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This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-TKs Toolik Shrub Tundra. This is the FLUXNET version of the carbon flux data for the site US-TKs Toolik Shrub Tundra produced by applying the standard ONEFlux (1F) software. Site Description - Long term site of snow fence manipulation experiment in shrub tundra ecosystem
In this article, we describe the seismoacoustic wavefield recorded outdoors but inside the facility fence of the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (Tennessee). HFIR is a research nuclear reactor that generates neutrons for scattering, irradiation research, and isotope production. This reactor operates at a nominal power of 85 MW, with a full-power period between 24 and 26 days. This study uses data from a single seismoacoustic station that operated for 60 days and sampled a full operating reactor cycle, that is, full-power operation and end-of-cycle outage. The analysis presented here is based on identifying signals that characterize the steady, that is, full-power operation and end-of-cycle outage, and transitional, that is, start-up and shutdown, states of the reactor. We found that the overall seismoacoustic energy closely follows the main power cycle of the reactor and identified spectral regions excited by specific reactor operational conditions. In particular, we identified a tonal noise sequence with a fundamental frequency around 21.4 Hz and multiple harmonics that emerge as the reactor reaches 90% of nominal power in both seismic and acoustic channels. We also utilized temperature measurements from the monitoring system of the reactor to suggest links between the operation of reactor’s subsystems and seismoacoustic signals. We demonstrate that seismoacoustic monitoring of an industrial facility can identify and track some industrial processes and detect events related to operations that involve energy transport.
This report serves as the combined annual report for post-closure activities for the following closed Corrective Action Units (CAUs): • CAU 90, Area 2 Bitcutter Containment; • CAU 91, Area 3 U-3fi Injection Well; • CAU 92, Area 6 Decon Pond Facility; • CAU 110, Area 3 WMD U-3ax/bl Crater; and • CAU 112, Area 23 Hazardous Waste Trenches. This report covers fiscal year 2011 (October 2010-September 2011). The post-closure requirements for these sites are described in Resource Conservation and Recovery Act Permit Number NEV HW0101 and summarized in each CAU-specific section in Section 1.0 of this report. Site inspections are conducted semiannually at CAUs 90 and 91 and quarterly at CAUs 92, 110, and 112. Additional inspections are conducted at CAU 92 if precipitation occurs in excess of 0.50 inches in a 24-hour period. Inspections include an evaluation of the condition of the units and identification of any deficiencies that may compromise the integrity of the units. The condition of covers, fencing, signs, gates, and locks is documented. In addition, soil moisture monitoring and subsidence surveys are conducted at CAU 110. The results of the inspections, summary of maintenance activities, results of vegetations surveys, and analysis of monitoring data are presented in this report. Copies of the inspection checklists are included as Appendix A. Field notes completed during each inspection are included in Appendix B. Photographs taken during the inspections are included in Appendix C. It is recommended to continue semiannual inspections at CAUs 90 and 91; quarterly inspections at CAUs 92, 110, and 112; and additional inspections at CAU 92 if precipitation occurs in excess of 0.50 inches in a 24-hour period. At CAU 92, it is recommended to remove the wave barriers, as they have not proven to be necessary to protect the cover. At CAU 110, it is recommended to continue annual vegetation monitoring and soil moisture monitoring, and to reduce the frequency of subsidence surveys from twice per year to once every other year (biennially).
