COMPARISON OF INSTREAM AND LABORATORY METHODS OF MEASURING SEDIMENT OXYGEN DEMAND1

ABSTRACT: Sediment oxygen demand (SOD) was determined at three sites in a gravel-bottomed central Missouri stream by: (1) two variations of an instream method, and (2) a laboratory method. SOD generally was greatest by the instream methods, which are considered more accurate, and least by the laboratory method. Disturbing stream sediment did not significantly decrease SOD by the instream method. Temperature ranges of up to 12° Celsius had no significant effect on the SOD. In the gravel-bottomed stream, the placement of chambers was critical to obtain reliable measurements. SOD rates were dependent on the method; therefore, care should be taken in comparing SOD data obtained by different methods. There is a need for a carefully researched standardized method for SOD determinations.     

Radioactivity in rainwater following the chernobyl accident

Summary Rainfall is a widely-acknowledged vehicle for the removal and deposition at ground level of atmospheric-borne materials. The events following the Chernobyl accident demonstrated once again the importance of atmospheric conditions in dispersing, transporting and depositing pollutants. Much attention has been paid to the contamination of vegetation and food products, yet the quality of the contaminated rainwater has been overlooked. This paper reports and summarises the findings from Great Britain and Scandinavia and shows that the issue is far from simple or easily understood.Dennis Wheeler is a member of the academic staff in The Geography Department at Sunderland Polytechnic. Throughout this paper the identity of actual recording sites in the UK has not been specified, merely the regions from which the data were gathered. This is in accordance with the wishes of the National Radiological Protection Board, UK.     

WATER BALANCE OF PACIFIC ATOLLS1

ABSTRACT: This study presents an estimate of water balance components for Pacific atolls under average dimatological conditions. Figures show annual potential evapotranspiration, annual recharge for rain-fed and aquifer-fed vegetated areas, and the number of months that potential evapotranspiration exceeds actual evapotranspiration (indicating water stress) under average conditions. The method relies on the assumption that small islands have minimal influence on cloudiness and precipitation. The potential evapotranspiration is computed using the equilibrium evaporation concept, and estimates of monthly soil water storage and recharge follow Thornthwaite's bookkeeping method. Gradients in potential evapotranspiration run primarily north-south, though for the equatorial zone potential evapotranspiration declines from east to west, opposing the trend in rainfall. Recharge estimates range from 250 mm in the central Tuamotu Archipelago and zero in eastern Kiribati to over 2000 mm per year in the southern Caroline Islands (U.S. Trust Territory) and Solomon Islands. The sensitivity of the model to intra-month rainfall variability and a range of available soil moisture values is discussed.     

ACUTE TOXICITY OF PICRIC ACID AND PICRAMIC ACID TO RAINBOW TROUT,SALMO GAIRDNERI,AND AMERICAN OYSTER,CRASSOSTREA VIRGINICA1

ABSTRACT Picric acid (2,4,6-trinitrophenol) and picramic acid (2-amino-4,6-dinitrophenol) are potential water pollutents due to a variety of industrial and munition uses. The possible impacts of picric and picramic acid to two recreationally and commercially important species, rainbow trout, Salmo gairdneri, and American oysters, Crassostrea virginica, were evaluated. Picramic acid was more toxic than picric acid to both species tested. The 96-h LC50s for picric and picramic acids for rainbow trout were 109.6 and 46.2 mg/1, respectively. The 144-h LC50s for picric and picramic acid for American oysters were 254.9 and 69.8 mg/1, respectively. Sublethal no growth EC50s and shell deposition EC50s for oysters showed that both compounds caused adverse effects at much lower concentrations than indicated by the LC50s. For example, the 144-h shell deposition EC50s were 27.9 mg/1 for picric acid and 5.6 mg/1 for picramic acid. Sediment adsorbtion studies in estuarine water indicated that both compounds are not readily adsorbed which suggests that sediment would not play a major role as a sink in contaminated systems. Oysters, which filter large quantities of particulate matter, would more likely be affected by picric and picramic acids in the water column than by exposure to contaminated sediment.     

LAKE LEVEL DRAWDOWN AS A MACROPHYTE CONTROL TECHNIQUE1

ABSTRACT: Lake drawdown as a management or restoration technique for controlling macrophytes in eutrophic lakes is reviewed for effectiveness, longevity, and positive and negative impacts. Drawdown can be effective but is species specific, and some nuisance plants are resistant or stimulated. The responses of 63 nuisance plants are reviewed. Advantages of the technique include low cost, absence of toxic chemicals, enhancement of fisheries, and the opportunity to carry out other lake improvements. Drawbacks include nutrient release, algal blooms, low dissolved oxygen, lake user dissatisfaction during the process, and failure to refill. The technique is recommended for situations where susceptible species are the major nuisance and where prolonged (1–2 months) dewatering of sediments under rigorous conditions of heat or cold is possible.     

Associations and lags between air pollution and acute respiratory visits in an ambulatory care setting: 25-month results from the aerosol research and inhalation epidemiological study

Particulate matter (PM) has been associated with adverse respiratory outcomes in numerous studies that utilized data from emergency room visits, hospital admissions, and mortality records. This study is unique in its investigation of associations of air pollution measures, including components of PM, with health outcomes in an ambulatory-care setting. Visit data were collected from Kaiser Permanente, a not-for-profit health maintenance organization in the metropolitan Atlanta, GA, area. Kaiser Permanente collaborated on the Aerosol Research Inhalation Epidemiological Study (ARIES), which provided detailed information on the characteristics of air pollutants. The Kaiser Permanente study was a time-series investigation of the possible associations between daily levels of suspended PM, inorganic gases, and polar volatile organic compounds and ambulatory care acute visit rates during the 25-month period from August 1, 1998, to August 31, 2000. For this interim analysis, the a priori 0-2 days lagged moving average, as well as the 3-5 days and 6-8 days lagged moving averages, of air quality measures were investigated. Single-pollutant Poisson general linear modeling was used to model daily visit counts for asthma and upper and lower respiratory infections (URI and LRI) by selected air quality metrics, controlling for temporal trends and meteorological variables. Most of the statistically significant positive associations were for the 3-5 days lagged air quality metrics with child asthma and LRI.     

