scholarly journals Ion production rate in a boreal forest based on ion, particle and radiation measurements

2004 ◽  
Vol 4 (7) ◽  
pp. 1933-1943 ◽  
Author(s):  
L. Laakso ◽  
T. Petäjä ◽  
K. E. J. Lehtinen ◽  
M. Kulmala ◽  
J. Paatero ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Production Rate ◽  
Ion Pairs ◽  
External Radiation ◽  
Hygroscopic Growth ◽  
Production Rates ◽  
Particle Measurements ◽  
Ion Production ◽  
Aerosol Particle Size ◽  
Concentration Measurements

Abstract. In this study the ion production rates in a boreal forest were studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produced reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 ion pairs cm-3s-1, and based on external radiation and radon measurements, 4.5 ion pairs cm-3s-1. The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3nm, so the sink of small ions during the nucleation events was underestimated. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. Another reason for the discrepancy is the nucleation mechanism itself. If the ions are somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days.

scholarly journals Ion production rate in a boreal forest based on ion, particle and radiation measurements

2004 ◽  
Vol 4 (4) ◽  
pp. 3947-3973 ◽  
Author(s):  
L. Laakso ◽  
T. Petäjä ◽  
K. E. J. Lehtinen ◽  
M. Kulmala ◽  
J. Paatero ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Production Rate ◽  
Radiation Energy ◽  
External Radiation ◽  
Hygroscopic Growth ◽  
Production Rates ◽  
Particle Measurements ◽  
Ion Production ◽  
Aerosol Particle Size ◽  
Concentration Measurements

Abstract. In this study the ion production rates in a boreal forest are studied based on two different methods: 1) cluster ion and particle concentration measurements, 2) external radiation and radon concentration measurements. Both methods produce reasonable estimates for ion production rates. The average ion production rate calculated from aerosol particle size distribution and air ion mobility distribution measurements was 2.6 cm−3s−1 and based on external radiation and radon measurements 4.5 cm−3s−1. The first method based on ion and particle measurements gave lower values for the ion production rates especially during the day. A possible reason for this is that particle measurements started only from 3 nm, so the sink of small ions during the nucleation events was underestimated. Another reason is that the possible fogs, which caused an extra sink of small ions are not taken into account in the calculations. It may also be possible that the hygroscopic growth factors of aerosol particles were underestimated. A fourth possible reason for the discrepancy is the nucleation mechanism itself. If the ions were somehow present in the nucleation process, there could have been an additional ion sink during the nucleation days. On the other hand, not all the radiation energy is converted to ions and the possible effect of alpha recoil is also omitted.

VARIATION OF CORTISOL METABOLISM AS A CONTRIBUTING FACTOR TO DISCREPANCIES IN THE MEASUREMENT OF CORTISOL PRODUCTION RATE

1972 ◽  
Vol 70 (1) ◽  
pp. 89-96 ◽  
Author(s):  
M. J. Levell
Keyword(s):  
Production Rate ◽  
Isotope Dilution ◽  
Normal Subjects ◽  
Contributory Factor ◽  
Morning Dose ◽  
Production Rates ◽  
Evening Dose ◽  
Cortisol Metabolism

ABSTRACT Five normal subjects were given [14C] cortisol in the morning and [3H] cortisol in the evening, in both cases by mouth. The excretion of radioactivity in tetrahydrocortisol (THF) and tetrahydrocortisone (THE) was measured by a modified form of reverse isotope dilution. In 2 subjects, the ratio of isotopic THF/isotopic THE was higher after the evening dose than after the morning dose. In 1 subject the ratio decreased. In 2 subjects it did not change. Cortisol production rates calculated from THF were usually higher than those calculated from THE. The observed variations of metabolism were only a contributory factor to these discrepancies.

scholarly journals Hygroscopic properties of ultrafine aerosol particles in the boreal forest: diurnal variation, solubility and the influence of sulfuric acid

