Rodents as receptor species at a tritium disposal site

New methods are being employed on the Department of Energy's Savannah River Site to deal with the disposal of tritium, including the irrigation of a hardwood/pine forest with tritiated water from an intercepted contaminant plume to reduce concentrations of tritium outcropping into Fourmile Branch, a tributary of the Savannah River. The use of this system has proven to be an effective means of tritium disposal. To evaluate the impact of this activity on terrestrial biota, rodent species were captured on the tritium disposal site and a control site during two trapping seasons in order to assess tritium exposure resulting from the forest irrigation. Control site mice had background levels of tritium, 0.02 Bq/mL, with disposal site mice having significantly higher tritium concentrations, mean=34.86 Bq/mL. Whole body tritium concentrations of the mice captured at the disposal site were positively correlated with tritium application and negatively correlated with precipitation at the site.     

Spatial and time variations of radon-222 concentration in the atmosphere of a dead-end horizontal tunnel

The concentration of radon-222 has been monitored since 1995 in the atmosphere of a 2 m transverse dimension, 128 m long, dead-end horizontal tunnel located in the French Alps, at an altitude of 1600 m. Most of the time, the radon concentration is stable, with an average value ranging from 200 Bq m(-3) near the entrance to about 1000 Bq m(-3) in the most confined section, with an equilibrium factor between radon and its short-lived decay products varying from 0.61 to 0.78. However, radon bursts are repeatedly observed, with amplitudes reaching up to 36 x 10(3) Bq m(-3) and durations varying from one to several weeks, with similar spatial variations along the tunnel as the background concentration. These spatial variations are qualitatively interpreted in terms of natural ventilation. Comparing the radon background concentration with the measured radon exhalation flux at the wall yields an estimate of 8+/-2 x 10(-6) s(-1) (0.03+/-0.007 h(-1)) for the ventilation rate. The hypothesis that the bursts could be due to transient changes in ventilation can be ruled out. Thus, the bursts are the results of transient increased radon exhalation at the walls, that could be due to meteorological effects or possibly combined hydrological and mechanical forcing associated with the water level variations of the nearby Roselend reservoir lake. Such studies are of interest for radiation protection in poorly ventilated underground settings, and, ultimately, for a better understanding of radon exhalation associated with tectonic or volcanic processes.     

Determination of the organic aerosol mass to organic carbon ratio in IMPROVE samples

The ratio of organic mass (OM) to organic carbon (OC) in PM(2.5) aerosols at US national parks in the IMPROVE network was estimated experimentally from solvent extraction of sample filters and from the difference between PM(2.5) mass and chemical constituents other than OC (mass balance) in IMPROVE samples from 1988 to 2003. Archived IMPROVE filters from five IMPROVE sites were extracted with dichloromethane (DCM), acetone and water. The extract residues were weighed to determine OM and analyzed for OC by thermal optical reflectance (TOR). On average, successive extracts of DCM, acetone, and water contained 64%, 21%, and 15%, respectively, of the extractable OC, respectively. On average, the non-blank-corrected recovery of the OC initially measured in these samples by TOR was 115+/-42%. OM/OC ratios from the combined DCM and acetone extracts averaged 1.92 and ranged from 1.58 at Indian Gardens, AZ in the Grand Canyon to 2.58 at Mount Rainier, WA. The average OM/OC ratio determined by mass balance was 2.07 across the IMPROVE network. The sensitivity of this ratio to assumptions concerning sulfate neutralization, water uptake by hygroscopic species, soil mass, and nitrate volatilization were evaluated. These results suggest that the value of 1.4 for the OM/OC ratio commonly used for mass and light extinction reconstruction in IMPROVE is too low.     

Linking Riparian Dynamics and Groundwater: An Ecohydrologic Approach to Modeling Groundwater and Riparian Vegetation

