Using synchronous fluorescence spectroscopy and principal components analysis to monitor dissolved organic matter dynamics in a glacier system

The molecular characteristics of dissolved organic matter (DOM) reflect both its source material and its biogeochemical history. In glacial systems, DOM characteristics might be expected to change over the course of a melt season as changes in the glacier drainage system cause the mobilization of DOM from different OM pools. To test this hypothesis we used Principal Components Analysis (PCA) of synchronous fluorescence spectra to detect and describe changes in the DOM in meltwater from a glacier system in the Coast Mountains of northern British Columbia, Canada. For most of the melt season, the dominant component of subglacially routed meltwater DOM is characterized by a tyrosine‐like fluorophore. This DOM component is most likely derived from supraglacial snowmelt. During periods of high discharge, a second component of DOM is present which is humic in character and similar to DOM sampled from a nearby non‐glacial stream. This DOM component is inferred to be derived from a moss‐covered soil environment that has been glacially overrun. It is probably entrained into glacial melt waters when the supraglacial meltwater flux exceeds the capacity of the principal subglacial drainage channels and water floods areas of the glacier bed that are normally isolated from the subglacial drainage system. Another source of DOM also appears to be mobilized during periods of high air temperatures. It is characterized by both humic and proteinaceous fluorophores and may be derived from the drainage of supraglacial cryoconite holes. Copyright © 2009 John Wiley & Sons, Ltd.     

Laplace transform solutions for solute transport in fissured aquifers

The main processes affecting the migration of a solute in a fissured aquifer will be advection and dispersion in the fissures, diffusion into the porous matrix; and adsorption. This paper considers solute transport in an idealized fissured aquifer consisting of slabs of saturated rock-matrix separated by equally spaced, planar fissures. The solution of the transport equations is developed as far as Laplace transforms of the solute concentrations in the fissure and matrix water. Numerical inversion of the transforms is used to investigate characteristic behaviour of the model for a number of special cases.     

Martian atmospheric water vapor observations: 1972–1974 apparition

The patrol of Martian water vapor carried out with the echelle-coudé scanner at McDonald Observatory during the 1972–1974 apparition has produced 469 individual photoelectric scans of Doppler-shifted Martian H₂O lines. Almost an entire Martian year was covered during the 1972–1974 period (L_s = 118?269° and 301?80°). Three types of coverage have been obtained: (1) regular—the slit placed pole to pole on the central meridian; (2) latitudinal—the slit placed parallel to the Martian equator at various latitudes; (3) diurnal—the slit placed parallel to the terminator at several times during a Martian day measured from local noon.Both the seasonal and diurnal effects seem to be controlled by the insolation and not the local topography with respect to the 6.1 mb surface. A slight negative correlation with elevation was noted which improved during the seasons of greater H₂O content. The previous seasonal behavior has been confirmed and amplified. The following are the primary conclusions: (1) The planetwide abundance is low (5?15 μm of ppt H₂O) during both equinoctical periods. (2) The maximum abundance of about 40 μm occurs in each hemisphere after solstice at about 40° latitude in that hemisphere. (3) The latitude of the maximum amount in the N-S distribution precedes the latitude of maximum insolation by 10–20° of latitude. (4) During the “drier” seasons (5–20 μm) near the equinoxes on Mars, the atmospheric water vapor changes by a factor of 2–3x over a diurnal cycle with the maximum near local noon. (5) The effects of the 1973 dust storm during the southern summer reduced the amount of water vapor over the southern hemisphere regions to 3–8 μm.     

The QUESTRONIC PROJECT AND THE FERRANTI MRT 100 A BOON FOR SURVEY RESEARCH*

The overall aim of the Questronic project has been to focus upon techniques in data recording, data preparation and processing for computer input. The development and subsequent commercialization of these specific routines has come to fruition with the production of the Ferranti MRT 100. This initial product of the Questronic project has major ramifications for behavioral-survey investigations.     