2007 ◽  
Vol 7 (1) ◽  
pp. 211-222 ◽  
Author(s):  
M. Ehn ◽  
T. Petäjä ◽  
H. Aufmhoff ◽  
P. Aalto ◽  
K. Hämeri ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Boreal Forest ◽  
Diurnal Variation ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Time Of Day ◽  
New Particle Formation ◽  
Hygroscopic Growth ◽  
Hygroscopic Properties

Abstract. The hygroscopic growth of aerosol particles present in a boreal forest was measured at a relative humidity of 88%. Simultaneously the gas phase concentration of sulfuric acid, a very hygroscopic compound, was monitored. The focus was mainly on days with new particle formation by nucleation. The measured hygroscopic growth factors (GF) correlated positively with the gaseous phase sulfuric acid concentrations. The smaller the particles, the stronger the correlation, with r=0.20 for 50 nm and r=0.50 for 10 nm particles. The increase in GF due to condensing sulfuric acid is expected to be larger for particles with initially smaller masses. During new particle formation, the changes in solubility of the new particles were calculated during their growth to Aitken mode sizes. As the modal diameter increased, the solubility of the particles decreased. This indicated that the initial particle growth was due to more hygroscopic compounds, whereas the later growth during the evening and night was mainly caused by less hygroscopic or even hydrophobic compounds. For all the measured sizes, a diurnal variation in GF was observed both during days with and without particle formation. The GF was lowest at around midnight, with a mean value of 1.12–1.24 depending on particle size and if new particle formation occurred during the day, and increased to 1.25–1.34 around noon. This can be tentatively explained by day- and nighttime gas-phase chemistry; different vapors will be present depending on the time of day, and through condensation these compounds will alter the hygroscopic properties of the particles in different ways.

scholarly journals Quantifying the controls on potential soil production rates: a case study of the San Gabriel Mountains, California

2017 ◽  
Vol 5 (3) ◽  
pp. 479-492 ◽  
Author(s):  
Jon D. Pelletier
Keyword(s):  
Production Rate ◽  
Small Subset ◽  
Published Data ◽  
Production Rates ◽  
Soil Thickness ◽  
Cold Temperatures ◽  
San Gabriel Mountains ◽  
Erosion Rates ◽  
Soil Production ◽  
Average Slope

Abstract. The potential soil production rate, i.e., the upper limit at which bedrock can be converted into transportable material, limits how fast erosion can occur in mountain ranges in the absence of widespread landsliding in bedrock or intact regolith. Traditionally, the potential soil production rate has been considered to be solely dependent on climate and rock characteristics. Data from the San Gabriel Mountains of California, however, suggest that topographic steepness may also influence potential soil production rates. In this paper I test the hypothesis that topographically induced stress opening of preexisting fractures in the bedrock or intact regolith beneath hillslopes of the San Gabriel Mountains increases potential soil production rates in steep portions of the range. A mathematical model for this process predicts a relationship between potential soil production rates and average slope consistent with published data. Once the effects of average slope are accounted for, a small subset of the data suggests that cold temperatures may limit soil production rates at the highest elevations of the range due to the influence of temperature on vegetation growth. These results suggest that climate and rock characteristics may be the sole controls on potential soil production rates as traditionally assumed but that the porosity of bedrock or intact regolith may evolve with topographic steepness in a way that enhances the persistence of soil cover in compressive-stress environments. I develop an empirical equation that relates potential soil production rates in the San Gabriel Mountains to the average slope and a climatic index that accounts for temperature limitations on soil production rates at high elevations. Assuming a balance between soil production and erosion rates on the hillslope scale, I illustrate the interrelationships among potential soil production rates, soil thickness, erosion rates, and topographic steepness that result from the feedbacks among geomorphic, geophysical, and pedogenic processes in the San Gabriel Mountains.

scholarly journals Characterization of air ions in boreal forest air during BIOFOR III campaign

