Characterization and prediction of stormwater runoff quality in sub-tropical rural catchments

Due to scarcity of local data on stormwater pollution levels and rainfall-runoff generation process, very few attempts have been made towards the management of stormwater in sub-tropical rural catchments. An attempt has been made in the present study to characterize and predict the stormwater runoff characteristics using regression modeling from five rural catchments in north-west India. Stormwater samples and flow data were collected from 75 storm events. Samples were analyzed for pH, total suspended solids (TSS), 5-day biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), total kjeldhal nitrogen (TKN), total phosphorous (TP), nitrate-nitrogen (NO ₃ ^- –N), total coliform count (TC), fecal coliform count (FC), Zn, Cu and Fe. It was found that size of the catchment and the land use practices influenced the stormwater quality even in predominantly rural areas, otherwise thought to be homogeneous. The results obtained were related with the antecedent dry days (ADD) and average rainfall. ADD was found to be positively correlated with pollutant loads whereas average rainfall showed negative correlation. The study highlights the importance of ADD in causing greater mean pollutant concentrations except for TKN, TP and NO ₃ ^- –N. Regression models were developed for the studied catchments to estimate mean pollutant concentrations as a function of rainfall variables. Results revealed that measured pollutant concentrations demonstrated high variability with ADD and average rainfall in small rural catchments, whereas in large catchments, factors like land use, extent of imperviousness etc. resulted in low predictability of measured parameters.     

A semiempirical mathematical model of the secondary pollution of water bodies by soluble iron and manganese forms

A semiempirical mathematical model of iron and manganese migration from bottom sediments into the water mass of water bodies has been proposed based on some basic regularities in the geochemistry of those elements. The entry of dissolved forms of iron and manganese under aeration conditions is assumed negligible. When dissolved-oxygen concentration is <0.5 mg/L, the elements start releasing from bottom sediments, their release rate reaching its maximum under anoxic conditions. The fluxes of dissolved iron and manganese (Me) from bottom sediments into the water mass (J _Me) are governed by the gradients of their concentrations in diffusion water sublayer adjacent to sediment surface and having an average thickness of h = 0.025 cm: \({J_{Me}} = - {D_{Me}}\frac{{{C_{Me\left( {ss} \right)}} - {C_{Me\left( w \right)}}}}{h}\) (D _Me ≈ 1 × 10^–9 m²/s is molecular diffusion coefficient of component Me in solution; C _Me(ss) and C _Me(w) ≈ 0 are Me concentrations on sediment surface, i.e., on the bottom boundary of the diffusion water sublayer, and in the water mass, i.e., on the upper boundary of the diffusion water sublayer). The value of depends on water saturation with dissolved oxygen (\({\eta _{{O_2}}}\)) in accordance with the empiric relationship \({C_{Me\left( {ss} \right)}} = \frac{{C_{_{Me\left( {ss} \right)}}^{\max }}}{{1 + k{\eta _{{O_2}}}}}\) (k is a constant factor equal to 300 for iron and 100 for manganese; C _Me(ss) ^max is the maximal concentration of Me on the bottom boundary of the diffusion water sublayer with C _Fe(ss) ^max ≈ 200 μM (11 mg/L), and C _Mn(ss) ^max ≈ 100 μM (5.5 mg/L).     

中国太湖物理—生物工程实验中菱对水质影响的模式

A model on a physico-biological engineering experiment for purifying water in Wulihu Bay of Lake Taihu by using Trapa natans var. bispinosa was constructed. The state variables in water in the physico-biological engineering were ammonium nitrogen (NH₄⁺-N); nitrate nitrogen (NO₃^--N); nitrite nitrogen (NO₂^--N); phosphate phosphorus (PO₄^3--P); dissolved oxygen (DO); nitrogen (N) and phosphorus (P) in detritus; biomass density, N and P in phytoplankton and in Trapa natans var. bispinosa, N and P in the substance adsorbed by the membrane of the engineering and the rootstocks of Trapa natans var. bispinosa. The state variables in bottom mud layer were PO₄^3--P in the core water,exchangeable P and N. The external forcing functions were solar radiation, water temperature, NH₄⁺-N; NO₃^--N; NO₂^--N; PO₄^3--P; N and P in detritus; DO; phytoplankton concentrations in inflow water and the retention time of the water in physico-biological engineering channel. The main physical, chemical and biological processes considered in the model were:growth of Trapa natans var. bispinosa and phytoplankton; oxidation of NH₄⁺-N and NO₂^--N, of detritus break down; N and P sorption by the enclosure cloth of the experimental engineering and by the rootstocks of Trapa natans var. bispinosa in water; reaeration of water; uptake of P, NH₄⁺-N, NO₃^--N by phytoplankton and Trapa natans var. bispinosa:mortality of the phytoplankton and Trapa natans var. bispinosa:settling of detritus; and nutrient release from sediment. Comparison of calculated results and observed results showed that the model was constructed reasonably for the experiment. The mechanism of purifying lake water in the experiment engineering was discussed by the use of the model.     

