The standard atomic weights of nineteen elements have been changed as the result of cooperative research supported by the U.S. Geological Survey and the International Union of Pure and Applied Chemistry (IUPAC). The new values were announced at the August 2013 meeting of the IUPAC Commission on Atomic Weights and Isotopic Abundances held in Gebze, Turkey.
The standard atomic weights of molybdenum, cadmium, selenium, and thorium have been changed based on recent determinations of terrestrial isotopic abundances. In addition, the standard atomic weights of 15 elements have been revised based on a new assessment of their atomic masses by the International Union of Pure and Applied Physics.
Changes in standard atomic weights:
molybdenum: from 95.96(2) to 95.95(1)
cadmium: from 112.411(8) to 112.414(4)
selenium: from 78.96(3) to 78.971(8)
thorium: from 232.038 06(2) to 232.0377(4)
beryllium: from 9.012 182(3) to 9.012 1831(5)
fluorine: from 18.998 4032(5) to 18.998 403 163(6)
aluminium (aluminum): from 26.981 5386(8) to 26.981 5385(7)
phosphorus: from 30.973 762(2) to 30.973 761 998(5)
scandium: from 44.955 912(6) to 44.955 908(5)
manganese: from 54.938 045(5) to 54.938 044(3)
cobalt: from 58.933 195(5) to 58.933 194(4)
arsenic: from 74.921 60(2) to 74.921 595(6)
yttrium: from 88.905 85(2) to 88.905 84(2)
niobium: from 92.906 38(2) to 92.906 37(2)
caesium (cesium): from 132.905 4519(2) to 132.905 451 96(6)
praseodymium: from 140.907 65(2) to 140.907 66(2)
holmium: from 164.930 32(2) to 164.930 33(2)
thulium: from 168.934 21(2) to 168.934 22(2)
gold: from 196.966 569(4) to 196.966 569(5)
These changes will be published in 2014 by IUPAC in the journal Pure and Applied Chemistry as a new "Table of Standard Atomic Weights 2013."
Currently, the revised values for atomic weights can be found on-line in the Table of Standard Atomic Weights (xls) at the website of the Commission on Isotopic Abundances and Atomic Weights.
The importance of determining precise atomic weights has long been recognized. As far back as 1882, Frank W. Clarke, then a professor at the University of Cincinnati, prepared a table of atomic weights for use in science, industry, and trade. He carried on this work as Chief Chemist of the USGS (1883-1924). Clarke was a founder of the American Chemical Society and a member of the National Academy of Sciences. Recently, IUPAC has overseen the periodic evaluation and dissemination of atomic-weight values.
The U.S. Geological Survey has developed a hydrologic modeling tool that will aid planning for water-supply sustainability and preparing for the potential impacts of climate change in regional coastal aquifer systems.
The depletion of groundwater and the compounding effects of recent droughts have led to concerns about the future availability of fresh groundwater in coastal areas. Coastal areas are particularly at risk because population densities are higher there than inland with at least 40% of the U.S. population living within 50 miles of the coast. Federal, state, and local water managers and decision makers are increasingly being asked to make critical decisions about important issues concerning supply and demand of water resources that cross political boundaries.
In a collaborative effort among USGS, academia, and the private sector, a new modeling tool, called the Seawater Intrusion (SWI2) Package, was developed for the popular USGS MODFLOW-2005 groundwater modeling program. As the most widely used groundwater flow model in the world, MODFLOW features a comprehensive range of options for simulating many different hydrologic components.
With the addition of the SWI2 Package, MODFLOW-2005 can now be used to quickly and accurately predict the effects of human (groundwater withdrawals) and environmental (landscape change and climate variability) stressors on the position and movement of the saltwater and freshwater interface in regional coastal aquifer systems. By simulating seawater intrusion processes many times faster than with current detailed approaches, the SWI2 Package provides water managers with an integrated view of the regional aquifer system that enables them to quickly evaluate how changes to the system may affect future fresh groundwater availability.
Most available software packages for modeling seawater intrusion are highly complex, computationally intensive, and do not contain comprehensive modeling utilities required for coastal groundwater flow problems.
