A numerical determination of the effect of electric fields and charges on the efficiency with which cloud drops and small raindrops collide with aerosol particles

Summary Numerical calculations were carried out to determine the effect of a vertical electric field on the efficiency with which electrically charged or uncharged cloud drops and small raindrops of diameters ranging from 84 m to 1.248 mm collide with electrically charged or uncharged particles of density 2 gm/cm³ and diameters between 1 and 20 m. For this purpose, numerical flow fields about spheres of Reynolds numbers ranging from 1 to 400 were used to integrate the trajectory of the particle relative to the drop, and the force between two conducting spheres was used to represent the electrostatic force on the particle. The effect of thunderstorm strength electric charges and field on the collision efficiency was found to be highly significant for the smaller collector drops, and declined to insignificance for the largest collector drop.     

Coupled groundwater flow and heat transport simulation for estimating transient aquifer–stream exchange at the lowland River Spree (Germany)

Subsurface flow and heat transport near Freienbrink, NE Germany, was simulated in order to study groundwater–surface water exchange between a floodplains aquifer and a section of the lowland River Spree and an adjacent oxbow. Groundwater exfiltration was the dominant process, and only fast surface water level rises resulted in temporary infiltration into the aquifer. The main groundwater flow paths are identified based on a 3D groundwater flow model. To estimate mass fluxes across the aquifer–surface water interfaces, a 2D flow and heat transport modelling approach along a transect of 12 piezometers was performed. Results of steady‐state and transient water level simulations show an overall high accuracy with a Spearman coefficient ρ = 0.9996 and root mean square error (RMSE) = 0.008 m. Based on small groundwater flow velocities of about 10^?7 to 10^?6 ms^?1, mean groundwater exfiltration rates of 233 l m^?2 d^?1 are calculated. Short periods of surface water infiltration into the aquifer do not exceed 10 days, and the infiltration rates are in the same range. The heat transport was modelled with slightly less accuracy (ρ = 0.8359 and RMSE = 0.34 °C). In contrast to the predominant groundwater exfiltration, surface water temperatures determine the calculated temperatures in the upper aquifer below both surface water bodies down to 10 m during the whole simulation period. These findings emphasize prevailing of heat conduction over advection in the upper aquifer zones, which seems to be typical for lowland streams with sandy aquifer materials and low hydraulic gradients. Moreover, this study shows the potential of coupled numerical flow and heat transport modelling to understand groundwater–surface water exchange processes in detail. Copyright © 2013 John Wiley & Sons, Ltd.     

Estimation of heat discharge rates using infrared measurements by a helicopter-borne thermocamera over the geothermal areas of Unzen volcano, Japan

Unzen volcano is situated on Shimabara Peninsula, western Kyushu, Japan. On the flank of the volcano, the Obama, Unzen and Shimabara hot springs are aligned in a direction from the southwest to the northeast across the peak. At Obama and Shimabara, heat is transferred mainly by water flow. But at Unzen heat is transferred by the discharge of natural steam and by conduction as well as water flow. In order to estimate the heat discharge by mechanisms other than water flow, infrared measurements by a helicopter-borne thermocamera were conducted over the Unzen hot spring area. The heat discharge was calculated from the thermal image by a method based on heat balance of the ground surface resulting in a value of 1.9 × 10⁶ cal/s (7.9 MW). The heat discharged by all mechanisms including that by water flow is estimated to be 5.0 × 10⁶ cal/s (21 MW). Similar preliminary estimates have been made for heat discharge at the Obama and Shimabara hot springs giving values of about 1.2 × 10⁷ cal/s (50 MW) and 1.0 × 10⁵ cal/s (0.4 MW), respectively. These values indicate that the heat discharge decreases with distance from the southwest to the northeast direction across the volcano. The total heat discharge from three hot spring areas on Unzen volcano is about 1.7 × 10⁷ cal/s (71 MW).The heat balance method appears useful for quantitative analysis of regional trends but its accuracy may not be always sufficient for detailed surveys. Several methods of determining heat flow, including the heat balance method, were compared at a test field in the Unzen hot spring area. The values obtained by the heat balance method coincide roughly with the other results but more detailed analysis is necessary to improve the accuracy of current methods of geothermal measurements.     