Examining the fate of WWTP effluent nitrogen using δ 15N–NH4 +, δ 15N–NO 3 − and δ 15N of submersed macrophytes

The use of submersed macrophyte tissue δ ¹⁵N to quantify the level of WWTP effluent use in a highly urbanized and agricultural river was evaluated using several methods. Macrophytes, NH₄ ⁺ and NO₃ ^? were collected by canoe along two 10 km reaches of river, upstream and downstream of two major municipal WWTPs over 3 years. NH₄ ⁺ decreased in concentration while δ ¹⁵N–NH₄ ⁺ increased as a function of distance downstream of both WWTPs, changing in one survey from 13 to 31 ‰ over 1 km. This increase is attributed to the combined effects of volatilization, nitrification and uptake. While NO ₃ ^? concentrations increased downstream of the WWTP over one of the survey reaches, δ ¹⁵N–NO ₃ ^? showed no prominent trend with distance at either. Macrophyte tissue δ ¹⁵N increased with distance downstream of both WWTPs, with a slope not significantly different from that of δ ¹⁵N–NH₄ ⁺ suggesting that macrophytes incorporate effluent NH₄ ⁺ as their main N source in those areas. However, mixing models suggest that towards the end of the reach, where source separation is distinct, macrophytes may utilize background NO ₃ ^? . Our study indicates the difficulty of deriving precise estimates of effluent use by macrophytes in a system where the δ ¹⁵N of the effluent changes rapidly. It also illustrates the utility of macrophytes in describing those changes where the effluent is too attenuated to allow for direct isotopic analysis.     

Hydrochemical Analyses and Evaluation of Groundwater Resources of North Jordan

The hydrochemical analyses of twenty-three springs were used to determine the properties and types of groundwater of the Tertiary-Quaternary Aquifer of northern Jordan. The result shows that the geological formation influences the quality of the investigated groundwater more than the anthropogenic factors. The water of the Quaternary-Tertiary aquifer is enriched in Ca⁺⁺ due to the dissolution of the nearby carbonate rocks. The investigated water has a low EC values with Ca(Na)-HCO₃ water type. Most springs belong to this hydrochemical facies except Malka. Groundwater in the Malka wells has high salinity with NaCl waters and a strong Ca(Mg)-HCO₃ facies (900 to 1000 mg/l TDS). The area long-term hydrochemical data have been also evaluated; general trend of increase of the analyzed ion was observed. Bicarbonate represents the most abundant anion in the studied water, which exceeds the permissible limits. Nitrates (NO ₃ ^? ) also exceed the permissible limit and are the most common contaminant in the investigated water. Data on dissolved major and trace elements (K⁺, Na⁺, Mg²⁺, Ca²⁺, Cl^?, SO ₄ ^2? , Fe, Zn, Cu and Pb) in the investigated water revealed that the concentrations lie within the natural background range. The positive correlation values between various ions indicate that most of ions come from same lithological sources. According to the residual sodium carbonate, and EC values, the studied springs are suitable for agricultural purposes.     

