Assessing the Comparability of Ammonium,Nitrate and Sulfate Concentrations Measured by Three Air Quality Monitoring Networks

Airborne fine particulate matter across the United States is monitored by different networks, the three prevalent ones presently being the Clean Air Status and Trend Network (CASTNet), the Interagency Monitoring of PROtected Visual Environment Network (IMPROVE) and the Speciation and Trend Network (STN). If combined, these three networks provide speciated fine particulate data at several hundred locations throughout the United States. Yet, differences in sampling protocols and samples handling may not allow their joint use. With these concerns in mind, the objective of this study is to assess the spatial and temporal comparability of the sulfate, nitrate and ammonium concentrations reported by each of these networks. One of the major differences between networks is the sampling frequency they adopted. While CASTNet measures pollution levels on seven-day integrated samples, STN and IMPROVE data pertain to 24-hour samples collected every three days. STN and IMPROVE data therefore exhibit considerably more short-term variability than their CASTNet counterpart. We show that, despite their apparent incongruity, averaging the data with a window size of four to six weeks is sufficient to remove the effects of differences in sampling frequency and duration and allow meaningful comparison of the signals reported by the three networks of concern. After averaging, all the sulfate and, to a lesser degree, ammonium concentrations reported are fairly similar. Nitrate concentrations, on the other hand, are still divergent. We speculate that this divergence originates from the different types of filters used to collect particulate nitrate. Finally, using a rotated principal component technique (RPCA), we determined the number and the geographical organization of the significant temporal modes of variation (clusters) detected by each network for the three pollutants of interest. For sulfate and ammonium, the clusters’ geographical boundaries established for each network and the modes of variations within each cluster seem to correspond. RPCA erformed on nitrate concentrations revealed that, for the CASTNet and IMPROVE networks, the modes of variation do not correspond to unified geographical regions but are found more sporadically. For STN, the clustered areas are unified and easily delineable. We conclude that the possibility of jointly using the data collected by CASTNet, IMPROVE and STN has to be weighed pollutant by pollutant. While sulfate and ammonium data show some potential for joint use, at this point, combining the nitrate data from these monitoring networks may not be a judicious choice.     

Magnetosheath Interaction with the High Latitude Magnetopause

We present both statistical and case studies of magnetosheath interaction with the high-latitude magnetopause on the basis of Interball-1 and other ISTP spacecraft data. We discuss those data along with recently published results on the topology of cusp-magnetosheath transition and the roles of nonlinear disturbances in mass and energy transfer across the high-latitude magnetopause. For sunward dipole tilts, a cusp throat is magnetically open for direct interaction with the incident flow that results in the creation of a turbulent boundary layer (TBL) over an indented magnetopause and downstream of the cusp. For antisunward tilts, the cusp throat is closed by a smooth magnetopause; demagnetized ‘plasma balls’ (with scale ∼ few R_E, an occurrence rate of ∼25% and trapped energetic particles) present a major magnetosheath plasma channel just inside the cusp. The flow interacts with the ‘plasma balls’ via reflected waves, which trigger a chaotization of up to 40% of the upstream kinetic energy. These waves propagate upstream of the TBL and initiate amplification of the existing magnetosheath waves and their cascade-like decays during downstream passage throughout the TBL. The most striking feature of the nonlinear interaction is the appearance of magnetosonic jets, accelerated up to an Alfvenic Mach number of 3. The characteristic impulsive local momentum loss is followed by decelerated Alfvenic flows and modulated by the TBL waves; momentum balance is conserved only on time scales of the Alfvenic flows (1/f_A ∼12 min). Wave trains at f_A∼1.3 mHz are capable of synchronizing interactions throughout the outer and inner boundary layers. The sonic/Alfvenic flows, bounded by current sheets, control the TBL spectral shape and result in non-Gaussian statistical characteristics of the disturbances, indicating the fluctuation intermittency. We suggest that the multi-scale TBL processes play at least a comparable role to that of macro-reconnection (remote from or in the cusp) in solar wind energy transformation and population of the magnetosphere by the magnetosheath plasma. Secondary micro-reconnection constitutes a necessary chain at the small-scale (∼ion gyroradius) edge of the TBL cascades. The thick TBL transforms the flow energy, including deceleration and heating of the flow in the open throat, ‘plasma ball’ and the region downstream of the cusp.     