2005 ◽  
Vol 5 (3) ◽  
pp. 2749-2790 ◽  
Author(s):  
U. Hõrrak ◽  
P. P. Aalto ◽  
J. Salm ◽  
J. M. Mäkelä ◽  
L. Laakso ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Correlation Coefficient ◽  
Aerosol Particles ◽  
Ion Pairs ◽  
Ion Concentration ◽  
Cluster Ions ◽  
Statistical Characteristics ◽  
Nucleation Event ◽  
Air Ions ◽  
20 Nm

Abstract. The behavior of the concentration of positive small (or cluster) air ions and naturally charged nanometer aerosol particles (aerosol ions) has been studied on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. Statistical characteristics of the concentrations of cluster ions, two classes of aerosol ions of the sizes of 2.5–8 nm and 8–ca 20 nm and the quantities that determine the balance of small ions in the atmosphere have been given for the nucleation event days and non-event days. The dependence of small ion concentration on the ion loss (sink) due to aerosol particles was investigated applying a model of bipolar diffusion charging of particles by small ions. The small ion concentration and the ion sink were closely correlated (correlation coefficient 87%) when the fog events and the hours of high relative humidity (above 97%), as well as nocturnal calms and weak wind (wind speed<0.6 m s-1 had been excluded. In the case of nucleation burst events, variations in the concentration of small positive ions were in accordance with the changes caused by the ion sink due to aerosols; no clear indication of positive ion depletion by ion-induced nucleation was found. The estimated average ionization rate of air at the Hyytiälä station in early spring, when the ground was partly covered with snow, was about 4.8 ion pairs cm-3 s-1. The study of the charging state of nanometer aerosol particles (2.5–8 nm) revealed a strong correlation (correlation coefficient 88%) between the concentrations of particles and their charged fraction (positive air ions) during nucleation bursts. The estimated charged fraction of particles, which varied from 3% to 6% considering various nucleation event days, confirms that these particles are almost quasi-steady state charged. Also the particles and air ions in the size range of 8–ca 20 nm showed a good qualitative consistency; the correlation coefficient was 92%.

scholarly journals Characterization of positive air ions in boreal forest air at the Hyytiälä SMEAR station

2007 ◽  
Vol 7 (4) ◽  
pp. 9465-9517 ◽  
Author(s):  
U. Hõrrak ◽  
P. P. Aalto ◽  
J. Salm ◽  
K. Komsaare ◽  
H. Tammet ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Correlation Coefficient ◽  
Aerosol Particles ◽  
Ion Pairs ◽  
Coniferous Forest ◽  
Ion Concentration ◽  
Statistical Characteristics ◽  
Nucleation Event ◽  
Air Ions ◽  
20 Nm

Abstract. The behavior of the concentration of positive small (or cluster) air ions and naturally charged nanometer aerosol particles (aerosol ions) has been studied on the basis of measurements carried out in a boreal forest at the Hyytiälä SMEAR station, Finland, during the BIOFOR III campaign in spring 1999. Statistical characteristics of the concentrations of cluster ions, two classes of aerosol ions of the sizes of 2.5–8 nm and 8–ca. 20 nm and the quantities that determine the balance of small ions in the atmosphere have been given for the nucleation event days and non-event days. The dependence of small ion concentration on the ion loss (sink) due to aerosol particles was investigated applying a model of bipolar diffusion charging of particles by small ions. The small ion concentration and the ion sink were closely correlated (correlation coefficient –87%) when the fog events and the hours of high relative humidity (above 95%), as well as nocturnal calms and weak wind (wind speed <0.6 m s−1) had been excluded. However, an extra ion loss term presumably due to small ion deposition on coniferous forest with a magnitude equal to the average ion loss to pre-existing particles is needed to explain the observations. Also the hygroscopic growth correction of measured aerosol particle size distributions was found to be necessary for proper estimation of the ion sink. In the case of nucleation burst events, variations in the concentration of small positive ions were in accordance with the changes caused by the ion sink due to aerosols; no clear indication of positive ion depletion by ion-induced nucleation was found. The estimated average ionization rate of the air at the Hyytiälä station in early spring, when the ground was partly covered with snow, was about 6 ion pairs cm−3 s−1. The study of the charging state of nanometer aerosol particles (2.5–8 nm) revealed a strong correlation (correlation coefficient 88%) between the concentrations of particles and positively charged particles (positive air ions) during nucleation bursts. The estimated charged fraction of particles, which varied from 3% to 6% considering various nucleation event days, confirms that these particles are almost quasi-steady state charged. Also the particles and air ions in the size range of 8–ca. 20 nm showed a good qualitative consistency; the correlation coefficient was 92%.