The SWI2 Package is currently being applied in several studies of coastal aquifers in Florida. For example, in a study focused on evaluating the effect of groundwater pumpage on surface-water canal leakage, the SWI2 Package allowed the authors of the study to evaluate the combined effect that increased groundwater pumpage and rising sea level would likely have on the location of the freshwater-seawater interface with time. Application of this new SWI2 package enabled a timely, cost-efficient solution to the problem while accurately representing the system response.
The USGS through the Groundwater Resources Program is conducting large-scale multidisciplinary regional studies of groundwater availability in the Nation. Collectively, these studies, conducted in cooperation with other Federal, state, and local governments, are the foundation for a national assessment of groundwater availability. Groundwater-flow models are used in these studies to evaluate the effects of human activities and climate variability on groundwater levels, changes in aquifer storage, and flow between groundwater and surface-water bodies. Development of the SWI2 modeling tool is one example of the scientific innovations being generated as a byproduct of this national assessment.
USGS groundwater modeling software is available free-of-charge to the public. The Seawater Intrusion (SWI2) Package, which is available within the MODFLOW-2005 program, is fully documented and accessible at USGS Ground-Water Software website.
The USGS continues to lead in the development and application of computer software that allows groundwater models to address complex scientific and management questions. Building a strong USGS groundwater model component helps improve the current understanding of the Nation's groundwater resource and supports the Water Census for the United States. The Water Census is a broad USGS initiative aimed at providing citizens, communities, natural-resource managers, and policymakers with a clear knowledge of the status of their water resources, data on trends in water availability and use over recent decades, and an improved ability to forecast the availability of freshwater for future human, economic, and environmental uses.
The USGS methodology for assessing carbon dioxide (CO2) storage potential for geologic carbon sequestration was endorsed as a best practice for a country-wide storage potential assessment by the International Energy Agency (IEA).
The IEA report announcing the endorsement reflects the consensus reached at two workshops in 2011 and attended by the geological surveys of Australia, Canada, Germany, Japan, the Netherlands, the United Kingdom, and the United States, together with the IEA.
"We are definitely honored by the recognition given to us by the IEA and the confidence the international science community has in our assessment methodology," said USGS scientist Sean Brennan, lead representative from the USGS at the workshops. "One of the things we all agreed upon at the workshops was that a consistent approach was very important so as to allow assessments to be compared across countries."
The USGS approach was praised for several primary reasons:
- The assessment relies on a probabilistic methodology, which incorporates statistics to make resource estimates. The benefit of a probabilistic approach is that it allows for the resource to be assessed with any given level of uncertainty in the data collected.
- The USGS based its assumptions on today’s available technology and standard industry practices. Using current techniques allows the assessment to have as close to a realistic result as possible.
- The USGS approach is geologically based, as the rock layers included in the assessment were limited to those determined to have sufficient natural seals to prevent CO2 from escaping.
The USGS released its first national assessment of technically accessible geologic carbon dioxide storage potential in June of 2013. According to that assessment, the United States has the potential to store a mean of 3,000 metric gigatons of CO2 in geologic basins throughout the country. This national assessment complements the regional estimates that the Department of Energy includes in their periodically updated Atlas.
"The report represents the result of over 2 year of international collaboration between the involved geological survey organizations," said Wolf Heidug, Senior Energy Analyst for the IEA. "The support and expertise of USGS have been essential throughout this process. The recommendations made for best practices build on key features of the assessment methodology developed by USGS to allow for a transparent and robust assessment of geological storage resource throughout the world."
The IEA report recommended three approaches in total. The USGS approach was recommended for an initial, country-wide assessment of technically available storage resources. The approaches developed by the German Federal Institute for Geosciences and Natural Resources and Geological Survey of the Netherlands were recommended for more site-specific approaches that took specific policies into account.
The IEA is an autonomous organization which works to ensure reliable, affordable and clean energy for its 28 member countries and beyond. The IEA's four main areas of focus are: energy security, economic development, environmental awareness, and engagement worldwide.
To learn more about this or other geologic assessments, please visit the USGS Energy Resources Program website. Stay up to date with USGS energy science by subscribing to our newsletter or by following us on Twitter.
The USGS has developed a tiered chemical prioritization approach that can be used by local, state, and federal agencies to develop ambient water and sediment quality monitoring strategies. Over 2,450 chemicals were prioritized based on their likelihood of adverse effects on human health or aquatic life, combined with information on likelihood of environmental occurrence.
