Effects of elevated CO2 on the reproduction of two calanoid copepods

Some planktonic groups suffer negative effects from ocean acidification (OA), although copepods might be less sensitive. We investigated the effect of predicted CO₂ levels (range 480–750 ppm), on egg production and hatching success of two copepod species, Centropages typicus and Temora longicornis. In these short-term incubations there was no significant effect of high CO₂ on these parameters. Additionally a very high CO₂ treatment, (CO₂ = 9830 ppm), representative of carbon capture and storage scenarios, resulted in a reduction of egg production rate and hatching success of C. typicus, but not T. longicornis. In conclusion, reproduction of C. typicus was more sensitive to acute elevated seawater CO₂ than that of T. longicornis, but neither species was affected by exposure to CO₂ levels predicted for the year 2100. The duration and seasonal timing of exposures to high pCO₂, however, might have a significant effect on the reproduction success of calanoid copepods.     

Use of a harpacticoid copepod in toxicity tests

The harpacticoid copepod Nitocra spinipes has been tested for acute toxicity of 12 metal chlorides in brackish water. Their order of toxicity, expressed as 96 h LC₅₀, was in good agreement with other investigations performed in freshwater and seawater. The 96 h LC₅₀-values were of intermediate levels compared to these two environments. The organochlorines p,p′-DDE and p,p′-DDE methyl sulphone were tested for effects on reproduction and mortality during two weeks, and it was found that p,p′-DDE was the most toxic. It is concluded from the investigation that N. spinipes is a suitable toxicity test organism in brackish water.     

Effect of prolonged hypoxia on food consumption,respiration, growth and reproduction in marine scavenging gastropod Nassarius festivus

The effects of prolonged exposure to reduced oxygen levels (3.0 and 1.5 mg O₂ l⁻¹) on marine scavenging gastropods Nassarius festivus were studied for 8 weeks. The percentages of individuals engaged in feeding and amount of food consumed were reduced as oxygen level decreased; absorption efficiency, however, did not vary significantly with oxygen level. Oxygen consumption rates and specific oxygen consumption rates were lower at reduced oxygen levels. Reproduction occurred at all oxygen levels with less egg capsules being produced at lower oxygen levels. Egg size and number of eggs per capsule, however, were not significantly affected by oxygen level. The increase in shell length was 12%, 6% and 5% at 6.0 mg O₂ l⁻¹ (normoxia), 3.0 mg O₂ l⁻¹ and 1.5 mg O₂ l⁻¹, respectively. At the end of the experiment, the amount of energy allocated to growth and reproduction decreased at reduced oxygen levels with values obtained at 3.0 mg O₂ l⁻¹ and 1.5 mg O₂ l⁻¹ being 48% and 70% lower than those at 6.0 mg O₂ l⁻¹. At all oxygen levels, most of the accumulated energy was allocated to shell growth and reproduction, and the amount allocated to somatic growth was relatively insignificant. The reduction in energy allocated to reproduction was greater than that to shell growth as the oxygen level was reduced, indicating a strategic energy allocation of marine scavengers under stressful conditions to enhance survival.     

Evaluating BOD and the coefficient of oxidation rate: Monitoring,direct and inverse problems,formulas, calculations and tables

It is proposed to evaluate two theoretical characteristics, i.e., BOD (biochemical oxygen demand) and k ₀ (the coefficient of oxidation rate by new formulas based on two experimental variables: BOD _T and BOD_2T (biochemical oxygen consumption in two periods T and 2T day, respectively). The formulation and an analytical solution are given for a direct problem describing the process of biochemical oxidation of organic matter (OM) in a water volume in the absence of aeration (e.g., in a water body under ice or in a sealed flask used to measure biochemical oxygen consumption). The problem is solved based on the closed (modified) Streeter–Phelps system. Unlike the classical Streeter–Phelps system, the closed system excludes physically incorrect solutions (e.g., negative concentrations of dissolved oxygen (DO)) [4]. The solution of the direct problem is used to formulate an inverse problem, whose solution is given in the form of formulas for evaluating BOD and k ₀. These formulas are used to compile tables to illustrate the essence of the proposed method.     

