Adapting an Ecological Mangrove Model to Simulate Trajectories in Restoration Ecology

We used an ecological model to simulate the trajectories of mangrove attributes according to different restoration criteria at geographically specific conditions and at decadal time scales. This model can contribute to the design and implementation of restoration projects, and also be used to verify key mechanisms controlling ecosystem attributes during the recovery period. An existing gap model of mangrove wetlands, FORMAN, was used to simulate restoration trajectories in one of the largest estuary rehabilitation projects (128 000 ha) in South America, Ciénaga Grande de Santa Marta, Colombia (CGSM). Recovery of a disturbed mangrove forest based on simulations of basal area following reductions of salinity to 40 g/kg within 2 yr or 10 yr time periods suggests that in both cases dominance would reach about 75% of that in the reference site (80 m²/ha) in 40 yr. Both forests are >80% dominated by Avicennia, and Laguncularia has greater basal area than Rhizophora in the remaining structure. Simulations of forest recovery with a 25 yr target for salinity reduction show that only about 50% of the basal area in the reference site is recovered after 40 yr. After 40 yr of recovery, both the 2 and 10 yr salinity targets produce higher basal area and different patterns of community composition (Laguncularia becomes the dominant species) under enhanced recruitment (planting program) than observed under more natural recruitment. Ecological models can be used to establish trajectories of mangrove response to a variety of initial site conditions at spatially explicit locations that can improve engineering designs, project operation, and more clearly define monitoring programs and natural resource valuation. Modelling techniques can be used to identify the appropriate spatial and temporal scales of problems associated with mangrove restoration projects that could improve our ability to conserve and manage one of the most valuable forested wetlands in the tropical coastal zone.     

Forests and floods: Using field evidence to reconcile analysis methods

The extent to which forests, relative to shorter vegetation, mitigate flood peak discharges remains controversial and relatively poorly researched, with only a few significant field studies. Considering the effect purely of change of vegetation cover, peak flow magnitude comparisons for paired catchments have suggested that forests do not mitigate large floods, whereas flood frequency comparisons have shown that forests mitigate frequencies over all magnitudes of flood. This study investigates the apparent inconsistency using field-based evidence from four contrasting field programmes at scales of 0.34–3.1 km². Repeated patterns are identified that provide strong evidence of real effects with physical explanations. Magnitude and frequency comparisons are both relevant to the impact of forests on peak discharges but address different questions. Both can show a convergence of response between forested and grassland/logged states at the highest recorded flows but the associated return periods may be quite variable and are subject to estimation uncertainty. For low to moderate events, the forested catchments have a lower peak magnitude for a given frequency than the grassland/logged catchments. Depending on antecedent soil saturation, a given storm may nevertheless generate peak discharges of the same magnitude for both catchment states but these peaks will have different return periods. The effect purely of change in vegetation cover may be modified by additional forestry interventions, such as road networks and drainage ditches which, by effectively increasing the drainage density, may increase peak flows for all event magnitudes. For all the sites, forest cover substantially reduces annual runoff.     

Simple laminar dynamos: from two rolls to one

The study of laminar flows with simple streamlines in conducting fluids that might support kinematic dynamo action has a long history. Early successful examples include the Gailitis (1970 Gailitis, A. 1970. Self-excitation of a magnetic field by a pair of annular vortices. Mag. Gidrod, 6: 19–22. (English translation: Magnetohydrodynamics, 6:14–17) [Google Scholar]) dynamo, which has two meridional rolls. We show here that a single meridional roll, considered as a limit of a modified Gailitis-like dynamo, can also support kinematic dynamo action in a deep spherical shell. This flow has a claim to be the simplest such flow possible.     

Global Paleomagnetic Database Supplement number one: Update to 1992

This is the first Supplement to the Manual, first published inSurveys in Geophysics in 1991 and issued also as a separate volume, for the operation of the Global Paleomagnetic Database (GPMDB) using ORACL E. Minor changes have been made to the database structure as foreshadowed in the Manual and major extensions have been made to the MENU involving a new set of command files. These and other changes are detailed and should be read in conjunction with the original Manual. This latest Version 2.2 of the the GPMDB now contains over 7000 results with over 2600 references and covers all published data world-wide up to the end of 1992. Diskettes containing the new data set and accompanying program files may be obtained, as before, from World Data Center A in Boulder, Colorado. Both the updated data set and program files completely replace the original Version 1.4 released in August 1991.     