Ambient monitoring includes studies of the quality of environmental resources (such as water or sediment) that are conducted under typical conditions without a predisposition that contamination is present.
"The information and approaches described in this study can be used by water resource managers to develop improved strategies that focus limited monitoring dollars on chemicals that, if present at high enough concentrations, can adversely affect human or ecosystem health," said Lisa Olsen, USGS hydrologist who led the study.
Dr. Helen Goeden, a senior toxicologist with the Minnesota Department of Health (MDH), stated that staff within the MDH's Contaminants of Emerging Concern (CEC) program has used the information described in the USGS study to assist in identifying and ranking contaminants for assessment within the CEC program.
The range of chemicals reviewed includes organic compounds of human origin and chemicals from natural sources, such as radionuclides and trace elements from geologic materials. Of 2,451 chemicals prioritized, 1,081 were determined to be of the highest priority or "Tier 1" for ambient monitoring, including 602 for water and 686 for sediment (some were evaluated for both matrixes). Others were assigned to Tier 2, those having intermediate priority for monitoring on the basis of a lower likelihood of occurrence or lower likelihood of effects on human health or aquatic life, or to Tier 3, those have low or no priority for monitoring.
Groups of chemicals prioritized for this effort included:
- Volatile organic compounds in water – 85
- Pesticides and degradates in water – 615
- Pesticides and degradates in sediment – 605
- Pharmaceuticals and hormones in water or sediment – 405
- Trace elements and other inorganics in water – 38
- Trace elements in sediment – 10
- Cyanotoxins in surface water – 15
- Lipophilic organic compounds in sediment – 699
- Disinfection by-products in water – 93
- High-production-volume chemicals in water – 318
- Wastewater-indicator and industrial compounds in water – 470
- Radionuclides in water – 14
This study was done to help the National Water-Quality Assessment (NAWQA) Program prepare for its third decade of monitoring the Nation's surface and groundwater resources. For example, NAWQA monitoring of surface and groundwater resources is using analytical schedules that include 350 of the 602 Tier 1 chemicals recommended for ambient water-quality monitoring.
The study is based on information from NAWQA and other USGS programs, information on chemicals of human-health and aquatic-life concern compiled by other agencies and organizations, U.S. Environmental Protection Agency databases, and peer-reviewed literature, totaling over 800 references. Results of the prioritization effort and related analytical methods used by the NAWQA Program are compiled in USGS Scientific Investigations Report 2012-5218.
A new report by the U.S. Geological Survey evaluates how well the USGS streamgage network meets needs for streamflow information by assessing the ability of the network to produce various streamflow statistics at locations that have streamgages (gaged) and that do not have streamgages (ungaged).
The report analyzes where there are gaps in the network of gaged locations, how accurately useful statistics can be calculated with a given length of record, and whether the current network allows for estimation of these statistics at ungaged locations. The results of the report indicate that there is variability across the Nation’s streamflow data-collection network in terms of the spatial and temporal coverage of streamgages.
In general, the eastern United States has better coverage than the western U.S. The arid southwestern U.S., Alaska, and Hawaii were observed to have the poorest spatial coverage, using the dataset assembled for this study. With the exception of Hawaii, these areas also tended to have short streamflow records.
Differences in hydrology lead to differences in the uncertainty of statistics calculated in different regions of the country. Arid and semiarid areas of the central and southwestern U.S. generally exhibited the highest levels of interannual variability in flow, leading to larger uncertainty in flow statistics at both gaged and ungaged locations.
At ungaged locations, information can be transferred from nearby streamgages if there is sufficient similarity between the gaged watersheds and the ungaged watersheds of interest. Areas where streamgages exhibit high correlation with other streamgages are most likely to be suitable for this type of information transfer. The areas with the most highly correlated streamgages appear to coincide with mountainous areas of the U.S. Lower correlations are found in the central U.S. and coastal areas of the southeastern U.S.
Information transfer from gaged basins to ungaged basins is also most likely to be successful when basin attributes show high similarity. At the scale of the analysis completed in this study, the attributes of basins upstream of USGS streamgages cover the full range of basin attributes observed at potential locations of interest fairly well. Some exceptions included very high or very low elevation areas and very arid areas.
