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Full-Text Articles in Life Sciences

Watershed Modeling And Sediment Yield Prediction Of The Los Olmos Creek Watershed In South Texas, Rockford Miller, Jungseok Ho, Chu-Lin Cheng Dec 2016

Watershed Modeling And Sediment Yield Prediction Of The Los Olmos Creek Watershed In South Texas, Rockford Miller, Jungseok Ho, Chu-Lin Cheng

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Studying the sediment that accumulates in a stream is an important aspect in the study of water quality and resources. With respect to water quality, the main issue is the turbidity of the water. Increased losses of natural landscape increase the erosion process in turn raising the turbidity of the water and reducing the light that can penetrate to the water reducing the growth of aquatic life. With respect to water resources, sediment accumulates in the river ways, harbors, and in dams reducing the effectiveness of these resources. This study focused on determining the amount of sediment that is outputted …


Adsorptive And Kinetic Characterization Of Aqueous Zinc Removal By Biochars, Sergio Mireles, Yongsik Ok, Chu-Lin Cheng, Jihoon Kang Nov 2016

Adsorptive And Kinetic Characterization Of Aqueous Zinc Removal By Biochars, Sergio Mireles, Yongsik Ok, Chu-Lin Cheng, Jihoon Kang

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Biochars have shown a great potential to treat stormwater runoff contaminated with heavy metals due to their favorable physical and chemical characteristics. Biochar materials were produced from pyrolysis of oak tree and wood at 400C and 450C respectively, and their Zn adsorption behavior from aqueous solutions were evaluated to assess their applicability as a filter media for stormwater treatment. Two adsorption isotherm models, Freundlich and Langmuir, were used to fit the batch-scale experimental data. The kinetics of Zn adsorption was investigated under two contrasting physical condition (stagnant vs. agitated). The adsorption isotherm was better fitted with the Langmuir model (R2 …


The Late Quaternary Rio Grande Delta—A Distinctive, Underappreciated Geologic System, Thomas E. Ewing, Juan L. Gonzalez Sep 2016

The Late Quaternary Rio Grande Delta—A Distinctive, Underappreciated Geologic System, Thomas E. Ewing, Juan L. Gonzalez

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

The delta of the Rio Grande/Rio Bravo in southernmost Texas and northern Tamaulipas is one of the major deltas of North America. Over 600,000 people live on the Holocene delta and river plain, and a million more on its Pleistocene ancestors, yet geo-logic knowledge is limited. Combining available geologic information with global satellite photography gives a balanced view of an important delta. The Holocene delta begins at a point west of San Benito, Texas, forming a classic eastward-opening delta. Over half of the delta lies south of the present Rio Grande drainage. The delta passes westward into a floodplain that …


Assessment Of Indoor And Outdoor Pm Species At Schools And Residences In A High-Altitude Ecuadorian Urban Center, Amit U. Raysoni, Rodrigo X. Armijos, M. Margaret Weigel, Teresa Montoya, Patricia Eschanique, Marcia Racines, Wen-Whai Li Jul 2016

Assessment Of Indoor And Outdoor Pm Species At Schools And Residences In A High-Altitude Ecuadorian Urban Center, Amit U. Raysoni, Rodrigo X. Armijos, M. Margaret Weigel, Teresa Montoya, Patricia Eschanique, Marcia Racines, Wen-Whai Li

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

An air monitoring campaign to assess children’s environmental exposures in schools and residences, both indoors and outdoors, was conducted in 2010 in three low-income neighborhoods in Z1(north), Z2(central), and Z3(southeast) zones of Quito, Ecuador - a major urban center of 2.2 million inhabitants situated 2850 meters above sea level in a narrow mountainous basin. Z1 zone, located in northern Quito, historically experienced emissions from quarries and moderate traffic. Z2 zone was influenced by heavy traffic in contrast to Z3 zone which experienced low traffic densities. Weekly averages of PM samples were collected at schools (one in each zone) and residences …


Do Some Deep‐Sea, Sediment‐Dwelling Species Of Harpacticoid Copepods Have 1000‐Km‐Scale Range Sizes?, Erin E. Easton, David Thistle Jun 2016