Analysis of Many-Year Variations in River Runoff into the Arctic Ocean

Statistical analysis of long-term hydrological observations has shown that the interannual variations in the total river runoff into the Arctic Ocean can be considered as a stationary process. Similar are the variations in the annual runoff of the Ob, Lena, and rivers of the northwestern Asia. However, some components of the total runoff into the Arctic Ocean feature distinct and fairly complicated disturbances in the homogeneity of runoff variations. For example, variations in the annual runoff of the Yenisei River have a distinct nonmonotonic trend: the runoff systematically decreased till the late 1950s and increased since the late 1960s. The rivers of the European part of the Arctic Ocean drainage basin featured a decrease in the amplitude of variations in runoff during the past decades. Rivers of the northwestern America and northeastern Asia featured a regular increase in the amplitude of runoff variations and their autocorrelation since the late 1960s.     

Observed Evolution of Linear and Nonlinear Effects at the Dahan Downhole Array,Taiwan: Analysis of the September 21, 1999 M 7.3 Chi-Chi Earthquake Sequence

— In this paper, the site characteristics of the Dahan downhole array are studied by analyzing the September 21, 1999 M 7.3 Chi-Chi earthquake sequence including the main shock and some aftershocks. The four-level array (0 m, 50 m, 100 m and 200 m) is located to the north of Hualien City in eastern Taiwan. Polarization analysis is used to check the orientation errors of the seismometers at different levels of depth. If the surface instrument is chosen as reference, the angle between the major polarization axes of the surface and any downhole records is the orientation error that must be corrected for the downhole accelerographs. The orientation errors at depths of 50 m, 100 m and 200 m are 32°, 120° and –84°. After the corrections, the coherency between the surface and downhole records is substantially improved. Spectral ratio analysis shows that the predominant frequency of the Chi-Chi main shock shifts to a lower frequency. We also simulate ground motions at different depths by using the Haskell method with a linear velocity structure model. The record at surface is chosen as the input motion. Compared with the observed data, ground acceleration can be well reproduced for the aftershocks (weak-motion events) of the September 21, 1999 M 7.3 Chi-Chi earthquake. However, for the Chi-Chi main shock, the synthetic waveform cannot match well with the observation neither in amplitude nor in phase. This indicates that large ground shaking probably induced the nonlinear site effect at that time, and the model used cannot support it.Acknowledgement. The authors would like to express their thanks to Dr. L.F. Bonilla and one anonymous reviewer for their valuable suggestions. This research was supported by the National Science Council under grant number NSC 89-2921-M-194-007. The Institute of Earth Sciences, Academia Sinica supplied the strong-motion data. The support of these organizations is gratefully acknowledged.     

A Nonlinear Model of Contaminant Transformations in an Aquatic Environment

A nonlinear model of the decomposition of a multicomponent contaminant is developed with allowance made for the distribution of components over their reactivity. Model application is illustrated by the analysis of published empirical data on organic matter biodegradation in water column and bottom sediments, in an activated-sludge bioreactor, and the biological absorption and enzymatic destruction of organic matter by macrophytes. Photodestruction, chemical destruction, and sedimentation are also considered. The nonlinear model is compared with a first-order reaction equation.__________Translated from Vodnye Resursy, Vol. 32, No. 3, 2005, pp. 322–336.Original Russian Text Copyright © 2005 by Dolgonosov, Gubernatorova.     

Freshwater Deficiency and the World Market

The causes of freshwater deficiency are considered, the main causes being poor environmental conditions and excessive water consumption. The problem of water deficiency is shown to be insoluble without the development of intense water use, conservation, and protection. Based on studying water as a commodity, it is asserted that the market mechanism is not sufficient to cope with water deficiency. The potential of the international water market is shown to be very limited in contrast to the market of water-efficient processes and water-retaining products.     