Studying local sources in the radio range based on the partial solar eclipse of January 4, 2011, at the Mountain Astronomical Station, Central Astronomical Observatory, Russian Academy of Sciences

Data are presented on a partial solar eclipse, which occurred on January 4, 2011, and was observed with RT-3 (?? = 4.9 cm) and RT-2 (?? = 3.2 cm) radio telescopes at the Mountain Astronomical Station, Central Astronomical Observatory, Russian Academy of Sciences (MAS CAO RAS). The radioemission flux in two channels was registered using digital methods with a time resolution of 0.5 s. Comparisons were performed with observations in the optical, UV, and X-ray ranges. The following local sources of increased radioemission on the solar disk have been identified: sunspot groups 1 (NOAA 1142) and 126 (NOAA 1141), unipolar sunspot 127 (NOAA 1140), facula areas, and polar and midlatitude coronal holes. It has been indicated that the brightness of a unipolar sunspot (for ?? = 4.9 cm, I _rel = 29.5; for ?? = 3.2 cm, I _rel = 10.1) and two sunspot groups (for ?? = 4.9 cm, I _rel = 10.1 and 14.2; for ?? = 3.2 cm, I _rel = 5.1 and 6.2) is maximal. The radioemission flux of all found coronal holes is decreased, and the decrease is more contrasting in the 4.9-cm range as compared to such a decrease in the 3.2-cm range. Radio maps of the Sun and changes in the radioemission flux of undisturbed solar regions from the center to the limb for ?? = 4.9 and 3.2 cm have been constructed based on the eclipse data.     

Tidal dynamics of the Terminos Lagoon,Mexico: observations and 3D numerical modelling

The tidal circulation patterns in the Terminos Lagoon were studied based on the analysis of 1 year of measurements and numerical simulations using a baroclinic 3D hydrodynamic model, the MARS3D. A gauging network was installed consisting of six self-recording pressure–temperature sensors, a tide gauge station and two current profilers, with pressure and temperature sensors moored in the main lagoon inlets. Model simulations were validated against current and sea level observations and were used to analyse the circulation patterns caused by the tidal forcing. The numerical model was forced with eight harmonic components, four diurnal (K ₁, O ₁, P ₁, Q ₁) and four semi-diurnal (M ₂, S ₂, N ₂, K ₂), extracted from the TPX0.7 database. The tidal patterns in the study area vary from mixed, mainly diurnal in the two main inlets of the lagoon, to diurnal in its interior. The tidal residual circulation inside the lagoon is dominated by a cyclonic gyre. The results indicate a net flux from the southwest Ciudad del Carmen inlet (CdC) towards the northeast Puerto Real inlet (PtR) along the southern side of the lagoon and the opposite in the northern side. The results indicate two areas of strong currents in the vicinity of the inlets and weak currents inside the lagoon. The area of strong currents in the vicinity of the CdC inlet is larger than that observed in the PtR inlet. Nevertheless, the current analysis indicates that the highest current speeds, which can reach a magnitude of 1.9 m s^?1, occurred in PtR. A further analysis of the tide distortion in the inlets revealed that both passages are ebb dominated.     

Analogue model,relating Kp index to solar wind parameters

In a previous work the authors have developed a model, providing K_p as a function of the interplanetary magnetic field B_z component. They introduced a modified B_z function (denoted as B_zm), exhibiting a delayed reaction to B_z changes. The modified function B_zm was defined by using the analogy with a damping RC-circuit output voltage. The delaying reaction of B_zm to B_z was characterized by two time constants, one for rising and one for decreasing parts of B_z. The cross-correlation between K_p and B_zm has increased to 0.7, compared with −0.4 between K_p and B_z. In this paper, new dependences of K_p on solar wind velocity and dynamic pressure are included in the model to improve its accuracy. These solar wind parameters are found to correlate best with K_p. The hourly interpolated values are also added to the 3-h K_p values to increase the statistics. The new K_p data set is denoted as K_p1. The mean dependence of K_p on B_zm and dynamic pressure are approximated with parabolas, while the dependence on the velocity is linear. The constants in the model expression are obtained by using ACE data (1998–2000). The overall model error is estimated at 0.63 units K_p. The improvement over the previous simpler dependence in terms of the model error is about 30%.     