Chemical Composition of Dew Resulting from Radiative Cooling at a Semi-arid Site in Agra, India

Dew samples were collected between October 2007 and February 2008 from a suburban site in Agra. pH, conductivity, major inorganic ions (F^?, Cl^?, NO ₃ ^? , SO ₄ ^2? , Na⁺, K⁺, Ca²⁺, Mg²⁺, and NH ₄ ⁺ ), and some trace metals (Cr, Sn, Zn, Pb, Cd, Ni, Mn, Fe, Si, Al, V, and Cu) were determined to study the chemistry of dew water. The mean pH was 7.3, and the samples exhibited high ionic concentrations. Dew chemistry suggested both natural and anthropogenic influences, with acidity being neutralized by atmospheric ammonia and soil constituents. Ion deposition flux varied from 0.25 to 3.0?neq?m^?2?s^?1, with maximum values for Ca²⁺ followed by NH ₄ ⁺ , Mg²⁺, SO ₄ ^2? , Cl^?, NO ₃ ^? , Na⁺, K⁺, and F^?. Concentrations of trace metals varied from 0.13 to 48?μg?l^?1 with maximum concentrations of Si and minimum concentration of Cd. Correlation analysis suggested their contributions from both crustal and anthropogenic sources.     

Dynamics of the ionospheric electric currents and auroral luminosity boundaries during strong magnetic storms

The regularities in the southward drift of the ionospheric current centers and luminosity boundaries during strong magnetic storms of November 2003 and 2004 (with Dst ≈ ?400 and ?470 nT, respectively) are studied based on the global geomagnetic observations and TV measurements of auroras. It has been indicated that the eastward and westward electrojets in the dayside and nightside sectors simultaneously shift equatorward to minimal latitudes of Φ _min ^° ～53°–55°. It has been obtained that the Φ _min ^° latitude decreases with increasing negative values of Dst, IMF B _z component, and westward electric field strength in the solar wind. The dependence of the electrojet equatorward shift velocity (V _av) on the rate of IMF B _z variations (ΔB _z /Δt) has been determined. It is assumed that the electrojet dynamics along the meridian is caused by a change in the structure of the magnetosphere and electric fields in the solar wind and the Earth’s magnetosphere.     

Seasonal features in the response of the mesopause temperature and emission intensities to solar activity variations

The seasonal dependences of the response of the hydroxyl ((6–2) band) and molecular oxygen O₂(b ¹Σ _g ⁺ ) ((0–1) band) emission intensities, temperature, and density indicator in the region of the hydroxyl emission maximum (87 km) to solar activity have been obtained based on the spectral observations of the mesopause emissions at Zvenigorod observatory during 2000–2007. The ratio of the OH (7–3) and (9–4) band intensities, characterizing the behavior of the vibrational temperature, has been used as an indicator of density. It has been established that the response of the studied mesopause characteristics to solar activity is positive in all seasons. In winter the response is maximal in the intensities and temperature and is minimal in the density indicator. The main mechanisms by which solar activity affects the mesopause characteristics have been considered. The behavior of the internal gravity waves with periods of 0.33–7 h depending on solar activity has been studied. It has been noted that these waves become more active at a minimum of the 11-year solar cycle.     

Secular variation in aerosol transparency of the atmosphere as the possible link between long-term variations in solar activity and climate

Information about variations in solar activity and climate on the time intervals from 130 years to four–five last centuries, including results of instrumental measurements (Wolf numbers, actinometry, thermometry) and indirect indicators (ice core acidity, NO ₃ ^? ion concentration in polar ice, temperature tree-ring reconstructions), has been analyzed for the Northern Hemisphere and its high-latitude part. It has been obtained that the observed relation between secular variations in solar activity and near-Earth temperature resulted from the effect of the corresponding variation in aerosol transparency of the stratosphere on terrestrial climate. It has been also indicated that long-term variations in the aerosol content of the stratosphere can, in turn, be related to secular cycles in atmospheric ionization caused by variations in fluxes of ionizing cosmic particles.     