Do Some Deep‐Sea, Sediment‐Dwelling Species Of Harpacticoid Copepods Have 1000‐Km‐Scale Range Sizes?, Erin E. Easton, David Thistle

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

The range sizes of sediment‐dwelling deep‐sea species are largely unknown. Such knowledge is important because a deep sea composed in large part of species with 100‐km‐scale ranges would be very different from one composed predominantly of species with 1000‐km‐scale ranges. For example, the total species richness would be much greater in the first case than in the second. As a step towards the determination of the distribution of species’ range sizes in the deep sea, we asked whether harpacticoid copepods (Crustacea) on the continental rise in the northeastern Pacific had 1000‐km‐scale range sizes. We chose harpacticoids because they occur widely …


Potential And Timescales For Oxygen Depletion In Coastal Upwelling Systems: A Box-Model Analysis, Cheryl S. Harrison, B. Hales, S. Siedlecki, R. M. Samelson May 2016

Potential And Timescales For Oxygen Depletion In Coastal Upwelling Systems: A Box-Model Analysis, Cheryl S. Harrison, B. Hales, S. Siedlecki, R. M. Samelson

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

A simple box model is used to examine oxygen depletion in an idealized ocean-margin upwelling system. Near-bottom oxygen depletion is controlled by a competition between flushing with oxygenated offshore source waters and respiration of particulate organic matter produced near the surface and retained near the bottom. Upwelling-supplied nutrients are consumed in the surface box, and some surface particles sink to the bottom where they respire, consuming oxygen. Steady states characterize the potential for hypoxic near-bottom oxygen depletion; this potential is greatest for faster sinking rates, and largely independent of production timescales except in that faster production allows faster sinking. Timescales …


Comparative Analysis Of Xenorhabdus Koppenhoeferi Gene Expression During Symbiotic Persistence In The Host Nematode, Ruisheng An, Parwinder Grewal Jan 2016

Comparative Analysis Of Xenorhabdus Koppenhoeferi Gene Expression During Symbiotic Persistence In The Host Nematode, Ruisheng An, Parwinder Grewal

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Species of Xenorhabdus and Photorhabdus bacteria form mutualistic associations with Steinernema and Heterorhabditis nematodes, respectively and serve as model systems for studying microbe-animal symbioses. Here, we profiled gene expression of Xenorhabdus koppenhoeferi during their symbiotic persistence in the newly formed infective juveniles of the host nematode Steinernema scarabaei through the selective capture of transcribed sequences (SCOTS). The obtained gene expression profile was then compared with other nematode-bacteria partnerships represented by Steinernema carpocapsae-Xenorhabdus nematophila and Heterorhabditis bacteriophora-Photorhabdus temperata. A total of 29 distinct genes were identified to be up-regulated and 53 were down-regulated in X. koppenhoeferi while in S. scarabaei infective …


Beyond Just Sea-Level Rise: Considering Macroclimatic Drivers Within Coastal Wetland Vulnerability Assessments To Climate Change, Michael J. Osland, Nicholas M. Enwright, Richard H. Day, Christopher A. Gabler, Camille L. Stagg, James B. Grace Jan 2016

Beyond Just Sea-Level Rise: Considering Macroclimatic Drivers Within Coastal Wetland Vulnerability Assessments To Climate Change, Michael J. Osland, Nicholas M. Enwright, Richard H. Day, Christopher A. Gabler, Camille L. Stagg, James B. Grace

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

Due to their position at the land-sea interface, coastal wetlands are vulnerable to many aspects of climate change. However, climate change vulnerability assessments for coastal wetlands generally focus solely on sea-level rise without considering the effects of other facets of climate change. Across the globe and in all ecosystems, macroclimatic drivers (e.g., temperature and rainfall regimes) greatly influence ecosystem structure and function. Macroclimatic drivers have been the focus of climate change-related threat evaluations for terrestrial ecosystems, but largely ignored for coastal wetlands. In some coastal wetlands, changing macroclimatic conditions are expected to result in foundation plant species replacement, which would …