A total length of 36.7 kilometers of riparian habitat were inventoried within LANL boundaries between 2007 and 2011. The following canyons and lengths of riparian habitat were surveyed and inventoried between 2007 and 2011. Water Canyon (9,669 m), Los Alamos Canyon (7,131 m), Pajarito Canyon (6,009 m), Mortandad Canyon (3,110 m), Two-Mile Canyon (2,680 m), Sandia Canyon (2,181 m), Three-Mile Canyon (1,883 m), Canyon de Valle (1,835 m), Ancho Canyon (1,143 m), Canada del Buey (700 m), Sandia Canyon (221 m), DP Canyon (159 m) and Chaquehui Canyon (50 m). Effluent Canyon, Fence Canyon and Potrillo Canyon were surveyed but no areas of riparian habitat were found. Stretches of inventoried riparian habitat were classified for prioritization of treatment, if any was recommended. High priority sites included stretches of Mortandad Canyon, LA Canyon, Pajarito Canyon, Two-Mile Canyon, Sandia Canyon and Water Canyon. Recommended treatment for high priority sites includes placement of objects into the stream channel to encourage sediment deposition, elimination of channel incision, and to expand and slow water flow across the floodplain. Additional stretches were classified as lower priority, and, for other sites it was recommended that feral cattle and exotic plants be removed to aid in riparian habitat recovery. In June 2011 the Las Conchas Wildfire burned over 150,000 acres of land in the Jemez Mountains and surrounding areas. The watersheds above LA Canyon, Water Canyon and Pajarito Canyon were burned in the Las Conchas Wildfire and flooding and habitat alteration were observed in these canyon bottoms (Wright 2011). Post fire status of lower priority areas may change to higher priority for some of the sites surveyed prior to the Las Conchas Wildfire, due to changes in vegetation cover in the adjacent upland watershed.
This Closure Report (CR) presents information supporting closure of Corrective Action Unit (CAU) 547, Miscellaneous Contaminated Waste Sites, and provides documentation supporting the completed corrective actions and confirmation that closure objectives for CAU 547 were met. This CR complies with the requirements of the Federal Facility Agreement and Consent Order (FFACO) that was agreed to by the State of Nevada; the U.S. Department of Energy (DOE), Environmental Management; the U.S. Department of Defense; and DOE, Legacy Management (FFACO, 1996 as amended). CAU 547 consists of the following three Corrective Action Sites (CASs), located in Areas 2, 3, and 9 of the Nevada National Security Site: (1) CAS 02-37-02, Gas Sampling Assembly; (2) CAS 03-99-19, Gas Sampling Assembly; AND (3) CAS 09-99-06, Gas Sampling Assembly Closure activities began in August 2011 and were completed in June 2012. Activities were conducted according to the Corrective Action Decision Document/Corrective Action Plan (CADD/CAP) for CAU 547 (U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office [NNSA/NSO], 2011). The recommended corrective action for the three CASs in CAU 547 was closure in place with administrative controls. The following closure activities were performed: (1) Open holes were filled with concrete; (2) Steel casings were placed over vertical expansion joints and filled with cement; (3) Engineered soil covers were constructed over piping and exposed sections of the gas sampling system components; (4) Fencing, monuments, Jersey barriers, radiological postings, and use restriction (UR) warning signs were installed around the perimeters of the sites; (5) Housekeeping debris was picked up from around the sites and disposed; and (6) Radiological surveys were performed to confirm final radiological postings. UR documentation is included in Appendix D. The post-closure plan was presented in detail in the CADD/CAP for CAU 547 and is included as Appendix F of this report. The requirements are summarized in Section 5.2 of this report. The proposed post-closure requirements consist of visual inspections to determine the condition of postings and radiological surveys to verify contamination has not migrated. NNSA/NSO requests the following: (1) A Notice of Completion from the Nevada Division of Environmental Protection to NNSA/NSO for closure of CAU 547; and (2) The transfer of CAU 547 from Appendix III to Appendix IV, Closed Corrective Action Units, of the FFACO.
Beginning with the Manhattan Project, the earliest work with radioactive material was located in what is now the center of Los Alamos townsite, and some of those materials were released into the environment or disposed of as waste. These radioactive materials have been extensively studied and assessed in many reports during the past 60 years. The assessments consider many activities relevant to dose assessment, such as adventurous children who burrow into and eat the soil, as well as the activities of pets and wildlife. Even for the most extreme scenarios, the doses are less than a few mrem per year, well below the DOE limit for the public, and four orders of magnitude below the DOE limit to terrestrial animals, which is 0.1 rad per day. Locations that pose even a very small risk to humans or pets are fenced, locked, and posted as controlled areas. However, it is recognized that biota such as plants, birds, mice, and worms live in these controlled areas. The DOE standard is intended to protect these biota. Contaminated sites in and near Los Alamos consist of areas known as solid waste management units (SWMU) and areas of concern (AoC) that have been identified and studied extensively in many reports. LA-UR-90-4300 lists these locations, and many subsequent reports provide extensive details and assessments. Between these areas, the levels of detectable radioactive materials are many orders of magnitude smaller. Because they are not a focus of concern, the areas outside of SWMUs and AoCs have not been as extensively studied or sampled. The highest concentrations of radioactive materials resulting from historic LANL operations are buried in material disposal areas (MDAs) such as MDA A, B, C, G, T, etc. Much of this material is sealed in containers that are not accessible to biota (McNaughton 2005). In some cases, it is buried below the reach of tree roots or burrowing animals, and in some cases it is encased or embedded in concrete. Of particular relevance to the present report, the hills to the west of LANL, where the Las Conchas fire burned, are not contaminated with LANL‐derived substances. The radioactivity in these hills consists of naturally occurring radioactive material (NORM) and global fallout.