Temporal trends of bulk precipitation and stream water chemistry (1977–1997) in a small forested area,Krusné hory,northern Bohemia,Czech Republic

The Krusné hory (Erzgebirge or Ore Mountains) has been heavily affected by high atmospheric pollutant deposition caused by fossil fuel combustion in an adjacent Tertiary coal basin. Long‐term routine sampling of bulk precipitation (1977–1996) and stream water (1977–1998) in a forested area on the south‐eastern slope of the mountains were used to evaluate trends and patterns in solute concentration and flux with respect to controlling processes. From 1977 to 1996, the annual volume‐weighted Ca²⁺ and SOconcentrations decreased in bulk precipitation. However, after 1989, when a pronounced and continuous decrease occurred in coal production, annual volume‐weighted concentrations decreased for most solutes, except H⁺. The concentration decreases were marked, with 1996 levels at or below 50% of those in 1989. The lack of a trend in H⁺ is attributed to similar decreases in both acid anions and neutralizing base cations. Stream water concentrations of most solutes, i.e. H⁺, Ca²⁺, Mg²⁺, SONOwere highest at the onset of sampling in 1977, decreased markedly from 1977 to 1983 and decreased more gradually from 1983 to 1998. The spruce forest die‐back and removal reduced dry deposition of these solutes by reducing the filtering action, which was provided by the forest canopy. A notable decrease in stream water Ca²⁺ concentrations occurred after 1995 and may be due to the depletion of Ca²⁺, which was provided by catchment liming in 1986, 1988 and 1989. Solute flux trends in bulk atmospheric deposition and stream water generally were not significant and the lack of trend is attributed to the large interannual variability in precipitation quantity and runoff, respectively. All solutes except Na⁺ varied seasonally. The average seasonal concentrations varied between the solutes, but for most solutes were highest in winter and spring and lowest in summer, correlating with the seasonal trend in runoff. For Ca²⁺, Mg²⁺ and SOthe concentration minimum occurs in September and the maximum occurs in February or March, correlating with the seasonal baseflow. These solutes are primarily controlled by the contribution of soil water and groundwater to stream flow. During snowmelt, the meltwater generally causes concentrations to decrease as soil water and groundwater are diluted. For NO₃ , average minimum concentrations occur in August at the end of the growing season concurrent with the lowest stream flow, and the maximum occurs in February and March with high stream flow during snowmelt. Seasonal stream water NOconcentration variations are large compared with the long‐term decrease. Copyright © 1999 John Wiley & Sons, Ltd.     

Hydrology and nutrient dynamics of spring of almora-binsar area, indian central himalaya: Landscapes, practices, and management

The study aims to measure the hydrological behavior and nutrients dynamics of the springs located in different landscapes of Kosi basin, Indian central Himalaya. A total number of eight springs were considered for the present investigation, each landscape represented by one spring. The monitoring for hydrological measurement was conducted in January 1998 to December 1999, the interval between two successive measurements was 10 days, i.e., 240 hr (total 72 observations were made). Water quality measurement was done in three main seasons, i.e., winter (Jan.), summer (June) and monsoon (Aug.) of 1998 and 1999, and the average value for measured parameters were calculated. These samples were analyzed for pH, electrical conductivity, total dissolved solids, dissolve oxygen, Ca^2?, Mg^2?, Na^?, Cl^?, F^?, NO ₃ ^? , and SO ₄ ^2? . Hydrology of spring’s water showed that the reserve forest has a higher water retention capacity than the other landscapes, and the spring recharge capacity highly influenced by the settlements, open grazing, mismanaged agricultural and deforestation activities. The spring water chemistry shows that the springs located in forest and sparsely populated areas have lower EC, TDS, cationic and anionic concentration and are safe for drinking purposes, but those in irrigated land and densely populated areas feature higher EC, low dissolved oxygen concentration and higher NO ₃ ^? , which makes the water of these springs unsuitable for drinking. F concentration was higher in the springs located in the settlement area. In brief, the study indicates that the unmanaged drains, very poor and old pattern of sewage disposing system result in an increase in Na^?, Cl^?, F^?, NO ₃ ^? , and SO ₄ ^2? concentration as compared to the springs in agricultural and forested areas. All of the studied springs are badly managed which a is great threat for the longevity and quality of the water bodies, in particular, in Indian Central Himalayan region. This study suggests the ways of the constructional works, grazing. Forest resource extraction and agricultural activities in water bodies catchments area should also be controlled.     

