Earth Sciences Commons^™

Letter To The Editor Regarding, “First Evidence On Different Transportation Modes Of Arsenic And Phosphorus In Arsenic Hyperaccumulator Pteris Vittata” By Lei Et Al. (2012), Nabeel Niazi, Anthony Kachenko

Dr Nabeel Khan Niazi

No abstract provided.

Mechanisms Of Metal-Phosphates Formation In The Rhizosphere Soils Of Pea And Tomato: Environmental And Sanitary Consequences, Annabelle Austruy, Muhammad Shahid, Tiantian Xiong, Maryse Castrec, Virginie Payre, Nabeel Niazi, Muhammad Sabir, Camille Dumat

Dr Nabeel Khan Niazi

Purpose: At the global scale, soil contamination with persistent metals such as lead (Pb), zinc (Zn), and copper (Cu) induces a serious threat of entering the human food chain. In the recent past, different natural and synthetic compounds have been used to immobilize metals in soil environments. However, the mechanisms involved in amendment-induced immobilization of metals in soil remained unclear. The objective of the present work was therefore to determine the mechanisms involved in metal-phosphates formation in the rhizospheric soils of pea and tomato currently cultivated in kitchen gardens. Materials and methods: Pea and tomato were cultivated on a soil …

Mid-Infrared Spectroscopy And Partial Least-Squares Regression To Estimate Soil Arsenic At A Highly Variable Arsenic-Contaminated Site, Nabeel Niazi, Balwant Singh, B Minasny

Dr Nabeel Khan Niazi

The potential of mid-infrared spectroscopy in combination with partial least-squares regression was investigated to estimate total and phosphate-extractable arsenic contents in soil samples collected from a highly variable arsenic-contaminated disused cattle-dip site. Principal component analysis was performed prior to mid-infrared partial least-squares analysis to identify spectral outliers in the absorbance spectra of soil samples. The mid-infrared partial least-squares calibration model (n = 149) excluding spectral outliers showed an acceptable reliability (coefficient of determination, R2c = 0.75 (P < 0.01); ratio of performance to interquartile distance, RPIQ_c = 2.20) to estimate total soil arsenic. For total soil arsenic, the validation of final calibration model using 149 unknown …

Arsenic Speciation And Phytoavailability In Contaminated Soils Using A Sequential Extraction Procedure And Xanes Spectroscopy, Nabeel Niazi, Balwant Singh, Pushan Shah

Dr Nabeel Khan Niazi

In this study, a sequential extraction procedure (SEP) and X-ray absorption near edge structure (XANES) spectroscopy were used to determine the solid-phase speciation and phytoavailability of arsenic (As) of historically contaminated soils from As containing pesticides and herbicides and soils spiked with As in the laboratory. Brassica juncea was grown in the contaminated soils to measure plant available As in a glasshouse experiment. Arsenic associated with amorphous Fe oxides was found to be the dominant phase using both SEP and XANES spectroscopy. Arsenic predominantly existed in arsenate (As V) form in the soils; in a few samples As was also …

Phytoremediation Potential Of Pityrogramma Calomelanos Var. Austroamericana And Pterris Vittata L. Grown At A Highly Variable Arsenic Contaminated Site, Nabeel Niazi, Balwant Singh, Lukas Van Zwieten, Anthony Kachenko

Dr Nabeel Khan Niazi

In this study, the phytoextraction potential of Pityrogramma calomelanos var. austroamericana (gold dust fern) was compared with the well-known arsenic (As) hyperaccumulator, Pteris vittata L. (Chinese brake fern) at a disused cattle dip site in northern New South Wales, Australia. Geostatistical analysis showed that the concentrations of total (at 0–20 cm depth) and phosphate-extractable (at 0–20, 20–40 and 40–60 cm depths) As were spatially variable at the site and this extreme variability (< 1 m) was also evident in the spatial maps of As. Gold dust fern produced greater frond dry biomass (mean=130 g/plant; n=40) than Chinese brake fern (mean=81 …

Phytoremediation Of An Arsenic-Contaminated Site Using Pteris Vittata L. And Pityrogramma Calomelanos Var. Austroamericana: A Long-Term Study, Nabeel Niazi, B Singh, L Van Zwieten, A Kachenko