Kontek Industries (Kannapolis, NC) and their subsidiary, Stonewater Control Systems (Kannapolis, NC), have entered into a cooperative research and development agreement with Sandia to jointly develop and evaluate an integrated perimeter security system solution, one that couples access delay with detection and assessment. This novel perimeter solution was designed to be configurable for use at facilities ranging from high-security military sites to commercial power plants, to petro/chemical facilities of various kinds. A prototype section of the perimeter has been produced and installed at the Sandia Test and Evaluation Center in Albuquerque, NM. This prototype system integrated fiber optic break sensors, active infrared sensors, fence disturbance sensors, video motion detection, and ground sensors. This report documents the design, testing, and performance evaluation of the developed ReKon system. The ability of the system to properly detect pedestrian or vehicle attempts to bypass, breach, or otherwise defeat the system is characterized, as well as the Nuisance Alarm Rate.
This report presents results of data collected during the annual post-closure site inspections conducted at the Central Nevada Test Area surface Corrective Action Unit (CAU) 417 in May 2011 and July 2012. The annual post-closure site inspections included inspections of the UC-1, UC-3, and UC-4 sites in accordance with the Post-Closure Monitoring Plan provided in the CAU 417 Closure Report (NNSA/NV 2001). The annual inspections conducted at the UC-1 Central Mud Pit (CMP) indicated that the site and soil cover were in good condition. No new fractures or extension of existing fractures were observed and no issues with the fence or gate were identified. The vegetation on the cover continues to look healthy, but the biennial vegetation survey conducted during the 2012 inspection indicated that the total foliar cover was slightly higher in 2009 than in 2012. This may be indicative of a decrease in precipitation observed during the 2-year monitoring period. The precipitation totaled 9.9 inches from July 1, 2010, through June 30, 2011, and 5 inches from July 1, 2011, through June 30, 2012. This decrease in precipitation is also evident in the soil moisture data obtained from the time domain reflectometry sensors. Soil moisture content data show that the UC-1 cover is performing as designed, and evapotranspiration is effectively removing water from the cover.
This letter serves as the post-closure inspection letter report for Corrective Action Units (CAUs) on the Nevada National Security Site for calendar year 2013. The inspections identified maintenance and repair is required at the following sites: sign and/or fence repair is necessary at CAUs 113, 137, 139, 140, 143, 262, 370, 371, 372, 374, 476, 478, 529, 542, and 560; animal burrows were identified at CAU 547; and erosion was identified at CAUs 366, 367, 383, 551, and 574. In addition, the following use restrictions were removed during 2013 and will no longer be inspected in 2014: 165, 357, and 528.
