Geology topics

Michael Meyer

Publications and source records attributed to Michael Meyer.

4 recordsLinked to original sources

USGS2023

Report of the Science Community Workshop on the proposed First Sample Depot for the Mars Sample Return Campaign

The Mars 2020/Mars Sample Return (MSR) Sample Depot Science Community Workshop was held on September 28 and 30, 2022, to assess the Scientifically-Return Worthy (SRW) value of the full collection of samples acquired by the rover Perseverance at Jezero Crater, and of a proposed subset of samples to be left as a First Depot at a location within Jezero Crater called Three Forks. The primary outcome of the workshop was that the community is in consensus on the following statement: The proposed set of ten sample tubes that includes seven rock samples, one regolith sample, one atmospheric sample, and one witness tube constitutes a SRW collection that: (1) represents the diversity of the explored region around the landing site, (2) covers partially or fully, in a balanced way, all of the International MSR Objectives and Samples Team scientific objectives that are applicable to Jezero Crater, and (3) the analyses of samples in this First Depot on Earth would be of fundamental importance, providing a substantial improvement in our understanding of Mars. At the conclusion of the meeting, there was overall community support for forming the First Depot as described at the workshop and placing it at the Three Forks site. The community also recognized that the diversity of the Rover Cache (the sample collection that remains on the rover after placing the First Depot) will significantly improve with the samples that are planned to be obtained in the future by the Perseverance rover and that the Rover Cache is the primary target for MSR to return to Earth.

Meteoritics and Planetary Science↗

USGS2014

Hand-rearing, growth, and development of common loon ( Gavia immer ) chicks

Common loon chicks were reared in captivity in association with studies to evaluate the effects of radiotransmitter implants and to assess the ecological risk of dietary methylmercury. Here we report on hatching and rearing methods used to successfully raise chicks to 105 days of age. We experienced a 91.5% hatch rate, and 89.6% of loon chicks survived to the end of the study at 105 days. Baseline information on observed rates of fish consumption, behavioral development, and growth patterns are provided. Husbandry techniques are provided that should prove valuable to wildlife rehabilitators caring for abandoned or injured loons, and biologists contemplating methods for restoring loons to areas within their former breeding range.

Zoo Biology↗

USGS2008

Occurrence of chlorothalonil, its transformation products, and selected other pesticides in Texas and Oklahoma streams, 2003-2004

The primary purpose of the study described in this report was to determine if the fungicide chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), three of its transformation products, or selected other pesticides are transported to surface water after use on peanuts or other crops in Texas and Oklahoma. The results summarized here are part of a larger study that includes data from sites in Alabama, Florida, and Georgia. Chlorothalonil is classified as a probable carcinogen, and the 4-hydroxy of chlorothalonil transformation product is more soluble, more stable, and, for some species, more toxic than its parent compound. In 2003, water samples were collected from three surface-water sites in Texas and two surface-water sites in Oklahoma; in 2004, samples were collected from the two Oklahoma sites. Chlorothalonil was not detected in any of the 20 samples analyzed. The 4-hydroxy of chlorothalonil transformation product was detected in three samples collected in 2004, with a maximum concentration of 0.018 microgram per liter (?g/L); the other two transformation products (diamide chlorothalonil and 1-amide-4-hydroxy chlorothalonil) were not detected in any sample. In addition, 19 samples were analyzed for as many as 109 other pesticides and transformation products. Atrazine was detected in 13 samples and had a maximum concentration of 0.122 ?g/L. Deethylatrazine was detected in 10 samples and had a maximum concentration of 0.04 ?g/L. Metolachlor was detected in eight samples and had a maximum concentration of 0.019 ?g/L. Fifteen other pesticides or pesticide transformation products also were detected. In general, concentrations of pesticides were less than concentrations that are commonly observed in Midwestern streams. The results indicate that the use of chlorothalonil on peanut crops has not resulted in substantial contamination of the studied streams in Texas and Oklahoma.

Texas, Oklahoma↗

USGS2006

Research plan and preliminary results: A field research site for emerging contaminants in Iowa

Research has recently documented the prevalence of a wide variety of pharmaceuticals and other emerging contaminants (ECs) in streams across the United States. Wastewater treatment plants (WWTPs) have been found to be an important source and collection point of ECs to streams as many ECs are incompletely removed during treatment. To investigate the complex in-stream processes (e.g., dilution, sorption, degradation, dispersion, etc.) that can affect ECs following their input from a WWTP and determining if such input is having an effect on the aquatic ecosystem requires the integration of multi-disciplinary efforts at a carefully selected field site. Preliminary work has identified an 8-km reach of Fourmile Creek in central Iowa as an ideal research site to investigate such important research questions pertaining to ECs. Unique aspects of Fourmile Creek included: (1) it single source effluent-dominated stream, (2) background data document the input of a wide variety of ECs from WWTP discharge, (3) small basin size, (4) relatively simple flow system, (5) background data suggest that undefined processes are taking place decreasing the level of select ECs during stream transport, (6) the WWTP uses a treatment technology (activated sludge) typical of many towns in Iowa and the United States (7) a hydrogeologic setting of a low-gradient, small stream (average discharge less than 1.41 m³/s) in glacial drift is typical of many areas in Iowa and across the Midwest, and (8) the existence of a low-head clam approximately 2 km upstream of the WWTP outfall allowing more accurate "above WWTP" and "below WWTP" comparisons in aquatic ecosystems. Furthermore, the WWTP is scheduled to close by 2011 providing a unique opportunity to determine how stream hydrology, water chemistry and aquatic biota react to the removal of the primary source of flow and ECs in this system. This will allow a novel "before" and "after" assessment not previously available in EC research. Research to date at the site has included installation of a streamflow gauging station, dye-tracing tests (to determine water travel times), Lagrangian water-quality sampling at two flow/water temperature regimes, and sampling for ECs in bed sediment. Selected fish have been collected for analysis and identification. In addition, basic fish community and fish health assessment for different seasons and spawning conditions are being analyzed. The research "framework" is unique at Fourmile Creek for investigating the important question of how ECs are transported through the environment and if the presence of such compounds is having a deleterious effect on aquatic ecosystems.

Iowa↗