Groundwater-derived contaminant fluxes along a channelized Coastal Plain stream

Recent studies in various settings across eastern North America have examined the movement of volatile organic compound (VOC) plumes from groundwater to streams, but few studies have addressed focused discharge of such plumes in unlithified sediments. From 1999 through 2002, we monitored concentrations of trichloroethene (TCE) and the non-volatile co-contaminant technetium-99 (⁹⁹Tc) along Little Bayou Creek, a first-order perennial stream in the Coastal Plain of western Kentucky. Spring flow contributed TCE and ⁹⁹Tc to the creek, and TCE concentrations tended to vary with ⁹⁹Tc in springs. Contaminant concentrations in stream water fluctuated seasonally, but not always synchronously with stream flow. However, contaminant influxes varied seasonally with stream flow and were dominated by a few springs. Concentrations of O₂, , and , values of δ³⁷Cl_DOCl in groundwater, and the lack of less-chlorinated ethenes in groundwater and stream water indicated that anaerobic biodegradation of TCE was unlikely. Losses of TCE along Little Bayou Creek resulted mainly from volatilization, in contrast to streams receiving diffuse contaminated discharge, where intrinsic bioremediation of VOCs appears to be prevalent.     

Genetic features of gas-condensate reservoirs in the Kekeya Field,southwest depression in the Tarim Basin,China

Oils, condensates and natural gases in the Kekeya Field, southeast depression of the Tarim Basin were studied for their geochemical characteristics. According to the distribution analysis of the C₂/C₃ values with C₁/C₂ values, C₂/C₃ values with C₁/C₃ values, as well as C₂/C₃ values with dryness index, there are two different types of natural gases in the studied field, which are spatially regularly distributed. One is the oil cracking gas, located on shallow reservoirs over X ₅ ² reservoir, namely Upper oil legs; the other is kerogen cracking gas, located on X ₇ ² reservoirs, X₈ reservoirs and E₂ k reservoirs, namely Lower oil legs. In addition, the distribution patterns of molar concentration of oils and condensates with different carbon numbers of the n-alkanes in the Kekeya Field indicate that the crude oils have experienced several kinds of secondary alterations, which were closely related to the charging of gaseous hydrocarbons after petroleum accumulation. These results indicate that, based on the research of δ ¹³C values of individual hydrocarbons, heptane values and isoheptane values of light hydrocarbons and aromatic maturity parameters for oils, condensates and natural gases, oils and gases were charged at different geological time in the Kekeya Field.     

Interannual variability of the air–sea CO2 flux in the north Indian Ocean

A simple biogeochemical model coupled to an offline ocean tracer transport model driven by reanalysis ocean data is used to simulate the seasonal and interannual CO $_2$ flux variability in the northern Indian Ocean. The maximum of seasonal and interannual CO $_2$ emission variances in the northern Indian Ocean are located in the coastal Arabian Sea (AS) and Southern Peninsular India (SP) with a basin-wide seasonal amplitude and standard deviation of 0.044 $\pm $ 0.04 Pg C year $^{-1}$ . The area integrated CO $_2$ emissions from these two regions in the model are significantly correlated (above a 95 % level) with the observations of Takahashi et al. (Deep-Sea Res-II, 56:554–577, 2009). The interannual anomalies of CO $_2$ emission from the AS and SP are found as 40 and 30 % of their respective seasonal amplitudes. Both the Arabian Sea (AS) and Southern Peninsular India (SP) interannual CO $_2$ emission anomalies show a 3–4-year variability. The correlations of AS and SP CO $_2$ emission anomalies with the Indian Ocean Dipole/Zonal Mode (IODZM) and Southern Oscillation (SO) indices from 1980 to 1999 are 0.35, 0.21 and 0.32, 0.01 respectively. A 5-year window moving correlation analysis shows that the relationship of AS and SP CO $_2$ emission to the SO and IODZM are complementary to each other. During the years when the correlation of air–sea CO $_2$ emission with the IODZM is stronger, the corresponding correlation with the SO is weaker or opposite. The total change in pCO $_2$ is broken down into changes induced by the individual components such as dissolved inorganic carbon (DIC), sea surface temperature (SST), alkalinity, and salinity and found that (1) the effect of SST in the AS CO $_2$ emission increases (decreases) when the correlation of CO $_2$ emission with the IODZM is positive (negative), and (2) the SP CO $_2$ emission is strongly controlled by the circulation-driven DIC changes; however, this relation is found to be weaker when the SO correlates negatively with the SP CO $_2$ emission.     