Electrochemical disinfection for ballast water management: Technology development and risk assessment

Ballast water is essential in maintaining the balance and structural integrity of ships during voyage. However, it has created biological invasion threats to the ocean environment. An innovative electrochemical technology was developed in this study. The microorganisms regulated by the International Maritime Organization (D2) were used as the target organisms. It was found that the required energy to meet the D2 was below 0.006 kWh/m³. The size of disinfector (m³) was about 0.5% of treatment flow rate (m³/h). The complete disappearance of chlorine in seawater was achieved after three days. The ballast tank corrosion was not worsened due to the application of technology. The ecotoxicity studies showed no toxic effect on fish, invertebrate, and algae. Finally, the environmental risk assessment showed the treated water did not pose threats to the environment. It can therefore be concluded that the technology provides a cost-effective and environmental friendly solution to ballast water management.     

Convection of geothermal fluids in the timanfaya volcanic area (Lanzarote,Canary Islands)

Summary A mathematical model has been derived to study the superficial thermal anomalies to be found in Lanzarote (605°C at 13 m depth) in association with the convection of geothermal fluids. The model is valid for a wide range of conditions, in particular for those found beneath the Timanfaya volcano (active between 1730 and 1736). Geological and geophysical data suggest that the heat source is related to a cylindrical magma body with a radius of 200±100 m and a top temperature of 850±100°C at a depth of 4±1 km.Energy is transported through fractures by magmatic volatiles and/or by water vapour coming from a deeply located water table: in such a convection system, a fluid flow of 10 l/m² day, which corresponds to a thermal flux of 130 W/m², is sufficient to explain the temperature anomalies observed at the surface. The relationships between gas flow and the surface temperatures, as well as the thermal gradients in the conducting fracture are also discussed.     

Thermal Structure of the Ionian Slab

We propose a thermal model of the subducting Ionian microplate. The slab sinks in an isothermal mantle, and for the boundary conditions we take into account the relation between the maximum depth of seismicity and the thermal parameter L_th of the slab, which is a product of the age of the subducted lithosphere and the vertical component of the convergence rate. The surface heat-flux dataset of the Ionian Sea is reviewed, and a convective geotherm is calculated in its undeformed part for a surface heat flux of 42 mW m^–2, an adiabatic gradient of 0.6 mK m^–1, a mantle kinematic viscosity of 10¹⁷ m² s^–1 and an asthenosphere potential temperature of 1300°C. The calculated temperature-depth distribution compared to the mantle melting temperature indicates the decoupling limit between lithosphere and asthenosphere occurs at a depth of 105 km and a temperature of 1260°C. A 70–km thick mechanical boundary layer is found. By considering that the maximum depth of the seismic events within the slab is 600 km, a L_th of 4725 km is inferred. For a subduction rate equal to the spreading rate, the corresponding assimilation and cooling times of the microplate are about 7 and 90 Myr, respectively. The thermal model assumes that the mantle flow above the slab is parallel and equal to the subducting plate velocity of 6 cm yr^–1, and ignores the heat conduction down the slab dip. The critical temperature, above which the subduced lithosphere cannot sustain the stress necessary to produce seismicity, is determined from the thermal conditions governing the rheology of the plate. The minimum potential temperature at the depth of the deepest earthquake in the slab is 730°C.     

Effects of drilling cuttings on the behaviour of the Norway lobster Nephrops norvegicus

Small quantities of drilling cuttings (100 g/250 cm²) were found to affect both the survival and general behaviour of Nephrops norvegicus held in experimental aquaria. In one experiment volatile hydrocarbons released from the cuttings caused a significant decrease (p < 0.05) in the beat of the exopodite on the third maxilliped. Flicking rates of the antennule and the time taken to identify and capture food introduced into the tanks were unaffected by exposure to cuttings. When the water flow through the tanks was interrupted for 12 h, 58% of animals died after exposure to the highest concentration of cuttings but those at the lower concentrations survived. After the water flow was restored the remaining survivors showed disorientated behaviour and uncoordinated movements which lasted for about 36 h. In this condition animals will be more vulnerable to predators. This unnatural behaviour may have serious implications for natural populations exposed to cuttings discharge in the close vicinity of offshore drilling platforms.     