Cellular energy allocation in mussels (Mytilus galloprovincialis) from the stratified estuary as a physiological biomarker

This study demonstrates the usefulness of cellular energy allocation (CEA) evaluations as a physiological biomarker to infer the occurrence of natural stress in native populations of mussels inhabiting the stratified estuary (Krka River estuary, Croatia). Sampling sites were selected based on their differences in the salinity and temperature. The CEA value was calculated as a ratio between available energy (E_a) and energy consumption (E_c). Generally, higher values of E_a were recorded in June than in November, which were especially evident in the storage components (carbohydrates and lipids), while the constitutive component (proteins) remained relatively constant. The highest E_c was recorded in mussels at estuarine site compared to coastal site, which may be caused by the energetically costly maintenance of osmotic balance. Decrease in CEA recorded in estuarine mussels may ultimately result in a lower amount of energy available for growth, reproduction, or defence against other stresses (e.g. pollution).     

Crustal Heterogeneity and Seismotectonics of the National Capital Region, Delhi, India

To better understand the relationship between crustal heterogeneity and seismotectonics in the National Capital Region (NCR), Delhi, India, we carried out local P- and S-velocity tomography beneath the NCR. First arrival times of the first P- and S-wave from 275 crustal earthquakes recorded by the Seismic Telemetry Network in and around Delhi of the India Meteorological Department, India, are inverted to obtain crustal P-, S-velocity and V _P /V _S variations in the region. Our tomographic images of the upper crust reflect well the surface geological and tectonic features. The Delhi fold belt is identified as low V _P, high V _S and low V _P/V _S. The Sohna hot spring region is appearing as low V _P, low V _S and high V _P /V _S correlating with the possible presence of fluid-filled rocks. The crustal seismicity is distributed in both the high- and low-velocity zones, but most distinctly in the low V _P /V _S region.     

Eutrophication and warming-driven green tides (Ulva rigida) are predicted to increase under future climate change scenarios

The incidence and severity of extraordinary macroalgae blooms (green tides) are increasing. Here, climate change (ocean warming and acidification) impacts on life history and biochemical responses of a causative green tide species, Ulva rigida, were investigated under combinations of pH (7.95, 7.55, corresponding to lower and higher pCO₂), temperature (14, 18 °C) and nitrate availability (6 and 150 μmol L^? 1). The higher temperature accelerated the onset and magnitude of gamete settlement. Any two factor combination promoted germination and accelerated growth in young plants. The higher temperature increased reproduction, which increased further in combination with elevated pCO₂ or nitrate. Reproductive success was highest (64.4 ± 5.1%) when the upper limits of all three variables were combined. Biochemically, more protein and lipid but less carbohydrate were synthesized under higher temperature and nitrate conditions. These results suggest that climate change may cause more severe green tides, particularly when eutrophication cannot be effectively controlled.     

Geologic Setting, Field Survey and Modeling of the Chimbote, Northern Peru, Tsunami of 21 February 1996

—Whereas the coast of Peru south of 10°S is historically accustomed to tsunamigenic earthquakes, the subduction zone north of 10°S has been relatively quiet. On 21 February 1996 at 21:51 GMT (07:51 local time) a large, tsunamigenic earthquake (Harvard estimate M _w = 7.5) struck at 9.6°S, 79.6°W, approximately 130 km off the northern coast of Peru, north of the intersection of the Mendaña fracture zone with the Peru–Chile trench. The likely mechanism inferred from seismic data is a low-angle thrust consistent with subduction of the Nazca Plate beneath the South American plate, with relatively slow rupture characteristics. Approximately one hour after the main shock, a damaging tsunami reached the Peruvian coast, resulting in twelve deaths. We report survey measurements, from 7.7°S to 11°S, on maximum runup (2–5m, between 8 and 10°S), maximum inundation distances, which exceeded 500 m, and tsunami sediment deposition patterns. Observations and numerical simulations show that the hydrodynamic characteristics of this event resemble those of the 1992 Nicaragua tsunami. Differences in climate, vegetation and population make these two tsunamis seem more different than they were. This 1996 Chimbote event was the first large (M _w >7) subduction-zone (interplate) earthquake between about 8 and 10°S, in Peru, since the 17th century, and bears resemblance to the 1960 (M _w 7.6) event at 6.8°S. Together these two events are apparently the only large subduction-zone earthquakes in northern Peru since 1619 (est. latitude 8°S, est. M _w 7.8); these two tsunamis also each produced more fatalities than any other tsunami in Peru since the 18th century. We concur with Pelayo and Wiens (1990, 1992) that this subduction zone, in northern Peru, resembles others where the subduction zone is only weakly coupled, and convergence is largely aseismic. Subduction-zone earthquakes, when they occur, are slow, commonly shallow, and originate far from shore (near the tip of the wedge). Thus they are weakly felt, and the ensuing tsunamis are unanticipated by local populations. Although perhaps a borderline case, the Chimbote tsunami clearly is another wake-up example of a "tsunami earthquake."     

