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Environmental Radiation

Grand Canyon Horn Creek

RadWatch postdoc Brian Plimley was backpacking in the Grand Canyon in November 2016 near Horn Creek, a stream marked on park maps as "Do Not Drink" as a result of an old uranium mine at the canyon rim above the creek. Brian was able collected samples of water and sediment from Horn Creek to be measured at the LBL Low-Background Facility. The results of those measurements are included in this article along with some discussion of what they tell us.
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USS Independence Survey

Our very own Christopher Figueroa accompanied a group of scientists on an expedition to observe and gather samples from the wreck of the USS Independence, a World War II aircraft carrier used as a target in the 1946 atomic bomb test at Bikini Atoll. This report describes the measurements of ocean sponge and their results.
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Updated Sampling Measurements

The RadWatch Gamma Sampling Data has been updated to include a wider range of environmental samples from our most recent measurements of fish, seawater, and even pork products, and using a new analysis method to verify and improve on past results. Details describing the procedure for preparing and measuring samples to obtain the data presented are now described in our new Methods Page. All of this data and older results are stored through various links found through the Sampling Data Page.
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RadWatch site featured on Berkeley.edu!

Radioactivity is all around us, and UC Berkeley researchers want the public to know it. Read more about RadWatch, as featured on the UC Berkeley News Center Website.

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Half Moon Bay Measurements: Quantitative Sand Analysis (Follow Up)

As a follow up to our recent measurements at Half Moon Bay, we wanted to quantitatively measure some of the samples we took along the beach. Previously, we found that mostly Uranium and Thorium isotopes were contributing to the increased count rate along the beach, and we wanted to measure the concentrations of these isotopes present in the sand.

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Seaweed Measurements (2013)

These seaweed samples were provided to our group by a seaweed harvesting company located in Northern California as a continuation of a study beginning in spring 2011. As in previous years, we tested the samples using a high purity germanium (HPGe) detector in Etcheverry Hall, UC Berkeley. HPGe detectors have very high spectral resolution, meaning they are able to distinguish the gamma-ray lines coming from different radioactive isotopes. For seaweed this is especially important because there is typically a large amount of the naturally occurring isotope potassium-40 (K-40).

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Results of Red Salmon from Alaska caught in 2011, 2012, and 2013

Three samples of Red Salmon from Alaska have been tested. The salmon was caught at the same location (the Kenai River) in July for each of the last three years-- 2011, 2012, 2013! A small amount of Fukushima-sourced radio-cesium was found in the July 2011 sample, likely from the initial airborne releases of radioactivity in Spring of 2011. No Fukushima-related radioisotopes were found in the 2012 and 2013 samples. In all samples, naturally radioactive potassium dominated the gamma spectrum. Bi-214 and Pb-210 are also naturally occurring radio-isotopes. Most of the Cs-137 originates from releases before Spring 2011.

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