scholarly journals Aleutian island arc magma production rates and mechanisms

2019 ◽  
Author(s):  
Yongliang Bai ◽  
Diya Zhang ◽  
Dongdong Dong ◽  
Shiguo Wu ◽  
Zhenjie Wang
Keyword(s):  
High Temperature ◽  
Production Rate ◽  
Island Arc ◽  
Mantle Melting ◽  
Fracture Zones ◽  
Seismic Profiles ◽  
Production Rates ◽  
Aleutian Arc ◽  
Slab Dehydration ◽  
Arc Magma

Abstract. The variation in island arc magma production rates and their influencing mechanisms are of great significance since island arc magma is considered a main source of continental crust growth. The island arc magma directly originates from the molten mantle wedge, and the mantle melting is driven by fluids or melts from the subducted slab. Slab dehydration flux mainly depends on the slab thermal structures, and subducted slab melting requires a sufficiently high temperature. For the Aleutian subduction system, the subducted Pacific Plate has diverse thermal structures due to the existing fracture zones, ridges and slab window, so it is an ideal region for arc magma production rate research. However, the previous estimations are based on seismic profiles that only provide magma production rates at specific regions of the Aleutian arc, and these results are controversial. Here, we design a magma production rate estimation method based on gravity inversion constrained by deep seismic profiles. The first overview map of magma production rates along the Aleutian arc strike demonstrates that the magma production rates have the same trend as the slab dips, and the peaks correspond to the subduction of the fracture zones and ridges. The potential mechanisms for these correlations are as follows: (1) Slab water flux at subarc depths increases with increasing slab dip. More fluid flux would induce more mantle melting, and so the arc magma production rates are increased. (2) Water-rich serpentine is formed by hydrothermal alteration on or near the surface of the subducted slab when there are fracture zones. Serpentine decomposition at a depth of 80–120 km releases fluids in addition to the fluids released during normal slab dehydration. Therefore, more fluids induce more mantle melting and correspond a larger magma production rate. (3) The slab located in the Emperor Seamounts has a relatively high temperature and is also weak, so its melting is easier. Similarly, more slab melt means more mantle melt and a higher island arc magma production rate.

Volatile fatty acids and sulfide in pressure mains

1995 ◽  
Vol 31 (7) ◽  
pp. 169-179 ◽  
Author(s):  
T. Hvitved-Jacobsen ◽  
K. Raunkjær ◽  
P. H. Nielsen
Keyword(s):  
Fatty Acids ◽  
Organic Matter ◽  
Production Rate ◽  
Volatile Fatty Acids ◽  
Production Rates ◽  
Net Production ◽  
Toc Removal ◽  
Sulfide Production ◽  
Transformation Of Organic Matter ◽  
High Sulfide

The main objective was to study the anaerobic transformation of organic matter and sulfide production during wastewater transportation. Emphasis was on the transformation of easily biodegradable organic matter in terms of volatile fatty acids (VFA). Samples from two intercepting pressure mains located in the Northern part of Jutland, Denmark, were taken. The concentration of VFA in the wastewater varied considerably during day and night, being typically between 5 and 50 g/m3. A net production as well as a net removal of VFA was seen during transportation in the pressure mains probably depending on the quality and quantity of the organic matter. Typically 85% of the VFA was acetate and 10% propionate; the remainder was formate, n-butyrate and iso-butyrate. Observed sulfide production rates from the sewer biofilms were typically 0.05 and 0.005 g S/m2 h at 12 and 4 °C, respectively. A high sulfide production rate corresponded with a high VFA concentration. TOC removal was observed in the pressure mains.

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