Biogeochemistry Commons^™

Magnetite Magnetosome Biomineralization In Magnetospirillum Magneticum Strain Amb-1: A Time Course Study, Lucas Le Nagard, Xiaohui Zhu, Hao Yuan, Karim Benzerara, Dennis A. Bazylinski, Cécile Fradin, Adrien Besson, Sufal Swaraj, Stefan Stanescu, Rachid Belkhou, Adam P. Hitchcock

Life Sciences Faculty Research

Magnetotactic bacteria are a highly studied group of diverse prokaryotes that biomineralize chains of magnetosomes, single domain, single crystal magnetic nanoparticles of magnetite or greigite, enclosed by a lipid bilayer membrane whose synthesis is under strict genetic control.

Natural And Constructed Wetlands For Ecosystem And Engineering Services In The Arid And Semi-Arid Regions, Achyut Raj Adhikari

UNLV Theses, Dissertations, Professional Papers, and Capstones

The Las Vegas Wash (LVW) has undergone significant wetlands degradation and soil erosion over the past thirty years due to increasing flow resulting from urbanization and large rainfall events in the Las Vegas Valley Watershed. The increased flow and associated pollution load in the LVW and its adverse impact in Lake Mead have alerted stakeholders to pay a greater attention to explore alternative measures for rehabilitation of wetland ecosystems. This dissertation, using the case of changes in LVW, analyzes and describes ecological and engineering services provided by wetlands in arid and semi-arid regions and provides a knowledge base that can …

Biological Effects On Serpentinite Weathering, Mary H. Evert, Julie Baumeister, Elisabeth Hausrath

Undergraduate Research Opportunities Program (UROP)

Serpentinites, perhaps more than any other rock type, control the composition and evolution of the development of the surrounding ecosystems. The bulk chemistry of serpentinite rocks, high in Mg and trace elements, and low in nutrients such as Ca, K, P, and N, causes an extreme and stressful environment for ecosystems. However, the role that those serpentine ecosystems play in development of serpentine soils has not been examined.

Due to the unusual chemistry of serpentine soils, serpentine ecosystems have deeper and better-developed root systems than other ecosystems. The rhizosphere of serpentine systems, documented to produce abundant organic acids and siderophores, …

Carbon Isotopic Fractionation Across A Late Cambrian Carbonate Platform: A Regional Response To The Spice Event As Recorded In The Great Basin, Jonathan Lloyd Baker

UNLV Theses, Dissertations, Professional Papers, and Capstones

Geochemical models have suggested that the late Cambrian was characterized by a greenhouse climate with high pCO2. Furthermore, stableisotope analyses within the Great Basin have documented a large carbonate isotope (δ13Ccarb) excursion, known as the Steptoean Positive Carbon Isotope Excursion (SPICE). This event has been documented globally, and is interpreted as having resulted from enhanced organic carbon burial. Unless the size of carbon reservoirs in the Cambrian ocean was significantly different from those of the Cenozoic, this forcing should have resulted in a comparable carbon-isotope excursion in organic matter (δ13Corg). It is also predicted that increased organic carbon burial would …

Biogeochemical Investigation Of Soda Lake, Kathryn Bywaters, Shaneen Braswell, David Crowther, Bernadette Leonis, Jeremy Memmott, Farrah Moazeni, Christian H. Fritsen

Undergraduate Research Opportunities Program (UROP)

Big Soda Lake, Nevada, is a terminal, volcanic crater lake whose water level is maintained exclusively by groundwater. The crater is composed of volcanic, basaltic sand and the lake is ~60 m deep (Rush, 1972). The lake is meromictic with a distinct chemocline (Kimmel et al. 1978). The chemocline currently rests at ~40 m and is reflected in both specific conductivity and salinity measurements. Below the chemocline a redox gradient develops with highly reducing conditions. The pH is consistent throughout the depth of the lake at ~9.5, proving that it is alkaline in nature. It is further stratified by both …

Researching Nitrite Oxidation At High Temperatures, Dolores A. Huang, Jeremy A. Dodsworth, Brian P. Hedlund

Undergraduate Research Opportunities Program (UROP)

15N-nitrate (NO3 -) pool dilution experiments show that ammonia (NH3) is oxidized to nitrate in geothermal springs up to at least 85C; however, nitrite (NO2 -)- oxidizing microorganisms are only known to grow up to 66°C. We hypothesize that thermophilic microorganisms oxidize nitrite to nitrate at high temperatures. Alternatively, it is possible that nitrite is oxidized abiotically. We propose to test these hypotheses by setting up microbial enrichments designed to grow thermophilic nitrite oxidizing bacteria by varying incubation temperature (50, 65, 80°C), oxygen concentration (20% and 5%), and cultivation media. A negative control consisting of filtered spring water (0.1 μm) …

The Migration Of Arsenic And Lead In Surface Sediments At Three Kids Mine Henderson, Nevada, Douglas Brian Sims

Publications (WR)

This study focused on the distribution of arsenic and lead in surface sediments at Three Kids Mine in Henderson, Nevada. The mine site encompasses approximately 470 acres of desert and is situated above two developing communities (Lake Las Vegas and Calico Ridge) and the Las Vegas Valley's water source (Lake Mead). Transport of arsenic and lead appears to have occurred within a limited range in both the eastern and western washes on the eastern and western sides of Three Kids Mine. Concentrations of arsenic range between 20 mg/kg (ppm) and 1130 mg/kg and between 20 mg/kg and 8400 mg/kg for …

Synthetic Organic Compounds: Las Vegas Wash And Lake Mead, National Water Quality Assessment Program (Nawqa): Nevada Basin And Range

Publications (WR)

The Nevada Basin and Range (NVBR) study unit of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program is investigating the status of, trends in, and factors affecting water quality in the Las Vegas area. A principal objective of the investigation is to assess the effects of urbanization on the quality of area water resources. Las Vegas Wash is the surface-water outlet for the Las Vegas area. The wash transports stormwater runoff, shallow ground-water discharge, and tertiary-treated sewage effluent from the Las Vegas area to Las Vegas Bay of Lake Mead on the Colorado River. Most of the flow—about 96 …

Water Chemistry Survey Of Boulder Basin, Lake Mead, P. R. Tramutt, Bureau Of Reclamation

Publications (WR)

The survey results indicate that the impoundment of water behind Hoover Dam has not adversely affected the dissolved oxygen (DO) content and that water quality and DO content were uniform regardless of depth. The study made in April-May 1964 will provide water quality data of Lake Mead prior to releases from Lake Powell as a basis for evaluating Lake Powell's effect on water quality and limnology of Lake Mead. The performance of a DO analyzer was tested and found unsatisfactory at depths below 150 ft. Parameters tested by standard chemical analyses of water samples in the Denver Laboratory and by …