Insights to false positive total cyanide measurements in wastewater plant effluents.

Many publicly owned treatment works in North America are exceeding permitted limits for total cyanide in their wastewater treatment effluents. A recently introduced rapid, segmented, flow-injection analysis procedure using UV digestion and amperometric detection of the membrane-separated cyanide was used to investigate the various scenarios by which elevated cyanide levels might be present in wastewater treatment plant effluent. A number of significant interferences can produce false positive bias during sample analysis with the traditional acid distillation technique, but are minimized or absent with the new analytical method. However, increased levels of cyanide were found in some chlorinated wastewaters compared to the levels before chlorination, suggesting a fast reaction mechanism associated with the disinfectant and some precursor in the wastewater. In particular, the contact of chlorine with nitrite in the presence of a carbon precursor appears to contribute to cyanide formation during wastewater treatment and sample handling. This paper explores the scenarios under which cyanide can form during wastewater treatment as well as those in which a false bias for total cyanide can be obtained during sample processing and provides guidance for appropriate sample handling, screening, and processing to ensure valid analytical results.     

Alternative mating behaviors of the queen polymorphic ant <Emphasis Type="Italic">Temnothorax longispinosus</Emphasis>

Mating behaviors of ants fall into two categories: female calling, in which a female alate releases pheromones that attract males, and male swarming, in which large male aggregations attract females. Female calling is common in species with queens that return to their natal nest to found colonies dependently after mating, while male swarming is common in species with queens that disperse to found independently. In some species that display both founding strategies, a queen-size polymorphism has evolved in which dependent-founding queens are smaller than independent-founding queens. Dependent founding is likely difficult if gynes (virgin queens) are mating in distant swarms. Therefore, a queen may adopt one or the other mating strategy based on its size and founding behavior. We investigated mating behaviors in the queen-polymorphic ant, Temnothorax longispinosus. Observations in laboratory mating arenas indicated that small gynes exhibited significantly lower flight activity than large gynes. Both forms mated in male swarms, and neither form exhibited female calling. The reduced flight activity of the small morph may facilitate returning to the natal nest after mating, provided the mating swarm is located nearby. Therefore, alternative colony-founding behaviors may be possible without the evolution of female-calling behavior; however, the reduced flight activity of small morphs may require that mating swarms are not distant from the natal nest.     

Review of Russian language studies on radionuclide behaviour in agricultural animals: part 1. Gut absorption

An extensive programme of experiments was conducted in the former USSR on transfer of radionuclides to a wide range of different agricultural animals. Only a few of these studies were made available in the English language literature or taken into account in international reviews of gastrointestinal uptake. The paper gives extended information on Russian research on radionuclide absorption in the gut of farm animals performed in controlled field and laboratory experiments from the 1960s to the current time. The data presented in the paper, together with English language values, will be used to provide recommended values of absorption specifically for farm animals within the revision of the IAEA Handbook of Parameter Values IAEA [International Atomic Energy Agency, 1994. Handbook of Parameter Values for the Prediction of Radionuclide Transfer in Temperate Environments, IAEA technical reports series No. 364. International Atomic Energy Agency, Vienna].     

Effects of Disturbance Associated With Seismic Exploration for Oil and Gas Reserves in Coastal Marshes

Anthropogenic disturbances in wetland ecosystems can alter the composition and structure of plant assemblages and affect system functions. Extensive oil and gas extraction has occurred in wetland habitats along the northern Gulf of Mexico coast since the early 1900s. Activities involved with three-dimensional (3D) seismic exploration for these resources cause various disturbances to vegetation and soils. We documented the impact of a 3D seismic survey in coastal marshes in Louisiana, USA, along transects established before exploration began. Two semi-impounded marshes dominated by Spartina patens were in the area surveyed. Vegetation, soil, and water physicochemical data were collected before the survey, about 6 weeks following its completion, and every 3 months thereafter for 2 years. Soil cores for seed bank emergence experiments were also collected. Maximum vegetation height at impact sites was reduced in both marshes 6 weeks following the survey. In one marsh, total vegetation cover was also reduced, and dead vegetation cover increased, at impact sites 6 weeks after the survey. These effects, however, did not persist 3 months later. No effects on soil or water properties were identified. The total number of seeds that germinated during greenhouse studies increased at impact sites 5 months following the survey in both marshes. Although some seed bank effects persisted 1 year, these effects were not reflected in standing vegetation. The marshes studied were therefore resilient to the impacts resulting from 3D seismic exploration because vegetation responses were short term in that they could not be identified a few months following survey completion.     

Concorde Emissions at Dulles International Airport: Results of Measurements

Hamilton, Ontario is an industrial city with a population of 300,000 which is situated at the western end of Lake Ontario. Canada’s two largest iron and steel mills are located here; the city historically has had relatively poor air quality, which has improved markedly in the last 25 years. Concern about the health effects of current air quality recently led us to carry out an epidemiological study of the effects of air pollution on the respiratory health of over 3500 school children. Respiratory health was measured by pulmonary function testing of each child, and by an assessment of each child’s respiratory symptoms via a questionnaire administered to the parents. Previous studies had shown that other environmental factors (e.g. parental smoking, parental cough, socioeconomic level, housing, and gas cooking) might also affect respiratory health, and thus “confound” any potential relationships between health and air pollution. The questionnaire also collected information on many of these confounding factors. For the purposes of initial analysis, the city was divided Into five areas in which differences In air quality were expected. In general, factors which have been associated with poor respiratory health were observed to be more prevalent in areas of poorer air quality.     

Ammonia modeling for assessing potential toxicity to fish species in the Rio Grande, 1989-2002.