Dr Nabeel Khan Niazi

This field study investigated the phytoremediation potential of two arsenic (As) hyperaccumulating fern species, Pityrogramma calomelanos var. austroamericana and Pteris vittata over 27-month duration at a disused As-contaminated cattle-dip site located at Wollongbar, NSW, Australia. Ferns planted in January 2009 were harvested following 10, 22 and 27 months of growth. A detailed soil sampling was undertaken in June 2009 (initial, n = 42 per plot) and limited sampling in April 2011 (after 27 months, n  = 15 per plot) to measure total and phosphate-extractable As concentrations in soil at 0 − 20-, 20 − 40- and 40 − 60-cm depths. …

Phytoremediation Potential Of Pityrogramma Calomelanos Var. Austroamericana And Pteris Vittata L. Grown At A Highly Variable Arsenic Contaminated Site, Nabeel Niazi, Balwant Singh, Lukas Van Zwieten, Anthony Kachenko

Dr Nabeel Khan Niazi

This study examined the phytoextraction potential of two arsenic (As) hyperaccumulators, Pteris vittata L. and Pityrogramma calomelanos var. austroamericana at a historical As-contaminated cattle dip site in northern New South Wales (NSW), Australia. Total As concentration in the surface soil (0–20 cm) showed a better spatial structure than phosphate-extractable As in the surface and sub-surface soil at this site. P. calomelanos var. austroamericana produced greater frond dry biomass (mean = 130 g plant−1) than P. vittata (mean = 81 g plant−1) after 10 months of growth. Arsenic concentration and uptake in fronds were also significantly higher in P. calomelanos var. …

The Extended Tracking Network And Indications Of Baseline Precision And Accuracy In The North Andes, Jeffrey Freymueller, James Kellogg

James N Kellogg

The CASA UNO Global Positioning System (GPS) experiment (January-February 1988) included an extended tracking network which covered three continents in addition to the network of scientific interest in Central and South America. The repeatability of long baselines (400-1000 km) in South America is improved by up to a factor of two in the horizontal vector baseline components by using tracking stations in the Pacific and Europe to supplement stations in North America. In every case but one, the differences between the mean solutions obtained using different tracking networks was equal to or smaller than day-to-day rms repeatabilities for the same …

Reply To Comment On "Subduction Of The Caribbean Plate And Basement Uplifts In The Overriding South American Plate", James Kellogg, William Bonini

James N Kellogg

No abstract provided.

Central And South America Gps Geodesy- Casa Uno, James Kellogg, Timothy Dixon

James N Kellogg

In January 1988, scientists from over 25 organizations in 13 countries and territories cooperated in the largest Global Positioning System (GPS) campaign in the world to date (Table 1). 43 GPS receivers collected approximately 590 station-days of data in America, Samoa, Australia, Canada, Colombia, Costa Rica, Ecuador, New Zealand, Norway, Panama, Sweden, United States, West Germany, and Venezuela. The experiment was entitled CASA UNO, an acronym for Central and South America -- and uno is the Spanish word for one, designating first epoch measurements. The CASA UNO experiment was the first civilian effort implementing a global GPS satellite tracking network. …

A 3-D Gravity Tectonic Study Of Ita Mai Tai Guyot: An Uncompensated Seamount In The East Mariana Basin, Bruce Wedgeworth, James Kellogg

James N Kellogg

Ita Mai Tai is a large, locally uncompensated seamount on the eastern edge of the East Mariana Basin. A large positive gravity anomaly of 254 mgal characterizes the summit and a low of -69 mgal, the surrounding moat. Using polygonal prisms to approximate the bathymetry, the observed gravity was inverted to calculate an average density of 2.59 g/ems for the seamount. Observed-calculated gravity residuals are reduced by including the flanking sedimentary basins and a dense volcanic conduit. The drill sites from DSDP Legs 20 and 89 describe a volcanic edifice formed in the Aptian!Albian on Jmassic/Cretaceous crust. The volcanism is …

Seismic Evidence For Blind Thrusting Of The Northwestern Flank Of The Venezuelan Andes, Bruno De Toni, James Kellogg

James N Kellogg

Surface geology and seismic and well data from the northwestern flank of the Venezuelan Andes indicate overthrusting of Andean basement rocks toward the adjacent Maracaibo Basin along a blind thrust fault. The frontal monocline is interpreted as the forelimb of a northwestward verging fault-related fold deformed over a crustal-scarle map. The Andean block has been thrust 20 km to the northwest and uplifted 10 km on a ramp that dips about 20o-30o southeastward. The thrust fault ramps up through crystalline basement rocks to a decollement horizon within the shaly units of the Cretaceous Colon-Mito Juan formations. Backthrusts in the monocline …