Anaerobic oxidation of methane and sulfate reduction along the Chilean continental margin

Anaerobic oxidation of methane (AOM) and sulfate reduction (SR) were investigated in sediments of the Chilean upwelling region at three stations between 800 and 3000 m water depth. Major goals of this study were to quantify and evaluate rates of AOM and SR in a coastal marine upwelling system with high organic input, to analyze the impact of AOM on the methane budget, and to determine the contribution of AOM to SR within the sulfate-methane transition zone (SMT). Furthermore, we investigated the formation of authigenic carbonates correlated with AOM. We determined the vertical distribution of AOM and SR activity, methane, sulfate, sulfide, pH, total chlorins, and a variety of other geochemical parameters. Depth-integrated rates of AOM within the SMT were between 7 and 1124 mmol m⁻² a⁻¹, effectively removing methane below the sediment-water interface. Single measurements revealed AOM peaks of 2 to 51 nmol cm⁻³ d⁻¹, with highest rates at the shallowest station (800 m). The methane turnover was higher than in other diffusive systems of similar ocean depth. This higher turnover was most likely due to elevated organic matter input in this upwelling region offering significant amounts of substrates for methanogenesis. SR within the SMT was mostly fuelled by methane. AOM led to the formation of isotopically light DIC (δ¹³C: −24.6‰ VPDB) and of distinct layers of authigenic carbonates (δ¹³C: −14.6‰ VPDB).     

Application of Network-averaged Teleseismic P-wave Spectra to Seismic Yield Estimation of Underground Nuclear Explosions

—?A set of procedures is described for estimating network-averaged teleseismic P-wave spectra for underground nuclear explosions and for analytically inverting these spectra to obtain estimates of m _b /yield relations and individual yields for explosions at previously uncalibrated test sites. These procedures are then applied to the analyses of explosions at the former Soviet test sites at Shagan River, Degelen Mountain, Novaya Zemlya and Azgir, as well as at the French Sahara, U.S. Amchitka and Chinese Lop Nor test sites. It is demonstrated that the resulting seismic estimates of explosion yield and m _b /yield relations are remarkably consistent with a variety of other available information for a number of these test sites. These results lead us to conclude that the network-averaged teleseismic P-wave spectra provide considerably more diagnostic information regarding the explosion seismic source than do the corresponding narrowband magnitude measures such as m _b , M _s and m _b (L _g ), and, therefore, that they are to be preferred for applications to seismic yield estimation for explosions at previously uncalibrated test sites.     

Electrical Leak Detection System for Landfill Liners: A Case History

As landfill specifications become more stringent in the United Kingdom, the development of increasingly sophisticated monitoring methods is necessary to meet environmental protection goals. This case history describes the development of a 2-million-cubic-meter-capacity landfill located in a sandstone quarry and 1 km from a public water supply borehole, where the sensitivity of the site to ground water contamination and the proximity to a public water supply borehole are particular issues.
The landfill design incorporated a more sensitive environmental monitoring system, using a geophysical technique. The monitoring system comprises a permanent grid of electrodes installed beneath the landfill, connected by multicore cable to a computer-controlled earth resistance meter and switching unit in the site weighbridge. It was designed to detect holes in the landfill liner prior to and after covering with waste and to monitor the migration of contaminants beneath the landfill before they reach the perimeter observation boreholes, should leakage occur.
Such monitoring can enable the integrity of the landfill to be routinely reviewed; holes can be repaired if they are readily accessible and, if not, monitoring provides an early warning to enable the implementation of any additional monitoring or corrective action, based on the environmental risk posed by the site.
The system was first used as a quality assurance test once the landfill liner, which covered an area of 3 hectares, was installed. The system proved sensitive, detecting a hole consisting of two narrow knife cuts. Such sensitivity allows a high degree of confidence to be placed upon the integrity of the liner resulting in a significant contribution to public reassurance. The landfill is now operational, and monitoring using the geophysical system will be undertaken on a monthly basis for the first year, with the frequency of monitoring reviewed thereafter.