A study in the velocity structure of December 5, 1997, M w = 7.8 Kronotskii rupture zone, Kamchatka

The object of the present study was to obtain and investigate the 3D velocity structure of the rupture zone of a large earthquake, to be specific, the great ( _Mw = 7.8) Kronotskii earthquake that occurred in Kamchatka on December 5, 1997. The event was preceded by a foreshock swarm (December 3–5, 1997) and followed by a long aftershock sequence. We investigated the V _P velocity distribution for different time periods: December 3–7, 1997 (when the chief events occurred, viz., the main shock and the larger aftershocks) and for subsequent periods of decaying aftershock activity until December 1998. The velocity distribution in the rupture zone proved to be inhomogeneous. Three regions have been identified: the northeastern (the main shock and foreshocks), the central, and the southwestern, which differ both in the character of seismicity and in velocity. The V _P distribution was found to be time-dependent. The velocity was below the standard values in the foreshock-aftershock area in December 1997, subsequently the velocity increased. These results may indicate the absence of a continuous rupture zone, with the main shock and the two largest aftershocks that occurred in the southwest probably being independent events rupturing a transverse fault during the stress rearrangement following the main shock.     

Negative correlation between porosity and hydraulic conductivity in sand-and-gravel aquifers at Cape Cod,Massachusetts, USA

Although it may be intuitive to think of the hydraulic conductivity K of unconsolidated, coarse-grained sediments as increasing monotonically with increasing porosity Φ, studies have documented a negative correlation between these two parameters under certain grain-size distributions and packing arrangements. This is confirmed at two sites on Cape Cod, Massachusetts, USA, where groundwater investigations were conducted in sand-and-gravel aquifers specifically to examine the interdependency of several aquifer properties using measurements from four geophysical well logs. Along with K and Φ, the electrical resistivity R₀ and the natural gamma activity γ of saturated deposits were determined as functions of depth. Qualitative examination of results from the first site implies a negative correlation between K and Φ that is substantiated by a rigorous multivariate analysis of log data collected from the second site. A principal components analysis describes an over-determined system of inversion equations, with approximately 92% of the cumulative proportion of the total variance being accounted for by only three of the four eigenvectors. A subsequent R-mode factor analysis projects directional trends among the four variables (K, Φ, R₀ and γ), and a negative correlation between K and Φ emerges as the primary result.     

Effect of prolonged hypoxia on food consumption, respiration, growth and reproduction in marine scavenging gastropod Nassarius festivus

The effects of prolonged exposure to reduced oxygen levels (3.0 and 1.5 mg O₂ l⁻¹) on marine scavenging gastropods Nassarius festivus were studied for 8 weeks. The percentages of individuals engaged in feeding and amount of food consumed were reduced as oxygen level decreased; absorption efficiency, however, did not vary significantly with oxygen level. Oxygen consumption rates and specific oxygen consumption rates were lower at reduced oxygen levels. Reproduction occurred at all oxygen levels with less egg capsules being produced at lower oxygen levels. Egg size and number of eggs per capsule, however, were not significantly affected by oxygen level. The increase in shell length was 12%, 6% and 5% at 6.0 mg O₂ l⁻¹ (normoxia), 3.0 mg O₂ l⁻¹ and 1.5 mg O₂ l⁻¹, respectively. At the end of the experiment, the amount of energy allocated to growth and reproduction decreased at reduced oxygen levels with values obtained at 3.0 mg O₂ l⁻¹ and 1.5 mg O₂ l⁻¹ being 48% and 70% lower than those at 6.0 mg O₂ l⁻¹. At all oxygen levels, most of the accumulated energy was allocated to shell growth and reproduction, and the amount allocated to somatic growth was relatively insignificant. The reduction in energy allocated to reproduction was greater than that to shell growth as the oxygen level was reduced, indicating a strategic energy allocation of marine scavengers under stressful conditions to enhance survival.     

