MODELING OF THE GREAT LAKES WATER SYSTEM1

There have been two predominate approaches to the modeling of the Great Lakes water system: physical models and mathematical models. The physical models have been of individual lakes whereas the mathematical models have varied from models of individual processes such as evaporation occurring in one portion of one lake to models which include all water quantity components for all five Great Lakes. The assumptions and limitations of the two approaches are presented along with the kinds of results to be expected from each type of modeling. Examples of previous modeling efforts are given to illustrate these assumptions, limitations, and results. Other areas requiring further research are outlined.     

Trophy Hunting and Wildlife Conservation in Zambia

For wildlife conservation to succeed in developing countries, people who live in or near protected areas must receive benefits that offset the costs of their reduced access to natural resources. International trophy hunting is currently generating significant economic benefits for residents of game management areas in Zambia. This has been made possible through a revolving fund and an administrative program that direct revenues from trophy hunting to local wildlife management and community development projects. Benefits might be enhanced by better biological information for management, greater local participation in the allocation and operation of hunting concessions, and the promotion of ecological and ethical standards for trophy hunting. An international system of certification for trophy hunting operations could foster these improvements.     

Decrease of time for pathogen inactivation in alkaline disinfection systems using pressure.

From field studies conducted by Tulane University (New Orleans, Louisiana), efficiency of advanced alkaline disinfection in closed systems was found to depend on ammonia concentration, pH, exposure time, temperature, total solids content, pretreatment storage time, and mixing effectiveness. In this study of a closed alkaline system, an additional pathogen stressor pressure was tested. The effect of the alkaline dosing has been assessed for dewatered raw and aerobically and anaerobically digested municipal sludge cake that produce un-ionized ammonia at concentrations of 0.05 to 2% on a dry-weight basis. Inactivation of Ascaris suum eggs increased from 50 to 99% as the temperature was increased from 40 to 55 degrees C, thus achieving Class A levels. The systems studied were compared with an alkaline process operated under open conditions, which limited the concentrations of ammonia available because of Henry's Law. Under a closed pressurized system, the effect of un-ionized ammonia was greatly increased, and the resulting time required for inactivation was reduced from hours or days to minutes. In the next few years, it is expected that alkaline disinfection of biosolids will be optimized in relation to the factors stated above, at much lower doses of the alkaline agents. The closed-system alkaline processes that will be developed will be more energy-efficient, cost-effective, and have full control of potential odorous emissions.     

Determinants of reproductive success of the White-browed Sparrow Weaver,Plocepasser mahali

Summary Variation in reproductive success among 26 communal groups in a sampled population of Plocepasser mahali (White-browed Sparrow Weaver) was studied over a 3-year period in Zambia, Africa. Potential determinants of reproductive success, namely resource variables and group size, were examined and statistically analyzed for their significance in explaining annual variance in reproductive success among these groups. Resource variables included abundance of grass seeds (dry season food) and grasshoppers (wet season food), nest tree quality, and percentage availability of preferred feeding cover. Only the latter two proved appropriate for this analysis. Patterns of utilization did not correlate positively with food abundance, and grasshopper abundance fluctuated too much among the groups in a given year to be treated as a stable variable.From an analysis of multiple correlation coefficients in a stepwise multiple regression model, both group size and ground cover explained independently of each other 20%–30% of the variance in annual production of young surviving 6 months. Explained variance by these two variables also revealed that their relative importance varied considerably between years. Hypotheses are offered to explain the possible causal mechanisms these variables may have in influencing intergroup reproductive success and the possible reasons why vagaries in explained variance were observed. It is suggested that effects of group size and habitat quality may be more important than age-specific effects in modeling population growth and regulation for species like P. mahali.     

Monitoring and assessment of soil and forage molybdenum near an atmospheric source

Forage and soil molybdenum (Mo) were measured in the vicinity of a Mo processing plant in southwestern Pennsylvania, USA. Molybdenum concentrations in red clover plants (Trifolium pratense L.), measured at 23 sites, ranged from 1.1 to 56.6 mg kg^–1. Fourteen of the 23 sites sampled had red clover plants with Mo concentrations over the threshold value of 6 mg kg^–1. Red clover Cu:Mo concentration ratios were below the recommended ratio of 4 in 19 of the sites. The low Cu:Mo values, along with high plant Mo concentrations, indicates that there is a potential risk of molybdenosis in ruminant animals in this area. Acid digested (sorbed) soil Mo concentrations, measured at 30 sites, ranged from 7.0 (background level) to 131 mg kg^–1. Using the Baker Soil Test (BST) extract, molybdenum soil concentrations ranged from 0.01 to 3.99 mg kg^–1. Regression equations were developed to predict plant uptake of soil Mo based on the red clover plant, soil extracts and soil pH data. The R-squared values for predicting plant uptake were 81.9% for the BST extract and 81.6% for the acid digestion extract plus soil pH. Based on the above results, a protocol has been implemented for assessing the risk of high soil Mo near this Mo processing plant.     