Energetic Particles Observed in the CUSP Region During a Storm Recovery Phase

In this paper we report energetic ion behavior and its composition variations observed by the Cluster/RAPID instrument when the spacecraft was travelling in the high latitude magnetospheric boundary region on the day of the 31 March, 2001, strongest magnetic storm in the past 50 years. The Dst index reached −360 nT at about 09:00 UT. During its early recovery phase, large amounts of oxygen and helium ions were observed; the ratio of oxygen to hydrogen in the RAPID energy range reached as high as 250%, which suggests that the observed energetic particles might be of magnetospheric origin. The observations further show that enhanced energetic electron fluxes are confined in a very narrow region, while protons have occupied a larger region, and heavy ions have been observed in an even larger region. The flux of energetic electrons show a slight enhancement in a region where the magnetic field magnitude is around zero. These observed energetic ions could be quasi-trapped by the current sheet in the stagnation region of the cusp.     

Ecotoxicological Assessment of After-Effects of the Volga River Water Contamination

Comprehensive assessment of ecotoxicological situation in the Volga River basin is presented. Concentrations of organic and inorganic toxic substances are cited. Basic clinic and postmortem symptoms of intoxication in fish are described; changes in the cellular structure of their organs and tissues, as well as disturbances in hemogenesis, developing under the effect of toxic agents, are characterized. Based on the dose-effect dependences, calculated according to the values of the total concentration of toxic substances, standardized to MPC, and criteria of the physiological state of fish, cases of exceedance of the critical concentrations of pollutants are demonstrated for the investigated river sections.__________Translated from Vodnye Resursy, Vol. 32, No. 4, 2005, pp. 410–424.Original Russian Text Copyright © 2005 by Moiseenko, Gashkina, Sharova, Pokoeva.     

First estimate for the age of a mesoproterozoic palaeomagnetic pole from the Volodarsk-Volynsky Massif,the Ukrainian Shield

Palaeomagnetic data are presented from the southern Volodarsk-Volynsky Massif (VVM) of the Korosten Pluton, the Ukrainian Shield. Laboratory experiments (AF and thermal demagnetization, IRM acquisition, thermal separation), field tests (consistency and secular variation methods) and optical observations indicate that single domain and nearly single domain magnetite is the dominant carrier of a primary TRM in the anorthosites. Palaeomagnetic poles from the three sampling sites (Golovino and Turchinka quarries) are indistinguishable at the 95% confidence level and have been combined to yield a mean pole at P_lat = 30 °N, P_lon = 178 °E, a₉₅ = 3.4 °.In the large slow cooling Korosten Pluton the U-Pb zircon/baddeleyite (U_zb) technique gives an age for the anorthosites, which are not equivalent to the time of magnetic blocking. Based on integrated analysis of geochronologic information and blocking-temperature data for magnetic minerals proposed by Briden et al. (1993), a first attempt has been undertaken to estimate the palaeomagnetic pole age from the Mesoproterozoic anorthosites. The Korosten Pluton has cooled from 850 °C (the closure temperature of U-Pb systematics in zircon/baddeleyite) to 350 °C (the closure temperature of K-Ar systematics in biotite) during 150 Ma after the emplacement of the anorthosites. Assuming a uniform cooling of the intrusion yields a rate of 3.3 °C/Ma. The cooling rate for the granites is 3.1 °C/Ma. The mafic and acid rocks have an average rate of 3.2 °C/Ma. Using the cooling gradient for the VVM (3.2 °C/Ma) and the mean natural blocking temperature of magnetite (520 °C) can be determined a remanence age. The estimate for TRM acquisition is 1656 ± 10.0 Ma.The magnetic pole for the VVM is in good agreement with the mean pole from the Baltic quartz porphyry dykes with an age of 1630 – 1648 Ma. The VVM pole is best dated and requires a revision of the latest paleogeographic reconstructions for the Fennoscandian and Ukrainian Shields at 1770 and 1650 Ma. (Pesonen et al., 2003).     

Seasonal variations in thermo-, halo-, and pycnocline in the northeastern part of the Black sea (Based on long-term data)

Seasonal evolution of the vertical thermal, halininc, and density structure of water in the phases of warming and heat loss is shown. The annual cycle of variability of seasonal and deep-water thermo-, halo-, and pycnocline is discussed. It is revealed that variations in the seasonal (subsurface) thermo-, halo-, and pycnocline depend on the surface environmental factors (air temperature, river runoff, and precipitation), while variations in the deep-water thermo-, halo-, and pycnocline depend on the dynamic factor impact (seasonal variations in the intensity of the general cyclonic circulation in the Black Sea).Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 28–34.Original Russian Text Copyright © 2005 by Titov.