Source time functions of the Gonghe,China earthquake retrieved from long-period digital waveform data using empirical Green’s function technique

An earthquake ofM _S=6.9 occurred at the Gonghe, Qinghai Province, China on April 26, 1990. Three larger aftershocks took place at the same region,M _S=5.5 on May 7, 1990,M _S=6.0 on Jan. 3, 1994 andM _S=5.7 on Feb. 16, 1994. The long-period recordings of the main shock from China Digital Seismograph Network (CD-SN) are deconvolved for the source time functions by the correspondent recordings of the three aftershocks as empirical Green’s functions (EGFs). No matter which aftershock is taken as EGF, the relative source time functions (RSTFs) obtained are nearly identical. The RSTFs suggest theM _S=6.9 event consists of at least two subevents with approximately equal size whose occurrence times are about 30 s apart, the first one has a duration of 12 s and a rise time of about 5 s, and the second one has a duration of 17 s and a rise time of about 8 s. Comparing the RSTFs obtained from P- and SH-phases respectively, we notice that those from SH-phases are a slightly more complex than those from P-phases, implying other finer subevents exist during the process of the main shock. It is interesting that the results from the EGF deconvolution of long-period wavform data are in good agreement with the results from the moment tensor inversion and from the EGF deconvolution of broadband waveform data. Additionally, the two larger aftershocks are deconvolved for their RSTFs. The deconvolution results show that the processes of theM _S=6.0 event on Jan. 3, 1994 and theM _S=5.7 event on Feb. 16, 1994 are quite simple, both RSTFs are single impulses. The RSTFs of theM _S=6.9 main shock obtained from different stations are noticed to be azimuthally dependent, whose shapes are a slightly different with different stations. However, the RSTFs of the two smaller aftershocks are not azimuthally dependent. The integrations of RSTFs over the processes are quite close to each other, i. e., the scalar seismic moments estimated from different stations are in good agreement. Finally the scalar seismic moments of the three aftershocks are compared. The relative scalar seismic moment of the three aftershocks deduced from the relative scalar seismic moments of theM _S=6.9 main shock are very close to those inverted directly from the EGF deconvolution. The relative scalar seismic moment of theM _S=6.9 main shock calculated using the three aftershocks as EGF are 22 (theM _S=6.0 aftershock being EGF), 26 (theM _S=5.7 aftershock being EGF) and 66 (theM _S=5.5 aftershock being EGF), respectively. Deducing from those results, the relative scalar sesimic moments of theM _S=6.0 to theM _S=5.7 events, theM _S=6.0 to theM _S=5.5 events and theM _S=5.7 to theM _S=5.5 events are 1.18, 3.00 and 2.54, respectively. The correspondent relative scalar seismic moments calculated directly from the waveform recordings are 1.15, 3.43, and 3.05.     

Experimental study of the settling of twin spherical particles released side by side: The impact of particle size,fluid viscosity,initial spacing,and particle density

The settling of solid particles in a fluid is an important process that needs to be considered in many fields of research. For example, the interactions among particles and between particles and the surrounding fluid are important topics in studying suspended sediment transport and water clarification. In this paper, the settling processes and interactions of twin spherical particles released side by side were experimentally studied. The Reynolds number varied in the range of 1-300, which is wit...     

Earthquake ground motion predictive equations for Garhwal Himalaya,India

Predictive equations based on the stochastic approach are developed for earthquake ground motions from Garhwal Himalayan earthquakes of 3.5≤M_w≤6.8 at a distance of 10≤R≤250 km. The predicted ground motion parameters are response spectral values at frequencies from 0.25 to 20 Hz, and peak ground acceleration (PGA). The ground motion prediction equations (GMPEs) are derived from an empirically based stochastic ground motion model. The GMPEs show a fair agreement with the empirically developed ground motion equations from Himalaya as well as the NGA equation. The proposed relations also reasonably predict the observed ground motion of two major Himalayan earthquakes from Garhwal Himalayan region. For high magnitudes, there is insufficient data to satisfactorily judge the relationship; however it reasonably predicts the 1991 Uttarkashi earthquake (M_w=6.8) and 1999 Chamoli earthquake (M_w=6.4) from Garhwal Himalaya region.     

