Selecting Species for Marine Assessment of Radionuclides Around Amchitka: Planning for Diverse Goals and Interests

Considerable attention has been devoted to selecting bioindicator species as part of monitoring programs for exposure and effects from contaminants in the environment. Yet the rationale for selection of bioindicators is often literature-based, rather than developed with a firm site-specific base of data on contaminant levels in a diverse range of organisms at different trophic levels in the same ecosystem. We suggest that this latter step is an important phase in the environmental assessment process that is often missing. In this paper we address the problem of how to select a wide range of species representing different trophic levels that serve as a basis for selecting a few species suitable as bioindicators. We illustrate this with our assessment of radionuclides on Amchitka Island, Alaska. We propose a multi-stage process for arriving at the list of available species that includes review of literature, review by experts experienced in the area, review by interested and affected parties, selection of trophic levels or groups for analysis, arraying of possible species, and selection of species within each trophic level group for sample collection. We first had to identify all likely species, then narrow our focus to those we could collect and analyze. In all cases, review includes suggestions for possible target species with justifications. While this method increases the up-front costs of developing bioindicators for an ecosystem, it has the advantage of providing information for selection of species that will be most informative in the long run, including those that are the best bioaccumulators, thus providing the earliest warning of any potential environmental consequences. Further, the recognition that a range of stakeholder's needs and interests should be included increases the utility for public-policy makers, and the potential for continued usage to establish long-term trends.     

Geographic Variability in Radon Exhalation at a Rehabilitated Uranium Mine in the Northern Territory, Australia

In this study, dry season radon flux densities and radon fluxes have been determined at the rehabilitated Nabarlek uranium mine in northern Australia using conventional charcoal canisters. Environmental background levels amounted to 31± 15 milli Becquerel per m² per second (mBq m⁻² s⁻¹). Radon flux densities within the fenced rehabilitated mine area showed large variations with a maximum of 6500 mBq m⁻² s⁻¹ at an area south of the former pit characterised by a disequilibrium between ²²⁶Ra and ²³⁸U. Radon flux densities were also high above the areas of the former pit (mean 971 mBq m⁻² s⁻¹) and waste rock dump (mean 335 mBq m⁻² s⁻¹). The lower limit for the total pre-mining radon flux from the fenced area (140 ha) was estimated to 214 kBq s⁻¹, post-mining radon flux amounted to 174 kBq s⁻¹.Our study highlights that the results of radon flux studies are vitally dependant on the selection of individual survey points. We suggest the use of a randomised system for both the selection of survey points and the placement of charcoal canisters at each survey point, to avoid over estimation of radon flux densities. It is also important to emphasize the significance of having reliable pre-mining radiological data available to assess the success of rehabilitation of a uranium mine site.2006 Springer. The Australian Government's right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged.     

Inorganic nitrogen transformations in the treatment of landfill leachate with a high ammonium load: A case study

The inorganic nitrogen transformations occurring at a municipal waste leachate treatment facility were investigated. The treatment facility consisted of a collection well and an artificial wetland between two aeration ponds. The first aeration pond showed a decrease in ammonium (from 3480 (± 120) to 630(± 90) mg ⋅ L⁻¹), a reduction in inorganic nitrogen load (3480 to 1680 mg N ⋅ L⁻¹), and an accumulation of nitrite (< 1.3 mg-N ⋅ L⁻¹ in the collection well, to 1030 mg-N ⋅ L⁻¹). Incomplete ammonium oxidation was presumably the result of the low concentration of carbonate alkalinity (∼2 mg ⋅ L⁻¹), which may cause a limitation in the ammonium oxidation rate of nitrifiers. Low carbonate alkalinity levels may have been the result of stripping of CO₂ from the first aeration pond at the high aeration rates and low pH. Various chemodenitrification mechanisms are discussed as the reason for the reduction in the inorganic nitrogen load, including; the reduction of nitrite by iron (II) (producing various forms of gaseous nitrogen); and reactions involving nitrous acid. It is suggested that the accumulation of nitrite may be the result of inhibition of nitrite oxidizers by nitrous acid and low temperatures. Relative to the first aeration pond, the speciation and concentration of inorganic nitrogen was stable in the wetlands and 2nd aeration pond. The limited denitrification in the wetlands most probably occurred due to low concentrations of organic carbon, and short retention times.     