This report serves as the combined annual report for post-closure activities for several Corrective Action Units (CAUs). The locations of the sites are shown in Figure 1. This report covers fiscal year 2014 (October 2013–September 2014). The post-closure requirements for these sites are described in Resource Conservation and Recovery Act Permit Number NEV HW0101 and summarized in each CAU-specific section in Section 1.0 of this report. The results of the inspections, a summary of maintenance activities, and an evaluation of monitoring data are presented in this report. Site inspections are conducted semiannually at CAUs 90 and 91 and quarterly at CAUs 92, 110, 111, and 112. Additional inspections are conducted at CAU 92 if precipitation occurs in excess of 0.50 inches (in.) in a 24-hour period and at CAU 111 if precipitation occurs in excess of 1.0 in. in a 24-hour period. Inspections include an evaluation of the condition of the units, including covers, fences, signs, gates, and locks. In addition to visual inspections, soil moisture monitoring, vegetation evaluations, and subsidence surveys are conducted at CAU 110. At CAU 111, soil moisture monitoring, vegetation evaluations, subsidence surveys, direct radiation monitoring, air monitoring, radon flux monitoring, and groundwater monitoring are conducted. The results of the vegetation surveys and an analysis of the soil moisture monitoring data at CAU 110 are presented in this report. Results of additional monitoring at CAU 111 are documented annually in the Nevada National Security Site Waste Management Monitoring Report Area 3 and Area 5 Radioactive Waste Management Sites and in the Nevada National Security Site Data Report: Groundwater Monitoring Program Area 5 Radioactive Waste Management Site, which will be prepared in approximately June 2015. All required inspections, maintenance, and monitoring were conducted in accordance with the post-closure requirements of the permit. It is recommended to continue inspections and monitoring as scheduled.
The major research goal of this project was to understand and quantify the fate of carbon stored in permafrost ecosystems using a combination of field and laboratory experiments to measure isotope ratios and C fluxes in a tundra ecosystem exposed to experimental warming. Field measurements centered on the establishment of a two-factor experimental warming using a snow fence and open top chambers to increase winter and summer temperatures alone, and in combination, at a tundra field site at the Eight Mile Lake watershed near Healy, Alaska. The objective of this experimental warming was to significantly raise air and deep soil temperatures and increase the depth of thaw beyond that of previous warming experiments. Detecting the loss and fate of the old permafrost C pool remains a major challenge. Because soil C has been accumulating in these ecosystems over the past 10,000 years, there is a strong difference between the radiocarbon isotopic composition of C deep in the soil profile and permafrost compared to that near the soil surface. This large range of isotopic variability is unique to radiocarbon and provides a valuable and sensitive fingerprint for detecting the loss of old soil C as permafrost thaws.
During Project DE-FE0007528, CARE (Carbon Absorber Retrofit Equipment), Neumann Systems Group (NSG) designed, installed and tested a 0.5MW NeuStream® carbon dioxide (CO 2 ) capture system using the patented NeuStream® absorber equipment and concentrated (6 molal) piperazine (PZ) as the solvent at Colorado Springs Utilities’ (CSU’s) Martin Drake pulverized coal (PC) power plant. The 36 month project included design, build and test phases. The 0.5MW NeuStream® CO 2 capture system was successfully tested on flue gas from both coal and natural gas combustion sources and was shown to meet project objectives. Ninety percent CO 2 removal was achieved with greater than 95% CO 2 product purity. The absorbers tested support a 90% reduction in absorber volume compared to packed towers and with an absorber parasitic power of less than 1% when configured for operation with a 550MW coal plant. The preliminary techno-economic analysis (TEA) performed by the Energy and Environmental Research Center (EERC) predicted an over-the-fence cost of $25.73/tonne of CO 2 captured from a sub-critical PC plant.
Sandia National Laboratories operates the Scaled Wind Farm Technology Facility (SWiFT) on behalf of the Department of Energy Wind and Water Power Technologies Office. An analysis was performed to evaluate the hazards associated with debris thrown from one of SWiFT’s operating wind turbines, assuming a catastrophic failure. A Monte Carlo analysis was conducted to assess the complex variable space associated with debris throw hazards that included wind speed, wind direction, azimuth and pitch angles of the blade, and percentage of the blade that was separated. In addition, a set of high fidelity explicit dynamic finite element simulations were performed to determine the threshold impact energy envelope for the turbine control building located on-site. Assuming that all of the layered, independent, passive and active engineered safety systems and administrative procedures failed (a 100% failure rate of the safety systems), the likelihood of the control building being struck was calculated to be less than 5/10,000 and ballistic simulations showed that the control building would not provide passive protection for the majority of impact scenarios. Although options exist to improve the ballistic resistance of the control building, the recommendation is not to pursue them because there is a low probability of strike and there is an equal likelihood personnel could be located at similar distances in other areas of the SWiFT facility which are not passively protected, while the turbines are operating. A fenced exclusion area has been created around the turbines which restricts access to the boundary of the 1/100 strike probability. The overall recommendation is to neither relocate nor improve passive protection of the control building as the turbine safety systems have been improved to have no less than two independent, redundant, high quality engineered safety systems. Considering this, in combination with a control building strike probability of less than 5/10,000, the overall probability of turbine debris striking the control building is less than 1/1,000,000.