Singlet oxygen O2(b1Σ g + ) production at altitudes of the polar ionosphere

The relative rate constants of O₂(b¹Σ _g ⁺ , v= 1–4) production at an inelastic interaction between electronically excited N(²D) atoms and O₂(X³Σ _g ^? , v = 0) oxygen molecules have been calculated. It was shown that an increase in equilibrium distances between oxygen atoms in NO₂ quasi-molecule, produced during the interaction, substantially increases the calculated relative production rates of O₂(b¹Σ _g ⁺ , v > 1). The obtained coefficients are used to calculate the O₂(b¹Σ _g ⁺ , v= 1–4) relative populations at 110 km (T = 250 K) and 150 km (T = 500 K) altitudes of the polar ionosphere. The calculated populations have been compared with the results of the published measurements of the Atmospheric system band luminosity intensities, and satisfactory agreement has been obtained for low altitudes.     

Dependence of the chemical composition of thermal waters upon seismic activity

Changes in the chemical composition of the hot springs of Mendeleev Volcano (Kunashir Island) as for Cl^?, SO ₄ ^2? , CO₂, NH ₄ ⁺ and Cl^?/SO ₄ ^2? are given in function of the 1965–66 and 1973 (in part) seismic activity in the South Kurile islands.     

Refraction of the principal stress trajectories and the stress jumps on faults and contact surfaces: Part 1. Non-constrained regular trajectories

Rock masses contain ubiquitous multiscale heterogeneities, which (or whose boundaries) serve as the surfaces of discontinuity for some characteristics of the stress state, e.g., for the orientation of principal stress axes. Revealing the regularities that control these discontinuities is a key to understanding the processes taking place at the boundaries of the heterogeneities and for designing the correct procedures for reconstructing and theoretical modeling of tectonic stresses. In the present study, the local laws describing the refraction of the axes of extreme principal stresses T ₁ (maximal tension in the deviatoric sense) and T ₃ (maximal compression) of the Cauchy stress tensor at the transition over the elementary area n of discontinuity whose orientation is specified by the unit normal n are derived. It is assumed that on the area n of discontinuity, frictional contact takes place. No hypotheses are made on the constitutive equations, and a priori constraints are not posed on the orientation on the stress axes. Two domains, which adjoin area n on the opposite sides and are conventionally marked + and ?, are distinguished. In the case of the two-dimensional (2D) stress state, any principal stress axis on passing from domain ? to domain + remains in the same quadrant of the plane as the continuation of this axis in domain +. The sign and size of the refraction angle depend on the sign and amplitude of the jump of the normal stress, which is tangential to the surface of discontinuity. In the three-dimensional (3D) case, the refraction of axes T ₁ and T ₃ should be analyzed simultaneously. For each side, + and ?, the projections of the T ₁ and T ₃ axes on the generally oriented plane n form the shear sectors S ⁺ and S ^?, which are determined unambiguously and to whose angular domains the possible directions p ⁺ and p ^? of the shear stress vectors belong. In order for the extreme stress axes T ₁ ⁺ ,T ₃ ⁺ and T ₁ ^? , T ₃ ^? to be statically compatible on the generally oriented plane n, it is required that sectors S ⁺ and S ^? had a nonempty intersection. The direction vectors p ⁺ and p ^? are determined uniquely if, besides axes T ₁ ^? , T ₃ ^? and T ₁ ⁺ , T ₃ ⁺ , also the ratios of differential stresses R ⁺ and R ^? (0 ≤ R ^± ≤ 1) are known. This is equivalent to specifying the reduced stress tensors T _R ⁺ and T _R ^? The necessary condition for tensors T _R ⁺ and T _R ^? being statically compatible on plane n is the equality p ⁺ = p ^?. In this paper, simple methods are suggested for solving the inverse problem of constructing the set of the orientations of the extreme stress axes from the known direction p of the shear stress vector on plane n and from the data on the shear sector. Based on these methods and using the necessary conditions of local equilibrium on plane n formulated above, all the possible orientations of axes T ₁ ⁺ , T ₃ ⁺ are determined if the projections of axes T ₁ ^? , T ₃ ^? axes on side — are given. The angle between the projections of axes T ₁ ⁺ , T ₁ ^? and/or T ₃ ⁺ , T ₃ ^? on the plane can attain 90°. Besides the general case, also the particular cases of the contact between the degenerate stress states and the special position of plane n relative to the principal stress axes are thoroughly examined. Generalization of the obtained results makes it possible to plot the local diagram of the orientations of axes T ₁ ⁺ , T ₃ ⁺ for a given sector S ^?. This diagram is a so-called stress orientation sphere, which is subdivided into three pairs of areas (compression, tension, and compression-extension). The tension and compression zones cannot contain the poles of T ₃ ⁺ and T ₁ ⁺ axes, respectively. The compression-extension zones can contain the poles of either T ₁ ⁺ or T ₃ ⁺ axis but not both poles simultaneously. In the particular case when the shear stress vector has a unique direction p ^? on side ?, the areas of compression-extension disappear and the diagram is reduced to a beach-ball plot, which visualizes the focal mechanism solution of an earthquake. If area n is a generally oriented plane and if the orientation of the pairs of the statically compatible axes T ₁ ^? , T ₃ ^? and T ₁ ⁺ , T ₃ ⁺ is specified, then, the stress values on side + are uniquely determined from the known stress values on side ?. From the value of differential stress ratio R ^?, one can calculate the value of R ⁺, and using the values of the principal stresses on side ?, determine the total stress tensor T ⁺ on side +. The obtained results are supported by the laboratory experiments and drilling data. In particular, these results disclose the drawbacks of some established notions and methods in which the possible refraction of the stress axes is unreasonably ignored or taken into account improperly. For example, it is generally misleading to associate the slip on the preexisting fault with the orientation of any particular trihedron of the principal stress axes. The reconstruction should address the potentially statically compatible principal stress axes, which are differently oriented on opposite sides of the fault plane. The fact that, based on the orientation of the intraplate principal stresses at the base of the lithosphere, one cannot make a conclusion on the active or passive influence of the mantle flows on the lithospheric plate motion is another example. The present relationships linking the stress values on the opposite sides of the fault plane on which the orientations of the principal stress axes are known demonstrate the incorrectness of the existing methods, in which the reduced stress tensors within the material domains are reconstructed without allowance for the dynamic interaction of these domains with their neighbors. In addition, using the obtained results, one can generalize the notion of the zone of dynamical control of a fault onto the case of the existence of discontinuities in this region and analyze the stress transfer across the system of the faults.     