Responses of Physical, Chemical, and Biological Indicators of Water Quality to a Gradient of Agricultural Land Use in the Yakima River Basin, Washington

The condition of 25 stream sites in the Yakima River Basin, Washington, were assessed by the U.S. Geological Survey's National Water-Quality Assessment Program. Multimetric condition indices were developed and used to rank sites on the basis of physical, chemical, and biological characteristics. These indices showed that sites in the Cascades and Eastern Cascades ecoregions were largely unimpaired. In contrast, all but two sites in the Columbia Basin ecoregion were impaired, some severely. Agriculture (nutrients and pesticides) was the primary factor associated with impairment and all impaired sites were characterized by multiple indicators of impairment. All indices of biological condition (fish, invertebrates, and algae) declined as agricultural intensity increased. The response exhibited by invertebrates and algae suggested a threshold response with conditions declining precipitously at relatively low levels of agricultural intensity and little response at moderate to high levels of agricultural intensity. This pattern of response suggests that the success of mitigation will vary depending upon where on the response curve the mitigation is undertaken. Because the form of the community condition response is critical to effective water-quality management, the National Water-Quality Assessment Program is conducting studies to examine the response of biota to gradients of land-use intensity and the relevance of these responses to water-quality management. These land-use gradient pilot studies will be conducted in several urban areas starting in 1999.     

Overview of Contemporary Issues of Forest Research and Management in China

With 207 million ha of forest covering 22% of its land area, China ranks fifth in the world in forest area. Rapid economic growth, climate change, and forest disturbances pose new, complex challenges for forest research and management. Progress in meeting these challenges is relevant beyond China, because China’s forests represent 34% of Asia’s forests and 5% of the worlds’ forests. To provide a broader understanding of these management challenges and of research and policies that address them, we organized this special issue on contemporary forest research and management issues in China. At the national level, papers review major forest types and the evolution of sustainable forestry, the development of China’s forest-certification efforts, the establishment of a forest inventory system, and achievements and challenges in insect pest control in China. Papers focused on Northern China address historical, social, and political factors that have shaped the region’s forests; the use of forest landscape models to assess how forest management can achieve multiple objectives; and analysis and modeling of fuels and fire behavior. Papers addressing Central and South China describe the “Grain for Green” program, which converts low productivity cropland to grassland and woodland to address erosion and soil carbon sequestration; the potential effects of climate change on CO₂ efflux and soil respiration; and relationships between climate and net primary productivity. China shares many forest management and research issues with other countries, but in other cases China’s capacity to respond to forest management challenges is unique and bears watching by the rest of the world.     

Evaluating the effects of alternative forest management plans under various physiographic settings using historical records as a reference

Using historical General Land Office record as a reference, this study employed a landscape-scale disturbance and succession model to estimate the future cumulative effects of six alternative management plans on the tree species composition for various physiographic settings for the Mark Twain National Forest in Missouri. The results indicate that over a 200-year horizon, the relative abundance of black oak and pine species groups will decrease and the relative abundance of the white oak species group will increase, regardless of management strategy. General Land Office witness tree records provide a measure of tree species composition in the period from 1800 to 1850, prior to the large-scale influx of European settlers. Compared to the tree species composition described in the General Land Office records, the six contemporary management alternatives considered all would lead to a lower abundance of pine species, a higher abundance of red/black oak species, and a slightly higher abundance of white oak species after 200 years. Impacts of management on tree species composition varied with physiographic settings. The projected relative abundance of pine differed significantly across the five physiographic classes over the first 40 years of the simulation. In the medium term (simulation years 41-100) the projected relative pine abundance differed significantly among only four physiographic classes. In the long term (simulation years 100-200) the projected relative pine abundance differed for only one physiographic class. In contrast, differences among physiographic classes in the relative abundance of black oaks and white oaks increased over time. In general, the expected long-term differences in relative tree species abundance among six proposed alternative management plans are small compared to shifts in tree species composition that have occurred from 1850 to the present.     