A dental stool with chest support reduces lower back muscle activation

Activation of back musculature during work tasks leads to fatigue and potential injury. This is especially prevalent in dentists who perform much of their work from a seated position. We examined the use of an ergonomic dental stool with mid-sternum chest support for reducing lower back muscle activation. Electromyography of lower back extensors was assessed from 30 dental students for 20?s during three conditions in random order: (a) sitting upright at 90° of hip flexion on a standard stool, (b) leaning forward at 80° of hip flexion on a standard stool, and (c) leaning forward at 80° of hip flexion while sitting on an ergonomic stool. Muscular activity of the back extensors was reduced when using the ergonomic stool compared to the standard stool, by 33–50% (p?相似文献   

Frugal cannibals: how consuming conspecific tissues can provide conditional benefits to wood frog tadpoles (Lithobates sylvaticus)

Tadpoles show considerable behavioral plasticity. When population densities become high, tadpoles often become cannibalistic, likely in response to intense competition. Conspecific tissues are potentially an ideal diet by composition and should greatly improve growth and development. However, the potential release of alarm cues from the tissues of injured conspecifics may act to deter potential cannibals from feeding. We conducted multiple feeding experiments to test the relative effects that a diet of conspecifics has on tadpole growth and development. Results indicate that while conspecific tissues represent a better alternative to starvation and provide some benefits over low-protein diets, such a diet can have detrimental effects to tadpole growth and/or development relative to diets of similar protein content. Additionally, tadpoles raised individually appear to avoid consuming conspecific tissues and may continue to do so until they suffer from the effects of starvation. However, tadpoles readily fed upon conspecific tissues immediately when raised with competitors. These results suggest that cannibalism may occur as a result of competition rather than the specific quality of available diets, unless such diets lead to starvation.     

Assessment of air quality benefits from national air pollution control policies in China. Part I: Background,emission scenarios and evaluation of meteorological predictions

Under the 11th Five Year Plan (FYP, 2006–2010) for national environmental protection by the Chinese government, the overarching goal for sulfur dioxide (SO₂) controls is to achieve a total national emissions level of SO₂ in 2010 10% lower than the level in 2005. A similar nitrogen oxides (NO_x) emissions control plan is currently under development and could be enforced during the 12th FYP (2011–2015). In this study, the U.S. Environmental Protection Agency (U.S.EPA)’s Community Multi-Scale Air Quality (Models-3/CMAQ) modeling system was applied to assess the air quality improvement that would result from the targeted SO₂ and NO_x emission controls in China. Four emission scenarios — the base year 2005, the 2010 Business-As-Usual (BAU) scenario, the 2010 SO₂ control scenario, and the 2010 NO_x control scenario—were constructed and simulated to assess the air quality change from the national control plan. The Fifth-Generation NCAR/Penn State Mesoscale Model (MM5) was applied to generate the meteorological fields for the CMAQ simulations. In this Part I paper, the model performance for the simulated meteorology was evaluated against observations for the base case in terms of temperature, wind speed, wind direction, and precipitation. It is shown that MM5 model gives an overall good performance for these meteorological variables. The generated meteorological fields are acceptable for using in the CMAQ modeling.     

Perspectives on the Use of Green Infrastructure for Stormwater Management in Cleveland and Milwaukee

Green infrastructure is a general term referring to the management of landscapes in ways that generate human and ecosystem benefits. Many municipalities have begun to utilize green infrastructure in efforts to meet stormwater management goals. This study examines challenges to integrating gray and green infrastructure for stormwater management, informed by interviews with practitioners in Cleveland, OH and Milwaukee WI. Green infrastructure in these cities is utilized under conditions of extreme fiscal austerity and its use presents opportunities to connect stormwater management with urban revitalization and economic recovery while planning for the effects of negative- or zero-population growth. In this context, specific challenges in capturing the multiple benefits of green infrastructure exist because the projects required to meet federally mandated stormwater management targets and the needs of urban redevelopment frequently differ in scale and location.