Development of quantitative estimates of uncertainty in environmental risk assessments when the scientific data base is inadequate

The reasons for developing quantitative estimates of uncertainty in environmental risk assessments are discussed along with a method for developing them which involves scientific judgement. In the situation considered here the regulatory needs are ahead of the science, which makes the development of the estimates on uncertainty more difficult, but not impossible. Quantitative estimates for all uncertainties involved in the estimation of risk resulting from exposure to volatile organic compounds (VOCs) in drinking water are developed and tabulated. By far the largest contribution to the uncertainty in the risk estimates for VOCs in drinking water are due to uncertainty in the extrapolation of the dose-response curve to low levels. The uncertainty due to extrapolation is on the order of 10⁴ and 10⁶. Other components of the analysis may contribute uncertainties of a few orders of magnitude. In general the largest uncertainties are in the toxicological data base and the manipulation of it needed to estimate risk. The data base and manipulations needed to estimate exposure due to VOCs in drinking water were at the more an order to magnitudes in uncertainty.     

Health effects of oxidants

Oxidants of significance to human health include ozone, nitrogen dioxide, and peroxyacetylnitrate. All of these compounds are involved in complex photochemical reactions which makes quantification and prediction of their individual health effects difficult. Ozone causes trauma to lung tissues and interferes with enzyme systems in the lungs and other tissues causing a broad range of symptoms. Measurable health impacts can occur at concentrations as low as 390 μg/m³. Acute effects of ozone exposure are reversible at normal urban concentrations (80–120 μg/m³). A special problem of concern, however, is increased susceptibility to infectious diseases contracted through the lungs. Nitrogen dioxide also causes trauma to lung tissues and interferes with enzyme systems. Measurable impacts can occur at concentrations as low as 100 μg/m³, but recovery is rapid and it is not known whether repeated exposures at this level have cumulative effects or predispose the lungs to permanent damage. Chronic exposure of laboratory animals to higher nitrogen dioxide levels can cause emphysema-like conditions and reduction in resistance to respiratory infection. Epidemiological studies of children in houses with gas stoves confirm the finding of reduced resistance to respiratory infection. The U.S. EPA estimates that health effects may occur in young children exposed to concentrations in excess of 280 to 560 μg/m³ one-hour average. These concentrations occur routinely in houses having gas stoves. Peroxyacetylnitrate is a powerful eye irritant in photochemical smog. Other health effects are similar to those of ozone, but less important because of the relatively low concentrations of this pollutant compared to other oxidants.     

An appraisal of emissions control requirements in the California South Coast Air Basin

The purpose of this study is to evaluate the effect of reductions of reactive organic gases (ROG) and NO_x emissions on short-term O₃ and NO₂ concentrations and annual average NO₂ concentrations in the California South Coast Air Basin. Short-term air quality predictions were obtained by applying the Systems Applications Airshed Model to summer O₃ and autumn NO₂ episodes. Effects of emission controls on annual NO₂ concentrations were estimated using CDM and a new parcel tracking model NOXTRAK. Results for the summer O₃ episode indicate that ROG emission reduction in an effective means for reducing peak O₃ concentrations. NO_x emission reduction imposed in addition to ROG emission reductions are counterproductive in reducing peak O₃ concentrations. The modeling results also suggest that attainment of the 1-h federal O₃ standard requires ROG emission reductions on the order of 80% from 1987 levels. Results for the autumn NO₂ episode indicate that NO_x emission reductions approximating those recommended in a proposed Air Quality Management Plan (about 22%) will result in only small (about 5%) reductions in the peak NO₂ concentrations. ROG emission reduction may be more effective than NO_x emission reduction in reducing the peak NO₂ concentration. For the episode studied, a reduction of 36% in ROG emissions is estimated to result in a reduction in peak NO₂ concentrations commensurate with that required to attain the 1-h state NO₂ standard. Model calculations also indicate that the federal NO₂ standard may not be meet by 1987 at one or two stations, but may blosely approached.     