Sampling Period: June 14–17 and July 7, 2016. Water samples were collected from 36 locations at New Rifle and Old Rifle, Colorado, Disposal/Processing Sites. Planned monitoring locations are shown in Attachment 1, Sampling and Analysis Work Order. Duplicate samples were collected from New Rifle locations 0216 and 0855, and Old Rifle location 0655. One equipment blank was collected after decontamination of non-dedicated equipment used to collect one surface water sample. See Attachment 2, Trip Report for additional details. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated, http://energy.gov/lm/downloads/sampling-and- analysis-plan-us-department-energy-office-legacy-management-sites). New Rifle Site Samples were collected at the New Rifle site from 16 monitoring wells and 7 surface locations in compliance with the December 2008 Groundwater Compliance Action Plan [GCAP] for the New Rifle, Colorado, Processing Site (LMS/RFN/S01920). Monitoring well 0216 could not be sampled in June because it was surrounded by standing water due to the high river stage from spring runoff, it was later sampled in July. Monitoring well 0635 and surface location 0322 could not be sampled because access through the elk fence along Interstate 70 has not been completed at this time. Old Rifle Site Samples were collected at the Old Rifle site from eight monitoring wells and five surface locations in compliance with the December 2001 Ground Water Compliance Action Plan for the Old Rifle, Colorado, UMTRA Project Site (GJ0-2000-177-TAR).
This Closure Report (CR) presents information supporting the closure of Corrective Action Unit (CAU) 573: Alpha Contaminated Sites, Nevada National Security Site, Nevada. CAU 573 comprises the two corrective action sites (CASs): 05-23-02-GMX Alpha Contaminated Are-Closure in Place and 05-45-01-Atmospheric Test Site - Hamilton- Clean Closure. The purpose of this CR is to provide justification and documentation supporting the recommendation that no further corrective action is needed for CAU 573 based on the implementation of the corrective actions. Corrective action activities were performed at Hamilton from May 25 through June 30, 2016; and at GMX from May 25 to October 27, 2016, as set forth in the Corrective Action Decision Document (CADD)/Corrective Action Plan (CAP) for Corrective Action Unit 573: Alpha Contaminated Sites; and in accordance with the Soils Activity Quality Assurance Plan, which establishes requirements, technical planning, and general quality practices. Verification sample results were evaluated against data quality objective criteria developed by stakeholders that included representatives from the Nevada Division of Environmental Protection and the DOE, National Nuclear Security Administration Nevada Field Office (NNSA/NFO) during the corrective action alternative (CAA) meeting held on November 24, 2015. Radiological doses exceeding the final action level were assumed to be present within the high contamination areas associated with CAS 05-23-02, thus requiring corrective action. It was also assumed that radionuclides were present at levels that require corrective action within the soil/debris pile associated with CAS 05-45-01. During the CAU 573 CAA meeting, the CAA of closure in place with a use restriction (UR) was selected by the stakeholders as the preferred corrective action of the high contamination areas at CAS 05-23-02 (GMX), which contain high levels of removable contamination; and the CAA of clean closure was selected by the stakeholders as preferred corrective action for the debris pile at CAS 05-45-01 (Hamilton). The closure in place was accomplished by posting signs containing a warning label on the existing contamination area fence line; and recording the FFACO UR and administrative UR in the FFACO database, the NNSA/NFO CAU/CAS files, and the management and operating contractor Geographic Information Systems. The clean closure was accomplished by excavating the soil/debris pile, disposing of the contents at the Area 5 Radioactive Waste Management Complex, and collecting verification samples. The corrective actions were implemented as stipulated in the CADD/CAP, and verification sample results confirm that the criteria for the completion of corrective actions have been met. Based on the implementation of these corrective actions, NNSA/NFO provides the following recommendations: No further corrective actions are necessary for CAU 573; The Nevada Division of Environmental Protection should issue a Notice of Completion to NNSA/NFO for closure of CAU 573; CAU 573 should be moved from Appendix III to Appendix IV of the FFACO.