Heat loss from the earth: A constraint on Archaean tectonics from the relation between geothermal gradients and the rate of plate production

The models suggested for the oceanic lithosphere which best predict oceanic heat flow and depth profiles are the constant thickness model and a model in which the lithosphere thickens away from the ridge with a heat source at its base. The latter is considered to be more physically realistic. Such a model, constrained by the observed oceanic heat flow and depth profiles and a temperature at the ridge crest of between 1100°C and 1300°C, requires a heat source at the base of the lithosphere of between 0.5 and 0.9 h.f.u., thermal conductivities for the mantle between 0.005 and 0.0095 cal cm⁻¹ °C⁻¹ s⁻¹ and a coefficient of thermal expansion at 840°C between 4.1 × 10⁻⁵ and 5.1 × 10⁻⁵ °C⁻¹. Plate creation and subduction are calculated to dissipate about 45% of the total earth heat loss for this model. The efficiency of this mechanism of heat loss is shown to be strongly dependent on the magnitude of the basal heat source. A relation is derived for total earth heat loss as a function of the rate of plate creation and the amount of heat transported to the base of plates. The estimated heat transport to the base of the oceanic lithosphere is similar to estimates of mantle heat flow into the base of the continental lithosphere. If this relation existed in the past and if metamorphic conditions in late Archaean high-grade terrains can be used to provide a maximum constraint on equilibrium Archaean continental thermal gradients, heat flow into the base of the lithosphere in the late Archaean must have been less than about 1.2–1.5 h.f.u. The relation between earth heat loss, the rate of plate creation and the rate of heat transport to the base of the lithosphere suggests that a significant proportion of the heat loss in the Archaean must have taken place by the processes of plate creation and subduction. The Archaean plate processes may have involved much more rapid production of plates only slightly thinner than at present.     

Heat flow in the natural gas field of Hajduszoboszló

Summary The natural gas field of Hajduszoboszló in the Hungarian plain offered several virgin rock temperature measurements, further rock samples for measurement of conductivity. The Paleozoic bottom rock is covered by Mezozoic and Tertiary sediments inclusively flysch. One big and three small gas caps are found at a depth of about 1000 to 1200 in anticlyne structures. The average temperature gradient is 60° C/km. The heat flow is between 2.2 and 2.7 cal/cm² sec, which is consistent to other heat flow values measured in the Hungarian basin.     

On the thermal evolution of the earth

The two principal contributions to the surface heat flow of the earth are the cooling of the earth and the heat production of radioactive isotopes. As the rate of heat production decreases with time the temperature of the interior of the earth also decreases. The rate of decrease is determined by the ability of solid-state mantle convection to transport the heat to the surface. The dominant effect is the exponential temperature dependence of the mantle viscosity. The non-dimensional mantle temperature can be parameterised in terms of the Rayleigh number for mantle convection. It is found that the mantle is currently cooling at a rate of 36°K/10⁹ years and that three billion years ago the mean temperature was 150°K higher than it is today; 83% of the present surface heat flow is attributed to the decay of radioactive isotopes and 17% to the cooling of the earth. The corresponding mean concentration of uranium in the mantle is 32 ppb.     

Terrestrial heat flow in Japan

Terrestrial heat flow, Q=K×ΔT/ΔZ cal/cm² sec has been determined at 51 localities (39 on land and 12 in the sea) in and around the Japanese Islands. The average values of observed heat flow in land and sea are 1.53µ cal/cm²sec and 1.48µcal/cm²sec respectively. These value do not differ greatly from the world’s averages. The outstanding features of the heat flow distribution are as follows:a) High heat flow region (Q>2.0µcal/cm²sec) exists in the Inner Zone of the Honshu Arc. This region of high heat flow is more distinct in the northeastern Japan than in the southwestern Japan.b) The High heat flow region seems to extend, through the Fossa Magna area, down to the Izu-Mariana Arc.c) It is also probable that a similar high heat flow zone exists in the inner side of the Kurile Arc.d) These zones of high heat flow precisely coincide with the zones of the Cenozoic orogeny in the area concerned.e) Far off the coast of the northeastern Japan, the area at about 150° E may be a high heat flow region.f) Low heat flow (Q<1.0µcal/cm²sec) prevails in the Pacific coast side of the northeastern Japan and in the oceanic area directly east of it, including the area of the Japan Trench.g) The region bounded by the above mentioned high and low heat flow regions has heat flow which is more or less normal. Based on these measurements, a « steady state ” temperature distribution in the crust has been calculated for each of the above regions of high, low and intermediate heat flow, and it was found that there is a large temperature differences between the bottom of the crust of the high and low heat flow regions: the temperature at the Moho boundary in the high heat flow regions should be as high as some 800～1000°C (d=27 km), whereas that under the low heat flow region should be only about 200°C (d=23 km). The high general temperature at the Moho under the high heat flow region seems to favor a production of magma in the upper mantle. Calculated Moho temperatures disfavor the hypothesis that the Moho boundary is due to phase transition.     