Factors Affecting Stream Nutrient Loads: A Synthesis of Regional SPARROW Model Results for the Continental United States1

Preston, Stephen D., Richard B. Alexander, Gregory E. Schwarz, and Charles G. Crawford, 2011. Factors Affecting Stream Nutrient Loads: A Synthesis of Regional SPARROW Model Results for the Continental United States. Journal of the American Water Resources Association (JAWRA) 47(5):891‐915. DOI: 10.1111/j.1752‐1688.2011.00577.x Abstract: We compared the results of 12 recently calibrated regional SPARROW (SPAtially Referenced Regressions On Watershed attributes) models covering most of the continental United States to evaluate the consistency and regional differences in factors affecting stream nutrient loads. The models – 6 for total nitrogen and 6 for total phosphorus – all provide similar levels of prediction accuracy, but those for major river basins in the eastern half of the country were somewhat more accurate. The models simulate long‐term mean annual stream nutrient loads as a function of a wide range of known sources and climatic (precipitation, temperature), landscape (e.g., soils, geology), and aquatic factors affecting nutrient fate and transport. The results confirm the dominant effects of urban and agricultural sources on stream nutrient loads nationally and regionally, but reveal considerable spatial variability in the specific types of sources that control water quality. These include regional differences in the relative importance of different types of urban (municipal and industrial point vs. diffuse urban runoff) and agriculture (crop cultivation vs. animal waste) sources, as well as the effects of atmospheric deposition, mining, and background (e.g., soil phosphorus) sources on stream nutrients. Overall, we found that the SPARROW model results provide a consistent set of information for identifying the major sources and environmental factors affecting nutrient fate and transport in United States watersheds at regional and subregional scales.     

Millennial‐Length Records of Streamflow From Three Major Upper Colorado River Tributaries1

Gray, Stephen T., Jeffrey J. Lukas, and Connie A. Woodhouse, 2011. Millennial‐Length Records of Streamflow From Three Major Upper Colorado River Tributaries. Journal of the American Water Resources Association (JAWRA) 47(4):702‐712. DOI: 10.1111/j.1752‐1688.2011.00535.x Abstract: Drought, climate change, and shifting consumptive use are prompting a widespread reassessment of water availability in the Upper Colorado River basin. Here, we present millennial‐length records of water year (October‐September) streamflow for key Upper Colorado tributaries: the White, Yampa, and Little Snake Rivers. Based on tree rings, these records represent the first paleohydrological reconstructions from these subbasins to overlap with a series of Medieval droughts (∼ad 800 to 1300). The reconstructions show marked interannual variability imbedded in nonstationary behavior over decadal to multidecadal time scales. These reconstructions suggest that, even in a millennial context, gaged flows from a handful of years (e.g., 1977 and 2002) were extremely dry. However, droughts of much greater duration and magnitude than any in the instrumental record were regular features prior to 1900. Likewise these reconstructions point to the unusual wetness of the gage period, and the potential for recent observations to paint an overly optimistic picture of regional water supplies. The future of the Upper Colorado River will be determined by a combination of inherent hydroclimatic variability and a broad range of human‐induced changes. It is then essential that regional water managers, water users, and policy makers alike consider a broader range of hydroclimatic scenarios than is offered by the gage record alone.     

Relationships between water mass characteristics and estimates of fish population abundance from trawl surveys

The Canadian Department of Fisheries and Oceans conducts annual bottom trawl surveys to monitor changes in the abundance of the major commercially important groundfish populations. Some of these surveys have been in operation for almost 20 yr. The estimates from these surveys often indicate rapid changes in abundance over time beyond that expected from the population dynamics of the fish. Much of this interannual change has been interpreted as variation, the magnitude of which has often made it difficult to measure anything but the most severe effects of fishing, pollution or any other intervention on the population. Recent studies have shown that some of this variation may be attributed to changes in catchability of fish due to the effects of environmental variables on fish distribution. Annual changes in abundance as estimated from such field surveys may be confounded by changes in catchability due to annual changes in environmental conditions. In this study, trawl catches of age 4 Atlantic cod (Gadus morhua) from surveys conducted during March 1979–1988 were compared with concurrent measurements of bottom salinity, temperature and depth. Large catches of age 4 cod are more likely to occur in water characterized as the intermediate cold layer defined by salinities of 32–33.5 and temperatures<5°C. This relationship also appears to be modified by depth. We further show that internnual changes in the estimated abundance from the surveys were, in a number of cases, coincident with changes in the proportion of the bottom water composed of the intermediate cold water layer. The implications that these patterns may have on interpreting trends in the estimates of abundance from trawl surveys are discussed.