity layers and (2) the measureH _k (u)=mes {z∶z∈L _k,v ^?1 (z)≥u} for each low velocity layerL _k,k=1, 2, ..., n, are defined unambiguously.

     

Persistent weak thermal stratification inhibits mixing in the epilimnion of north-temperate Lake Opeongo,Canada

Persistent weak temperature stratification characterizes the epilimnion of Lake Opeongo, Ontario, Canada, and reduces the magnitude of turbulent mixing. Throughout July and August 2009, the epilimnion was isothermal for only 34 % of the record, while for 28 % of the record there was at least a 2 °C temperature difference across the 5 m deep epilimnion. During these stratified periods, there were increases in gradient Richardson numbers (Ri _g ), and decreases in rates of dissipation of turbulent kinetic energy ( $\varepsilon$ ), the turbulence activity parameter (I = ε/νN ²), an indicator of active mixing, and vertical eddy diffusivity (K _z ) inferred from temperature microstructure profiles. During periods of shear induced mixing, values of ε approached 10^?6 m² s^?3 and decreased during periods of increasing Ri _g . For 0 < Ri _g  < 1, average values of I were ~1,000 and values of K _z were slightly higher than 10^?4 m² s^?1. For Ri _g >1, average values of I were ~300 and K _z was reduced by one to three orders of magnitude. Mixing during cold fronts occurred over time scales of minutes to hours, which worked to erode diurnal thermoclines. However, during periods of persistent secondary thermoclines, mixing was suppressed throughout the epilimnion.     

Vertical mixing in Überlinger See,western part of Lake Constance

Depth variable vertical eddy diffusion coefficients for heat (K _z) were calculated from continuously measured temperature profiles in Überlinger See (western part of Lake Constance). The temperatures were averaged over vertical intervals of 10 m yielding 14 discrete values (maximum depth of Überlinger See: 147 m). A linear fit from 10 June to 29 September 1987 was used to smooth the significant temperature fluctuations caused by internal seiches of Lake Constance.Assuming horizontal homogeneity for the smoothed data the Gradient-Flux-Method was applied to compute vertical diffusion coefficientsK _z at different depths using the depth variable volumes and surfaces of the 14 layers. The resulting mean diffusion coefficients for the period from June to September are 0.04 cm²/s near the thermocline and up to 0.8 cm²/s in deeper strata (accuracy: ± 50%). It is shown that horizontal mixing between Überlinger See and Obersee (main lake) alters the computation ofK _z by less than 50%.A relationship betweenK _z and stability (Brunt-Väisälä) frequencyN is found which corresponds well to the theory of internal wave induced turbulence.Combining the diffusion coefficients with measured phosphorus profiles, a phosphorus flux from the hypolimnion to the epilimnion of (0.7 ± 0.4) mg P m^–2 d^–1 was calculated, corresponding to about 20% of the average external loading per area of Lake Constance in 1986.     

On the Correction of Spatial and Statistical Uncertainties in Systematic Measurements of 222Rn for Earthquake Prediction

In earthquake prediction studies, the regional behaviour of accurate ²²²Rn measurements at a set of sites plays a significant role. Here, measurements are obtained using active and passive radon detector systems in an earthquake-active region of Turkey. Two new methods are proposed to explain the spatial behaviours and the statistical uncertainties in the ²²²Rn emission measurements along fault lines in relation to earthquake occurrence. The absolute point cumulative semivariogram (APCSV) and perturbation method (PM) help to depict the spatial distribution patterns of ²²²Rn in addition to the joint effects of the K _dr, the radon distribution coefficient, and the perturbation radon distribution coefficient (PRDC). The K _dr coefficient assists in identifying the spatial distributional behaviour in ²²²Rn concentrations and their migration along the Earth’s surface layers. The PRDC considers not only the arithmetic averages but also the variances (or standard deviations) and the correlation coefficients, in addition to the size of the error among the ²²²Rn measurements. The applications of these methodologies are performed for 13,000 ²²²Rn measurements that are deemed to be sufficient for the characterization of tectonics in the Keban Reservoir along the East Anatolian Fault System (EAFS) in Turkey. The results are evaluated for the ?çme earthquake (M _L 5.4, 5.7 km, 23 June 2011), which occurred in the vicinity of the EAFS.     

Transient excess-radon profiles in Pacific bottom water

Five near-bottom excess-radon profiles have been measured at the Geosecs-I station in the northeast Pacific, at varying intervals over a period of two and a half years. These profiles vary considerably in both structure and radon concentration, indicating transient characteristics of the bottom water in the deep Pacific. Only two of the five profiles are of the quasi-exponential type (Y. Chung and H. Craig); the stationary vertical eddy diffusivities calculated from these two profiles are 129 cm²/sec in November, 1971, and 22 cm²/sec obtained five months later.A single bottom-radon profile was measured in the western-boundary-current region of the South Pacific at the Geosecs-III station. This profile is also of the quasi-exponential type, with a vertical diffusivity of 32 cm²/sec. Although the radon concentrations of the three quasi-exponential profiles and the calculated diffusivities are quite different, the integrated excess-radon inventory in the water column, and the calculated flux of radon across the sediment—water interface, vary by only a factor of two in the two areas studied.