Water samples were collected from 36 locations at New Rifle and Old Rifle, Colorado, Processing Sites. Duplicate samples were collected from New Rifle locations 0659 and 0855, and Old Rifle location 0304. One equipment blank was collected after decontamination of non-dedicated equipment used to collect one surface water sample. Sampling and analyses were conducted as specified in the Sampling and Analysis Plan for U.S. Department of Energy Office of Legacy Management Sites (LMS/PRO/S04351, continually updated). New Rifle Site Samples were collected at the New Rifle site from 16 monitoring wells and 7 surface locations in compliance with the December 2008 Groundwater Compliance Action Plan [GCAP] for the New Rifle, Colorado, Processing Site (LMS/RFN/S01920), with one exception: New Rifle location 0635 could not be sampled because it was inaccessible; a fence installed by the Colorado Department of Transportation prevents access to this location. DOE is currently negotiating access with the Colorado Department of Transportation. Analytes measured at the New Rifle site included contaminants of concern (COCs) (arsenic, molybdenum, nitrate + nitrite as nitrogen, selenium, uranium, and vanadium) ammonia as nitrogen, major cations, and major anions. Field measurements of total alkalinity, oxidation- reduction potential, pH, specific conductance, turbidity, and temperature were made at each location, and the water level was measured at each sampled well. A proposed alternate concentration limit (ACL) for vanadium of 50 milligrams per liter (mg/L), specific to the compliance (POC) wells (RFN-0217, -0659, -0664, and -0669) is included in the New Rifle GCAP. Vanadium concentrations in the POC wells were below the proposed ACL as shown in the time-concentration graphs in the Data Presentation section (Attachment 2). Time-concentration graphs from all other locations sampled are also included in Attachment 2. Sampling location RFN-0195 was misidentified for the June/August 2014 and November 2014 sampling events. (Well RFN-0609 was inadvertently sampled instead of RFN-0195 in 2014.) The results for RFN-0195 have been corrected, and are included in associated time-concentration graphs for this location. Recent results for RFN-0195 are consistent with established trends with the possible exception of vanadium. The most recent result for vanadium showed an increase over recent values. Vanadium concentrations at RFN-0195 and other locations will continue to be evaluated in the future to determine the potential for deviations from established trends. The surface water locations were sampled to monitor the impact of groundwater discharge. COC concentrations at Colorado River surface water locations RFN-0324 and RFN-0326, downgradient of the site, remained low and were consistent with historical results, as shown in the time-concentration graphs. COC concentrations did not indicate there are any impacts related to groundwater discharge to the river. In many cases, elevated COC concentrations at the New Rifle site pond locations were observed, as shown in the time-versus concentration graphs. As noted in the GCAP, this indicates impacts from groundwater discharge to the ponds. Old Rifle Site Samples were collected at the Old Rifle site from eight monitoring wells and five surface locations in compliance with the December 2001 Groundwater Compliance Action Plan for the Old Rifle, Colorado, UMTRA Project Site (GJ0-2000-177-TAR). Analytes measured at the Old Rifle site included COCs (selenium, uranium, and vanadium), major cations, and major anions. Field measurements of total alkalinity, oxidation-reduction potential, pH, specific conductance, turbidity, temperature, were made at each location, and the water level was measured at each sampled well. The monitoring strategy described in the GCAP is designed to determine progress of the natural flushing process in meeting compliance standards for site COCs. Standards for selenium and vanadium are the proposed ACLs of0.05 mg/L and 1.0 mg/L, respectively. For uranium the cleanup goal is the UMTRA standard of 0.044 mg/L or background, whichever is higher. As shown in the time concentration graphs, the uranium concentration exceeds the cleanup goal at groundwater monitoring locations RF0-0304, -0305, -0310, -0655, and -0656. The surface water locations were sampled to monitor the impact of groundwater discharge at Colorado River surface water locations adjacent to (RF0-0396) and downgradient of the site (RF0-0741). COC concentrations remain low and consistent with historical concentrations as shown in the time-concentration graphs (Attachment 2), which indicate no impacts from groundwater discharge to the river.