The use of Bayesian methods for fitting rating curves,with case studies

Using data from two very large watersheds and five smaller, this paper explores the use of Bayesian methods for fitting rating curves. Posterior distribution of rating-curve parameters were calculated using Markov Chain Monte Carlo (MCMC) methods, and 95% credible intervals were calculated for predicted discharges, given stage. Expected discharge was related to stage using a link function. For the five smaller watersheds, the assumptions were (a) that the distribution of discharge Q, given stage h, is Normal, with variance proportional to h; (b) that a log link function relates μ_Q, the mean of Q∣h, to a function of stage, of the form μ_Q = β(h + α)^λ. For the two large watersheds, however, a better fit was obtained by taking the distribution of Q to be log-Normal, and the link function as ln μ_Q = β₀ + β₁h. For the two large watersheds, priors for all three parameters were taken as uninformative; for the five smaller, the prior for parameter λ was taken as Normally distributed, N(2, 0.5). Acceptable ratings were obtained for all seven sites. It is argued that distributions of derived variables (such as annual maximum discharge) can be derived directly from (a) the posterior distribution of rating-curve parameters, and (b) the stage record, without recourse to additional assumptions. Estimates thus obtained for the T-year event will incorporate rating-curve uncertainty. It is argued that Bayesian methods are appropriate for rating-curve calculation because their inherent flexibility (a) allows the incorporation of prior information about the nature of a rating curve; (b) yields credible intervals for predicted discharges and quantities derived from them; (c) can be extended to allow for uncertainty in stage measurements.     

Pattern recognition of major asperities using local recurrence time in Alborz Mountains, Northern Iran

In this study, seismic data recorded during the period 01/01/1996 to 09/01/2009 has been used to evaluate the seismic hazard potential along the Alborz region, Northern Iran. The technique of mapping local recurrence time, T _L, is used to map major asperities, which are considered as the areas with maximum hazard. We calculated T _L from a and b values which are in turn derived from the frequency–magnitude relation constants within a radius of 30 km about every corner point of a 10-km spacing grid. Since b value is inversely related to applied stress, the areas with lowest b values and/or shortest T _L are interpreted to locate the asperities or the areas of maximum seismic hazard. To test this method, we computed T _L map using seismic catalogues before and after the 2004 Baladeh earthquake of M _w 6.2. The local recurrence time map before the earthquake shows anomalously short T _L in the epicentral region of the Baladeh earthquake a decade before its occurrence. The T _L map after the earthquake indicates that this large event has redistributed the applied stress in the Alborz region. The microseismicity of the region after the Baladeh earthquake, however, suggests that there are two anomalies in T _L map positioned in Alborz. The places where these anomalies are observed can be considered as the areas with maximum seismic hazard for future large earthquake in the Alborz region.     

Elasticity of aluminate,titanate, stannate and germanate compounds with the perovskite structure

Ultrasonic data for the velocities of a large number of perovskite-structure compounds have been determined as a a function of pressure to 6 kbar at room temperature for polycrystalline specimens hot-pressed at pressures up to 100 kbar in solid-media devices: ScAlO₃, GdAlO₃, SmAlO₃, EuAlO₃, YAlO₃, CdTiO₃, CdSnO₃, CaSnO₃ and CaGeO₃. The elasticity data for these orthorhombic and cubic perovskites define systematic patterns on bulk modulus (K_S)-volume (V_O) and bulk sound velocity (υ_φ—mean atomic weight (M) diagrams which are insensitiv to the details of cation chemistry and crystallographic structure. These isostructural trends are used to estimate K_S = 2.5 ± 0.3 Mbar and υ_φ = 7.9 ± 0.4 km/s for the perovskite polymorph of MgSiO₃. On a Birch diagram of veloc vs. density, the perovskite data define linear trends which lead to erroneous estimates of velocity for MgSiO₃ unless specific account is taken of ionic radius effects in isomorphic substitutions.