Nicholas Rast: A geologist who straddled the Atlantic but never an issue

Nicholas Rast died in Lexington, Kentucky on 28 August 2001, five months after his retirement as the first holder of the Hudnall Chair of Geology, Department of Geological Sciences, University of Kentucky. Born in Teheran in 1927, his early education was in Iran; his university education from 1948 was at University College London and University of Glasgow. His brilliant career as a university professor and award-winning researcher began in Aberystwyth, University of Wales, University of Liverpool, and continued in North America at the University of New Brunswick, Canada, and at the University of Kentucky, USA. Rast's published research consists of over 100 books and papers as well as abstracts in scientific journals. The abstracts represent topics which Nick Rast and his collaborators presented to participants at scientific meetings, symposia, and conferences; he was never one to let a good idea lie fallow, and I think it is accurate to say that every abstract evolved into a published paper. Wherever Nick worked he became deeply involved in influential activities of the geological societies of the country and in so doing left his imprint on the policies of these societies in England, Wales, Scotland, Ireland, Mexico, Canada and the United States. The organization of this retrospective deals generally with the chronology of Nick Rast's life and career. It includes a selection from among his most significant peer-cited reviewed publications, all of which are listed at the end of this chapter. From this list I have attempted to highlight some of the most important ideas contained in these publications. In addition I have interspersed a few colorful reminiscences by Nick's many friends, colleagues, and former students. These recalls were part of my “Rastfest” retirement banquet illustrated lecture which is now available on the Kentucky departmental website.     

单机地震数据采集系统NCDAS——华北地区遥测地震台网联网论文续一

设计了一套单机地震数据采集软件系统NCDAS.文中描述了该软件的总体结构、各任务块的功能、事件检测算法以及硬件环境.     

NMR Measurements in Carbonate Rocks: Problems and an Approach to a Solution

Carbonate rocks are well known for their complex petrophysical behavior where, in contrast to siliciclastic rocks, different parameters, including porosity and permeability, usually are not directly related. This behavior is the result of thorough reorganization of porosity during diagenesis, and it turns prediction of reservoir quality of carbonate rocks into a challenge. The study presented here deals with the problem of utilizing NMR techniques in prediction of petrophysical properties in carbonates.We employ a visual porosity classification as a priori knowledge for better interpreting NMR data for prediction purposes. This allows for choice of suitable T₂ cutoff values to differentiate movable from bound fluids adapted for the specific carbonate rock, thus resulting in better interpretation of NMR data. The approach of using a genetic pore type classification for adapting the conventional method for T₂ cutoff determination, which originally was developed for siliciclastic rocks, is promising. Similarly, for permeability determination on the basis of NMR measurements, the classification of carbonate rocks based on porosity types also shows potential. The approach implemented here has the promise to provide a basis of standardized interpretation of NMR data from carbonate rocks.Acknowledgment We are grateful to Baker Hughes INTEQ, Celle, for permission to publish the results of this work. This study was part of I.S.s Masters Thesis at Hannover University that was carried out in collaboration with Baker Hughes INTEQ, Celle, Germany. We appreciate comments of an anonymous referee and PAGEOPH editor Brian J. Mitchell.     

Causes of microgravity change at Poás volcano,Costa Rica: an active but non-erupting system

Microgravity changes with time, not always consistent with the Bouguer-corrected free air gradient, have been recorded and associated with cyles of eruptive activity at Krafla, Kilauea, Pacaya and Etna volcanoes. In contrast, over the non-erupting yet active fumarolic vents at Poás (Costa Rica), real-time gravity observations over three periods during the years 1983–1985 have identified ca. 140µGal amplitude, cyclic gravity variations. Their decrease in amplitude with distance from the active crater, coupled with a static sub-surface structural model, have allowed the effects of a variety of possible causative dynamic phenomena to be evaluated. It is concluded that cyclic changes in the average density (by ca. 0.03 Mg m^–3) in the magma pipe at depths below 500 m, rather than variation in magma chamber or water table geometry, are responsible for the observed gravity variations. Specifically, anaverage of 1 % fluctuation in the volume of gas in crystal-free magma, a process driven by thermal convection cycles, probably accounts for the density/gravity change.     