The growing use of global freshwater supplies is increasing the need for improved modeling of the linkage between groundwater and riparian vegetation. Traditional groundwater models such as MODFLOW have been used to predict changes in regional groundwater levels, and thus riparian vegetation potential attributable to anthropogenic water use. This article describes an approach that improves on these modeling techniques through several innovations. First, evapotranspiration from riparian/wetland systems is modeled in a manner that more realistically reflects plant ecophysiology and vegetation complexity. In the authors’ model programs (RIP-ET and PRE-RIP-ET), the single, monotonically increasing evapotranspiration flux curve in traditional groundwater models is replaced with a set of ecophysiologically based curves, one for each plant functional group present. For each group, the curve simulates transpiration declines that occur both as water levels decline below rooting depths and as waters rise to levels that produce anoxic soil conditions. Accuracy is further improved by more effective spatial handling of vegetation distribution, which allows modeling of surface elevation and depth to water for multiple vegetation types within each large model cell. The use of RIP-ET in groundwater models can improve the accuracy of basin scale estimates of riparian evapotranspiration rates, riparian vegetation water requirements, and water budgets. Two case studies are used to demonstrate that RIP-ET produces significantly different evapotranspiration estimates than the traditional method. When combined with vegetation mapping and a supporting program (RIP-GIS), RIP-ET also enables predictions of riparian vegetation response to water use and development scenarios. The RIP-GIS program links the head distribution from MODFLOW with surface digital elevation models, producing moderate- to high-resolution depth-to-groundwater maps. Together with information on plant rooting depths, these can be used to predict vegetation response to water allocation decisions. The different evapotranspiration outcomes produced by traditional and RIP-ET approaches affect resulting interpretations of hydro-vegetation dynamics, including the effects of groundwater pumping stress on existing habitats, and thus affect subsequent policy decisions.     

Tree Structure and Diversity in Human-Impacted Littoral Forests, Madagascar

This research surveyed human-impacted littoral forests in southeastern Madagascar to determine (i) how forest structural features, indicative of human impact, are related to total, utilitarian, and endemic tree diversity; (ii) the distribution, abundance, and demographics of tree species groups (i.e., total, useful, endemic) across the landscape; and (iii) the amount of basal area available per human use category. We also use these data to consider issues of sustainable use and how human impact may influence littoral forest tree community composition across the landscape. Within 22 transects of 400 m² each, we recorded a total of 135 tree species and 2155 individuals. Seventy-nine species (58%) were utilitarian and 56 (42%) were nonutilitarian species. Of the 2155 individuals, 1827 (84%) trees were utilitarian species. We recorded 23 endemic species (17% of the total species) and 17 (74%) of these were utilitarian species. Basal area was significantly correlated with Shannon Weiner Index values for total (r = 0.64, P < 0.01), utilitarian (r = 0.58, P < 0.01), and endemic tree diversity (r = 0.85, P < 0.01). Basal area was significantly correlated with the Simpson’s index values for the endemic species (r = 0.74, P < 0.01). These correlations suggest that endemic tree species, of high global conservation value, may be the species group most influenced by changes in forest structure. Utilitarian species constituted 84% of the total basal area. The use category contributing the highest amount of basal area to the landscape was firewood. The results presented herein demonstrate that the landscape of southeastern Madagascar, commonly perceived as degraded, retains high value for both global conservation purposes and for local livelihoods. Thus, valuable opportunities may exist for developing conservation incentives that leverage both global and local conservation needs.     

Levels of antifoulant Irgarol 1051 in the Conwy Marina, North Wales

Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an antifouling agent used in paint formulations that are applied to the hulls of ships. A survey was carried out at Conwy Marina in North Wales to determine the levels of the herbicide over a period of three months. Liquid/liquid extraction was used to concentrate the analyte for quantitative analysis using gas chromatography/mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. The concentrations of Irgarol 1051 in Conwy marina ranged from 7 to 543 ng/l, similar to the levels found in many other marinas, estuaries and ports in England, although much lower than those in C?te d'Azur, France. The concentrations of Irgarol 1051 were not found to be influenced by salinity, pH or temperature, although there is a strong correlation between the average concentrations of Irgarol 1051 and the density of boating activity. At the levels found in the marina, it is possible that non-target photosynthetic inhibition could occur.     

Fate of urine nitrogen in three soils throughout a grazing season

The fate of 15N-labeled cattle (Bos taurus) urine (52 g N m(-2)), applied to a 0.4-m2 surface area on three dates between May and October to three different pasture soils, was studied using 2-m2 lysimeters. Over a period of two years, the sward recovered most of the 15N, but the amount recovered decreased with application date (62% in spring to 17% in fall). However, N uptake by ryegrass (Lolium perenne L.) in Year 2 showed that some nitrogen came from the previous year's urine application. The largest leaching losses of urine N resulted from the late application date. These losses mainly occurred during the first winter despite the small amount of water drainage. Soil type largely determined 15N losses. The granitic Brunisol was the most freely draining and had the greatest leaching (up to 35% recovery of urinary N). In contrast, leaching in the silty loam Neoluvisol remained under 4% of 15N applied. The Calcosol appeared to be susceptible to all kinds of N losses with intermediate unaccounted-for N pool and leaching fractions and lesser utilization of urinary N by grass. Immobilization in soil organic matter, roots and litter, and stubble pools were not markedly influenced by the date of application or soil type. They amounted to 25 to 33, 2, and 2% of N applied as urine, respectively. In these climatic conditions with moderate drainage, leaching of water poor in quality for nitrate only occurred for late-season grazing or on the granitic Brunisol, which was very vulnerable to leaching.     