BOTTOM MELTING IN THE CENTRAL ZONE OF THE ICE SHIELD ON THE ANTARCTIC CONTINENT AND ITS INFLUENCE UPON THE PRESENT BALANCE OF THE ICE MASS

ABSTRACT

An analysis of the present balance of the ice mass on the Antarctic continent carried out by several authors, shows a substantial excess of supply over expenditure. However, no consideration was given to the possibility of a decrease in the amount of Antarctic ice by melting at its lower surface and a run-off of water. This paper is intended to fill this gap.

A theoretical analysis shews that the possibility of such melting exists for a definite relationship between the ice thickness, the temperature at its surface, the rate of accumulation and the geothermal heat flow.

Using numerical values for these factors, it is shown that throughout the entire central zone of the Antarctic ice cap, over an area of about 12 × 10⁶ sq.km, there is continuous melting at the bed.

Contours of the rates of bottom melting are given on a map of the continent. The maximun rate of melting is about 6–7 mm of water per year; the average rate in the area of melting is about 3 mm of water per year, equivalent to a volume not exceeding 20 km³ of water per year, and not more than several percent of the total ice balance of the continent.     

Chemical and isotopic methods for management of artificial recharge in Mazraha Station (Damascus Basin,Syria)

Artificially enhancing recharge rate into groundwater aquifer at specially designed facilities is an attractive option for increasing the storage capacity of potable water in arid and semi‐arid region such as Damascus basin (Syria). Two dug wells (I and II) for water injection and 24 wells for water extraction are available in Mazraha station for artificial recharge experiment. Chemical and stable isotopes (δ²H and δ¹⁸O) were used to evaluate artificial recharge efficiency. 400 to 500*10³ m³ of spring water were injected annually into the ambient shallow groundwater in Mazraha station, which is used later for drinking purpose. Ambient groundwater and injected spring water are calcium bicarbonate type with EC about 880 ± 60 μS/cm and 300 ± 50 μS/cm, respectively. The injected water is under saturated versus calcite and the ambient groundwater is over saturated, while the recovered water is near equilibrium. It was observed that the injection process formed a chemical dilution plume that improves the groundwater quality. Results demonstrate that the hydraulic conductivity of the aquifer is estimated around 6.8*10^?4 m/s. The effective diameter of artificial recharge is limited to about 250 m from the injection wells. Mixing rate of 30% is required in order to reduce nitrate concentration below 50 mg/l which is considered the maximum concentration limit for potable water. Deuterium and oxygen‐18 relationship demonstrates that mixing line between injected water and ambient groundwater has a slope of 6.1. Oxygen‐18 and Cl^? plot indicates that groundwater salinity origin is from mixing process, and no dissolution and evaporation were observed. These results demonstrate the efficiency of the artificial recharge experiments to restore groundwater storage capacity and to improve the water quality. Copyright © 2011 John Wiley & Sons, Ltd.     

A New Thermophoretic Precipitator for Off‐Line Particle Analysis

A new thermophoretic particle precipitator has been developed for representative and efficient collection of aerosol particles from the ambient air and technological pipelines. The device consists of hot and cold plates (5 × 5 cm²) capable of operation at temperature gradients ranging from 20 000 to 100 000 K/m. A gas sample is made to pass through a 1‐mm slot between the plates at a flow rate of up to 1.5 L/min, which makes the device suitable for operation in conjunction with common aerosol instruments including DMA and diffusion batteries with similar operational flow rates. It was shown that the efficiency of the device was highest for the lowest gas flow rate used (0.3 L/min) reaching a level of above 99%. The efficiency was decreased reaching its minimal values at the highest flow rate investigated (1.5 L/min). However, even for highest flow rate, the average efficiency for removal of particle smaller than 60 nm was around 50%.     

Removal of the Alphazurine FG Dye from Simulated Solution by Electrocoagulation

The removal of Alphazurine FG (AF) dye from water by an electrocoagulation process has been studied. The effect of some operational parameters, such as anode material, current density, initial dye concentration, pH of solution, conductivity, and inter‐electrode distance, on the removal efficiency was investigated. Iron and aluminum were used as anodes in the electrocoagulation cell. It was found that the efficiency of the iron anode was better than that of the aluminum anode for AF removal. The factors that affected the removal efficiency were the current density and the initial dye concentration. The removal efficiency increased from about 35% at 25 A m^–2 to about 97% at 100 A m^–2, during 4 min of electrocoagulation. The results exhibited pseudo‐first‐order kinetics for AF removal by electrocoagulation. In addition, a mathematical model was successfully established for predicting the removal efficiency. A comparison between the model results and experimental data gave a high correlation coefficient (R² = 0.9925), which indicates that the model is able to predict the removal efficiency of AF.     