- A national streamflow network gap analysis
USGS Scientific Investigations Report: 2013-5013
- USGS Surface Water Information
- USGS National Streamflow Information Program (NSIP)
- National Water Census
Wastewater treatment plants that process waters from oil and gas development were found to discharge elevated levels of toxic chemicals known as brominated disinfection byproducts, according to a new study by the U.S. Geological Survey.
Disinfection byproducts are created by chemical reactions when water is disinfected. Of the hundreds of known, or suspected, disinfection byproducts possibly created by disinfection processes, the brominated forms are among the most toxic.
"While these findings do not indicate an immediate threat to aquatic life or human health, the study provides new data on the water quality of streams receiving discharged wastewater that can be used to inform decisions about management and treatment of produced waters," said Michelle Hladik, primary author of the report.
Waters that are co-produced when oil and gas resources are extracted from deep geological formations are commonly called produced waters. Produced waters are composed of naturally occurring materials characteristic of the geologic formations in which they originate. Often, the water in these formations is a brine with high concentrations of bromide, iodide, and other ions such as sodium and chloride.
Produced waters can originate from unconventional (e.g. hydraulic fracturing) and conventional oil and gas extractions. Management of produced waters includes a variety of methods, such as recycling, road spreading, deep-well injection, and processing by wastewater treatment plants.
Several different types of brominated disinfection byproducts can be created when produced waters with high levels of bromide are disinfected.
Currently, and during the time of the study, most wastewaters from unconventional oil and gas activities such as hydraulic fracturing in the study area have been deep well injected and therefore not processed by wastewater treatment plants. However, this study did not attempt to quantify the relative proportions of produced waters originating from the various unconventional or conventional oil and gas extraction activities.
The study examined river water samples downstream from the discharges of publicly-owned and commercial wastewater treatment plants that were processing produced waters with high levels of naturally occurring bromide. These samples were compared with water just upstream of the plants and with samples from wastewater treatment plants that did not process produced waters from oil and gas development.
The water was examined for 29 different disinfection byproducts, including brominated and non-brominated disinfection byproducts. The brominated disinfection byproducts were detected more frequently and at much higher levels in river water impacted by disinfected produced waters than at other sites.
The study is entitled "Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams," and is published in Science of the Total Environment. The study may be accessed online.
The USGS provides information on the quality of our environment; identifies emerging environmental issues; and provides information to aid decision-making by regulators, policymakers, industry and the public. To learn more about this study and other USGS Environmental Health research, please visit the USGS Environmental Health website or sign up for the USGS GeoHealth Newsletter.
The U.S. Geological Survey has developed analysis software to facilitate research of chemical mixtures. The new software consists of four computer programs to help hydrologists, toxicologists, and other professionals investigate chemical mixtures in the environment.
The study of mixtures is difficult due to the enormous number of environmental mixtures. The number of mixtures increases rapidly with the number of co-occurring chemicals.
"Studying chemical mixtures is important because most organisms, including people, are exposed to mixtures in their environments, and little is known about their potential health effects," said Jon Scott, a retired USGS scientist and primary author. "The software includes tools for investigating which chemicals are found in mixtures, how often the mixtures occur in the environment, and the concentrations of mixture components relative to various health benchmarks."
The new tool is documented in the on-line report, Software for Analysis of Chemical Mixtures—Composition, Occurrence, Distribution, and Possible Toxicity, by Jonathon Scott, Kenneth Skach, and Patricia Toccalino. The software described in the report, along with other USGS programs, can be obtained online.
The mixture-analysis software was developed by the USGS National Water Quality Assessment (NAWQA) Program to document methods for mixture analysis and serve as a foundation for future studies. The NAWQA Program conducts regional and national assessments of the Nation’s water quality to provide an understanding of water-quality conditions, whether conditions are getting better or worse over time, and how natural features and human activities affect those conditions.
Shale and other clay-rich rock formations might offer permanent disposal solutions for spent nuclear fuel, according to a new paper by the U.S. Geological Survey. There is currently about 70,000 metric tons of this spent fuel in temporary storage across the United States.
While no specific sites have been evaluated for storage potential in the United States, USGS scientists have looked at several research efforts, including projects that are underway in France, Belgium and Switzerland to confirm that shale formations in those countries are favorable for hosting nuclear waste repositories.