Impacts of environmental factors on urban heating

This study investigated the impact of important environmental variables (i.e.,wind speed,solar radiation and cloud cover) on urban heating.Meteorological parameters for fifteen years (from 1990 to 2005),collected at a well developed and densely populated commercial area (Tsim Sha Tsui,Hong Kong),were analyzed in details.Urban heat island intensity (UHII),a well known indicator of urban heating,has been determined as the spatially averaged air-temperature difference between Tsim Sha Tsui and Ta Kwu Ling (a thinly populated rural area with lush vegetation).Results showed that the UHII and cloud cover have increased by around 9.3% and 4%,respectively,whereas the wind speed and solar radiation have decreased by around 24% and 8.5%,respectively.The month of December experienced the highest UHII (10.2°C) but the lowest wind speed (2.6 m/sec) and cloud cover (3.8 oktas).Conversely,the month of April observed the highest increases in the UHII (over 100%) and the highest decreases in wind speed (over 40 %) over fifteen years.Notably,the increases in the UHII and reductions in the wind speed were the highest during the night-time and early morning.Conversely,the intensity of solar radiation reduced while the intensity of urban cool island (UCII) increased during solar noon-time.Results demonstrated strong negative correlation between the UHII and wind speed (coefficient of determination,R2=0.8) but no negative correlation between UCII and solar radiation attenuation.A possible negative correlation between UHII and cloud cover was investigated but could not be substantiated.     

中国必须抓住金融危机里蕴含的机遇

3月7号,胡锦涛主席在全国人民代表大会上指出,危机也意味着机会。当我们同时谈及金融和生态危机时,这显得尤为正确。虽然目前经济危机带来了严重的问题,但如果不解决富人对自然资源的过度消费,我们将面临灾难性的后果。与之相比,经济危机的影响不免相形见绌。如果地球上每一个人都像美国人一样消耗资源,我们将需要不止五个地球。     

The impact of intersection design on simulated driving performance of young and senior adults

PURPOSE: The Federal Highway Administration (FHWA) proposed guidelines for highway design to increase the safe driving ability of older drivers; however, little empirical evidence exists to support the effectiveness of these guidelines. The purpose of this study was to investigate the effects of implementing these guidelines (in 4 pairs of intersections) on safe driving performance of older and younger drivers using a high-fidelity driving simulator. DESIGN AND METHODS: We replicated four intersection pairs (improved versus unimproved) in a high-fidelity, virtual reality driving simulator. Simulator scenarios were created from actual road locations, replicating road geometrics and traffic control devices. The simulator's controls were integrated with an actual vehicle to make the driving experience as realistic as possible. Kinematic measures were obtained from the simulator in conjunction with driving errors recorded by trained driving evaluators sitting in the cab of the car. Thirty-nine subjects, 19 younger and 20 older adults, participated in the study. RESULTS: For the kinematic data we found greater lateral control, as indicated by significantly smaller maximum yaw during the turn phase, at all of the improved intersections when compared to the unimproved intersections. We found some significant age differences, but mostly in only one of the intersection-pairs. For the behavioral data, there were significant differences in driving errors between improved and unimproved intersections in two intersection-pairs; however, there were no significant differences in driving errors between the older and younger drivers. IMPLICATIONS: The findings suggest that both young and older drivers may benefit from roadways with safety features recommended by the FHWA guidelines as indicated by the increased lateral control of the vehicle when negotiating these intersections. These findings generate critical information for those involved in the design of roadway systems.     

The impact of roadway intersection design on driving performance of young and senior adults

OBJECTIVE: To test the effectiveness of the FHWA guidelines for intersection design. METHODS: In an experimental design we used kinematics measures from an instrumented vehicle and behavioral (error) data collected during on-road evaluations to quantify the effects of improved versus unimproved intersections (turn phase) and to determine if these intersections were safer (vehicular stability and driver confidence) for both older (65-85 years) and younger (25 -45) drivers. We analyzed kinematics data with a 2 x 2 repeated measures ANOVA and behavioral data (driving errors yes, no) with Wilcoxon sign rank test (within subject variable: intersection improved vs. unimproved) and Wilcoxon rank sum test (between subject variable: age, younger vs. older driver). RESULTS: Kinematics measures (turn phase), showed three maneuvers had statistically significantly lesser side forces (measured by lateral acceleration and combined acceleration) for the improved conditions, and four maneuvers had statistically significantly greater, yet appropriate, speeds for the improved conditions. Lesser side forces indicated improved lateral stability and increased speed indicated greater confidence. Drivers made fewer errors on two of the improved intersections; but across all maneuvers, older drivers appeared to make fewer errors on the improved intersections. CONCLUSIONS: This study brings empirical intersection design and safety information for engineers and city planners to consider as they plan and develop intersections. Future researchers may want to use the conceptual and analytical framework of this study to determine the effectiveness of other FHWA guidelines. Given that these intersection design guidelines benefit younger and older drivers alike, plausible policy-making opportunities are opened in the design of safe roadway systems, to benefit the broad spectrum of adult drivers.