Surface-active substances on rainwater and atmospheric particles

The surface tension lowering by surface-active substances has been measured on rainwater, melted snow, and dispersions of atmospheric particles in water, with a film balance and a tensiometer. The precipitation water was sampled during 1979, 1980, and 1981 in the city of Frankfurt/Main. From measurements with the film balance technique, normalized concentrations of insoluble and weakly soluble surface-active substances have been estimated. Soluble surface-active substances were determined from measurements with a tensiometer. It was found that the normalized concentration of theinsoluble and weakly soluble surface-active material on rainwater or melted snow shows a maximum during late spring of about 2.5 · 10⁻⁷ moles/l and a minimum during wintertime of about 5 · 10⁻⁸ moles/l. These concentrations are too low to influence significantly the condensation of water vapour on cloud droplets or the evaporation of water from them. Thesoluble surface-active material on rainwater or melted snow was found to have concentrations of the order of 2 · 10⁻⁶ moles/l. These concentrations are also too small to have a significant influence on cloud physical processes.     

A detailed study of the distribution of heat flow and radioactivity in New Hampshire (U.S.A.)

We present a set of 39 new determinations of heat flow and radiogenic heat production for several different geological environments in the State of New Hampshire (U.S.A.). With the extensive data set now available for the state, the linear relation of heat flow and heat production appears as a very useful generalization for the study of the heat flow field of a geological province. Our measurements indicate that the vertical distribution of radiogenic heat production is similar in plutonic and metasedimentary rocks. Our data are compatible with the linear relationship established earlier by F. Birch and his co-workers in 1968. Young granites are markedly enriched in radioactive elements and those which do not outcrop are revealed by anomalies in the general relation of heat flow versus radioactivity.Heat flow is high for plutons by low elsewhere. The mean heat flow through metasedimentary formations is 1.15 μcal/cm² s (48 mW/m²), a value near the mean heat flow for old cratons. The lowest heat flow measured is 0.76 μcal/cm² s (32 mW/m²) for a unit poor in radioactivity. The heat flow field grades smoothly into the low heat flow regions of the Canadian Shield.The New Hampshire region is in thermal equilibrium: its heat flow is in secular equilibrium with the heat generated by crustal sources and that supplied from the mantle. In this area, the thermal perturbations due to orogenic events decrease below the detection level in less than 200–275 Ma. The thickness of the layer which is thermally affected during continent-continent collision-type orogenies cannot be greater than about 190 km.     

On the geothermal regime of some tectonic units in Romania

Heat flow values of 33–58 mW m^–2 were found for the Transylvanian Depression, 45–57 mW m^–2 for the crystalline nucleus of the Eastern Carpathians, and 70–120 mW m^–2 for the Neogene volcanic area. Temperature-depth profile and some geophysical implications of the low values for the Transylvanian Depression are discussed, rendering evident clear-cut differences between this tectonic unit and other Noegene depressions. The heat flow values for the other two investigated tectonic units are usual ones for areas of their age.A preliminary map of the heat flow distribution over the Romanian territory is presented and its relation to other geophysical fields is discussed. A positive correlation was found between gravity and heat flow, and a negative one between crustal thickness and heat flow. A general conclusion could be drawn that the heat flow distribution over the Romanian territory seems to be governed by processes taking place in the upper mantle, rather than by the radioactive decay within the crust.     

Heat flow map of the European part of the U.S.S.R.

A heat flow isoline map is presented. Low and relatively constant heat flow has been observed in the old shield areas of the East European Platform (25–40 mW/m²). Increased heat flow (>50 mW/m²) has been found in the Dniepr-Donetz depression. The area south of the East European Platform is characterized by highly variable heat flow (55–100 mW/m²). Some geophysical implications are discussed.     

Terrestrial heat flow in the natural steam field at Larderello

Summary Measurements of thermal gradients and rock conductivity in the steam field of Larderello, along a cross section of about 12 km length, reveal a great anomaly of terrestrial heat flow. Heat flow varies between 6 and 14 cal-cm² sec, while thermal gradients are between 200 and 800 deg C-km. The measurements show that heat flow values characterize better the productive areas than thermal gradient anomalies. Knowing the heat flow it is possible to set up the thermal balance of the steam producing area, which is of considerable importance in planning the production of the steam field.