The role of the SO2 oxidation for the background stratospheric sulfate layer in the light of new reaction rate data

Presently available data on the reaction of SO₂ with OH radicals (OH + SO₂ + \(M\xrightarrow[{k_1 }]{}\) HSO₃ +M) are critically reviewed in light of recent stratospheric sulfur budget calculations. These calculations impose that the net oxidation ratek of SO₂ within the stratosphere should fall within the range 10^?7≤k≤10^?9, if the SO₂ oxidation model for the stratospheric sulfate layer is assumed to be correct. The effective reaction rate constantk ₁ ^* =k ₁[M] at the stratospheric temperature is estimated as $$k_1^* = \frac{{(8.2 \pm 2.2) \times 10^{ - 13} \times [M]}}{{(0.79 \mp 0.34) \times 10^{ - 13} + [M]}}cm^3 /molecules sec$$ where [M] refers to the total number density (molecules/cm³). Using the above limiting values ofk ₁ ^* , and the estimated OH density concentrations, the net oxidation rate is calculated as 3.6×10^?7≤k≤1.3×10^?8 at 17 km altitude. This indicates that the upper limit of thesek values exceeds the tolerable range imposed by the model by a factor of about four. Obviously the uncertainty of thek ₁ ^* values and of the OH concentrations in the stratosphere is still too large to make definite conclusions on the validity of the SO₂ model.     

