U.S. Geological Survey USGS

Several studies have been conducted to measure methyl parathion in streams, rivers, and lakes. A U.S. Geological Survey (USGS) of western streams detected methyl parathion in five river samples taken from four states during a 14-month period in 1970 and 1971. The amount of methyl parathion detected ranged from 0.04 to 0.23 pg/L (Schultz et al. 1973). A later and more extensive USGS study analyzed water samples from major rivers of the United States four times yearly in the period of 1975-1985. Of the 2,861 water samples, 0.1% had detectable levels of methyl parathion (Gilliom et al. 1985). In a study of Arkansas surface waters, samples of lake and river/stream water were collected and analyzed over a three-year period (Senseman et al. 1997). Of the 485 samples collected, methyl parathion was found in one river/stream sample at a maximum concentration of 3.5 pg/L. Results from an EPA study in California detected methyl parathion in 3 of 18 surface drain effluent samples at concentrations of 10-190 ng/kg. Subsurface drain effluent water had concentrations of 10-170 ng/kg in 8 of 60 samples (lARC 1983). 

Models of the above have been presented by various researchers of the U.S. Geological Survey (USGS) and the academia. The above equation has been solved principally (a) numerically over a temporal and spatial discretized domain, via finite difference or finite element mathematical techniques (e.g., 11) (b) analytically, by seeking exact solutions for simplified environmental conditions (e.g., 12) or (c) probabilistically (e.g., 13). 

U.S. freight shipments, 25 324t U.S. Geological Survey (USGS) data,... 

As part of an orientation study, the U.S. Geological Survey (USGS) collected soils along traverses across the Pebble deposit area. In 2007, soil samples were collected from 78 sites along a 7.8-km east-west traverse over the Pebble East and Pebble... 

Ingersoll, C., Besser, J. and Dwyer, J. (1997) Development and application of methods for assessing the bioavailability of contaminants associated with sediments I. Toxicity and the sediment quality triad, Proceedings of the U S. Geological Survey (USGS) Sediment Workshop, U.S. Geological Survey, Columbia, Missouri (2003-12-22) ... 

The numbers for the United States are as follows. The U.S. Geological Survey (USGS) released a report in 1995 evaluating the U.S. hydrate resource base. It categorized estimates by the level of certainty that they exist.23... 

U.S. Geological Survey (USGS), Quality of Surface Waters of the United States 1956, Parts 1—4, U.S. Geological Survey Water-Supply Paper 1450, USGS, Washington, D.C., 1960. 

Standard reference materials were chosen with matrices that matched those of the samples as nearly as possible. The standards used were a set of U.S. Geological Survey (USGS) silicates G-2, GSP-1, PCC-1, DTS-1, AGV-1, and BCR-1. The elemental composition of these references was determined by DCP... 

According to the U.S. Geological Survey (USGS), in 2008 China led world smelter production of aluminum, followed by Russia, Canada, the United States, Australia, Brazil, and India. 

Copper is mined in more than 50 nations, from Albania and Argentina to Zambia and Zimbabwe. As of 2008, the leading producers are Chile, the United States, Peru, and China. The next largest producers are Australia, Russia, Indonesia, and Canada. According to the U.S. Geological Survey (USGS), about 99 percent of copper mined in the United States comes from Arizona, Utah, New Mexico, Nevada, and Montana. 

An estimated 78 percent of the world s helium was produced in the United States in 2008. Other producers included Algeria, Qatar, Russia, and Poland. Nineteen U.S. plants extracted helium from natural gas. Those plants were located in Colorado, Kansas, New Mexico, Oklahoma, Texas, Utah, and Wyoming. According to the U.S. Geological Survey (USGS), between 2009 and 2015, about nine new helium plant projects are slated to begin work worldwide. Such plants will be located in the United States (2), Algeria, Australia, China, India, Indonesia, Qatar, and Russia. 

Molybdenum never occurs free in nature. Instead, it is always part of a compound. In addition to molybdenite, it occurs commonly as the mineral wulfenite (PbMo04). Its abundance in Earth s crust is estimated to be about 1 to 1.5 parts per million. That makes it about as common as tungsten and many of the rare earth (lanthanoid) elements. In 2008, the largest producers of molybdenum in the world included the United States, China, Chile, Peru, and Canada. In the United States, molybdenum ores were found primarily in Colorado, Idaho, Nevada, and New Mexico. According to the U.S. Geological Survey (USGS), the value of the molybdenum from U.S. mines was 4.5 billion that year. 

---