First Gps Baseline Results From The North Andes, James Kellogg, Jeffrey Freymueller, Timothy Dixon, Ruth Neilan, Clemente Ropain U., Sergio Camargo M., Benjamin Fernandez Ch., James Stowell, Anibal Salazar, Jaime Mora V., Luis Espin, Vernon Perdue, Leonard Leos

James N Kellogg

The CASA UNO GPS (Global Positioning System) experiment (January-February 1988) has provided the first epoch baseline measurements for the study of plate motions and crustal deformation in and around the North Andes. Two dimensional horizontal baseline repeatabilities are as good as 5 parts in 10⁸ for short baselines (100-1000km), and better than3 parts in 10⁸ for long baselines (>1000km). Vertical repeatabilities are typically 4 -6 cm, with a weak dependence on baseline length. The expected rate of plate convergence across the Colombia Trench is 6-8 cm/yr, which should be detectable by the repeat experiment planned for 1991. …

Isostatic Compensation And Conduit Structures Of Western Pacific Seamounts: Results Of Three-Dimensional Gravity Modeling, James Kellogg, Bruce Wedgeworth, Jeffrey Freymueller

James N Kellogg

Detailed three-dimensional polygonal prism models of two large western Pacific seamounts show that the 135 mgal difference in the observed sea surface gravity over the two can be best explained by similar mean densities (2.6 gjcm3) and crustal thickening under one seamount (Airy isostatic compensation). Observed calculated residuals are further reduced by including dense (2.9 gjcm3) vertical feeder pipes or volcanic conduits in the models. Dense conduits or fracture zones 5 to 17 km in diameter are located under many, if not all, craters on volcanic islands and seamounts. Results from the detailed seamount studies can be generalized using exact …

New Standards For Reducing Gravity Data: The North American Gravity Database, William Hinze, Carlos Aiken, John Brozena, Bernard Coakley, David Dater, Guy Flanagan, Rene Forsberg, Thomas Hildenbrand, G. Keller, James Kellogg, Robert Kucks, Xiong Li, Andre Mainville, Robert Morin, Mark Pilkington, Donald Plouff, Dhananjay Ravat, Daniel Roman, Jamie Urrutia-Fucugauchi, Marc Veronneau, Michael Webring, Daniel Winester

James N Kellogg

The North American gravity database as well as databases from Canada, Mexico, and the United States are being revised to improve their coverage, versatility, and accuracy. An important part of this effort is revising procedures for calculating gravity anomalies, taking into account our enhanced computational power, improved terrain databases and datums, and increased interest in more accurately defining long-wavelength anomaly components. Users of the databases may note minor differences between previous and revised database values as a result of these procedures. Generally, the differences do not impact the interpretation of local anomalies but do improve regional anomaly studies. The most …

Field Validation Of Dem And Gis Derived Longitudinal Stream Profiles, Kathryn Schroeder, Eric Peterson, Toby Dogwiler

Eric Wade Peterson

Longitudinal stream profiles provide valuable information concerning geomorphic features and energy states in a stream. Traditionally, stream profiles have been generated by field surveying or topographic map analysis. The continued growth of digital data and Geographic Information Systems (GISs) provide another method by which to achieve stream profile generation. This work examines the effectiveness of digital data, digital elevation models (DEM), and GIS to construct stream profiles. To determine the most effective and accurate data for profile generation, profiles were created using 1-meter (1-m) and 3-meter (3-m) DEMs developed from LiDAR data. Additionally, stream profiles were created from unfilled DEMs …

Longitudinal Profile And Sediment Mobility As Geomorphic Tools To Interpret The History Of A Fluviokarst Stream System, John Woodside, Eric Peterson, Toby Dogwiler

Eric Wade Peterson

The complex drainage systems within karst settings can result in atypical longitudinal profiles. Features, such as cave entrances, can be expressed as anomalous ‘bumps’ in the longitudinal profile of a stream if downcutting has continued upstream of the area in which the water is pirated to the subsurface. Horn Hollow, a fluviokarst valley located in Carter Caves State Park Resort in northeastern Kentucky, was examined for these types of features. The objectives of this study were to determine if sediment mobility can be used as a proxy for anomalous areas along the profile of the valley and if detailed cross-sections …

Stratigraphy And Porosity Modeling Of Southern Centeral Illinois Chester (Upper Missisippian) Series Sandstones Usng Petrel, Darren Kimple, Eric Peterson, David Malone

Eric Wade Peterson

Identification Of Potential Vertical Gas Migration Pathways Above Gas Storage Reservoirs, Eric Peterson, Lauren Martin, David Malone

Eric Wade Peterson