The TKE dissipation rate in the northern South China Sea

The microstructure measurements taken during the summer seasons of 2009 and 2010 in the northern South China Sea (between 18°N and 22.5°N, and from the Luzon Strait to the eastern shelf of China) were used to estimate the averaged dissipation rate in the upper pycnocline 〈ε _p〉 of the deep basin and on the shelf. Linear correlation between 〈ε _p〉 and the estimates of available potential energy of internal waves, which was found for this data set, indicates an impact of energetic internal waves on spatial structure and temporal variability of 〈ε _p〉. On the shelf stations, the bottom boundary layer depth-integrated dissipation $ {\widehat{\varepsilon}}_{\mathrm{BBL}} $ reaches 17–19 mW/m², dominating the dissipation in the water column below the surface layer. In the pycnocline, the integrated dissipation $ {\widehat{\varepsilon}}_{\mathrm{p}} $ was mostly ～10–30 % of $ {\widehat{\varepsilon}}_{\mathrm{BBL}} $ . A weak dependence of bin-averaged dissipation $ \overline{\varepsilon} $ on the Richardson number was noted, according to $ \overline{\varepsilon}={\varepsilon}_0+\frac{\varepsilon_{\mathrm{m}}}{{\left(1+ Ri/R{i}_{\mathrm{cr}}\right)}^{1/2}} $ , where ε ₀ + ε _m is the background value of $ \overline{\varepsilon} $ for weak stratification and Ri _cr?=?0.25, pointing to the combined effects of shear instability of small-scale motions and the influence of larger-scale low frequency internal waves. The latter broadly agrees with the MacKinnon–Gregg scaling for internal-wave-induced turbulence dissipation.     

Scaling Transition in Earthquake Sources: A Possible Link Between Seismic and Laboratory Measurements

We estimate the corner frequencies of 20 crustal seismic events from mainshock–aftershock sequences in different tectonic environments (mainshocks 5.7 < M _W < 7.6) using the well-established seismic coda ratio technique (Mayeda et al. in Geophys Res Lett 34:L11303, 2007; Mayeda and Malagnini in Geophys Res Lett, 2010), which provides optimal stability and does not require path or site corrections. For each sequence, we assumed the Brune source model and estimated all the events’ corner frequencies and associated apparent stresses following the MDAC spectral formulation of Walter and Taylor (A revised magnitude and distance amplitude correction (MDAC2) procedure for regional seismic discriminants, 2001), which allows for the possibility of non-self-similar source scaling. Within each sequence, we observe a systematic deviation from the self-similar \( M_{0} \propto \mathop f\nolimits_{\text{c}}^{ - 3} \) line, all data being rather compatible with \( M_{0} \propto \mathop f\nolimits_{\text{c}}^{ - (3 + \varepsilon )} \) , where ε > 0 (Kanamori and Rivera in Bull Seismol Soc Am 94:314–319, 2004). The deviation from a strict self-similar behavior within each earthquake sequence of our collection is indicated by a systematic increase in the estimated average static stress drop and apparent stress with increasing seismic moment (moment magnitude). Our favored physical interpretation for the increased apparent stress with earthquake size is a progressive frictional weakening for increasing seismic slip, in agreement with recent results obtained in laboratory experiments performed on state-of-the-art apparatuses at slip rates of the order of 1 m/s or larger. At smaller magnitudes (M _W < 5.5), the overall data set is characterized by a variability in apparent stress of almost three orders of magnitude, mostly from the scatter observed in strike-slip sequences. Larger events (M _W > 5.5) show much less variability: about one order of magnitude. It appears that the apparent stress (and static stress drop) does not grow indefinitely at larger magnitudes: for example, in the case of the Chi–Chi sequence (the best sampled sequence between M _W 5 and 6.5), some roughly constant stress parameters characterize earthquakes larger than M _W ~ 5.5. A representative fault slip for M _W 5.5 is a few tens of centimeters (e.g., Ide and Takeo in J Geophys Res 102:27379–27391, 1997), which corresponds to the slip amount at which effective lubrication is observed, according to recent laboratory friction experiments performed at seismic slip velocities (V ~ 1 m/s) and normal stresses representative of crustal depths (Di Toro et al. in Nature in press, 2011, and references therein). If the observed deviation from self-similar scaling is explained in terms of an asymptotic increase in apparent stress (Malagnini et al. in Pure Appl Geophys, 2014, this volume), which is directly related to dynamic stress drop on the fault, one interpretation is that for a seismic slip of a few tens of centimeters (M _W ~ 5.5) or larger, a fully lubricated frictional state may be asymptotically approached.