"Deciding how to safely dispose of spent nuclear fuel and other high-level nuclear waste is a very important issue that is not going to go away," said Chris Neuzil, the article's author. "Although shales and similar rocks have not been considered for hosting nuclear waste in the United States, recent research points to them as a very promising option."
Shale formations are attractive for nuclear waste storage for several reasons. First and foremost, they have extremely low permeability, meaning groundwater cannot easily flow through them. Most shale formations and similar rocks containing abundant clay are millions to tens of billions of times less permeable than aquifers that are used to supply water.
The primary concern with radioactive waste underground is to prevent any groundwater that contacts it from carrying contaminants out of the repository. Formations with very low permeability significantly reduce the potential for that contamination to occur. It is also important to ensure that water-transmitting fractures are absent over large areas, and in many shales it appears possible to do this.
Some shale formations are marked by groundwater pressures that are unusually low, which causes the rock to act something like an absorbent sponge. Groundwater is being slowly but constantly drawn into the formation, further reducing the chance of contaminants escaping.
Clay-rich formations also function as filters and are absorptive. Contaminants in groundwater that flows through them are held back and many bind to the clay.
Potentially usable shale formations in the United States—those without extractable energy resources or other prohibitive circumstances—are distributed widely across the country and many are in tectonically stable areas. Geologically and geographically, potential choices for a repository are many.
The article is entitled "Can Shale Safely Host U.S. Nuclear Waste?" and is published in EOS, a journal by the American Geophysical Union. More information on this article and other water research can be found at the USGS Water National Research Program website.
On June 5, 2013, the U.S. Geological Survey Flight Operations Team transmitted the last command to the Landsat 5 satellite, effectively terminating the mission 29 years, 3 months and 4 days after its launch by NASA from Vandenberg Air Force Base on March 1, 1984. The Landsat program is a joint effort between USGS and NASA.
Landsat 5 had orbited the planet over 150,000 times while transmitting over 2.5 million images of land surface conditions around the world, long outliving its original three-year design life. In December 2012, USGS announced that Landsat 5 would be decommissioned. The durable satellite is recognized by the Guinness Book of Records as the longest-operating Earth-observing satellite mission in history.
Landsat 5 beamed its last image down to the USGS Earth Resources Observation and Science (EROS) Center in Sioux Falls, SD, on January 6, 2013. Nine days later, Mission Operations began the methodical process of maneuvering the satellite from its 438 mile-high operational orbit into a lower disposal orbit. With Landsat 5's fuel reserve completely depleted, the Operations team issued commands on June 5 to shut off all moving mechanisms and hobble the spacecraft’s ability to generate and store power from its solar arrays. The final command shut down Landsat 5’s transmitter, silencing the mission permanently.
For nearly a year the USGS team methodically planned a complex series of steps that were necessary to ensure that the satellite's decommissioning would meet the requirements set under international agreements. When the planning began, a date for decommissioning had not yet been set, but the failure of a critical component last November forced USGS managers to direct that the mission be ended as soon as practicable.
Landsat 5 recorded many significant events. It was the first satellite to image the nuclear accident at Chernobyl in 1986; it documented the massive rainforest deforestation occurring in tropical regions; and it captured the devastating tsunami in southeast Asia in 2004.
Seemingly right on cue, the newest remote sensing mission, Landsat 8 — launched by NASA on February 11 and then checked out in orbit — was transferred to the USGS on May 30 to begin operations in the orbital slot previously held by Landsat 5.
Landsat 8 orbits Earth once every 99 minutes at an average altitude of 438 miles, repeating the same ground track every 16 days. As Landsat 8 joins Landsat 7 in imaging the Earth, researchers and natural resource managers will once again be able to receive Landsat data every eight days for any given location. Many Landsat users depend on a short repeat cycle for prompt data on resources such as agricultural crops, forests, and water.
Current and historical data from the entire series of Landsat satellites (since 1972) is available from the USGS-EROS Earth observation archive free of charge.
- USGS Landsat Missions (latest satellite status, how to obtain data)
- NASA Landsat information (selected imagery, feature articles)
- What is the Economic Value of Satellite Imagery? (USGS Professional Paper)
- NASA-USGS 40th Anniversary of Landsat