Permafrost Thawing and Vegetation Change Effects on Cryoturbation Rates and C and CH4 Dynamics Permafrost soils cover 8.6% of the Earth land area but contain 50% of the global soil organic carbon (SOC) pool, 20-25% of which may be stored in the upper 30 cm, making it highly vulnerable to changes in climate. Predicted warming in northern latitudes may lead to strong forcing feedbacks on the climate system. It has been shown that the C content in the active layer of cryoturbated soils can be roughly 60% higher than in non-cryoturbated ones. However other cryogenic processes can affect the Arctic soil C pool at shorter time scales. For instance, warming may lead to increases winter precipitation resulting in a deeper snow cover with consequent thermal insulation of Arctic soils. Warmer soils may elicit summer and winter decomposition rates decreasing the SOC pool. We developed multi isotope methods to measure the soil carbon effects of snow pack accumulation on Arctic SOC dynamics in a moist acidic tundra by exposing soils to experimental accumulated snow pack (using fence experiments, Toolik Lake) in order to increase soil thermal insulation. We found that carbon dynamics were not linear and transient. At the beginning of the experiment C was lost in great quantities but they were partly recovered after about two decades. Snow cover also slows the C lost from permafrost thaw but increases CH4 emissions and heterotrophic respiration. Carbon was redistributed along the soil profile and moisture rather than temperature appeared to be the factor controlling decomposability.
Environmental monitoring data are collected at and around the Area 3 and Area 5 Radioactive Waste Management Sites (RWMSs) within the Nevada National Security Site (NNSS). These data include direct radiation exposure, as well as radiation from the air, groundwater, meteorology, and vadose zone. This report summarizes the 2015 environmental data to provide an overall evaluation of RWMS performance and to support environmental compliance and performance assessment (PA) activities. Some of these data (e.g., radiation exposure, air, and groundwater) are presented in other reports developed by National Security Technologies, LLC. Direct radiation monitoring data indicate exposure levels at the RWMSs are within the range of background levels measured at the NNSS. Slightly elevated exposure levels outside the Area 3 RWMS are attributed to nearby historical aboveground nuclear weapons tests. Air monitoring data show that tritium concentrations in water vapor and americium and plutonium concentrations in air particles are below Derived Concentration Standards for these radionuclides. Groundwater monitoring data indicate the groundwater in the uppermost aquifer beneath the Area 5 RWMS is not impacted by RWMS operations. Results of groundwater analysis from wells around the Area 5 RWMS were all below established investigation levels. Leachate samples collected from the leachate collection system at the mixed low-level waste cell were below established contaminant regulatory limits. During 2015, precipitation at the Area 3 RWMS was 0.9% above average, and precipitation at the Area 5 RWMS was 25% above average. Water balance measurements indicate that evapotranspiration from the vegetated weighing lysimeter dries the soil and prevents downward percolation of precipitation more effectively than evaporation as measured from the bare-soil weighing lysimeter. The 1.8 inches of precipitation in September reached the lowest sensors at 180 cm on the Cell 5S and 5N covers, however the sensors on the floor do not indicate any signs of the precipitation percolating thru the waste to the floor. Moisture from precipitation did not percolate below 150 centimeters (cm) (5 feet [ft]) in the vegetated final cover on the U-3ax/bl disposal unit at the Area 3 RWMS. A second remedial revegetation trial was done on the southern portion of the North Cover. In March 2015 it was determined that germination occurred on both the mulched and non-mulched treatments that were irrigated, but that no germination occurred on the non-irrigated treatments. By June the seedlings observed in March were gone, possibly grazed by rabbits which were observed inside the rabbit-proof fence. In August the entire area was sprayed with the herbicide glyphosate in an attempt to minimize weed seed production. During 2015, there was no drainage through 2.4 meters (8 ft) of soil as indicated from the Area 3 drainage lysimeters that received only natural precipitation. Thirty-one percent of the applied precipitation and irrigation drained from the bare-soil drainage lysimeter, which received 3 times the natural precipitation. All 2015 monitoring data indicate that the Area 3 and Area 5 RWMSs are performing within expectations of the model and parameter assumptions for the facilities’ PAs.