Analysis of Scavengers’ Activities and Recycling in Some Cities of Nigeria

The state of solid waste recycling by scavengers in Onitsha, a heavily commercial city in Anambra State, and some other urban areas such as Nsukka, Enugu, and Port Harcourt was analyzed. Data were obtained through interviews of scavengers who deal with recyclables. Although the activities of scavengers are sub-optimal, they can have a great impact on Nigerian economy with respect to resource conservation, creation of job opportunities, and reduction of the magnitude of waste disposal problems. A cost analysis is presented to compare the different forms of recycling utilized by municipal solid waste management. It is shown that a well-planned recycling program with recycling and composting would result in 18.6% savings in waste management costs and 57.7% in landfill avoidance costs. However, if the compost materials are not recycled, the corresponding savings in cost become 8.6% and 28.6%, respectively. The option with the lowest cost involves encouraging individual households to separate at the source their recyclables, which are bought by scavengers. This results in 78.0% savings in waste management cost and 79.5% landfill avoidance cost. A low-cost approach aimed at the integration of scavenging activities into conventional solid waste management is presented.     

The relief operation in puno district, peru, after the 1986 floods of lake titicaca

The 1985-86 rainy season in Peru was disastrous due to very high precipitation. Because of the unusual level of floods in the Lake Titicaca area and the increasing number of affected people, the Peruvian Government established an emergency relief plan and appealed for international aid. At that time the situation was already very critical. The lack of preparedness made the implementation of the relief operation difficult. Our paper describes the intervention of a French N.G.O. (Médecins Sans Trontières), requested by the Peruvian authorities. The early phase of the relief programme and its methodology are described. Problems within this relief programme and the further long-term development action that should be undertaken are discussed.
Au Pérou, la saison des pluies 85–86 a été catastrophique par l'importance des précipitations. Au cours des premiers mois de l'année 1986, devant l'ampleur inhabituelle des inondations dans la région du lac Titicaca et le nombre sans cesse croissant de sinistrés, le gouvernement pbruvien décide de mettre en route un plan national de secours d'urgence enfaisant appel à l'aide internationale. Mais la réponse est déjá tardive et le manque de mesures préventives fait que l'organisation des secours se heurte à un grand nombre de difficultés. Notre étude se situe dans le cadre de l'intervention d'une organisation non gouvernementale européenne, sollicitée par le gouvernement péruvien pour une collaboration dans la phase des premiers secours à cette population. Les problémes posés lors de cette opération et la suite à donner à l'assistance a moyen et a long terme sont discutés.     

High precision during food recruitment of experienced (reactivated) foragers in the stingless bee<Emphasis Type="Italic"> Scaptotrigona mexicana</Emphasis> (Apidae,Meliponini)

Several studies have examined the existence of recruitment communication mechanisms in stingless bees. However, the spatial accuracy of location-specific recruitment has not been examined. Moreover, the location-specific recruitment of reactivated foragers, i.e., foragers that have previously experienced the same food source at a different location and time, has not been explicitly examined. However, such foragers may also play a significant role in colony foraging, particularly in small colonies. Here we report that reactivated Scaptotrigona mexicana foragers can recruit with high precision to a specific food location. The recruitment precision of reactivated foragers was evaluated by placing control feeders to the left and the right of the training feeder (direction-precision tests) and between the nest and the training feeder and beyond it (distance-precision tests). Reactivated foragers arrived at the correct location with high precision: 98.44% arrived at the training feeder in the direction trials (five-feeder fan-shaped array, accuracy of at least ±6° of azimuth at 50 m from the nest), and 88.62% arrived at the training feeder in the distance trials (five-feeder linear array, accuracy of at least ±5 m or ±10% at 50 m from the nest). Thus, S. mexicana reactivated foragers can find the indicated food source at a specific distance and direction with high precision, higher than that shown by honeybees, Apis mellifera, which do not communicate food location at such close distances to the nest.