Increasing volumes of treated and untreated human sewage discharged into rivers around the world are likely to be leading to high aquatic concentrations of toxic, unionized ammonia (NH3), with negative impacts on species and ecosystems. Tools and approaches are needed for assessing the dynamics of NH3. This paper describes a modeling approach for first-order assessment of potential NH3 toxicity in urban rivers. In this study daily dissolved NH3 concentrations in the Rio Grande of central New Mexico, USA, at the city of Albuquerque's treated sewage outfall were modeled for 1989-2002. Data for ammonium (NH4+) concentrations in the sewage and data for discharge, temperature, and pH for both sewage effluent and the river were used. We used State of New Mexico acute and chronic NH3- N concentration values (0.30 and 0.05 mg/L NH3-N, respectively) and other reported standards as benchmarks for determining NH3 toxicity in the river and for assessing potential impact on population dynamics for fish species. A critical species of concern is the Rio Grande silvery minnow (Hybognathus amarus), an endangered species in the river near Albuquerque. Results show that NH3 concentrations matched or exceeded acute levels 13%, 3%, and 4% of the time in 1989, 1991, and 1992, respectively. Modeled NH3 concentrations matched or exceeded chronic values 97%, 74%, 78%, and 11% of the time in 1989, 1991, 1992, and 1997, respectively. Exceedences ranged from 0% to 1% in later years after enhancements to the wastewater treatment plant. Modeled NH3 concentrations may differ from actual concentrations because of NH3 and NH4+ loss terms and additive terms such as mixing processes, volatilization, nitrification, sorbtion, and NH4+ uptake. We conclude that NH3 toxicity must be considered seriously for its potential ecological impacts on the Rio Grande and as a mechanism contributing to the decline of the Rio Grande fish community in general and the Rio Grande silvery minnow specifically. Conclusions drawn for the Rio Grande suggest that NH3 concentrations may be high in rivers around the world where alkaline pH values are prevalent and sewage treatment capabilities are poorly developed or absent.     

Estimating Fugitive Emissions of Volatile Compounds from Equipment Leaks

This paper is directed to those concerned with estimating releases to the air of volatile compounds from equipment component leaks. We compared emission rates for equipment component leaks using EPA’s Average Emission Factor Method, Leak/No-Leak Emission Factor Method, and Stratified Emission Factor Method. The latter two methods may be used if there are concentration measurements about the components. An organic vapor analyzer was applied with the appropriate response factor to measure the concentrations around each equipment component using EPA Method 21. We analyzed this data to determine mass emission rates. Results show that the Average Emission Factor Method substantially overstates the emission rates calculated using these other two methods. We conclude that use of Method 21 concentration measurements with the Leak/No Leak or Stratified Emission Factor Method may increase the accuracy and reduce significantly the estimated releases to the air of volatile compounds from equipment component leaks for many facilities.     

Cross-sectional survey methods to assess retrospectively mortality in humanitarian emergencies

Since the rates and causes of mortality are critical indicators of the overall health of a population, it is important to evaluate mortality even where no complete vital statistics reporting exists. Such settings include humanitarian emergencies. Experience in cross-sectional survey methods to assess retrospectively crude, age-specific, and maternal mortality in stable settings has been gained over the past 40 years, and methods appropriate to humanitarian emergencies have been developed. In humanitarian emergencies, crude and age-specific mortality can be gauged using methods based on the enumeration of individuals resident in randomly selected households—frequently referred to as a household census. Under-five mortality can also be assessed through a modified prior birth history method in which a representative sample of reproductive-aged women are questioned about dates of child births and deaths. Maternal mortality can be appraised via the initial identification of maternal deaths in the study population and a subsequent investigation to determine the cause of each death.     

Simulating Spatial Pattern and Dynamics of Military Training Impacts for Allocation of Land Repair Using Images

The land management of US Army installations requires information on land conditions and their history for planning future military training activities and allocation of land repair. There is thus a strong need for methodology development to estimate the land conditions and cumulative military training impacts for the purpose of repair and restoration. In this study, we simulated at Fort Riley, USA, spatial patterns and temporal dynamics of military training impacts on land conditions quantified as percent ground cover using an image-aided spatial conditional co-simulation algorithm. Moreover, we estimated the historical percent ground cover as a measure of the cumulative impacts, and then calculated the allocation of land repair and restoration based on both current and historical land conditions. In addition, we developed a loss function method for allocation of land repair and restoration. The results showed: (1) this co-simulation algorithm reproduced spatial and temporal variability of percent ground cover and provided estimates of uncertainties with the correlation coefficients and root mean square errors between the simulated and observed values varying from 0.63 to 0.88 and from 23% to 78%, respectively; (2) with and without the cumulative impacts, the obtained spatial patterns of the land repair categories were similar, but their land areas differed by 5% to 40% in some years; (3) the combination of the loss function with the co-simulation made it possible to estimate and computationally propagate the uncertainties of land conditions into the uncertainties of expected cost loss for misallocation of land repair and restoration; and (4) the loss function, physical threshold, and probability threshold methods led to similar spatial patterns and temporal dynamics of the land repair categories, however, the loss function increased the land area by 5% to 30% for intense and moderate repairs and decreased the area by 5% to 30% for no repairs and light repairs for most of the years. This approach provided the potential to improve and automate the existing land rehabilitation and maintenance (LRAM) system used for the land management of the U.S. Army installations, and it can be applied to the management of other civil lands and environments. In conclusion, this study overcame the important gaps that exist in the methodological development and application for simulating land conditions and cumulative impacts due to human activities, and also in the methods for the allocation of land for repair and restoration.