Risk measures for events with a stochastic duration: an application to drought analysis

Droughts, as many climatic and environmental phenomena, are events with a random duration. In the monitoring and risk management of this type of phenomena, it is important the development of measures of the risk that an ongoing event ends. This work develops a risk measure conditional on the current state of the event, that can be easily updated in real time. The measure is based on the hazard function of the duration of an event, that is modeled as a parametric function of covariates describing the current state of the process. The use of (time-dependent) internal covariates is often required to describe that state, and maximum likelihood methods cannot be used to estimate the model. Therefore, an approach based on partial likelihood functions that permit the inclusion of both external and internal covariates is suggested. This approach is very general but it has the drawback of requiring some programming to be implemented. However, it is proved that for durations with a geometric distribution, an equivalent and easily implemented approach based on generalized linear models can be used to estimate the hazard function. This methodology is applied to develop a risk measure in drought analysis. The approach is exemplified using the drought series from a Spanish location (Huesca) and internal covariates derived from the rainfall series. The whole modeling process is thoroughly described, including the covariate selection procedure and some new validation tools.     

Gladstone, Australia Field Studies: Weathering and Degradation of Hydrocarbons in Oiled Mangrove and Salt Marsh Sediments With and Without the Application of an Experimental Bioremediation Protocol

This field study was a combined chemical and biological investigation of the relative rates of weathering and biodegradation of oil spilled in sediments and testing the influence of a bioremediation protocol. The aim of the chemistry work presented here was to determine whether the bioremediation protocol affected the rate of penetration, dissipation or long-term retention of a medium range crude oil (Gippsland) and a Bunker C oil stranded in tropical Rhizophora sp. mangrove and Halosarcia sp. salt marsh environments. Permission for the planned oil spills was granted in the Port Authority area of Gladstone, Queensland (Australia). Sediment cores from three replicate plots of each treatment for mangroves and four replicate plots for the salt marsh (oil only and oil plus bioremediation) were analysed for total hydrocarbons (THC) and for individual alkane markers using gas chromatography with flame ionization detection (GC–FID). Sediments were collected at day 2, then 1, 2, 5 or 6 and 12 or 13 months post-spill for mangroves and day 2, 1, 3 and 9 months post-spill for salt marshes. Over this time, hydrocarbons in all of the oil treated plots decreased exponentially. There was no statistical difference in initial oil concentrations, penetration of oil to depth, or in the rates of oil dissipation between untreated oil and bioremediated oil in the mangrove plots. The salt marsh plots treated with the waxy Gippsland oil showed a faster rate of biodegradation of the oil in the bioremediated plots. In this case only, the degradation rate significantly impacted the mass balance of remaining oil. The Bunker C oil contained only minor amounts of highly degradable n-alkanes and bioremediation did not significantly impact its rate of loss in the salt marsh sediments. At the end of each experiment, there were still n-alkanes visible in the gas chromatograms of residual oils. Thus it was concluded that there was unlikely to be any change in the stable internal biomarkers of the oils over this time period. The predominant removal processes in both habitats were evaporation and dissolution, with a lag-phase of 1–2 months before the start of microbial degradation.     

“In-site” regionalization to estimate an intensity-duration-frequency law: a solution to scarce spatial data in Spain

The study of annual maximum rainfall intensity is quite difficult in Spain due to its limited recording rain gauges and short record lengths. This problem can't be solved applying classical regional approach, since scarce stations and great climate variability prevents forming homogeneous regions. The present study tries a new way of applying regionalization, a method which improves robustness, joining series with different durations (≤1 hour, > 1 hour) at the same station to form regions. Besides, the SQRT-ETmáx distribution is used due to extreme rainfall intensity in the Mediterranean area is not under Gumbel law domain. Copyright © 2007 John Wiley & Sons, Ltd.     

Lockdown as an Empirical Strategy to Curb Air Pollution: Evidence from a Quasi-Natural Experiment

In this study, three approaches namely parallel, sequential, and multiple linear regression are applied to analyze the local air quality improvements during the COVID-19 lockdowns. In the present work, the authors have analyzed the monitoring data of the following primary air pollutants: particulate matter (PM₁₀ and PM_2.5), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and carbon monoxide (CO). During the lockdown period, the first phase has most noticeable impact on airquality evidenced by the parallel approach, and it has reflected a significant reduction in concentration levels of PM₁₀ (27%), PM_2.5 (19%), NO₂ (74%), SO₂ (36%), and CO (47%), respectively. In the sequential approach, a reduction in pollution levels is also observed for different pollutants, however, these results are biased due to rainfall in that period. In the multiple linear regression approach, the concentrations of primary air pollutants are selected, and set as target variables to predict their expected values during the city's lockdown period.The obtained results suggest that if a 21-days lockdown is implemented, then a reduction of 42 µg m⁻³ in PM₁₀, 23 µg m⁻³ in PM_2.5, 14 µg m⁻³ in NO₂, 2 µg m⁻³ in SO₂, and 0.7 mg m⁻³ in CO can be achieved.