Design,measurement and evaluation of photovoltaic pumping system for rural areas in Oman

In the present paper, the optimum design of a PV system used to operate a water pumping system was determined for Oman. The system design focused on the environmental conditions of Sohar city. The implementation and measurement of the designed system are presented to prove the effectiveness of the proposed system. The results show that the system can provide the required power at peak hours, leading to a substantial reduction in the sizing of the PV system. Consequently, the investment capital costs 2400 USD, and the cost of energy is equal to 0.309 USD/kWh. Furthermore, the results indicate that the system annual yield factor is 2024.66 kWh/kWp and that the capacity factor is 23.05 %, which is encouraging since the latter is typically 21 %. The system capital cost and the cost of energy are worth comparing to a diesel generator. A comparison is made between the proposed system and several others in the literature. The comparison indicated that the system cost of energy is promising.     

Research priorities for managing the impacts and dependencies of business upon food,energy, water and the environment

Delivering access to sufficient food, energy and water resources to ensure human wellbeing is a major concern for governments worldwide. However, it is crucial to account for the ‘nexus’ of interactions between these natural resources and the consequent implications for human wellbeing. The private sector has a critical role in driving positive change towards more sustainable nexus management and could reap considerable benefits from collaboration with researchers to devise solutions to some of the foremost sustainability challenges of today. Yet opportunities are missed because the private sector is rarely involved in the formulation of deliverable research priorities. We convened senior research scientists and influential business leaders to collaboratively identify the top forty questions that, if answered, would best help companies understand and manage their food-energy-water-environment nexus dependencies and impacts. Codification of the top order nexus themes highlighted research priorities around development of pragmatic yet credible tools that allow businesses to incorporate nexus interactions into their decision-making; demonstration of the business case for more sustainable nexus management; identification of the most effective levers for behaviour change; and understanding incentives or circumstances that allow individuals and businesses to take a leadership stance. Greater investment in the complex but productive relations between the private sector and research community will create deeper and more meaningful collaboration and cooperation.     

Effect of rise in spring air temperature on the arrival dates and reproductive success of the Song Thrush, <Emphasis Type="Italic">Turdus philomelos</Emphasis> (C.L. Brehm, 1831) in the forest–steppe of the Russian Plain

The effect of rise in spring air temperature on the breeding phenology and reproductive success of the Song Thrush in the Voronezh Nature Reserve have been studied over the periods of 1987 to 1990 and 2008 to 2012. The results show that relatively high air temperatures provide for earlier arrival of the birds from wintering grounds, earlier and more synchronous breeding of the majority of nesting pairs, and an increase in clutch size and proportion of pairs producing two broods per season. Predation pressure on bird nests decreases under such conditions, which markedly improves reproductive success. Climate warming is conducive to increasing breeding productivity of the Song Thrush population as a whole.     

Carbon fluxes from coarse woody debris in southern taiga forests of the Valdai Upland

Studies in three typical forest biotopes of the Valdai Upland were performed to evaluate the stocks and surface area of coarse woody debris from spruce and birch (in linear transects), its colonization by xylotrophic fungi (during reconnaissance surveys), and CO₂ emission (by a chamber method). The stock and surface area were minimum in a paludal birch forest (46.4 m³/ha and 960 m²/ha) and maximum in a decay area of spruce forest (256.1 m³/ha and 3761 m²/ha, respectively). The assemblages of wood-decay fungi had a composition typically found in southern taiga forests. The total CO₂ flux varied from 145 kg C-CO₂/ha per year in the paludal birch forest to 462 kg C-CO₂/ha per year in small herb–green moss spruce forest. It is concluded that air temperature is an informative predictor of seasonal C-CO₂ flux rate from coarse woody debris.     

Dietary overlap among ruminants,geese, and lemmings of Wrangel Island in summer

Trends in the dynamics of herbivore community related to trophic competition in summer have been analyzed on Wrangel Island. The results show that the trophic spectra overlap considerably, resources are partitioned on the principle “weak competitors after strong competitors,” and community dynamics in the absence of extermination depend on specific competitive advantages related to the width of food spectrum. We conclude that the dynamics of this insular community prior to the establishment of nature reserve on the island have been determined by human activities, as well as the structure of arctic herbivore communities in general.